McGoon, Dwight C.

The ability of a left ventricular balloon pump to provide support of the circulation when myocardial function had been severely impaired was examined in six dogs. When the unassisted damaged left ventricle could not maintain systemic blood flows adequate for survival, left ventricular balloon pumping resulted in peripheral blood flows which ranged from 37 to 77 ml/min/kg. These balloon-generated blood flows have been maintained for periods up to three hours. Assist of the circulation by balloon pumping was accompanied by an increase in systemic arterial blood pressure and a decrease in left atrial end-diastolic pressure. The effectiveness of left ventricular balloon pumping was reduced in hypovolemia and in the presence of ventricular extrasystolic beats. Left ventricular balloon pumping was not effective in generating a sustained peripheral flow of blood when the heart was fibrillating.

The results of complete repair of double-outlet right ventricle without pulmonic stenosis in 18 Mayo Clinic patients are analyzed; the over-all operative mortality rate was 22%. Pulmonary vascular obstructive disease and a second ventricular septal defect of the atrioventricular canal type were associated with a higher mortality rate. The difficulties in the diagnosis of this uncommon condition are emphasized. Patients with double-outlet right ventricle without pulmonic stenosis should have complete repair early in life before the onset of severe pulmonary vascular obstructive disease-the only specific contraindication to operation. Pulmonary artery banding may be preferable as a first-stage palliative procedure in infants less than six months old who do not respond to medical therapy.

Four cases of ventricular septal defect and ventricular aneurysm after myocardial infarction are reported. The clinical findings and surgical results in these four cases and in eight previously reported patients with this combination of complications are summarized. Resection of the ventricular aneurysm and closure of the ventricular septal defect appear indicated, both on theoretical grounds and in view of the excellent results observed in six patients who underwent combined repair. In one of our patients, closure of the ventricular septal defect and resection of the ventricular aneurysm were possible with only a single suture line, as these defects were anatomically contiguous.

Postoperative embolism occurred in 35 of 546 patients traced for 2 to 15 years after surgical repair of uncomplicated ASD. A total of 58 embolic episodes occurred, resulting in the death of 11 of these 35 patients. The incidence of embolism was not significantly related to the technique used for surgical repair. Six of the nine patients who had had a preoperative embolism also had an embolism in the postoperative period. The most significant factors associated with an increased risk of postoperative embolism were increased age of the patient, atrial fibrillation, and pulmonary hypertension, all of which are interrelated: seventy-seven per cent (27/35) of patients having a postoperative embolism had either atrial fibrillation or pulmonary hypertension, and 77% (27/35) of patients with postoperative embolism were more than 40 years old at the time of the first embolism. Because actuarial analysis suggests that 30% of patients more than 40 years of age who have atrial fibrillation after repair of ASD may have an embolism within 10 years postoperatively, continuation of anticoagulation therapy indefinitely in these patients is suggested. The highest risk of embolism occurs in the early postoperative period, suggesting the advisability of anticoagulation therapy for all adult patients during convalescence.

A patient with an atrial septal defect, paroxysmal tachycardia, and the Wolff-Parkinson-White syndrome (type B) had epicardial exploration to determine the nature of the excitation anomaly. Right bundle-branch block in association with the WPW syndrome (type B) was evidenced by the late activation (0.12 sec) of the epicardium over the outflow tract of the right ventricle. Early activation of the base of the right ventricle (near the atrioventricular groove at the right border of the heart) was interpreted as indicating an actively conducting atrioventricular muscle bridge (bundle of Kent) in this region. During paroxysms of tachycardia, the ventricular area excited much later than when sinus mechanism was present, and the adjacent right atrium was excited in sequence. This sequence supported the concept of a circus movement, that is, movement from atrium to ventricle via atrioventricular bundle (His) and ventricle to atrium via a muscle bridge (Kent). Injection of procaine into the base of the right ventricle abolished the pre-excitation of the ventricle.

Two cases in which large intramural ventricular cardiac fibromas were successfully removed from children are reported. In one the fibroma was principally septal, and in the other it lay in the free wall of the left ventricle. These are the second and third such operations reported. A review of these two cases plus 34 other reported cases of cardiac fibroma indicates that a primary mural tumor of the heart should be suspected in patients, particularly children, with unexplained cardiac failure, unexplained cardiac dysrhythmia, intracardiac calcifications, irregular shadows on roentgenograms, or unexplained newly developing cardiac symptoms and murmurs. Angiocardiography is the best way of confirming the diagnosis. In view of the potential hazard of these tumors, their surgical removal should be undertaken, and this experience indicates that even very large and extensive intramural ventricular tumors may be removed successfully.

The incidence of thromboembolism after insertion of prosthetic cardiac valves is related to the type of prosthesis and in the cases reviewed here was highest for the ball-valve prosthesis. The risk of thromboembolism was studied by constructing actuarial curves showing the proportion of patients with embolism at increasing time intervals postoperatively. Such curves for the patients studied suggest that the risk of thromboembolism diminishes with time, particularly by the third postoperative year. The risk was remarkably similar for patients having aortic, mitral, and multiplevalve replacements, being 15% for the first 6 postoperative months, another 8% for the next 6 months, and another 20% for the next 2 years. Emboli lodged in cerebral, coronary, renal, and other sites in these patients in diminishing frequency. The risk of fatality averaged 15%. None of the nonfatal embolisms resulted in significant continuing disability, save for 7% of the cerebral embolisms. A beneficial effect of anticoagulation was demonstrated for patients having replacement of the aortic valve with a ball-valve prosthesis, particularly when this treatment was carefully controlled. In the latter group, the risk of thromboembolism was less than 5% 2 years postoperatively.

Between 1945 and 1961 50 patients with aortic dissection were seen at the Mayo Clinic. Survival information for prognostic purposes was available in 40 patients and revealed that more than half of the patients were dead within a week. Of 15 patients who survived the acute phase (2 weeks) more than half were dead within a year. The cause of death was determined by necropsy in 24 patients and 22 died of external rupture of the dissecting aneurysm. In 11 patients a site of re-entry in the dissection was found and in all of these patients external aortic rupture had occurred also. The surgical approach to the treatment of aortic dissection is discussed in the light of these findings. The relationship of the location of the primary tear, blood pressure, and the age of the patient to prognosis is reviewed.

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.