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Biomedical subjects

W G Williams

Publications and source records attributed to W G Williams.

At least 19 recordsLinked to original sources
PubMed1998

Total cavopulmonary anastomosis (Fontan) in children with Down's syndrome.

BACKGROUND: There is a paucity of information to guide the management of the child with Down's syndrome and congenital heart disease in whom biventricular repair is precluded. METHODS: Through the cardiology and cardiovascular surgery databases of The Hospital for Sick Children and Toronto Congenital Cardiac Centre for Adults, we identified patients with trisomy 21 and ventricular hypoplasia who had undergone a Fontan procedure (or modification). RESULTS: Of 533 patients who had undergone a Fontan operation between 1976 and 1997, 4 had trisomy 21. All 4 patients had unbalanced complete atrioventricular septal defect with right ventricular hypoplasia in 3 and left ventricular hypoplasia in 1. Three patients survived, and 1 died of endocarditis. The 3 survivors have done well in the short term and medium term without complications related to the pulmonary vasculature. CONCLUSIONS: We suggest that in appropriately selected patients with trisomy 21 and ventricular hypoplasia who are unsuitable for two or one and a half ventricle repair, the Fontan procedure is not contraindicated and provides short-term and medium-term benefit.

Down Syndrome↗
PubMed1998

A practical approach to 1 1/2 ventricle repairs.

BACKGROUND: Perioperative and long-term problems associated with the Fontan circulation are substantial. There has been an exploration of extending the limits of a biventricular ventricular repair by using a superior vena cava-to-pulmonary artery anastomosis. This type of repair is known as a 1 1/2 ventricle repair. METHODS: Patients having defects of the pulmonary ventricle in size or function have undergone 1 1/2 ventricle repairs with or without creation of an atrial septal defect. Repairs with tricuspid z values as small as -10 and predicted pulmonary ventricular volumes as low as 30% have been reported. The 1 1/2 ventricle repair technique has also been used in special situations associated with an arterial switch or double switch procedure. RESULTS: Mortality has ranged from 0% to 12%. Complications have included persistent elevation of superior vena cava pressure, intermittent periorbital edema, and 1 superior vena caval aneurysm requiring takedown. There appears to be an increased risk of perioperative pleural effusions and chylothorax. Protein-losing enteropathy and chronic atrial arrhythmias have not been present. CONCLUSIONS: Successful 1 1/2 ventricle repairs have been reported for morphologically small or poorly functioning pulmonary ventricles and special situations. Intermediate-term follow-up is favorable when compared with reported outcomes for the Fontan circulation.

Anastomosis, Surgical↗
PubMed1998

Primum atrial septal defect in children: early results, risk factors, and freedom from reoperation.

BACKGROUND: Repair of primum atrial septal defect in children usually is associated with a low operative mortality, except for a subgroup of children with congestive heart failure. To determine the early mortality and incidence of reoperation in children with primum atrial septal defect, we analyzed retrospectively the results of patients who underwent repair of this defect. METHODS: Between July 1982 and December 1996, 180 children underwent repair of primum atrial septal defect. The mean age at repair was 4.6 years (median, 3.6 years; range, 1 month to 16.4 years); of the 180 children, 23 were infants less than 1 year of age. Absent or mild symptoms were present in 145 (80%), whereas 34 (20%) of children presented with severe symptoms or congestive heart failure. RESULTS: Early mortality occurred in 3 (1.6%); 2 were less than 1 year of age. Follow-up ranged from 2 months to 14.5 years (mean, 6 +/- 4.2 years). Actuarial survival is 98% at 10 years with no late deaths. Age less than 1 year is a predictor of death. During follow-up, 17 (9%) of the 180 patients underwent reoperation, 5 of whom were in the infant group. Five underwent reoperation for subaortic obstruction, and 12 for left atrioventricular valve regurgitation of whom 11 were repaired; and 1 required valve replacement. Age and preoperative moderate-to-severe left atrioventricular valve regurgitation were predictors of reoperation. CONCLUSIONS: Results of the repair of primum atrial septal defect during childhood are favorable. Infants have a higher risk for death and reoperation. Left atrioventricular valve insufficiency and subaortic stenosis are important late complications and can be repaired safely at reoperation.

