Imperial Ballroom

30. The Hemodynamic Importance of Atrial Contraction After Right Ventriculotomy

ROBERT A. GUYTON*, MICHAEL J. ANDREWS*,

LAWRENCE L. MICHAELIS* and ANDREW G. MORROW, Bethesda, Maryland

Clinical observation of the hemodynamic effects of various arrhythmias led to the hypothesis that patients with impaired right ventricular function are unusually vulnerable to the loss of an appropriately timed atrial contraction. In 6 acute canine preparations, effective atrial contraction was abolished by simultaneous atrial and ventricular (AV) pacing. At constant cardiac output, aortic pressure, and heart rate only a small rise (1.4 mm. Hg) in mean right atrial (RA) pressure was observed before a vertical right ventriculotomy; a much larger (p <.01) rise (9.5 mm. Hg) occurred after ventriculotomy. Right heart failure with visible and palpable tricuspid regurgitation was induced after ventriculotomy by volume overload and AV pacing. Restoration of atrial contraction (sequential AV pacing) eliminated the visible regurgitation, lowered the average mean RA pressure from 22.2 to 3.9 mm. Hg, p <.001, and led to a rise in average cardiac output from 2.6 to 2.8 L/min., p< .05. After right ventriculotomy, and at a constant RA pressure, aortic pressure, and heart rate, loss of atrial contraction resulted in a 42% reduction in cardiac output.

Eight patients who had had right ventriculotomies were studied in the early postoperative period. Abolition of effective atrial contraction by AV pacing caused an average reduction in cardiac output of 22%. In contrast, cardiac output fell only 5% in five other patients when AV pacing was instituted after aortic valve replacement (p <.01).

Loss of atrial contraction may have little deleterious effect on the function of the normal right heart, but in patients in whom the contractility and compliance of the right ventricle have been impaired by operation, restoration of effective atrial contraction by atrial pacing or sequential atrioventricular pacing may be of important clinical benefit.

*By invitation

31. Right Ventricular Outflow Tract Reconstruction with a Valved Conduit in 75 Cases of Congenital Heart Disease

CHARLES H. MOORE*, VALENTINO MARTELLI* and

DONALD N. ROSS*, London, England

Sponsored by John Derrick, Galveston, Texas

Reconstruction of the right ventricular outflow tract using an aortic homo-graft conduit was performed in 75 patients at the National Heart Hospital, London, from 1966 to 1974. The age range was 2 to 47 years and the types of congenital heart disease were as follows: - pulmonary atresia (35), severe tetralogy of Fallot (22), truncus arteriosus (6), transposition of great arteries (3), single ventricle (2), and tricuspid atresia (7). An early mortality of 48% has been relatively high in this most difficult group of patients: pulmonary atresia (60%), tetralogy of Fallot (32%), truncus (50%), transposition of great arteries (33%), single ventricle (100%), and tricuspid atresia (43%). Ninety percent of the cases had one or more previous shunt operations and this is a factor influencing mortality. Other factors affecting mortality include age, pulmonary vascular resistance, the surgical anatomy and surgical technical problems including bleeding, prolonged bypass, coronary artery injury and compression of the conduit by the sternum. Increased experience with the complex operative techniques should minimize surgical mortality.

Late follow-up has included a low mortality of 2.7% and good to excellent clinical results in survivors. Although calcification occurs early in the wall of the homograft, valve function has been excellent in cases followed-up to 8 years. Improved methods of homograft preparation and preservation are responsible for the continued good function of the conduit.

Our present approach in these cases is to avoid shunts, particularly aorto-pulmonary anastomoses, define the anatomy precisely with biplane still-film angiography, and to undergo total correction when severe hypoxia or effort intolerance occurs, or before increased pulmonary vascular resistance develops.

*By invitation

32. Type C Complete Atrioventricular Canal: Surgical Considerations

NOEL L. MILLS*, JOHN L. OCHSNER, TERRY D. KING*,

New Orleans, Louisiana

Eight patients with Type C A-V canal have had surgical correction at the Ochsner Clinic in the past two years. Ages range from 16 months to nine years. There were no early or late deaths. Mapping of the conduction system proved invaluable and a transient heart block occurred in only one patient. Technical guidelines are presented for a standard operation. Prior to bypass, accurate palpation of the level that the anterior common leaflet ascends and the arch that it inscribes is necessary. The major area of canal closure is allocated to the ventricular portion. Precise marking and splitting of the valve leaflets, correct reattachment of leaflets to thin, pliable patch material, and suture of the mitral cleft by % of the distance from the septal margin to the cordal attachments are mandatory. Small interrupted felt buttressed sutures avoid disruption. At recatheterization, mitral incompetence improved from III-IV/VI to 0-II/VI, and there were no residual shunts. It has been suggested the Type C A-V canal is more difficult to repair and valve replacement is often necessary. However, since we have used the present technique of reconstruction, we have achieved consistent and reliable good results without prosthetic valves.

