Tricuspid and pulmonary valve obstruction relieved by removal of a myxoma of the right ventricle

The first case of spontaneous and permanent complete heart block in a patient with well documented muscular subaortic stenosis is reported. Hemodynamic observations were made during the periods of complete heart block and paced rhythm. The exact cause of the complete heart block in this patient is uncertain.     

Atrial septal defect (secundum) associated with mitral regurgitation

Mitral regurgitation was found in 6 percent (46 patients) of all patients with a secundum atrial septal defect who were operated on during a 13 year period at the Mayo Clinic. The presence of two separate systolic murmurs, expiratory splitting of the second heart sound and evidence of overactivity of both the right and the left ventricles were the most reliable clues to the diagnosis. Nineteen of 39 patients (49 percent) had increased pulmonary arterial pressure, but only 3 patients had obstructive pulmonary vascular disease. Electrocardlographic findings rarely helped differentiate the patient who had a secundum atrial septal defect and associated mitral regurgitation from the one who had an isolated septal defect. The causes for the mitral regurgitation varied. Six patients had rheumatic valvulitis, 8 had redundant mitral valve tissue with prolapsing leaflets, 9 patients had two or more causes, and in 18, no cause for the regurgitation could be found.     

The palliative Mustard operation: rationale and results.

The tendency toward development of severe pulmonary vascular obstructive disease in patients with complete transposition of the great arteries and associated large ventricular septal defect has been well documented. The physiologic consequence of this process is a significant reduction in intercirculatory mixing, resulting in increasingly severe levels of systemic arterial hypoxemia, compensatory polycythemia and an associated significant increase in symptoms. Data indicate that definitive surgical correction in patients with pulmonary arteriolar resistance of more than 10.0 units m2 is associated with a prohibitive operative mortality. However, the "palliative" Mustard operation (that is, intraatrial baffle repair, leaving the ventricular septal defect open) can be accomplished with relatively low risk and substantial hemodynamic benefits to the patient. It is erroneous to assume that the result of the operation will be a mere "reversal" of the preoperative systemic arterial and pulmonary arterial saturations, as shown by a review of the hemodynamic changes attributable to the operation. After the operation, systemic arterial saturations of 80 to 93 percent have been achieved, with a concomitant significant reduction in hemoglobin concentration, to a near normal level in some. Although the long-term prognosis in such patients is unknown, the reduction in symptoms and increase in exercise tolerance soon after operation are most gratifying.     

Tissue valves

The search for an ideal replacement for diseased intracardiac valves has resulted in the use of many tissue valves, including homografts, heterografts and valves of autologous and heterologous fascia lata and of pericardium. Operative mortality in experienced hands has been comparable to that of other operations using prosthetic valves. Sterilization and preservation techniques probably render the graft nonviable in all instances. Although early function has been satisfactory, late deterioration of leaflet tissue has led to valve failure in a high percentage of cases. At present, glutaraldehyde-prepared heterografts and fresh antibiotic-sterilized homografts appear to have the longest durability of the various tissue grafts used for valve replacement. The primary advantage of tissue valves has been the essential elimination of thromboembolic complications, and the primary problems have been infectious endocarditis and late graft deterioration.     

Factors influencing systemic arterial oxygen saturation in complete transposition of the great arteries

Hemodynamic data from 100 patients with complete transposition of the great arteries, all 1 year old or older, were reviewed. Only 2 patients, at rest and breathing room air, had a systemic arterial oxygen saturation level as high as 85 percent. In any patient with dextrotransposition of the great arteries and a systemic arterial saturation of 85 percent or greater, there is a strong likelihood of a single ventricle.

At a given level of oxygen consumption, 3 potential variables influence systemic arterial oxygen saturation in transposition: (1) magnitude of the intercirculatory mixing, (2) hemoglobin concentration and (3) magnitude of the recirculated systemic mixed venous flow. The first 2 factors are directly related to systemic saturation, and the third is inversely related.

Decreasing total pulmonary blood flow, secondary to increasing pulmonary vascular disease or pulmonary stenosis, results in decreased intercirculatory mixing and a decrease in systemic arterial oxygen saturation. This decrease in saturation is partially compensated for by an increase in hemoglobin concentration. An index calculated from the level of systemic arterial oxygen saturation divided by the value for hemoglobin concentration is useful in follow-up studies to determine the presence of pulmonary vascular disease or pulmonary stenosis. This index will often eliminate the need for repeated cardiac catheterizations before definitive corrective surgery is carried out.     

