the natural and “unnatural” history of congenitally corrected transposition

The Natural and WnnaturaP History of Congenitally Corrected Transposition

Ulla Lundstrom, MD, Catherine Bull, MRCP, Richard K.H. Wyse, PhD, and Jane Somerville, FRCP

The data available on 111 patients with congenltal- ly conwted transpositton and 2 adequate ventricles managed over the 200year period to 1999 were reviewed retrospectively. The ages of survl- vors ranged from 1 to 99 years (median 26) and all but 10 had additional anatomic abnormalitles. Tri- cuspld valve abnormalities were more prevalent in patients symptomatic with heart failure (26 of 43 patients) than those whose main problem was cyanosis (11 of 52 patii); all dysplastic or Ebsteln valves were at least moderately incompetent. hdra- cardiac repair of the lesion was attempted in 51 patients wlth 11 early deathq in multivariate mod- els, the risk factors for early death or a bad early outcome or poor result 6 months later related to poor preoperative symptomatic status (especially from heart fallure), impaired right ventricular function, heart block and younger age at surgery. Pa- tients wlth more than mild preoperative tricuspid regurgitation whose valves were not replaced did very poorly. Thus, patients symptomatic from heart failure should probably be repaired early in the natural history of the disease, before the systemic right ventricles dilate. By contrast, the course of patients who were predominantly cyanosed was more stable in early childhood and their surgical outcome was less compromised by poor preopera- tlve symptomatic status; thelr intracardiac repair can probably be delayed until symptoms become unacceptable.

(AmJCardiol1990;65:1222-1229)

From the Department of Pediatric Cardiology, Institute of Child Health, the Hospital for Sick Children, and the National Heart Hospi- tal, London, England. Dr. Lundstrom was supported in part by the British Heart Foundation, London. Manuscript received October 3, 1989; revised manuscript received January 12, 1990, and accepted January 16.

Dr. Lundstrom’s present address: Children’s Hospital, Helsinki, Finland.

Address for reprints: Catherine Bull, MRCP, Hospital for Sick Children, Great Ormond Street, London, England WClN 3JH.

C ongenitally corrected transposition is an example of a cardiac defect in which differences in no- menclature can become a source of serious mis-

understanding.’ The essence of “corrected transposition” is the combination of atrioventricular and ventric- uloarterial discordance. Ventricles and atrioventricular valves are named according to their morphology; thus, in this condition the right ventricle is the systemic ventricle and the tricuspid valve is the systemic or “left” atrioventricular valve (Figure 1).

The strategies for the surgical management of patients with corrected transposition may differ from those of patients with normal connections and the same hemodynamics2 There are several reasons for this: the complications of heart block,3 systemic ventricular dysfunction and progressive incompetence of the systemic atrioventricular valve occur spontaneously as the years advance but unfortunately can also be induced or exac- erbated by surgerya Intracardiac repair may demand insertion of conduits, prosthetic valves, or both, so that such surgery is often delayed until an older age; thus, palliative extracardiac operations still have an important role. Finally, management choices are made more difficult because the condition is rare and our concep- tions of the natural and unnatural history rely on sparse studies.2,5,6

With the advantage of patients from 2 units dealing with congenital cardiac defects from the cradle to the grave, we set out to review our experience with corrected transposition, hoping particularly to help clinicians with 4 clinical dilemmas. (1) Are patients with cyanosis better served by a shunt or by intracardiac repair? (2) How should an abnormal systemic atrioventricular valve be managed during an intracardiac repair of other defects? (3) Should asymptomatic or barely symptomatic patients be operated on? (4) Is there a subset of patients in whom the risk of conventional surgery is un- acceptably high, so that the patient may be better served by cardiac transplantation?

METHODS This study is a retrospective review of 111 patients

with congenitally corrected transposition and 2 ventricles of adequate size followed either at the Hospital for Sick Children or at the National Heart Hospital, Lon- don, or both, during the 20 years to 1988. For the pur- poses of this study we also included patients with double outlet right ventricle or pulmonary atresia in the setting of atrioventricular discordance. We included all patients meeting the above criteria whose records were available.

