Ebook Herzog''s CCU: Part 2

for the management of acute coronary syndrome, echocardiography in acute coronary syndrome, use of radionuclide imaging in acute coronary syndrome, computed tomographic angiography in acute cardiac care

INTRODUCTION

Acute aortic syndrome (AAS) represents a spectrum of life-threateningconditions with similar clinical presentation and the need for urgentmanagement It includes classic acute aortic dissection (CAAD), intramuralhematoma (IMH), and penetrating aortic ulcer (PAU) Although not included inthe original definition of AAS, traumatic aortic rupture (TAR) and aorticaneurysm rupture have also been considered to be part of the AAS spectrum.AAS is characterized by disruption of the media layer of the aorta andtypically presents with acute chest pain The term “acute aortic syndrome” wasfirst coined in 2001 by the Spanish cardiologists Vilacosta and San Román, whodescribed AAS as a spectrum of interlinked lesions1 with the intent to increase

awareness and to speed up diagnosis and appropriate treatment (Figure 32.1).

Román Arrows signify possible progression of aortic lesions (penetrating aortic ulcer to IMH, penetrating aortic ulcer to classic dissection, IMH to classic dissection) IMH, intramural hematoma.

Although the incidence of AAS is lower than that of acute coronary syndrome(ACS), AAS carries a higher mortality, and is therefore a critical component ofthe differential diagnosis of chest pain in the Cardiac Care Unit (CCU) Overallincidence of AASs is 2 to 4 cases per 100,000 individuals Because AAS is rare,the International Registry of Acute Aortic Dissection (IRAD) was created in

1996 as a way to combine data acquired from multiple top institutions in Europe,North America, and Asia.2 The 2010 intersocietal guidelines for the diagnosisand management of patients with thoracic aortic disease proposed a standardapproach to the diagnosis and treatment of AAS.3

Although clinical history and physical examination are important, imaging isessential in the diagnosis of AAS Transesophageal echocardiography (TEE),computed tomography (CT), and magnetic resonance imaging (MRI) are thepreferred imaging modalities and angiography is rarely needed

CLASSIFICATION OF ACUTE AORTIC SYNDROMES

Historically, CAAD was the first recognized form of AAS The classificationschemes used for the classic aortic dissection were subsequently extended to

AASs are classified on the basis of the location and extent of involvement ofthe aorta Two systems have been proposed, the DeBakey and the Stanford

systems (Figure 32.2) The DeBakey system, which was proposed in 1965 by

the Lebanese-American surgeon Michael Ellis DeBakey, divided aorticdissection into three types based on the anatomic location Type I originates inthe ascending aorta and propagates beyond the aortic arch, type II is limited tothe ascending aorta only, and type III is limited to the descending aorta.4

FIGURE 32.2 DeBakey and Stanford classifications Left: DeBakey classification of aortic dissection.

Type I includes the ascending and descending aorta, type II includes the ascending aorta only, and type III includes the descending thoracic aorta only (DeBakey ME, Henly WS, Cooley DA, et al Surgical

management of dissecting aneurysms of the aorta J Thorac Cardiovasc Surg 1965;49:130-149.) Right:

Stanford classification Type A aortic dissection involves the ascending thoracic aorta, and type B involves the descending thoracic aorta only All three AAS conditions; CAAD, IMH, and PAU use the Stanford classification CAAD, classic acute aortic dissection; IMH, intramural hematoma; PAU, penetrating aortic

ulcer (Daily PO, Trueblood HW, Stinson EB, et al Management of acute aortic dissections Ann Thorac

Surg 1970;10[3]:237-247.)

The Stanford system, which was created by researchers at Stanford University

in 1970, divides aortic dissections into two types Type A includes any dissectionthat involves the ascending aorta, whereas type B dissections are limited to thedescending thoracic aorta.5 The Stanford classification appears to have wideracceptance and is now used for all three AAS types: CAAD, IMH, and PAU

INTRAMURAL HEMATOMA

IMH is defined by crescentic or circumferential thickening of the media layer of

the aortic wall IMH is likely due to a ruptured vasa vasorum resulting inintramural bleeding but without a detectable intimal tear It was first described in

1920 by the German pathologist Ernst Kruckenberg, who is also well known forhis description of the so-called Kruckenberg tumors (transperitoneal ovarianmetastases from stomach and colon cancers) On TEE, CT, or MRI, IMH istypically visualized as a crescentic or concentric thickening of the aortic wall > 5

mm (Figure 32.3) The natural history of IMH often includes progression to

CAAD, which accounts for its high morbidity and mortality

FIGURE 32.3 Intramural hematoma: CT CT of the chest shows the descending thoracic aorta The

crescentic-shaped lesion on the patient’s left signifies an IMH (dashed arrows) CT, computed tomography; IMH, intramural hematoma.