*By invitation

33. A New Surgical Approach for Correction of Partial Anomalous Pulmonary Venous Drainage into the Superior Vena Cava

CLAUDE CHARTRAND*, MAURICE PAYOT*,

ANDRE DAVIGNON* and PAUL STANLEY*, Montreal, Canada

Sponsored by Jacques Bruneau, Montreal, Canada

Corrective techniques for partial anomalous pulmonary venous drainage into the superior vena cava have not been adequate up to the present time; a high rate of occlusion and narrowing of the vena cava or of the pulmonary veins in addition to residual shunts have been reported in follow up studies. Nine patients aged from four to nine years had anomalous right pulmonary veins draining into the superior vena cava. Eight had an associated atrial septal defect. In two cases, a left superior vena cava was present and the right superior vena cava was small. The same surgical technique was used for all patients and consisted essentially of partitioning and enlargement of the superior vena cava. The partitioning was done in all, but in one, with a longitudinal suture starting above the highest pulmonary vein redirecting the pulmonary venous flow through the atrial septal defect into the left atrium. The anterior cavo-auricular tunnel was then enlarged by a right atrial appendage to superior vena cava angioplasty. The surgical technique will be described in detail. Follow up studies were done between fourteen and twenty-eight months (average 21) after surgery included clinical examination, ECG, X-Ray, hemodynamic and angiographic evaluation. Clinically, all patients were asymptomatic. On the angiograrns, no occlusion of the superior vena cava or of the pulmonary vessels were noted. A 25% narrowing of the superior vena cava was detected in one patient and was accompanied by a 6 mm of Hg gradient at the site of the partial stenosis; in this case, there was a left superior vena cava and the right superior vena cava was small. In another case a 4 mm anomalous pulmonary vein draining too high into the superior vena cava was left untouched. This patient has a residual left to right shunt of 11%. In all other patients, hemodynamic and angiographic data demonstrated good correction. These results are encouraging and indicate that this new technique for correction of partial anomalous pulmonary venous return into the superior vena cava is superior to those which have previously been reported by others as well as by our group.

INTERMISSION - VISIT EXHIBITS (Albert Hall)

*By invitation

34. Management of Severe Aortic Coarctation and Interrupted Aortic Arch in Neonates

MERRILL H. BRONSTEIN*, NOEL H. FISHMAN, BENSON B. ROE,

L. HENRY EDMUNDS, JR. and ABRAHAM M. RUDOLPH*,

San Francisco, California

The medical and surgical treatment of aortic coarctation and interrupted aortic arch in the neonatal period and early infancy has been previously associated with a high mortality rate (40-60%).

Thirty-seven infants, age range 2-42 days, with severe aortic arch obstructive lesions underwent emergency surgery between 1966 and 1974. Indications for catheterization and operation were abrupt onset of severe congestive heart failure and acidemia usually secondary to spontaneous closure of the ductus arteriosus which constricted blood flow to the lower body.

Resection of coarctation with end-to-end anastomosis was performed in 25 patients. Death in 7 (28%) was related to technical problems (2), postoperative complications (3), or associated lesions (2). Recoarctation developed in 3. Since 1969, the operative mortality has been reduced to 13% (2/15).

Twelve infants underwent various surgical procedures for interrupted aortic arch, 8 Type I and 4 Type II. All had large VSD's; associated pulmonary artery banding was performed in 10. Severe additional intracardiac anomalies were present in 5. Seven patients (5 Type I, 2 Type II) survived.

Two infants with interrupted aortic arch were treated by surgical techniques previously undescribed. In one, a long tubular hypoplastic isthmus was restored to normal caliber using the incised subclavian artery as a pedicle patch; in the second, with Type II interruption, continuity of flow was restored by end-to-end anastomosis between the left common carotid artery and descending aorta. The patient's VSD was successfully closed on cardiopulmonary bypass at 6 months.

*By invitation

35. Ascending Aorta to Right Pulmonary Artery Shunt: Experience With 80 Patients

CHARLES A. CAVALLO*, F. S. IDRISS, R. KOOPOT*,

H. NIKAIDOH* and MILTON H. PAUL*, Chicago, Illinois

Ascending aorta to right pulmonary artery shunt (Waterston-Cooley) has been successfully used to increase pulmonary artery flow in different types of congenital heart disease. In order to assess the specific technical and hemodynamic problems inherent to this procedure we reviewed our experience in 80 patients. Their ages ranged from 1 day to 13 years. Forty-nine patients had tetralogy of Fallot, 13 transposition of the great vessels with pulmonary stenosis, 5 tricuspid atresia, 11 isolated pulmonary atresia, 1 Ebstem anomaly with pulmonary stenosis, and 1 A-V canal with pulmonary stenosis. In 27 patients the shunt procedure was performed using an approach posterior to the superior vena cava (Waterston) while in 50 patients the approach was anterior to the superior vena cava (Cooley). Three patients with a previously established shunt were referred for complete repair. The overall hospital mortality was 18%, 12 of the 14 deaths occurring in infants younger than 6 months of age. The majority of patients had varying degrees of differential blood flow between the right and left pulmonary artery noted on the chest roentgenogram with no remarkable difference between the two techniques. Ten patients have undergone subsequent takedown of the shunt with intracardiac repair. There was no hospital or late mortality in this group. In two patients the shunt was closed through the aorta while in the remaining 8 the right pulmonary artery was detached from the aorta at the shunt site in order to repair the pulmonary artery with an artenoplasty or enlarge it with a pericardial patch. In this study we found that in addition to the inherent hemodynamic problem of a left to right shunt, the ascending aorta to right pulmonary artery shunt causes distortion of the right pulmonary artery, producing a differential pulmonary flow regardless of the type of approach, and necessitating detaching the pulmonary artery from the aorta in order to accomplish a satisfactory repair. Because of these various difficulties, we would recommend that primary repair be performed whenever possible rather than this palliative shunt followed by later correction.

*By invitation