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Biomedical subjects

H M Spotnitz

Publications and source records attributed to H M Spotnitz.

At least 109 records · Page 6Linked to original sources
PubMed1979

Pharmacologic antagonism of beta-adrenergic blockade in dogs. I. Hemodynamic effects of isoproterenol, dopamine, and epinephrine in acute propranolol administration.

Hemodynamic effects of isoproterenol, dopamine, and epinephrine were studied before and after acute beta-adrenergic blockade in 16 open-chest, anesthetized mongrel dogs. Beta blockade was induced with 1 mg. per kilogram of intravenous propranolol. Cardiac output measurements were obtained by thermal dilution, and pressure recordings were obtained in the right ventricle, pulmonary artery, left atrium, left ventricle, and aorta. Derived parameters included stroke volume, pulmonary and systemic vascular resistances, and peak left ventricular dP/dt. In the presence of propranolol, epinephrine became a lethal drug in large doses and did not increase cardiac output in standard doses. Dopamine, in 25 to 50 mcg. per kilogram per minute doses, increased arterial pressure and systemic resistance; cardiac output was diminished compared with dopamine, 10 mcg. per kilogram per minute, prior to propranolol, as a result of increased resistance and decreased LV contractility. Isoproterenol, 0.6 to 0.9 mcg. per kilogram per minute, 15 to 20 times standard dosages, had moderately positive inotropic effects and increased cardiac output. Left ventricular systolic pressure with isoproterenol after propranolol was reduced when compared with effects of smaller doses prior to propranolol. These observations suggest that none of the catecholamines studied would be optimal for circulatory support in heart failure in the presence of propranolol. The present results define a pharmacologic basis for design of appropriate drug combinations for circulatory support in beta-blocked animals.

Adrenergic beta-Antagonists↗
PubMed1979

Left ventricular mechanics of counterpulsation and left heart bypass, individually and in combination.

Counterpulsation and left heart bypass devices have been successfully used to salvage patients with severe left ventricular power failure following cardiopulmonary bypass. Each of these techniques is believed to reduce or minimize myocardial work, yet the effects of these devices on the force of myocardial contraction have not been defined. In the present investigation the effects of counterpulsation produced by intravascular (intra-aortic balloon pumping) and extravascular (pulsatile assist device) balloon devices, partial left atrial-aortic bypass, and total bypass on left ventricular mechanics were examined. The devices were studied individually and in combination in 10 anesthetized open-chest dogs. Left ventricular wall stress, external work, and contractility indices were calculated by computer using a changing volume spherical model of the left ventricle. Results indicate that although all currently available circulatory assist devices reduced peak left ventricular wall stress, a spectrum of relative effectiveness progressed from intra-aortic balloon pumping or pulsatile assist device alone through the combination intra-aortic balloon pumping plus the pulsatile assist device. Partial left heart bypass was more effective than intra-aortic balloon pumping plus the pulsatile assist device in reducing peak wall stress, but the difference was small. Total left heart bypass was vastly superior to any of the other modalities tested in its effects on peak wall stress as well as external work. The addition of counterpulsation to partial or total left heart bypass produced minimal changes in left ventricular systolic mechanics.

Animals↗
PubMed1978

Clonidine withdrawal.

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Cardiac Surgical Procedures↗
PubMed1978

[Counterpulsation by means of a new device with a pulsatile blood flow in open heart operations (author's transl)].

A new counterpulsation method in operations on an open heart is described. Clinical experience in the use of the new device in 124 patients, which also makes it possible to produce a pulsatile flow of blood in the system of extracorporeal circulation, testifies to its effectiveness. The authors claim that the positive changes in cardiac output, diastolic and systolic pressure, and coronary circulation are among the factors which cause an improvement in the final result of the operation in patients with severe valvular diseases and ischemic heart disease.

Adult↗
PubMed1977

A pulsatile assist device (PAD) for use during cardiopulmonary bypass.

A pulsatile assist device (PAD) has been developed to convert roller pump flow to pulsatile flow in a simple fashion. The device can also be used as an arterial counterpulsator before and after cardiopulmonary bypass. The PAD has been used in 125 adult patients undergoing open-heart operations for coronary artery or valvular heart disease or the combination. Ninety-two patients were in New York Heart Association Functional Class III or IV or had ejection fractions of less than 0.3. The PAD functioned as a hemodynamically effective arterial counterpulsator before and after perfusion. All patients were successfully weaned from bypass with the PAD. There has been 1 intraoperative death and 2 late deaths. Only 1 patient had a perioperative myocardial infarction, and this person was successfully treated with intraaortic balloon pumping. We believe the PAD is a simple and reliable device for intraoperative counterpulsation and for the creation of pulsatile cardiopulmonary bypass. More important, use of the PAD may decrease both the incidence of perioperative myocardial infarction and the need for postoperative intraaortic balloon pumping.

Adult↗
PubMed1977

An improved method of myocardial protection with pulsation during cardiopulmonary bypass.

A new valveless pulsatile assist device (PAD) has been developed that converts roller pump flow into synchronized pulsatile flow. The PAD can also be used as an arterial counter-pulsator (ACtP) before and after cardiopulmonary bypass (CPB). The PAD was employed in 100 adult patients undergoing open heart surgery for coronary artery and/or valvular heart disease. Seventy-three of these patients were NYHA class III or IV, had ejection fractions of less than 0.3, or an LVEDP greater than or equal to 18 mm Hg. Sixty-one patients underwent coronary artery bypass alone, 17 valve replacement alone, three ventricular aneurysm alone, 12 combined coronaries and valves, and seven combined coronaries and ventricular aneurysms. The device functioned as a hemodynamically effective ACtP before and after CPB. During CPB, pulse pressures of 40-50 mm Hg were readily obtained. Urinary outputs during CPB were increased on the PAD when compared to a control group (9.18 +/- 0.68 cc/min vs 3.90 +/- 0.34 cc/min). In addition, during CPB, coronary graft blood flow (CBF) increased an average of 21.4 +/- 6.1% with the PAD, and after CPB, CBF increased an average of 25.0 +/- 5.9%. Free plasma hemoglobins after CPB were not elevated. Only one patient had a perioperative myocardial infarction, and this patient was successfully treated with intra-aortic balloon pumping. It is suggested from these data that use of the PAD may decrease both the incidence of perioperative myocardial infarction and the need for postoperative intra-aortic balloon pumping.

Assisted Circulation↗
PubMed1977

Increased cardiac output by downstream pumping with a reversed unidirectional intra-aortic balloon.

Downstream and upstream pumping with unidirectional intra-aortic balloons was compared in 8 open-chest normal mongrel dogs anesthetized with pentobarbital. Downstream pumping effect a 32 per cent increase in cardiac index, a 24 per cent decrease in systemic resistance, and a 2 per cent decrease in heart rate. Upstream pumping did not significantly affect these parameters. Mean aorta pressure proximal and distal to the balloon was not altered significantly by pumping in either direction. This unique observation of increased cardiac output may have important implications for the treatment of low output cardiac failure. Preliminary studies including baroreceptor denervation suggest that a reflex mechanism may be involved.

Animals↗