1222 THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 65

We reviewed all available angiographic, echocardio- graphic, operation and postmortem reports.

Natural and “unnatural” history: Based on clinical information from visits, each patient was given an “ability index” from 1 to 47 every 5 years as well as before and 6 months after each operation. Postoperatively, ability index 4 implied extreme limitation or the need for reoperation within 6 months.

Although the patients all met morphologic selection criteria, their clinical course and management also de- pended on physiologic patterns. Thus, we distinguished patients in 3 broadly different categories: those who were asymptomatic on presentation, those who were cyanosed, however trivially, or those who were in heart failure, however mildly. The course of these groups before intracardiac repair, their perioperative mortality and postoperative survival are summarized.

To establish the “natural history” of the well patient, we prepared actuarial curves to show survival of patients within ability index 1 or 2 without intracardiac repair, but sometimes with palliative extracardiac ma- neuvers. Patients were “withdrawn alive” when last seen or at the time of intracardiac surgery if undergoing elective intracardiac repair from this relatively well status. Patients were “withdrawn dead” at death or when they fell into ability index 3 or 4. Curves were curtailed when they reflected data from <5 patients.

The outcome of surgery was considered “bad” if the patient died within 1 month of surgery or if a second operation was required within 6 months or if the patient had an ability index of 3 or 4 at 6 months after operation.

TRICUSPID VALVE: The tricuspid valve was defined as “dysplastic” if the leaflets were thick and abnormal with or without shortened chordae, when observed on cross-sectional echocardiography, surgery or autopsy. It was considered “Ebstein” if there was additional down- ward displacement of the septal and mural leaflets at echocardiography, surgery or autopsy.8

The competence of the tricuspid valve was assessed by right ventricular angiography. (All patients had undergone right ventricular angiography before intracardiac surgery, though only 35 of 51 angiograms were still available for review; in an additional 5 patients there was a reliable report on the tricuspid valve regurgitation.) Tricuspid regurgitation was considered trivial (I /4) if the dye cleared with each beat and never filled the entire left atrium, mild (2/4) if it opacified the entire left atrium faintly after several beats, moderate (3/4) if the left atrium was completely opacified and achieved equal opacification with the right ventricle and severe (4/4) if opacification of the entire left atrium occurred with 1 beat and became more dense with each beat and there was reflux of contrast into the pulmonary veins.9 Function of the right ventricle was judged from angiography and graded good, moderate or bad.

RISK FACTOR ANALYSIS: Using multivariate analysis, we examined the impact of physiology, symptoms, previous palliation, preoperative or surgical heart block, morphology and competence of the tricuspid valve and function of the right ventricle on the outcome with and

TABLE I Variables Examined in Risk Factor Analysis

Age at operation Date of operatron Prevrous pallration Abrlrty Index preoperatively (l-4)

(1.2-3,4) Preoperative heart block Surgrcal heart block Any heart block TV morphology (normal vs dysplastrc. straddlrng. Ebstern) TVregurgrtatron (O-1/4vs2-4/4) TV status (normal and competent vs dysplastic or normal but

regurgitant Z-4/4) Morphologrc RVfunction (good, moderate, bad)

(good vs moderate or bad) Heart farlure hemodynamrcs

RV = right ventricular; TV = trwspld valve.

without intracardiac repair. Risk factors examined are listed in Table I.

The date of the first electrocardiogram with complete heart block present was considered the date of es- tablishment of the heart block. If heart block occurred first within 30 days of surgery, it was considered to have been induced by surgery.

RESULTS Review: ANATOMY: All but 10 patients had associ-

ated anomalies (Table II). STATUS: Of the 111 presenting, 26 patients had died

by 1988. Patients were then at various stages in the natural and unnatural history of their condition (Figure 2). The survivors ranged from 1 to 58 years of age (median 20 years) in 1988.

