Advanced therapy in thoracic surgery - part 5 pdf

Simple Tracheal Resection This section describes our technique for uncomplicated resections of the middle and upper trachea.. Postoperative radiation therapy is recommended in all cases

steriods Tracheostomies may be useful in some patients

as the only way to secure an airway When possible, they

should be placed through the stenosis, preserving the

uninvolved trachea for future reconstruction

Anesthesia

An experienced anesthesiology team working in close

cooperation with the surgical team is essential

Replacement of spontaneous breathing with positive

pressure ventilation can convert a partially obstructing

lesion into a complete obstruction When maintenance of

the airway is a concern, a breathe down with an

inhala-tion agent is employed and paralytics given once the

airway is secured.20Anesthesia is maintained with total

intravenous anesthesia (TIVA) using short-acting agents

such as remifentanil and propofol This allows immediate

extubation at the completion of the procedure and

main-tains continuous anesthesia during periods when

inhala-tional agents are interrupted by the procedure When a

thoracotomy incision is used, epidural anesthesia

signifi-cantly decreases thoracotomy pain For lower tracheal

and carinal resections, endotracheal intubation is

accom-plished with an extra-long, armored endotracheal tube

Its flexibility allows bronchoscopic placement into one of

the main stem bronchi After transecting the airway, the

orotracheal tube is pulled back into the trachea and

intermittent ventilation is performed with sterile

cross-field equipment The orotracheal tube is again advanced

once the anastomosis is completed The anesthesiology

team should be familiar with the techniques of

high-frequency “jet” ventilation Cardiopulmonary bypass is

not helpful and only introduces unnecessary risks

Simple Tracheal Resection

This section describes our technique for uncomplicated

resections of the middle and upper trachea Rigid

bron-choscopy with dilation is performed at the time of

planned resection, and if the lesion appears amenable to

surgery, the patient is intubated, positioned, and

pre-pared for incision

For most relatively short lesions, the patient is placed

supine with an inflatable airbag beneath the shoulders

with the neck extended The inflatable bag is important

in alleviating tension since it can be deflated to facilitate

neck flexion just prior to tying down the anastomosis

The head and neck are supported in a foam “doughnut.”

The arms are tucked at the sides and only the neck and

upper sternum are prepared and draped

A low collar incision is adequate for most tracheal

resections involving the upper trachea Occasionally,

vertical extension with a partial sternal split is required

for middle to lower tracheal lesions (Figure 17-8A)

Dissection is carried through the platysma, and platysmal flaps are elevated superiorly to the level of thecricoid and inferiorly to the level of the sternal notch.The strap muscles are separated in the midline, and aplane of dissection is established very close to thetracheal wall to avoid injury to the recurrent laryngealnerves (Figure 17-8B) The pretracheal plane is dissected

sub-to the level of the carina The investing fascia of theinnominate artery and the adjacent mediastinal fat is leftintact to guard against postoperative tracheoinnominatefistulization The location and extent of the lesion maysometimes be identified by observation of changes in thetracheal wall as seen in the operative field Often,however, these changes are subtle, and the limits of theresection must be delineated by the surgeon transillumi-nating the trachea above and below the lesion with a flex-ible bronchoscope while the assistant watches the fieldand marks the limits of the lesion with fine sutures.The trachea is sharply dissected circumferentially atthe most distal extent of the lesion, with the dissectionplane maintained on the tracheal wall Sterile ventilatingtubing is then positioned under the ether screen andfastened to the drapes The endotracheal tube is with-drawn into the upper trachea, the trachea divided at themost distal extent of the lesion, and bilateral 2-0 Vicryltraction sutures placed such that they are anchoredaround a tracheal ring about 1 cm below the distal tran-section site A cuffed, armored Tovell tube is promptlypassed into the distal tracheal segment and attached tothe sterile connecting tubing, and crosstable ventilationcommenced (Figure 17-8C) The diseased segment oftrachea is sharply dissected from the esophagus and tran-sected at the most proximal extent of the lesion andpassed out of the field

The patient’s neck is then flexed and the anastomosistested for tension Using the traction sutures, the proxi-mal and distal segments can be brought towards oneanother When they come together without tension, theanastomosis can be created If the limits of flexion andsafe dissection have been reached and anastomotictension still exists, then one proceeds with release proce-dures (see below) It is simplest to anticipate the need forrelease procedures and perform them prior to dividingthe trachea, but this is not always possible

When the surgeon is satisfied that the anastomosiswill not be under tension, interrupted 4-0 Vicryl anasto-motic sutures are placed (but not tied) such that theknots will be on the outside, beginning posteriorly in themidline and proceeding around either side to the front(Figure 17-8D) The sutures are placed 5 to 6 mm fromthe cut edge of the trachea and 4 mm apart They shouldencircle a tracheal ring on either side of the anastomosis

to help prevent dehiscence Frequently, the Tovell tube

220 / Advanced Therapy in Thoracic Surgery

strap muscles In situations where postoperative

intuba-tion is thought to be necessary, a small uncuffed

endotra-cheal tube is left in place initially and a stitch placed on

the trachea to mark the site for tracheostomy should it

become necessary This allows limited dissection and

accurate placement in a reoperative field It is best to wait

a few days before placing a tracheostomy to allow skin

flaps and other tissue layers to seal before exposing them

to airway secretions This also allows for postsurgical

airway edema to resolve before committing to a

tracheostomy tube

For tumors, the approach is modified in a number of

ways Considerable experience is required to make the

judgment of whether a tumor can be safely resected with

sufficient tissue to provide a clear margin and yet allow

successful primary reconstruction of the airway This can

be particularly difficult in patients with adenoid cystic

carcinoma in whom frozen sections may show

micro-scopic tumor at grossly clear resection margins When

extension of resection to the more distal trachea is

required, an upper sternal split may be extended into the

right fourth interspace The plane of dissection in tumor

cases must be kept away from the involved portion of

trachea in order to ensure an adequate radial margin

This endangers the recurrent laryngeal nerves more than

in resections for benign disease If a recurrent nerve is

involved by tumor, the nerve is sacrificed Paratracheal

lymph nodes are removed en bloc with the specimen

when possible, but extensive lymph node dissection

cannot be done for fear of destroying the blood supply to

the remaining trachea Postoperative radiation therapy is

recommended in all cases of bronchogenic or adenoid

cystic carcinoma, unless contraindicated by performance

status or anastomotic complications.11

Laryngotracheal Resection

In cases where an upper tracheal lesion involves the

cricoid, occuring most commonly in idiopathic

laryngo-tracheal stenosis or tumor, a laryngolaryngo-tracheal resection

will be necessary In idiopathic laryngotracheal stenosis

the lesion typically involves the cricoid on its anterior

and lateral luminal surface The operative procedure

must be tailored to address the particular anatomical

involvement encountered (Figure 17-9) The recurrent

laryngeal nerves are protected by bevelling off the cricoid

anteriorly and laterally while preserving the posterior

plate.21,22 The extent of anterior cricoid resection ranges

from complete, with a line of transection through the

cricothyroid membrane to none at all, depending on the

extent of involvement Tracheal resection depends on the

distal extent of lesion (Figure 17-10A and B) The trachea

is appropriately tailored so that the proximal trachea

coapts well with the cut edge of the lar ynx (Figure 17-10C and D) 2-0 Vicryl “traction sutures” areplaced in the midlateral position both proximally anddistally Interrupted 4-0 Vicryl sutures were used to fash-ion the anastomosis The midline of the thyroid cartilage

is approximated to the midline of tracheal “prow.” 2-0Vicryl traction sutures are tied followed by individual 4-0Vicryl anastomotic sutures (Figure 17-10E and F)

This operation is modified in patients in whom thestenosis affects the mucosa overlying the cricoid plate.Sparing the posterior cricoid plate preserves the recurrentlar yngeal nerves The line of mucosal division isperformed high on the posterior cricoid plate to exciseinvolved mucosa and submucosa (Figure 17-11) Mucosalresection stops short of the superior border of the cricoidplate, immediately below the arytenoid cartilages Therostrum or “prow” of the proximal tracheal cartilage isshaped as described above, but posteriorly a broad-basedflap of membranous wall is fashioned, which is advanced

to resurface the denuded posterior criciod plate Theposterior portion of the anastomosis is made with inter-rupted 4-0 Vicryl sutures placed only through the fullthickness of mucosa and submucosa of the posterior wall

of the larynx, and then through the full thickness of themembranous wall of the trachea (Figure 17-12), inverted

so that the suture knots lay external to the lumen Foursutures are placed through the cartilaginous portion ofthe inferior margin of the cricoid plate and the outerportion of the membranous wall of the trachea below theproximal edge of the flap in order to fix the membranouswall to the inferior edge of the cricoid plate When thelesion extends proximally toward the conus elasticus, it isnecessary to accept some residual narrowing because ofthe height of the anastomosis

