Ebook Reoperations in cardiac surgery: Part 1

(BQ) Part 1 book Reoperations in cardiac surgery has contents: Investigation before reoperations for congenital heart disease, investigations before reoperation for acquired heart disease, anaesthesia for cardiac reoperations, reoperations in the presence of infection,... and other contents.

J Stark and A.D Pacifico (Eds.)

Illustrations by M Courtney

Reoperations in Cardiac Surgery

Foreword by David C Sabiston, Jr

With 388 Figures

Springer-Verlag

London Berlin Heidelberg New York Paris Tokyo Hong Kong

Consultant Cardiothoracic Surgeon, The Hospital for Sick Children, Great Ormond Street, London WCIN 3JH, UK

Albert D Pacifico, MD

Professor and Director, Division of Cardiothoracic Surgery, University of

Alabama at Birmingham, University Station, Birmingham, Alabama 35294, USA

ISBN-13:978-1-4471-1690-5 e-ISBN-13:978-1-4471-1688-2

DOl: 10.1007/978-1-4471-1688-2

British Library Cataloguing in Publication Data

Reoperations in cardiac surgery

I Man Heart Surgery

Reoperations in cardiac surgery / J Stark and A.D Pacifico

(eds.) ; foreword by D Sabiston

p cm

Includes bibliographies and index

ISBN 0-387-19552-1

1 Heart-Reoperation 2 Congenital heart disease-Reoperation

I Pacifico, Albert D II Title

[DNLM: I Heart Surgery 2 Surgery Operative WG 169 S795r)

RD598.35.R46S73 1989

617' 4 1 2 dc19

This work is subject to copyright All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation broadcasting, reproduction on microfilms or in other ways, and storage in data banks Duplication of this publication or parts thereof is only permitted under the provisions of the German Copyright Law of September 9, 1965,

in its version of June 24, 1985, and a copyright fee must always be paid Violations fall under the prosecution act of the German Copyright Law

© Springer-Verlag Berlin Heidelberg 1989

Softcover reprint of the hardcover 1 st edition 1989

The use of registered names, trademarks etc in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use

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Filmset by Photographics, Honiton, Devon

2128/3916-543210 (Printed on acid-free paper)

Foreword

Nearly a century has passed since Rehn performed the first successful cardiac operation by closing a right ventricular stab wound in a gravely ill patient Moreover, it has been more than fifty years since Gross successfully corrected the first congenital cardiac malformation in 1938 by suture ligation of a patent ductus arteriosus The introduction of the Blalock operation for tetralogy of Fallot by Blalock in 1944 greatly advanced the management and prognosis of a critically ill group of cardiac patients, and the success of this procedure further stimulated the development of concepts and techniques for the surgical management of other severe congenital cardiac defects Until the successful use of extracorporeal circulation by Gibbon in 1953, it was often necessary to perform cardiac operations which were palliative rather than curative procedures With the advent of additional new and improved techniques, correction of many hitherto incurable cardiac disorders became possible and reoperation under these circumstances became frequent

Cardiac surgery is very fortunate in having two master surgeons, whose distinctive contributions and clinical proficiency are recognized worldwide, to edit this extraordinary and unique text They have placed emphasis on a number of specific complications of primary cardiac procedures which lead to the necessity for reoperation Problems associated with postoperative infections, thrombotic dis-orders, stenoses of suture lines, deterioration of prosthetic materials and mechanical valves, rejection of transplanted organs and tissues, and a host of additional complications are described together with their appropriate surgical management The ·Editors have selected 14 other authorities in both acquired and congenital disease to record their experiences and solutions to these vexing problems The initial chapters concern the necessity to obtain preoperatively as much information as possible on the cardiac lesions requiring correction Specific attention

is given to the roles of angiocardiography, digital subtraction angiography, cardiac catheterization, echocardiography, chest roentgenography, computed transaxial tomographic scanning (CT), magnetic resonance imaging, electrocardiography, and other appropriate techniques The authors deserve special commendation for the thoroughness found in each section as well as the excellence of the illustrations which depict the stepwise correction of the various problems Similarly, examples

of the diagnostic studies are beautifully reproduced with their significant features being made obvious to the reader Each subject is carefully referenced with a select and up-to-date bibliography It is apparent that the authors have given each subject maximal thought and attention in the preparation of this very laudable text Each of the common cardiac procedures is included as are a number of less frequently encountered but nevertheless very significant problems requiring

reoperation The reader is particularly struck with the obvious familiarity of each contributor with the subject presented, which provides gratifying confidence to those undertaking these reoperations

In summary, Reoperations in Cardiac Surgery is a very timely contribution edited

by two of the most renowned contemporary cardiac surgeons with additional contributors of similar stature Of maximal current significance, this masterwork will predictably become a widely used and frequently cited reference as well as an essential part of the library of all cardiac surgeons

Preface

More cardiac operations are performed each year The incidence of reoperations

is also increasing There are several reasons for this increase: failure of mechanical and biological valve substitutes, conduits and coronary bypass grafts, erroneous diagnosis, incomplete repair and infection In surgery of congenital heart defects replacement of the original prosthetic valve is required if the child outgrows the prosthesis Reoperation may also be part of a staged repair for a complex lesion

or may be required for residual or recurring defects

The purpose of this book is to provide information about the diagnosis of early and late complications, the indications for reoperation and the optimal timing of reoperation The main emphasis is on the description of safe surgical techniq"ues The book is divided into three sections The general part includes chapters on diagnosis, anaesthesia, surgical approaches to the heart and great vessels, reoperations in the presence of infection, postoperative mediastinitis, pacemakers, and heart and heart-lung transplantation The second section describes surgical techniques used for reoperations of congenital heart defects All common defects are included To avoid repetition and too lengthy text some combinations of lesions are not discussed separately They are described either in the congenital or the acquired heart defect section although they can have both aetiologies The third section on acquired heart disease includes chapters on coronary arteries, mitral and tricuspid valves, arrhythmia and thoraco-abdominal aneurysms

The authors describe the techniques which gave them, over the years, the best results Some alternatives are mentioned without an attempt to cover all published techniques The text relies on Michael Courtney's illustrations He worked very closely with the Editors and was able to transform sketches made by individual authors into instructive three-dimensional illustrations With a few exceptions all drawings are oriented as the heart is seen by the operating surgeon

This book should provide information to a young surgeon who does not have a large experience with reoperations We hope that it will also be useful to established surgeons, especially in the chapters on the less common lesions or complications

It may also be of interest to cardiologists, cardiac anaesthetists, radiologists, intensive care personnel and nurses We believe that a well-performed original operation will lead to a minimal number of complications However, when residual

or recurring defects cause haemodynamic problems, correctly timed and expertly performed reoperations may return the patient to normal health and an active life

We hope that the book will contribute to this goal

J Stark, MD, FRCS, FACS

Consultant Cardiothoracic Surgeon

A.D Pacifico, MD Director, Division of Cardiothoracic Surgery

Acknowled2ements

We would like to express our thanks to Dr G.R Graham, former Clinical Physiologist at The Hospital for Sick Children, Great Ormond Street, for his suggestion to write this book Our thanks are due to all the contributors for preparing the text, for allowing considerable e~itorial changes to achieve uniformity and for their co-operation in working with one artist

Michael Courtney made a great contribution to this book His clear understanding

of the points we wanted to illustrate and his ability to transfer them into quality illustrations will, we hope, be appreciated by the readers

high-Our thanks are due to our secretaries, Miss V Parkhouse, Miss P Hunter, and especially Mrs S Croot, Research Secretary in the Cardiothoracic Unit at The Hospital for Sick Children, Great Ormond Street, who has helped with the collection of the material, researched literature, and edited and transcribed all the manuscripts

Consultant Cardiothoracic Surgeon

A.D Pacifico, MD Director, Division of Cardiothoracic Surgery

Contents

Contributors xix

Abbreviations xxiii

Section I: General 1 Investigation Before Reoperations for Congenital Heart Disease 1 F N Taylor 3