Adolescent↗
PubMed1998

Fate of the neopulmonary valve after the arterial switch operation in neonates.

OBJECTIVES: The purpose of this study was to determine the incidence, risk factors, and outcomes of acquired stenosis of the neopulmonary valve after the neonatal arterial switch operation. METHODS: Reviewed were the preoperative and follow-up echocardiograms from 136 of 288 patients undergoing the arterial switch operation for whom adequate studies were available. Pulmonary stenosis was defined as a thickened and doming pulmonary valve and a pressure gradient of 20 mm Hg or more. Transposition of the great arteries was present with intact ventricular septum in 91 patients, with a ventricular septal detect in 39, with an aortic coarctation in 5, and with double-outlet right ventricle in 1 patient. No patient had preoperative valvular abnormalities (i.e., a bicuspid valve). RESULTS: During a median follow-up of 18 months (range <1 to 90 months), 32 patients (24%) had the development of supravalvular pulmonary stenosis, 15 (11%) with associated pulmonary valve stenosis (group I). Kaplan-Meier estimates of freedom from any intervention were 94% (95% confidence interval, 90% to 99%) at 1 year and 79% (95% confidence interval, 64% to 94%) at 5 years. The valve anulus before the arterial switch operation was significantly larger (p < 0.03) in those in whom neopulmonary valve stenosis did not develop (group II) than it was in those in whom it did (group I). At follow-up, the pulmonary valve anulus had decreased significantly in diameter in group I (p < 0.0005) and had remained larger in group II (p = 0.06) compared with normal diameter. Group I patients had the development of significant pulmonary valve hypoplasia (p < 0.03) whereas group II patients continued to have significantly larger valves compared with normal size (p < 0.0001). CONCLUSIONS: Neopulmonary valve stenosis after the arterial switch operation is not uncommon and is associated with growth failure of the valve anulus often associated with supravalvular pulmonary stenosis.

Female↗
PubMed1998

Management and outcomes of right atrial isomerism: a 26-year experience.

OBJECTIVES: We sought to determine, in a large series of patients with right atrial isomerism, factors associated with mortality. BACKGROUND: Right atrial isomerism is associated with complex congenital heart disease and high morbidity and mortality. METHOD: All data from patients diagnosed with right atrial isomerism between January 1970 and March 1996 were reviewed. RESULTS: A total of 91 consecutive patients (54 male) were identified. Most patients (89%) presented within the first month of life, 62% at birth. Cardiac abnormalities included common atrioventricular (AV) valve (81%), ventricular hypoplasia or single ventricle (73%), abnormal ventriculoarterial connections (96%), pulmonary outflow tract obstruction (84%), anomalous pulmonary venous drainage (87%) and pulmonary vein obstruction (30%). The overall mortality rate was 69%. No interventions were planned or performed in 24%, 95% of whom died. The mortality rate for patients requiring their first cardiovascular operation in the neonatal period was 75% versus 51% for those with later first operations (p < 0.05). The surgical mortality rate for patients undergoing pulmonary vein repair was 95%. Overall survival estimates were 71% at 1 month, 49% at 1 year and 35% at 5 years. Independent risk factors for decreased time to death included the absence of pulmonary outflow obstruction (relative risk [RR] 2.23, p < 0.03), presence of major AV valve anomaly (RR 5.23, p < 0.03) and obstructed pulmonary veins (RR 5.43, p < 0.0001). CONCLUSIONS: Right atrial isomerism continues to have an associated high mortality despite surgical innovations. Management of pulmonary vein obstruction remains a serious problem and is associated with high mortality.

