We evaluated the physical characteristics of the pulmonary trunk in 32 patients with complete transposition after the arterial switch operation, calculating the pulmonary input impedance. In 6 of the patients, the characteristic impedance was equal to, or less than, the value in patients with ventricular septal defect. In those patients with an intact ventricular septum, or those with a ventricular septal defect who had undergone the arterial switch operation or banding of the pulmonary trunk before 3 months age, the frequency of the first modulus minimum also agreed with the values obtained in patients with ventricular septal defect. The value was high, however, in patients with complete transposition with ventricular septal defect who had undergone an arterial switch operation or banding of the pulmonary trunk after 4 months of age. Our data suggest decreased distensibility of the proximal pulmonary trunk after the arterial switch operation, and mild changes in the pulmonary vasculature in patients with complete transposition with ventricular septal defect who had undergone either an arterial switch operation or banding of the pulmonary trunk after 4 months of age. Long-term follow-up is needed clarify whether or not these features affect right ventricular function by means of an increase in afterload.

Despite early arterial switch repair of complete transposition of the great vessels, significant physiologic aberrations may still occur. Two cases of vascular disease in the left pulmonary arterial system are described and potential mechanisms are discussed. We conclude a small number of children with simple transpostion may develop asymmetric patterns of pulmonary blood flow without evidence of anatomic narrowing of either arterial vessel.

In western Sweden, less than one-third of children born with complete transposition between 1964 and 1983 are long-time survivors. During bicycle ergometry, using a steady-state protocol with analyses of the expiratory gases and lactate, we investigated the exercise capacity in survivors of atrial redirection. There were 16 patients who had a Mustard procedure, now aged 16.9±3.6 years (12.0–22.0) and 15 patients who underwent a Senning correction aged 9.4±1.6 years (7.2–12.1). Nineteen percent of Mustard cases and 53% of Senning cases had minor or no sequels. Moderate sequels were found in 44% of post-Mustard cases, and 40% of post-Senning cases, including baffle complications, moderate systemic ventricular dysfunction, sinus node dysfunction and tracheal stenosis. Severe problems were encountered in 37% of post-Mustard cases and 7% of post-Senning cases, including pulmonary hypertension, pulmonary venous obstruction, atrioventricular block and hemiparesis. The maximal exercise capacity was low (p<0.0001); 71% had an oxygen uptake below −2 SD of predicted values, with severely impaired oxygen uptake in all except one of the cases with severe sequels, but no significant difference was found between patients having mild and moderate sequels. The maximally achieved heart rate was low (p<0.0001); 71% had values below −2 SD of predicted, including all cases with sinus nodal dysfunction, as well as 40% of cases without it. The maximal oxygen pulse was low (p<0.01), below −2 SD in 36%, but it was less affected than other exercise variables in 68% of the patients. Our study, therefore, presents exercise data in an epidemiologically-based population, relates the data to postoperative sequels and discusses some possible adaptive mechanisms.

Long-term follow-up studies after intraatrial repair for complete transposition have shown postoperative morphologic and hemodynamic abnormalities in many patients which often require reevaluation and therapeutic intervention. The purpose of this study was to assess, using magnetic resonance imaging, the presence and extent of late postoperative complications in a large cohort of 44 patients undergoing repair with the Mustard procedure. Of these 34 had an intact ventricular septum with or without obstruction of the left ventricular outflow tract, while 10 had an associated ventricular septal defect. Transverse spin-echo and gradient-echo images were acquired of the entire heart from the diaphragm to the bifurcation of the pulmonary trunk. Additional oblique images were acquired for better visualization of venous connections. Abnormal findings were diagnosed by visual inspection of spin-echo and gradient-echo images, and diagnoses were compared to previous findings at cardiac catheterization. On magnetic resonance imaging, a baffle leak was seen in eight patients, two had pulmonary venous obstruction, four had obstruction at the caval veins, 23 had obstruction of the left ventricular outflow tract and 18 had tricuspid regurgitation. Cardiac catheterization showed a leak across the baffle in 16, pulmonary venous obstruction in two, obstruction at the caval veins in four, obstruction of the left ventricular outflow tract in nine, and tricuspid regurgitation in nine. We conclude that combined spin-echo and gradient-echo magnetic resonance imaging provides extensive noninvasive assessment of postoperative sequels and residuals in patients after the Mustard procedure for complete transposition.