Lower Tracheal and Carinal Resections

While isolated benign strictures of the lower trachea andcarina are seen, the most common lesions requiringsurgery are tumors Therefore, the principles of surgicaloncology must be strictly applied to most of these resec-tions Patients with bronchogenic carcinoma and N2disease should be considered to have unresectabledisease, and surgery should only be performed in aprotocol setting.23–26Mediastinoscopy is performed on theday of proposed surgery not only to assess nodal statusand resectability, but to facilitate the resection and recon-struction by mobilizing the pretracheal plane while visu-alizing the recurrent laryngeal nerve Scarring of thepretracheal plane from prior mediastinoscopy limitsairway mobility, complicates reconstruction, andincreases the likelihood of injury to the left recurrent

222 / Advanced Therapy in Thoracic Surgery

generous caudal displacement of the trachea For this

reason, end-to-end anastomosis of trachea to the left

main stem with reimplantation of the right into the

trachea is more commonly employed A right hilar

release maneuver facilitates this procedure More

exten-sive resections require end-to-end anastomosis of trachea

to right main stem with reimplantation of left into the

bronchus intermedius This obviates the need for

exten-sive left main stem mobility When there is extenexten-sive

endobronchial involvement, excessive lung destruction,

or invasion of hilar vessels, then carinal (sleeve)

pneu-monectomy is necessary Experienced intraoperative

judgment is required to determine the ideal approach

The anastamosis is fashioned with interrupted simple

4-0 Vicryl sutures placed with knots tied outside the

lumen Once reconstructed, the anastomoses are tested

for air tightness to 40 cm of water All suture lines are

circumferentially wrapped with pedicled flaps of

pericar-dial fat or a broad-based pleural flap In high-risk

patients, especially those who have undergone prior

radiotherapy, an intercostal flap stripped of all

perios-teum or an omentum pedicle is used These flaps not

only buttress the anastomoses, but more importantly,

separate them from the hilar vessels, helping to prevent

bronchovascular fistulas

Release Procedures

When extensive resections are required the standard

methods of mobilization by dissection in the pretracheal

plane and flexion of the neck often do not allow a

tension-free anastomosis In these instances, further

mobilization with “release” procedures is required In our

experience, this has been necessary in 8.3% of patients

undergoing resections for postintubation stenosis and

15% of patients undergoing resections for tumors.18

Certain release maneuvers are more effective for

achiev-ing additional mobility of the cervical trachea, whereas

others are more effective for freeing the intrathoracic

trachea

In resection of the upper trachea, additional length

may be gained by releasing the lar ynx with a

Montgomery suprahyoid release.27This consists of

divid-ing the muscles that insert on the superior aspect of the

central part of the hyoid bone The hyoid itself is then

divided just medial to its lesser cornua on either side, and

the stylohyoid tendons are divided (Figure 17-13) This

provides an additional approximately 1.5 cm of length It

is important to realize that laryngeal release maneuvers

may predispose patients to postoperative aspiration,

especially of liquids In time, however, this problem has

resolved in virtually all patients

For intrathoracic tracheal or carinal resections, tional length is best achieved by hilar release.2 8

addi-Mobilization of the right hilum should be done first,along with division of the inferior pulmonary ligament.Then, a U-shaped incision is made in the pericardiumbelow the inferior pulmonary vein If required, the peri-cardium can be incised 360° around the hilus for maxi-mal mobility In this event, the vascular and lymphaticpedicle to the main stem bronchus is left preservedbehind the pericardium The left hilum may be similarlymobilized (Figure 17-14) in the unusual case whereunilateral mobilization is insufficient However, left-sidedhilar release can only be accomplished easily through amedian sternotomy by opening the pericardium anteri-orly, bilateral thoracotomies, or an extended clamshellincision As with most airway surgery, neck flexion ishelpful Laryngeal release has not been shown to producemeaningful mobility at the level of the carina.29

Tracheal Resection in an Irradiated Field

In patients who have received radiation therapy prior tocoming to surgical resection, the risk of anastomoticdehiscence is increased The detrimental effects of irradi-ation on tissue and, more specifically, tracheal healinghave been amply demonstrated in animals The earlyMassachusetts General Hospital experience with trachealresection in patients who had received high doses of radi-ation, particularly when this occurred remotely in time,confirmed these findings.30 In these patients there was amarkedly increased incidence of anastomotic failure.When a patient has received either high-dose irradia-tion (more than 4,500 cGy) or who has undergone irra-Techniques of Tracheal Resection and Reconstruction / 225

FIGURE 17-13 The dotted lines indicate the point where the hyoid

bone is divided, separating its body from the greater horn on each side Reprinted with permission from Montgomery ww 27

A collar incision is performed which circumscribes

the stoma (Figure 17-16) Dissection identical to that

described above for simple tracheal resection is

performed up to the point of division of the trachea

below the fistula As the posterior wall of the trachea is

dissected from inferior to superior, the fistulous tion is isolated circumferentially It is detached from theesophagus with a small rim of normal esophageal tissueand kept attached to the tracheal segment with which itwill be removed (Figure 17-17) After removal of thespecimen, the esophagus is closed longitudinally withtwo layers of 4-0 silk (Figure 17-18A and B) The ster-nohyoid or sternothyroid muscle is sutured into place tobuttress the esophageal closure and interpose healthytissue between the esophageal and tracheal suture lines(Figure 17-19) The end-to-end tracheal anastomosis isthen performed as described previously If the fistulousopening is long and the tracheal wall is not circumferen-tially damaged as far down as the fistula extends, themargin of the tracheal opening may be excised as a V andrepaired with a vertical suture line prior to creating theend-to-end tracheal anastomosis In the rare case wherethere is no significant damage to the trachea associatedwith the fistula, tracheal resection is unnecessary, andsimple esophageal and tracheal repair with musclebuttress is performed

connec-Postoperative Issues

The patient’s postoperative course is largely determined

by intraoperative technique The goals of both ative and postoperative care are the maintenance of goodpulmonary toilet and the promotion of anastomoticTechniques of Tracheal Resection and Reconstruction / 227

intraoper-FIGURE 17-16 Exposure for most tracheoesophageal fistulas is through a low collar incision Occasionally, a partial upper sternotomy is required

for more distal exposure of the trachea Reprinted with permission from Mathisen DJ et al 31

FIGURE 17-15 Endoscopic view of tracheoesophageal fistula.

dure Postoperatively, these include minimizing fluids,

elevating the head of the bed and administering racemic

epinephrine to help prevent laryngeal edema Rarely, an

especially high laryngotracheal resection will cause

enough laryngeal edema to necessitate one or two doses

of steriods to avoid impending re-intubation and/or

tracheostomy Heliox, with its low viscosity, is sometimes

useful in these circumstances since it can occasionally

gain enough time for the other maneuvers to take effect

The patient is cautioned against unnecessary speech

during this period, as it can contribute to the laryngeal

edema

Cervical flexion is maintained with the chin-to-chest

suture for 5 to 7 days, after which time the patient is

advised not to extend the neck for another week Before

removing the chin-to-chest suture, we routinely examine

the anastomosis with a flexible bronchoscope or obtain

tracheal tomograms to assure normal healing

Oral alimentation is begun cautiously, particularly in

patients who have undergone a laryngeal release Water is

offered initially, since its aspiration is better tolerated and

more easily dealt with than more substantial foods

Results and Complications

Results of tracheal resection have been impressive For

simple resections of postintubation stenoses, including

our earliest experience and reoperations, of 503 patients

there were only 12 deaths and 18 failures.32

Four-hundredand forty (87%) had good and 31(6%) satisfactory

results Of 80 patients undergoing laryngotracheal

resec-tions for all causes of subglottic stenosis, there was one

postoperative death Results were excellent in 18 (22%),

good in 52 (65%), and satisfactory in 8 (10%) In only

two patients was there failure to achieve a functional

airway

For primary tumors of the trachea, for which

resec-tion and reconstrucresec-tion was performed, including carinal

resections, there were 6 deaths in 132 patients.11Five of

the six were following the more complex carinal

proce-dures Six patients developed significant postoperative

restenosis, but all of these underwent successful

re-resection The oncologic outcomes of patients with

bronchogenic carcinoma has recently been separated out

for carinal resections and reported by Mitchell and

colleagues.26 In this series of bronchogenic carcinomas,

57% presented with N0 disease, 25% had N1 disease, and

18% had N2 or N3 disease The overall 5-year survival

was 42% Lymph node status strongly influenced

survival The 5-year survival of N0, N1, and N2 or N3

patients was 51%, 32% and 12%, respectively (see

Figure 17-3) Microscopically positive margins did not

affect survival Isolated carinal resection resulted in a

more favorable prognosis than more extensive resections,with a 5-year survival of 51%