Female↗
PubMed1998

Systemic venous collateral development after the bidirectional cavopulmonary anastomosis. Prevalence and predictors.

OBJECTIVES: To determine the prevalence of systemic venous collaterals after the bidirectional cavopulmonary anastomosis and the factors associated with their development. BACKGROUND: Systemic venous collaterals have been found after cavopulmonary anastomosis. Methods. Cardiac catheterization was performed in 103 patients before and after a bidirectional cavopulmonary anastomosis. RESULTS: After surgery, 51 venous collaterals were identified in 32 patients (31%). Collateral development was associated with an abnormal superior vena caval connection (56% incidence vs. 26% with a single right superior vena cava, p = 0.01) and postoperative factors including pulmonary artery distortion (53% incidence vs. 22% without distortion, p = 0.002); increased superior vena caval mean pressure (14 +/- 5 mm Hg versus 11 +/- 4 mm Hg with no collaterals, p = 0.0002); increased pulmonary artery mean pressure (13 +/- 4 mm Hg vs. 11 +/- 4 mm Hg with no collaterals, p = 0.02); lower right atrial mean pressure (5 +/- 2 mm Hg vs. 6 +/- 3 mm Hg with no collaterals, p = 0.04); and increased mean gradient between superior vena cava and right atrium (8 +/- 3 mm Hg vs. 5 +/- 4 mm Hg with no collaterals, p = 0.0002). Using multiple logistic regression, only this last factor was independently associated with collateral development with an odds ratio per 1 mm Hg of 1.33 (95% CI 1.12-1.58, p = 0.001) for their presence. CONCLUSIONS: Systemic venous collaterals occur frequently after a bidirectional cavopulmonary anastomosis and are found postoperatively when a significant pressure gradient occurs between cava and right atrium.

Adolescent↗
PubMed1998

Mortality in potential arterial switch candidates with transposition of the great arteries.

OBJECTIVES: We reviewed the factors contributing to or causing death before surgery in neonates with d-transposition of the great arteries (TGA) despite anatomy suitable for the arterial switch operation (ASO) to develop strategies to minimize preoperative attrition. BACKGROUND: Currently the ASO for neonates with TGA carries a low operative mortality. However, there is a paucity of information regarding the patients who die before the ASO. Strategies to ensure survival to operation are of importance to improve overall outcome. METHODS: We reviewed all neonates with TGA and patent forearm ovale (PFO) < or = 2 mm, a birthweight <2 kg, or who died before surgery, between 1988 and 1996. RESULTS: We identified 12 out of 295 neonates with TGA (4.1%) with anatomy suitable for the ASO who died prior to surgery. All had TGA/intact ventricular septum (IVS) and presented with a severely restrictive PFO. In 11 of 12 cases the cause of death was attributed to the sequelae of profound hypoxemia from inadequate mixing. Contributing factors were prematurity, 41.7%; severe respiratory distress syndrome, 25%; and persistent pulmonary hypertension of the newborn (PPHN), 16.7%. All patients received prostaglandin E1 (PGE1) infusion. Urgent balloon atrial sepstostomy (BAS) was performed in 66.7% with improved oxygenation. No cases were diagnosed prenatally. In contrast, all patients with a PFO < or = 2 mm who survived to ASO had a significantly better response to PGE1 infusion (p=0.03) than nonsurvivors. The ASO was accomplished without mortality in four of nine with a weight <2 kg. CONCLUSIONS: Of those neonates admitted with TGA, 4.1% died before surgery. Eleven of 12 (3.7%) died due to consequences of inadequate interatrial mixing despite PGE1 infusion. Earlier diagnosis and BAS are critically important in determining survival. Early ASO may improve survival in patients weighing <2 kg. Prenatal diagnosis with delivery in a high-risk obstetrical unit with facilities for immediate BAS and supportive therapy for pulmonary hypertension and ventricular failure may be necessary to salvage this group of patients.

