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Biomedical subjects

R Yozu

Publications and source records attributed to R Yozu.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Indication for coronary revascularization in aortic surgery].

UNLABELLED: In order to know how to treat the coronary artery disease in scheduled aortic surgery for aortic aneurysms, a prospective study started about ten years ago using routine coronary angiography (CAG). Thoracic aortic aneurysm (TAA): CAG was performed in 73 among 143 patients and 18 had significant coronary artery stenoses (CAD), 3 of whom had angina. Concomitant CABG was performed in 2 of 4 patients requiring coronary revascularization (CR) to prevent intraoperative myocardial ischemia. Complications due to CAD were experienced in the 2 patients without CR despite of angina, while patients without angina or with CR had no complication. Abdominal aortic aneurysm (AAA): Seventy six among 150 patients had CAG, and CAD was found in 38. CR was indicated to 5 of 7 patients with angina. Complications occurred in 2 patients who had not CR in spite of angina. Patients without angina had no complication. CONCLUSION: 1) Patients who had angina are at high risk for complications due to CAD. 2) Patients with angina and necessity of cardiac arrest during aneurysmectomy should have coronary revascularization prior to aneurysmectomy. 3) Patients without angina are at low risk for myocardial ischemia in the perioperative period of aortic surgery.

Adult↗
PubMed1989

[A case of biventricular assist with centrifugal pumps after operation of ventricular septal perforation following acute myocardial infarction].

We applied biventricular assist using centrifugal pumps on a 64-year-old male who has undergone an operation against post-myocardial infarction with ventricular septal perforation. The pump flow was maintained at the level of 2.5 l/m2 in CI, and the pulse pressure 30 to 50 mmHg with IAPB. Complete hemostasis has been achieved prior to use heparin to control the patient's ACT around 200 sec. on the third pumping day. The patient's cardiac function improved in a few days at the beginning, but did not recover enough for weaning from the assist devices. He died on the 8th pumping day, and the autopsy revealed massive old myocardial infarction which is considered to be the major obstacle against the recovery of the cardiac function. There was no edema in any organs. Centrifugal pumps are very useful for ventricular assist in availability and in economy. Its efficacy is comparable with pulsatile ventricular assist devices especially when applied with IABP though there still exists controversy as for the superiority of pulsatile flow in ventricular assist.

Assisted Circulation↗
PubMed1989

[Surgical consideration of ruptured abdominal aortic aneurysms].

During the recent 18 and a half years, 30 cases of ruptured abdominal aortic aneurysm (including four cases of A-V fistula) were operated at Saiseikai Utsunomiya Hospital. In 26 cases, a conventional graft replacement was performed. In other four cases, axillo-bifemoral bypass (in the cases ruptured into the colon) or other methods were used. Overall operative mortality rate was 26.7%. However, during the last 9 years, operative results were improved (21.7%, 5 deaths out of 23 cases). Amount of intraoperative blood loss influenced the operative results greatly. Other operative risk factors included preoperative shock, preoperative severe cerebrovascular or cardiovascular complications, and postoperative thromboembolism. Factors of recent improvement in mortality included; establishment of emergency system which resulted in earlier operation after the patient's arrival at the hospital, use of occlusive balloon for bleeding control, heparin administration before the aortic clamp for preventing peripheral thromboembolism and introduction of autotransfusion system for reducing the amount of blood transfusion.

Adult↗
PubMed1989

[Biological versus mechanical valves in the mitral position].

The long-term late results of isolated mitral valve replacement before April 1981 were retrospectively evaluated in 54 patients receiving a Hancock valve (HX) with a total follow-up of 424 patient-years (py) and 37 patients receiving a Björk-Shiley valve (BS) with a total follow-up of 366 py. There was no significant difference in regard to preoperative age, cardiothoracic ratio, electrocardiogram, or New York Heart Association functional class between the two groups. All of the BS group and 43 of the HX patients received long-term anticoagulant therapy. No significant difference was notable between the two groups in hospital mortality. Actuarial survival rate excluding hospital deaths was 75.5 +/- 6.7% for the HX group, and 80.8 +/- 7.1% for the BS group at ten years (not significant). There was no significant difference between the two groups in overall incidence of thromboembolism (HX 1.4% py, BS 1.9% py), anticoagulant related bleeding (HX 0.5% py, BS 0.8% py), or endocarditis (HX 0.5% py, BS 0.3% py). Actuarial freedom from reoperation at ten years was 69.6 +/- 8.1% for the HX group, and 93.5 +/- 4.4% for the BS group (p less than 0.01). Event free survival excluding hospital deaths at ten years was 49.2 +/- 8.1% for the HX group, 70.6 +/- 8.3% for the BS group (p less than 0.05). We prefer a mechanical prosthesis except in patients over 65 years old, who have a short life expectancy, in whom anticoagulation is thought to be difficult, and who hope a biological valve.

Adult↗
PubMed1989

A clinical study of cerebral circulation during extracorporeal circulation.

