Kirklin, John W.

A total of 131 patients with the partial form of common atrioventricular canal were operated on between March, 1955 and January, 1964. The over-all hospital mortality rate was 3.8%; no deaths occurred in patients who had no or only mild incompetence of the mitral valve. Permanent heart block has not occurred in the last 93 cases. Results have been good in general, although there is evidence of residual mitral valve incompetence in many patients. In the few who had severe incompetence at the mitral valve before repair, the results have been considerably less satisfactory than in the group as a whole; therefore, further work is needed on this aspect of the problem.

Of the 614 open-heart operations performed at the Mayo Clinic for acquired aortic valvular disease, 130 were performed on patients who also required repair of other valves. Review of the remaining 484 operations resulted in the following observations. Operation for acquired aortic valvular disease may now be accomplished with a hospital mortality rate of 4%. The incidence of late death and failure of patients to improve has averaged 44% for previously employed techniques of valvular repair. Failure of the valve or prosthesis to function properly was the most common cause of late failure after operations in which these earlier methods were used. In the 138 more recent cases, in which operations employing the aortic ball valve (Starr-Edwards prosthesis) were used, the incidence of late failure has been reduced to 14%, and failure of the prosthesis to function properly has not yet occurred in the absence of infection. Late bacterial endocarditis and thromboembolism were the most serious problems associated with use of the ball-valve prosthesis. In contrast with the late results of the former techniques, use of the ball valve has resulted in improvement for 79% of the patients; in the great majority of these there has been a dramatic return to normal living. Despite the highly satisfactory results of current methods, the fact that 14% of patients have already died after an initially successful operative result, and that another 12% have suffered complications causing their late result to be less than totally satisfactory, indicates that the policy of recommending for operation only those patients who have significant and progressive cardiac disability should be continued.

The effect of valvular insufficiency on left ventricular volumes was studied by an angiographic method in 37 patients. Ejection of the additional volume load imposed by valvular insufficiency was achieved by an increase in end-diastolic volume and not by increasing the proportion of end-diastolic volume ejected. Of the 37 patients, 16 (43 per cent) had a significant reduction in the fraction of end-diastolic volume ejected per beat. These patients performed significantly less stroke work from a given end-diastolic fiber length (end-diastolic volume) than did the others and evidence is presented that they had impaired myocardial function. An index of myocardial contractility is derived which relates stroke work to end-diastolic volume. The magnitude of left ventricular volumes is determined in part by the severity of the volume load but a further increase in volume without necessarily a further increase in ejection occurs in those patients with impaired myocardial function. Valvular insufficiency is quantitated from the difference between left ventricular ejection volume determined angiographically and forward stroke volume determined from indicator-dilution curves. The results show good agreement with subsequent surgical findings in the 15 patients who underwent operation.

Hemodynamic studies were made 2 weeks after repair of tetralogy of Fallot in 18 cases and 2 months to 6 years after operation in 5 cases. Intracardiac and intravascular pressures, oxygen uptake, arteriovenous oxygen content difference, cardiac output, heart rate, stroke index, and pulmonary and systemic resistance were measured. Residual intracardiac shunts and residual pulmonary stenosis and incompetence were assessed. Results were compared with similar studies on postoperative days 1, 2, and 3. Further insight into patterns of convalescence as well as into the favorable hemodynamic state usually pertaining after repair are provided by these data.

Cardiac output and related variables were measured in patients after open intracardiac surgery. Factors affecting cardiac performance during this period were the original anatomic lesions, the details of the operative procedure, ventricular-outflow resistance, transfusion of blood, the stage of convalescence, and digitalis. In postoperative patients, metabolic rate, level of hemoglobin, and level of oxygen in arterial blood varied more widely and acutely than in nonsurgical patients, resulting in a less predictable relation between cardiac output and oxygen saturation of mixed venous blood. Therapeutic applications of these observations were discussed.