Stenoses of the systemic venous pathways are a potentially dangerous complication after the Mustard operation. The acute and intermediate-term efficacy of balloon dilation of these stenoses has not previously been studied in a large group of patients. A retrospective analysis of clinical and angiographic data, with prospective clinical and echocardiographic follow-up, was performed in a consecutive group of 25 patients (17 male, 8 female) who underwent balloon dilation of the superior or inferior caval venous pathways. For 17 dilations of stenoses in the superior pathway, the mean pressure gradient decreased from 9.1±5.7 to 3.4±2.3 mm Hg (p<0.01), while the diameter of the stenosis increased from 5.9±2.9 to 11.2±3.0 mm (p<0.01). For 25 dilations of the inferior pathway, the mean gradient decreased from 4.3±1.8 to 1.4±1.1 mm Hg (p<0.01), while the diameter of the stenosis increased from 7.3±1.5 to 10.6±2.3 mm (p<0.01). Over a median follow-up of 3.5 years, 16 patients have been without symptoms or signs suggestive of recurrence of stenoses. In the remaining nine patients, 11 further procedures were performed at a median of 3.1 years after initial dilation. In five patients who had previously undergone dilation of the superior (3), inferior (1) or both (1) pathways, further dilations of the same pathway(s) and/or stent implantations were performed. Three patients, including one in whom superior caval venous stenosis had recurred, had developed a new stenosis of a previously undilated pathway, while in two patients no further dilations were required. Balloon dilation offers an alternative to reoperation for stenoses of the systemic venous pathways after the Mustard operation, and appears to provide satisfactory intermediate-term palliation. Recurrences of stenoses in previously dilated pathways, and new stenoses in previously unobstructed pathways, are commonly seen at follow-up. Alternative measures, such as placement of stents, need to be considered in the long-term management of these patients.

A patient with complete transposition and a ventricular septal defect was clinically improved by an atrial septectomy at nine years but continued sepsis in the thoracotomy scar resulted in blood-stream infection with Staphylococcus aureus at the age of 24 years. A deep nylon suture was found and removed at surgical exploration. Five months later she again became febrile and had a vasculitic skin rash which responded to antibiotic therapy. At that time she was cyanosed and had a restricted exercise tolerance and was found to have aneurysmal dilatation of the pulmonary trunk. A year later she had acute chest pain with increased breathlessness, fever, hepatomegaly and pulmonary regurgitation. The fever did not respond to antibiotic therapy and she died suddenly following removal of a Hickman line. At postmortem examination, there was found to be a false aneurysm in the mediastinum due to rupture of the aneurysmal pulmonary trunk. No evidence of infection was found and it was considered that the low grade pyrexia had been due to the large hematoma within the false aneurysm.

The role of cross-sectional echocardiography is demonstrated in defining the anatomy of the coronary arteries in 29 patients with complete transposition (concordant atrioventricular and discordant ventriculoarterial connections). The study revealed a relationship between some of the less frequent patterns and the spatial relationship of the arterial trunks, along with the presence or absence of a ventricular septal defect. It suggests that a side-by-side relationship of the arterial trunks due to infundibular maldevelopment may be related to some of the less common patterns.