Right and left ventricular function after the Mustard procedure in transposition of the great arteries.

Right and left ventricular function was assessed at cardiac catheterization in 33 asymptomatic patients 0.5 to 11 years (mean 4.6) after the Mustard operation for complete transposition of the great arteries. Ages at operation had ranged from 0.5 to 16 years (mean 4.2 years). Right ventricular function was assessed using videodensitometric determination of ejection fraction and ventricular volume data. Ventricular volumes were obtained by computerized video analysis utilizing Simpson's rule. The right ventricular ejection fraction was 37 +/- 11 percent (standard deviation), as assessed with videodensitometry and 42 +/- 10 percent as assessed with ventricular volume--both values less than normal (P less than 0.001). Right ventricular end-diastolic volume was significantly greater than normal (P less than 0.001) and averaged 202 +/- 70 percent, but left ventricular end-diastolic volume averaged only 125 +/- 53 percent. These observations after the Mustard operation indicate that right ventricular function is seriously decreased with relatively preserved left ventricular function. They support efforts for surgical correction utilizing the left ventricle as the systemic ventricle.     

Regional left ventricular wall dynamics before and after sublingual administration of nitroglycerin

Regional wall dynamics of the left ventricle before and after sublingual administration of 0.6 mg of nitroglycerin were determined from left ventricular angiograms in 27 patients undergoing coronary arteriography. Regional wall dynamics were quantitatively measured from 60/sec determinations of wall thickness and derived peak rate of systolic wall thickening (peak dTw/dt) in selected sites of the left ventricle. A total of 70 regions were studied. Analysis of the same segment before and after administration of nitroglycerin revealed that the mean change in peak dTw/dt was +1.97 cm/sec in segments with an initial peak dTw/dt of less than 5 cm/sec, in contrast to a change of +0.66 cm/sec in segments with an initial control value of 5 cm/sec or greater. Akinetic or dyskinetic areas did not show improvement after nitroglycerin. In 11 left ventriculograms, an area that was initially hypokinetic manifested an increase in rate of wall thickening after nitroglycerin. The mean increase in peak dTw/dt in anterior segments with electrocardiographic evidence of myocardial infarction was 0.18 cm/sec (P <0.05) after nitroglycerin, compared with a mean change of 1.33 cm/sec in anterior segments without such evidence. This study presents evidence for a regional myocardial response to nitroglycerin with differing responses within the same ventricle apparently depending upon the functional state of the underlying myocardium.     

Idiopathic hypertrophic subaortic stenosis: Long-term surgical follow-up

The results of surgery in 43 patients with idiopathic hypertrophic subaortic stenosis are reported. Twenty-eight patients were male and 15 female; their mean age was 34 years. Dyspnea, angina pectoris and dizziness or syncope were the most common symptoms, in decreasing frequency. Before the operation, 3 patients were in New York Heart Association functional class I, 9 in class II and 31 in classes III and IV. The mean resting peak ventricle-arterial systolic pressure gradient was 77 mm Hg (39 patients), and mean left ventricular end-diastolic pressure was 22 mm Hg (34 patients). The operative mortality rate was 16 percent (7 of 43 patients) for the entire group, but only 8 percent for patients who underwent isolated left ventricular outflow tract myectomy (3 of 36 patients). There were four late sudden deaths. One patient has been lost to follow-up. The remaining 31 patients have been followed up for a mean of 84 months (range 12 to 160 months); 14 patients are in functional class I, 14 in class II and 3 in classes III and IV. Of the symptomatic patients, six are taking propranolol and eight are taking digitalis or diuretic agents, or both. Complications included complete heart block in 5 patients, complete left bundle branch block in 15 and left ventricular aneurysm in 3. Our study, which is one of the largest with the longest postoperative follow-up period, documents that surgery results in good to excellent alleviation of symptoms in survivors. We currently recommend surgery for the symptomatic patient who has not responded to therapy with propranolol.     