Introduction 3

Staged Procedures 4

Residual Lesions 5

Clinical Considerations 5

Non-~nvasive I~ves.tigation 8

Invasive Investigation 10

Recurrent Lesions 13

Changes Resulting from Growth, and Deterioration in Prosthetic Function 14

Prognosis After Completion of Intended Management 15

Conclusion : 16

2 Investigations Before Reoperation for Acquired Heart Disease Celia M Oakley 17

Introduction 17

Methods of Investigation 17

Non-invasive Investigation 17

Invasive Investigation 18

Reasons for Failure of Previous Operations 19

Wrong Indication or Wrong Operation 19

Valve Disease 19

After Pericardiectomy 25

Special Problems , ; 26

The Myocardium 26

Marfan's Syndrome 27

Myxoma and Other Cardiac Tumours 27

Pregnancy 28

Traumatic Heart Disease 29

Emergencies 29

Mechanical Disasters 29

Prosthetic Valve Thrombosis "Encapsulation" 30

Infective Endocarditis 31

Reoperation After Previous Coronary Bypass Surgery 33

Pericardial Syndromes 35

Postoperative Pericardial Collection 35

Conclusion , 35

3 Anaesthesia for Cardiac Reoperations M Scallan 39

Introduction 39

Preoperative Assessment 39

Anaesthesia 40

Monitoring 40

Specific Conditions 41

Reoperation for Coronary Artery Bypass Grafts 41

Valvar Heart Disease 41

Congenital Heart Disease 42

Postoperative Complications 42

Conclusion 42

4 Approaches to the Heart and Great Vessels at Reoperation J Stark 43

Introduction 43

Sternal Re-entry 44

Prevention 44

Operative Technique 45

Results 51

Re-thoracotomy 51

Conclusion 52

5 Reoperations in the Presence of Infection L H Cohn 55

Introduction 55

General Considerations 55

Indications for Surgery 56

Prosthetic Valve Endocarditis 56

Infected Aortocoronary Bypass 57

Infected Cardiac Suture Line 57

Surgical Technique 58

Reoperation in the Presence of Infected Prosthetic or Bioprosthetic Valves 58

Surgical Technique for the Infected Cardiac Suture Line 64

Surgical Treatment of Infected Coronary Bypass Graft 64

Results 65

Conclusions and Summary 66

6 Pacing: Indications, Technique of Insertion and Replacement of Leads and Generators P G Rees 67

Introduction ' 67

Description of Generators 1 67

Indications for Permanent Pacemaker Insertion 68

Choice of Pacing Systems 69

Generator , '" 69

Wire 70

Pacing 71

Temporary 71

Permanent 71

Generator Implantation " 75

Pectoral/Axillary Approach 76

Subxiphoid Approach 76

Suprarenal Approach 76

Reoperation 77

Pulse Generator Replacement 77

Pacemaker Lead Problems 78

Pacemaker System Replacement for Infection 78

Follow-up 78

Restrictions , 79

Conclusion 80

7 Postoperative Mediastinitis P.F Sauer and L.O Vasconez 81

Introduction 81

Aetiology 81

Bacteriology 81

History of Management Options 82

Sternal Blood Supply " 82

Reconstructive Options 83

Omentum 83

Pectoralis Major 85

Rectus Abdominis 86

Complications 88

Mediastinitis in Infants and Children 90

Conclusions 90

8 Heart and Lung Retransplantation M.R Mill and E.B Stinson 93

Cardiac Retransplantation 93

Introduction , " , 93

Indications for Retransplantation 93

Technique of Retransplantation 93

Postoperative Care 98

Results at Stanford University Hospital ; 98

Summary 99

Heart-Lung Retransplantation 100

Introduction 100

Indications for Retransplantation 100

Technique of Retransplantation 100

Postoperative Care 102

Results 102

Summary 103

Section II: Congenital Heart Disease

9 Reoperations After Repair of Coarctation of the Aorta

J Stark 107

Introduction 107

Problems Following Repair of Coarctation 107

Residual/Recurrent Coarctation (Re-coarctation) 108

Aneurysm/Pseudoaneurysm 109

Chylothorax ;- 110

Phrenic Nerve Palsy 111

Vocal Cord Palsy 111

Systemic Hypertension 111

Operative Technique ; 112

Re-coarctation c ••••••••••••••••••••••••••••••••••••••••••• 112 Repair of Aneurysm/Pseudoaneurysm 120

Results 120

Residual/Recurrent Coarctation of the Aorta 120

Aneurysm/Pseudoaneurysm 121

10 Reoperations for Interrupted Aortic Arch J.L Monro 125

Introduction " 125

Problems 126

Stenosis of the Aortic Anastomosis 126

Subvalvar Stenosis 127

Valvar Stenosis 127

Supravalve Stenosis 127

Residual VSD 127

Previous Palliation 127

Operative Techniques 127

Techniques for First Operation 127

Technique for Reoperation 131

Postoperative Care 136

Results 136

Conclusion 140

11 Reoperations After Repair of Total Anomalous Pulmonary Venous Connection D.l Hamilton and H.J CM van de Wal 143

Introduction ; 143

Problems 143

Complications Requiring Medical Management 144

Complications Requiring Surgical Management 145

Surgical Technique 151

Original Operation 151

Reoperation 154

Postoperative Management 158

Results 158

Early Results - Mortality After the Primary Operation 158

Late Deaths Following the Primary Operation 158

12 Reoperations After Closure of Ventricular Septal Defects

M.R de Leval 161

Introduction 161

Problems 161

Residual or Recurrent Intracardiac Shunt 161

Arterial Valve Damage 163

Atrioventricular Valve Dysfunction 163

Outflow Tract Obstructions 163

Haemolysis 164

Postoperative Bacterial Endocarditis 164

Conduction Disturbances 164

Surgical Techniques 165

Residual/Recurrent Intracardiac Shunts : 165

Additional VSDs 166

Aortic Valve Regurgitation 167

Atrioventricular Valve Dysfunction 168

Outflow Tract Obstructions 168

Haemolysis 169

Endocarditis 169

Pacemaker Insertion 169

Postoperative Care 169

13 Reoperations After Repair of Tetralogy of Fallot A.D Pacifico 171

Introduction 171

Problems, Diagnosis and Indication for Reoperation 174

Residual or Recurrent VSD 174

Residual RVOTO 175

Pulmonary Insufficiency 175

Tricuspid Valve Insufficiency 176

Right Ventricular Aneurysm 176

Residual ASD 177

Residual Surgical Shunt 177

Surgical Technique 177

Repair of Residual or Recurrent VSD 177

Repair of RVOTO 179

Repair of Pulmonary Insufficiency 182

Repair of Tricuspid Valve Insufficiency 182

Repair of Right Ventricular Aneurysm 183

Repair of ASD 183

Repair of Residual Surgical Shunt 183

Postoperative Care 183

Results 183

14 Reoperations After Mustard and Senning Operations J Stark 187

Introduction 187

Problems 188

Mustard Operation 188

Senning Operation 192

Operative Technique 194

Mustard 194

Senning 201

Results of Reoperations After Mustard or Senning Procedures 205

15 Reoperations After Arterial Switch Operation A.R Castaneda 209

Introduction " " 209

Complications 209

Surgical Technique 211

Original Operation 211

Reoperation , 213

Results : 214

16 Arterial Switch for Right Ventricular Failure Following Mustard or Senning Operations R.B.B Mee 217

Introduction 217

Problems 218

Related to Previous Atrial Repair 218

Related to the Concept of Atrial Repair 219

Management and Surgical Technique 220

Stage I Pulmonary Artery Banding for RV Failure After Mustard/ Senning 220

Stage II Conversion of Mustard/Senning to Arterial Switch 223

17 Aortic Valve Reoperations A.D Pacifico 233

Introduction " " " " 233 Secondary Aortic Valvotomy for Congenital Valvar Aortic Stenosis 233

Problems 233

Indication for Reoperation 234

Surgical Technique 234

Postoperative Care ; 237

Results 237

Secondary Aortic Valve Replacement 238

Problems 238

Indications for Reoperation 238

Operative Technique 238

Postoperative Care 243

Results ~ " " 243

Enlargement of the Small Aortic Annulus 244

Problems and Indications for Reoperation 244

Operative Technique 245

Results 246

18 Reoperations for Residual/Recurrent Left Ventricular Outflow Tract Obstruction P.A Ebert 249

Introduction '" , " " , " 249

Problems Following Initial Aortic Valvotomy 249

Residual/Recurrent Aortic Stenosis 249

Aortic Insufficiency 250

Coronary Artery Insufficiency 250

Supravalvar Aortic Stenosis 250

Subvalvar Aortic Stenosis 250

Problems Following Operative Repair of Subvalvar Aortic Stenosis 250

Conduction Problem 250

Aortic Valve Injury 250

Mitral Valve Injury 251

Ventricular Rupture 251

Diagnosis and Evaluation 251

Operative Technique 251

Konno Aortoventriculoplasty 252

Left Ventric1e to Aorta Conduit 255

Postoperative Management 256

Results 256

19 Aortic Root Replacement D.N Ross and Roxane McKay 259

Introduction 259

Indications for Reoperation 260

Left Ventricular Outflow Tract Obstruction 260

Aortic Regurgitation 261

Structural Defects 261

Endocarditis 262

Operative Technique of Aortic Root Replacement 262

General Considerations 263

Homograft Replacement of the Aortic Root 265

Reoperation After Homograft Aortic Root Replacement 268

Postoperative Management 268

Results 269

20 Reoperations in Patients with Extracardiac Valved Conduits J Stark 271

Introduction 271

Problems 271

Complications Related to Conduit Insertion 272

Complications Unrelated to Conduit Insertion 276

Operative Technique 278

General 278

Sternal Re-entry, Re-thoracotomy and Cannulation 279

Conduit Replacement 280

Replacement of Systemic (Tricuspid) Atrioventricular Valve in Patients with Congenitally Corrected Transposition 284

Truncal Valve Incompetence 284

Recurrent/Residual VSD 284

Conduit or Ventricular Aneurysm/Pseudoaneurysm 285

Recurrent/Residual Left Ventricular Outflow Tract Obstruction 285

Residual/Recurrent Pulmonary Branch Stenoses 286

Residual/Recurrent Major Aortopulmonary Collaterals 287

Infection 287

Postoperative Care 287

Results 288

21 Reoperations After the Fontan Procedure

F Fontan, G Fernandez and 1 Stark 291

Introduction 291

Diagnosis of Problems and Indications for Reoperation 291

Early Problems 291

Late Problems 293

Surgical Techniques/Treatment 295

Early Problems 295

Late Problems 298

Postoperative Care 302

Results 303

22 Reoperations for Atrioventricular Discordance M R de Leval 305

Introduction 305

Problems 305

Recurrent or Increasing L VOTO 305

Residual/Recurrent VSDs / 306

Systemic Atrioventricular Valve Regurgitation and Systemic Ventricular Failure 306