FIGURE 1. ComgedtaUy cowredd transposition. Ao = aorta; LA=leftatrium;LV=kRventricle;PA=puLnonaryartery; RA = righl atrium; RV = right ventrick.

THE AMERICAN JOURNAL OF CARDIOLOGY MAY 15. 1990 1223

TABLE II Associated Cardiovascular Anomalies

None 10 Ventricular septal defect 90 Pulmonary stenosis 80

Valvular 57 Subvalvular 47 Atresia 7

Tricuspid valve abnormality 37 Ebstein 18 Dysplastic 9 Straddling 10

Atrial septal defect 12 Double outlet right ventricle 12 Criss-cross arrangement 3 Coarctation of the aorta 4 Subaortic stenosis 1 Atrioventricular septal defect 1 Total anomalous pulmonary venous drainage 1 Partial anomalous pulmonary venous drainage 1 Persistent ductus arteriosus 1

PHYsIoLocY: Sixteen patients were asymptomatic on presentation, 52 were cyanosed and 43 were in heart failure (Figure 3). The 52 patients who were cyanosed at presentation all had a ventricular septal defect and pulmonary stenosis with a right-to-left shunt at the ventricular level. The 43 patients with heart failure either had a left-to-right shunt through a ventricular septal de-

fect or an abnormal tricuspid valve, or both. Ventricular septal defect was rarely isolated, often being associated with mild subpulmonary stenosis. In the asymptomatic group, 10 had no associated lesion and 6 had pulmonary stenosis, 1 with an additional persistent ductus arteriosus.

TRICUSPID REGURGITATION: The prevalence of tricuspid valve anomalies was not uniform within these physiologic groups. The tricuspid valve was considered abnormal in 37 patients, straddling in 10, dysplastic in 9 and Ebstein in 18 patients. Where data were available, the normal valves were competent or only trivially incompetent in 83%, mildly regurgitant in 13% and, at the most, moderately regurgitant in 1 patient who had severe right ventricular dysfunction. All dysplastic or Ebstein valves were at least mildly regurgitant (2/4) and more often moderately or severely regurgitant preoperatively.

When the preoperative right ventricular dysfunction was moderate or severe, the tricuspid valve was competent in only 2 of 9 cases, and the remainder had at least moderate incompetence.

Course before intracardiac repair: Sixteen patients are unlikely ever to need intracardiac surgery by virtue of trivial or absent associated lesions. Most of a further 23 are as yet unoperated but will probably require repair. Of this group for whom future surgery was con-

die

n definitive repair

w palliated

0 awaiting operation

H thought inoperable

pJ no need for surgery

,2 6o 3 $$# 50 ‘i; B 40

30

TV abnm-ml 20

ASYMPTOMATIC CYANOSIS HEARTFAILURE

no lesion (10) VSD+PS (52) VSD(14) TV abnomul

PS (6) VSD+mild OdY (5) PS(24)

FlGURE2.Statusofthe 111 patienbat review in January 1999.

FIGURE 3. Patients gmuped according to physiology. Ps = puhnonary stsnosls; TV =t&uspidvalve;VSD=vantricuhrseptal defect.


templated, 3 died in early childhood, 1 suddenly and 2 of infection.

The range and mortality of the extracardiac operations are listed in Table III. The survival within ability index 1 or 2 without intracardiac repair is shown in Fig- ure 4. At the age of 5 years, 90% of the cyanotic group were still within ability index 1 to 2, either unoperated or having had only a shunt. Tricuspid valve problems accounted for a few patients becoming symptomatic under 2 years of age. Patients with heart failure generally became more symptomatic earlier, especially if there was a tricuspid valve problem. If there was a tricuspid valve abnormality or incompetence at the time of diag- nosis, the percentage of patients within index 3 or 4 was already 18% during infancy and 30% by 5 years.

