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Biomedical subjects

S Miki

Publications and source records attributed to S Miki.

At least 181 records · Page 10Linked to original sources
PubMed1989

[Successful mitral valve repair and myocardial revascularization in an infant with anomalous origin of the left coronary artery from the pulmonary artery].

An 8-month-old girl of anomalous origin of the left coronary artery from the pulmonary artery associated with severe mitral regurgitation underwent radical operation. She had been in serious cardiac and respiratory failure. Aorto-left coronary arterial continuity was established by intrapulmonary arterial tunnel using Takeuchi's technique. Mitral annulus was plicated by modified Kay's technique. Post-operative course was uneventful.

Coronary Vessel Anomalies↗
PubMed1988

Myocardial dysfunction and ultrastructural alterations mediated by oxygen metabolites.

The direct effect of oxygen metabolites was studied on isolated perfused rat hearts. Superoxide anion (O2-.) and hydrogen peroxide (H2O2) were generated by adding purine (2.3 mM) and purified xanthine oxidase (0.06 U/ml) to Krebs-Henseleit buffer (pH 7.4). Xanthine oxidase was added to the purine-containing perfusate either near the aorta (group A, which gave H2O2 less than 10 microM) or at a distant point from the aorta (group B, which gave 250 to 300 microM H2O2). The generation rate of O2-. was 31.7 +/- 1.0 nmol/ml/min in the experimental conditions. Contractile function, tissue adenosine triphosphate (ATP), and ultrastructure were not affected in group A. In contrast, hearts in group B showed marked decrease in contractility (+dP/dt) to 24.4 +/- 4.3% of control values. ATP levels were also markedly reduced from control values of 23.4 +/- 0.7 to 7.4 +/- 0.7 mumol/g dry tissue. Ultrastructure in group B hearts revealed "wavy" and disintegrated sarcolemma, depletion of glycogen deposits, and swelling and disruption of mitochondria. Release of the thiobarbituric acid reactive products including malondialdehyde was significant in the effluent (1.68 +/- 0.17 nmol/min/g wet tissue). These changes were almost completely prevented by catalase, but not by superoxide dismutase and deferoxamine. Moreover, exogenous H2O2 perfusion (300 microM) showed results similar to group B hearts. These observations suggest that H2O2 plays a major role in the injury. O2- does not appear to damage hearts directly, although it is important as a precursor of H2O2 and other radical species including hydroxyl radical.

Adenosine Triphosphate↗
PubMed1988

Mitral valve replacement with preservation of chordae tendineae and papillary muscles.

An operative technique for mitral valve replacement (MVR) with preservation of the chordae tendineae to the anterior leaflet as well as the posterior leaflet is reported. This technique consists of the division of the anterior leaflet into anterior and posterior segments, the shifting and reattachment of the divided segments to the mitral ring of the respective commissural areas, and the use of a low-profile bileaflet prosthetic valve. A comparison of left ventricular function data between patients having operation with this technique and those having operation with the conventional method of MVR revealed significantly better improvement in cardiac index (p less than 0.06), left ventricular end-systolic volume index (p less than 0.05), and left ventricular ejection fraction (p less than 0.10) in the former group. Left ventricular wall motion improved in the anterolateral (p less than 0.01) and apical areas (p less than 0.02) in patients operated on with our technique. Maintenance of continuity between the mitral annulus and papillary muscles is expected to have a beneficial effect on postoperative left ventricular performance in spite of increased afterload.

Adult↗
PubMed1988

Intractable hemolysis caused by perivalvular leakage following mitral valve replacement with St. Jude Medical prosthesis.