Conduction Disturbances 307

Surgical Considerations 307

Anatomical Landmarks 307

Surgical Techniques 309

Postoperative Care 311

Results 311

Section III: Acquired Heart Disease 23 Reoperations for Coronary Artery Disease D.M Cosgrove, III and F.D Loop 315

Incidence 315

Indications for Reoperation 316

Surgical Technique 317

Results 322

Conclusions 322

24 Reoperations on the Mitral and Tricuspid Valves C.G Duran 325

Mitral Valve : 325

Introduction ' 325

Problems " 326

Mitral Valve Conservative Surgery 326

Causes and Incidence of Re-stenosis 326

Causes and Incidence of Residual/Recurrent Regurgitation 328

Diagnosis of Valve Malfunction and Timing of Reoperation 330

Mitral Valve Replacement 331

Surgical Technique 331

Prosthesis-related Problems 332

Patient -related Problems 333

Operative Technique:Access to Mitral Valve 334

Operative Technique: Surgery After Mitral Reconstruction 338

Operative Technique: Valve Re-replacement 340

Tricuspid Valve 343

Introduction 343

Problems 344

Tricuspid Problems Overlooked During the Original Operation 344

After Commissurotomy and Annuloplasty 344

After Tricuspid Valve Replacement 345

Operative Technique 345

Access to Tricuspid Valve 345

Reoperation on Triscuspid Valve 346

Postoperative Care 347

Results 347

25 Reoperations in the Surgical Treatment of Arrhythmias 1.K Kirklin 351

Reoperations for WPW 351

Diagnosis and Indications - 351

Surgery 352

Postoperative Care 355

Results ; 355

Reoperations for Direct Surgical Relief of Ventricular Tachycardia 355

Diagnosis and Indications 356

Surgery 356

Postoperative Care 358

Results 358

Implantation of the Automatic Cardioverter/Defibriliator After Previous Sternotomy 358

Diagnosis and Indications 358

Surgery 359

Postoperative Care 359

Results 359

26 Reoperations for Thoracic and Thoracoabdominal Aneurysms E.S Crawford, 1.S Coselli and H.J Safi 361

Introduction 361

Involvement of Multiple Aortic Segments 361

Progression of Disease 362

Problems 362

Ascending Aorta and Aortic Arch 362

Descending and Thoracoabdominal Aorta 368

Diagnosis 370

Operative Technique 372

Perfusion Techniques and Hypothermia 372

Current Reconstruction Techniques 373

Results of Reoperation 379

Ascending Aorta and Aortic Arch 379

Descending and Thoracoabdominal Aorta 380

Subject Index 383

Delos M Cosgrove, III, MD

The Department of Cardiothoracic Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio, USA

E Stanley Crawford, MD

Professor of Surgery, Baylor College of Medicine, Houston, Texas, USA Marc R de Leval, MD, FRCS

Consultant Cardiothoracic Surgeon, The Hospital for Sick Children, Great

Ormond Street, London, England

Carlos G Duran, MD, PhD

Chairman, Cardiovascular Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia

Paul A Ebert, MD, FACS

Director, American College of Surgeons, Chicago, Illinois, USA

Roger B B Mee, MD, ChB, FRACS

Director, Victorian Paediatric Cardiac Surgical Unit, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia

Assistant Clinical Professor of Surgery (Plastic Surgery), University of Alabama

at Birmingham, Birmingham, Alabama, USA

Michael Scallan, MB, ChB, FFA(SA), FFARCS

Consultant Anaesthetist, Brompton Hospital, London, England

Jaroslav Stark, MD, FRCS, FACS

Consultant Cardiothoracic Surgeon, The Hospital for Sick Children, Great Ormond Street, London, England

Edward B Stinson, MD

Thelma and Henry Doelger Professor of Cardiovascular Surgery, Stanford University, Stanford, California, USA

James F.N Taylor, MA, MD, FRCP

Consultant Paediatric Cardiologist, The Hospital for Sick Children, Great Ormond Street, London, England

Henry J.C.M van de Wal, MD

Consultant Cardiothoracic Surgeon, Department of Cardiothoracic Surgery, Sint Radboud University Hospital, Nijmegen, The Netherlands

Luis O Vasconez, MD

Professor and Chief, Department of Surgery/Division of Plastic Surgery, The University of Alabama at Birmingham, Birmingham, Alabama, USA

Abbreviations

The following abbreviations occur frequently in the text and as figure labels Less commonly used abbreviations are explained where they occur

ASD Atrial septal defect PFO Patent foramen ova1e

CHF Congestive heart failure PVOD Pulmonary vascular

CVP Central venous pressure RCA Right coronary artery IPPV Intermittent positive RV Right ventricle

pressure ventilation RVOTO Right ventricular outflow

LCA Left coronary artery TAPVC Total anomalous pulmonary venous connection

LVOTO Left ventricular outflow arteries

tract obstruction TV Tricuspid valve

MPA Main pulmonary artery VSD Ventricular septal defect

General

Investigation Before Reoperations for Congenital Heart Disease

J.F.N Taylor

Introduction

The ultimate objective of surgical management

in congenital heart disease is to achieve a

normal systemic output capable of responding

to the increased demands imposed by exercise,

with a normal or near normal pulmonary blood

flow These systemic and pulmonary flows

should be achieved by a myocardium

perfor-ming at its optimum in terms of fibre length,

and rate of shortening

In many congenital cardiac abnormalities,

particularly those with a single anatomical

defect, a single, albeit open, heart operation

allows complete restoration to a normal

circu-latory' pattern The more complex problems

may require more than one intervention, and

a change in both form and function of parts of

the circulation will follow each intervention It

may be essential to establish the magnitude of

these changes and determine their significance

before proceeding to the next stage of a planned

progression to the final normal (or near normal)

circulatory state

Investigation is needed at every stage in this

plan, its thoroughness at an individual stage

being tempered by the initial investigation, and

the likely changes which could have taken place

as a result of the earlier intervention Finally,

there is a place for a detailed haemodynamic assessment of the ultimate definitive surgical intervention This particular investigation serves a dual purpose: firstly, it shows how near is the attainment of a normal circulation This carries a prognosis relevant to the individ-ual patient Secondly, the comparison of the ultimate result of one method of management for a given lesion with another will permit selection of the most appropriate management for future generations

This discussion presupposes that a very detailed haemodynamic study accompanied by

an appropriate imaging technique ography or angiocardiography) will have taken place at some stage before consideration of an open heart operation - not, however, necess-arily immediately before that procedure; the very detailed examination could have preceded the first, palliative, intervention

(echocardi-In considering the place of investigation with relation to operative intervention other than the definitive investigation alluded to above, some form of investigation will be necessary:

1 Investigation between the interventions in

a staged procedure

2 Investigation to evaluate residual intended) lesions

(un-3 Investigation to evaluate changes in status

due to growth, and degradation (e.g

pros-thetic function)

4 Investigation to define the prognosis after

completion of the intended management

5 Ultimate reinvestigation prior to cardiac or

cardiopulmonary transplantation

Staged Procedures

Changes in the pulmonary arterial tree will

be subject to scrutiny following palliative

procedures The imaging technique needed is

usually angiocardiography, as the potential

lesions are too distal for conventional

echocar-diography

Following a systemic-pulmonary anastomosis

it will be necessary to demonstrate that there

has been no distortion to the right or left

pulmonary artery The artery may become

"hitched" up with growth of the child,

particu-larly if a prosthetic implant has been used

between the subclavian and pulmonary arteries

This will obviously retain its implanted length

Distortion leading to uneven blood flow results

from angulation of the pulmonary artery

anas-tomosis, and because of this the right upper

lobe artery is compromised and may no longer

be perfused, especially if the palliation has

been undertaken at a very early age

Some cases of pulmonary atresia with VSD

have a complex arterial supply to the lung:

where, in addition to a supply to some

broncho-pulmonary segments, there may be alternative

or dual supply from arteries originating from

the systemic circulation In such cases a very

important part of the series of investigations is

to demonstrate exactly which

bronchopulmon-ary segments are supplied by the individual

arteries following any shunt procedure or

attempt at unifocalisation (Haworth et al

1981)

Should the continuous murmur of a

pre-viously known functional anastomosis become

inaudible, reinvestigation would be mandatory

to establish whether the pulmonary artery distal

to the anastomosis is still patent, or whether

the occlusion lies within the shunt itself Finally,

should the anastomosis be patent, and a murmur inaudible, it is mandatory to establsh the pressure beyond the anastomosis, as the pulmonary artery pressure may now be at systemic levels

