Paul A. Ebert

Pulmonary Valve Replacement for Regurgitation after Repair of Tetralogy of Fallot

In general, it has been thought that pulmonary valve insufficiency is well tolerated when the valve is excised or when the pulmonary annulus has been widened with an outflow patch during repair of tetralogy of Fallot. However, when pulmonary regurgitation is massive or when it is combined with other causes of right ventricular failure, progressive right ventricular dilation may occur in some patients. Pulmonary valve replacement has not been commonly used in the past. From January, 1980, to August, 1982, 12 patients, 11 months to 17 years old, had pulmonary regurgitation treated by insertion of a valve in the pulmonary position 4 1/2 months to 11 years after initial repair of tetralogy of Fallot. All patients had progressive right ventricular failure not responsive to medical management. There were no major outflow tract obstructions, residual ventricular septal defects, or persistent aortopulmonary shunts. All 12 patients underwent patch reconstruction of the right ventricular outflow tract that allowed placement of a larger valve. There have been no operative or late deaths, and each patient has had improvement in functional status. One patient required tricuspid valve replacement 1 1/2 years after pulmonary valve replacement to achieve sustained relief of symptoms. Only 1 other patient required subsequent operation; this was for pacemaker lead changes. These early results suggest that in patients with right ventricular failure, attention should be directed to pulmonary regurgitation since this is a component of failure that is reversible; pulmonary valve replacement carries a low risk, and it can relieve symptoms and prevent further deterioration of right ventricular function.

Second operations for pulmonary stenosis or insufficiency after repair of tetralogy of fallot

Twenty-four patients with previous surgery for repair of tetralogy of Fallot were in need of subsequent operative procedures for either residual pulmonary stenosis or pulmonary valve incompetence. The second operation was performed 1 to 21 years after the initial repair. The patients with pulmonary valve incompetence had evidence of marked right ventricular dysfunction and required pulmonary valve replacement. The patients with residual pulmonary stenosis had modifications of their pulmonary outflow tract to reduce the gradient. Five of the 15 patients with stenosis required pulmonary valve replacement. Clinical improvement has been good, but objective reversal of right ventricular dysfunction has been difficult to document.

Preliminary Experience with Aspirin for Anticoagulation in Children with Prosthetic Cardiac Valves

Twenty-four children (ages 1 to 18 years, mean 12.2 years) underwent 27 operations for aortic, mitral, or combined aortic and mitral valve replacement. There was 1 operative death. Of the 23 operative survivors (12 aortic, 8 mitral, 3 combined valve replacement), only 5 were given warfarin for long-term anticoagulation. The remaining 18 (10 aortic, 8 mitral valve replacement) were given aspirin (plus dipyridamole in 5). Twelve of the 18 had at least one mechanical valve (11 Björk-Shiley and Beall valves; 1 Björk-Shiley valve was replaced with a Beall disc valve as the child grew). These 18 patients were followed for 1 to 59 months (mean, 20.4 months). There was no thrombotic, embolic, or bleeding complications. There were 2 late deaths (one cardiac). Review of the available literature indicates that in children with prosthetic cardiac valves, aspirin (with or without dipyridamole) provides adequate protection against thromboemboli and avoids the hemorrhagic complications associated with warfarin.

Advantages of Potassium Cardioplegia and Perfusion Hypothermia in Left Ventricular Hypertrophy

An attempt was made to determine the effect of hypothermic potassium cardioplegia (35 mEq of potassium chloride) on the hypertrophic ventricle. Puppies with induced left ventricular hypertrophy were divided into four groups and studied after one hour on global ischemia. Myocardial adenosine triphosphate (ATP) was best preserved in the hypothermically perfused groups and correlated well with measurements of coronary sinus creatine phosphokinase (CPK). In Groups 1 and 2 (anoxic arrest at 37 degrees C and KC1 perfusion at 37 degrees C), CPK at 30 minutes of reperfusion was 1,031 and 198 IU, respectively, compared to 35 IU in Group 3 (KC1 perfusion at 4 degrees C) and 44 IU in Group 4 (Ringers lactate at 4 degrees C). Myocardial injury was milder in Groups 3 and 4 regardless of whether potassium chloride was added. It is apparent that hypothermic perfusion of a hypertrophic ventricle was the major factor in myocardial preservation, as determined by myocardial ATP and coronary sinus CPK.

Infant Coarctation: A Spectrum in Clinical Presentation and Treatment

Between 1975 and 1985, 125 infants 2 to 365 days old (majority, 30 days old or less) with coarctation of the aorta underwent surgical repair. Forty-seven patients (38%) had severe congestive heart failure (CHF), metabolic acidosis, and poor systemic perfusion. The predominant operative technique was synthetic patch aortoplasty (100 patients); the remaining 25 had an end-to-end anastomosis. There were no operative deaths. Perioperative complications were minimized with the synthetic patch technique (less than 15%). For patients surviving at least 3 months after repair, the arm-leg systolic blood pressure gradient was relieved in 82% (71/87) of the patients having patch aortoplasty versus 65% (15/23) of the patients with end-to-end anastomosis. Although the rate of reoperation between the two groups was similar (patch, 5 [6%]; end-to-end, 3 [13%], two of the reoperations in the patch group were for preexisting hypoplastic transverse aortic arch. Late deaths (20 patients, 16%) were due to other major associated cardiac anomalies. Patch aneurysms have not occurred. Expedient use of synthetic patch aortoplasty has decreased perioperative complications, relieved coarctation gradients for CHF, increased early survival even in the presence of complex or associated cardiac anomalies, and has an acceptable rate of recurrent coarctation (6 to 13%).