Etiology and Pathophysiology

IMH may account for up to 6% to 30% of all AAS, with a higher reportedprevalence among the Korean and Japanese populations as compared withWestern subjects.6 It is unclear whether this is a true discrepancy in prevalenceversus a reflection of differing classification, evaluation, or treatment practices.Often, IMH is diagnosed as such even though very small intimal tears indicative

of limited aortic dissection may be present but missed by modern imagingmodalities This may overestimate the true prevalence of IMH as opposed toCAAD

The characteristic feature of IMH is its location in the portion of the mediacloser to the adventitia, as opposed to CAAD which is typically located in themedia closer to the intima Although the most cited hypothesis of thepathophysiologic mechanism of IMH is rupture of the vasa vasorum, there isvery little corroborating clinical or experimental evidence Owing to the lowincidence of IMH and the close association with CAAD, a definitive etiologystill remains unclear.7

Clinical Manifestations

According to the IRAD experience, IMH typically presents with the symptoms

of severe chest and back pain, similar to CAAD However, IMH is less likely topresent with manifestations of severe aortic regurgitation and pulse deficits.6IMH is rarely stable It may either progress to CAAD or regress spontaneously,and therefore serial imaging is crucial Stanford type B lesions in the descendingaorta are more common than type A lesions in the ascending aorta (60% vs 35%

of all IMH, respectively) Cardiogenic shock may be present in 14% of patients,more typically with type A IMH.8 Pericardial effusion and tamponade may also

be present, which are also more common in type A IMH When compared withCAAD, type A IMH has a significantly higher risk of rupture (26% vs 8%,respectively).9 A widened mediastinum may be present on chest X-ray; however,this is neither sensitive nor specific to IMH

Diagnosis

As with all types of AAS, rapid diagnosis is paramount in IMH TEE, CT, andMRI are the preferred diagnostic tools CT is often chosen because ofwidespread availability, rapid acquisition, and its ability to diagnose other causes

of acute chest pain such as trauma and pulmonary embolism

Classically, absence of an intimal flap or tear differentiates IMH from CAAD.Often, IMH can be identified even on non–contrast-enhanced CT On contrast

CT scans, a crescentic or circular area of high attenuation that does not enhancewith contrast is present Similar findings are seen on MRI, which has theadvantage of not requiring iodinated contrast

Small intimal tears may be missed by any modern imaging technique,challenging the diagnosis of classic IMH

Management and Prognosis

The prognosis of IMH is somewhat better than that of CAAD As in all AAS, themain determinant of prognosis is its aortic location According to the IRADregistry, the mortality of type A IMH is approximately 27%, compared with 4%

in type B IMH Invasively managed patients with type A IMH typically farebetter than medically managed patients Invasive options include open surgicalrepair and percutaneous thoracic endovascular aortic repair Medicalmanagement typically consists of heart rate (HR), blood pressure, and paincontrol Surgical mortality for IMH is similar to that for other forms of AAS.Type B IMH is often managed medically Approximately 50% of type Bpatients may improve with medical management alone, 15% will remain stable,and 35% may progress to aneurysm formation, CAAD, or focal aortic rupture(pseudoaneurysm).10

Intramural Hematoma in Pregnancy

Although there are no specific guidelines in pregnancy for patients with IMH,pregnancy is considered a risk factor for the development of aortic pathology,especially in Marfan syndrome As with other forms of AAS, expedited deliveryvia caesarian section is considered reasonable for pregnant patients with acuteIMH, if possible

CLASSIC ACUTE AORTIC DISSECTION

CAAD is the most common form of AAS.2 It occurs in approximately 66% to75% of all AAS The overall incidence of CAAD is low, estimated at 0.5 to 4.0cases per 100,000 per year, and is thought to affect men more than women in a2:1 ratio

Risk factors for CAAD include connective tissue disorders such as Marfan

(fibrillin gene), Loeys–Dietz (transforming growth factor β receptor 1 and 2

genes), Ehlers–Danlos type 4 (collagen gene), and Turner syndrome (Xmonosomy), as well as the aortopathy associated with bicuspid aortic valve

very famous description of CAAD was by the British royal physician FrankNichols (1699–1778) who provided the first unmistakable account of CAAD(deemed a “Transverse fissure of the aortic trunk”) in his autopsy of KingGeorge II, who died in 1760 while straining in the lavatory Successful surgicalrepair of descending aortic dissection was not reported until 1955, by MichaelDebakey (1908–2008) and his colleagues, and ascending dissection until 1962

by Frank Spencer and Hu Blake.13,14

Etiology and Pathophysiology

CAAD is characterized by an intimal tear, which leads to abnormal blood flow

from the aortic lumen into the media (Figure 32.5) Consequently, there is a

longitudinal separation of the media layers by the blood flow, which tears an

intimomedial flap from the remainder of the aortic wall (Figure 32.6A–C) This

flap separates the abnormal false lumen from the true aortic lumen Intimal tearstypically occur at the locations within the aorta with the highest shear stress.These are at the right side of the ascending aorta immediately distal to the ostium

of the right coronary artery (type A dissections) and immediately distal to theostium of the subclavian artery adjacent to the insertion of the ligamentumarteriosus (type B dissections)