Cause of Death↗
PubMed1997

Complete atrioventricular septal defects: results of repair, risk factors, and freedom from reoperation.

BACKGROUND: Several perioperative risk factors influence outcomes after repair of complete atrioventricular septal defects. This study was conducted to determine their association with perioperative mortality and need for reoperation. METHOD AND RESULTS: Between July 1982 and February 1995, 363 children underwent defect repair (median age, 8.3 months; mean, 17.4+/-1.3). Tetralogy of Fallot was present in 21 patients, double-outlet right ventricle in 4, subaortic stenosis in 8, ventricular hypoplasia in 8, coarctation in 5, atrial isomerism in 2, and other congenital anomalies in 9. Down's syndrome was present in 235 (65%). One-patch technique was applied in 99, two-patch in 243. During repair, the anterior bridging leaflet was divided in 12, the posterior bridging leaflet in 31, both leaflets in 71, and neither in 249. Left atrioventricular valve (LAVV) cleft was closed partially in 181 and completely in 112. Early mortality was 10.5%; 10-year survival, 83% (95% confidence interval, 0.79 to 0.87). At 10 years, freedom from reoperation for LAVV repair was 86%; LAVV replacement, 90%; subaortic stenosis, 95%; residual ventricular septal defect, 97%; permanent pacemaker insertion, 98%; and other types of reoperation, 95%. At the time of operation, greater age, shorter ischemic time, absence of a double-orifice LAVV, and cleft closure were found to be significant independent predictors of survival. CONCLUSIONS: Repair of atrioventricular septal defects has acceptable early and late mortality and a low incidence of reoperation. Double-orifice LAVV remains a risk factor. Repairs that include complete cleft closure may confer better survival.

Follow-Up Studies↗
PubMed1997

Sustained ventricular tachycardia in adult patients late after repair of tetralogy of Fallot.

OBJECTIVES: We sought to determine the features associated with sustained monoform ventricular tachycardia (VT) in adult patients late after repair of tetralogy of Fallot (TOF) and to review their management. BACKGROUND: Patients with repair of TOF are at risk for sudden death. Risk factors for ventricular arrhythmia have been identified from patients with ventricular ectopic beats because of the low prevalence of sustained VT. METHODS: From a retrospective chart review of patients assessed between January 1990 and December 1994, 18 adult patients with VT were identified and compared with 192 with repaired TOF free of sustained arrhythmia. RESULTS: There was no significant difference in age at repair, age at follow-up or operative history. Patients with VT had frequent ventricular ectopic beats (6 of 9 vs. 21 of 101), low cardiac index ([mean +/- SD] 2.4 +/- 0.4 vs. 3.0 +/- 0.8) and more structural abnormalities of the right ventricle (outflow tract aneurysms and pulmonary or tricuspid regurgitation) than control patients. Electrophysiologic map-guided operation was performed in 10 of 14 patients who required reoperation. VT has reoccurred in three of these patients. Four patients did not undergo operation (three received amiodarone; one underwent defibrillator implantation). Two patients with VT also had severe heart failure and died. CONCLUSIONS: Most patients with VT late after repair of TOF have outflow tract aneurysms or pulmonary regurgitation, or both. These patients have a greater frequency of ventricular ectopic beats than arrhythmia-free patients after repair of TOF. A combined approach of correcting significant structural abnormalities (pulmonary valve replacement or right ventricular aneurysmectomy, or both) with intraoperative electrophysiologic-guided ablation may reduce the potential risk of deterioration in ventricular function and enable arrhythmia management to be optimized.

Adult↗
PubMed1997

Overexpression of transforming growth factor-beta1 and insulin-like growth factor-I in patients with idiopathic hypertrophic cardiomyopathy.