The long-term survival data for resected adenoid cysticcarcinoma of the trachea and carina have not been as welldefined, partly because of the proclivity for late recur-rence The published experience of all tracheal adenoidcystic carcinomas, which includes carinal, suggests amuch more favorable prognosis than bronchogenic carci-nomas Lymph node and margin status do not appear tosignificantly affect survival.11,12,23Postoperative radiationtherapy is recommended in all cases of adenoid cystic orbronchogenic carcinoma, unless contraindicated byperformance status or anastomotic complications Therole of chemotherapy has not been established

Secondary cancers arising in the thyroid and invadingthe trachea have also been resected with good results Of

27 patients undergoing resection and reconstruction ofthe trachea for thyroid cancer invading the airway,including patients with both simple and complex laryn-gotracheal reconstructions, two died in the postoperativeperiod, one had a short segment tracheal necrosis requir-ing re-resection, and all others were provided with anadequate airway by their initial operation Only twopatients experienced an airway recurrence.13

In patients who have received radiation therapy prior

to coming to surgical resection, the risk of anastomoticdehiscence is increased Nineteen patients have undergonetracheal resections with vascularized tissue coverage atMassachusetts General Hospital following radiation ther-apy.30Fifteen had a pedicied omental flap, 1 a pericardialfat pad flap, 1 an intercostal muscle flap, and 2 a pleuralflap Only one of these patients suffered an anastomoticdehiscence, and this resulted in death Another patientrequired a T-tube Following development of a paratra-cheal abscess, he ultimately died of recurrent squamouscell carcinoma Two patients developed wound infectionsthat responded to treatment Overall, 15 patients experi-enced an excellent result without dyspnea, and 2 experi-enced a good result with dyspnea with moderate exercise.Our experience with the repair of tracheoesophagealfistulas involves the performance of 41 operations on 38patients.31 Simple division and closure of the fistula wasdone in nine patients Tracheal resection and reconstruc-tion was combined with esophageal repair in the remain-der The esophageal defect was closed in two layers and aviable strap muscle interposed between the airway andesophageal suture lines in all cases There were fourdeaths (11%) Three patients developed recurrent fistulasand one patient suffered a delayed tracheal stenosis Allwere successfully managed with re-operation Of the 34survivors, 33 can swallow normally, and 32 breathe with-out the need for a tracheal appliance

Techniques of Tracheal Resection and Reconstruction / 229

Despite these encouraging outcomes, complications do

occur They have generally been few for upper tracheal

resections Major complications more often have

followed carinal or laryngotracheal resections

Inability to clear secretions with consequent

atalecta-sis is the most common, though relatively minor,

compli-cation and this can be handled as described above This

management has limited the number of patients who

have suffered pneumonia or respiratory failure after

simple tracheal resection Laryngeal edema may occur

after procedures involving the larynx, but this generally

regresses in approximately one week when treated as

described above Unilateral recurrent laryngeal nerve

injury rarely occurs as a result of extensive resection,

usually in patients with tracheal tumors

The most common late complication has been the

formation of granulomas at the suture line This is

usually manifest as wheezing or minor hemoptysis It has

occurred more commonly following resection for

inflam-matory lesions than for tumor, as residual inflammation

may be present in such cases despite efforts to wait out

the acute inflammatory phase Granulations can be

managed by bronchoscopic removal under light

anesthe-sia Often a suture is found to have migrated into the

lumen at the base of the granulation, and in such cases

removal of the suture leads to ultimate healing In some

cases, however, multiple bronchoscopies are necessary

over a period of time The current use of Vicryl rather

than nonabsorbable sutures has almost eliminated this

once common problem

Suture line separation, the most dreaded

complica-tion, is almost invariably related to tension on the

anasto-mosis or compromise of its blood supply These

problems, which occur most commonly following

resec-tion of long segments of trachea and following radiaresec-tion,

are more frequently associated with resection for tumor

than for postintubation stenosis Steroid use which has

not been discontinued preoperatively has also been

asso-ciated with anastomotic failure Early, minimal air

leak-age at the suture line may seal without sequelae and can

be managed with closed suction drains True separation,

however, is usually heralded by respiratory distress

Anastomotic separation in the immediate

postopera-tive period suggests a serious technical error, and

reoper-ation under these conditions is appropriate Early

separation that does not appear remediable by resuturing

or a local muscle flap can be temporized by placement of

a tracheostomy or a Montgomery T-tube, with corrective

surgery to be performed months later after regression of

the acute inflammatory response Sometimes, with such a

tube serving as a stent, the partial restenosis that results

may leave a tolerable airway, and this may be improvedwith endoscopic dilations

Stenosis may occur at the anastomotic site after theinitial postoperative period, without evidence of a frankseparation This can be managed temporarily by rigidbronchoscopic dilation Ultimately, most of thesepatients will require re-resection This should be done nosooner than 4 months after the initial procedure in order

to allow time for regression of inflammation

Other rare complications that we have seen includefatal hemorrhage from the pulmonary artery, likelyrelated to erosion from an adjacent tracheobronchialanastomosis, innominate artery hemorrhage, tracheo-esophageal fistula, esophagocutaneous fistula, empyema,and quadriplegia, which may have been related to over-flexion of the chin to the chest

Tracheal Substitutes and Tracheal

Transplantation

The advancement of techniques in tracheal surgery haveallowed up to 50% of the trachea to be resected in favor-able patients This has rendered the majority of tracheallesions requiring surgical treatment correctable with asingle-staged resection and reconstruction On rare occa-sions, the extent of a lesion involves more of the tracheathan can be safely reconstructed with a primary end-to-end anastomosis These situations have lead investigators

to attempt to reconstruct the trachea with prostheticmaterial

Early designs focused on solid tubes anastomosed to-end with the trachea Neville and colleagues were one ofthe first to report a small series on human subjects.33

end-Results were dismal The nonporous silicone tubes failed

to become incorporated with tissue and thus becameinfected and either extruded into the airway or eroded intothe surrounding vascular structures To avoid this fate,subsequent designs employed porous cylinders, usuallyfabricated from metal wire of all different elements andalloys These prosthetic conduits were usually wrappedwith an omental or muscle flap and then placed as aninterposition graft in the trachea The tissue flap wasexpected to provide an airtight seal and serve as a source ofvascularized tissue in which the prosthesis would becomeincorporated and protected from the surrounding greatvessels Most of the investigations were in animals, andwhile the prostheses became successfully incorporated,they ultimately failed as the animals became obstructedfrom granulation tissue.34–37The lack of an epithelialsurface essentially created an open festering woundencouraging granulation tissue to proliferate unchecked,resulting in airway stenosis Small segments of tracheacould be successfully replaced in this manner, since respi-

