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Biomedical subjects

A Mizuhara

Publications and source records attributed to A Mizuhara.

At least 19 recordsLinked to original sources
PubMed1998

[Intraoperative assessment of the ascending aorta by echogram during the CABG operation for the prevention of cerebral infarction].

While coronary artery bypass grafting operations (CABG), we started to use the echogram to evaluate the ascending aorta intraoperatively from December 1993. During a period from January, 1990, to June, 1995, 379 patients were treated with CABG. Intraoperative echogram was used in 127 cases (group I) and 252 cases unused (group II). The sites of the aorta for evaluation were following: site of cannulation, aortic clamping, and proximal anastomosis respectively. Depending on the echographical findings the operative procedures were changed as required. The incidence of postoperative cerebral embolism in group I was 0.8% (one patient) and in group II, 2.4% (6 patients). Although no significant difference was found in the cohort, rate of incidence in the group II was high. There were 4 cases who had significant atheromatous lesions clearly evaluated by echogram, which were not detected by palpation. We conclude that the intraoperative assessment of the ascending aorta by echogram is beneficial in prevention of cerebral infarction.

Aged↗
PubMed1996

[Tricuspid valve replacement by right thoracotomy with minimal dissection in reoperations].

We report two cases of tricuspid valve replacement for tricuspid valve insufficiency as reoperations following mitral valve replacement through midline sternotomy. A right thoracotomy was used to approach the tricuspid valve. To avoid the risk of cardiac laceration, cardiopulmonary bypass was instituted after cannulation of the femoral artery and of superior vena cava through right atrium with balloon caval occlusion and inferior vena cava through the femoral vein with balloon caval occlusion. Without aortic cross clamping under mild hypothermia, right atriotomy was performed through adherent parietal pleura, pericardium, and right atrial wall without dissection. Tricuspid valve was replaced utilizing the bioprosthetic valve with good clinical results. These new measures were expeditiously carried out without dissection of the heart, which has been deemed to be the risk of reoperations.

Bioprosthesis↗
PubMed1996

[The protective effect of hypothermia in a new transient cerebral ischemic model of the rat--A 31P magnetic resonance spectroscopy in vivo study].

The energy state and intracellular pH of the rat brain during and after transient cerebral ischemia was measured by the method of 31P magnetic resonance spectroscopy in vivo for the purpose of the evaluation of the protective effect of hypothermia. The rat's chest was opened and the bilateral subclavian arteries were ligated. The transient cerebral ischemia was induced by occlusion of the bilateral cerebral arteries using the balloon occluders. The rat's brain was cooled to 20 degrees C by the surface cooling using the ice bags and was heated to 37 degrees C in the control group, respectively. The animal's temperature was adjusted and regulated by a water blanket placed under the animal's body. After 30 min cerebral ischemia, the level of phosphocreatine (PC) was decreased to 58 +/- 4% versus to 36 +/- 4%, 20 degrees C versus 37 degrees C, respectively (p < 0.01). ATP was decreased to 73 +/- 5% versus 52 +/- 4% (< 0.01). Intracellular pH was decreased from 7.23 to 6.48 at 20 degrees C, from 7.22 to 6.08 at 37 degrees C (p < 0.01). After 60 min ischemia, PC was decreased to 52 +/- 5% versus to 33 +/- 6%, 20 degrees C versus 37 degrees C (p < 0.01). ATP was decreased to 62 +/- 6% versus 36 +/- 6% (p < 0.01). At 37 degrees C either PC or ATP was not recovered to the pre-ischemic level. Intracellular pH was decreased to 6.38 at 20 degrees C, to 5.80 at 37 degrees C (p < 0.01). It is concluded the hypothermia saved the high energy phosphates and keeps intracellular pH high and this beneficial effects contribute the brain protection during cerebral ischemia.

Animals↗
PubMed1996

[Replacement of descending thoracic aorta using open proximal anastomosis under hypothermic circulatory arrest].

Open proximal anastomosis under hypothermic circulatory arrest was applied to eleven consecutive patients with descending aortic diseases. These patients included five aortic dissections and six thoracic aortic aneurysms. Fourth and 7th intercostal spaces were opened by left posterolateral thoracotomy. Cardiopulmonary bypass was established by right atrial drainage via femoral vein and main pulmonary artery. Arterial blood was perfused via femoral artery. The descending aorta was opened under hypothermic circulatory arrest with anal temperature of 20 degrees C, and the anastomosis of the proximal site of the graft was performed with bloodless field. After the proximal anastomosis was finished, the main graft was clamped and perfused via the branch of the graft. The distal anastomosis was performed during circulatory arrest of the lower body. Mean circulatory arrest time of the upper body was 31 min, and that of the lower body was 37 min. Nine of the patients arrive without any major complications, but two of them died due to postoperative low cardiac output syndrome and postoperative pneumonia. Open proximal anastomosis under hypothermic circulatory arrest may be useful for the replacement of the diseased descending aorta due to dissection or aortic aneurysm with mural thrombi because of the advantage of non-clamping anastomosis with bloodless surgical field.

