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Biomedical subjects

Y Orime

Publications and source records attributed to Y Orime.

At least 73 records · Page 4Linked to original sources
PubMed1993

Baylor Gyro Pump: a completely seal-less centrifugal pump aiming for long-term circulatory support.

A seal-less centrifugal pump aiming for long-term circulatory support has been developed. In this model, shaft seals that cause thrombus formation and blood leakage were eliminated. A brushless direct current motor was incorporated as a driving unit, and pivot bearings were used to support the impeller. With reference to its motor-driven system, this pump was named the M-Gyro Pump. The first model (M1) yielded an index of hemolysis of 0.005 g/100 L using bovine blood and demonstrated satisfactory performance as a right heart assist for 2 days (4 L/min, 60 mm Hg, 1,800 rpm). The second model (M2) has been developed for left heart assist by employing a stronger motor. The pump capacity was improved to 6 L/min against 240 mm Hg at 1,800 rpm, but significant heat generation was observed. By optimization of motor efficiency, the M2 model can be improved to meet the requirements of a pump for left heart assist.

Animals↗
PubMed1993

Development of the Baylor-Nikkiso centrifugal pump with a purging system for circulatory support.

The Baylor-Nikkiso centrifugal pump is a magnetically coupled system with a V-ring seal separating the pump and the actuator chamber. To prevent thrombus formation behind the impeller and to extend the life of the pump to 2 weeks of continuous operation, we incorporated a purging chamber behind the V-ring seal. An external pump connected to this purging chamber infused fluid at a constant rate to wash the shaft-seal area. To evaluate the effectiveness of the purging system, we have carried out biventricular bypass experiments using calves. The purging system was successful in reducing the level of thrombus formation after 2 weeks of operation. The results of these studies confirmed that the Baylor-Nikkiso centrifugal pump with this purging system is suitable for at least 2 weeks of continuous operation as a circulatory support system.

Animals↗
PubMed1993

[Simultaneous operation of Cabrol's operation and sternal turnover with rectus abdominal flap].

We performed simultaneous operation of sternal turnover and Cabrol operation for a 28-year-old man, who had 3rd grade funnel chest and annuloaortic ectasia with 3rd grade aortic regurgitation. We think when both annuloaortic ectasia and funnel chest are indicated for operation, simultaneous operation is to be considered and the combination of Cabrol operation and sternal turnover with rectus abdominal flap is the best procedure.

Adult↗
PubMed1992

New sequential synchronized driving system of intraaortic balloon pumping and left ventricular assist device: influence on endocardial viability ratio and renal blood flow in their combination.

Intraaortic balloon pumping (IABP) and left ventricular assist devices (LVAD) have shown remarkable progress individually, but how to combine them is still unknown. A new sequential synchronized driving system was developed to control concomitant use of IABP and LVAD, and then its hemodynamic effectiveness was evaluated in swine, especially on endocardial viability ratio (EVR) and renal blood flow. This system (pulsatile bypass pump-delay divide system, PBP-DDS) made it possible to change the driving phase of IABP and LVAD easily. In 12 swine, IABP and LVAD were set up, and these devices were driven in the following 5 modes with the PBP-DDS: mode I, IABP alone; mode II, LVAD alone; mode III, IABP + LVAD (same timing); mode IV, IABP (early diastole) + LVAD (late diastole); and mode V, LVAD (early diastole) + IABP (late diastole). EVR was increased more markedly by combined use of both IABP and LVAD (modes III, IV, and V) than by individual drive, but there was no significant difference among these modes. On the other hand, renal blood flow was decreased so dramatically by the same timing optimal counterpulsation method of mode III that it was thought to be harmful for renal function. But, the delay divide combination method of modes IV and V resulted in no change in the renal circulation. So, it was concluded that this delay divide combination mode appeared to be a more promising support to both failed heart and renal circulation.

Animals↗
PubMed1992

Versatile one-piece total artificial heart for bridge to transplantation or permanent heart replacement.