BACKGROUND: Idiopathic hypertrophic cardiomyopathy (HCM) is characterized by regional myocardial hypertrophy. To investigate involvement of growth factors on myocardial hypertrophy in HCM patients, we evaluated gene expression and cellular localization of transforming growth factor-beta1 (TGF-beta1), insulin-like growth factors (IGF-I and IGF-II), and platelet-derived growth factor-B (PDGF-B) in ventricular biopsies obtained from patients with HCM (n=8), aortic stenosis (AS) (n=8), or stable angina (SA) (n=8) and from explanted hearts with ischemic cardiomyopathy (TM) (n=7). METHODS AND RESULTS: Levels of TGF-beta1, IGF-I, IGF-II, and PDGF-B transcripts were quantified with the use of multiplex RT-PCR. Glyceraldehyde 3-phosphate dehydrogenase was used as an internal standard. Antibodies against TGF-beta and IGF-I were used to localize their peptides within the myocardium. Antisense and sense (control) cRNA probes of TGF-beta1 and IGF-I, labeled with digoxigenin, were used to localize the growth factor transcripts by in situ hybridization. mRNA levels (densitometric ratio of growth factor/glyceraldehyde-3-phosphate dehydrogenase) of TGF-beta1 and IGF-I in HCM (0.75+/-0.05 and 0.85+/-0.15, respectively; mean+/-1 SEM) were significantly (P<.01 for all groups) elevated in comparison with non-HCM myocardium (AS: 0.38+/-0.07, 0.29+/-0.06; SA: 0.32+/-0.04, 0.18+/-0.05; TM: 0.25+/-0.03, 0.15+/-0.03). mRNA levels of TGF-beta1 and IGF-I in the hypertrophic AS myocardium were greater (P=.02, P=.05) than those in the explanted myocardium (TM). Immunohistochemical and in situ hybridization studies showed increased expression of TGF-beta1 and IGF-I in the HCM cardiomyocytes. CONCLUSIONS: Gene expression of TGF-beta1 and IGF-I was enhanced in idiopathic hypertrophic cardiomyopathy and may be associated with its development.

Aged↗
PubMed1997

Transcatheter perforation of the right ventricular outflow tract as initial therapy for pulmonary valve atresia and intact ventricular septum in the newborn.

The clinical impact of transcatheter perforation and dilatation of the right ventricular outflow tract in neonates with pulmonary atresia and intact ventricular septum was reviewed. Between April 1992 and December 1994, 8 neonates underwent transcatheter perforation of the right ventricular outflow tract. Radiofrequency energy was employed in 6 patients and wire perforation in 2 patients. Mean patient age at intervention was 1.9 +/- 0.6 days and weight 3.4 +/- 0.5 kg. Median tricuspid valve annulus was 10.9 mm (range: 4.0-13.0 mm) and Z-value -0.85 (range: -4.5-1.0). The mean right ventricular systolic pressure fell from 117 +/- 16 to 55 +/- 15 mm Hg (P < 0.0001), and the right ventricular to aortic pressure ratio decreased from 1.81 +/- 0.33 to 0.82 +/- 0.28 (P < 0.0001). The arterial duct was patent in all. No acute complications occurred. Aortopulmonary shunts were performed in 7 patients at a median 6 days (range: 3-23 days) following catheterization. One patient developed sepsis and died after surgical resection of infected tissue, while a second patient died of a blocked aortopulmonary shunt 17 months following discharge. Median follow-up for the 6 surviving patients was 8 months (range: 4-32 months). One patient has achieved and a second is awaiting biventricular repair. Transcatheter perforation appears to be a promising form of therapy in selected patients with pulmonary atresia, and potentially facilitates algorithms leading to a biventricular repair.

Angioplasty, Balloon↗
PubMed1997

Pediatric primary benign cardiac tumors: a 15-year review.

