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Biomedical subjects

S Nitta

Publications and source records attributed to S Nitta.

At least 253 records · Page 14Linked to original sources
PubMed1976

Production of controlled reversible left ventricular failure in calves using intracoronary lidocaine hydrochloride: a useful method of evaluating left ventricular assist devices.

The experimental production of stable, controlled, short-term left ventricular failure is valuable in the evaluation of implantable circulatory support systems. Acute or chronic left ventricular failure produced by occlusion or embolization of coronary arteries results in muscle dysfunction and degrees of failure that may be difficult to control. The effects of varying amounts of intracoronary lidocaine were studied during short- and long-term evaluations of intracorporeal left ventricular assist pumping. In 8 Hereford calves the left main coronary artery was cannulated with an intracoronary catheter in open and closed chest preparations. Dose-related negative inotropic effects were noted when lidocaine was injected at individual doses of 50, 75, and 100 mg. Following 100 mg doses, mean aortic pressure, cardiac output, and maximum rate of rise of left ventricular pressure decreased; left ventricular end-diastolic pressure increased fourfold. Similar effects were noted with short continuous infusions of lidocaine. The initial responses to injection or continuous infusions, if effective, were noted within 40 to 60 seconds. Several episodes of failure could be produced with either method following recovery periods of 10 to 15 minutes. In all instances, actuation of a left ventricular assist device immediately reversed the hemodynamic effects of the pharmacologically induced failure.

Animals↗
PubMed1975

Evaluation of cardiac function and venous return curves in awake, unanesthetized cialves with an implanted total artificial heart.

1) The implanted TAH offers a method of evaluating the effects of varying physiologic demands cardiac output and venous return. 2) Cardiac output and venous return measurements offer a method of evaluating system design of the device and driving and control-logic improvements in awake, unanesthetized animals. 3) The obtained cardiac function and venous return curves suggest that the present TAH is less responsive to increases in right atrial pressure than the natural heart, but is still completely controlled by venous return. Therefore, it is extremely important to make every effort to eliminate any factor causing excessive venous return.

Animals↗
PubMed1975

Peripheral effects of cardiovascular drugs during total artificial heart pumping in the awake unanesthetized calf.

Effects of various drugs, such as Isuprel, Neo-synephrine, aminophylline and quinidine, have been evaluated and compared in both control and TAH calves. In the control calves, the cardiac effects of these drugs were overlapped by vascular effects. But in the TAH calves, pure vascular effects have been clearly shown. 1) The peripheral effects of Dibenzyline and Inderal were evaluated in the TAH calves. 2) From these results, it has been concluded that the TAH animal is a useful model for the study of the peripheral vascular response to drugs in awake, unanesthetized subjects.

Aminophylline↗