230 / Advanced Therapy in Thoracic Surgery

ratory epithelium would migrate for 1 to 2 cm from either

anastomosis to cover the replaced portion of the airway In

larger segments, the respiratory epithelium would either

not migrate such a distance or simply could not cover the

distance fast enough to outpace and thus quell the

exuber-ant granulation tissue Recent investigators have supplied

an epithelial lining by grafting either oral mucosa or

split-thickness skin grafts on the inner surface of the porous

prosthesis.38These require a two-staged procedure where

the pedicled tissue or prosthesis composite is created and

allowed to mature before it is transposed as an

interposi-tion tracheal substitute Early results are encouraging, but

their complexity and inconsistent results make their

clini-cal application unfeasible at this time

The lack of success with prosthetic tracheal

replace-ments has encouraged many investigators to pursue an

airway conduit made of all biological tissue, either viable

allotransplantation or cryopreserved tracheas Neither

approach has achieved meaningful success

Tracheal transplantation suffers from several major

limitations First, the trachea lacks a single, sizable

venous and arterial system Instead, its vascular supply

consists of multiple small vessels too fine to anastomose

To overcome this limitation, investigators have used the

omentum to wrap tracheal transplants to allow for

vascular ingrowth.39,40 However, results have been mixed,

especially with longer segments Second, unlike most

other solid organ transplants, the trachea by virtue of its

anatomical location is exposed to a heavy concentration

of antigens and microorganisms The result is an

ischemic tracheal transplant, heavily contaminated with

oropharyngeal microorganisms, in an

immunodebili-tated patient Finally, many of the conditions which

involve the entire trachea are benign processes that are

safely managed with Silastic T-tubes and thus do not

justify the detrimental effects of immunosuppressive

therapy In those cases where a malignant tracheal tumor

requires resection of the entire trachea,

immunosuppres-sive therapy should be avoided as well

In a move to avoid immunosuppressant therapy,

investigators have begun to test methods of rendering

allogenic tracheal grafts less or nonantigenic The most

important transplant antigens involved in graft rejection

are expressed by the major histocompatibility complex

(MHC) In the trachea, the mucosa and the submucosal

glands express MHC-I and MHC-II.41Cartilage does not

express MHC antigens and is an immunologically

privi-leged tissue that has been successfully used in

allo-transplantation for years without the use of

immunosuppressive therapy It is believed that the thick,

avascular proteoglycan-collagen matrix that encapsulates

the chondrocytes, shields them from recognition by the

immune system Moreover, since cartilage has no

capil-lary blood supply and survives from diffusion it cansurvive off the diffusion to and from an omental wrap.Investigators have designed methods to process freshtracheas to remove the tracheal mucosa and submucosalglands while preserving the viability of the cartilage.42,43Inpilot dog studies, these grafts epithelialize and maintainviable cartilage without significant stenosis for up to oneyear Control animals, which had the same procedureusing a fresh unprocessed trachea instead, developednecrosis and stenosis over a few weeks Others have usedcryopreservation techniques to achieve similar resultssince cartilage tends to survive the process and themucosa and glands do not.44,45The results of these studiesare encouraging because they demonstrate that a viabletracheal conduit can be transplanted, integrated, andaccepted by the host and re-epithelialized However, thesestudies were done for small segments of tracheal replace-ment, where the epithelium can be expected to migratefrom the anastomotic ends and resurface the graft Sincethis form of therapy will be used to treat near total ortotal tracheal replacement, these methods will need to betested on longer segments

Summary

In conclusion, techniques of tracheal resection andreconstruction have advanced to a point where theseprocedures can be done with the anticipation of goodresults and an acceptable level of morbidity and mortal-ity Nonsurgical methods such as dilation, ablation, orstenting do not currently offer cure of tracheal stenoses,although these may each play a role in palliation ortemporization prior to surgery The current standard ofcare dictates that symptomatic benign tracheal stenosesthat can be resected should be resected For primarymalignant tumors, squamous cell carcinomas should beresected when complete resection for cure is anticipated,while patients with the more indolent adenoid cysticcarcinoma may benefit from even palliative resectionwith microscopically positive margins Tracheal resectionfor low-grade thyroid carcinomas invading the airwayshould also be performed for cure or palliation, some-times even in the presence of distant metastasis Thedevelopment of successful techniques of completetracheal replacement in humans is an area of ongoingresearch but currently has no clinical applicability

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11 Grillo HC, Mathisen DJ Primary tracheal tumors:

treat-ment and results Ann Thorac Surg 1990;49:69–77.

12 Regnard JF, Fourquier P, Levasseur P, et al Results and

prognostic factors in resections of primary tracheal tumors:

a multicenter retrospective study J Thorac Cardiovasc Surg

1996;111:808–14.

13 Grillo HC, Suen HC, Mathisen DJ, Wain JC Resectional

management of thyroid carcinoma invading the airway.

Ann Thorac Surg 1992;54:3–9.

14 Grillo HC, Mark EJ, Mathisen DJ, Wain JC Idiopathic

laryngotracheal stenosis and its management Ann Thorac

Surg 1993;56:80–7.

15 Ashiku SK, Kuzucu A, Grillo HC, et al Idiopathic

cheal stenosis: effective definitive treatment by

laryngotra-cheal resection J Thorac Cardiovasc Surg 2004;127:99–107.

16 Weber AL, ed Symposium on the larynx and trachea.

19 Mathisen DJ, Grillo HC Endoscopic relief of malignant

airway obstruction Ann Thorac Surg 1989;48:469–75.

20 Wilson RS Tracheal resection In: Marshall BE, Longnecker

DE, Fairley HB, editors Anesthesia for thoracic procedures.

Boston (MA): Blackwell Scientific; 1988 p 415–32.

21 Grillo HC Primary reconstruction of the airway after resection of subglottic and upper tracheal stenosis Ann Thorac Surg 1982;33:39–58.

22 Grillo HC, Mathisen DJ, Wain JC Laryngotracheal tion and reconstruction for subglottic stenosis Ann Thorac Surg 1992;53:54–63.

resec-23 Grillo HC Carinal neoplasia In: Grillo HC, Austen WG, Wilkins EW, et al, editors Current therapy in cardiotho- racic surgery Hamilton (ON): BC Decker Inc; 1989 p 134.

24 Mathisen DJ, Grillo HC Carinal resection for bronchogenic carcinoma J Thorac Cardiovasc Surg 1991;102:16–22.

25 Mitchell JD, Mathisen DJ, Wright CW, et al Clinical ence with carinal resection J Thorac Cardiovasc Surg 1999;117:39–53.

experi-26 Mitchell JD, Mathisen DJ, Wright CW, et al Resection of bronchogenic carcinoma involving the carina: long-term results and the effect of nodal status on outcome J Thorac Cardiovasc Surg 2001;121:465–71.

27 Montgomery WW Suprahyoid release for tracheal mosis Arch Otolaryngol 1974;99:255–60.

anasto-28 Newton JR, Grillo HC, Mathisen DJ Main bronchial sleeve resection with pulmonary conservation Ann Thorac Surg 1991;52:1272–80.

29 Grillo HC Carinal Neoplasia In: Grillo HC, Austen WG, Wilkins EW, et al editors Current therapy in cardiotho- racic surgery Hamilton (ON): B.C Decker Inc.; 1989.

p 134.

30 Muehrcke DD, Grillo HH, Mathisen DJ Reconstructive airway operation after irradiation Ann Thorac Surg 1995;59:14–8.

31 Mathisen DJ, Grillo HC, Wain JC, Hilgenberg AD Management of acquired nonmalignant tracheoesophageal fistula Ann Thorac Surg 1991;52:759–65

32 Grillo HC, Donahue DM, Mathisen DJ Postintubation tracheal stenosis: treatment and results J Thorac Cardiovasc Surg 1995;109:486–93.

33 Neville We, Bolanowski JP, Kotia GG Clinical experience with the silicone tracheal prosthesis J Thorac Cardiovasc Surg 1990;99:604–12.

34 Teramanchi M, Nakamura T, Yamamoto Y Porous-type tracheal prosthesis sealed with collagen sponge Ann Thorac Surg 1997;64:965–9.

35 Satoh S, Elstrodt J, Hinrichs WL, Feinjen J Prevention of infection in porous tracheal prosthesis by omental wrap- ping ASAIO Trans 1990;36:M438–40.

36 Schauwecker HH, Gerlach J, Planck H Isoelastic polyurethane prosthesis for segmental tracheal replacement

in beagle dogs Artif Organs 1989;13:216–8.

37 Teramachi M, Kiyontani T, Takimoto Y A new porous tracheal prosthesis sealed with collagen sponge ASAIO Trans 1995;41:M306–10.

232 / Advanced Therapy in Thoracic Surgery

38 Suh SW, Kim J, Baek CH Development of new tracheal

prosthesis: atogenous mucosa-lined prosthesis made from

polypropylene mesh Int J Artif Organs 2000;23:261–7.

39 Li J, Xu P, Chen H Successful tracheal autotransplantation

with two-staged approach using greater omentum Ann

Thorac Surg 1997;64:199–202.

40 Park YS, Lee DY, Paik HC The role of omentopexy in

tracheal transplantation in dogs Yonsei Med J

1996;37:118–24.

41 Bujia J, Wilmes E, Hammer C Tracheal transplantation:

demonstration of HLA class II subregion gene products on

human trachea Acta Otolaryngol 1990;110:149–54.

42 Liu Y, Nakamura T, Yamamoto Y Immunosuppressant-free

allotransplanation of the trachea: the antigenicity of

tracheal grafts can be reduced by removing the epithelium and mixed glands from the graft by detergent treatment J Thorac Cardiovasc Surg 2000;120:108–14.

43 Yokomise H, Inui K, Wada H High-dose irradiation prevents rejection of canine tracheal allografts J Thorac Cardiovasc Surg 1994;107:1391–7.

44 Mukaida T, Shimizu N, Aoe M Origin of regenerated epithelium in cryopreserved tracheal allotransplantation Ann Thorac Surg 1998;66:205–8.

45 Mukaida T, Shimizu N, Aoe M Experimental study of tracheal allotransplantation with cryopreserved grafts J Thorac Cardiovasc Surg 1998;116:262–6.