Doppler of the aortic arch in the upper esophageal view Yellow arrow points to the entry point of flow from the true lumen to the false lumen, characteristic of CAAD CAAD, classic acute aortic dissection; FL, false lumen; TEE, transesophageal echocardiography; TL, true lumen.

FIGURE 32.6 Classic acute aortic dissection: CT Multidetector row CT with intravenous iodinated

contrast in the axial view (A), sagittal view (B), and the coronal view (C) Yellow arrows point to dissection flap at the junction of the aortic arch and descending thoracic aorta, consistent with CAAD CAAD, classic acute aortic dissection; CT, computed tomography.

Complications such as aortic regurgitation and pericardial tamponade canoccur; and, over time, chronic changes such as false lumen thrombosis andaneurysm are common

Clinical Manifestations

The typical symptom of acute aortic dissection is “aortic pain” similar to otherforms of AAS Acute, severe, tearing chest pain is the hallmark symptom ofCAAD Pain limited to the chest is typical of type A CAAD, and pain in the back

is more often the symptom of type B CAAD One study found older patients areless likely to abrupt onset of pain as compared with younger patients.15

Pulse deficit, present in up to 33% of patients according to the IRAD study,reflects impaired or absent blood flow to peripheral vessels This is manifested

by weak carotid, brachial, or femoral pulses on physical examination

Other physical examination findings of CAAD include diastolic murmur oraortic regurgitation, hypotension related to either tamponade or aortic rupture,focal neurologic deficits reflecting propagation of the dissection towardinvolvement of carotid or cerebral arteries, and syncope

Electrocardiogram (ECG) may be useful in distinguishing the chest pain ofAAS from ACSs; unlike ACS, uncomplicated CAAD does not present withischemic ECG changes However, if the aortic dissection leads to coronaryischemia through involvement of coronary ostia (type A), the ECG will be lesshelpful with differentiation of symptoms

Chest X-ray (CXR) imaging occasionally shows widening of themediastinum, a nonspecific finding seen with other syndromes such asmediastinal hematoma Other CXR findings are double aortic knob (40% ofpatients), tracheal displacement to the right, and enlargement of the cardiacsilhouette

Serum biomarkers such as D-dimer are often elevated in CAAD, but this is anonspecific finding In contrast, a normal D-dimer level may help exclude thediagnosis of CAAD Investigational biomarkers such as elastin degradationproducts, calponin, fibrinogen, fibrillin, and smooth muscle myosin heavy chainare currently being evaluated

Diagnosis

As with other forms of AAS, the 2010 intersocietal guidelines for the diagnosisand management of patients with thoracic aortic disease provide a usefuldecision tool to help guide diagnostic and management strategies for CAADwith a special emphasis on a combination of clinical risk assessment and rapidimaging

CT with intravenous iodinated contrast is often the diagnostic modality ofchoice for CAAD because of its superb spatial resolution, rapid acquisitiontimes, widespread availability, and its ability to diagnose other causes of acute

CT for CAAD is 87% to 94% and specificity is 92% to 100% CT features ofCAAD are intimal tear, dissection flap with a true and false lumen, dilatation ofthe aorta, and pericardial effusion

TEE is especially useful in the diagnosis of CAAD when a CT with contrastcannot be performed, such as in hemodynamically unstable patients or inpatients in whom the risk of iodinated intravenous contrast is high such as renalinsufficiency or severe allergy The reported sensitivity of TEE is 98% andspecificity is 63% to 93% Findings on TEE are a dissection flap separating thetrue and false lumen, site of intimal tear represented by flow from the true lumen

into the false lumen on color Doppler (Figure 32.7) Spectral Doppler may help

corroborate the diagnosis by demonstrating “to and fro” flow into and out of thefalse lumen

FIGURE 32.7 Classic acute aortic dissection: dissection flap on TEE Two-dimensional (2D) TEE of the

ascending thoracic aorta in short axis (A) and long axis (B) demonstrating CAAD In this case, the dissection flap is circumferential with a 360° separation of the true and false lumens CAAD, classic acute aortic dissection; FL, false lumen; TEE, transesophageal echocardiography; TL, true lumen.