Adult↗
PubMed1996

[A case report of St. Jude medical aortic valve prosthesis thrombosis].

We report a case of successful semi-emergent redo aortic valve replacement for thrombosed prosthetic valve. Patient was a 59-year-old male who had undergone aortic valve replacement of St. Jude Medical prosthetic valve and open mitral commissurotomy 14 years ago. He suffered from pneumonia with hemosputum and admitted a neighbor hospital. But he was reffered to our medical center because of progressing dyspnea. We found the immobility of one of the leaflets of the prosthetic valve by cinefuluoroscopy. He was also diagnosed as prosthetic valve thrombosis and mitral valve restenosis using ultrasonic echocardiography. The thrombi were developed on the hinge of one of the leaflets, and they might be formed during the time he had got inappropriate anticoagulation therapy at the former hospital. We emphasise the importance of strict anticoagulation control for the patients valve replaced.

Aortic Valve↗
PubMed1995

Left ventricular end-systolic volume index in patients with ischemic cardiomyopathy predicts postoperative ventricular function.

BACKGROUND: We investigated the usefulness of the preoperative left ventricular end-systolic volume index (LVESVI) as a predictor of postoperative ventricular function. METHODS: We retrospectively reviewed the records of 310 patients who underwent coronary artery bypass grafting and identified 20 patients with ischemic cardiomyopathy with a preoperative ejection fraction less than 0.30. We determined the preoperative and postoperative ejection fraction, LVESVI, and left ventricular enddiastolic volume index using biplane left cineventriculography. Patients were divided into groups depending on whether their preoperative LVESVI was less than 100 mL/m2 (group A, n = 10) or greater than 100 mL/m2 (group B, n = 10). RESULTS: The mean ejection fraction increased significantly after coronary artery bypass grafting in group A from 0.25 +/- 0.05 to 0.40 +/- 0.09 (p < 0.01), but did not change significantly in group B (0.26 +/- 0.05 versus 0.23 +/- 0.06). The mean LVESVI decreased significantly in group A from 83.2 +/- 13.7 to 61.7 +/- 20.4 mL/m2 after operation (p < 0.05), but did not change significantly in group B (124.7 +/- 21.0 versus 121.5 +/- 37.6 mL/m2). In group B, 4 patients had signs of congestive heart failure during the follow-up period and had to be rehospitalized. CONCLUSIONS: The mean ejection fraction improved significantly after coronary artery bypass grafting in patients with a preoperative LVESVI less than 100 mL/m2, despite the presence of a global left ventricular ejection fraction less than 0.30. Our results suggest that the preoperative LVESVI predicts the postoperative status and left ventricular function in patients with ischemic cardiomyopathy.

Aged↗
PubMed1995

Evaluation of the antithrombogenicity of a new microdomain structured copolymer.

A new antithrombogenic material was studied, fluorine-acryl-styrene-urethane-silicone (FASUS) copolymer, the theoretical basis of which attributed to its hydrophilic and hydrophobic microdomain structure. In this series of experiments, the blood compatibility of this copolymer was evaluated in vitro and ex vivo. For the in vitro evaluation, a whole blood clotting test and the microsphere column test were performed. For the ex vivo evaluation, two series of shunt tests in rabbits were performed, one was the arterioartery (A-A) shunt model, and the other was the arteriovenous (A-V) shunt model. The antithrombogenicity was assessed by measuring the shunt obstructive time in the A-A shunt experiment. The A-V shunt experiment was assessed by measuring the circulating platelet counts, platelet aggregability, activated partial thromboplastin time (APTT), and prothrombin time (PT). In the whole blood clotting test, FASUS revealed the significantly longer blood clotting time than that of the control glass tubings (19.7 +/- 1.0 versus 6.5 +/- 0.7 min, p < 0.001). In the microsphere column test, the coated group had a 30% reduction of the platelet number in the eluted blood in contrast with a marked decrease of 70% in the control group (p < 0.05). In the ex vivo A-A shunt experiment, the occlusion time for the FASUS-coated group was significantly longer than that of the control (109.7 +/- 17.3 versus 3.0 +/- 0.4 min, p < 0.05). The A-V shunt experiment showed that the FASUS copolymer suppressed the decrease in platelet counts and tended to improve prolonged APTT compared with that of the control. Clinically, in 25 patients, we placed coated FASUS copolymer into the cannulas for use in percutaneous cardiopulmonary support (PCPS) procedures. There was no evidence of thrombus on the blood contacting surface and no thromboembolism in major organs clinically or upon postmortem examination. In summary, this new copolymer may be effective in preventing thrombus formation in vitro, ex vivo, and in clinical situations.

