The setting of discordant atrioventricular and ventriculoarterial connections, as seen in congenitally corrected transposition, allows for a normal circulation. Associated cardiac malformations, nonetheless, such as ventricular septal defect, obstruction of the pulmonary outflow tract, and abnormalities of the morphologically tricuspid valve, along with disturbances of atrioventricular conduction, occur in the majority of these patients.1–3 The management of such associated anomalies represents a major challenge of interdisciplinary treatment. There are two major surgical concepts to address the associated defects. Those using the classical repair aim at correcting the associated defects, while maintaining the morphologically right ventricle in the systemic circulation. Progressive dysfunction of the morphologically right ventricle, and tricuspid insufficiency, have been observed in a significant number of patients undergoing such classical repair.4–7 These findings have led to the alternative approach of restoring the morphologically left ventricle into the systemic circulation, by performing an atrial switch operation in addition to intraventricular rerouting, or in patients without left ventricular outflow tract obstruction, in addition to an arterial switch operation. Recent publications have demonstrated excellent hospital and intermediate-term survival.8–16 The presumed advantage of restoring the morphologically left ventricle into the systemic circulation in the intermediate- and long-term, however, remains to be demonstrated. The aim of our study is to provide follow-up data of 6 patients up to 17 years after anatomic repair of this rare combination of cardiac malformations.
Patients and methods
Morphologic features
The patients of our series presented with various abnormal segmental connections (Table 1). Between October 1988 and October 2003, 4 patients underwent an atrial switch operation concomitantly with a Rastelli operation, and 2 patients underwent an atrial switch operation and a patch-plasty of the pulmonary outflow tract for anatomic repair. So as to define the morphology, we followed the precepts as set out by Wilcox, Cook and Anderson.17
Table 1. Morphological features and surgical procedures in 4 patients (Patients 1 through 4) with usual atrial arrangement, and discordant atrioventricular connections, who underwent anatomic correction. The row for Patient 5 shows the morphological features and surgical procedures in the setting of isomerism of the left atrial appendages, who underwent anatomic correction, while the bottom row shows the features in the patient with mirror-imaged atrial arrangement.
Segmental connections
In 4 patients, there was usual arrangement of the atrial appendages (patients #1 to #4; Table 1). The fifth patient had isomerism of the left atrial appendage (Table 1). In this patient, the left-sided atrium was connected to the morphologically left ventricle and the right-sided atrium was connected to the morphologically right ventricle. In addition, the patient presented with interruption of the inferior caval vein, with azygos continuation to the left superior caval vein, draining the systemic venous blood to the left-sided atrium. The final patient had mirror imaged arrangement of the atrial appendages (patient #6; Table 1). All patients had discordant atrioventricular connections, except for the patient with isomerism of the left atrial appendage, who had mirror-imaged venous returns, but with ambiguous and biventricular atrioventricular connections in the setting of right handed ventricular topology. A criss-cross arrangement was seen in 1 patient. In terms of ventriculo-arterial connections, these were discordant in 2 patients, double outlet right ventricle in 3, and pulmonary atresia with origin of the aorta from the morphologically right ventricle in the final patient.
Associated cardiac malformations
All patients presented with an interventricular communication, which was perimembranous in 4, and subaortic with a muscular inferior rim in 2 patients. In 4 patients, there was an atrial septal defect within the oval fossa, whilst the fossa was probe-patent in the other 2 patients. As outlined above, 1 patient presented with pulmonary atresia, and 3 patients with pulmonary stenosis. In the 5 patients without pulmonary atresia, the aortic valve was placed to the left-hand side of pulmonary valve in 3, and to the right-hand side in 2 patients. The second patient presented with coarctation of the aorta.
Prior operations
In 4 patients with pulmonary outflow tract obstruction, a total of 6 systemic-to-pulmonary arterial shunt procedures had been performed, while the pulmonary trunk had been banded in 2 patients with unlimited pulmonary blood flow. In one of these, an additional atrial septectomy had been performed in order to improve the aortic saturation of oxygen. The other patient underwent repair of the aortic coarctation in addition to banding of the pulmonary trunk.
Haemodynamic details
All patients underwent cardiac catheterization prior to the anatomic correction, to assess ventricular function and pressures, and to delineate anatomy. Accordingly, left and right ventricular function was normal in all patients. The third patient presented with moderate tricuspid insufficiency, not related to an Ebstein-like malformation. The pressures in the left and right ventricles at the time of anatomic correction were almost equal in all patients, and ranged from 75 millimetres to 104 millimetres of mercury. The mean ratio of pressures between the morphologically left and right ventricles was 1.01 plus or minus 0.02, with a range from 0.99 to 1.04. The second patient presented with subvalvular aortic stenosis, and a pressure gradient of 11 millimetres of mercury between the morphologically left ventricle and the aorta. Pulmonary arterial pressure was below one third of the systemic pressure in all patients. The mean ratio of pressures between the pulmonary artery and the aorta was 0.22 plus or minus 0.05, with a range from 0.16 to 0.2. Mean systemic saturation of oxygen was 79.0 plus or minus 3.1%, with a range from 74 to 83%.