Depending upon the underlying lesion, and the intended ultimate surgical operation, measurement of the pressure within the pul-monary arterial tree and subsequent calculation

of the resistance may be necessary Here it

is pertinent that the pressure measurements should reflect all parts of the pulmonary vascular tree, and it may be necessary to undertake pulmonary arteriography before assessing the pressure in order to attain this objective Discontinuity of right and left pul-monary arteries can be overlooked if visualisa-tion from an aortogram via a natural (e.g duct) and achieved systemic pulmonary anastomosis (e.g modified Blalock-Taussig shunt) give simultaneous and equal perfusion of both pulmonary arteries

Distortion of the bifurcation of the ary artery following banding, with the potential occlusion of one (usually right) pulmonary artery, may occur if the definitive procedure

pulmon-is delayed for several years following the palliation It is also necessary to establish if both arteries are patent and to assess the precise pressure within the two pulmonary arteries, as migration distally of the band frequently leads to uneven flow characteristics, with important consequence in the feasibility

of certain types of correction

Other anatomical features which may change

in an interval between palliation and correction include obstruction below a semilunar valve,

in this context more importantly the aorta Changes in both outflow tracts below the semilunar valves are likely to follow severe obstruction of one, or less severe obstruction

if both outflows are involved by hypertrophy

of the interventricular septum This effect is even more pronounced if the interventricular septum is deviated above a defect (Shore et

al 1982)

There may also be changes in the effective diameter of the bulboventricular communi-cation in various forms of univentricular heart, also leading to effective obstruction of the systemic outflow Changes in relation to the aorta itself may be partly the effect of growth,

e.g following repair of coarctation of the aorta,

or be consequent on the diameter of any

prosthesis becoming disproportionately small

for the increasing body surface area (e.g

prostheses used in abnormalities of the aortic

arch, including interruption)

Haemodynamic changes must also receive

due consideration, particularly where a change

is to be expected as a result of normal

maturation processes (e.g a falling pulmonary

vascular resistance in a neonate with

transpo-sition) or a spontaneous change in the

anatom-ical defect, such as closure of a VSD, or

development of outflow obstruction, which is

more likely with discordant ventriculo-arterial

connection (Freedom 1987)

The extent of the investigation prior to

definitive operation following a palliative

pro-cedure will depend on the extent of potential

changes, the timing interval between the two

procedures, and the detail of the first

investi-gation Full haemodynamic assessment is

prob-ably necessary if more than two years have

elapsed since the earlier assessment This is

much more important if, at any time,

pulmon-ary blood flow has been in excess of systemic

blood flow Cognisance should also be taken

of ventricular function, though whether this is

achieved by echocardiographic or

angiocardio-graphic means, separately or in combination,

will depend upon individual circumstances The

advent of accurate Doppler techniques and

colour Doppler flow mapping means that more

of the information needed is becoming available

from non-invasive studies

If a detailed non-invasive study is not

under-taken prior to an open heart operation following

a palliative procedure, there must be available

supportive clinical and non-invasive evidence

that the haemodynamic status and anatomical

lesions have not been adversely affected in the

interim, and any specific expected or potential

change must be positively demonstrated

Residual Lesions

This section will concentrate on the

investi-gation of problems arising immediately after

surgery, most commonly whilst the patient

is in the intensive care unit, and certainly recognised before discharge from hospital

Clinical Considerations

Following open heart surgery ventilation is always employed in the immediate postoperat-ive period At this time catecholamine support and afterload reduction commonly supplement fluid and volume replacement At times main-tenance of a higher or at least stable cardiac rate may be achieved by use of an external pulse generator system Intrapleural and intra-pericardial drainage tubes may be in place Under these conditions the presence of a significant residual haemodynamic lesion will not be revealed by the same time-honoured manner of physical examination leading to progressively detailed investigation that has been employed in the preoperative assessment

It is the failure of the usual progressive improvement in a particular aspect of patient care which gives the clue to a residual lesion, and to the need for further investigation After a simple open heart procedure it may

be possible to extubate the patient in theatre,

or soon after returning to the intensive therapy unit However, 2 or 3 days of full ventilation may be necessary following a complex repair, and low flow cardiopulmonary bypass so that if there is any mild associated aortic regurgitation this will be minimised at flow rates of 500 750 mVmin The aorta is never dissected, cardio-plegia is not used and the heart usually arrests

at that low temperature With the flaccid heart good exposure is excellent Whatever is necess-ary for surgical reconstruction of the annulus and placement of the prosthetic or biopro-sthetic valve is then carried out When the valve prosthesis is inserted ·a red rubber catheter is placed through the valve to keep it incom-petent The left atrium is then closed; the pati-ent is placed in a head-down position and slightly rotated to the left so that the left atrium would be in the highest position Careful de-airing is then carried out The patient is sub-sequently weaned from cardiopulmonary bypass after closure of the left atrium is com-pleted For details of the approach see Chapter

4 (p 43), and for further details about mitral valve surgery, Chapter 24 (p 325)

addition its ventricular wall has been the subject

of fibrotic change A left to right shunt as little

as 1.5:1 is not tolerated; cardiac performance

is maintained at the expense of considerable

inotropic support, maintenance of a normal

blood gas and acid-base status is not possible

without full ventilatory support, and there

are copious, but not usually thick pulmonary

secretions Any residual obstruction within the

right ventricular outflow or in the pulmonary

arterial tree will impede further progress

A similar clinical picture will be produced

if mitral regurgitation persists, or suddenly

develops from a breakdown in the repair In

contrast to a left to right shunt, however, minor

degrees of regurgitation are tolerated, and it

is only the severe degrees which preclude a

good postoperative progression The more

common problem related to the repair of

AVSD, where the clinical picture more closely

follows the pattern of a residual VSD, is not

pure mitral regurgitation, but a left ventricle

to right atrial shunt

There may also be a shunt pre~ent at great

artery level This may be an unrecognised

ductus, or an aortopulmonary communicating

artery in cases of diminished pulmonary blood

flow It should be remembered that a ductus

may be missed even with a scrupulous

preoper-ative study if pulmonary and systemic resistance

approximate It can be difficult to recognise

that there is a defect in the position of a ductus,

even with direct aortography, unless the arch

is ideally profiled, and a high film frame

speed is used Therefore, echocardiography

supplemented by Doppler techniques may be

superior It would be unusual for

aortopulmon-ary communicating arteries to be unrecognised,

but the magnitude of their contribution to

pulmonary blood flow may be underestimated

(Additionally during the postoperative

investi-gation they may be embolised, avoiding a

further operation.)

Another clinical pattern suggesting a residual

left to right shunt emerges at the end of the

first postoperative week Progressive decrease

in ventilatory requirement and inotropic

sup-port in the early days suggest an encouraging

result, and then, without evidence of a

superim-posed respiratory infection, there is a rapid

increase in ventilatory requirements, together

with a need for inotropic support Increased,

often watery pulmonary secretions accompany this phase This picture is also seen after banding the pulmonary artery in small infants with very complex malformations in whom complete repair is not feasible The probable explanation, here and after attempted correc-tion, is that pulmonary vascular resistance is sufficiently high in the first 3-4 postoperative days that this shunt is of little import, but its magnitude increases dramatically as the pulmonary resistance falls during the latter part

of the first postoperative week

Following some repair procedures for plex lesions involving transposition or other malpositions of the great arteries, the impor-tance of any left to right shunt is also influenced

com-by the potential for obstruction below the aortic valve; a gradient of more than 10 mmHg between the body of the subaortic ventricle and the aorta may be a significant additional disturbance to the left to right shunt Such an effect may also be seen following repair of the more severe forms of A VSD

Infants, particularly those who have failed

to thrive, may suffer episodic rises in pulmonary artery pressure to suprasystemic levels, with a concomitant fall in systemic output The infants particularly at risk are those in whom a high pulmonary blood flow preoperatively has been associated either with a degree of obstruction

to pulmonary venous return, or with an elevated level of calculated pulmonary arteriolar resist-ance It is necessary to demonstrate that there

is no residual left to right shunt present, and that pulmonary venous drainage is free through

to the systemic ventricle A trigger mechanism for these pulmonary hypertensive crises may

be pulmonary venous desaturation The gerated response which leads to the crisis includes a rapid rise in pulmonary arterial pressure, which soon exceeds the falling sys-temic arterial pressure Systemic output falls, though the systemic venous pressure may still continue to rise as the elevation of the pulmonary resistance precedes the fall in the systemic output Arterial saturations will be low, and the fall in oxygen delivery to the tissues will be exacerbated by the low forward flow to give a progressive acidaemia This

exag-is associated with hypercapnia, as the poor pulmonary blood flow precludes adequate gas exchange The peripheral circulatory failure