Techniques of Tracheal Resection and Reconstruction / 233

Pulmonary arteriovenous malformations (PAVMs) are

vascular lesions of the lung in which there is an abnormal

connection between the pulmonary arterial and venous

systems without an intervening capillary bed PAVM has

been described under a variety of pseudonyms including

benign cavernous hemangioma, pulmonary

arteriove-nous angiomatosis, hamartomatous angioma of the lung,

arteriovenous aneurysm, and arteriovenous fistula.1The

malformation leads to shunting of unoxygenated blood

into the systemic circulation and may permit embolic

material to pass unfiltered through the lungs PAVMs are

classified into simple or complex A simple PAVM has a

single feeding vessel, and a complex PAVM has multiple

feeding vessels

PAVM was first described in 1897 by Churton in a

12-year-old child.2The first surgical intervention was reported

by Shenstone who performed a pneumonectomy for a

large central lesion.3Several publications from our

institu-tion have focused on the surgical management of PAVM

and most recently on the angiographic management.1,4–7

PAVM occurs more commonly than previously

thought It occurs with an incidence of 1 in 2,351 to 1 in

39,000 individuals.8The male-to-female incidence is

equal; they are bilateral in 8 to 20% and multiple in 30 to

50% of patients.9While PAVM can present as isolated

pulmonary findings, it is often associated with hereditary

hemorrhagic telangiectasia (HHT), also known as theRendu-Osler-Weber syndrome In fact, up to 87% ofPAVMs are found in patients with HHT, and approxi-mately 20% of patients with HHT develop PAVMs.7

Although the overwhelming majority of PAVM iscongenital in origin, secondary or acquired PAVM canoccur The causes of acquired PAVM include trauma,actinomycosis, schistosomiasis, cirrhosis, systemicamyloidosis, mitral stenosis, and metastatic carcinoma.1

Although some patients with PAVM are matic, most patients are symptomatic Clinical features in

asympto-a recent Masympto-ayo Clinic series asympto-are shown in Tasympto-able 18-1 Themost common pulmonary symptom is dyspnea, and thiscorrelates with the degree of shunting Dyspnea can in-crease with a change in position from supine to uprightand with exercise because of increased blood flow to theTABLE 18-1 Clinical Features in 93 Patients with

Pulmonary Arteriovenous Malformation

Clinical Feature Number (%) Dyspnea 53 (57) Cyanosis 27 (29) Clubbing 18 (19) Cerebrovascular event 17 (18) Asymptomatic 15 (16) Hemoptysis 14 (15) Transient ischemic attack 11 (12) Cerebral abscess 5 (5) Seizure 5 (5) Adapted from Swanson KL et al (1999) 7

lower portion of the lungs where PAVMs are usually

located Depending on the degree of right-to-left

shunt-ing, the hypoxemia may be refractory to supplemental

oxygen Other clinical features include cyanosis,

club-bing, and hemoptysis The classic triad of dyspnea,

cyanosis, and clubbing is found in 30% of adults.1

Neurologic events are common with PAVM and include

embolic disorders such as transient ischemic attacks and

strokes Dines and colleagues found a stroke to have

occurred in 10% of all untreated patients followed for 4

to 10 years.5Cerebrovascular events can also occur due to

sludging secondary to polycythemia and complications

from concomitant cerebral lesions Seizures and cerebral

abscesses also occur In addition to the possible physical

findings of cutaneous telangiectasia, cyanosis, and

club-bing, a pulmonary bruit is present in 34% of patients.7

The characteristic finding on a plain chest radiograph

is a circumscribed, lobulated density Most PAVMs are

located in the lower lobes and often are peripheral

Occasionally a feeding vessel can be seen on the chest

radiograph (Figure 18-1) Currently, spiral computed

tomography (CT) offers the least invasive and least

expensive way to establish the presence of PAVM

(Figure 18-2) If thin sections are utilized, intravenous

contrast is not necessary to establish the diagnosis of

PAVM; however, contrast is required in order to provepatency CT can elicit the number and size of the fistulas,and afferent and efferent vessels can be identified.However, unless the feeding artery or draining vein areidentified, a PAVM cannot be distinguished from apulmonary nodule.1Magnetic resonance imaging (MRI)may be helpful but is less sensitive Oxygen saturationshould be measured to see if there is significant shunting.Two-dimensional contrast echocardiography with indo-cyanine dye or the injection of agitated saline can beuseful in establishing the diagnosis and is less invasivethan angiography.10,11Furthermore, contrast echocardiog-raphy is useful in pregnant women, in whom ionizingradiation may be dangerous The technique of contrastechocardiography involves the injection of agitated salineinto a peripheral vein The appearance of a cloud of bub-bles in the left atrium confirms right-to-left shunting Airbubbles will not survive a normal capillary bed, and if apatent foramen ovale has been excluded in the appropri-ate clinical setting, PAVM can be suspected.1Angiography

is the definitive test and can clearly outline the anatomy

of PAVM (Figure 18-3) Pulmonary angiography fies the location, size, and number of PAVMs.Additionally, it defines their blood supply and differenti-ates simple from complex PAVMs.7

identi-Almost all patients with PAVM should be treated.Untreated PAVMs are associated with an 11% mortalityand 26% morbidity rate.5Asymptomatic patients with asingle small (< 1 cm) PAVM occasionally will beobserved; however, the risk of embolic stroke is increased

in these patients There are a few patients with severepulmonary artery hypertension who would develop rightManagement of Pulmonary Arteriovenous Malformations and Sequestrations / 235

FIGURE 18-1 Chest radiograph in a 34-year-old female patient

demonstrating a large feeding vessel supplying a pulmonary

arterio-venous malformation in the lower lung field (black arrow) The vessel

can be seen just medial to the left heart border, coursing to the lower

lung fields (white arrow).

FIGURE 18-2 Computerized tomography of the chest with

intra-venous contrast In the lung window settings, multiple pulmonary

arteriovenous malformations are seen (arrows) With permission from

Swanson KL et al 7

more coils than balloons must often be placed to achieve

satisfactory occlusion.1In our recent series of patients

treated with angiographic embolization, 91% responded

favorably as shown by an improvement in their

symp-toms or arterial blood gas analysis The mean PaO2rose

from a preembolization level of 56 mm Hg to 77 mm Hg

postembolization.7

Long-term follow-up is recommended in all patients

with PAVM Even after successful treatment, there can be

growth of smaller lesions and recanalization of

success-fully embolized lesions Recurrences can be successsuccess-fullyreembolized Our recommendations for follow-upinclude an annual physical exam, chest radiograph,arterial blood gas analysis, and assessment of the right-to-left shunt if symptoms are present.7

Pulmonary Sequestration

Pulmonary sequestration covers a spectrum of relateddevelopmental pulmonar y anomalies It was firstdescribed simultaneously by Rokitansky and Rektorzik in

1861.20,21The term “sequestration” was first used by Pryce

and is derived from the Latin verb sequestrare, to

separate.22The lung is, in effect, sequestered from theremainder of the lung It is defined as a segment of lungthat has no bronchial communication with the rest of thelung.23,24The arterial supply comes from systemic circula-tion, including from the thoracic aorta, abdominal aorta,

or intercostal arteries The venous return is either to thepulmonary system or to the systemic circulation Se-questrations are different from accessory pulmonarylobes, which are separated from the normal lung bypleural investments but maintain a normal communica-tion with the tracheobronchial tree Surgical interest inthese lesions first arose when Harris and Lewis reported

on an operative death resulting from injury to an anomalous artery supplying the lower lobe of the lung in

a 5-year-old child.25

Pulmonary sequestrations are thought to arise asaccessory lung buds that then migrate along with thedeveloping esophagus This may account for their variableblood supply and occasional foregut communication.Other authors believe that these anomalies are acquiredand are the result of chronic infections The latter viewdoes not explain the fact that the lesion is often diagnosedantenatally without evidence of infection.26They aredivided into two types: the more common intralobarsequestration and extralobar sequestration In intralobarsequestration, the sequestered portion of lung is situatedwithin normal lung parenchyma sharing a commonvisceral pleural envelope In extralobar sequestration, thesequestered portion has its own visceral pleural liningseparating it from the remaining lung tissue Reporting on

233 patients with both intralobar and extralobar trations, Carter found a 2:1 ratio favoring the left side,and for extralobar sequestrations, a 3:1 male-to-femaleratio.27More recently, Savic and colleagues found nogender-specific distribution in either intralobar orextralobar sequestrations.2 8Table 18-2 summarizescommon features of sequestrations

seques-Extralobar sequestrations are typically shaped and usually sit next to the aorta in the inferiorportion of the chest Forty percent of these patients have

pyramid-Management of Pulmonary Arteriovenous Malformations and Sequestrations / 237

FIGURE 18-4 Pulmonary angiogram after coil embolization (arrow).

Stoppage of blood flow through the fistula is seen With permission

from Swanson KL et al 7

FIGURE 18-5 Chest radiograph after multiple coil embolizations.