Physiologic studies have been carried out during the first 3 days after intracardiac repair of tetralogy of Fallot. All patients survived. The ratio between systolic pressure in right ventricle and a systemic artery was 0.7 or less in all cases and did not vary significantly during the period of study. Residual left-to-right shunts of moderate degree were demonstrated in three patients (repaired with Teflon prostheses). In one of these three, no definite evidence of shunt could be found 2 weeks after operation. Additional abnormal circulatory pathways exist in these patients. Clear evidence was obtained of left-to-right shunting through aorticopulmonary collateral connections in one case. Systemic index was usually below normal or in the low normal range. It was usually lower on the second and third postoperative days than on the first postoperative day. Left atrial pressure was sometimes strikingly higher than right atrial pressure 30 minutes after repair, but not thereafter. Pulmonary vascular resistance was normal or slightly elevated. Gas exchange and management were adequate to maintain normal or near normal oxygen and carbon dioxide levels in arterial blood. Mild metabolic acidosis existed on the first 2 days, but had generally cleared by the third day. The implications of these data are discussed relative to ventricular function and performance, adequacy and technic of surgical repair, administration of blood after operation, and the state of preparedness in the lung and left ventricle in patients with tetralogy of Fallot.

Nineteen patients with ventricular septal defect and severe aortic valvular incompetence have been operated on at the Mayo Clinic. There were two early deaths and two late deaths. The ventricular septal defect was located high and anteriorly in the septum and was often small. Aortic valvular incompetence was due, in most cases, to a deformed, prolapsing right coronary cusp. Mild to moderate degrees of infundibular pulmonary stenosis coexisted in nine patients. Repair of the ventricular septal defect was readily accomplished in most cases by direct suture, and relief of obstruction to right ventricular outflow was effected, when required, by resection of the crista supraventricularis. Repair of the aortic incompetence was attempted by a variety of means, but the incidence of persistent significant regurgitation was high, except when prosthetic cusp replacement was used. It is currently our policy to defer operation in children unless there are significant symptoms. When the patient is past the age of about 12 to 14 years, operation is advised under proper circumstances, and it consists generally of suturing of the ventricular septal defect and replacement of the right coronary cusp of the aortic valve.

Sixteen patients were studied immediately and for 3 days following surgical closure of ventricular septal defect. In eight patients with absent or mild pulmonary vascular disease, convalescence was uneventful and only small deviations from normal in cardiac output, blood gas levels, and acid-base profile were observed. The remaining eight patients had pre-existing moderate or severe pulmonary vascular disease. Values for cardiac output were abnormally low at some time in the postoperative period in all but two of these eight patients. Failure to survive was clearly related to a low cardiac output in four of the five nonsurvivors. Reduction in cardiac output observed in this group of patients is believed to be based in major part on the pre-existing increased resistance to blood flow through the pulmonary vascular bed and also to impaired right ventricular function following operation. No evidence was obtained to suggest that major changes in pulmonary vascular resistance occurred in the immediate postoperative period in patients with moderate or severe pulmonary vascular disease following closure of ventricular septal defect. Right ventricular function following atriotomy or transverse ventriculotomy was less impaired than after vertical ventriculotomy.

Physiologic observations were made on eight patients following repair of atrial septal defect or total anomalous pulmonary venous connection. A pattern of changes in cardiac output and atrial pressures during the first 3 postoperative days was noted. Cardiac output was abnormally low in some patients with obstructive pulmonary vascular disease or low atrial pressures. Transfusion of whole blood was effective in elevating cardiac output in the operating room and after operation. Left atrial pressure was higher than right atrial pressure in the operating room. Postoperatively left and right atrial pressures tended to become equal in some patients, and the levels were slightly elevated. Heart rate did not seem to be directly related to cardiac output. Ventilation was adequate with regard to elimination of carbon dioxide. Arterial oxygen saturation was maintained at 93 per cent or more by the use of oxygen-enriched mixtures. The difference in arteriovenous oxygen content was inversely related to cardiac output. Acidemia was present 2 to 4 hours after operation, but in general the pH of arterial blood had returned to normal by day 2. Some mechanisms possibly related to the observations are discussed.