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Biomedical subjects

Y Shimazaki

Publications and source records attributed to Y Shimazaki.

At least 199 records · Page 11Linked to original sources
PubMed1986

[Follow-up study of atrial fibrillation associated with mitral stenosis after D-C cardioversion following open mitral commissurotomy].

We studied cardiac rhythm in 167 patients with mitral stenosis following open mitral commissurotomy in the last 7 years. After surgery 76 patients (72%) out of 106 patients who presented atrial fibrillation before surgery were reverted back to sinus rhythm by D-C cardioversion. Forty-three patients (41%) maintained sinus rhythm at the time of discharge from hospital, and 30 patients (28%) maintained it for 2.5 years (average) after surgery. The actuarial maintenance rate of sinus rhythm was 50 + 11% 7 years after surgery in these 43 patients. Ninety-three% of the 30 patients who reverted to and maintained sinus rhythm improved to class I (New York Heart Association criteria), whereas 47% of the 78 patients who retained atrial fibrillation remained in class II or III after surgery. In 30 patients who reverted back to sinus rhythm and maintained it late postoperatively, the preoperative duration of atrial fibrillation was up to 5 years, and 35% of the patients had had atrial fibrillation for more than 1 year. Also, in 40% of these 30 patients, the preoperative cardiothoracic ratio was more than 60%. Therefore, in the patients who reverted to atrial fibrillation immediately after surgery, secondary D-C cardioversion should be performed under stable hemodynamic conditions 10 to 14 days after surgery, even if their preoperative duration of atrial fibrillation was more than 1 year or their preoperative cardiothoracic ratio was more than 60%.

Adult↗
PubMed1985

Management of large aortopulmonary collateral arteries in patients with ventricular septal defect and pulmonary atresia: simultaneous ligation through median sternotomy during intracardiac repair.

Nine consecutive patients with ventricular septal defect (VSD) and pulmonary atresia associated with large aortopulmonary collateral arteries underwent primary repair with simultaneous ligation of these collateral arteries. The patients ranged from 1 year to 20 years old (average, 8.0 years). The average number of large aortopulmonary collateral arteries was 1.9 per patient. Arborization abnormality was found in 5 patients. The aortopulmonary collateral arteries were reached solely through a median sternotomy, with dissection of the posterior pericardium or anterior mediastinal pleura before or after the initiation of cardiopulmonary bypass. The immediate postoperative peak pressure ratio between the right and left ventricles was higher in patients with an arborization abnormality, but all ratios ranged from 0.60 to 0.87. There was 1 operative death. Postoperative transcatheter embolization for a residual large aortopulmonary collateral artery was required in 1 patient and pulmonary infarction of mild degree developed with spontaneous recovery in another. These results indicate the usefulness and safety of simultaneous ligation of large aortopulmonary collateral arteries through median sternotomy, even with an associated arborization abnormality.

Adult↗
PubMed1985

Right and left ventricular volume characteristics in children with transposition of the great arteries after Mustard's procedure.

With use of biplane cine-angiocardiograms, the measurements of right and left ventricular volume were determined in 11 children with transposition of the great arteries following Mustard's procedure. Right ventricular end-diastolic volume (RVEDV) ranged from 124 to 264 percent of the normal right ventricular volume with an average of 188 +/- 40 (SDM) percent, and left ventricular end-diastolic volume (LVEDV) ranged from 57 to 181 (122 +/- 43) percent of the normal (p less than 0.01, vs. RVEDV). Right ventricular ejection fraction (RVEF) ranged from 0.26 to 0.66 (0.42 +/- 0.11), and left ventricular ejection fraction (LVEF) ranged from 0.51 to 0.79 (0.66 +/- 0.09) (p less than 0.001, vs RVEF). Left ventriculography showed a deviation of the interventricular septum toward the left ventricle in patients with simple transposition of the great arteries not associated with left ventricular hypertension. The left to right ventricular systolic pressure ratio ranged from 0.22 to 1.02 (0.48 +/- 0.28), and the left to right ventricular end-diastolic volume ratio ranged from 0.43 to 1.00 (0.63 +/- 0.18). There was a high correlation between the left to right ventricular systolic pressure ratio and the left to right ventricular end-diastolic volume ration (r = 0.94, p less than 0.001). The left to right ventricular systolic pressure ratio also correlated well with the right ventricular ejection fraction (r = 0.90, p less than 0.001). Deviation of the interventricular septum was considered to result in a diminished ejection fraction of the right ventricle, in patients with simple transposition of the great arteries not associated with left ventricular hypertension, after Mustard's procedure.

Cardiac Volume↗
PubMed1985

Right ventricular function after extracardiac conduit repair for tetralogy of Fallot. A comparison among surgical approaches.