Reduction of intimal thickening in canine coronary bypass vein grafts with dipyridamole and aspirin

The potential benefit of platelet inhibitor drugs on coronary arterial bypass vein grafts was assessed in dogs with magnification-corrected angiographic luminal measurements and quantitative histologic evaluation of the vein grafts. There were 11 control animals and 11 animals treated with dipyridamole, 55 mg/day, plus aspirin, 325 mg/day. Eighteen animals with patent grafts were studied when electively killed 2, 4 or 6 months after grafting. At 14 days, there was greater angiographic narrowing in the most distal 1 cm of vein grafts in control than in treated dogs (P < 0.01). This same angiographic narrowing persisted in control dogs until they were killed (P < 0.03). Computer-assisted measurements of the entire area of intimal thickening were done on vein graft cross sections taken 1 cm from the distal anastomosis. The circumference of the vein grafts at the intimal-media junction was measured from the same section and the potential maximal luminal area calculated. The calculated luminal narrowing due to intimal thickening was greater in control than in treated dogs (P < 0.03). These data correlate well with the demonstrated angiographic narrowing. The findings indicate that the degree of early intimal thickening that persists 2 to 6 months postoperatively in canine coronary bypass vein grafts may be reduced by the platelet inhibitor combination of dipyridamole plus aspirin.     

Reduction of thrombosis in canine coronary bypass vein grafts with dipyridamole and aspirin

The potential benefit of platelet inhibitor drugs in reducing early thrombosis of coronary arterial vein bypass grafts was assessed in dogs. There were 26 control dogs and 24 dogs treated with dipyridamole, 55 mg/day plus aspirin, 325 mg/day. The dogs in both groups were killed at 2 hours and 1, 2, 3, 7 and 14 days after operation. The grafts were perfused with flxative in vivo, harvested and examined with light microscopy. Severe alterations of the graft wall were observed in the dogs in both groups. The grafts in the control group had a high incidence rate of thrombosis, which occurred early after the operation; those in the treated group had a significantly reduced incidence of thrombosis (p = 0.025). Our study indicates that a combined regimen of dipyridamole and aspirin is effective in reducing early graft thrombosis in dogs.     

Two dimensional echocardiographic detection and measurement of the right pulmonary artery in pulmonary atresia-ventricular septal defect: Angiographic and surgical correlation

This study assessed the value of two dimensional echocardiography in patients with pulmonary atresia-ventricular septal defect in order to detect the presence of true pulmonary arteries, measure the dimension of the visible proximal right pulmonary artery and correlate these echocardiographic observations with angiographic and surgical findings. The data from 65 patients (age range 16 months to 54 years) with pulmonary atresia-ventricular septal defect who had both two dimensional echocardiographic and angiographic evaluation to determine the presence of pulmonary arteries were reviewed. Echocardiography allowed visualization of a right pulmonary artery in 55 (85 percent) of the 65 patients. Echocardiography detected a measurable proximal right pulmonary artery in 52 (98 percent) of 53 patients who had confluent pulmonary arteries confirmed with angiography. In three patients without confluence, a large systemic to pulmonary collateral artery was misinterpreted as the right pulmonary artery on two dimensional echocardiography. Right pulmonary arterial measurements on echocardiography (range 3 to 21 mm) showed excellent correlation with angiographic (r = 0.95) and surgical (r = 0.84) measurements.These data indicate that two dimensional echocardiography can be used to visualize proximal true pulmonary arteries (specifically, a right pulmonary artery) in a large proportion of patients with pulmonary atresia-ventricular septal defect; this finding usually denotes the presence of confluent pulmonary arteries. The data also suggest that this method can be reliably used for serial follow-up studies with noninvasive measurement of proximal right pulmonary arterial growth.     

Idiopathic hypertrophic subaortic stenosis in the young

Thirty-six young patients with idiopathic hypertrophic subaortic stenosis were studied. Twenty-seven patients were male and 9 female, and their mean age was 11.3 years (range 5 months to 20 years). Twenty-three patients (64 percent) had symptoms, the most common being dyspnea, angina and syncope. Diagnostic difficulties were encountered frequently in younger patients, especially those with right heart involvement, and in asymptomatic patients with murmurs suggestive of other cardiac defects. Patients were classified retrospectively into three groups on the basis of management. The first group consisted of 16 patients who were operated on; 4 of these patients died, 1 operatively and 3 suddenly late postoperatively (at 1.6, 2 and 10 years). The 12 long-term survivors (average follow-up period 6.2 years) have had good relief of symptoms. The second group comprised seven patients treated with propranolol; none of these died. The 13 patients in the third group received no therapy; 7 of these patients died, 6 suddenly and 1 from congestive cardiac failure. Idiopathic hypertrophic subaortic stenosis is a serious disorder that may present at any age and that may be difficult to diagnose. All patients with this disorder should be treated with propranolol; surgical intervention, although it does not totally abolish the risk of sudden death, appears to offer symptomatic improvement in most cases over a long-term follow-up period.