The true lumen is identified by its expansion with systole and contraction indiastole The true lumen is often smaller than the false lumen In early stages, thefalse lumen may be echo free or may contain spontaneous echo contrast (alsoknown as “smoke”) due to stasis of blood flow In later, more chronic stages, thefalse lumen may be partly or completely obliterated by thrombus formation.Complications of CAAD may be seen on echocardiography such as aorticregurgitation, pericardial effusion/tamponade, and wall motion abnormalitiesindicative of ischemia if there is coronary ostial involvement

It is important not to confuse the intimomedial flap of CAAD with eitherartifacts or surrounding vascular structures Linear reverberation artifacts in theascending aorta should not be mistaken for type A aortic dissection Typically,reverberation artifacts are located twice as deep as the anterior aortic wall Inaddition, a dilated azygos vein adjacent to the descending thoracic aorta maygive an illusion of a type B dissection Color or spectral Doppler imaging in bothinstances may help distinguish true aortic dissection from its masqueraders

(Figure 32.8).

FIGURE 32.8 Reverberation artifact masquerading as type A dissection on TEE Two-dimensional (2D)

TEE of the ascending thoracic aorta in a long-axis view (A) and a short-axis view (B) Red arrows point to linear reverberation artifact Note that the reverberation artifact is located twice as deep (2×) as the anterior aortic wall, characteristic of reverberation artifacts TEE, transesophageal echocardiography.

Although on transthoracic echocardiography (TTE) aortic dissection canoccasionally be seen, TTE should only be used as a screening tool owing to lack

of sufficient sensitivity and specificity

MRI and aortography also may reveal aortic dissection; however, they arereserved for specific situations MRI may be used when the patient cannotreceive iodinated contrast for CT nor undergo TEE Aortography is of limiteduse and is typically performed during invasive endovascular therapeuticprocedures

Management and Prognosis

Type A CAAD is a true medical emergency, requiring immediate surgical repair

because the mortality increases by the hour Approximately 90% of medicallymanaged patients with type A CAAD die within 3 months of presentation Onthe other hand, the prognosis is more favorable for patients with type B CAAD

in whom medical management is often preferred over surgical repair becausesurgically managed patients have been shown to have higher mortality comparedwith those on medical therapy alone Medical therapy generally consists of tight

blood pressure control and β-blockade Surgical management of type A CAAD

typically consists of excision of the intimal tear if possible and obliteration ofentry into the false lumen, as well as implantation of a graft to replace theascending aorta.16 Surgical therapy for type B is more complicated because ofthe presence of many spinal artery branches, and therefore has a risk ofparaplegia Nevertheless, surgical therapy of type B dissection is often necessarywhen there is aortic branch ischemia and end-organ damage Endovascular graft

therapy to treat type B CAAD has shown promise (Figure 32.9).17

FIGURE 32.9 Endovascular graft repair: 3D CT Three-dimensional (3D) reconstruction of

contrast-enhanced chest CT in a sagittal view (A) and coronal view with surrounding structures removed (B) demonstrating an endovascular stent graft located between the junction of the aortic arch and descending thoracic aorta, extending to the distal descending thoracic aorta CT, computed tomography.

It is important to identify risk factors for higher mortality in type A CAADsuch as advanced age, prior cardiac surgery, hypotension or shock, pulse deficit,cardiac tamponade, and ischemic ECG changes

The 2010 intersocietal guidelines for the diagnosis and management of patientswith thoracic aortic disease recommends expedited fetal delivery via caesariansection for patients with CAAD during pregnancy given the high mortality of thedisease (class IIa recommendation) The diagnostic imaging modality of choice

is MRI without gadolinium to avoid exposing the mother and fetus to ionizingradiation.18 TEE is an option and is considered safe in pregnancy; however,caution must be used when providing procedural sedation because themedications typically administered (midazolam and fentanyl) may beteratogenic, especially in the first trimester In these cases, topical anesthesiawith viscous lidocaine is crucial There have been reports recommendingmonitoring fetal HR and uterine tone during TEE.19

FIGURE 32.10 Penetrating aortic ulcer: TEE Two-dimensional (2D) TEE of the descending thoracic aorta

in the midesophageal short-axis view (A) and long-axis view (B) Yellow arrows point to demonstrating severe atherosclerotic plaque and PAU; yellow dashed arrows point to an area with developing IMH IMH, intramural hematoma; PAU, penetrating aortic ulcer; TEE, transesophageal echocardiography.

(A) and 3D CT (B) Arrows point to PAU with aortic rupture and pseudoaneurysm of anterior portion of the proximal descending thoracic aorta CT, computed tomography; PsA, pseudoaneurysm.

