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Biomedical subjects

T Onitsuka

Publications and source records attributed to T Onitsuka.

162 records · Page 9Linked to original sources
PubMed1985

[The effects of intra-abdominal pressure on regional renal blood flow during peritoneal dialysis].

This experimental studies were designed to investigate the effects of intra-abdominal pressure (IAP) on renal regional blood flow and renal function during peritoneal dialysis (PD) for acute renal failure (ARF). The mongrel dogs were divided into four groups. Group I (n = 10): IAP of atmospheric pressure without PD (control group); Group II (n = 10): Intermittent PD with IAP of 10 mmHg; Group III (n = 10): Intermittent PD with IAP of 20 mmHg; Group IV (n = 10): Continuous PD with IAP of 3-5 mmHg. The following results were obtained. Significant decrease (p less than 0.01-0.05) of renal cortical blood flow (RCBF), total renal blood flow (TRBF), ratio of RCBF to renal medullar blood flow, renal perfusion pressure (RPP), cardiac index and urinary output, and increased renal vascular resistance and inferior vena caval pressure were observed in group III, but in group IV, values of these parameters returned to control level. The limit of influence to renal function was confirmed to be as follows. (1) IAP of 30 mmHg or more, (2) RPP of less than 65 mmHg, (3) TRBF of less than 2.2 ml/g/min, (4) and RCBF of less than 78 ml/100 g/min. These studies suggest that RPP are simple and excellent index to reflex renal hemodynamics, and the continuous PD are better procedure than the intermittent PD from a view of renal regional blood flow.

Abdomen↗
PubMed1982

Evaluation of limited resection of the lung for treatment of lung cancer.

The validity and indications of limited resection for lung cancer were studied based on the results of 34 patients with lung cancer who underwent surgery. This method appeared to be an effective technique for the preservation of the cardiopulmonary function after surgery, particularly in elderly patients. The prognosis of those who underwent limited resection for selected cases was not significantly different from that of those treated by lobectomy. Recurrences were seen exclusively in Stage II patients, most of whom had a poorly differentiated type of cell pathology and developed blood vessel involvement. It was concluded from this study that this technique can be feasibly applied to patients with a tumor of less than 3 cm located at the periphery of the lung and with the histologic picture of highly differentiated type.

Aged↗
PubMed1982

Pacemaker implantation in a neonate with congenital complete heart block--a case report.

Reported herein is our experience with pacemaker implantation in a neonate with complete AV block and without other concomitant cardiac anomalies. A male fetus exhibited an intrauterine heart block rate of about 40 beats per minute on the electrocardiogram. An emergency pacemaker implantation was attempted at birth by means of intravenous temporary pacing to relieve signs of congestive heart failure. On the 28th day of life, a myocardial electrode was fixed on the right ventricular wall and the generator was positioned on the left side of the subcutaneous abdominal wall. A technical device was designed by means of packing pacemaker wire in a loop-forming fashion with a silastic sheet and was made in such a way as to adjust with growth of the patient. During the 2 year follow-up period, this technique proved to be effective. Our experience also supports the contention that pacemaker implantation in the newborn is feasible and beneficial in the treatment of congenital complete AV block.

Cardiac Pacing, Artificial↗
PubMed1982

The limit of application of intraaortic balloon pumping (IABP) on canine myocardial infarction.

The limit of application of intraaortic balloon pumping was evaluated in cases of canine myocardial infarction produced by either ligation of the descending coronary artery and of branches in the right coronary artery or establishment of stenosis in the left main coronary artery. The limit of application of intraaortic balloon pumping was confirmed to be as follows: 1) stenosis of seventy-five per cent or more in left main coronary artery, 2) over 45 per cent infarction of the entire left ventricular free wall, 3) endocardial viability ratio of less than 0.65, 4) blood flow of less than 18 ml/min/100 g in the left circumflex coronary artery when the left descending coronary artery was ligated, 5) and less than 0.69 in the ratio of inside blood flow to outside of the left ventricular free wall, as related to regional myocardial blood flow.