OLDER UNREPAIRED PATIENTS: Twenty-two patients followed currently are over the age of 20, 2 palliated with shunts and 20 without any surgery other than pacing. All are in ability index 1 or 2. Three women became pregnant; all were in their twenties with the combination of ventricular septal defect and pulmonary stenosis but uncorrected. Four healthy babies were born uneventfully and there was 1 first trimester miscarriage.

Intracardiac repair: Fifty-one patients have undergone intracardiac repair to date (Table IV).

RISK FACTOR ANALYSIS: The influence of preoperative ability index on early postoperative mortality is shown in Figure 5 for patients in the 3 physiologic groups. Pa- tients who were very symptomatic from heart failure had a poor outlook, only 2 of 11 having a good result 6 months after surgery. Preoperative symptomatic status had less influence on outcome in the cyanotic patients.

Multivariate analysis of risk factors for early death, poor early postoperative result or bad result at 6 months is listed in Table V, which underlines the risks to the very symptomatic patient with heart failure.

MANAGEMENTOFTHETRICUSPIDVALVE IN FIRSTINTRA- CARDIAC REPAIR: In 44 of 51 patients undergoing intracardiac repair, adequate estimates of preoperative tricuspid valve competence were available (Figure 6).

TABLE III Extracardiac Operations

Repair coarctation Ligation persistent ductus Banding of pulmonary artery First systemic-pulmonary

shunt Second shunt

No.

2 1 7

30

6

Early Mortality %

0 0

14 0

0

Three types of tricuspid valves were not replaced. (1) Competent or trivially incompetent tricuspid

valves-the valve was preoperatively competent or only trivially regurgitant in 25 patients; all the valves in this group were of normal morphology. A bad surgical outcome was seen in 5 patients. One died 6 days after operation because of sepsis related to a pacemaker. The other 4 had bad right ventricular function after operation, 3 dying of heart failure. However, the tricuspid valve is known to have remained competent in 3 and was only mildly regurgitant in 1 during the early postoperative course. Three had been thought to have good ventricular function preoperatively.

(2) Mildly regurgitant tricuspid valves-7 patients with mild (2/4) preoperative regurgitation of the tricuspid valve did not have the valve replaced in the first intracardiac operation. Their outcome was significantly worse than for the group with trivial or no regurgitation (p KO.001) as only 1 patient was in ability index 1 to 2 after the operation. Four others died 1 day, 5 days, 5 days and 4 years after operation, respectively, in heart failure with severe tricuspid valve incompetence; a further patient had the tricuspid valve replaced in a second operation.

(3) Moderately regurgitant tricuspid valves- 1 patient with moderate preoperative tricuspid valve regurgitation (grade 3/4) did not have primary valve replacement; he required replacement of the valve 3 months

60 1

THE AMERICAN JOURNAL OF CARDIOLOGY MAY 15, 1990 1225

TABLE IV First Intracardiac Operations

%

Early No. Mortality

VSD closure alone 6 50 VSD + TV replacement 4 25

or reconstruction TV replacement or 5 20

reconstruction VSD + LV-PA conduit 23 22 VW + pulmonary valvotomy 6 17 VSD + subpulmonary 2 0

resection VSD + TV replacement + 1 0

pulmonary valvotomy VSD + LV-PA conduit + 1 0

TV replacement Subpulmonary resection only 1 0 Pulmonary valvotomy only 1 0 LV-PA conduit only 1 0

LV = left ventricle; PA = pulmonary artery; N = tricuspid valve; VSD = ventricular septal defect.

later because of increasing heart failure and severe regurgitation.

The tricuspid valve was replaced (9) or reconstruct- ed (2) in 11 patients altogether. One of these valves was morphologically normal, 2 were dysplastic and 8 were Ebstein. Seven patients survived.