will be accompanied by a falling peripheral,

and rising central temperature

Persistent cyanosis is not invariably the result

of ventilation perfusion inequality in the lung

A small number of fairly well-circumscribed

lesions, notably incomplete relief of obstruction

to right ventricular outflow, associated with

small residual ventricular or atrial

communi-cations, can give intense desaturation The

degree of obstruction must be severe, and,

whilst unusual following repair of a Fallot-type

situation, it may result if a conduit is used

between ventricle and pulmonary artery

Com-pression from the closed sternum on the conduit

itself or distortion at either anastomosis will

produce a high resistance to flow through that

conduit This rather than a malfunction of any

valve mechanism within the conduit is the more

usual reason for impaired right ventricular

function

A right to left shunt at atrial level, in the

presence of a residual defect or an open

foramen ovale, can occur if the end-diastolic

pressure in the right ventricle is elevated - from

intrinsic failure of the right ventricular

myocar-dium, or from unrelieved obstruction An

unrecognised anomaly of systemic venous

return, e.g the so-called unroofed coronary

sinus, may give persistent cyanosis but with

an otherwise good cardiac performance The

misdirection of inferior vena caval blood to the

left atrium during repair of certain types of

ASD is well recognised

Any problem following the Fontan procedure

demands careful attention, as it may result

from a residual shunt in either direction or a

degree of obstruction to flow into the

pulmon-ary circulation If the pulmonary trunk is

undivided and the proximal pulmonary artery

is not perfectly closed at its origin it may be

possible for left ventricular blood to continue

to enter the pulmonary circulation Although

quantitatively this may not be a large shunt, it

will increase the pulmonary artery pressure,

and therefore the impedance against which the

right atrium is functioning, and may well exceed

its level of tolerance A right to left shunt will

follow any breach, however small, in the

interatrial septum; this occurs particularly in

the modifications of the original procedure used

to repair essentially double inlet univentricular

hearts, if the tricuspid orifice is not sealed

completely An uncommon but ically very significant shunt may occur through the coronary sinus if this has an unusually free communication directly to the left atrium through the Thebesian system

haemodynam-An unobstructed communication between right atrium and pulmonary artery is a critical factor in maintenance of right atrial function following the Fontan procedure If for either

of these reasons forward flow falls so low that significant systemic hypotension results, systemic venous return may also be so low that the signs of systemic venous congestion - a high central venous pressure, hepatomegaly, and oedema - do not develop A similar clinical picture was at one time seen after Mustard's operation if all venous return pathways were narrowed (Silove and Taylor 1976) It has not been seen with the Senning operation, though

a raised venous pressure must be interpreted

in the light of the overall cardiac output when assessing the severity of any obstructive lesion involving the total systemic venous return After the first few days it may become apparent that a murmur is present but its recognition is not crucial to the assessment

of a residual lesion It may be difficult to differentiate a pansystolic murmur from an ejection murmur in these circumstances, and dangerous to infer the lesion responsible for the murmur The presence of a mid-diastolic murmur still implies a large shunt at this time; its absence certainly does not indicate that the shunt is insignificant Early diastolic murmurs are always important if thought to originate from the aorta A soft early diastolic murmur from the pulmonary trunk is common after repair of Fallot's tetralogy, and one is more often heard than not when a valved conduit is used between the ventricle and pulmonary artery; these murmurs do not necessarily imply

a major residual defect

The clinical features suggesting a residual lesion are summarised in Table 1: 1 In the presence of one or a number of these features increasingly detailed investigation should be undertaken in order to reach two conclusions:

1 Is there a residual lesion?

2 Is it of such haemodynamic severity that the clinical management should be changed, e.g reoperation?

Table 1.1 Signs suggestive of a residual cardiac lesion

1 Persistent ventilatory requirement

2 Continued dependence on inotropic support

3 Increasing cardiac failure and/or low cardiac output

4 Arterial de saturation without pulmonary cause

5 The appearance of a loud murmur

6 Recurrent supraventricular tachycardias

A combination of the following investigations

will usually produce the answer

Non-invasive Investigation

Electrocardiography

Arrhythmias may complicate both the

short-and long-term course following operation

Whilst it is seldom necessary to investigate the

arrhythmia by electrophysiological studies in

the short term, some general and, in particular,

haemodynamic problems should be considered

and the appropriate investigation undertaken

to determine their presence, even if the only

clinical sign is a persistent (and therefore simple

drug-resistant) arrhythmia

Administration of sufficient potassium

sup-plementation to correct any whole body deficit

is also an adjunct to management, as is the

correction of any anaemia; the haemoglobin

level should be maintained at 12.0 g/l00 ml or

above under these circumstances The

appropri-ate haemodynamic or echocardiographic

evalu-ation should then be undertaken to determine

if any of the following possibilities are relevant:

1 Pericardial fluid

2 Localised thrombus behind the heart

3 Major left to right shunt

4 Raised intra-atrial pressure for whatever

cause (left or right)

5 Irritation from indwelling intracardiac

monitoring line, or extracardiac drain

6 Sepsis elsewhere, particularly blood borne

Bradycardia profound enough to require use

of the pulse generator system more usually

results from the direct surgical interference

with the conducting tissue to produce heart

block However, the sudden late appearance

of heart block, or widening of the QRS complex (bundle branch block) would suggest that some intracardiac mechanical event, involving the atrioventricular node or the bundle of His, has occurred

Chest Radiography

It is important to exclude a localised pulmonary abnormality as the cause for continued ventila-tory dependence or cyanosis However, wide-spread changes suggesting patchy consolidation may be related to pulmonary oedema, either with high flow, or pulmonary venous conges-tion The presence of a pleural effusion will in itself impair ventilation, but bilateral effusions would certainly suggest a cardiac cause The overall size of the cardiac silhouette needs careful interpretation In the presence

Fig l.la

Fig l.lb

of positive pressure ventilation the heart size

does not accurately represent the volume load

on the heart - a high pulmonary blood flow

may be present with a small cardiac silhouette ;

it is worth disconnecting the patient from the

ventilator for 30 45 s before exposing the

radiograph to obtain a representative

im-pression Figure 1.1 shows the difference in

heart size on intermittent positive pressure

ventilation (Fig 1.1a) and while breathing

spontaneously (Fig Lib) Figure Lib shows

a chest radiograph taken a few hours after

Fig 1.1a, when the patient was breathing

spontaneously without any increase in

expira-tory pressure The heart has dilated and

pulmonary vascular markings are more

promi-nent, reflecting the increased pulmonary blood

flow Cardiac catheterisation confirmed a

sig-nificant shunt at ventricular level

Fig 1.2a

Fig 1.2b

A large cardiac silhouette, even when the patient is disconnected from the ventilator, especially if a pleural effusion is also present, would imply fluid and/or blood clot within the pericardial sac Even if the pericardial sac is left open at operation, accumulation behind the heart can occur An enlarged, or enlarging cardiac silhouette in the presence of a falling systemic output and rising venous pressure can mean tamponade However, the investigation

of choice for pericardial fluid is phy; for this purpose it is simple, reliable and readily repeatable Figure 1.2a shows an echocardiographic four-chambered view and Fig 1.2b a short axis view in a patient with pericardial effusion (PE) Effusion was present both posterior and anterior to the heart Paralysis of the diaphragm, particularly if bilateral, may be missed on routine radiographs taken with the patient ventilated As the heart size can be increased if the diaphragm tends to remain high, a cardiac cause of the persistent ventilatory dependence may be sought Screen-ing under fluoroscopy is most helpful; however,

echocardiogra-if this is dechocardiogra-ifficult in the intensive care situation,

a radiograph taken with the patient nected from the ventilator may show persistent elevation of one half of the diaphragm, with mediastinal shift It is also possible to identify the diaphragm and visualise the pattern of movement echocardiographically

discon-Pleural Effusion

Whilst local pulmonary problems may produce pleural effusion, possible causes include cardiac failure, particularly if associated with pulmon-ary venous congestion and more probably if the effusions are bilateral There are two other conditions which should be considered and will need differentiation at the ensuing investigation - any cause of elevated venous pressure consistently above 20 mmHg will impair drainage from the thoracic duct, and lead to accumulation of lymph and/or chyle within lungs and pleural cavity Superior vena caval pathway obstruction either after intra-atrial repair of transposition, if the inferior vena caval pathway or the azygos connection

is compromised, or following the Fontan cedure, are the two most usual causes in current

pro-practice The alternative is surgical interruption

of the thoracic duct somewhere along its

mediastinal course, in which case there will be

no untoward haemodynamic findings; however,

this procedure may be associated with

accumu-lation of fluid within the pericardium sufficient

to cause tamponade

Echocardiography

From the foregoing it is clear that

echocardiog-raphy has a rightful place in the intensive care

unit It is the examination of choice for the

presence of pericardial fluid It is extremely

useful in providing another measure of

ventricu-lar performance Figure 1.3 shows the

cross-sectional (Fig 1.3a) and "M"-mode (Fig 1.3b)

echocardiogram from a patient with poor left

ventricular function The left ventricle (and to

a lesser extent the left atrium) are dilated, and

Fig 1.3a

there is little change between end-systolic and end-diastolic dimension, as shown on both the two-dimensional and "M"-mode displays (IVS, interventricular septum) Changes in manage-ment and particularly changes arising from drug intervention can be assessed semi-quanti-tatively

The use of echo cardiography for screening the diaphragm has been discussed Turning to the possible intracardiac lesions, echocardiogra-phy is not as useful in the postoperative period

as during preoperative assessment This is partly due to inferior image quality The operative intervention itself alters the acoustic quality of the tissues surrounding the heart, and reduces the acoustic window Furthermore, access for the transducer head is limited by the various chest drains, the pacing wires and the incision itself