A versatile, one-piece total artificial heart (TAH) system that can be driven by either an electromechanical acutator (EM-TAH) or a pneumatic source (P-TAH) has been developed. The common units for both TAHs are the conically shaped left and right pusher-plate-type pumps (63 ml SV) that sandwich a thin centerpiece (18 mm) having a respective actuator. The EM actuator, mounted in the middle of the centerpiece, consists of a direct-current brushless motor and a roller screw while the pneumatic actuator consists of a low-pressure air source. The outer diameter of the pumping unit is 97 mm with its central thickness being 82 mm; overall volume is 510 cc. The TAH is operated in the left master alternative ejection mode with the left pump fill signal. High-flex-life Hexsyn rubber is used as the diaphragm, and the blood-contacting surface is coated with dry gelatin. The TAH can provide 3-8 L/min flow with a preload of 1-10 mm Hg against 100 mm Hg afterload. Anatomical fit of the pumping unit has been demonstrated in the pericardial space of 26 heart transplant recipients with average body weight of 78 kg. To date, 2 P-TAH and 4 EM-TAH (1 week) implantations were performed in 80-100 kg calves demonstrating excellent anatomical fit, controllability, and biocompatibility. This versatile TAH is suitable for a bridge to transplantation or permanent heart replacement.

Animals↗
PubMed1992

[Long-term patency of aorto-coronary saphenous vein grafts].

One hundred eighty-two cases with 814 aorto-coronary saphenous vein grafts were studied according to coronary risk factors (smoking, hypertension, hyperlipidemia, diabetes mellitus, obesity and family history). The patency rates of all cases were as follows, early-term (within one year after operation): 92.3%, mid-term (within 5 years after operation) 80.7%, long-term (more than 5 years after operation): 66.0%. Coronary risk factors have great influence upon the mid- and long-term patency, especially upon the latter. The long-term patency rate of the grafts complicated with hyperlipidemia was 57.4% and that without hyperlipidemia was 81.8% (p less than 0.01). Hyperlipidemia, complicating 55.5% of all cases, was one of the most influential factors on the patency and also the most difficult one to be controlled. In the United States and Europe, many cases were complicated with hyperlipidemia, and it was considered that the poor patency of the saphenous vein grafts in those countries was due to this fact. Pathological studies revealed that hyperplasia of intima and media, characteristics of venosclerosis, appeared frequently in the saphenous vein grafts having more than three risk factors, and that the factors had effect not only upon arteries but also upon veins. So we conclude that saphenous vein grafts are the materials of good long-term patency, and that the control of the risk factors, particularly hyperlipidemia, is the key to improve the patency.

Adolescent↗
PubMed1992

[Surgical techniques of ventricular assist device].

Since October 1982 to April 1990, we had 16 ventricular assist device (VAD) cases in our institute. Using this VAD system that was produced by Nippon Zeon company, surgical techniques for cannulation and de-cannulation could be made very easily, and connection between cannulae and pump also could be performed quickly. In this article, the actual surgical techniques and the know-how were illustrated in detail. If this techniques can be more accustomed, the clinical results of VAD cases will be improved.

Cardiac Catheterization↗
PubMed1992

[Right-sided patent ductus arteriosus with a right aortic arch and right descending aorta].

We experienced an extremely rare anomaly, i.e. right-sided persistent ductus arteriosus with a right aortic arch and right descending aorta. Reviewing the literature, we found only two cases clinically reported in Japan as far as we know. The diagnosis was established by angiography and MRI. We treated the patient successfully through right thoracotomy.

Aorta, Thoracic↗
PubMed1990

[Effectiveness and limitations of IABP or LVAD in right ventricular dysfunction].

IABP and well functioning left ventricular assist device for a failing left ventricle have potential for altering the loading condition of the right heart. Depending on the extent of myocardial damage and the pulmonary vascular resistance, IABP and LVAD can have different degree of hemodynamic effect on the right ventricle. We examined 20 clinical cases who required IABP support to wean from cardiopulmonary bypass. In 10 cases (group I), CVP rose up above 20 cmH2O within 12 hrs of post operative period. In another 10 cases (group II), CVP rose less than 20 cm H2O. Then we compared hemodynamic change (m-PAP, PVR, CVP, PAWP, CI and RVSWI) between two groups until 72 hrs of post operative period. No significant differences were noted in PVR and CI between two groups, but CVP, m-PAP, PAWP and RVSWI were markedly higher in I group. Reduction of RV afterload produced with an IABP may probably be due to degree of recovery of failing left ventricular function. It is though that IABP has less favorable effect on right ventricular in the cases whose CVP elevate above 20 mmH2O within 12 hrs after operation than in those with CVP below 20 cmH2O. Clinical studies were made on 4 cases with biventricular failure in our experiences of 8 LVAD cases (LV aneurysmectomy + VSP closure, MVR + AVR + CABG + LV aneurysmectomy, CABG + LV aneurysmectomy and MVR + CABG). LVAD seems to have more beneficial effect on RV afterload, than IABP right ventricular dysfunction, however, is likely to continue in the cases whose CVP elevates above 30 mmH2O even if LVAD is used.