Heart block: Heart block has been observed in 35 of 111 patients to date; 14 were related to surgery. Sponta- neous heart block was documented in 21 patients; it was first noted at birth in 4, later in infancy in a further 2 and before the age of 10 years in all but 1 other who presented at the age of 37 years but had never been seen in sinus rhythm. Of the 15 who have not undergone intracardiac repair, 3 are paced. Of the 6 who have had intracardiac surgery, 2 were paced preoperatively and all postoperatively.

After intracardiac repair: Actuarial survival within ability index 1 to 2 without reoperation for patients who had preoperative ability indexes 1 to 2 and 3 to 4 are contrasted for both the cyanosed and heart failure groups (Figure 7).

Reoperations are listed in Table VI.

DISCUSSION Although a physiologically diverse group, patients

with congenitally corrected transposition have in common the anatomic rarity of atrioventricular and ventric- uloarterial discordance with a right ventricle and tricuspid valve supporting the systemic circulation.

As in other contexts, surgery may be indicated either because of unacceptable symptoms or as an investment for the patient’s future. Consideration of postoperative survival is unacceptable as sole criterion for decision- making; data relating to quality of life are important.

Cyanosed patkmtr: All our patients in this group had the combination of ventricular septal defect and pulmonary stenosis or atresia with “Fallot hemodynam- its”; such patients can usually be palliated with a systemic-to-pulmonary shunt (no perioperative mortality) or by an intracardiac repair, a higher-risk operation that often requires insertion of a conduit. Review of our data suggests that, at least for the first 10 years of life, most patients can be kept reasonably well-in ability index 1 or 2-if managed conservatively or with only a systemic-pulmonary shunt (19 of 29 patients undergoing intracardiac repair had required at least 1 previous shunt). Compared to tetralogy of Fallot, the absence of progressive infundibular obstruction in the corrected transposition settinglo may account for the fairly stable long- term course of the patients. It is possible that this well- being could have been maintained longer, but evidence is difficult to produce in the face of our inclination to attempt repair as symptoms gradually progress in the

HEART FAILURE CYANOSIS

PRECP ABILITY PREW ABILITY ABILITY 6M POSTOP ABILITY 6M POSTCP

PS ONLY

PRECP ABILITY ABILITY 6M POSTOP

El El

q D n-3

FIGURE 5. Gutcoma 6 months afhr intra- cardiacrepairrelatedtopreoperative (PREOP) abwty index. Postoperative (PO6TOP) ability index 4 Indudes aY pa- tlentswhorequlrodasscondopsnhsart prod1m~6monthrofthe6rst. M=monthqPS= PulmoMly stonosI8.


older patients. Poor preoperative symptomatic status (index 3 or 4) of these patients did not appear to prejudice immediate mortality, the status 6 months after operation or late survival within index 1 or 2. The implication for management must be that the increase in the patient’s symptoms can be allowed to determine the timing of operation.

Heart failure patients: These patients could have a ventricular septal defect, an intrinsically abnormal tricuspid valve, or both, and several had an element of

pulmonary valve stenosis, insufficient to produce right- to-left shunting. In common they have a volume over- loaded systemic right ventricle. The proportion of acyanotic patients who are well without intracardiac repair at 10 years was comparable to the cyanosed group, though in most of the acyanotic patients this was because of inherently “well-balanced” hemodynamics, rather than palliative surgery. In contrast to the cyanosed group, however, poor preoperative symptomatic status seemed to prejudice perioperative mortality, sta-

FIGURE 6.6ur&al management of the tricuspid valve. outcome of intracardiac repair related to sev~ of preoperative

FIGURE 7. Actuarial swvival within ability indexlor2afterttrstibacadh~ir, dated to wative ability index.

patients

TR O-114 TR 214 TR 3/4 TV replaced

0 good outcome

q bad outcome = death

or TV replacement within

or post op ability index 3

6 months

or 4

60 -

40 Q Ability 1,2

- + Ability 3,4

Acyanotic group

Q Ability 1 ,2 + Ability 3,4

0 1 2 3 4 5 years


TABLE V Multivariate Analysis of Risk Factors

P Value

For early death (51 patients, p <0.005 for model) Preoperative heart block Younger age at surgery