Atrial correction for complete transposition involves a potential risk of later development of right ventricular dysfunction. To determine the reasons contributing to such systemic ventricular failure, radioisotope first-pass and SPECT perfusion studies at rest after one dose of Technetium-99m MIBI were performed in 26 asymptomatic patients, 5.9±2.7 years after a Mustard or Senning repair. Mean age at operation was 4.3±4.3 years. All patients were followed with 24-hour Holter monitoring and echocardiography. Normal perfusion was observed in 11 patients with a mean age at operation of 2.25±1.8 years and mean right ventricular ejection fraction of 49.0±8.7%. Perfusion defects were found in 15 patients with a mean age at operation 5.8±4.8 years (p<0.05) and mean right ventricular ejection fraction of 43.2±9.3% (NS). In the group of older patients, 10 had extensive perfusion defects with significantly lower right ventricular ejection fraction (39.7±9.3%, p<0.05) and even older mean age at the surgery (7.1±5.6 years p<0.02). Mild or moderate tricuspid regurgitation was found significantly more frequently in those patients with perfusion defects (73%) than in the group of younger patients (36.3%), p<0.05. There was no difference in the frequency and type of arrhythmias, nor in the extent of follow-up, between the two groups. We conclude that, in patients undergoing surgery at an older age, it is more common to find perfusion defects and, often, lower right ventricular ejection fraction. Perfusion abnormalities found in such asymptomatic patients may be a result of several factors: impaired right ventricular function as a consequence of pressure and volume overload, enhanced myocardial fibrosis, or long-lasting preoperative hypoxemia and tricuspid valvar dysfunction secondary to ventricular dilation. We suggest that the perfusion defects observed in this study may be a better indicator of systemic ventricular impairment.

Between December 1982 and April 1991, balloon atrial septostomy was performed in the intensive care unit under echocardiographic control in 60 neonates. Of the patients, 58 had complete transposition. Two patients had double outlet right ventricle with a sub-pulmonary ventricular septal defect. Associated lesions included a patent arterial duct in 19 patients, ventricular septal defect in nine, obstruction of the left ventricular outflow tract in six, aortic coarctation in two and tricuspid atresia in one. The mean age at septostomy was four days (range 4 hours - 25 days) and the mean weight 3.19 kg (range 1.17–4.25 kg). In 39 (65%) patients, an infusion of prostaglandin was in progress prior to the septostomy and 22 (37%) were being ventilated. Standard subcostal four-chamber echocardiographic views were used to show the atrial septum and to guide the catheter used for septostomy. Venous access was obtained via the femoral vein in 43 (by percutaneous puncture in 40 and by cutdown in three) and the umbilical vein in 17. Transient atrial arrhythmias were common during the septostomy but no acute hemodynamic disturbances or deaths occurred during the procedure. The size of the atrial septal defect as measured by echocardiography after the septostomy ranged from three to 12 mm in diameter. In only one patient was this inadequate. Three (5%) patients died between two and 10 days after the septostomy, two due to necrotizing enterocolitis and one from persistent hypoxemia. One patient had a cerebral thrombosis and convulsions immediately after the septostomy but made a good neurological recovery. Corrective surgery was performed in 52 (86.6%), two (3.3%) had palliative surgery and two were considered unsuitable for total correction, of whom one has died. One patient died whilst awaiting correction. We conclude that balloon atrial septostomy using echocardiographic guidance can be safely and effectively performed in the intensive care unit.

The arterial switch operation is the treatment of choice for complete transposition, and for the Taussig-Bing anomaly, with good early and mid-term results. This retrospective study examined the findings obtained at routine follow-up cardiac catheterization after primary arterial switch repair. We catheterized 111 patients after a mean of 16.9 months after surgery. These included 67 patients with an intact ventricular septum, 33 with a ventricular septal defect, and 11 with the Taussig-Bing anomaly. Right ventricular pressures were mildly elevated (mean 33.9±10.2 mm Hg) in the overall group with a mean pressure ratio between right and left ventricles of 0.34±0.1. Of the patients 74% had gradients across the right ventricular outflow tract of under 20 mm Hg, while three (2.7%) had gradients over 30 mm Hg. A significant gradient across the left ventricular outflow tract occurred in one patient (0.9%), while significant neo-aortic stenosis was not seen. The neo-aortic root remained dilated, with mild aortic valvar incompetence being seen in 12%, with none having higher grades of regurgitation. Left ventricular ejection fraction was normal in all patients, while left ventricular end-diastolic pressure was elevated in 38%. Coronary arterial stenosis was not seen, but one patient (0.9%) had left ventricular apical dyskinesia. Overall, therefore, we conclude that cardiac hemodynamics and ventricular systolic function after primary arterial switch are good. Minor gradients to the pulmonary arteries, and mild neo-aortic valvar incompetence were commonly noted. Left ventricular end-diastolic pressure was elevated in over a third of the patients. These subclinical and subtle abnormalities warrant ongoing follow-up to determine their long-term significance.