Although the provision of intravenous and left atrial lines means that contrast echocardiog-raphy may be easily undertaken, unfortunately

it does not answer the question posed by the clinician, i.e how significant is a residual shunt? The problem is that bidirectional shunting is almost always demonstrated by microbubble echocardiography in the period immediately following open heart repair The additional information provided by Doppler studies will

so supplement the visual information that some form of quantitation becomes possible One can deduce pressure differences between the ventricles, if there is concern that a significant ventricular shunt remains, and clearly both stenotic and regurgitant valve lesions may be identified with greater precision

Invasive Investigation

Cardiac Catheterisation

Moving an infant or child from the intensive care unit to the cardiac catheterisation labora-tory is not a task to be undertaken lightly, but provided a complete study is undertaken the information obtained always aids management, whether or not the expected lesion is demon-strated

The most likely lesions have been described Fig 1.3b above However, as the unexpected does occur,

each catheterisation study should be complete

within itself, and leave no questions concerning

the morbid physiology unanswered Whilst the

routine to be followed in the laboratory will

follow the pattern laid down for the detailed

investigation of any patient with congenital

heart disease, there are a number of special

points The patient will of necessity be

intu-bated and ventilated The inspired gases will

be oxygen enriched and an FI02 of 0.4,0.6 or

even 0.8 is needed frequently It is important

to check the pulmonary vein P02 early in the

study (or its closest approximation, e.g the

arterial) and to adjust the inspired oxygen

concentration to achieve full saturation, or a

P02 in excess of 90 mmHg, even if it means

increasing FI02 to 1.0 Unless full pulmonary

vein saturation is achieved, no meaningful

assessment of the magnitude of a shunt or

calculations of pulmonary blood flow can be

made by the Fick principle In the presence of

an intracardiac right to left shunt it will

be necessary to sample the left atrium or

pulmonary vein directly By the nature of the

postoperative lesion likely to be present this is

not usually difficult: it is because there is

residual patency of the atrial septum (more

common in practice than that of the ventricular

septum) in the presence of a raised resistance

to pulmonary ouflow that such a shunt exists

Determining whether there is a pulmonary

component to the cyanosis, or whether this is

associated with a residual lesion, is of course

one of the fundamental reasons for early

postoperative investigation

It is important to detect even the smallest

left to right shunt at the time, and shunt sizes

as little as 1.3-1.5:1 may be highly significant

The actual shunt size must be evaluated in

relation to the pulmonary artery pressure and

to the diffusion gradients across the alveolar

membranes, i.e related to the FI02 level

needed to achieve full pulmonary venous

saturation The relative effect on a shunt of

the increased end-diastolic pressure in both

ventricles needs consideration In the final

assessment the shunt size must also be

corre-lated with the anatomical lesion delineated by

angiocardiography

Other methods of estimating shunt size and

overall function of the circulation may give

additional help When high inspired oxygen

concentrations are needed because of the impaired pulmonary function, dye dilution methods may be appropriate Thermodilutions may be practical in the intensive therapy unit, and if good echocardiographic images are available they obviate the need for a full catheterisation procedure The technical con-siderations for obtaining high-quality curves

to analyse remains, and in these particular circumstances may be enhanced by the rela-tively poor ventricular performance (Lock 1987)

The pressure measurements taken at cardiac catheterisation should be taken from all four chambers, and reference to the arterial pressure made throughout This is usually very easy as

at this stage an indwelling arterial line is required for immediate management in the intensive care ward The pulmonary artery pressure should be ascertained more than once during the course of the investigation, and certainly needs to be reassessed with any deliberate change in ventilation, or in FI02 •

Finally, it should be established that there is

no gradient between the body of the right ventricle and the main branch pulmonary arteries, nor between the body of the left ventricle and the aorta (the descending or abdominal aorta if the operation involved the distal arch)

If the patient will breathe spontaneously for even as short a time as 1 min, two observations are worthwhile during such a period The first

is to visualise the diaphragm fluoroscopically

to ensure normal movement of each half of the diaphragm is present Secondly the variation

in both arterial and venous pressure with respiration is assessed to exclude any restriction

by the pericardium or its contents An vation will have been made during the preced-ing oximetric and manometric study that the catheter does reach both heart borders The point will finally be checked by angiocardiogra-phy

obser-Any abnormal catheter course should be noted as this provides direct evidence of a communication between the two sides of the heart, though it does not give a measure of size It is worthwhile to undertake a careful withdrawal pressure trace to a predetermined reference point (usually the right atrium) as this may be the only clue to the level of a

potential obstructive lesion in relation to the

residual interventricular or interatrial defect

under consideration The question of

retro-grade catheterisation of the aorta, and the

ventricle beneath the aortic valve will depend

on the need to assess the presence of a

pressure difference across the aortic valve or

the subvalve region and the need for an

angiocardiogram which cannot be performed

with the per-venous catheter, by passage across

a defect It may therefore be necessary to enter

the sub aortic ventricle for at least one of these

reasons

Angiocardiography

As with any preoperative investigation the site

and number of contrast injections to be made

will depend on the clinical circumstances and

haemodynamic findings In general the quality

of angiocardiograms taken at this time is

inferior to those obtained in the preoperative

or late postoperative period There are a

number of reasons for this, but the two most

cogent are (1) the interference from other

intravenous catheters, drains, pericardial wires

etc., and the relative radiographic density

change between lung and heart; and (2)

the less efficient ejection of both ventricles

However, the golden rule of angiocardiography

remains: to deliver the contrast medium (an

adequate amount in less than 1.5 s)

immedi-ately "upstream" of the lesion to be

demon-strated

Consideration may be given to the total

volume of contrast medium to be used as it is

in itself a strong diuretic, and dosage should

be judged in relation to the patient's current

renal function, the current fluid load, and the

diuretic management in use However, given

a liberal choice, the contrast medium

require-ment will be similar to that needed to

demon-strate a comparable haemodynamic lesion in

the preoperative period

Do not cut short the laevo phase, even if

left ventriculography is contemplated There

will be much useful information not necessarily

duplicated (e.g pulmonary venous drainage

and left atrial size, and ventricular performance

in the absence of extra systoles) All

angiocardiograms taken in the postoperative

period should be evaluated for the presence of pericardial fluid and for ventricular perform-ance, over and above the particular lesion under scrutiny A careful review of the four cardiac chambers, both great arteries, and the systemic and pulmonary venous return pathways should be undertaken, and reviewed

in the light of the haemodynamic findings The importance of aortography in the light of the clinical and therefore elucidated haemodynamic findings needs consideration in view of the objective to obtain all relevant information Aortography will enhance the differentiation

of a ventricular from a great artery shunt; it will enable visualisation of the coronary arterial system, and assess competence of the aortic valve itself Furthermore, an obstructive, or potentially obstructive lesion within the intra-thoracic part of the aorta will be visualised fully It is important to ensure that the plane

of the nominal antero-posterior projection is sufficiently oblique (left anterior oblique about 30°) to keep the descending aorta clear of the aortic valve, to allow interpretation of the movements of the valve mechanism itself The salient features for investigation by cardiac catheterisation and angiography are summar-ised in Table 1.2

Table 1.2 Watch points for postoperative cardiac ation and angiocardiography

catheteris-Postoperative cardiac catheterisation

1 Correct any pulmonary venous desaturation

2 Determine if any left to right shunt and its magnitude

3 Determine if any right to left shunt and its magnitude

4 Ensure a) no pressure gradient right ventricle to pulmonary artery

b) no pressure gradient left ventricle to aorta

5 Check no gradient between pulmonary capillary wedge pressure and left ventricular end-diastolic pressure

6 No systemic venous pathway obstruction

7 Exclude constriction within pericardial cavity

Postoperative angiocardiography

1 Delineate site( s) of any shunt (in either direction)

2 Define anatomical substrate of any pressure gradient

3 Demonstrate if any a) atrioventricular valve regurgitation b) aortic regurgitation

4 Semiquantitative assessment of ventricular function

5 Exclude pericardial effusion

Summary

Postoperative haemodynamic and

angiocardio-graphic study should be undertaken if the

patient fails to follow the expected pathway of

progress to an improved clinical state following

operation While the investigation will aim to

demonstrate the nature and severity of the

residual lesion, it should also be sufficiently

wide ranging to encompass any additional

defect not anticipated from the clinical findings

Recurrent Lesions

Later realisation that a residual/recurrent lesion

may be significant will lead to investigation

after the patient has left hospital, as will

unexpected changes in the physical findings

during any follow-up period These problems

fall into four broad categories:

