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Biomedical subjects

H Yoshizu

Publications and source records attributed to H Yoshizu.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Effects of superoxide dismutase administered by coronary sinus retroperfusion on ischemic reperfused canine heart].

The efficacy of superoxide dismutase administered using synchronized coronary venous retroperfusion (SRP) on the extent of myocardial reperfusion injury was studied. Eighteen mongrel dogs were divided into three groups. A control group (group A) consisting of six dogs was subjected to 90 minutes of acute myocardial ischemia via balloon occlusion of the left anterior descending coronary artery (LAD) followed by 6 hours of reperfusion following abrupt deflation of the balloon. In the second group (group B) consisting of six dogs, the LAD was occluded for 2 hours followed by 5.5 hours of reperfusion. In this group, SRP was applied for 30 minutes prior to full reperfusion. In the third group (group C) consisting of six dogs, balloon inflation and deflation was performed in the same manner as group B except the administration of 10 mg/kg of superoxide dismutase (SOD) using SRP. During the occlusion of LAD, severe ischemia was detected by blood flow measurement using color microsphere in all groups. After reperfusion regional blood flow expressed as the percent of preocclusion value in the subendocardial area in three groups were 25% (group A), 38% (group B) and 76% (group C), respectively. There were significant differences between the groups (p < 0.05). Left ventricular function was assessed as global ejection fraction. Although occlusion of the LAD resulted in a reduction of the left ventricular ejection fraction with a similar magnitude in all groups (A; 37 +/- 5%, B; 32 +/- 7%, C; 58 +/- 10%), there was an improvement in groups B and C during reperfusion (p < 0.05). Infarct size was assessed by triphenyl tetrazolium chloride staining.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Short-term treatment with synchronized coronary venous retroperfusion before full reperfusion significantly reduces myocardial infarct size.

The efficacy of short-term synchronized coronary venous retroperfusion (SRP) before full arterial reperfusion was studied in a canine model. A control group (n = 6) was subjected to 90 minutes of occlusion of the left anterior descending coronary artery, which was followed by 6 hours of reperfusion. In another group (n = 6) the left anterior descending coronary artery was occluded for 2 hours followed by 5.5 hours of reperfusion. In this group SRP was applied for 30 minutes before full reperfusion. Myocardial regional blood flow was measured with the use of colored microspheres. During occlusion of the left anterior descending coronary artery, there was severe myocardial ischemia in both groups. Blood flow in the subendocardial area was, however, significantly better in the SRP group (0.51 +/- 0.17 ml/min/gm after 3.5 hours of reperfusion) than in the control group (0.29 +/- 0.16 ml/min/gm) after 4 hours of reperfusion (p less than 0.05). Left ventricular function was assessed as global ejection fraction from a left ventriculogram. Ejection fraction was reduced during ischemia in both groups (control = 38% +/- 3%, SRP = 32% +/- 8%). This dysfunction remained after 4 hours of reperfusion. Infarct size was assessed by means of triphenyltetrazolium chloride staining. The myocardial area at risk was similar in the two groups (control = 33.1% +/- 5.3%, SRP = 30.6% +/- 6.5%). Infarct size, which was expressed as the percent of the area at risk, was significantly smaller in the SRP group (17.2% +/- 14.6%) than in the control group (36.0% +/- 8.1%; p = 0.0197).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Surgical reconstruction of an ascending aortic dissection in Takayasu's arteritis.

A 45-year-old Japanese woman with Stanford type A dissecting aortic aneurysm underwent a reconstructive operation on the ascending aorta. Histopathological diagnosis was Takayasu's arteritis in the chronic and inactive phase. It is very rare that a dissecting aortic aneurysm results from Takayasu's arteritis. Long-standing hypertension and fragility of the aortic media due to disruption of elastic fibers were suspected to cause dissection in the entire aorta in this case.

Aortic Dissection↗
PubMed1990

[Effective administration method of recombinant superoxide dismutase in acute myocardial ischemia and reperfusion].