Right ventricular volume measurements and hemodynamic studies were performed in 20 patients after total correction of tetralogy of Fallot. There were 6 patients with an extracardiac conduit and Hancock xenograft (G-1), 8 with an outflow tract patch (G-2) and 6 without or with a minimal right ventriculotomy and repair of pulmonary valve (G-3). The age at the time of operation was over 3 years in each patient and averaged 5 +/- 2 (mean +/- SD) years. Right ventricular systolic pressure averaged 81 +/- 22, 55 +/- 22 and 58 +/- 30 mmHg in G-1, G-2 and G-3, respectively. Right ventriculography showed no contraction of the right ventricular free wall at the anastomosis to the conduit and poor contraction around the anastomosis in G-1. The right ventricular enddiastolic volume index (RVEDVI) was 114 +/- 31, 155 +/- 57 and 115 +/- 28 ml/m2 in G-1, G-2 and G-3, respectively. The right ventricular ejection fraction (RVEF) was 0.42 +/- 0.11 in G-1, 0.53 +/- 0.04 in G-2 (p less than 0.05, vs G-1) and 0.57 +/- 0.04 in G-3 (p less than 0.02, vs G-1). Pulmonary regurgitation was evident in 17 patients, and RVEDVI correlated well with degrees of pulmonary incompetence. Fourteen patients in G-2 and G-3 were divided into G-A and G-B to evaluate right ventricular function with or without pressure overloading of the right ventricle. G-A consisted of 7 patients with a right ventricular systolic pressure of more than 50 mmHg (74 +/- 26) and G-B of 7 patients with a value less than 50 mmHg (39 +/- 4). There was no difference in RVEDVI and RVEF between G-A and G-B. RVEF was significantly lower in G-1 than G-A (p less than 0.02) and G-B (p less than 0.05). These results suggested that an extracardiac conduit with Hancock xenograft reduced the contraction of the right ventricular free wall and induced a depressed right ventricular pump function in patients with a high right ventricular pressure.

Bioprosthesis↗
PubMed1984

Long-term results of open mitral commissurotomy for mitral stenosis with severe subvalvular changes: a ten-year evaluation.

Out of 212 patients undergoing open mitral commissurotomy for mitral stenosis from January, 1972, to December, 1981, 53 patients had extremely severe subvalvular changes. In this study, we evaluated postoperative results in these 53 patients. There were 2 operative deaths (3.8%) and 1 late death (1.9%). Of the 50 surviving patients, 34 (68%) were in New York Heart Association Class I and 13 patients (26%) were in Class II, postoperatively. Three patients (6%) required reoperations an average of 5 years 5 months because of the progression of residual mitral regurgitation. The actuarial rate of freedom from mortality and reoperation was 78.6% at 10 years after operation. When anticoagulant therapy was not given, no patient had thromboembolic complications. Postoperative hemodynamic studies demonstrated that mean diastolic gradients across the mitral valve were 5.30 +/- 1.25 mm Hg (standard deviation) at rest and 9.50 +/- 5.13 mm Hg during exercise. Calculated mitral valve areas were 1.86 +/- 0.48 cm2 at rest and 1.88 +/- 0.51 cm2 during exercise. There was no evidence of any adverse effects of mild to moderate valve calcification. It is concluded that for a follow-up period as long as 10 years, the stenosed mitral valve with greatly advanced subvalvular deformities can be salvaged with low mortality, low incidence of reoperation, and acceptable valve function even when such deformities are associated with mild to moderate calcification.

Blood Pressure↗
PubMed1984

The natural history of isolated congenital pulmonary valve incompetence: surgical implications.

The natural history of isolated congenital pulmonary valve incompetence has been determined by actuarial and parametric techniques from 72 cases collected from the literature. Symptoms developed within 20 years in 6% (CL 4% to 9%) of the patients and within 40 years in 29% (CL 22% to 36%). The hazard function of the development of symptoms demonstrates a risk increasing in time, particularly evident after 40 years. Death followed the appearance of symptoms after an average of 39 months in 3 patients who died. The surgical implications as regards the use of transannular patches and valveless extracardiac conduits are discussed.

Adolescent↗
PubMed1984

Postoperative changes of pulmonary vascular resistance in patients with complete atrioventricular canal defect. Relation to the age at primary repair.

The postoperative changes of pulmonary vascular resistance (PVR) of two age groups of children with complete atrioventricular canal (CAVC) were compared. Patients were divided by age at the time of primary repair; Group-1 (G-1, n = 4) with age below 2 years (average 13.8 mo.) and Group-2 (G-2, n = 5) with age over 2 years (average 44.0 mo.). All except one were Down's syndrome. Preoperatively, pulmonary to systemic resistance ratio (Rp/Rs) were 0.87 +/- 0.50 in G-1 and 0.41 +/- 0.13 in G-2 (n.s.), and postoperative study (average 6.5 mo.) showed no significant falls in Rp/Rs in both groups. However, G-2 showed significantly lower Rp/Rs postoperatively (0.79 +/- 0.19 in G-1 vs 0.27 +/- 0.12 in G-2, p less than 0.05). Mean pulmonary artery pressure (mPA) showed significant fall after surgery in only G-2 (66.8 +/- 6.6 to 31.8 +/- 11.6 mmHg, p less than 0.005). Anatomically, type-A showed better postoperative change in mPA compared to type-C. This study summarized the early progression of pulmonary vascular obstructive disease with poor postoperative improvement even the primary repair was done before 2 years of age. The less advanced pulmonary vascular disease in G-2 might have some relations to the natural selection of the disease.

Age Factors↗