Each group of coils represents a separate pulmonary arteriovenous

malformation (PAVM) A large PAVM was embolized in the right upper

lobe With permission from Swanson KL et al 7

cations For extralobar sequestration, this usually means

removing just the extralobar segment, securely ligating

the arterial and venous supply For an intralobar

seques-tration a segmentectomy can be performed, but chronic

infection often makes this technically impossible, and a

lobectomy is thus required Extra care should be taken

when identifying and ligating the arterial supply since it

has been reported that this vessel can retract underneath

the diaphragm and lead to an exsanguinating

hemor-rhage.2 5 It is possible to remove carefully selected

pulmonary sequestrations videothoracoscopically

Retroperitoneal or intra-abdominal sequestrations may

require a laparotomy or a thoracoabdominal approach

The treatment of patients when an antenatal diagnosis is

made depends on the size of the lesion and the secondary

pathophysiologic effects In Becmeur and colleagues’

analysis of 10 antenatally diagnosed cases, 2 fetal

interven-tions were necessary: paracentesis of ascites and amniotic

fluid in one fetus and placement of a pleuroamniotic

shunt for hydrothorax in another All 10 patients

under-went surgery after birth with no mortality and minimal

morbidity.40 Fortunately, sequestrations occur only on a

sporadic basis; therefore, parents of an infant with

seques-tration should be counseled that it is not hereditary

References

1 Pick A, Deschamps C, Stanson AW Pulmonary

arteriove-nous fistula: presentation, diagnosis, and treatment World

4 Gomes MR, Bernatz PE, Dines DE Pulmonary

arteriove-nous fistulas Ann Thorac Surg 1969;7:582.

5 Dines DE, Arms RA, Bernatz PA Pulmonary arteriovenous

fistulas Mayo Clin Proc 1974;49:460.

6 Dines DE, Seward JB, Bernatz PA Pulmonary

arteriove-nous fistulas Mayo Clin Proc 1983;58:176.

7 Swanson KL, Prakash UB, Stanson AW Pulmonary

arteri-ovenous fistulas: Mayo Clinic experience, 1982–1997 Mayo

Clin Proc 1999;74:671.

8 Marchuk DA The molecular genetics of hereditary

hemor-rhagic telangiectasia Chest 1997;111(Suppl):79S.

9 Mitchell RO, Austin EH III Pulmonary arteriovenous

malformation in the neonate J Pediatr Surg 1993;28:1536.

10 Shub C, Tajik AJ, Seward JB, Dines DE Detecting

intrapul-monary right-to left shunt with contrast echocardiography:

observation in a patient with diffuse pulmonary

arteriove-nous fistulas Mayo Clin Proc 1976:51:81.

11 Bradshaw DA, Murray KM, Mull NH Massive hemoptysis

in pregnancy due to a solitary pulmonary arteriovenous malformation West J Med 1994:161:600.

12 Puskas JD, Allen MS, Moncure AC, et al Pulmonary ovenous malformations: therapeutic options Ann Thorac Surg 1993;56:253.

arteri-13 Porstmann W Therapeutic embolization of arteriovenous fistula by catheter technique In: Kelop O, editor Current concepts in pediatric radiology Berlin: Springer; 1977.

arte-16 Haijema TJ, Overtoom TTC, Westermann CJJ, Lammers JWJ Embolization of pulmonary arteriovenous malformations: results and follow-up in 32 patients Thorax 1995;50:719.

17 Pollak JS, Egglin TK, Rosenblatt MM, et al Clinical results

of transvenous systemic embolotherapy with a logic detachable balloon Radiology 1994;191:477.

neuroradio-18 Jackson JE, Whyte MKB, Allison DJ, Hughes JMB Coil embolization of pulmonary arteriovenous malformations Cor Vasa 1990;32:191.

19 Dutton JAE, Jackson JE, Hughes JMB, et al Pulmonary riovenous malformations: results of treatment with coil embolization in 53 patients Am J Roentgenol 1995;165:1119.

arte-20 Rokitansky C Lehrbuch der Pathologischen Anatomie 3rd

23 Pryce DM Lower accessory artery with intralobar tration of the lung J Pathol Bacteriol 1946;58:457–67.

seques-24 Pryce DM, Sellors TH, Blair LG Intralobar sequestration of the lung associated with an abnormal pulmonary artery Br

J Surg 1947;35:18–29.

25 Harris HA, Lewis I Anomalies of lungs with special ence to danger of abnormal vessels in lobectomy J Thorac Cardiovasc Surg 1940;9:666.

refer-26 Holder PD, Langston C Intralobar pulmonary tion (a nonentity?) Pediatr Pulmonol 1986;2:147–53.

sequestra-27 Carter R Collective review: pulmonary sequestrations Ann Thorac Surg 1969;7:68–8.

28 Savic B, Birtel FJ, Tholen W, et al Lung sequestration: report of seven cases and review of 540 published cases Thorax 1979;34:96–101.

29 Nutchtern JG, Harberg FJ Congenital lung cysts Semin Pediatr Surg 1994;3:233–43.

Management of Pulmonary Arteriovenous Malformations and Sequestrations / 239

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30 Silverman ME, White CS, Ziskind AA Pulmonary

seques-tration: retrieving arterial supply from the left circumflex

coronary artery Chest 1994;106:948–9.

31 Buntain WL, Woolley MM, Manhour GH, et al Pulmonary

sequestration in children: a twenty-five year experience.

Surgery 1977;81:413.

32 John PR, Beesley SW, Mayne V Pulmonary sequestration

and related congenital disorders A clinicoradiological

review of 41 cases Pediatr Radiol 1989;20:4.

33 Collin P-P, Desjardins JG, Khan AH Pulmonary

sequestra-tion J Pediatr Surg 1987;22:750.

34 Rubin EM, Garcia H, Horowitz MD, Guerra JJ Jr Fatal

massive hemoptysis secondary to intralobar sequestration.

Chest 1994;106:954.

35 Eisenberg P, Cohen HL, Coren C Color doppler in

pulmonary sequestration diagnosis J Ultrasound Med

38 Adzik NS Fetal thoracic lesions Semin Pediatr Surg 1993;2:103–8.

39 Dolkart LA, Reimers FT, Helmuth WV, et al Antenatal diagnosis of pulmonary sequestration: a review Obstet Gynecol Surv 1992;47:515.

40 Becmeur F, Horta-Geraud P, Donato L, Sauvage P Pulmonary sequestrations: prenatal ultrasound diagnosis, treatment, and outcome J Pediatr Surg 1998;33:492.

Hydatid disease, which is caused by the tapeworm

Echinococcus granulosus or Echinococcus multilocularis, is

known as echinococcosis or hydatidosis Hydatid disease

is a severe helminthic zoonosis with major medical, social,

and economic impacts in countries in which it is seen

Echinococcosis is endemic in Australia, New Zealand,

South Africa, South America, the Middle East, Alaska, and

Canada, where it is widespread among aboriginal tribes.1,2

Hydatidosis or echinococcosis is certainly one of the

oldest human diseases Hippocrates referred to hydatid

disease in the aphorism, “When the liver is filled with water

and bursts into epiploon, the belly is filled with water and

the patient dies.” Galen, in the first century also made

reference to this disease Thebesius described hydatid

disease in the seventeenth century Finally Rudolphi (1808)

published a large treatise on the parasite, first using the

term “hydatid cyst” to describe echinococcosis in

humans.3,4The first report of hydatid cyst in humans in the

medical literature is attributed to Bremser in 1821.5

Hydatidosis is characterized by the development of

cysts as a consequence of the parasitization of humans by

the larva of Taenia echinococcus Although there are four

well-known species (E granulosus, E multilocularis,

Echinococcus oligarthus, Echinococcus vogelii), only E.

multilocularis and E granulosus are human pathogens.