To determine the efficacy of direct versus systemic administration of human recombinant superoxide dismutase (rt-SOD) in acute myocardial ischemia and reperfusion, the following experimental model was applied. Twenty-one dogs were subjected to 30 minutes normothermic global ischemia caused by the occlusion of the ascending aorta followed by 60 minutes reperfusion. To eliminate collateral blood flows during the ischemia, bipulmonary hilus were cross clamped. The dogs were randomly assigned to three groups: group A (n = 7), 12 ml of normal saline was injected through the aortic root into the coronary artery 1 minute prior to reperfusion, in addition to a 30 minute continuous infusion of 50 ml of saline into the cardiopulmonary bypass circuit beginning just after reperfusion; group B (n = 7), rt-SOD (10,000 U/kg) dissolved in 12 ml saline was administered by bolus injection through the aortic root and an additional 30,000 U/kg of rt-SOD dissolved in 50 ml of saline was injected into the cardiopulmonary bypass circuit as the same manner as the group A; group C (n = 7), the treatment was similar to the group B except the bolus injection of rt-SOD was into the cardiopulmonary bypass circuit. The left ventricular stroke work index (LVSWI) was determined by a right heart bypass technique and expressed as a percent recovery of pre-occlusion state. Morphologic structures were observed by the electron microscope. The coronary sinus blood was assessed for malondialdehyde (MDA) measured by TBA method and creatine phosphokinase (CPK). The percent of recovery of LVSWI after 60 minutes reperfusion was superior in group B (121 +/- 82%) than groups A (24 +/- 38%*, *p less than 0.05) and C (52 +/- 21%*). In group B, the myocardial cell structure had a normal appearance in most areas, but swollen mitochondria and disrupted myofibrils were observed in groups A and C. Serum MDA levels did not change in all groups. Increasing CPK levels after reperfusion were less in group b than group A. These results suggest that an adequate concentration of rt-SOD in the interstitial fluid or cell surface at the time of reperfusion may be required to prevent reperfusion injury.

Animals↗
PubMed1990

[Brachial plexus injury and fracture of the first rib as complications of median sternotomy].

In 192 patients following median sternotomy during from 1978 to 1988, we studied the incidence, cause, prognosis and correlation of brachial plexus injury and fracture of the first rib as complications of median sternotomy. Four brachial plexus injuries were identified, an incidence of 2.1%, seven first-rib fractures were identified, an incidence of 3.6% and one patient had both complications in this series. Symptoms of this patient were more severe and difficult to improve than those of patients without first-rib fracture. Stretching of the nerve by the displaced first rib, ischemia of the nerve by pressure on it, and direct injury by the fractured rib end are causes of the brachial plexus injury following median sternotomy. It is due to the difference of position of the fracture, the difference of direction and degree of the protrusion of the fractured rib end, whether presence or absence of the brachial plexus injury in patients with first-rib fracture.

Adolescent↗
PubMed1990

[Cardiac arrest episodes by cardiomyopathy following total pancreatectomy, a case report].

A 47-year-old man with advanced pancreatic carcinoma underwent total pancreatectomy with resection of the involved portal vein. His postoperative course was complicated by a couple of cardiac arrest episodes. The first episode occurred seven weeks after surgery during drip infusion of CDDP, and later on during the thirteenth week after surgery. There was no apparent cause for those episodes. On both occasions resuscitation was performed adequately. The second arrest was followed by deep inverted T waves on ECG, however, not by elevation of serum CPK-MB. Because of this, myocardial infarction was ruled out. The diagnosis of cardiomyopathy was made possible through the discovery on the echocardiogram of a hypertrophied left ventricle with thick interventricular septum. Then, on catheterization, myocardial squeezing in the left anterior descending coronary artery was noticed. Finally, histological findings concerning the biopsied cardiac muscle led to the same diagnosis. Cardiac arrest in this case seemed to be due to arrhythmia caused by cardiomyopathy. Echo cardiography should be routinely used as part of the examination prior to extended major surgery.

Cardiomyopathy, Hypertrophic↗
PubMed1989

[Surgical repair of vascular ring with aberrant brachiocephalic artery].

The vascular ring causes tracheal and esophageal compression and some cases need the surgical intervention. We report a rare case of vascular ring with aberrant brachiocephalic artery. A nine-month-old boy had suffered from progressing stridor and was admitted to our hospital due to the stridor. The digital subtraction angiography revealed the aberrant brachiocephalic artery which compressed the trachea from anterior aspect. The compression of the trachea was released by tacking forward the aberrant brachiocephalic artery to the sternum with the aid of two stitches. The postoperative course was uneventful. The stridor almost disappeared at one year after the operation.