Indications for surgery
Indications for surgery were increasing cyanosis and limitation of physical activity in all patients. Anatomic correction was considered if the patients exhibited 2 morphologically normal ventricles, no straddling of the atrioventricular valves, normal function and systemic pressure of the morphologically left ventricle, in combination with low pressure in the pulmonary arteries.
Operative details
Mean age at the operation was 3.5 plus or minus 2.2 years, with a range from 1 to 6 years, and mean weight was 13.7 plus or minus 5.7 kilograms, with a range from 8 to 23 kilograms. The operation was performed with low-flow hypothermic, 20 at 24 degrees Celsius, cardiopulmonary bypass, using cold crystalloid cardioplegia for myocardial protection. Aprotinin was used in all patients. Mean cardiopulmonary bypass time was 252 plus or minus 63 minutes, with a range from 127 to 296 minutes, and mean aortic cross-clamp time was 153 plus or minus 34 minutes, with a range from 93 to 188 minutes.
Any previous shunts were ligated. The interventricular communication was closed in all patients through a ventriculotomy in the morphologically right ventricle, connecting the morphologically left ventricle to the aorta. In 3 patients we implanted a Dacron® patch, and in 3 patients a half-pipe shaped polytetrafluorethylene patch made from a longitudinally incised tube graft. Interrupted sutures were used in 1 patient, a running suture in 1, and a combination in the remaining 4 patients. The sutures were placed on the morphologically right ventricular side of the septum in order to avoid lesions to the conduction system. In 3 patients the interventricular communication was enlarged inferiorly in order to prevent obstruction of the outflow tract from the morphologically left ventricle to the aorta.
In 4 patients, we used the Senning procedure, employing the Mustard procedure in the other 2. Pericardium was used to enlarge the pulmonary venous pathway in the first, second, third, and sixth patients. In the patient with isomerism of the left atrial appendages, and the one with mirror imaged atrial arrangement, the atrial baffle procedures were modified with regard to the individual anatomy.
The connection of the morphologically right ventricle to the pulmonary trunk was constructed with a homograft in 4 patients. Of these, 2 homografts were bicuspidalized, resulting in a diameter of 14 and 16 millimetres, respectively. In the other 2 patients, the size of the implanted grafts was 14, and 15 millimetres. The conduit was placed on the right-hand side of the aorta in all patients. In two patients with double outlet right ventricle and prior banding of the pulmonary trunk (the second and fifth patients), we debanded and enlarged the pulmonary trunk, using a patch, so as to restore the right ventricular outflow tract.
Follow-up
Final follow-up was conducted between March and July, 2005, and was complete with a mean time of 6.5 plus or minus 6.4 years, and a maximum of 17 years. Ventricular function was subjectively assessed by an experienced paediatric cardiologist. Ventricular function was classified as good, moderate, or poor. The presence and degree of tricuspid and mitral insufficiency was evaluated with Doppler echocardiography, and was graded as trivial, mild, moderate, or severe. The ventricular outflow tracts were considered to be moderately or severely obstructed if the maximal instantaneous gradient on echocardiography exceeded 30 over 60 millimetres of mercury. We used the 12-lead resting electrocardiogram for evaluation of cardiac rhythm. Cardiac rhythm was classified as sinus, atrial, or junctional with good chronotropic response, and atrial or junctional rhythm with poor chronotropic response, significant enough to require permanent implantation of a pacemaker. The functional status was determined according to classification adopted by the New York Heart Association.
Statistical analysis
Descriptive data for continuous variables are presented as means plus or minus standard deviation or as medians with ranges; categorical variables are presented as relative frequencies. Analyses were performed with SPSS 12.0.2 for Windows (SPSS Inc., Chicago, Ill.).
Results
Early morbidity
None of our patients died during the initial procedure. Most had a complicated postoperative course, requiring treatment in the intensive care unit for 7 to 24 days, the mean being 12.5 plus or minus 6.2 days. Mechanical ventilation was required for 3 to 16 days, with a mean of 8.0 plus or minus 4.2 days.