The long-term natural progression of cardiac rhythm and the incidence of serious arrhythmias in relation to previous procedures and associated heart defects were studied in a group of 76 patients after an arterial switch operation for complete transposition and compared to a group of 24 patients who had undergone intraatrial corrections (Mustard or Senning operation). Standard and 24-hour ambulatory electrocardiograms were reviewed. Mean follow-up was 7.9 years (range 2-16) after an arterial switch and 15.2 years (range 6-26) following the Mustard or Senning procedures. One patient died after an arterial switch from pulmonary hypertension (age 9.9 years), and three patients died suddenly, presumably from arrhythmias, following atrial redirection procedures (ages 13, 18 and 20 years). Symptomatic arrhythmias were not seen after the arterial switch operation. Three patients required pacemaker implantation after atrial redirection, and a further two required medication to control tachyarrhythmias. Survival analysis of sequential electrocardiograms showed a mean maintenance of sinus rhythm during 12.9 years (95% confidence interval 11.4-14.5) after the arterial switch and 9.0 years (7.3-10.7) after atrial procedures (p=0.003). Development of heart rate was significantly different (p=0.001), with higher rates in adolescents after an arterial switch. Twenty-four-hour recordings were abnormal in five of 72 patients following arterial correction, disclosing excessive ventricular extrasystoles in four (three monomorphic, one polymorphic) and a wandering pacemaker in one. After atrial procedures, 11 of 19 were abnormal (p<0.001), with sinus or atrial bradycardia in eight, atrial flutter in two, and monomorphic ventricular tachycardias in one. Abnormal findings on either 12-lead or 24-hour electrocardiograms were seen in 22% of patients following an arterial switch procedure and 83% of patients undergoing atrial redirection (p<0.001). Sinus rhythm, therefore, is preserved longer and arrhythmias are less frequent and less severe after the arterial switch operation than after the Mustard or Senning operations.

Aortic atresia is rare in the setting of a normally developed left ventricle with a ventricular septal defect. In this combination, as far as we know, it has been described only with concordant ventriculo-arterial connections, for which seven one-stage biventricular repairs have now been described. We describe here the case of a 3½-month-old male infant with a similar combination but with discordant ventriculo-arterial connections and severe pulmonary hypertension. It was the right ventricle which achieved normal size in this arrangement, presumably because of the ventricular septal defect. One-stage biventricular correction was accomplished, employing a single pulmonary allograft, aided by massive doses of Prostaglandin El. As far as we know this is the first report of the combination of aortic atresia, discordant ventriculo-arterial connections, a ventricular septal defect and balanced ventricles. We complement our surgical account, nonetheless, with a description of a comparable specimen from our anatomic museum.