Aorta, Thoracic↗
PubMed1985

[Effects of percutaneous transluminal coronary angioplasty on left ventricular function at rest and during exercise].

The effects of percutaneous transluminal coronary angioplasty (PTCA) on left ventricular function at rest and during stress test were examined. Effect of PTCA at rest We studied 10 patients who fulfilled the following criteria, 1) single vessel disease, 2) high grade stenosis in the left anterior descending artery, 3) successful PTCA, 4) no restenosis, 5) without electrocardiographic evidence of previous myocardial infarction, and 6) technically adequate left ventriculograms in both pre and post PTCA studies. Follow-up studies were done six months after PTCA. Filling fraction as an index of early diastolic function was significantly lower than that of normal controls. There were no significant changes in left ventricular end-diastolic pressure, peak dp/dt, negative peak dp/dt, ejection fraction, left ventricular systolic pressure/end-systolic volume, between pre- and post-PTCA studies. Filling fraction in a jeopardized area, which was supplied by the left anterior descending artery, increased significantly after PTCA. No significant change was observed in the inferior area. Effect of PTCA during stress test A contrast stress test in eight successful cases without restenosis was performed by injecting 0.7 ml per kilogram of contrast material (76% urografin) at a rate of 13 ml/sec into the left ventricle before and six months after PTCA. The left ventricular end-diastolic pressure increased to 20.1 +/- 3.8 mmHg during stress test before PTCA, and only to 14.3 +/- 5.3 mmHg after PTCA (difference highly significant). Before the procedure, negative peak dp/dt during stress test was 1782 +/- 358 mmHg/sec; it increased significantly to 2342 +/- 702 mmHg/sec after PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1984

Prolonged left ventricular dysfunction induced by sequential multifocal ischemic infarcts in dogs.

A method of creating multifocal ischemia in animals leading to left ventricular (LV) functional impairment is described. In a series of 10 mongrel dogs, electrodes were implanted in multiple branches of the coronary arteries. Subsequently, in seven animals, an 800-microA anodal current was applied for 3 h repeatedly over a span of 4-9 weeks. After current application, serum creatine kinase cardiac isoenzyme increased by 12.2 +/- 4.6 U/L (p less than 0.01) and ischemic electrocardiographic changes were consistently present. After an average of 10.7 current applications, all animals were tachypneic on mild exertion. Repeated measurement of LV function demonstrated a substantial reduction in cardiac reserve. No significant changes in three control animals were observed. The animals were sacrificed 80 days (range 49-108 days) after the initial current application. Presacrifice cineangiography and postmortem examination disclosed coronary artery occlusions, stenoses, recanalizations, and collateralization in the distributions expected on the basis of the time elapsed since electrode activation. In all cases, the myocardium exhibited diffuse fibrosis. This method reliably brings about multifocal myocardial ischemic changes in dogs and may provide a chronic LV failure model particularly suitable for the evaluation of LV assist systems.

Animals↗
PubMed1983

A method for generating obstructive thrombi in the coronary arteries of the conscious dog.

A technique for staging the generation of obstructive thrombi in the coronary arteries of conscious dogs is described. At thoracotomy, electrodes are placed in the lumina of coronary artery branches. When thrombus generation in proximity to the intraluminal electrode tip is desired, anodal current is applied to the exteriorised end of the electrode. In each of nine anaesthetised adult mongrel dogs two to seven intracoronary electrodes were implanted for a total of 35. One to 75 days later, 50 to 800 microA anodal current was applied to 16 electrodes for 30 min to 48 h. Upon autopsy, thrombi in various stages of organisation were found in proximity to the intracoronary portion of 15 electrodes. Six electrodes were found to be damaged or broken. In contrast, only four of the 13 control electrodes were sites of thrombus formation. In seven dogs tissue sections indicated either myocardial ischaemia or infarct in regions whose perfusion was blocked by thrombi. This method may provide for discretionary generation of intracoronary thrombi in the desired quantity, at the preferred site(s), at selected times of onset. Consequently, it offers the possibility of adjusting the onset, severity, and time course of myocardial ischaemia.

Animals↗