Aged↗
PubMed1995

[Coronary artery perforation after directional coronary atherectomy (DCA)].

Directional coronary atherectomy (DCA) was performed on a 51-year-old man with unstable angina due to a 90% stenosis of the proximal side of the left anterior descending artery (LAD). A coronary angiography after the DCA showed the coronary artery perforation communicating with the pericardial space. He suffered cardiac tamponade and cardiogenic shock, and was taken to the emergent surgical intervention. The both side of the perforation was ligated to control active bleeding and coronary artery bypass grafting to the distal portion of the LAD was performed. It is stated that the incidence of tamponade resulting from vessel perforation after DCA is extremely rare.

Angina, Unstable↗
PubMed1995

[Clinical significance of selective cerebral perfusion with cold blood on the brain protection].

In 42 patients with thoracic aortic disease, a selective cerebral perfusion with 16 degrees C cold blood was applied for the brain protection during the repair of the thoracic aorta. The surgical repair consisted of the replacement of the ascending aorta (9 cases), the ascending aorta and aortic arch (12 cases), the aortic arch (18 cases), and the aortic arch and descending aorta (3 cases). Twenty-two patients of them (52%) required emergency surgery and four patients died due to postoperative complications including visceral organ ischemia (2 cases) and multiple organ failure (2 cases). The mortality rate of this group was 18.2% (4/22 cases). In elective surgical classes, one patient died due to intraoperative coronary embolism. The mortality rate of this group was 5.0% (1/20 cases). No postoperative obvious brain defect was observed except one old patient (85-year-old female) with ruptured aortic arch who already had the brain infarction preoperatively. She died due to multiple organ failure with unconsciousness. Other patients including the patients with long cerebral perfusion (> 180 min) recovered well and returned to normal daily life. The selective cerebral perfusion with cold blood was easy to prepare and demonstrated the superb efficacy of brain protection in the patient.

Adult↗
PubMed1995

[Cerebral infarction after the cardiovascular operation].

From January, 1990 through July 1994, 615 adult patients were undergone cardiovascular operation under the cardiopulmonary bypass. Sixteen patients were suffered perioperative cerebral infarction. The etiology of the cerebral infarction was evaluated on the pre and postoperative brain CT findings by the neurologists. In the 283 coronary artery bypass operations, 4 patients suffered watershed infarction (WS) and 4 cerebral embolism. In the 252 valve operations, one WS and one embolism. In the 80 thoracic aortic operations, 5 WS and one embolism, respectively. The risk factors of WS were the elderly, emergency, the longer operative period, and the longer cardiopulmonary bypass period. The risk factor of the embolism were male, preoperative cerebral infarction, the calcified finding of the ascending aorta by the chest CT. It is important to take preventive strategies against the watershed infarction.

Adult↗
PubMed1994

Assessment of aortic disease using three-dimensional CT angiography.

The recently developed technique of three-dimensional CT angiography (3D-CTA) was applied to 68 patients with aortic disease. These patients were examined using a unique method of data collection: a helical scanner with continuous tube rotation and continuous table feed. The scanner was used in conjunction with administration of dynamic intravenous contrast material to enhance the vascular image. The group of patients included 35 with aortic dissection, 19 with true thoracic aneurysms, and 14 with abdominal aortic aneurysms. Three-dimensional evaluation was achieved in all patients with no complications. Surgical intervention was used in 45 patients with aortic dissections and aortic aneurysms, and 44 of these patients (98%) survived and were discharged. Preoperative 3D-CTA findings were quite similar to intraoperative findings, and were useful in determining operative procedures. Rapid and accurate assessment of aortic disease was achieved by 3D-CTA. Three-dimensional CT angiography can play an important role in the preoperative assessment of aortic dissections and aortic aneurysms leading to successful surgical treatment.