Etiology and Pathophysiology

PAU accounts for 2% to 11% of all AASs.20,21 It was first described in 1986 byAnthony Stanson and colleagues.22 Patients with PAU typically are older (>70years old) and have risk factors for atherosclerosis including hypertension,smoking, and hyperlipidemia

The natural history of PAU is not well described PAU may cause remodeling

of the aortic wall and aneurysm formation, contained rupture through the aorticwall and attendant pseudoaneurysm formation, complete aortic rupture withmediastinal or pleural hemorrhage, or progression to IMH and CAAD

Clinical Manifestations

Symptoms of PAU are similar to that of other AASs The pain associated withPAU is variable, and dependent on the location of the ulceration Type A PAUtypically presents with chest pain and type B PAU is more likely to present withback pain Unlike IMH or CAAD, there have been reports of PAU as anincidental finding in asymptomatic patients

Diagnosis

The diagnosis of PAU is primarily made by CT, TEE, and MRI Aortography is

not typically used for PAU because of lack of direct visualization of the aorticwall All three techniques are able to image atherosclerotic changes, ulceration,and complications such as pseudoaneurysm, rupture, and mediastinal and pleuralhemorrhage Identification of an ulcer crater distinguishes PAU from IMH PAUlesions are typically focal as opposed to those of CAAD and IMH, which aremore extensive.

Management and Prognosis

The natural history of PAU is poorly understood On one hand, PAU isconsidered to be a surgical emergency with risk similar to or worse than otherforms of AAS On the other, reports have described the progression of PAU asslow, with a low prevalence of life-threatening complications.23 There istherefore equipoise regarding the optimal medical versus surgical treatmentstrategies Nevertheless, surgical management of PAU with aortic grafting isconsidered appropriate in the presence of aortic rupture, persistent or recurrentpain, hemodynamic instability, or rapidly expanding aortic diameter

Etiology and Pathophysiology

The most common site of injury in TAR is at the aortic isthmus, immediatelydistal to the left subclavian artery at the site of the ductus arteriosus Thislocation is considered to be the most vulnerable to torsional and shear forcesbecause it is thought to be a transition zone between the semi-mobile aortic archand the fixed descending thoracic aorta Other possible sites of injury are thetransverse arch, ascending aorta, and descending aorta proximal to the

diaphragm.27 Typically, the intima and medial layers rupture first, followed byrupture of the adventitia after an unpredictable interval of time.28 Multiple tearsmay occur.

Diagnosis

TAR is best diagnosed using either contrast-enhanced CT or TEE because both

modalities have high diagnostic sensitivity and specificity (Figure 32.12).

Findings seen on CT include intimal flap, periaortic hematoma, luminal fillingdefects, pseudoaneurysm, or active extravasation of contrast from the aorta It isimportant to distinguish TAR from a ductus arteriosus diverticulum, which ishelped by the improved special and temporal resolution of modern multidetectorrow CT scanners However, TEE may be more specific in differentiating ductusarteriosus diverticula from TAR Another very useful advantage of TEE is itsportability, with the ability to be performed at the bedside of hemodynamicallyunstable patients, a common scenario in TAR The main limitation of TEE is anapparent “blind spot” at the distal ascending aorta and proximal aortic archcaused by bronchial shadowing Aortography, the former gold standard, may beperformed; however, it is invasive and can result in worsening of the aorticrupture in as many as 10% of patients and is therefore not the preferreddiagnostic modality

FIGURE 32.12 Traumatic aortic rupture CT of the chest with iodinated contrast, coronal view (A), and

TEE upper esophageal view (B) of the aortic arch Arrows point to traumatic aortic rupture Note that the TEE image was rotated to align with the CT image CT, computed tomography; TAR, traumatic aortic rupture; TEE, transesophageal echocardiography.

Management and Prognosis

Emergent surgical therapy is the standard of care for TAR As with AAS,medical therapy consists of very close blood pressure and HR control.Hemodynamically unstable patients should be operated on immediately Surgicaloptions comprise open repair with prosthetic grafts, and endovascularlydelivered fabric-covered stents Endovascular repair has been shown to havedecreased overall mortality compared with surgical repair and is recommendedwhen possible The overall survival of TAR is approximately 10% to 18%.Survival to emergency room care greatly improves the odds of long-termsurvival, and survival to surgical therapy improves the odds even more, toapproximately 70% to 90%.29

Traumatic Aortic Rupture in Pregnancy

Although there are no specific guidelines for the management of TAR inpregnancy, expedited delivery via caesarian section with emergent aortic surgery

is a reasonable therapeutic approach given the high mortality both to the motherand fetus

REFERENCES

14 Spencer FC, Blake H A report of the successful surgical treatment of aortic regurgitation from a

dissecting aortic aneurysm in a patient with the Marfan syndrome J Thorac Cardiovasc Surg.

1962;44:238-245.