The latter is the causative organism in most cases of

human infection E vogelii and E oligarthus may cause

polycystic echinococcosis very rarely.6

Parasite

The Echinococcus belongs to the phylum Platyhelminthes

and the family Taeniidae In its adult stage, the parasite

lives in the intestinal tract of carnivores Mature E

granu-losus is a little parasite, 2 to 7 mm in length, 0.6 mm in

width, and is composed of a scolex (head), neck, and 2 to

3 proglottids The head has four suckers and 30 to 40hooklets that serve to fix the parasite in the intestinal wall

of its definitive host, the dog or any other related canine.The first proglottid is not a well-defined segment; thesecond one contains the required equipment for sexualreproduction of this true hermaphrodite; and the third,also called the pregnant proglottid, contains the eggs,varying in number from 400 to 800 Average lifetime ofthe mature parasite in the dog’s intestines is 5 months.During this time period, after being eliminated with thefeces, the eggs keep contaminating fields, irrigated land,and wells After this segment is discharged, the anteriorbecomes pregnant for reproduction later on Thedetached eggs are 40 microns in size and highly resistant

to physical and chemical agents and survive in adverseconditions for several weeks or months (1 week in water,

4 months in ice, and 10 months in soil).7These eggs areintroduced into intermediate hosts either by directcontact with dogs or ingestion of contaminated grass,water, vegetables, and such In the duodenum or in theupper part of the jejunum of the intermediate host,however, the chitinous embryophore that covers the eggs

is ruptured by the action of digestive enzymes The larvalstage, which cannot occur in the main host, begins in theintermediate host and leads to the development ofhydatid disease within the viscera of these animals Thecycle is completed with the ingestion of the infectedviscera by carnivores (primary host), and thus the cyclecontinues

Following the rupture of the egg, the hexacanthembryo, with aid of its hooklets, attaches to and pene-trates the mucosa of the duodenum and jejunum, enters

the mesenteric venules, and proceeds to the portal vein.

Reaching the tributary veins of the liver, this embryo can

be retained by the sinusoidal capillaries of the liver, or if

they escape they may become lodged in the lung, where

they would also be transformed into hydatids Rarely

embryos can bypass the pulmonary barriers through

precapillary anastomoses They are responsible for the

sporadic cases of extrapulmonary and extrahepatic

hydatidosis The incidence of hepatic involvement in

echinococcosis is 50 to 80%.7,8

The lungs are the secondmost common site of lodgment of the parasite, with an

incidence varying between 10 to 30%.3,7,8If the hexacanth

embryo manages to get past the pulmonary filter, it

reaches the left heart and, by way of the aorta, the

remainder of the organism, mainly the kidney, spleen,

and bones in the remaining 10% It has been shown that

the embryos can reach the lung via the lymphatic vessels,

bypassing the liver The embryo may enter the lymphatics

of the small intestine, proceeds to the thoracic duct, to

the internal jugular vein, to the right side of the heart,

then to the lungs Although some researchers have

supported the possibility of direct pulmonary exposure

through the inhalation of air contaminated with

Echinococcus, it is doubtful whether the bronchial

secre-tions can lyse the embryophore of the hexacanth to

liber-ate the embryo.9After capillary embolization, many

embryos are destroyed by phagocytosis, but some reach

the larval stage of the echinococcus—the hydatid cyst

Although pulmonary cysts may establish in every lobe

of the lungs, they are more frequent in lower lobes and

mainly in the right hemithorax.1,8,10–12In children, the

presence of hydatid disease in the lungs has been

reported to be up to 67%,13–15whereas in adults cysts are

more prominent in the liver

Pathology

Hexacanth embryo loses its scolex at the organ in which

it lodges, transforms into a cyst, and starts growing

Following the inflammatory reaction in the first few days,

hydatic vesicula forms by the end of the first week At the

end of the 10th day, germinative membrane starts to

mature and starts to be covered by cuticula By day 90 a

cyst of 4 to 5 mm with all layers complete is formed

Doubling time of the cyst is approximately 16 to 20

weeks, but the factors effecting this doubling time are

unknown Their diameter can increase, from a few

millimeters up to approximately 5 cm in 1 year.16

The hydatid cyst is formed by two components: (1)

the adventitia and (2) the parasite itself (Figure 19-1)

1 Adventitia (host reactional layer; pericyst): With the

host attempting to isolate the parasite from the rest

of the adjacent structures, this membrane, the

adventitia (pericyst), is formed by thick connectivetissue and in part by parenchymal tissue collapsed

b Endocyst (germinative membrane): The cellularmass is formed in this layer It is a thin transparentmembrane that is lined with small papillae, whichare brood capsules at different stages of develop-ment The germinative membrane is the livingpart of the parasite and produces the laminatedmembrane and reproduces the parasite(Figure 19-2)

The daughter cysts are produced from the germinalmembrane These cysts contain 10 to 60 heads of babyscolices, which are called protoscolex These cysts oftendetach from the vesicle’s inner wall and float in the fluidtogether with the protoscolices from the ruptured ordead daughter cysts, which constitute the so-calledhydatid sand

242 / Advanced Therapy in Thoracic Surgery

FIGURE 19-1 The hydatid cyst and its components.

implantations When the hydatid cyst ruptures into the

pleura it causes a hydatid hydropneumothorax When a

bronchoadventitial–pleural fistula is also present,

secondary infection of the cavity will produce a hydatid

pyopneumothorax, and this may be manifested by severe

chest pain, dyspnea, dry cough, generalized malaise, and

fever In some patients, intense chest pain, persistent

cough, and severe dyspnea and even cyanosis, shock, and

suffocation may be observed Allergic reactions to all

degrees and even death can occur

Suppuration of the cyst can occur after rupture and

secondary infection Bacterial contamination from

bronchial involvement can simulate a chronic lung

abscess, with or without the chitinous membrane

included in the purulent fluid General symptoms of a

chronic infection, fever, generalized malaise, and

hemop-tysis can occur in these patients

The diagnostic possibility of a ruptured hydatid cyst

with a retained membrane should always be considered

when the surgeon is confronted with a chronic abscessthat is unresponsive to usual therapy

The coexistence of hepatic and pulmonary lesionsshould always be suspected In 18 to 40% of pulmonaryhydatidosis there can be simultaneous involvement of theliver and lung.21,22 Hydatid cyst of the liver is mostlyasymptomatic In 60 to 85% of cases the cyst is localized

in the right lobe of the liver (Figure 19-3) Pain in theright upper quadrant of the abdomen, hepatomegaly,nausea, and vomiting are the clinical manifestations ofliver involvement When the cyst in the liver becomeslarger then 10 cm or ruptures, severe abdominal compli-cations like obstructive jaundice, cholangitis, and pancre-atitis may occur If the hepatic cyst perforates thediaphragm, hydatic contents of the cyst reach the pleuralspace, producing a hepatic thoracic transdiaphragmaticpleural hydatidosis This is often a dramatic clinical eventwith sudden and acute thoracic pain, cardiovascularcollapse sometimes leading to shock, and hydatid allergy(urticaria, bronchospasm, and fever) Hepatic thoracictransdiaphragmatic hydatidosis may present in an acutefashion, with epigastric pain, cough, fever, shortness ofbreath, biliphtisis, and anaphylactic reactions

Diagnosis

In clinical practice, plain radiographs of the chest havebeen shown to be most reliable in diagnosing pulmonaryhydatid disease Radiographically an intact cyst appears as

a round or oval shape, solitary or multiple, with neous density and perfectly defined margins (Figures 19-4and 9-5) Alteration from a spherical to an oval shape may

homoge-be observed during deep inhalation (the

Escudero-244 / Advanced Therapy in Thoracic Surgery

TABLE 19-1 Clinical Symptoms of Pulmonary Hydatid Cyst

Symptoms Direct effects of the cyst Cough, chest pain, hemoptysis, dyspnea

Rupture of the cyst Cough, vomit-like expectoration of germinative

membrane or scolices (hydatoptysis), hemoptysis, chest pain

Infection of the cyst Fever, hemoptysis, expectoration, weight loss

Allergic Reactions Lung Bronchospasm, dyspnea, pulmonary

congestion, eosinophilic infiltration Skin Pruritis, erythema, generalized urticaria,

angioneuropathic edema Cardiovascular Anaphylactic shock, tachycardia, sudden death

Abdominal Distention, cramps, diarrhea

Other Autoimmune myopathy

FIGURE 19-3 Computed tomography scan of liver showing a large

hepatic cyst in the right lobe with multiple vesiculation—a common

finding in hepatic hydatid disease.

FIGURE 19-4 Chest radiograph showing two peripheral hydatid cysts

in the left lung.

Magnetic resonance imaging is not being usedroutinely in the diagnosis of hydatid disease of the lung.

It may show detached membranes, daughter cysts, localhost reactions, or communications between the cyst andthe bronchial tree in ruptured cysts (Figure 19-11).Abdominal ultrasound or CT of the upper abdomenhas to be performed routinely to determine whether livercysts are present

Bronchoscopy was used in the diagnosis of pulmonaryhydatidosis prior to imaging techniques such as CT andmagnetic resonance imaging; its use has been limited bythe risk of rupture of the cyst and the subsequent devel-opment of severe complications It still may be useful incases of ruptured hydatid cyst of the lung because itenables the visualization and removal of cysticmembranes from the bronchial tree

When the initial chest radiograph leads to a suspicion

of hydatid disease, several clinical laboratory tests can becarried out, including the peripheral blood eosinophilcount, Casoni’s intradermal test, the Weinberg reactiontest, and the erythrocyte sedimentation rate Indirecthemagglutination test, latex agglutination, immunoelec-trophoresis, double-diffusion immunoelectrophoresis,total immunoglobulin E (IgE) or specific IgE, indirectimmunofluorescence, and enzyme-linked immunosor-bent assay (ELISA) are the serologic tests that are stillbeing used.29–31

Peripheral blood eosinophilia is neither specific norconstant because not all patients with hydatidosis presenteosinophilia and, on the other hand, eosinophilia canexist in patients with other parasites or allergic processes

246 / Advanced Therapy in Thoracic Surgery

FIGURE 19-8 Computed tomography scan of a patient presenting

with a pyothorax on the left side reveals a cyst floating in the pleural

effusion (wanderer cyst).