1 A residual/recurrent intracardiac shunt,

usually at ventricular level It would be unusual

for such a shunt to develop after the first

postoperative week, but a later fall in the

pulmonary vascular resistance may result in an

increase in the shunt and so induce cardiac

failure Failure to recognise the magnitude of

shunt through one aortic collateral to the lungs

may also occasionally cause late cardiac failure

Right to left shunts do not present late,

unless resulting from increasing obstruction to

pulmonary outflow in the presence of a residual

septal defect

2 Atrioventricular or semilunar valve

regur-gitation may be present from the time of

operation, but inadequate clinical progress will

reveal a need for early evaluation with a

view to further procedures This will apply

particularly to any residual deficiency following

repair involving the mitral valve, and following

repair in lesions with a dilated aortic root The

degree of aortic regurgitation may alter, or not

have been fully assessed preoperatively The

older patient with Fallot's tetralogy or

pulmon-ary atresia with VSD falls into this group;

patients with truncus arteriosus are at risk

3 Obstructive lesions to either ventricular outflow

a) Obstruction to pulmonary flow The

major problem here results from plete relief of stenosis at the bifurcation

incom-of the pulmonary artery, incomplete relief of hypertrophied infundibular obstruction, particularly immediately below the pulmonary valve ring, and conduit obstruction This results either from pressure on the whole conduit by its position in relation to the sternum

or from anastomotic narrowing b) Obstruction to outflow from the left ventricle Obstruction may develop

below the aortic valve in a number

of complexes It may follow previous resection of hypertrophied muscle, or may follow previous closure of mal-alignment VSD, particularly if there was posterior displacement of the infun-dibular septum Patients with the coarc-tation or mitral valve anomalies which fall into part of the Shone syndrome complex are also at risk of developing subaortic obstruction Finally, a long intracardiac tunnel used to direct left ventricular outflow to an anteriorly placed aorta may develop obstruction

at the site of the original ventricular septal defect, even if this has been enlarged Incomplete relief of either coarctation or stenotic lesion involving the mitral valve apparatus and the supravalvar region may result in earlier deterioration than anticipated

4 Lesions reSUlting from the technique of cardiopulmonary bypass Cognisance should be taken of the fact that a group of lesions may occur which result from the procedures common to all open heart operations Mention has already been made of the early problem

of diaphragmatic paralysis following injury to the phrenic nerves, and damage to the liver and inferior vena cava from cannulation may occur Vena caval pathway narrowing may result from inappropriate placement of cannu-lae Clearly there may be many individual problems which cannot be predicted, so that the investigation must always take account of

an unexpected finding or one that may not

Fig 1.4

accord with the physical findings Figure 1.4

depicts such a lesion Following repair of an

aortopulmonary window the child developed

the murmur of aortic stenosis, but the lesion

responsible for the signs was a supravalvar

stenosis at the aortic cannulation site

Changes Resulting from Growth,

and Deterioration in Prosthetic

Function

Many major and corrective procedures are

undertaken in infants and small children, whose

subsequent growth potential means that there

will be a three- or fourfold change in vessel

diameter before adult stature is attained Any

differential in capacity for growth resulting

from surgery will produce an effect years after

an early satisfactory result

Procedures involving arterial anastomoses,

particularly of the great arteries, are at risk,

so that continued follow-up for all lesions into

adult life must be maintained The incidence

of late recoarctation more usually, but not

exclusively, following end-to-end anastomosis

results from inequality of circumferential

growth, clearly inevitable if non-absorbable continuous sutures were employed, but not completely avoided by use of another material (Campbell et al 1984) The same strictures may occur to both pulmonary arterial and aortic anastomoses after the arterial switch procedure for transposition of the great arteries (Yacoub et al 1982)

arterial anastomoses of the classic Taussig procedure are largely avoided by use

Blalock-of a prosthetic implant (de Leval et al 1981), but as such management is now rarely definitive from an early age, this consideration is no longer of practical import However, care should be taken with any procedure which relates to venous inflow as, on occasion, the anastomosis created between the pulmonary venous confluence and the left atrium in total anomalous pulmonary venous drainage may become restrictive after a number of years Obstruction in both systemic venous and pul-monary venous pathways following rearrange-ment of atrial flow for transposition of the great arteries where there has been extensive use of prosthetic material may occur as a late problem

However, numerically one of the major problems in the long-term management of children with congenital heart disease is, the function of valve-containing conduits, particu-larly of those leading to the pulmonary circu-lation This problem falls into three com-ponents, not necessarily separable from each other, but which in combination lead to a deterioration in conduit function in a disap-pointingly short time (Bull et al 1987) The components are:

1 Conduit size, related to patient's growth

2 Deterioration of cusp function

3 Peel formation

The changes related to growth are of course predictable, and it would seem that valve-bearing conduits inserted in infancy will cause significant obstruction in about 5 years assuming normal growth, even though the conduit at its insertion contained a valve of

valve would have had for the infant's body surface area Changed at above 5 years of age

one would expect adequate function in terms

of size alone over at least the next decade

Deterioration of valve function does seem

to bear some relation to the child's age, with

late childhood and early adolescence being

times of major hormonal and anabolic activity,

which could enhance the rate of degenerative

change Cusp function deteriorates from

thick-ening of the whole surface, commissural fusion

and degeneration to result in a fixed orifice; it

becomes restrictive and regurgitant This series

of changes appears to take place in both

homograft and heterograft semilunar valves

The rate of degeneration in the homografts is

influenced by the method of preparation and

length of storage (Stark 1988)

Finally, the obstruction may be compounded

by the presence of "peel": concentric layers of

thrombus and fibrin deposits within the conduit,

both up- and downstream of the valve itself

It would appear that this process occurs only in

segments of woven Dacron interposed between

the ventricle and valve or the valve and the

pulmonary artery

Sometimes the total obstruction afforded by

the conduit is added to by true narrowing at

the site of either proximal or distal anastomosis

Narrowing of the proximal anastomosis will be

progressive if there is muscle hypertrophy just

below the suture line

In clinical terms conduit function should

be monitored closely, and assessment of the

gradient between the ventricle and pulmonary

artery made at least biannually The sudden

reappearance of effort intolerance,

enhance-ment of the murmur, and possibly appearance

of a thrill all suggest increasing obstruction at

the conduit Additional signs will be given

by increased right ventricle voltages on the

electrocardiogram, and changes in the right

ventricular parameters assessed

echocardio-graphically It may be difficult to visualise the

conduit wall, and this contributes to the

difficulty of accurate Doppler interrogation in

these circumstances This might lead to an

underestimate of the maximal velocity into the

pulmonary circulation Hence serial changes in

right ventricular size and in wall thickness are

important secondary changes which should be

interpreted critically, in the light of the serial

Doppler measurements If there is any doubt,

or unresolved discrepancy, precise pressure

measurements should be taken at cardiac catheterisation

Prognosis After Completion of Intended Management

Objectives of treatment of congenital heart lesions include restoration of a normal circulat-ory pattern, capable of responding to the demands of exercise, maintaining normal ven-tricular function, and keeping the pulmonary vascular resistance within the normal range

To a considerable extent these objectives are interrelated, but the assessment of change in the pulmonary vascular resistance is least open to clinical or non-invasive assessment However, it will have a major influence on the long-term prognosis for the patient, so that there is a very real reason for suggesting a detailed postoperative assessment after 5 or more years following even the most successful clinical outcome of an open-heart procedure Such an assessment may include cardiac cath-eterisation, with appropriate flow measure-ments by Fick or other dilution methods in order to calculate the resistances, but it should ideally include a measure of exercise capacity,

an estimate of homogeneity of myocardial perfusion, and a study of any potential for arrhythmia

To the individual patient such a detailed reassessment will give reassurance about the future, and an understanding of what real physical achievements are to be expected It

may be necessary information for social security reasons, life assurance applications and the like However, it does serve another fundamental purpose: when the results from a group are analysed, on the basis of the objective data, it will become possible to distinguish which form

of management in infancy yields the most beneficial long-term results, measured not by survival alone but by function

Assessment late after intervention (more than 5 years) in certain lesions has indicated the beneficial effect of earlier intervention on the subsequent development of arrhythmias (Sullivan et al 1987) It is postulated that there would have been less damage to the

myocardium, and this may need to be shown

in terms of perfusion studies (radioisotope

uptake) or in vivo metabolic studies (magnetic

resonance and positron tomographic

tech-niques)

It is also evident that an objective measure

of circulatory performance must now be

included in any worthwhile long-term study

Subjective assessment of effort tolerance

al-ready gives an underestimate of the athletic

abilities of children following repair of complex

congenital cardiac deformities (Stark et al

1980) It is also necessary to evaluate the

pulmonary response, as the changes consequent

on the early and prenatal disturbance of blood

flow are not always corrected by repair of the

cardiac lesion, even early in infancy

Conclusion

Congenital heart disease is dynamic; there are

rarely, if ever, "fixed" lesions After major

operative intervention there still remains the

potential for change, be it early or late after

such intervention Therefore, any change in

the clinical condition, or, equally important,

any failure to progress as expected, demands

detailed and complete investigations The

man-agement of the individual patient, or the

management of all patients with that lesion,

may need to be changed in the light of the

findings to improve the duration of good

cardiovascular performance Reliable,

repeat-able and non-invasive assessment of both form

and function, even a decade after initial

management, will benefit the individual patient

and the future generation of those born with

a malformed heart

References

Bull C, Macartney Fl, Horvarth P et al (1987) Evaluation

of long-term results of homograft and heterograft valves

in extracardiac conduits 1 Thorac Cardiovasc Surg 94: 12-19

Campbell DB, Waldhausen lA, Pierce WS, Fripp R, Whitman

V (1984) Should elective repair of coarctation of the aorta

be done in infancy J Thorac Cardiovasc Surg 88: 929 938

de Leval' MR, McKay R, Jones M, Stark l, Macartney

Fl (1981) Modified Blalock-Taussig shunt 1 Thorac Cardiovasc Surg 81: 112-119

Freedom RM (1987) The dinosaur and banding of the main pulmonary trunk in the heart with functionally one ventricle and transposition of the great arteries: a saga of evolution

and caution 1 Am Coli Cardiol 10: 427-429

Haworth SG, Rees PG, Taylor lFN, Macartney Fl, de Leval

M, Stark J (1981) Pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries Effect

of systemic pulmonary anastomosis Br Heart J 45: 133-141 Lock JE (1987) Haemodynamic evaluation of congenital heart disease In: Lock JE, Kean JF, Fellows KE (eds) Diagnostic and interventional catheterisation in congenital heart dis- ease Martinus Nijhoff, Boston, pp 33-62

Shore DF, Smallhorn J, Stark J, Lincoln C, de Leval MR (1982) Left ventricular outflow tract obstruction, co-existing with ventricular septal defect Br Heart J 48: 421-427 Silove ED, Taylor JFN (1976) Haemodynamics after Mustard's operation for transposition of the great arteries

Br Heart J 38: 1037-1046 Stark J (1989) Do we really correct congenital heart defects?

