Richard N. Gates

Early and late results of mitral valve repair in children

Mitral valve repair in children has the advantage of avoiding mitral valve replacement with its attendant need for anticoagulation and reoperation. Seventy-nine children between the ages of 2 months and 17 years (mean 4.9 years) underwent mitral valve repair between May 1982 and April 1993. There were five patients with mitral stenosis and 74 patients with mitral regurgitation, and 19 children were less than 2 years of age. Patients were divided into anatomic subgroups on the basis of the primary cardiac pathologic condition. Forty-three had severe mitral regurgitation, 21 had moderate mitral regurgitation, and 12 patients with primum atrial-septal defect and 2 patients with univentricular hearts had minimal to moderate mitral regurgitation. Associated cardiac anomalies were present in 68 patients and 85% of the patients required concomitant intracardiac procedures. The methods of mitral valve repair included annuloplasty in 68 (86%), repair of cleft leaflet in 41 (52%), chordal shortening in 9 (11%), triangular leaflet resection in 8 (10%), splitting of papillary muscles with resection of subvalvular apparatus in 7 (9%), and chordal substitution in 1 (1%). The technique of annuloplasty was modified to allow for annular growth. Follow-up was available from 1 to 10 years (mean 4 +/- 2.5 years). There were three early deaths (4%), all occurring as a result of low output cardiac failure in patients with minimal postoperative mitral regurgitation. Three late deaths (4%) occurred in patients with persistent moderate to severe mitral regurgitation and progressive cardiac failure and eight patients (10%) required either rerepair or replacement of the mitral valve. Actuarial survival was 94% at 1 year, 84% at 2 years, and 82% at 5 years, and actuarial freedom from reoperation was 89% at 8 years. All patients received postoperative echocardiography with 82% having minimal to no mitral regurgitation and 98% of long-term surviving patients being free of symptoms. We conclude that mitral valve repair can be done with low early and late mortality. The need for reoperation is relatively low and valve growth has occurred with the use of a modified annuloplasty.

Gross and microvascular distribution of retrograde cardioplegia in explanted human hearts

In this report, explanted hearts from transplant recipients with the diagnosis of idiopathic cardiomyopathy underwent a blood cardioplegia arrest and extended subatrial resection to preserve their coronary sinus venous system. The coronary sinus and left and right coronary arteries were then cannulated and warm blood cardioplegia retrograde infused at a pressure of 30 to 40 mm Hg. Effluent from the coronary arteries and thebesian veins was then collected. Hearts were subsequently fixed with retrograde glutaraldehyde perfusion and perfused retrograde with NTB-2 (an inert intracapillary marker). Histologic sections were examined from 12 separate sites. There was no significant difference in the percentage of capillaries perfused by retrograde-delivered cardioplegia between corresponding regions of the left and right ventricles. However, effluent analysis indicated that 67.2% +/- 6.4% of retrograde-delivered blood cardioplegia was shunted through thebesian veins, thereby bypassing the microvasculature, whereas 29.3% +/- 6.3% and 3.5% +/- 3.1% traversed the myocardium supplied by the left and right coronary arteries, respectively. The results indicate that all regions of both ventricles are perfused by retrograde blood cardioplegia. However, they also suggest that nutrient flow to the microvasculature of the right ventricle is minimal during retrograde cardioplegia.

The Fontan Procedure in Adults

BACKGROUND A retrospective clinical study was performed to document the course of adult patients undergoing the Fontan procedure. METHODS Between 1982 and 1994, 21 adults aged 18 to 40 years (mean age, 27 +/- 7 years) underwent a Fontan procedure. Anatomic diagnosis was tricuspid atresia in 9, double-inlet left ventricle in 4, and various single ventricles in 8. Four underwent a right atria-right ventricle connection, 13 had a right atria-pulmonary artery connection, and 4 had a lateral-tunnel Fontan. Three of these 4 had a snare-adjustable atrial septal defect. Preoperative risk factors assessed were left ventricular end-diastolic pressure greater than 10 mm Hg, ejection fraction lower than 0.45, mean pulmonary artery pressure higher than 15 mm Hg, transpulmonary gradient greater than 10 mm Hg, pulmonary artery abnormalities, and atrioventricular valve regurgitation. Mean preoperative risk score was 1.6 /-1.1. Mean New York Heart Association class was 2.6 +/- 0.5. RESULTS The operative mortality rate was 5% (1/21). Six patients (30%) had a major complication, four being prolonged effusions. One patient was lost to follow-up; the remaining 20 have been followed for a mean of 7.4 +/- 3.8 years. At follow-up, mean New York Heart Association class was 1.7 +/- 0.5. There has been one late death (5%) at 9 2/3 years, which was probably due to ventricular arrhythmia. Three patients (16%) have required and survived reoperation. During follow-up, 7 patients (37%) have had development of atrial arrhythmias requiring medication, and 2 have been treated for ventricular arrhythmias. CONCLUSIONS These results indicate that properly selected adults can undergo the Fontan procedure with low morbidity and mortality. However, late-developing arrhythmias, need for reoperation, and decreasing ventricular function are serious problems that mandate careful follow-up.

