Vincent R. Zales

Coarctation of the Aorta Repair With Polytetrafluoroethylene Patch Aortoplasty

BACKGROUND The first successful surgical repair of coarctation of the aorta (CoAo) was performed in 1944, but during the years that followed a high incidence of recoarctation was seen, ranging from 20% to 86%. In response to that problem, the patch aortoplasty was introduced in 1957; however, true aneurysms were found in the aortic wall opposite the patch after Dacron patch aortoplasty, particularly when the coarctation ridge was excised. The purpose of our review was to evaluate the results of patch aortoplasty for CoAo using a relatively new material, polytetrafluoroethylene (PTFE), and an operative technique that does not involve resection of the coarctation ridge. METHODS AND RESULTS Between 1979 and 1993, 125 infants and children underwent PTFE patch aortoplasty for CoAo; 111 of the procedures were primary repairs, and 14 were reoperations. Diagnoses were isolated CoAo (96 patients), CoAo and ventricular septal defect (15 patients), and CoAo with complex intracardiac anomaly (14 patients). Patient age at the time of repair ranged from 4 days to 17 years (mean age, 5.1 +/- 4.5 years). There were no instances of intraoperative mortality or paraplegia. There were 4 deaths from 10 to 40 days postoperatively, all in neonates (mean age, 33 days) who received additional intracardiac procedures for complex associated anomalies. Follow-up has ranged from 6 months to 12.5 years (mean, 4.5 +/- 3.2 years). All children had postoperative chest roentgenograms, 80 (66%) patients have had a postoperative echocardiogram and 16 (13%) a cardiac catheterization. One patient had successful repair of a false aneurysm 4 months postoperatively. No patient has developed a late true aneurysm. Of the patients < 1 month of age at the time of CoAo repair (12 patients), 6 patients had recurrent CoAo (gradient > 20 mm Hg) compared with only 4 recurrences in 97 patients > 1 month of age at the time of repair (P < .001). CONCLUSIONS For children > 1 year of age, PTFE patch aortoplasty remains our procedure of choice for CoAo repair because of the low mortality rate, low recoarctation rate, and absence of late true aneurysms. We have stopped using this technique for infants < 1 month of age because of the high recurrence rate.

Restrictive ventricular septal defect: How small is too small to close?

Historically, indications for ventricular septal defect closure have included congestive heart failure, pulmonary hypertension, aortic insufficiency with or without aortic valve prolapse, and prior bacterial endocarditis. However, controversy exists as to how the lifetime risk of an isolated, nonoperated restrictive ventricular septal defect compares with the risk of surgical closure in an asymptomatic child. Between 1980 and 1991, cardiac catheterization and elective ventricular septal defect closure (age > 1 year, pulmonary to systemic flow ratio < 2.0) were performed in 141 patients aged 1 to 23 years (mean age, 6.1 +/- 4.7 years). Mean systolic pulmonary artery pressure was 26.9 +/- 13.0 mm Hg, and mean pulmonary to systemic flow ratio was 1.6 +/- 0.3. Aortic valve prolapse was present in 63 patients (45%), aortic insufficiency was present in 25 (18%), and 5 (3.5%) had prior bacterial endocarditis. There were no early or late deaths or major morbidity. No patient required a ventriculotomy to accomplish ventricular septal defect closure. Mean postoperative intensive care unit stay was 1.3 +/- 0.9 days, and mean hospital stay was 5.5 +/- 1.9 days. There were no instances of permanent complete atrioventricular dissociation, reoperations for bleeding, postoperative wound infections, or reoperations for residual or recurrent ventricular septal defect. These improved results justify a reevaluation of historic indications for ventricular septal defect closure.(ABSTRACT TRUNCATED AT 250 WORDS)