J Thorac Cardiovasc Surg 97:1-9 Stark J, Weller P, Leanage R et al (1988) Late results of surgical treatment of transposition of the great arteries In: Vogel M (ed) Advances in Cardiology, vol 27 Karger, Basel, pp 254 265

Sullivan ID, Presbitero P, Gooch VM, Aruta E, Deanfield

JE (1987) Is ventricular arrhythmia in repaired tetralogy

of Fallot an effect of operation or a consequence of the course of the disease? A prospective study Br Heart J 58: 40-44

Yacoub MH, Bernhard A, Radley-Smith R, Lange P, Sievers

H, Heintzen P (1982) Supravalvular pulmonary stenosis after anatomic correction of transposition of the great arteries: causes and prevention Circulation 66: 193-197

Investigations Before Reoperation for Acquired Heart Disease

Celia M Oakley

Introduction

Cardiac operations are often not curative

Reoperation is not infrequent in coronary and

valvar disease The mortality of reoperation in

most centres is higher than for first operations,

particularly for valve re-replacement, and the

results are less good, especially after redo

coronary artery bypass grafting (Jett et al

1986; Nakano et al 1986; Gautam et al 1986)

The indications have to be considered therefore

with great care and in as full as possible

understanding of the reason for the poor result

of the first procedure

Symptoms are often unreliable, and the

physical signs difficult after previous

conserva-tive valve surgery or valve replacement They

are usually unhelpful in coronary disease,

although failure to examine the patient carefully

may lead to postoperative pericardial

constric-tion being missed Supportive investigaconstric-tions

are usually necessary and can often be entirely

non-invasive unless coronary angiography is

needed

Methods of Investigation

Non-invasive Investigation

Exercise testing should be a regular routine

following coronary bypass surgery, regardless

of symptoms, because it provides easy, safe, inexpensive, reliable and objective means of recording the postoperative result It is also useful in patients with valve disease, especially those who report disability which seems unex-plained and may be attributed to underlying coronary disease It provides the best measure

we have of exercise capacity, especially if maximal oxygen uptake (MV02 ) is measured, but short of that it shows what the patient can

or is willing to do and what he considers to be

a tolerable or unacceptable exercise ance It can reveal unexpected locomotor disability or asthma which may have been wrongly attributed to the heart or simply a poorly controlled ventricular rate in atrial fibrillation

perform-Exercise echocardiography is now proving a more convenient, sensitive and repeatable means of detecting exercise-induced regional wall motion abnormalities in coronary patients than nuclear left ventricular blood pool scan-ning (Robertson et al 1983; Heng et al 1985) Exercise with thallium myocardial scintigraphy has always been a disappointment because of poor resolution, and we believe there are now few indications for it

Cross-sectional echocardiography with Doppler measurements of gradient, and often colour flow guided, gives more information about valve anatomy and function (Fig 2.1), the characteristics of the left ventricle, regional wall thickness and movement than angiocardi-ography Figure 2.1 shows long axis (on the left) and short axis views of the left ventricle

from an older patient with mitral valve disease

and previous mitral valvotomy The mitral

valve shows the typical rheumatic changes with

thickening mainly at the points of contact of

mitral leaflets The combination of anatomical

and functional characteristics often leaves little

need for cardiac catheterisation for assessment

of the valves, apart from coronary angiography,

provided the quality of the examination is

adequate This requires a combination of skill,

good equipment and a suitable patient In a

few patients with chest deformity or very bulky

lungs the echo data may be incomplete

Trans-oesophageal placement of the echo probe

permits the acquisition of high-quality images

in all patients The procedure is well tolerated

and quick so it has found increasing application

from out-patient to intraoperative recording

Pericardial effusions are easily identified by

echocardiography even when they are very

small, but pericardial thickening is usually

invisible and pericardial constriction is

ident-ified only indirectly by this means

Computed transaxial tomographic (CT)

scan-ning has relatively few indications in heart

disease but is very useful in the recognition of

pericardial disease, aneurysm and dissection

Left ventricular thrombus can usually be

detected by echocardiography but also shows

well on CT scans CT scanning provides one

of the best means of visualising the pericardium,

its thickness and the presence of an effusion

Fig 2.1

It is also a good means of demonstrating aortic dissection The flap is well shown and the whole length of the aorta can be displayed Digital subtraction angiography (DSA) pro-vides a relatively non-invasive means of display-ing the vascular tree after intravenous contrast injection but often needs to be supplemented

by central aortic or selective injections if a critical area of interest in a carotid or renal artery is not clearly seen DSA is unsatisfactory for showing details of coronary artery disease because of superimposition of the arteries upon themselves and on the left ventricle, but coronary bypass grafts can be shown by DSA although without detail

The potential of nuclear magnetic resonance imaging (NMRI) has yet to be fully realised and is advancing rapidly It can be used as an extravagant imaging technique but much more excitingly for measurement of blood flow However, NMRI is available only to a few, and, although with the help of sophisticated computers details of coronary artery anatomy and wall structure can now be shown, it will

be some years before NMRI has more general application in cardiology

Invasive Investigation

It is generally agreed that coronary angiography should be carried out before aortic or mitral

valve replacement in all patients with angina

or risk factors for coronary disease and in men

aged over 40 years and women over 50 years

irrespective of symptoms or risk factors When

reoperation is contemplated, it is usually

unnecessary to repeat coronary angiography if

the coronary arteries were strictly normal on

angiography within the last 5 years but it should

be repeated if there was even slight evidence

of atheromatous irregularity As coronary

angi-ography is nowadays the major reason for

carrying out cardiac catheterisation in valve

patients, it is the need for coronary angiography

which dictates the need for the investigation

and not the other way around, as used to be

the case when left and right heart

catheteris-ation was carried out for assessment of the

valves and coronary angiography was added

for good measure

Reasons for Failure of Previous

Operations

Wrong Indication or Wrong Operation

It is important to establish whether the

oper-ation was initially fully or partially successful

or whether it was a failure from the beginning

This may be difficult because of the honeymoon

period when patients may successfully persuade

themselves that all is well If an operation was

a failure from the beginning it may have been

because of a serious complication such as major

perioperative myocardial infarction,

parapros-thetic leak or severe mechanical haemolysis,

but it may have been because the indications

or the operation were wrong (Westaby 1985)

Mitral stenosis may not have been relieved

because the valve was unsuitable for valvotomy

and should have been replaced A mitral valve

repair may never have worked, and the surgeon

should have carried out intraoperative

assess-ment of valve competency and replaced the

valve Young patients with high expectations

may complain of severe physical disability with

relatively mild mitral valve disease and then

be outraged by the limitations imposed by even

a well-working prosthesis The converse is true

of older people with very chronic disease who

may not complain until all energy-conserving

devices to increase their efficiency have come

to an end and they have practically ground to

a halt Such patients are usually high operative risks and may not do well postoperatively Preoperative investigation in valve disease is designed to identify the severity of malfunction

of valves which are not at present causing symptoms but may do so in the near future

In the same way it is important to identify

coron~ry disease in a patient with severe mitral valve disease who is complaining only of shortness of breath but postoperatively may complain only of angina Equally, patients may have extracardiac causes of disability and the association of bronchial asthma with mitral stenosis may lead to either the mitral stenosis

or the asthma being underestimated and the wrong system blamed and treated

A poor result may follow a bad decision to conserve a valve which should have been replaced, or the choice of the wrong style or size of prosthesis Placement of an oversized mitral Starr valve in the small or normal sized ventricle of the patient with mitral stenosis can lead to the development of outflow gradients (Jett et al 1986) or recurrent ventricular arrhythmias, particularly if the cage of the Starr valve points across the left ventricular outflow tract onto the septum rather than down towards the apex

Valve Disease

After Mitral Valvotomy/Repair

Although a mitral valvotomy or reconstructive procedure may have been ill-judged and a failure from the outset, the need for reoperation

at some time in the future is likely in most patients for whom an excellent mitral valvo-tomy or repair was initially performed Reope-ration-free survival in one large series was 70%, 42% and 15% at 10, 20 and 28 years, respectively (Nakano et al 1986) The more nearly normal the function of the mitral valve after valvotomy or repair, the longer the operation will last (Nakano et al 1986; Gautam

et al 1986) Closed mitral valvotomies carried out "prophylactically" in young women about

to become pregnant 20 or 30 years ago have lasted even up to the present time without the