An increase in the incidence of primary cardiac tumors has been reported since the development or enhancement of noninvasive imaging modalities. We identified 56 children with primary cardiac tumors. Forty-four (78%) children had rhabdomyomas, 6 (11%) fibromas, 1 (2%) pericardial teratoma, 1 (2%) epicardial lipoma, 1 (2%) multicystic hamartoma, and 3 (5%) unspecified tumors. The mean age at diagnosis was 19 +/- 35 months (median 4.7 months, range 0.03 to 204 months), excluding 12 patients who were given the diagnosis before birth. Among 27,640 patients assessed for cardiac disease, the incidence of tumors was 0.06% (1980 to 1984), 0.22% (1985 to 1989), and 0.32% (1990 to 1995). Diagnosis was made in 55 of 56 patients by echocardiography. Catheterization was performed in five patients and magnetic resonance imaging in nine. No tumor-related deaths occurred. Nine patients had surgery because of hemodynamically significant obstruction or arrhythmias. Partial or complete regression occurred in 24 (54%) of 44 patients with rhabdomyomas. Overall, the prognosis was excellent. Individualized surgery allowed early safe treatment of symptomatic tumors.

Child↗
PubMed1997

Effect of heparin loading during congenital heart operation on thrombin generation and blood loss.

BACKGROUND: The heparin protocols used during cardiopulmonary bypass (CPB) in children undergoing surgical repair for congenital heart disease are extrapolated from adult data. Studies are needed that assess the optimal heparin dosing in these children, whose heparin clearance is increased compared with that in adults. METHODS: We assessed the effects of two commonly used doses of heparin in the prime solution at the start of CPB operation on plasma heparin levels, on thrombin production (thrombin-antithrombin III complexes, prothrombin fragment 1 + 2, D-dimer, and antithrombin III), and on the risk of hemorrhage. Before CPB, 48 children with congenital heart disease received heparin intravenously in a loading dose of 300 U/kg, followed by either 1 U/mL of heparin in the prime (low-dose group: 22 patients-acyanotic, 9; cyanotic, 13) or 3 U/mL of heparin in the prime (group: high-dose, 26 patients-acyanotic, 15; cyanotic, 11). RESULTS: In all patients, CPB resulted in the generation of thrombin. The duration of CPB was a significant covariate factor for heparin levels (p = 0.002), thrombin production (p < 0.001), and postoperative blood loss (p < 0.001). In the patients in the high-dose group, the total heparin dose and the plasma heparin levels were higher (p = 0.0005 and 0.005, respectively) and the D-dimer levels tended to be lower (p = 0.06). The postoperative blood loss was higher in the cyanotic patients (p = 0.02; both high-dose and low-dose groups), with 2 cyanotic patients (1 in low-dose group, 1 in high-dose group) requiring reoperation, one of whom subsequently died. The increased heparin dose had no significant effect on the rate or volume of postoperative blood loss. CONCLUSIONS: Increasing the heparin dose in the prime solution from 1 to 3 U/mL increased the plasma heparin levels and showed a trend toward reducing the postoperative laboratory values indicative of fibrinolysis. Thrombin generation during CPB and the incidence of postoperative hemorrhage were not significantly altered. Larger randomized trials are needed to determine the optimal heparin-dosing regimen in patients with congenital heart disease.

Adolescent↗
PubMed1997

Pulmonary atresia with intact ventricular septum: results of the Fontan procedure.