Expanding indications for pediatric coronary artery bypass

Pediatric coronary artery bypass has been done mostly for ischemic complications of Kawasaki disease. We reviewed our clinical experience between 1987 and 1994 with internal thoracic artery-coronary artery bypass in one infant and five children for varying indications. Indications for coronary bypass included Kawasaki disease (2), congenital left main coronary ostial stenosis, iatrogenic coronary cameral fistula, anomalous origin of the left coronary artery from the pulmonary artery, and single coronary artery traversing between the great arteries in a patient after cardiac transplantation. An additional cohort of 34 control patients of various ages and weights (1 day to 16.1 years, 2.6 kg to 62 kg) had angiographic measurements of the right coronary, left coronary, and left internal thoracic arteries with respect to the feasibility of performing coronary artery bypass. All six patients survived internal thoracic artery-left anterior descending coronary artery bypass without evidence of perioperative myocardial infarction. Postoperative angiographic studies in five and color Doppler echocardiography in one showed graft patency. Retrospective angiographic measurements in the 34 control patients showed that internal thoracic and coronary arteries are proportionately quite large in neonates and infants compared with those in older children and adolescents. Internal thoracic artery-coronary artery bypass should be considered for the expanding indications presented herein and when emergency intraoperative life-threatening situations present themselves. Long-term patency and reoperation rates have yet to be determined.

Inhaled nitric oxide for children with congenital heart disease and pulmonary hypertension.

BACKGROUND Endothelium-derived nitric oxide (NO) is a potent vasodilator and a major mediator of pulmonary vascular tone. METHODS Five infants underwent a trial of inhaled NO with hemodynamic monitoring in the operating room after atrioventricular canal repair. An additional 15 patients with congenital heart disease and refractory pulmonary hypertension were treated with inhaled NO for 1 day to 10 days postoperatively. RESULTS In the 5 infants with atrioventricular canal, corrective surgical intervention and conventional therapy (hyperventilation, inspired oxygen fraction of 0.80, and inotropic agents) lowered mean pulmonary artery pressure from 49.5 +/- 10.5 to 20.0 +/- 2.2 mm Hg (p < 0.001). Adding inhaled NO further decreased mean pulmonary artery pressure to 18.0 +/- 2.8 mm Hg (p = not significant). Inhaled NO had no effect on ventricular function curves (inflow occlusion) in this group. In the 15 patients with refractory postoperative pulmonary hypertension, 11 had a favorable response to inhaled NO, with a decrease in mean pulmonary artery pressure from 30.9 +/- 5.8 to 23.1 +/- 5.4 mm Hg (p < 0.01) in 8 patients with pulmonary artery catheters. CONCLUSIONS These studies demonstrate that inhaled NO has minimal beneficial effect on pulmonary artery pressure or cardiac output in infants after repair of atrioventricular canal. Inhaled NO is effective in decreasing PAP postoperatively in select patients with congenital heart disease and pulmonary hypertension refractory to conventional therapeutic modalities.

Role of endomyocardial biopsy in rejection surveillance after heart transplantation in neonates and children.

OBJECTIVES The aim of this study was to retrospectively evaluate the sensitivity of noninvasive surveillance (physical examination, echocardiography) of rejection in accurately predicting histologically documented rejection episodes. Additionally, the usefulness of routine scheduled biopsy and its safety in pediatric patients was explored. BACKGROUND Endomyocardial biopsy has been utilized as the standard for rejection surveillance after heart transplantation in adults, but its role in documenting clinically suspected rejection and in routine surveillance of pediatric patients has not been agreed upon. METHODS Heart transplantation was performed in 14 neonates and 21 children. The immunosuppressive regimen consisted of cyclosporine, azathioprine and prednisone. All patients underwent routine noninvasive rejection surveillance that included clinical examination and echocardiography. In the neonates, biopsy was performed quarterly beginning 6 months after transplantation, after cessation of prednisone therapy. In the children, biopsy was performed 15 times in the 1st year. A minimum of five biopsy samples were interpreted using the Working Formulation for Heart Transplant Rejection. RESULTS In the neonates, 37 biopsies were performed. Evidence of rejection was present in only three biopsy samples obtained during eight episodes (38%) of clinically suspected rejection. In 29 biopsies performed when rejection was not clinically suspected, each biopsy was free of cellular infiltrate. In the children, 291 biopsies were performed. Evidence of rejection was present in only seven biopsies (41%) from 17 episodes of clinically suspected rejection. Cellular rejection was discovered during routine rejection surveillance biopsies in asymptomatic patients in 23 (8.4%) of 274 biopsies. CONCLUSIONS In neonates with clinically suspected rejection, endomyocardial biopsy identified which patients did not require rejection therapy. Endomyocardial biopsy surveillance did not detect any unsuspected cases of rejection. In children, noninvasive rejection surveillance was less reliable even in asymptomatic patients, suggesting that periodic endomyocardial biopsy should be utilized.