There were 2 early reoperations. The first patient, having undergone a Senning operation, developed obstruction of the pulmonary and systemic venous pathways after the anatomic correction, leading to pleural effusions and ascites. She was reoperated for enlargement of the venous pathways on the 5th postoperative day, and remained on mechanical ventilation until the 10th postoperative day. The fourth patient, having undergone a Mustard operation, presented with a baffle leak and stenosis. He was reoperated for enlargement of the systemic venous pathway, and closure of the baffle leak on the 4th postoperative day, and remained on mechanical ventilation until the 16th postoperative day. The second patient, in whom the ventricular septal defect had been enlarged intraoperatively, required implantation of a permanent pacemaker because of complete heart block.
All patients were discharged after the anatomic correction with good left and right ventricular function. The second patient was discharged with moderate left ventricular outflow tract obstruction, and moderate tricuspid insufficiency on diuretics and digitalis. The fourth patient was discharged with moderate tricuspid insufficiency (Table 2).
Table 2. Echocardiographic findings in 6 patients with discordant atrioventricular connections or isomerism of the left atrial appendage after anatomic correction.
Reoperations after hospital discharge
Reoperations were needed in 2 patients after discharge from hospital. The second patient, who had undergone a Senning operation and patch enlargement of the pulmonary trunk, presented with severe obstruction of the morphologically left ventricular outflow tract, a residual ventricular septal defect, moderate mitral insufficiency, obstruction of the systemic venous pathway, and poor left ventricular function 6 months after the anatomic correction. He underwent enlargement of the interventricular communication and revision of the intraventricular patch, enlargement of the systemic venous pathway, and commissural plication of the mitral valve. He died on the day of reoperation from cardiac failure. The sixth patient, who had undergone Senning and Rastelli operations with a homograft, underwent replacement of the homograft, from 15 to 20 millimetres, 7 years after the anatomic correction.
Functional state
The follow-up time of the 5 patients who survived until final follow-up ranged from 1.4 years to 16.7 years, with a median of 7.2 years. Age at follow-up ranged from 2.5 years to 23 years, with a median of 8.3 years. The first, third, and sixth patients are in the first functional class of the categorisation used by the New York Heart Association at periods of 1.4 years, 2.1 years, and 16.7 years after the anatomic correction, respectively. In the fourth and fifth patients, the functional class could not be determined due to neurological comorbidity. The fourth patient developed a cerebral abscess 2 years after the anatomic correction, resulting in hemiplegia, while the fifth patient had congenital microcephaly, resulting in spastic hemiplegia and mental retardation.
Left and right ventricular function was classified as good in each patient. In the sixth patient, moderate tricuspid insufficiency was diagnosed 16 years after anatomic correction at the age of 23. There was only mild tricuspid or mitral insufficiency in the remaining patients. The left and right ventricular outflow tracts were unobstructed in all patients, as were the venous pathways, apart from the fourth patient, who presented with a mean gradient of 9 millimetres of mercury in the pulmonary venous pathway. At final follow-up, all patients were in sinus rhythm (Table 2).
Discussion
Anatomic repair is now recommended for all symptomatic and asymptomatic patients with discordant atrioventricular and ventriculoarterial connections whenever additional lesions are present.8, 16 The patients in our series presented with various abnormal segmental connections. They all had in common that the pulmonary venous blood was predominantly directed to the aorta through the morphologically right ventricle. They were scheduled for anatomic repair because of increasing cyanosis and limitation of physical activity. Anatomic repair was possible because all patients presented with a conditioned morphologically left ventricle, either due to initial obstruction within the subpulmonary outflow tract, or because early banding of the pulmonary trunk had been performed in order to prevent excessive flow of blood to the lungs. In neonates, who presented with significant cyanosis, or in patients with hypoplastic pulmonary arteries, a palliative shunt was placed in order to delay anatomic repair and allow growth of cardiovascular structures. This strategy allowed elective anatomic repair beyond 6 months of age, as recommended by Bove et al.,18 and Ilbawi et al.8
Complete atrioventricular block is the most frequent early complication after anatomic repair. The incidence, as reported in literature, ranges from 0 to 30%.9, 10, 12, 19 Placement of the sutures and enlargement of the ventricular septal defect are crucial technical steps when connecting the morphologically left ventricle to the aorta. Metras et al.19 did not observe any atrioventricular block when performing the intraventricular repair exclusively through the morphologically right ventricle. Incising the superior rim of the ventricular septal defect for enlargement of the interventricular communication was described to be safe because of the anterior location of the conduction tissue.1 Ilbawi et al.8 described slight enlargement of the ventricular septal defect caudally and inferiorly without damaging the conduction tissue. De Leval et al.20 did not find major arrhythmia, when placing the suture line on the morphologically right side of the septum. We also implemented the above outlined techniques. Permanent atrioventricular block occurred in 1 patient, nonetheless, in whom the ventricular septal defect was enlarged. We can only speculate, that this occurred due to mechanical damage by exposing the ventricular septal defect,16 or to the damage of the septal perforating artery supplying the conduction tissue. In order to avoid this complication, Ilbawi et al.8 proposed using the classical repair for patients with a small ventricular septal defect who need a Rastelli operation. Even without surgery, the risk of natural onset atrioventricular block continues at a rate of approximately 2% per year in these patients.21
The placement of the conduit depends on the individual morphology, namely the atrial arrangement, the position of the heart in the chest, and the topographic relationship of the aorta to the pulmonary trunk. Ilbawi et al.8 recommended placing the conduit on the left-hand side of the aorta, except in patients with the aorta positioned to the extreme left. In their opinion, placement to the right side may result in compression of the conduit between the heart and the sternum, as well as compression of the right coronary artery. In our series, nonetheless, in all patients in whom a conduit was implanted, it was placed to the right-hand side, and without complications.
