Jack M. Matloff

Alteration of mechanical performance of the ventricle by intraaortic balloon counterpulsation

Abstract Intraaortic balloon counterpulsation has been shown to reduce the immediate mortality due to acute myocardial infarction in dogs. Previous studies have emphasized the importance of the absolute or relative increases in coronary blood flow that result from augmentation of diastolic aortic pressure. This study was designed to clarify the role of the decreased systolic pressure characteristic of counterpulsation in increasing the cardiac output. Eleven dogs were studied without intervention except for counterpulsation. A decrease in peak left ventricular pressure from 138 ± 7 to 116 ± 6 mm Hg ( P Hg . As a result of the decreased impedance to ejection, peak aortic flow, stroke volume and cardiac output increased by 15 percent. In 6 dogs studied after acute myocardial infarction secondary to ligation of the left anterior descending coronary artery, there were parallel but less marked changes in the hemodynamic measurements. The external performance of the ventricle when evaluated in terms of peak flow, stroke volume and output was an inverse function of the impedance to ejection. Since effective assistance to the failing heart must result in increased external performance, the importance of adequate reduction of systolic impedance must not be underestimated.

Dynamic characterization of premature ventricular beats and ventricular tachycardias

Abstract The contraction patterns induced by ectopic ventricular premature beats and ventricular tachycardias occurring in man during left ventriculography were analyzed. These were compared with contraction patterns induced by ventricular premature beats and tachycardias produced in five dogs by epicardial left ventricular apical or basilar stimulation. Two patterns of contraction observed in the animals corresponded to two patterns observed in man. Apically stimulated left ventricular beats produced an “hourglass” type of contraction pattern and were hemodynamically more effective than beats arising from basilar stimulation, which produced an inverse “teardrop” pattern. The same patterns were reproduced by experimental ventricular tachycardias. These observations stress the importance of a normal sequence of ventricular contraction to optimal cardiac function in man and warn against the hazards of misinterpretation of the left ventricular contraction pattern if the beat originates ectopically during ventriculography.

Hemodynamic Effects of Glucagon in Patients Following Prosthetic Valve Replacement

The intravenous administration of 5.0 mg of glucagon to 16 digitalized patients on the first postoperative day after prosthetic valve replacement resulted in significant cardiac inotropic effects. Since glucagon is effective in the presence of catecholamine depletion or beta-adrenergic blockade and appears to have little arrhythmogenic potential, it would appear to be a useful agent for the treatment of myocardial depression occurring in association with open cardiac surgery.

Hemodynamic effects of glucagon and intraaortic balloon counterpulsation in canine myocardial infarction

Abstract The hemodynamic effects of glucagon (50 μg/kg) and intraaortic balloon counterpulsation were investigated in open chest anesthetized dogs after production of myocardial infarction and cardiogenic shock. Glucagon produced striking increases in arterial pressure, cardiac output and maximal left ventricular dp/dt together with a reduction in left ventricular end-diastolic pressure and systemic vascular resistance. The condition of most animals was stabilized at a viable level with 1 or more doses of glucagon. The effects of counterpulsation during severe cardiogenic shock were slight, although good counterpulsation was always achieved during control studies with normal pressure. When counterpulsation was instituted in combination with glucagon therapy there was an increase in mean arterial pressure together with a reduction in maximal left ventricular dp/dt and peak systolic pressure. Thus, counterpulsation tended to reduce the increased oxygen cost of the inotropic effects of glucagon. We suggest that an appropriate combination of counterpulsation and inotropic support (as with glucagon) may be better than either method alone.

Control of Postcardiac Surgical Tachycardias with Propranolol

Twenty-two patients manifesting arrhythmias refractory to conventional therapy have been treated with propranolol 1 to 19 days after cardiac surgery. Rapid control of ventricular response to supraventricular arrhythmias, abolition of ventricular irritability caused by digitalis excess, and frequent conversion of acute atrial fibrillation or flutter were attained. Control of the arrhythmia was achieved in all but one instance. No significant side effects were encountered, although the potential risks of propranolol are stressed. Propranolol appears to fill specific needs unsatisfied by standard therapy for arrhythmias developing after cardiac surgery.

Hemodynamic Response to Discoid Mitral Valve Replacement

Hemodynamic studies were performed before and daily for 7 to 10 days after mitral valve replacement with a discoid prosthesis in 15 patients. Left atrial mean pressure fell from a mean of 27.5 mm Hg before surgery to normal levels (mean 11 mm Hg) within 24 hours of surgery. Cardiac index reached normal levels (mean 2.97 L/min/m2) within 48 hours of valve replacement, and remained in the normal range throughout the early postoperative period in 12 of the 15 patients. The association of normal left atrial pressure and cardiac output in response to the increased metabolic demands of the postoperative period has not been reported with caged-ball mitral valve replacement. Pulmonary artery mean pressure and pulmonary vascular resistance showed a sharp decrease toward normal in the early postoperative period. In seven patients with systemic pulmonary hypertension, pulmonary artery mean pressure decreased from 72 mm Hg before surgery to 38 mm Hg at 7 to 10 days. The observed hemodynamic findings in these patients are consistent with experimental evidence that discoid mitral prostheses offer less resistance to blood flow than caged-ball mitral prostheses.

Pulmonary Arteriovenous Admixture in Cardiac Surgical Patients

Patients undergoing cardiac surgery with cardiopulmonary bypass for mitral insufficiency develop significant hypoxemia after surgery. This is due mostly to true shunt, but there is a significant contribution due to ventilation-perfusion abnormalities. The condition persists for eight to ten days but is reversible. Breathing 100% oxygen in the postoperative period reduced cardiac output and pulmonary artery pressure and increased arteriovenous oxygen content differences. A redistribution of pulmonary blood flow is suggested by these findings, and accordingly the value for true shunt may vary with changing inspired oxygen concentrations.

Use of a Polyol in the Prevention of Hemolysis due to an Antifoam Agent in Pump Oxygenators

Studies of the hematological effects of a polymethylsiloxane defoaming agent used in pump oxygenators have shown it to have significant hemolytic properties. This action is principally a direct one upon the red cell and requires some degree of associated mechanical stress. Pluronic, a nonionic emulsion stabilizer prevents the hemolytic process without interfering with the defoaming process.