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Biomedical subjects

I Nagai

Publications and source records attributed to I Nagai.

At least 73 records · Page 4Linked to original sources
PubMed1976

Successful closure of ventricular septal defect through a left-sided ventriculotomy in corrected transposition of the great vessels.

Corrected transposition of the great vessels is often associated with other cardiac anomalies. Ventricular septal defect (VSD) is the most common among them. Closure of a VSD is usually performed through a right-sided ventriculotomy. We had previously closed the VSD through the right-sided ventricle in 2 patients with corrected transposition of the great vessels and in 2 others with double-outlet right ventricle with ventricular inversion, which resulted in complete heart block. Recently we have closed the VSD through the left-sided ventricle in 3 patients with corrected transposition, and no block resulted.

Adolescent↗
PubMed1975

A bidirectional respiratory flowmeter using the hot-wire principle.

We have devised a bidirectional respiratory flowmeter using the hot-wire principle. The flow-direction sensor consists of a pair of tungsten wires strung parallel to the platinum hot-wire one on each side of the platinum wire. When the gas stream passes through the transducer, the upstream wire is cooled and the downstream wire is heated by the gas stream producing a temperature difference between the two tungsten wires. The difference in resistance thus produced between them is detected and amplified by a differential amplifier whose output serves as a triggering signal of flow inversion. The switching times of the flow inversion of the present instrument are 3 ms during panting and 10 ms during quiet breathing, when the distances from the platinum wire to the tungsten wires are 1.6 mm. Artifacts produced by the delay in switching are practically negligible. The flowmeter can be adapted for many kinds of respiratory flow measurement, except under the condition when inflammable gases are used.

Humans↗
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↗