15 Pape LA, Awais M, Woznicki EM, et al Presentation, diagnosis, and outcomes of acute aortic

dissection: 17-year trends from the International Registry of Acute Aortic Dissection J Am Coll

Once the diagnosis of AAS is established by CT, TEE, or MRI, the disease istypically treated with mediations that lower blood pressure and HR The doctorwill determine the type of AAS (type A or type B) based on the location ofinvolvement in the aorta A cardiothoracic surgeon may be consulted, who willassess the need for surgery Surgery is often needed as soon as possible

WHAT IF THE PATIENT IS PREGNANT OR THINKING OF

BECOMING PREGNANT?

Given the high mortality of AAS and the frequent need for emergency cardiacsurgery, the doctor may recommend expedited delivery If at risk of AASbecause of genetic conditions that may affect the aorta, the patient should consultthe doctor to assess the risk if she is thinking about becoming pregnant

INTRAMURAL HEMATOMA

IMH is described as bleeding into the wall of the aorta due to breakage of theinternal blood vessels of the aorta Symptoms of IMH are sudden severe chest orback pain IMH is best diagnosed by imaging the aorta using CT, TEE, or MRI

On experiencing symptoms suggestive of IMH, the patient or a family membershould seek medical care immediately because the risk of dying from thiscondition increases by the hour

HOW WILL THE PATIENT BE TREATED?

Once the diagnosis of IMH is established, medications will be given to reducethe blood pressure and HR A cardiothoracic surgeon may be consulted, who willassess the need for surgery Surgery will often involve either replacement of thediseased portions of the aorta or placement of special type of stent within theaorta that will help contain the bleeding and prevent the aorta from bursting

WHAT IF THE PATIENT IS PREGNANT OR THINKING OF

BECOMING PREGNANT?

IMH carries a high risk of mortality, and often requires emergency surgery Thedoctor will tailor the medications for IMH to include only those with minimalrisk to the baby If the pregnant patient or family member requires emergencysurgery, expedited delivery is prudent Rapid consultation with an obstetrician iscrucial If the person has a condition that puts her at risk for IMH such as Marfansyndrome or other genetic disorders of the aorta, consult the doctor to assess therisk if thinking about becoming pregnant

CAAD will be diagnosed using CT, TEE, or MRI, which are widely availableand can be performed and interpreted rapidly

HOW WILL THE PATIENT BE TREATED?

As with other types of AAS, the doctor will prescribe medications that lowerblood pressure and HR A cardiothoracic surgeon may be consulted immediately,who will assess the need for surgery The location of the dissection is a crucialcomponent in deciding what the best treatment is Surgical options are openheart surgery or placement of a tube called stent The cardiothoracic surgeon willassess which procedure is the most appropriate

PENATRATING AORTIC ULCER

WHAT IS THE ILLNESS?

Atherosclerosis or hardening of the arteries is a disease in which cholesterol andfat build up within the walls of the blood vessels called arteries PAU is causedwhen a very severe plaque breaks through the aorta, causing a hole, orulceration Risk factors for PAU include advanced age, high blood pressure, highcholesterol, and smoking Symptoms include chest and back pain, although somepatients may have no symptoms

HOW WILL THE PATIENT BE TREATED?

Emergency surgery is the standard of care for TAR The doctor may prescribemedications to lower HR and blood pressure if necessary; however, acardiothoracic surgeon may be consulted as soon as possible Treatmenttypically requires open heart surgery

WHAT IF THE PATIENT IS PREGNANT OR THINKING OF

BECOMING PREGNANT?

Because TAR is a surgical emergency, consultation with an obstetrician for earlydelivery is crucial

The surgeon may recommend delivery by cesarean section at the time ofsurgery to repair the broken aorta

INTRODUCTION

Pericardial effusion is a relatively common finding in high-risk patientsevaluated in the acute setting.1 It should be considered in differential diagnosisfor a variety of clinical presentations including chest pain, shortness of breath,and hypotension.1 Pericardial effusion can be directly causal for patients’complaints (like in patients with pericardial tamponade) or be an incidentalfinding still carrying a prognostic significance (like in patients with pulmonaryhypertension) The general approach to pericardial effusion once it is recognizedincludes establishing the cause of pericardial disease and assessing itshemodynamic significance

ESTABLISHING THE CAUSE OF PERICARDIAL EFFUSION

There is a long list of possible causes for pericardial effusion (Table 33.1), but a

limited number of etiologies account for the majority of diagnoses.5 A structuredapproach helps establish the cause of pericardial effusion in most cases.6 A veryaggressive approach, as is used in some studies, has a high diagnostic yield butlow clinical relevance, especially for small effusions.7,8 Routine sampling ofpericardial fluid for diagnostic purposes is unnecessary.3 History and physicalexamination often provide clues to the etiology of pericardial effusion Forexample, the pericardium can be involved in patients with active systemicmalignancy, and malignant effusion should be strongly considered in thesepatients Active or recent infection, radiation therapy, rheumatic disease, andrecent acute coronary syndrome, cardiac surgery, or percutaneous cardiacprocedure, all provide relevant clues to etiology A typical clinical presentation,physical findings, and electrocardiographic changes commonly confirm thediagnosis of acute idiopathic pericarditis.9 In one study, the presence of