The use of an obstructing balloon catheter positioned in the outflow tract of the pulmonary ventricle may be an alternative method for the adaptation of the left ventricle to an increased afterload prior to an arterial switch procedure in patients with complete transposition requiring a two-stage approach. We tested this approach in an acute hemodynamic study in a piglet model. Seven piglets were anesthetized with halothane and ventilated at FiO2 1.0. Through a median sternotomy, the great vessels were exposed. The right ventricular pressure and the aortic blood pressure were recorded using microtip manometers, cardiac output was measured by an electromagnetic flow probe on the ascending aorta. A 6F or 7F Berman angiographic catheter was placed in the lumen of the pulmonary artery and the balloon inflated to decrease cardiac output no more than 30%. The hemodynamic changes observed after balloon inflation included an 100% increase in systolic right ventricular pressure (control vs balloon inflation (mean±SE) 20.4 ± 1.5 mm Hg vs 46.6 ± 4 mm Hg, p<0.001), a slight reduction in systolic aortic pressure (75.5 ± 3.8 mm Hg vs 65.0 ± 5.8 mm Hg; p<0.05), and a reduction in cardiac output by 30% (1.1 ± 0.081/min vs 0.8 ±0.08 1/min, p<0.01). The systolic right ventricular to aortic pressure ratio was increased from 0.27 ± 0.02 to 0.69 ± 0.08, p<0.001. This study shows that a balloon catheter may be useful in creating systolic hypertension in the pulmonary ventricle in patients with complete transposition requiring a two-stage approach.

This study was designed to determine, first, the stiffness of the pulmonary arteries and, second, the relationship between the stiffness of the pulmonary arteries and the success rate of balloon angioplasty in patients with complete transposition after an arterial switch operation. Indexes of pulmonary arterial wall stiffness, percent change in the radius during a cardiac cycle and the pressure elastic modulus, were calculated from the pulmonary arterial pressure and radius measured from a cineangiogram. Of the patients, 13 had no significant stenosis, while 25 had significant stenoses and, therefore, underwent balloon angioplasty. In all, we dilated 33 stenotic lesions. In the presence or absence of postoperative pulmonary stenosis, the percent change in the radius of the pulmonary trunk was significantly less than the normal value. The pressure elastic modulus of the trunk and its branches was significantly greater than normal, and increased significantly with time after the operation. In patients without pulmonary stenosis, the systolic pulmonary arterial pressure increased concomitantly with the pressure elastic modulus. Balloon dilation was successful at 17 locations and unsuccessful at 16 locations. The percent change in radius was significantly less for the failures than for the successes. Prior to 3.5 years after the operation, the pressure elastic modulus was < 400 g/cm2 at most locations and balloon dilation was successful in 88%. More than 3.5 years after the operation, the pressure elastic modulus was < 400 g/cm2 in 11 of 15 locations, and balloon dilation was successful in only one location. The increased stiffness of the pulmonary artery may result in increased pulmonary systolic pressure in patients without pulmonary stenosis, and result in a low success rate for balloon angioplasty in patients with pulmonary stenosis.

For the visualization of the coronary arterial patterns in complete transposition (concordant atrioventricular and discordant ventriculoarterial connections), balloon occlusion aortography has been performed in right and left anterior oblique or in frontal and lateral views. These views, however, are often unsatisfactory because of super-imposition of the aortic sinuses. The so-called “laid-back” view is a newly developed angiographic projection in which the aortic sinuses and the intervening commissures are imaged as if they were seen from below and the front. We performed such laid-back aortography in 36 consecutive patients with an echocardiographic diagnosis of complete transposition. In 23 of 36 patients, we obtained additional aortograms in right and left anterior oblique views. For the evaluation of the diagnostic value of the laid-back view, as compared with that of the combined right and left anterior oblique views, both sets of aortograms were reviewed independently by the five reviewers who were asked to make a diagnosis and to specify their levels of confidence (“definite,” “probable,” and “possible”) for their diagnosis. Error rates were significantly lower for the laid-back aortograms than for the combined right and left aortograms (4 and 11%, respectively). An increased level of confidence was significantly associated with the laid-back aortograms. We illustrate the anatomy of various coronary arterial patterns seen by laid-back aortography.

We report our experience of aortic valvar replacement subsequent to the arterial switch procedure, incorporating the Lecompte maneuver, in patients with complete transposition. The anterior wall of the neoaorta was incised in continuity with the posterior wall of the pulmonary trunk. The aortic root was reconstructed with or without augmentation using a patch after the operative procedures to the aortic valve. With this approach, the neoaortic root could readily be exposed without extensive dissection, and valvar replacement was safely achieved. These patients experienced no postoperative complications.