Animals↗
PubMed1981

An experience using spiral vein graft as arterial substitute.

In two patients wih aneurysmal changes due to arteriosclerosis in the axillary and the subclavian artery respectively, spiral vein grafts were used in a substitute for vascular reconstruction. After resection of the aneurysm, these vein grafts resulted in an excellent adaptation to the recipient vessel. Complicated techniques were not required and the construction time was minimal. Such an approach may be used even in adjacent sites to a joint.

Aneurysm↗
PubMedDate not supplied

Detection of total assist and sucking points based on the pulsatility of a continuous flow artificial heart: in vivo evaluation.

Our novel control strategy for a continuous flow artificial heart by detecting the total assist and sucking points based on pump pulsatility was evaluated in acute animal experiments using beagle dogs and our mixed flow pump. The pump was installed as a left ventricular (LV) bypass through a left thoracotomy. To change LV contractility, the left coronary arteries were occluded for 30 min, followed by a 120 min reperfusion. To change LV end diastolic pressure (LVEDP), dextran solution was rapidly infused. To estimate the pump pulsatility without any specific sensor, we calculated the index of current amplitude (ICA), which was obtained from the amplitude of the motor current waveform divided by the simultaneous mean value. To investigate the basic characteristics of the ICA, the pump speed was changed temporarily from 2,300 rpm to 5,000 rpm. In 92% of all measurements, the ICA plotted against the pump speed had a peak point (t-point) that corresponded highly with the turning point from partial to total assistance. The ICA also had a trough (s-point) that corresponded with the beginning of severe sucking in most cases. Only preload significantly influenced pump flow rate at the t-point from among preload (LVEDP), afterload (SAoP), and contractility (max LV dP/dt), by which we can simulate Starling's law of the natural heart. We concluded that a continuous flow artificial heart could be well controlled by detecting the t-point and s-point.

Animals↗
PubMedDate not supplied

Detection of total assist and sucking points based on pulsatility of a continuous flow artificial heart: in vitro evaluation.

We investigated the basic characteristics of the pulsatility of motor current with an in vitro mock circuit that consists of a sac-type pulsatile pump (simulating the natural left ventricle), three reservoirs, and our mixed flow pump (MFP). There are three alternatives at the inlet of the MFP: 1) the left atrium (LA), 2) the left ventricle (LV), and 3) both (LALV). The motor current waveform was monitored. The pump speed of the MFP was changed from 0 to 7,000 rpm. We calculated the index of motor current amplitude (ICA), which was obtained from the amplitude of the motor current waveform divided by the simultaneous mean value. The ICA plotted against the pump speed had a peak point (t-point) that highly corresponded with the turning point from partial to total left heart assistance. The ICA also had a second specific point (s-point) that corresponded with the beginning of severe sucking. In LV and LALV aortic bypass, t- and s-points could clearly be detected. In LA aortic bypass, however, early and severe sucking occurred, and t- and s-points were not manifest. These data suggest that the assist status of continuous flow artificial heart can be estimated by detecting the t- and s-points.

Blood Flow Velocity↗
PubMedDate not supplied

The feasibility and efficacy of right ventricular assistance without thoracotomy.

Mechanical right ventricular assistance has never been percutaneously instituted. We invented a new method for administering right ventricular assistance without thoracotomy (RAWT) and evaluated its effects in acute experiments using dogs. To institute RAWT, an outflow cannula was inserted into the pulmonary artery from the femoral vein, and an inflow cannula was inserted into the right atrium from the right jugular vein. A Swan-Ganz catheter inserted into the outflow cannula led it to the pulmonary artery under blood pressure monitoring only. A Sarns' centrifugal pump was used as a blood pump. We applied this system to biventricular failed hearts supported by a left ventricular assist device. We could increase cardiac output from 53.3 +/- 31.8 to 77.8 +/- 31.7 ml/min/kg, and mean aortic pressure from 43.5 +/- 12.3 to 57.5 +/- 11.2 mm Hg with RAWT. The right ventricular unloading effect of RAWT was not disturbed by regurgitation through the pulmonary or tricuspid valve.

Animals↗