“inflammatory” signs (characteristic chest pain, pericardial friction rub, fever,and/or diffuse ST-segment elevation) in patients with pericardial effusion wasstrongly associated with acute idiopathic pericarditis.10

in the right epidemiologic and clinical settings Viral cultures have little clinicalsignificance and should not be routinely obtained, but they may be useful insome patients (eg, cytomegalovirus infection in transplant patients).3Transesophageal echocardiography can diagnose loculated effusion whentransthoracic echocardiography is limited (eg, postoperative patients) andregional tamponade is considered Our structured approach has yielded diagnosis

by noninvasive targeted testing in 68% of patients, based on a retrospectivereview.6

FIGURE 33.2 Parsimonious stepwise approach to laboratory testing and imaging in patients with

pericardial effusion This systematic approach allows establishing diagnosis noninvasively in the majority

of patients with moderate-to-large pericardial effusion Question mark indicates optional and controversial.

Simple clinical assessment has also been shown to assist in establishing thediagnosis: large effusion without “inflammatory” signs or clinical signs oftamponade (jugular venous distension, hypotension, and/or pulsus paradoxus)commonly signifies chronic idiopathic pericardial effusion (likelihood ratio = 20,

ASSESSING HEMODYNAMIC SIGNIFICANCE OF

PERICARDIAL EFFUSION

When evaluating the hemodynamic impact of pericardial effusion one shouldtake into account the acuity of presentation Acute accumulation of fluid (within

minutes to hours) rapidly exceeds the pericardial stretch limit and commonlypresents as cardiogenic shock.12 This dramatic presentation is called acute orsurgical tamponade and it requires immediate intervention Chamber perforationduring a percutaneous procedure is a good example of acute tamponade Bluntchest trauma and ascending aortic dissection resulting in blood accumulationwithin the pericardium require prompt surgical intervention, and percutaneouspericardial effusion drainage is relatively contraindicated When pericardial fluidaccumulates slowly (within days to weeks), a large amount of fluid can bepresent without dramatic lowering of the cardiac output.12 This can lead tosubacute or medical tamponade, which requires careful assessment of bothclinical and imaging data to establish the need for pericardial effusiondrainage.13 The following discussion elaborates the assessment for subacute(medical) tamponade.

HISTORY AND PHYSICAL EXAMINATION

Although many refer to pericardial tamponade as a “clinical diagnosis,” theexisting evidence suggests that subacute tamponade is a difficult diagnosis tomake on mere clinical grounds.13 Dyspnea is the cardinal symptom of subacutepericardial tamponade, but it is nonspecific Other symptoms such as fever,cough, and chest pain can occur and typically reflect the underlying cause (ie,pericarditis) rather than pericardial fluid accumulation Clinical findings ofpericardial tamponade include tachycardia, jugular venous distension, pulsusparadoxus, and diminished heart sounds; and all lack both sensitivity andspecificity.14 Tachycardia is common in hospitalized patients for many reasonsand it could be blunted by medications such as β-blockers In a systematicreview, the jugular venous distension had a pooled sensitivity of 76% forpericardial tamponade.14 Assessment of jugular venous distension is limited bythe experience of the observer; it can be difficult in some patients, even forexperienced clinicians Besides, jugular venous distension is associated withother conditions causing shortness of breath such as pulmonary hypertension andcongestive heart failure Although patients with acute (surgical) tamponaderapidly progress to cardiogenic shock, hypotension is rather uncommon inpatients with subacute tamponade who accumulate pericardial effusion withindays to weeks On the contrary, many patients are hypertensive because of thehigh levels of circulating catecholamines in response to hemodynamic stress In

127 to 144 mm Hg.15 According to a recent review, hypertensive tamponade isseen in 27% to 43% of patients.15 Systolic blood pressure commonly decreases

in these patients after pericardial effusion drainage, and treating the hypertensiveresponse without draining the effusion can be dangerous