Reoperations are frequent after this complex surgery and are related to all the procedures performed during anatomic correction. We needed to perform reoperations in 2 of our patients with usual atrial arrangement because of baffle complications following the Mustard and Senning operations. This might be related to the fact that both patients had right-sided hearts. In those particular patients, Karl et al.10 recommended augmentation of the pulmonary venous pathway with pericardium when performing the Senning operation. Another patient required reoperation due to obstruction of the left ventricular outflow tract and a residual interventricular communication. He had presented with poor left ventricular function 6 months after the initial operation, and he died from heart failure at the time of reoperation. The combination of pressure and volume load of the ventricle may have lead to rapid systemic ventricular dysfunction. This shows that close follow-up of these patients is warranted. Reoperations to exchange the conduit are inevitable. Whenever possible, therefore, anatomic correction should be postponed, allowing for a larger conduit to be placed during the initial procedure.
Early mortality may be difficult to compare to other studies, because of differences in the timing of anatomic correction, the number of patients, and their associated lesions, and in the surgical approach. The larger series report an early mortality of 0 to 7%, with Duncan et al.15 losing none of 46 patients, Imai et al.22 4 of 44 patients, and Langley et al. 3 of 54 patients.16 Early mortality in smaller series has ranged from 0 to 14%.9–11, 14, 19, 23 In our series of 6 patients, we did not suffer any early death. Hence, the early mortality for the anatomic correction is much less compared to the early mortality of most of the larger series of patients undergoing classical repair, with an early mortality reported of 10 to 20%.5, 24–26
Since the anatomic repair represents a rather new approach, the number of patients available for follow-up is small. Actuarial survival figures have been published by Lanley et al.,16 reporting on 54 patients with a median follow-up of 4.4 years and a maximum follow-up of 9 years. They observed 2 late deaths, at 1 and 3 years after correction. Survival at 4 years was 90%, with no more deaths after this date. In our series, we did not calculate actuarial survival figures, since the number of patients was too small. We observed 1 death at 6 months after correction, albeit that 2 of our other patients have been followed for 11 and 17 years respectively, with both currently in good condition.
Little data exists on the intermediate- and long-term fate of ventricular and atrioventricular valvar function after anatomic correction. Ilbawi et al.8 found normal exercise capacity in the 3 oldest patients of their series, 7 to 10 years after correction. Like Langley et al.,16 they could also show improvement in tricuspid valvar insufficiency in all patients, who presented with moderate or severe tricuspid insufficiency at the time of anatomic correction. In our cohort, left and right ventricular function was preserved, and we found no more than a mild degree of mitral or tricuspid insufficiency in 4 of 5 patients within a mean follow-up time of 6.5 plus or minus 6.4 years and a maximum follow-up time of 17 years.
Early results after the anatomic correction therefore, seem to be superior to the results after the classical repair in terms of the function of the systemic ventricle and the atrioventricular valves. In a study of 24 hospital survivors after classical repair, Sano et al.4 observed severe tricuspid insufficiency in three-tenths of the patients, and deterioration of systemic ventricular function in two-fifths within 3 years after the operation. Similar results were observed by Termignon et al.5 They reported freedom from reoperations for tricuspid insufficiency at 5 years to be less than two-fifths in 15 patients with associated ventricular septal defect, and less than three-fifths in 37 patients with associated pulmonary outflow tract obstruction and ventricular septal defect. These data suggest that anatomic repair may be the more efficient way to prevent systemic ventricular deterioration and progressive dysfunction of the systemic atrioventricular valve than the classical repair.