For bad early outcome (p <0.0005 for model) Moderate or bad right ventricular

function preoperatively Preoperative heart block Heart failure hemodynamics

For bad result at six months (p <O.C05 for model) Preoperative ability index Heart failure hemodynamics

<0.02 <0.05

<0.005

<o.ooo5 <o.ooz

<0.02 -co.05

TABLE VI Second Intracardiac Operations

No.

First TV replacement 2 Second TV replacement 2 First replacement of LV-PA conduit 3 Second TV replacement + conduit replacement 1 TV replacement + reclosure of VSD 1 VSD + LV-PA conduit 2 Heart and lung transplant 1

LV = left ventricle; PA = pulmonary artery; TV = tricuspid valve; VSD = ventricular septal defect.

tus at 6 months and late survival within ability index 1 or 2. The implication for the physician must be that the patients must not be allowed to deteriorate too much before repair is contemplated.

Thus, as a group, our patients with heart failure hemodynamics fared much worse than the cyanosed patients at intracardiac repair and a strategy for avoiding the disappointing results must be considered.

Operative de&ions: VENTRICULAR SEPTAL DEFECT CLOSURE OR BANDING? Heart failure demanding surgery in infancy has been uncommon in our experience (9 of 111 patients). Three infants died before operation and 6 were banded. Banding rather than intracardiac repair can often be justified in this context because the techni- cal difficulties of closing the often inaccessible ventricular septal defect while avoiding the conduction system are exaggerated in a small heart. Moreover, the “banded ventricle” is a left ventricle that can be expected to tolerate the pressure load wel1.l 1 It may be justifiable to recommend banding rather than accepting a barely thriving patient with a moderately elevated pulmonary artery pressure or large shunt-a situation that might be supervised conservatively in ventricular septal defect with normal connections.

MANAGEMENTOFTHEABNORMALORINCOMPETENTTRI- CUSPID VALVE: Serious deterioration in tricuspid valve competence early postoperatively has been noted in other surgical reviews.6 Competence of either atrioventricular valve depends on the structural integrity of the leaflets and on the diameter of the valve anulus. In the context of corrected transposition, the tricuspid valve may be intrinsically abnormal (as in one-third of the overall group) or the valve ring may be dilated due to ventricular volume overload (e.g., related to a ventricular septal


defect) or to myocardial dysfunction. Increasing valvar regurgitation causing increasing volume overload, anular dilatation and further regurgitation constitutes a vicious circle of dysfunction, more exaggerated if the systemic atrioventricular valve is morphologically tricuspid, as in this context. The degree of ventricular dysfunction seen early after cardiopulmonary bypass may be sufficient to exacerbate tricuspid regurgitation that had been tolerable preoperatively. Five of 7 patients with tricuspid regurgitation graded mild preoperatively (grade 2/4), and in whom the valve was un- touched in the initial repair, fared very poorly because of severe postoperative tricuspid regurgitation that caused the patients’ deaths in 4. The alternative strategy of electively replacing incompetent tricuspid valves was relatively well tolerated, with 7 of 11 patients surviving surgery. In our series, all dysplastic or Ebstein valves were at least mildly regurgitant (grade 2/4); only ex- ceptionally is the valve amenable to repair. Thus, tricuspid valve replacement as part of the intracardiac operation should be seriously considered, even if the valve competence seems “good enough” in the preoperative hemodynamic context.