FIGURE 19-9 Computed tomography scan of a small, ruptured

hydatid cyst in the right upper lobe showing a collapsed echinococcal

membrane (water lily sign).

FIGURE 19-10 Computed tomography scan showing a giant hydatid

cyst in the right hemithorax filling the entire thoracic cavity.

FIGURE 19-11 Magnetic resonance imaging scan showing multiple

hydatid cysts in the left upper lobe with extrathoracic extension.

As eosinophilia occurs in 20 to 34% of the patients with

echinococcosis,32this test has little diagnostic value

The Casoni skin test consists of the intradermal

injec-tion of 0.2 to 0.3 mL of hydatid fluid from sheep cysts,

filtered and undiluted, into the anterior aspect of the

patient’s forearm, similar to the procedure used for the

tuberculin test The reaction is positive in 50 to 95% of

cases, but a negative result does not rule out the presence

of hydatid disease On the other hand, false-positive

reac-tions can occur in patients with other parasitic and

nonparasitic diseases As it lacks specificity, it is no longer

recommended

The Weinberg reaction test, also referred to as

comple-ment fixation test is based on the existence, in the plasma

of hydatid cyst carriers, of circulating reagins It is not a

specific test, and its sensitivity rate is reported to vary

from 36 to 93%.33

The indirect hemagglutination test was introduced in

1957 by Garabedian.34 Its sensitivity ranges from 66 to

100%, and false-positive results are 1 to 2% It has been

the clinical test of choice for the last four decades

Six serologic tests were compared by Zarzosa and

colleagues in 1999.35 IgG ELISA was found to have the

highest sensitivity (84%), followed by IgM ELISA (62%),

indirect hemagglutination test (61%), latex agglutination

(58%), immunoelectrophoresis (51%), and specific IgE

ELISA (44%) The specificity of all tests was found to be

98 to 100% False-positive results were seen in patients

who had parasitic diseases like Taenia saginata and

Taenia solium or nonparasitic disease like lymphoma and

leukemia IgG ELISA, with its very high sensitivity and

specificity rates, seems to be the serologic test of choice

for use in the clinic

Pulmonar y hydatid disease may mimic several

pulmonary diseases Some of the pulmonary diseases

that the surgeon must consider in the differential

diagno-sis of pulmonary hydatid disease are lung abscess,

pulmonary tuberculosis, bronchiectasis, lung cancer,

metastatic tumors, pneumonia, pleural effusions and

empyema, mesothelioma, pneumothorax, bronchial

cysts, pericardial cysts, benign neoplasms of the lung,

fungal infections, and diaphragmatic hernias

Treatment

Rarely hydatid cysts of the lung heal by spontaneous

rupture and evacuation into the bronchus, though

complications such as infection, abscess formation,

bron-chogenic spread, and anaphylactic shock may occur

Medical Treatment

The results of treatment of hydatid disease with

benzimi-dazole compounds during the last two decades have been

described Gil-Grande reported partial or complete clinicalresponses in 36 to 94% of the patients treated with meben-dazole.36Horton reported that albendazole therapy in

E granulosus infection can result in apparent cure in up to

30% of cases, with a further 40 to 50% showing objectiveevidence of response when followed in the short term.37

The effectiveness of these drugs is apparently dependent

on the thickness of the cyst wall; the drug has to passthrough it to reach the germinal layer of the cyst Youngpatients and those with small cysts that have thin wallsappear to benefit most from this medical therapy.38

According to recent World Health Organization lines, chemotherapy is the preferred treatment whensurgery is not available, when complete removal of the cyst

guide-is impossible, when cyst contents threaten to dguide-isseminatedue to cyst rupture, or when cysts are too numerous.21,39

Despite the benefits afforded by chemotherapy in themanagement of pulmonary hydatidosis, to date surgery isstill the treatment of choice based on results achievedand the low morbidity and mortality rates.8,40–46 Thedifferent surgical techniques available for pulmonaryhydatid cystic disease can be divided into two types:those involving conservation and those involvingremoval of lung parenchyma

Surgical Treatment

Historically, the surgical management of hydatid diseasehas passed through different stages In 1899 Posadasadvised only suturing of the bronchial openings As thismethod did not prevent air leaks, fixation of the edges ofthe sutured pericystic zone to the thoracotomy incision waslater added Incising the lung parenchyma and removingthe cyst (simple enucleation) was reported by Ugon andcolleagues in 1946.47Barret in 1947 described removal ofparasite and obliteration of the remaining cavity with aseries of purse-string sutures (enucleation and capiton-nage).48Allende and Langer in 1947 supplemented capiton-nage with suturing of the individual bronchial openingswithin the cavity.49Pérez-Fontana in 1951 described a newmethod known as pericystectomy (capsule resection).50Allthese techniques are conservative methods

The technical difficulty with Pérez-Fontana’s method(pericystectomy) is the creation of an appropriate planethrough the pulmonary tissue, near and around the para-sitic cyst, with the resulting bleeding and air leak Afterresection of the pericyst the remaining cavity may bedifficult to obliterate

The choice of surgical technique depends on theconditions encountered during surgery Regardless thesurgical methods adopted, removal of the entire parasite,prevention of its dissemination, maximal preservation ofpulmonary function, and the immediate obliteration ofthe remaining cavity are the basis for effective therapy

Management of Hydatid Cysts / 247

Removing unilateral multiple cysts is not difficult.

Bilateral lung cysts can be operated in one- or two-staged

thoracotomies depending upon the condition of the

patient In a patient with bilateral hydatid disease the side

with the larger cyst should be operated first If the patient

has bilateral disease with complicated cyst in one lung,

the noncomplicated cyst should be removed first to

prevent its future rupture The lesions in the other lung

can be operated on in the same session or 2 to 4 weeks

after the first operation (Figure 19-12)

Several surgeons have used a median sternotomy for

bilateral lesions.42It carries less morbidity than the bilateral

standard posterolateral thoracotomy, but the sternotomy

approach can pose a technical challenge, especially when

the cysts are localized in the dorsal pulmonary segments

and if a major resection of the lung tissue is indicated

Surgical Technique

A posterolateral thoracotomy in the fifth or sixth

inter-costal space is accomplished with the patient under

conventional general anesthesia and in the lateral

decubi-tus position All patients are intubated with a

double-lumen endotracheal tube to prevent contralateral

aspiration of blood and other secretions If accidental

rupture of the cyst occurs during anesthesia or surgery,

contralateral aspiration of the cyst fluid and bronchial

dissemination can be seen

After the cyst is identified, the surgical wound and

adja-cent lung tissue are covered with normal saline or 1%

(vol/vol) povidone–iodine-impregnated gauzes to prevent

seeding of possible daughter cysts The cystic mass is

usually seen as a soft, elastic, yellowish-white swelling on

the surface of the pulmonary parenchyma The pericystic

membrane is opened by a short incision that surrounds

the most superficial part of the cyst in the visceral pleura.Excision of the intact hydatid cyst is accomplished by care-ful separation of the laminated membrane from the peri-cystic zone The cyst is pushed out of its chamber with theaid of high-pressure ventilation provided by manual infla-tion of the corresponding arm of the double lumen tube.The laminated membrane should never be grasped with

an instrument, before or during the delivery of the cyst.Delivery of the cyst can be carefully assisted with fingersonly, to avoid cyst rupture (Figure 19-13A and B)

Although the best method is the enucleation andobliteration of the residual cavity, as most of the cystseither are very large or very tense or localized deep in thelung parenchyma it is nearly impossible to enucleate thecyst In such cases we prefer to aspirate the cyst contentswith a needle and open the cavity with the cautery As it

is nearly impossible to protect the lung from spilled

248 / Advanced Therapy in Thoracic Surgery

FIGURE 19-12 Multiple echinococcal cysts removed from the lung

and pleura of the patient in Figure 19-8.

FIGURE 19-13 A, Dissection of the hydatid cyst The pericystic

membrane is opened and the parasite can be seen B, Enucleation nearly

completed Note the Allis clamps hold the pericystic membrane only.