Evaluation of early postoperative coronary artery bypass graft patency by contrast-enhanced computed tomography

Fifty patients with 117 coronary bypass grafts were studied by contrast-enhanced computed tomography at an average of 5 +/- 4 days after surgery to determine if this technique was a feasible method for detecting early postoperative graft occlusion. The study was limited in only three patients because of incisional chest pain (one patient) or multiple metal clips attached to the graft (two patients). The distal patency of sequential grafts cannot be determined by current techniques. There was a lower graft patency rate (70%) in the 10 patients with perioperative myocardial infarction than in the 40 (95%) without (p less than 0.025), but most regions of infarcted myocardium were perfused by patent grafts. There were eight graft occlusions in eight patients. The graft occlusion rate (30%) was significantly higher (p less than 0.025) in grafts with intraoperative flows less than 45 ml/min. The postoperative complications of myocardial dysfunction, arrhythmia and coronary artery spasm did not correlate with graft occlusion. Early graft occlusion is uncommon (7%) and usually occurs in grafts with low flows or severe distal disease (seven of eight grafts), or both. Thus, the need for early reoperation is very infrequent. It is concluded that contrast-enhanced computed tomography is feasible for the assessment of coronary bypass graft patency. Because early graft occlusion is unusual the technique may be an ideal noninvasive screening method.

Intrauterine Cardiothoracic Surgery: The Fetal Lamb Model

We have developed fetal lamb models of congenital cardiothoracic lesions that have been allowed to progress through birth for physiological study. Simulated lesions, simulated repairs, actual lesions, and actual repairs have been performed in this model. Sixty-two fetal lambs comprised the study group, including 48 in which models were created and 14 controls. Models included pulmonary stenosis, aortic stenosis, and diaphragmatic hernia. Gestational age ranged from 90 to 120 days (0.6 of normal gestation). In each pregnant ewe, laparotomy and hysterotomy were performed under general anesthesia, with care taken to avoid placental vessels. The foreleg was exposed, the appropriate anterior chest wall was isolated, and a thoracotomy was done. Thoracic or cardiac procedures then were performed under controlled transplacental anesthesia and perfusion. Following completion of the procedure, the fetal thoracotomy was closed, sterile antibiotic solution was placed in the amniotic sac, and the hysterotomy and laparotomy were closed. Subsequently the fetus either was allowed to progress to birth and infant study or underwent subsequent intrauterine repair and then was allowed to progress to birth and neonatal study. This fetal lamb model provides reproducible anatomical and pathophysiological lesions to facilitate the development of techniques for repair of such lesions in early infancy. Further, it offers the potential for developing methods of intrauterine cardiothoracic surgical repair.

Indications and Techniques for Midline Approach to Aortic Coarctation in Infants and Children

A variety of techniques have been described for the repair of aortic coarctation. Most of these use operative exposure through a left thoracotomy. There are, however, instances when a median sternotomy provides a more versatile approach and allows for equally acceptable repair. Twelve patients (age, 2 days to 16 years) with coarctation of the aorta serve to illustrate the value of the technique. All but 3 patients were under 3 years old. Five patients had repair of coarctation combined with repair of other congenital cardiac anomalies (atrial and ventricular septal defects, 2 patients; atrial septal defects, 2 patients; and valvular aortic stenosis, 1 patient). Six patients had complicated recurrences of previously repaired coarctations and 1 patient had a primary coarctation that involved the aortic arch. All repairs were accomplished through a median sternotomy with the use of cardiopulmonary bypass and periods of (1) total circulatory arrest (6 patients); (2) reduced flow (4 patients); or (3) normal flow with multiple sites of arterial inflow (2 patients). All patients did well with no operative mortalities and no sequelae to date (8 weeks to 4 years). Examples of various techniques are provided to demonstrate the flexibility obtainable with this method. Median sternotomy can provide a viable approach to difficult problems involving coarctation of the aorta.

Operative correction of total left anomalous pulmonary venous return.

The evaluation, surgical repair, and follow-up are described in an asymptomatic 27-year-old man with unilateral total anomalous pulmonary venous return from the left lung through an innominate vein and a patent foramen ovale. The anomalous vein was divided and anastomosed directly to the left atrium using a vascular technique that produced an orifice larger than the vein diameter. Radionuclide scanning accurately identified the anomaly before operation and allows periodic noninvasive reevaluation after operation. Correction is recommended in all patients with unilateral anomalous pulmonary venous return because disease in the one normal lung could be fatal.

Aortic allografts: Reconstruction of right ventricle-pulmonary artery continuity

The use of aortic allografts in the repair of congenital cardiac lesions has increased as a result of both the advent of cryopreservation and the effects of increased donor availability secondary to infant transplantation. During the period 1986 through 1987, 38 cryopreserved aortic allografts were placed for right ventricle-pulmonary artery discontinuity. Size of the allografts ranged from 11 to 26 mm (mean size, 19 mm), and age of the patients ranged from 6 weeks to 26 years (mean age, 5 years). Twenty-one patients had primary placement of aortic allografts, and 17 underwent replacement of previous conduits. There were 5 hospital deaths (13%) overall, only 1 among the 10 patients younger than 6 months of age with truncus arteriosus, and none among the 17 patients having conduit replacement. A large conduit could be placed with a low incidence (10.5%) of postoperative hemorrhage related to the conduit. The aortic allograft is our conduit of choice for both conduit replacement and primary repair of right ventricle-pulmonary artery discontinuity.