Pharmacodynamics and pharmacokinetics of esmolol, a short-acting β-blocking agent, in children

SummaryEsmolol, a short-acting intravenous cardioselective β-blocking agent, was evaluated for age-dependent pharmacodynamic and pharmacokinetic features in 17 young patients (6 months to 14 years). A loading dose (500 μg/kg/min) alternating with a maintenance dose (25–200 μg/kg/min, titrating by 25 μg/kg/min every 4 min) was infused until the heart rate or mean arterial pressure decreased 10%. Cardiac index, left ventricular shortening fraction, and systemic vascular resistance were measured at baseline, peak esmolol effect, and recovery. Serum esmolol concentrations were obtained to determine the half-life and the elimination rate constant.Esmolol reduced the heart rate, blood pressure, shortening fraction, and cardiac index in all patients, but it did not change systemic vascular resistance. Maintenance esmolol dose was 118 ±49 μg/kg/min, and the half-life was 2.88±2.67 min. Blood pressure and heart rate returned to normal within 2–16 min, but cardiac index and shortening fraction took longer to recover. There were no statistically significant age-dependent pharmacodynamic effects, but blood pressure decreased prior to heart rate and cardiac index took longer to recovery in patients who weighed≤15kg. The pharmacokinetic profile in young patients was similar to that of older patients, but the half-life was shorter. The only side effeect was transient nausea and vomiting in one patient. Esmolol is a safe and efficacious β-blocking agent in young patients.

When should the hypoplastic right ventricle be used in a fontan operation? An experimental and clinical correlation☆☆☆

Eight anesthetized dogs underwent closure of the tricuspid valve and a Fontan procedure, and the right ventricular cavity was reduced in stepwise fashion. There was an increase in right atrial pressure from 9.3 +/- 2.2 to 14.1 +/- 2.4 mm Hg (p less than 0.001), a decrease in pulmonary artery pulse pressure from 10.8 +/- 2.2 to 6.8 +/- 2.2 mm Hg (p less than 0.01), and a decrease in cardiac index from 2.7 +/- 0.3 to 2.2 +/- 0.2 L/min/m2 (p less than 0.001) when the ventricular size was dropped from 50% to 25% of normal. The difference between mean pulmonary artery pressure and mean right atrial pressure, which reflects the positive stroke work index of the ventricle, disappeared once the right ventricular cavity was reduced to 25% of normal (15.0 +/- 6.1 versus 14.1 +/- 2.4 mm Hg; p = not significant). Experimental results were correlated with postoperative catheterization data from 19 patients with tricuspid atresia who had the Fontan operation. Mean right atrial pressure was 18 +/- 4.6 mm Hg and cardiac index was 2.35 +/- 0.65 L/min/m2 in patients with a direct atrium-pulmonary artery anastomosis or an atrioventricular anastomosis with a right ventricular cavity less than 30% of normal versus 13 +/- 3.2 mm Hg and 3.42 +/- 0.46 L/min/m2 for those with an atrioventricular connection and a right ventricular cavity greater than 30% of normal (p less than 0.05 and p less than 0.02, respectively). The right ventricle enlarged from 27% +/- 6% of normal preoperatively to 35% +/- 10% of normal on follow-up (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and electrophysiologic features of fetal and neonatal paroxysmal atrial tachycardia resulting in congestive heart failure