BACKGROUND: Children with pulmonary atresia and an intact ventricular septum show a heterogeneous spectrum of cardiac anomalies. A biventricular repair is attainable in some; a Fontan procedure or a one-and-a-half ventricle is the only possible repair for others. Children with right ventricle-to-coronary artery connections, with or without right ventricle-dependent coronary artery blood flow, are a high-risk group. METHODS: Between May 1980 and December 1994, 22 children underwent a Fontan operation for the treatment of pulmonary atresia with an intact ventricular septum at The Hospital for Sick Children, Toronto. The mean age was 5.8 years (median, 4.9 years). All children had had at least one pre-Fontan palliative procedure; 19 had two, and 7 of these had three or more. Right ventricle-to-coronary artery connections were present in 15 children, including 5 with right ventricle-dependent coronary artery blood flow. Thromboexclusion of the right ventricle was done in 10 children, with 7 undergoing it before and 3 at the time of the Fontan procedure. RESULTS: There were three early deaths (13.6%) and one late death. The actuarial survival at 10 years after the Fontan operation was 80%. Early postoperative complications occurred in 4 children. Follow-up was completed in all children at a mean of 4 years (range, 1 to 12.5 years) after the Fontan operation. Atrial arrhythmia occurred in 3 children, and permanent pacemakers were required in 4. CONCLUSIONS: Results of the Fontan operation for the treatment of pulmonary atresia with an intact ventricular septum are satisfactory. Thromboexclusion of the right ventricle is indicated in the presence of right ventricle-to-coronary artery connections without right ventricle-dependent coronary artery blood flow. The right ventricle should not be decompressed or thromboexcluded in children with right ventricle-dependent coronary artery blood flow, and at the Fontan operation, saturated blood must enter the right ventricle.

Child, Preschool↗
PubMed1997

Pulmonary valve replacement late after repair of tetralogy of Fallot.

BACKGROUND: Pulmonary valve incompetence is usually well tolerated after tetralogy of Fallot repair but may result in late progressive right heart failure as manifested by increasing fatigue, dyspnea, and frequently arrhythmias. METHODS: All patients who underwent pulmonary valve replacement in our center late after repair of tetralogy of Fallot were reviewed. RESULTS: Eighty-five patients had elective pulmonary valve replacement late (median, 9.3 years) after repair. Operative risk was low (1.1%). Ninety percent of survivors are in New York Heart Association class I. Survival 10 years after pulmonary valve replacement is 95%, with 86% of the patients free of reoperation for valve failure. CONCLUSIONS: Pulmonary valve replacement is infrequently required after repair of tetralogy of Fallot. Pulmonary valve replacement may be performed electively with little risk; it improves symptoms of right heart failure and provides satisfactory long-term survival with low risk of early valve failure. As the population of patients who have had repair of tetralogy of Fallot ages, pulmonary valve replacement will become a more frequent consideration.

Adolescent↗
PubMed1997

Outflow obstruction after the arterial switch operation: a multiinstitutional study. Congenital Heart Surgeons Society.

OBJECTIVE: Our objectives were to discover whether outflow obstruction immutably accompanies the arterial switch operation and to identify factors that may decrease its prevalence. METHODS: Percutaneous or surgical reintervention for obstruction after an arterial switch was selected as an end point for obstruction. Its risk factors were identified by time-related multivariable analyses of yearly follow-up data from 514 neonates with simple transposition or transposition with ventricular septal defect entering 23 institutions before 15 days of age between January 1, 1985, and March 1, 1989. RESULTS: Sixty-two patients underwent 86 reinterventions for right-sided obstruction (83% free at 10 years) and six for left-sided obstruction (98% free at 10 years). After 2 years, right-sided obstruction occurred at a rate of about 1% per year and left-sided at a rate of about 0.1% per year. Right ventricular infundibular or valvular obstruction was associated with the aorta and pulmonary trunk positioned side-by-side, coexisting coarctation, use of prosthetic material in sinus reconstruction, one institution, and earlier institutional experience. Pulmonary trunk or pulmonary artery obstruction was associated with lower birth weight, left coronary artery arising from sinus 2, coronary explantation away from the transection site, three institutions, and earlier institutional experience. CONCLUSIONS: A risk-adjusted base incidence (0.5% per year) of reintervention for right-sided obstruction continues late after operation. It is due in part to congenital variability or abnormality of right ventricular outflow structures and to experience and surgeon variability resulting in suboptimal pulmonary trunk reconstruction. The same sources of variability probably affect the aortic root, but its native characteristics plus higher distending pressure make the base incidence considerably less (0.1% per year).

Cross-Sectional Studies↗