Adult↗
PubMed1994

[A case report of tricuspid valve valvoplasty for tricuspid endocarditis].

A successful repair of tricuspid valve insufficiency due to endocarditis related to VSD is reported. Combined quadrangular resection and repair of anterior leaflet, pericardial patch plasty of anterior-septal commissure, Carpentier ring annuloplasty and VSD closure was performed with good clinical results.

Adult↗
PubMed1994

[Reoperation for recurrent chondrosarcoma of the pulmonary trunk].

A 71-year-old woman who had progressive dyspnea and edema two years after resection of a pulmonary trunk chondrosarcoma was diagnosed as severe obstruction to the pulmonary trunk due to the recurrent tumor. Magnetic resonance examination following the intravenous administration of Gd-diethylenetriamine pentaacetic acid (DTPA) revealed striking contrast enhancement within the lesion of the pulmonary trunk sarcoma. At reoperation, the recurrent mass was identified within the same site of the pulmonary trunk and total resection of the tumor and replacement of the pulmonary trunk with prosthetic graft was performed utilizing a cardiopulmonary bypass. There have been very few reports on replacements of pulmonary trunks for pulmonary artery sarcomas. It is reported that the prognosis of the pulmonary trunk sarcoma is extremely poor, however, this patient has undergone thoracotomies twice within two years and continued to be symptom-free without distant metastatic lesions.

Aged↗
PubMed1994

[Preoperative assessment of aortic dissection by three-dimensional CT angiography].

In 21 patients with aortic dissection including 12 patients with acute aortic dissection, aortic lesions were evaluated preoperatively by newly developed three-dimensional CT angiography (3 D-CTA) using helical scan CT. Rapid and safe three-dimensional evaluation of aortic dissection was achieved with no complications. Three-dimensional structure of aortic dissection was well reflected in the image of 3D-CTA. Preoperative three-dimensional evaluation was useful to determine and proceed the operative procedure for the repair of aortic dissection. All patients were alive and results of surgical treatments were excellent. Intimal flaps and entries were visualized by multiple threshold display (MTD) method of 3D-CTA. Multiple threshold display method is an important three-dimensional reconstructive method and 3D-CTA may be a new useful and powerful diagnostic modality for aortic dissection.

Adult↗
PubMed1994

[Evaluation of the addition of counterpulsation to the partial left ventricular-femoral bypass for limitation of evolving myocardial infarction].

The effect of adding counterpulsation to a partial left ventricular bypass was evaluated in a canine model of acute myocardial ischemia by using a myocardial staining method. To establish a left ventricular bypass, a catheter consisting of bypass tube (90 cm in length and 15 Fr in inner diameter) and an accompanying intraaortic balloon as a single apparatus (Integrated Cardioassist Catheter; ICAC) was introduced into the left ventricle via the abdominal aorta. The left ventricular bypass was adjusted to 1 L/min. with or without counterpulsation with the aid of a centrifugal pump and IABP console. The use of the ICAC that provided pulsatile left ventricular bypass tended to raise the mean aortic pressure and cardiac output. Reduction of the tension time index was noted with the use of the ICAC in contrast to the control. And increment of the DPTI/TTI ratio was observed with the use of the ICAC in contrast to the control and partial left ventricular bypass alone. While the percentages of the region at risk were similar [17.3 +/- 9.5% (control), vs. 16.4 +/- 3.4% (partial left ventricular bypass alone) vs. 16.9 +/- 5.2% (ICAC)], the percentages of infarct sizes were reduced due to the use of counterpulsation. [61.9 +/- 12.2% (control), vs. 57.5 +/- 3.9% (partial left ventricular bypass alone) vs. 16.8 +/- 6.0% (ICAC)]. These results revealed that the addition of counterpulsation alleviates afterload reduction to the partial left ventricular bypass and was more beneficial to the reduction of the infarct size than partial left ventricular bypass alone.

Animals↗
PubMed1994

[Aortic valve replacement for a patient associated with severe liver cirrhosis].

A 55-year-old man who had severe aortic regurgitation by bacterial endocarditis associated with severe alcoholic liver cirrhosis admitted in our hospital for the treatment of congestive heart failure. ICG15' score was 45.0% and redox tolerance test score was 0.38 x 10(-2). Preoperative hepatic function state was estimated as Child B. Preoperative preparation for the liver cirrhosis was done with FFP and glucagon insulin treatment. Aortic valve replacement was performed under the pulsatile high flow and high perfusion pressure during cardiopulmonary bypass. Post operative course was fair and he discharged.

Aortic Valve↗