Those clinical and electrophysiologic features of paroxysmal atrial tachycardia (PAT) that appeared to be the cause of prenatal congestive heart failure (CHF) (hydrops fetalis) were evaluated in 12 neonates, ages 1 to 14 days, and compared with those occurring in 12 neonates, ages 2 to 34 days, who developed CHF from PAT diagnosed postnatally. Transesophageal electrophysiologic evaluation was performed after birth or at the time of PAT occurrence in the prenatal CHF group and at the time of CHF diagnosis in the postnatal CHF group. Before the electrophysiologic study, spontaneous PAT onset and termination were observed in all prenatal CHF neonates. In the postnatal CHF neonates, however, a single, prolonged episode of PAT was observed. During PAT, all neonates were observed to have a regular heart rate, normal QRS morphology and ventriculoatrial interval exceeding 80 ms. These findings suggested an orthodromic reciprocating tachycardia using an accessory atrioventricular connection as the tachycardia mechanism. In the 12 neonates with prenatal CHF, the PAT cycle length measured 243 +/- 30 ms, whereas in the 12 neonates with postnatal CHF it measured 208 +/- 19 ms (p less than 0.003). Neonates with prenatal CHF secondary to PAT appear to develop CHF from multiple PATs recurring at relatively long cycle lengths (slow heart rates), whereas postnatal CHF neonates develop heart failure symptoms during a sustained tachycardia episode with relatively short cycle lengths (fast heart rates).

Failure of the Hemashield extension in right ventricle-to-pulmonary artery conduits

Between 1989 and 1991, 17 children underwent 18 right ventricle-to-pulmonary artery conduit placement operations using a composite of an aortic or pulmonary valved homograft and a Hemashield extension to the ventricle. Hemashield is a collagen-coated knitted Dacron graft with excellent compliance and hemostatic properties. Diagnoses included tetralogy of Fallot with pulmonary atresia (7), truncus arteriosus (6), and complex transposition of the great arteries (4). Mean age at conduit placement was 4.9 +/- 4.2 years, and all patients survived. At a mean follow-up of 14 +/- 4 months, postoperative Doppler echocardiographic gradients between the ventricle and pulmonary artery ranged from less than 20 to 60 mm Hg. At cardiac catheterization 13 +/- 3 months postoperatively (6 patients), the systolic pressure gradient across the conduits ranged from 14 to 90 mm Hg (mean gradient, 59 +/- 29 mm Hg). Conduit obstruction, when present, was demonstrated angiographically to be in the Hemashield portion and led to early conduit replacement six times in 5 patients (33% of operations) within 10 to 18 months (mean time, 14 months) after insertion of the original conduit. Pathologic examination of the explanted conduits revealed the obstruction to be a thick neointimal peel that was impossible to separate from the Hemashield graft. Failure of the Hemashield as an extension for ventricle-to-pulmonary artery conduits secondary to accelerated neointimal formation has led us to abandon its use in clinical practice.

Massive primary chylopericardium: a case report.

A large pericardial effusion was discovered in an asymptomatic 12-year-old boy admitted for an elective orthopedic procedure. On physical examination, heart rate was 96 and blood pressure was 130/70 without paradox. The neck veins were not distended, but heart tones were distant. Chest roentgenogram (CXR) showed an enlarged cardiac silhouette. Echocardiogram showed a massive pericardial effusion compressing the right atrium, with depressed ventricular contractility. Pericardiocentesis yielded 450 mL of chylous fluid. A percutaneous pericardial drain was placed and drained another 400 mL of chyle. Pericardial fluid reaccumulated even though the patient was on a low-fat diet, and 1 week after admission left thoracotomy was performed with partial pericardiectomy and pericardial window. There was 1 L of chyle in the pericardial sac; frozen section of the pericardium showed lymphangiectasia. Chest tube drainage diminished rapidly and the patient was discharged. Follow-up CXR at 1 week showed fluid in both pleural spaces requiring bilateral tube thoracostomies again draining chyle. Even with total parenteral nutrition (TPN), 500 mL/d of chyle drained from the pleural tubes. Right thoracotomy with ligation of the thoracic duct was performed after 1 week of TPN. Pleural drainage abruptly dropped, and there has been no reaccumulation in either the pleural spaces or pericardium at 6-month follow-up. This case dramatically supports early thoracic duct ligation and partial pericardiectomy as the treatment of choice for primary massive chylopericardium.