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Biomedical subjects

R Shirakura

Publications and source records attributed to R Shirakura.

At least 181 records · Page 10Linked to original sources
PubMed1987

Reconsiderations of indications for open mitral commissurotomy based on pathologic features of the stenosed mitral valve. A fourteen-year follow-up study in 347 consecutive patients.

From January 1972 to December 1984, 347 consecutive patients underwent open mitral commissurotomy for mitral stenosis. Commissurotomy was performed in 86% of 404 patients undergoing mitral valve operations for stenosis during the same period. These 347 patients had three different types of mitral stenosis: type I, mobile cusps without subvalvular changes (43 patients); type II, thickened cusps with subvalvular changes (210 patients); type III, rigid cusps with severe subvalvular changes (94 patients). Concomitant mild mitral regurgitation was seen in 87 patients (25.1%) and mild to moderate valve calcification in 61 patients (17.6%). There were eight early deaths (2.3%) and 12 late deaths (3.5%), yielding an actuarial survival rate of 94.6% (excluding early deaths) 14 years after operation. There were 17 reoperations (5.0%) The actuarial rates of freedom from reoperation were as follows: 83.8% at 14 years for the entire series; 73.5% for type I stenosis; 88.9% for type II; 84.0% for type III; 91.7% for mitral stenosis with calcification; 82.6% for stenosis without calcification; 90.6% for pure mitral stenosis; and 52.5% for stenosis combined with regurgitation (p less than 0.05). Postoperative effective mitral valve areas calculated according to the hydraulic formula were 2.52 cm2 (mean) at rest and 3.06 cm2 during exercise in six patients with type I stenosis, 2.21 and 2.48 cm2, respectively, in 10 with type II, and 1.85 and 1.87 cm2, respectively, in 14 with type III. Our data clearly demonstrated that open mitral commissurotomy provided excellent long-term results with acceptable valve function and a low incidence of reoperation in patients with pure mitral stenosis not combined with regurgitation, even when associated with severe subvalvular changes with or without mild to moderate valve calcification.

Adolescent↗
PubMed1986

Long-term results of direct-current cardioversion after open commissurotomy for mitral stenosis.

For a 7-year period, cardiac rhythm before and after surgery was determined in 106 patients with mitral stenosis presenting with atrial fibrillation (AF) who had undergone open mitral commissurotomy. Forty-three of the patients reverted to sinus rhythm (SR) after primary or secondary direct-current (DC) cardioversion after surgery and maintained it until discharge from hospital. Thirty patients maintained SR for 3 months to 7.2 years (mean 2.5 years) after surgery. The actuarial maintenance rate of SR was 50% 7 years after surgery in these 43 patients. The duration of AF, preoperative left atrial dimension by M-mode echocardiogram and pathologic classification of the mitral valve were factors supposedly influencing the maintenance of SR for a long period after DC cardioversion. In 30 patients who reverted back to SR and maintained SR late postoperatively, the preoperative duration of AF was up to 5 years, and 35% of the patients had had AF for more than 1 year. Also, in 40% of these 30 patients, the preoperative cardiothoracic ratio was more than 60%. It is concluded that if sinus rhythm is restored by DC cardioversion before discharge from hospital after open mitral commissurotomy, it has a 50% chance of being maintained for 7 years after surgery. Long duration of AF and large cardiothoracic ratio should probably not dissuade one from attempting secondary DC cardioversion in these patients.

Adult↗
PubMed1986

Optimum dose of cold potassium cardioplegia for patients with chronic aortic valve disease: determination by left ventricular mass.

Twenty-eight patients with chronic aortic valve disease and left ventricular (LV) hypertrophy who underwent aortic valve replacement were studied. Angiographically obtained LV mass ranged from 113 to 580 gm (average, 292 gm). In 14 patients, the LV mass per square meter of body surface area was 200 gm or more. Cold glucose-insulin-K+ cardioplegic solution was infused to obtain a myocardial temperature of less than 15 degrees C. The initial dose of cardioplegic solution was increased to as much as 25 mL per kilogram of body weight when LV hypertrophy was severe. The initial dose was standardized by LV mass and ranged from 1.0 to 3.6 ml/gm (average, 2.7 ml/gm). Postoperative peak levels of the myocardial-specific isoenzyme of creatine phosphokinase (CPK-MB) showed no significant relationship to aortic cross-clamp time, but were related significantly to LV mass (r = 0.457, p less than 0.02). The initial dose of cardioplegic solution per LV mass and the peak CPK-MB had an inverse relationship (r = -0.753, p less than 0.001). Also, peak CPK-MB was significantly lower in those patients with an initial dose of cardioplegic solution per LV mass of 2.5 ml/gm or more regardless of the size of the LV mass (300 gm or more and less than 300 gm) in spite of no significant difference in myocardial temperature. These results indicate that the dose determination of cardioplegic solution by LV mass seems desirable for patients with chronic aortic valve disease and LV hypertrophy even when myocardial temperature is monitored.

Adult↗
PubMed1986

Inferior vena cava thrombus after retroperitoneal lymphadenectomy for testicular tumor.

A rare case of a thrombus in the inferior vena cava (IVC) after retroperitoneal lymphadenectomy for a testicular tumor is reported. A computed tomograph performed after the operation incidentally showed a filling defect in the IVC. However, it was impossible to decide whether the defect was due to an ordinary or a neoplastic thrombus. For this reason, a thrombectomy was performed, and postoperatively it was diagnosed as an ordinary thrombus. The cause of thrombi found only in the IVC is reviewed and the indication for thrombectomy is discussed.

Adult↗
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

Use of the balloon catheter for distal occlusion of the aorta in prosthetic replacement of aortic arch aneurysms.

A balloon catheter was utilized to occlude the distal aorta during prosthetic replacement of an aortic arch aneurysm in 4 consecutive patients under conditions of separate cerebral and peripheral perfusion and deep hypothermia. All patients survived the procedure, and 3 were doing well 1 to 1.5 years following operation. One patient sustained a cerebral infarction and recovered with some sequent disability. The use of a balloon occlusion catheter allowed us to perform the operation through a median sternotomy only, and eliminated the procedure of pulmonary dissection for distal clamping and the risk of emboli. In addition, its use provided a relatively bloodless field and sufficient protection for organs in the lower body through adequate perfusion, even when their function was poor or when the distal anastomosis was prolonged. We realized improved surgical results in the treatment of aneurysms of the aortic arch.

Aged↗