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Biomedical subjects

R Yozu

Publications and source records attributed to R Yozu.

At least 91 records · Page 5Linked to original sources
PubMed1982

Hexsyn trileaflet valve: application to temporary blood pumps.

A trileaflet valve, compression molded of Hexsyn rubber, was evaluated as a component in temporary blood pumps. A pair of valves was integrated into an LVAD which was tested in vitro and in vivo. The valve's hemodynamic performance was satisfactory and the blood compatibility was excellent in a three-week, in vivo experiment conducted to demonstrate performance in a short-term application. Hexsyn, which has excellent properties and produces high quality, complex components with ease of fabrication, offers a potential for low-cost blood pump valves.

Alkenes↗
PubMed1979

Ascending aorta-supraceliac abdominal aorta bypass: successful removal of an infected graft in the descending thoracic aorta.

An infected graft and a mycotic pseudoaneurysm were successfully resected by employing an ascending aortasupraceliac abdominal aorta bypass graft in a 19-year-old man. He had formerly undergone graft replacement surgery for traumatic aneurysm of the descending thoracic aorta, with the aid of a temporary external bypass graft. After this first operation, the patient had suffered from septicemia due to Psudomonas aeruginosa, which resulted in formation of mycotic pseudoaneurysms at the distal anastomotic site of the prosthetic graft and at both stumps of the formerly employed external bypass graft.

Adult↗
PubMed1979

New surgical method for repair of anomalous left coronary artery from pulmonary artery.

A new surgical method for repair of anomalous origin of the left coronary artery from the pulmonary trunk is described. The principle of the proposed technique is to transmit the oxygenated blood to the anomalous left coronary artery through surgically created aortopulmonary window and the internal tunnel created in the main pulmonary trunk. A 2-year-old boy in whom this anomaly was associated with mitral regurgitation caused by papillary muscle dysfunction was successfully treated by this new surgical method, and the deformed mitral valve was concomitantly replaced by a Hancock porcine xenograft.

Angiocardiography↗
PubMedDate not supplied

Development and clinical application of a next generation implantable echocardiography probe for monitoring cardiac function under assisted circulation after open heart surgery.

Post-operative cardiac function generally is monitored by electrocardiography, invasive measurement of blood pressure, and determination of hemodynamic variables, such as pulmonary pressures and cardiac output with a Swan-Ganz catheter. In recent years, transesophageal echocardiography has been introduced into clinical use, but it is not a popular method of monitoring for various reasons, including the difficulty of application to unconscious post-operative patients. Since 1991, we have been developing a small implantable echocardiography probe. This probe was tested in 15 patients who underwent open heart surgery for severe left ventricular hypofunction, and its clinical utility was demonstrated. No deaths occurred in this series. The implantable echocardiography probe allowed post-operative cardiac function to be monitored in real-time. The ejection fraction, the cardiac output, the status of valves after valvuloplasty, the presence of cardiac tamponade, and other variables could be assessed. The echocardiography probe can be positioned at any site where specific information is desired during surgery. It can be inserted as easily as a pericardial drain tube and is removed in the same manner when no longer necessary. This probe has the potential to be useful for monitoring patients on assisted circulation after cardiac surgery.

Assisted Circulation↗
PubMedDate not supplied

Feasibility study of vascular-endoscopic valvuloplasty. Using a laser and flexible endoscope.

Percutaneous balloon valvuloplasty is generally accepted, but post procedural complications limit its efficacy and reduce long-term success. To eliminate these risks, the authors explored the feasibility of cardioscopy guided percutaneous laser valvuloplasty in an experimental setting. The combined working model consisted of a separate balloon tipped thin fiber optic endoscope, laser balloon catheter, and a Nd-YAG laser transmitter. A porcine pulmonary valve was used as our in vivo target of laser ablation in a beating heart. Under general anesthesia, the endoscopic catheter is delivered into the pulmonary valve area through either the internal jugular or femoral vein under fluoroscopy. Positioning the pulmonary apparatus coaxial to the endoscopic visual field by manipulation of the catheter allowed for targeting and ablation of the commissure of the pulmonary valve under endoscopic view through the balloon filled with saline solution. The ablation energy was 15-30 W, 0.5-1.0 sec, and 2,000-3,000 J total. The animal was then killed and histopathologic study of the ablated area was done. The commissure of the pulmonary valve was smoothly ablated in 4 cases, and the entire ablation procedure was successfully witnessed through endoscopy. The authors encountered some difficulty in laser targeting, limitations to the endoscopic field of vision, and difficulty in holding the position of the apparatus in the beating heart. These are the barriers to overcome for future clinical application of this procedure. However, these results indicate the clear possibility of future use of cardioscopy guided percutaneous laser valvuloplasty in a clinical setting.

Animals↗
PubMedDate not supplied

A single skeletal muscle powered ventricle that assists both systemic and pulmonary circulations.

Extraaortic counterpulsation using skeletal muscle powered ventricles (SMPVs) has been studied mainly for the purpose of assisting the systemic circulation. The purpose of this study was to investigate the possibility of assisting both the systemic and pulmonary circulations using a single SMPV. An SMPV that counterpulses the systemic circulation is placed beside the right atrium (RA) or the right ventricle (RV), the former after procedures such as a Fontan operation, and the latter in cases of biventricular failure. Because the SMPV dilates passively during cardiac systole, it is designed to press the RA or the RV directly from outside. This study is a preliminary report, and only the ability of a specially constructed SMPV to dilate was assessed. Using seven dogs with heart failure, the SMPV dilated with an internal pressure of 88 mmHg and 1.0 cm, while the volume inside increased by 10.8 ml. From these results, it is suggested that the SMPV has enough dilating power to press the RA or to assist the RV while counterpulsing the systemic circulation.

Animals↗
PubMedDate not supplied

A new endo aortic occlusion balloon for limited access cardiac surgery: development and clinical evaluation.

In recent years, minimally invasive cardiac surgery (MICS), or limited access cardiac surgery, has been presented as a promising operative procedure. We developed a new balloon device that is inserted directly into the ascending aorta to stop the heart during limited access cardiac surgery. The balloon has a three lumen structure: balloon lumen port, cardioplegia/vent lumen port, and aortic root lumen port. This direct EAC balloon catheter, designed to be inserted directly into the ascending aorta, is different from the Heartport system. The Heartport EAC balloon catheter is inserted into the aorta via an artery in the lower limb, making lower limb arterial disease a key concern. Our Direct Endo Aortic Clamp (EAC) balloon overcomes this problem. The device was clinically used in seven cardiac cases. All patients were discharged within 5 postoperative days, confirming the utility of the device.

Aorta↗