Adult↗
PubMed1989

[Surgical treatment of the prosthetic valves in reoperation].

Surgical treatment and problems in patients required reoperation for malfunctioning prosthetic valves are reviewed in our institute. The cinefluoroscopy and pulse doppler echocardiography were helpful for diagnosis of artificial valve dysfunction. In recent two decades valve replacement were performed in 382 cases and number of re-implanted valve were 469. Among them the cases of reoperation were 21 and reimplanted valves were 25 (5.6%); 4.7% in aortic, 5.0% in mitral, 6.7% in tricuspid position. Three cases of those patients had three operations. Main causes of reoperation were primary tissue failure in Carpentier-Edwards porcine xenograft (6 cases, 23%) and cloth wear in Starr-Edwards ball valve (9 cases, 38%) and thrombosis in St. Jude Medical bi-leaflet valve (3 cases, 15%). In most cases St. Jude Medical valve were chosen for the alternative prosthetic valve in reoperation. We applied IABP support to seven patients for severe low cardiac output syndrome after the operation and overall mortality was 24% in reoperation. It concluded that St. Jude Medical valve may be most reliable because of low incidence of postoperative complication in our institute.

Adult↗
PubMed1989

[The results of surgical treatment of post-infarction left ventricular aneurysms].

The surgical results of post-infarction left ventricular aneurysmectomy have been evaluated in 24 patients approximately 1 year after operation. In 20 patients coronary artery bypass grafting (CABG) was also carried out. In 8 patients mechanical circulatory assist such as intra-aortic balloon pump (IABP) or left ventricular assist device (LVAD) was undertaken for the purpose of weaning from cardiopulmonary bypass. Postoperative left ventricular function, such as ejection fraction and cardiac index, and classification of the New York Heart Association were improved significantly after aneurysmectomy. However, postoperative improvement of these parameters was not remarkable in cases of poor preoperative left ventricular function. Preoperative left ventricular function revealed to be poor in multiple vessel disease, and concomitant coronary artery bypass grafting with aneurysmectomy can be performed with good long-term results and significant improvements of postoperative cardiac function. In patients that had showed the end-diastolic perimeter more than 40% and the shortening rate of transverse axis at the left ventricular base less than 20%, postoperative improvement of cardiac function revealed unsatisfactory. Mechanical circulatory assist showed lifesaving effect, but in cases that required IABP or LVAD postoperative cardiac function has not improved significantly.

Adult↗
PubMed1989

[Multiple organ failure following open heart surgery in adults].

The cases multiple organ failure (MOF) which occurred post-operatively following open heart surgery in adults were studied on a pre and post-operative hemodynamics. Post-operative low cardiac output syndrome (LOS) was thought to result in decreased renal and hepatic perfusion with subsequent ischemic damage to these organs. Therefore, to management MOF, we have to prevent post-operative LOS, for example, administration of cathecholamine and vasodilator, and early clinical application of IABP and ventricular assist device (VAD). In a post-operative hemodynamics, the cases of severe right ventricular failure tend to have more protracted MOF. It was though that MOF could be minimized with shortened cardiopulmonary bypass duration, and early application of assisted circulation.

Adult↗
PubMed1989

[Clinical experience for ventricular assist device].

We began applying of our VAD system clinically in 1982 and have subsequently obtained good results. The first case treated with the VAD returned to normal life. In a total of 70 cases of clinical applications this system there has been instance of apparatus dysfunction. Confirming the reliability and safety promised by the results of biological experiments. Here, we report the results of clinical application of the system in a total of 61 cases between August, 1985 and March, 1989. The following conclusions were reached: 1) Satisfactory weaning and survival rates were obtained i.e. 18 cases out of 61 cases (30%) survived over one month and 13 cases (21%) are currently surviving, even in elderly patients of 60 years of age or older. 2) The weaning rate and survival rates were good after approximately 1 week of support. Detailed evaluation of the recovery of the heart and functions of other major organs has led to the conclusion that the results can be improved further when the weaning period is carefully determined. 3) With regard to surgical factors, good findings were obtained when the artificial heart-lung bypass time was less than 6 hours. The VAD can be used in the early stages without vainly attempting weaning from the artificial heart-lung bypass. 4) There were no mechanical problems with the hardware of the blood pump drive assembly, etc., or noteworthy side effects.

Aged↗