Nine patients with intractable hemolysis caused by perivalvular leakage following mitral valve replacement with a St. Jude Medical prosthesis are presented. All patients had dark-colored hemoglobinuria, which appeared from 1 day to 44 days after the operation, with moderate or severe hepatorenal insufficiency. One patient died of multiorgan failure. The other 8 patients underwent reoperation, and all survived. Reoperation revealed that all leakages were tiny and had no adverse effect on hemodynamics. In all the patients having reoperation, hemoglobinuria disappeared immediately after the procedure. Surface-scanning electron microscopy of the sewing cuff of the St. Jude Medical prosthesis revealed the rough surface structure of the sewing ring. Because of this irregular, shaggy surface structure, greater shearing forces against erythrocytes can be generated when there is perivalvular leakage.

Adolescent↗
PubMed1988

Evaluation of corrective surgery for tetralogy of Fallot from late results by multivariate statistical analysis.

From 1966 to 1985, 469 pediatric patients with the tetralogy of Fallot (mean age, 4.9 years) were corrected (hospital mortality 11.9%). There were 9 late deaths (1.9%). In 186 patients, hemodynamic studies were performed 2-14 years postoperatively (mean age, 10.4 years). An increased cardiothoracic ratio (CTR) of 60% or more was found in 42 patients with impaired postoperative physical activity. The factors affecting the late results were investigated in relation to CTR by the quantification method of multivariate analysis. As for the enlarged CTR, pulmonary regurgitation was more of a contributing factor than pulmonary stenosis. In pulmonary regurgitation, the pulmonary artery area index (PAAI) and reconstruction of the right ventricular outflow tract (RVOT) were highly significant factors. For pressure gradient, the VSD site was the most significant factor. These analyses suggest that preservation and/or reconstruction of the pulmonary valve, or trans-annular patching with the necessary minimal area for the RVOT (PAAI) not to exceed 4 cm2/m2 at the time of operation is important for satisfactory late results.

Adolescent↗
PubMed1988

Massive systemic venous thrombosis after Fontan operation: report of a case.

A 7 year old boy with single ventricle with pulmonary stenosis underwent a modified Fontan procedure. He had a very stormy postoperative course complicated by continued pleural effusion, hepatomegaly, and chylothorax. He eventually died after an atrial septum reopening. At autopsy, massive thrombi were found in the inferior vena cava, right atrium, and pulmonary artery. This complication was probably due to multiple factors, but a routine anticoagulation therapy may be required after Fontan procedure.

Cardiac Surgical Procedures↗
PubMed1988

Long-term results of aortic valvuloplasty for aortic regurgitation associated with ventricular septal defect.

Long-term results in 64 patients who underwent aortic valvuloplasty for aortic regurgitation associated with ventricular septal defect are presented. The average age of the patients was 10.2 years and the average cardiothoracic ratio was 0.57 at the time of operation. The average degree of aortic regurgitation, as classified by Sellers, was 2.7. The type of ventricular septal defect was subpulmonic in 31 patients, perimembranous in 20, and was a total conal defect in five patients. Valvuloplasty was performed at one end of an aortic cusp in 23 patients, at two ends in 33, at three ends in six, and at four ends in two patients. There was one operative death (1.6%). The follow-up period was 447.7 patient-years, and there were no late deaths. The actuarial survival rate was 98.3% at 5, 10, and 15 years. Postoperative cardiac catheterization was performed in 40 patients. Valvuloplasty failure was defined as the presence of a cardiothoracic ratio greater than 0.6, a loud regurgitant murmur (Levine grade 3/6 or greater), moderate or severe aortic regurgitation (Sellers grade 3 or 4), or the necessity of reoperation. There were 17 patients whose valvuloplasty failed. The freedom from valvuloplasty failure was 74.2% at 5 and 10 years and 55.3% at 15 years. Eight patients underwent reoperation because of residual aortic regurgitation, and all survived. The freedom from reoperation was 90.1% at 5 years, 80.5% at 10 years, and 63.7% at 15 years. Multiple regression analysis revealed that older age, a greater cardiothoracic ratio, perimembranous ventricular septal defect, and multiple valvuloplasties were significant contributing factors for residual regurgitation after aortic valvuloplasty.

Actuarial Analysis↗