The objective of this study is to clarify the relationship of cerebral blood flow to extracorporeal circulation flow and mean arterial pressure during nonpulsatile extracorporeal circulation under moderate hypothermia. Cerebral blood flow was determined by an argon saturation and desaturation method after that of Pevsner and colleagues with a mass spectrometer in 21 adult patients undergoing cardiac operations. Cerebral blood flow was 25, 33, 35, and 42 ml/100 gm/min, ranging from 19 to 50 ml/100 gm/min, at extracorporeal circulation flow rates of 40, 50, 60, and 70 ml/kg/min, respectively. Cerebral blood flow increased proportionally to extracorporeal circulation flow. Cerebral blood flow scattered almost transversely to mean arterial pressure and was 31 ml/100 gm/min in a hypotensive group (mean arterial pressure 34 to 50 mm Hg) and 34 ml/100 gm/min in another group (mean arterial pressure 51 to 94 mm Hg). Mean arterial pressure did not significantly influence cerebral blood flow. Cerebral oxygen consumption did not remarkably decrease and remained in the reasonable range when cerebral blood flow was 23 to 40 ml/100 gm/min. Subsequently, we assumed that the average cerebral blood flow value of 25 ml/100 gm/min at an extracorporeal circulation flow rate of 40 ml/kg/min also would be in the safe range. All of the patients are living without cerebral complications. We conclude that (1) cerebral blood flow was extracorporeal circulation flow dependent and (2) cerebral blood flow in the safe range was maintained even in the hypotensive range, provided the extracorporeal circulation flow rate was 40 ml/kg/min or higher.

Adolescent↗
PubMed1989

[Clinical usefulness of intraoperative color Doppler sonography in the operation of the dissecting aortic aneurysm].

Dissecting aneurysm of the aorta is a serious disease with a complex and wide range of morphology. Preoperative examinations such as echo, CT, and angiography, etc, have the limits in their respective capabilities and it is not always easy to say that the morphology is sufficiently elucidated. We have investigated clinical usefulness of this method in DAA under operation. In 10 cases of DAA, We were able to easily see the stereoscopic general image of the aorta including the bloodstream by the use of Doppler's tomography. During the operation of DAA, Doppler's tomography was very useful in determining detailed surgical procedure as well as in judging effects of the operation. In conclusion, intraoperative color doppler sonography is a valuable new tool to provide information which may significantly improve the surgical result in aortic dissection.

Adult↗
PubMed1989

[Surgical treatment of thoracoabdominal aortic aneurysms].

Between February, 1981, and April, 1989, 20 patients underwent surgical treatment of thoracoabdominal aortic aneurysms. Most of the patients were operated under temporary external bypass. For Group I and III aneurysms without reconstruction of renal arteries, a modified Crawford's graft inclusion technique was employed to shorten abdominal visceral ischemic time. This modification consists of (1) using adjuncts to perfuse the distal aorta during aortic clamp, (2) starting the first anasistomosis from the distal end of the graft, and (3) shifting the distal aortic clamp on the graft after completing the anastomosis in order to restore abdominal visceral circulation as soon as possible. For Group III and IV aneurysms with reconstruction of renal arteries as well as celiac and superior mesenteric arteries, a modified DeBakey's procedure was employed. This modification consists of (1) using the spiral opening method, (2) doing end-to-end anastomosis at the proximal aortic site, and (3) maintaining the circulation of abdominal organs and spinal cord by using adjuncts during the anastomosis of the proximal end. There were one operative death and two hospital deaths. Paraplegia developed in two cases, one of which was a ruptured case. Renal dysfunction was not found in any case. The survivors were followed from 5 to 103 months, and there was no late death. The results suggest that our modified procedures for thoracoabdominal aortic aneurysms are useful and reliable ones.

Adult↗
PubMed1985

Use of the anaerobic threshold for evaluating various total artificial heart control algorithms in calves.

In the total artificial heart (TAH) project, choosing the best control mode is an important factor in the design of a completely implantable TAH. Four different control modes for the TAH were evaluated in the same calf using the anaerobic threshold (AT) as an assessment of aerobic capacity, where AT was defined as the oxygen consumption (VO2) at which the relationship between blood lactate measurements and VO2 became nonlinear during progressive treadmill exercise. This new approach tests the integrated response of the central, peripheral, and metabolic regulatory mechanisms to physiological workloads. Preliminary data showed AT in the left master alternatively ejecting mode to be slightly higher than in the other three modes.

Anaerobiosis↗
PubMed1985

A mathematical model to predict the optimal control mode for a pusher-plate total artificial heart (TAH).

Table I lists the physiological criteria for ranking each control mode (hemodynamic conditions assumed are listed in Figure 4). For each criteria, each mode was given a ranking of 0 to 3, with 3 the best. At the bottom of the table is the total of all criteria grades. The ranking from best to worst mode is in order: IND, LMA/LMS, Low FR/High FR, RMA/RMS. A discussion of Table I follows: FR is a reliable control mode and has been used extensively clinically, including the recent TAH human implants. The advantage of this mode is its simplicity: if the venous return is below pump capacity, then all incoming blood can be pumped out without any sophisticated controller. However, when the flow demand exceeds the pump capacity, HR must be increased. The ideal situation would be to set FR at one HR and %S, and leave these settings over the life of the recipient. However, a high HR like this would result in relatively high atrial pressures and low flow rates with respect to IND (as shown theoretically, in vitro, and in vivo). Although the patient would have a high maximum COR, the daily COR would be low, resulting in a relatively high AVO2 difference. Finally, FR lacks afterload sensitivity. RMA and RMS received the lowest grade of all modes. Because of the L-L shunt, the stroke length of these modes are smallest, and thus the CO curves and FPS are poorer than any other mode.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