TIMING OF INTERVENTION: Risk factors for death at intracardiac repair, for poor ability index at 6 months and for a poor late result include preoperative heart block (whether paced or not), younger age at operation, poor right ventricular function and “heart failure hemodynamics.” These features have in common an association with a dilated systemic ventricle. Their poor outcome may relate to the same vicious circle of tricuspid regurgitation associated with anular dilatation postulated to account for postoperative morbidity and mortality in patients with mild preoperative tricuspid regurgitation. If this is the case, management strategies for patients with congenitally corrected transposition must focus on maintenance of a small systemic ventricle-by early pacing of patients with heart block, by avoiding too large a systemic-pulmonary shunt when palliating young cyanotic patients and especially by early surgery in patients with a significant left-to-right shunt through a ventricular septal defect or important tricuspid regurgitation.

Clinical dilemmas: (1) Patients troubled by cyanosis can often be offered either a shunt or intracardiac repair. Because their perioperative mortality or longer- term outlook does not seem to be prejudiced by severe symptoms, intracardiac surgery can probably be delayed until symptoms become unacceptable. We do not have data to help the clinician facing the dilemma of complete repair versus palliative shunt. (2) Tricuspid valves that are mildly or more incompetent (grade 2/4 or worse) should probably be electively replaced during the course of an intracardiac repair. This will include all valves that are thought to be dysplastic or Ebstein. (3) Serious consideration should be given to operating on asymptomatic or barely symptomatic patients with a large heart due to dilatation of the systemic right ventricle related to a ventricular septal defect, tricuspid regurgitation, or both. These patients should fare better if operated on early in the natural history of their disease.

(4) Patients with heart failure and an ability index of 3 or 4 preoperatively do very badly; only 2 of 11 of our patients had a good early postoperative result and the survivors fared poorly later. Some of these patients may be better served by a cardiac transplant.

Acknowledgment: We appreciate the help of Sue Stone and Cynthia Payne, who assisted with data management.

REFERENCES 1. Macartney FJ, Shinebourne EA. Anderson RH. Connexions, relations, discordance and distortions. Br Heart J 1976:38:323-326. 2. Danielson GK. Atrioventricular discordance. In: Stark J, de Leval MR, eds. Surgery for Congenital Heart Defects. London Grunt and Stratton, /983;387- 396. 3. Daliento L, Corrado D, Buja G, John N, Nara A, Thiene G. Rhythm and conduction disturbances in isolated congenitally corrected transposition of the great arteries. Am J Cardiol 1986;58:314-318.

4. de Leval MR. Bastes P, Stark J, Taylor JFN, Macartney FJ, Anderson RH. Surgical technique to reduce the risks of heart block following closure of ventricular septal defect in atrioventricular discordance. J Thorac Cardiouasc Surg 1979;78:515-526. 5. Schiebler GL, Edwards JE, Burchell HB, Dushane JW, Ongley PA, Wood EH. Congenital corrected transposition of the great vessels, a study of 33 cases. fediat- rics 1961;27:(suppl I&849-888. 6. Fox LS, Kirklin JW, Pacific0 AD, Waldo AL, Bargeron LM. Intracardiac repair of cardiac malformations with atrioventricular discordance. Circularion 1976;54:123-127. 7. Warnes CA, Somerville J. Tricuspid atresia in adolescents and adults: current state and late complications. Br Heart J 1986;56:535-543. 6. Anderson KR, Danielson GK, McGoon DC, Lie JT. Ebstein’s anomaly of the left-sided tricuspid valve: the pathologic anatomy of the valvular malformation. Circulation 1978;57-58:(suppI 11):87-91, 9. Grossman W. Profiles in Valvular Disease. In: Grossman W, ed. Cardiac Catheterization and Angiography. Philadelphia: Lea and Febiger, 1986;359-381. 10. Anderson RH, Becker AE, Gerlis LM. The pulmonary outflow tract in classically corrected transposition. J Thorac Cardiouzsc Surg /975;69:747-757. 11. Mee RBB. Severe right ventricular failure after Mustard or Senning operation. Two stage repair: pulmonary artery banding and switch. J Thorac Cardio- “aw Surg 1986,92:385-390.


the natural and “unnatural” history of congenitally corrected transposition

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