Coronary sinus ostial occlusion during retrograde delivery of cardioplegic solution significantly improves cardioplegic distribution and efficacy.

UNLABELLED This study documents the gross flow characteristics and capillary distribution of cardioplegic solution delivered retrogradely with the coronary sinus open versus closed. METHODS Five explanted human hearts from transplant recipients were used as experimental models. Hearts served as their own controls and received two doses of warm blood cardioplegic solution, each containing colored microspheres. The first dose was delivered through a retroperfusion catheter with the coronary sinus open and the second dose was delivered with the sinus occluded. Capillary flow was measured at twelve ventricular sites and gross flow was measured by examining coronary sinus regurgitation, thebesian vein drainage, and aortic effluent (nutrient flow). RESULTS Coronary sinus ostial occlusion allowed for a significant decrease in total cardioplegic flow (1.74 +/- 0.40 ml/gm versus 1.06 +/- 0.32 ml/gm; p < 0.05) to occur while maintaining an identical intracoronary sinus pressure. Ostial occlusion also resulted in an increase in the ratio of nutrient flow/total cardioplegic flow from 32.3% +/- 15.1% to 61.3% +/- 7.9% (p < 0.05). A statistically significant improvement in capillary flow was found at the midventricular level in the posterior intraventricular septum and posterolateral right ventricular free wall. This improvement was also documented for the intraventricular septum and right ventricle at the level of the apex. CONCLUSION Coronary sinus occlusion during retrograde cardioplegia significantly improves cardioplegic delivery to the right ventricle and posterior intraventricular septum. Furthermore, the technique affords a significant improvement in nutrient cardioplegic flow while reducing the overall volume of cardioplegic solution administered.

Damus-Stansel-Kaye procedure: Current indications and results

Between October 1983 and August 1991, 29 consecutive Damus-Stansel-Kaye procedures were performed. Indications for operation included restrictive bulboventricular foramen or subaortic stenosis associated with complex univentricular congenital heart disease (25) and Taussig-Bing heart, subaortic stenosis, or both associated with complex biventricular congenital heart disease (4). Twelve patients underwent concurrent Fontan procedures. Average age at operation was 39.8 months (range, 1 to 132 months). Average outflow tract gradient was 28 mm Hg (range, dynamic to 80 mm Hg). Of the 29 patients, 23 were male and 6 were female. There were three early deaths (10%), two in patients who had a concurrent Fontan procedure. Although there was a trend toward lower age and higher outflow tract gradients in nonsurvivors, these and other factors were not statistically significant predictors of death. Actuarial freedom from cardiac-related death was 88% at 5 years (n = 7). In a mean follow-up of 3.5 years (range, 0.1 to 7.7 years), 3 patients have required reoperation (10%), 2 for aortic valve insufficiency (5 days and 2.75 years) and 1 for a gradient across the anastomosis (5.75 years). Actuarial freedom from reoperation related to a failed Damus-Stansel-Kaye procedure was 90% at 4 years and 75% at 6 years (n = 7).