PULSUS PARADOXUS

Pulsus paradoxus is considered the cornerstone of the clinical diagnosis ofpericardial tamponade.12 Under normal conditions, the decrease in bloodpressure is <10 mm Hg, and it is explained by phasic variation in the filling ofthe right- and left-sided cardiac chambers related to intrathoracic pressurechanges with respiration With tamponade, the accumulating pericardial effusionrestricts cardiac filling and makes the respiratory variation in the right and leftventricular filling more pronounced and interdependent.12 Pulsus paradoxus ismeasured by manual sphygmomanometer as the difference between intermittentand persistent Korotkoff sounds during normal respiration, not with deep

breathing (Figure 33.3).14 A wide variation in the incidence of pulsus paradoxushas been reported in patients with pericardial tamponade, ranging from 12% to75%.16 In patients with “low-pressure” tamponade, the incidence of pulsusparadoxus was reported as only 7%.17 Besides limited sensitivity for pericardialtamponade, pulsus paradoxus is not very specific A myriad of conditions havebeen reported to be associated with pulsus paradoxus; a short list includesasthma, right ventricular infarction, severe hypovolemia, constrictivepericarditis, restrictive cardiomyopathy, pneumothorax, chronic obstructive lungdisease, and pulmonary embolism.13 Some of these conditions can also causejugular venous distension and tachycardia, common associated findings ofpericardial tamponade

FIGURE 33.3 Assessing for pulsus paradoxus Pulsus paradoxus is measured by manual

sphygmomanometer as the difference between intermittent and persistent Korotkoff sounds during normal respiration.

INVASIVE AND IMAGING DATA

Before the widespread use of echocardiography, invasive data using cardiac

catheterization were commonly obtained to confirm the diagnosis of tamponade.Cardiac catheterization in tamponade demonstrates equilibration of diastolicintracardiac pressures and respiratory variation in right- and left-sided cardiacpressures corresponding to pulsus paradoxus.

Echocardiography is currently the cornerstone of hemodynamic evaluation ofpericardial effusion.4 Pericardial effusion is easily recognized during ultrasound

examination as an echo-free space around the heart (Figure 33.4) Normally,

intrapericardial pressure is lower than the central venous pressure As pericardialfluid accumulates, the intrapericardial pressure equilibrates first with the right-sided filling pressures and then left-sided filling pressures.14 During tamponade,intrapericardial pressure temporarily exceeds intracavitary pressure in various

chambers during the cardiac cycle and results in chamber collapse (Figure

33.5).4 Certain pitfalls should be kept in mind when interpretingechocardiographic findings Transient buckling of the right atrium is commonlyseen in patients with pericardial effusion and it is not specific A more sustainedcollapse of the right atrium lasting at least one-third of the cardiac cycle appears

to be more specific for pericardial tamponade.18 Right ventricular early diastoliccollapse is a less sensitive finding but has a high specificity Left-sided chambercollapse is much less sensitive but highly specific for tamponade Importantly, astudy by Merce et al showed that 34% of patients with pericardial effusion butwithout clinical features of pericardial tamponade had at least one chambercollapse on echocardiography.19 Therefore, in patients with pericardial effusionwho have chamber collapse, one should carefully document respiratory flow

variation across valves as a sign of ventricular interdependence (Figure 33.6)

and interrogate the inferior vena cava size and collapsibility as a sign of elevatedright-sided filling pressures.20 The presence of respiratory variation in the inflowvelocities is defined by consensus as >30% across the mitral valve and >60% forthe tricuspid valve.4 These echocardiographic signs, when present, increase thespecificity of diagnosis Finally, the size of the pericardial effusion seems to be

an important but frequently underappreciated part of the echocardiographicassessment In one study of hospitalized patients with pericardial effusion, thesize of the effusion was the only independent predictor of adverse in-hospitaloutcomes in a multivariate model, but not chamber collapse or inferior vena cavaplethora.21

FIGURE 33.4 Pericardial effusion as seen with the ultrasound examination Pericardial effusion (Pef) is

easily recognized during ultrasound examination as an echo-free space around the heart.

FIGURE 33.5 Chamber collapse with pericardial tamponade as seen with the ultrasound examination.

There is evidence of right atrial collapse (arrowhead) as well as right ventricular compression by pericardial fluid (arrow).

FIGURE 33.6 Doppler echocardiography in pericardial tamponade Respiratory variation in the mitral

inflow velocities (arrow) is seen.

The diagnosis of pericardial tamponade may be particularly difficult inpatients with pulmonary hypertension and right ventricular failure because theycommonly accumulate pericardial effusion Pericardial effusion in these patients

is a marker of adverse outcomes Common clinical findings of pericardialtamponade such as tachycardia and jugular venous distension may not be helpful

in differential diagnosis for shortness of breath and progressive right-sided heartfailure Collapse of the left-sided cardiac chambers has been described as animportant echocardiographic clue to the presence of pericardial tamponade inthese settings.22 Conversely, more common findings of tamponade such as rightatrial and ventricular collapse can be masked by elevated right-sided fillingpressures Poor outcomes have been reported with routine draining of pericardialeffusion in these patients

INTEGRATIVE APPROACH TO PERICARDIAL DRAINAGE