Ventricular effluent of retrograde cardioplegia in human hearts has traversed capillary beds

BACKGROUND In human hearts, as much as two thirds of retrograde cardioplegia is shunted through thebesian and arteriosinusoidal channels into the ventricular cavities. This ventricular effluent is believed to have bypassed the myocardial capillary beds and is therefore considered nonnutritive. METHODS To test this hypothesis, we studied the explanted hearts from 9 cardiac transplant recipients with the diagnosis of idiopathic cardiomyopathy. These hearts were arrested in situ with cold blood cardioplegia and excised with the coronary sinus intact. The left and right coronary ostia and the coronary sinus then were cannulated. Colored microspheres (15 +/- 5 microns) mixed in 37 degrees C blood cardioplegia were administered through the coronary sinus at a pressure of 30 to 40 mm Hg. Effluents from the coronary arteries and ventricular chambers were collected and analyzed for microsphere concentration. RESULTS Approximately 80% of retrograde cardioplegia solution was recovered in the ventricular chambers. Nearly 40% of this ventricular chambers effluent had traversed capillary beds and, thus, we believe has nutritive properties. Almost all of the coronary artery effluent of retrograde cardioplegia solution had traversed capillary beds. The total nutritive fraction of retrograde warm blood cardioplegia in this explanted human heart model was approximately 55%. CONCLUSIONS These findings suggest that the ventricular chamber effluent of retrograde blood cardioplegia contributes to the metabolic homeostasis of the arrested human heart.

Aortic to right ventricular shunt for pulmonary atresia and intact ventricular septum.

Acute or chronic myocardial ischemia may develop in patients with pulmonary atresia with intact ventricular septum and right ventricular-dependent coronary circulation. In such cases an aorta to right ventricle shunt may be used to reverse this ischemia. This report summarizes our experience with the placement of an aortic to right ventricular shunt in 5 patients. The shunts were made of Gore-Tex and ranged from 4 mm to 8 mm. Associated procedures were bidirectional Glenn (n = 2) and Fontan (n = 2). All 5 patients survived the procedure with documented early graft patency and no evidence of ischemia.

The regional capillary distribution of retrograde blood cardioplegia in explanted human hearts

Warm retrograde blood cardioplegia is frequently used for myocardial protection, despite experimental studies questioning the adequacy of capillary flow to the right ventricle and septum. The capillary distribution of retrograde blood cardioplegia in the human heart is unknown. Hearts from eight transplant recipients with the diagnosis of idiopathic or dilated cardiomyopathy were arrested in situ with cold blood cardioplegia and excised with the coronary sinus intact. Within 20 minutes of explanation, colored microspheres mixed in 37 degrees C blood cardioplegia were administered through the coronary sinus at a pressure of 30 to 40 mm Hg for 2 minutes. Twelve transmural myocardial samples were taken horizontally at the level of midventricle and apex to determine regional capillary flow rates. When retrograde warm blood cardioplegia was administered at a rate of 0.42 +/- 0.06 ml/gm/min, the left ventricle, the septum, the posterior wall of the right ventricle, and the apex consistently received capillary flow rates in excess of their metabolic requirements. The capillary perfusion of anterior and lateral walls of the right ventricle was marginally adequate to sustain aerobic metabolism. In explanted human hearts, retrograde blood cardioplegia provides adequate capillary flow to the left ventricle, the septum, the posterior wall of the right ventricle, and the apex; however, capillary flow to the anterior and lateral walls of the right ventricle is marginal. This study delineates the tenuous balance between supply and demand for right ventricular protection with warm continuous retrograde blood cardioplegia.

Side-to-Side Aorto–Gore-Tex Central Shunt

BACKGROUND This report details our experience in 13 patients with a technical modification of the standard central shunt. METHODS The study was performed using a retrospective chart review approach. In our operation, the aorto-Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) anastomosis is created in a side-to-side fashion with the free end of the Gore-Tex shunt being oversewn. RESULTS All patients had echocardiographic evidence of shunt patency in the immediate postoperative period, and there have been no cases of late shunt occlusion at a mean follow-up period of 10 months. CONCLUSIONS We believe this approach will yield patency rates equivalent to or better than those of the standard central shunt. The technique has the advantage of creating a short, straight-lying shunt that is less likely to kink or be injured on repeated sternotomy and in which flow may be more reliable.

Damus-Stansel-Kaye procedure: Technical modifications

The Damus-Stansel-Kaye procedure has been applied for the relief of outflow tract obstruction caused by a restrictive bulboventricular foramen or subaortic stenosis in patients with complex univentricular heart disease. The procedure may also be part of a biventricular repair of a Taussig-Bing transposition of the great arteries. This report details technical modifications of the procedure to ensure unobstructed blood flow from the pulmonary artery to the aorta and to maintain the integrity of the pulmonary and aortic valves.