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Biomedical subjects

C Oyama

Publications and source records attributed to C Oyama.

At least 55 records · Page 3Linked to original sources
PubMed1983

An improved method for transseptal left ventricular catheterization.

It is difficult to perform a retrograde left ventricular catheterization in patients having an aortic valve replacement. An improvement of the conventional transseptal catheterization (Brockenbrough method) led to a better success rate of catheterization. The fulcrum of the improved catheter was located 7 cm from the tip. Its curvature was approximately 270 degrees. Its tip was bent inward to form a pig-tail shape to prevent myocardial injury. This catheterization was performed 33 times in 32 patients. A 97% success rate was achieved. An exercise loading test was performed with a bicycle ergometer while this catheter was maintained in the left ventricle of a patient placed in a supine position. The catheter was well retained in the left ventricle and produced a minimal number of arrhythmias during exercise. The modification of this catheter has proved to be a better method of left ventricular catheterization in patients with an aortic valve replacement.

Adult↗
PubMed1983

Reversibility of the left ventricular function after aortic valve replacement for aortic regurgitation.

Ten patients with aortic regurgitation underwent aortic valve replacement using a Björk-Shiley valve prosthesis. They ranged from 27 to 58 years of age. The studies were centered around the postoperative hemodynamics, especially concerning the function of the left ventricle during a follow-up period which averaged about 8 months. The left ventricular end-diastolic volume (LVEDV) returned to the normal range, and the muscle mass of the left ventricle decreased remarkably after surgery. The ejection fraction and mean velocity of the circumferential fiber shortening both increased up to the normal range. The left ventricular end-diastolic pressure exhibited normal values with a decrease of the LVEDV. The depressed left ventricular function was largely reversible after surgery.

Adult↗
PubMed1982

Surgery for ascending aortic aneurysm with aortic regurgitation.

We reviewed 22 consecutive patients undergoing surgery during 13 years from 1968 to 1981 for ascending aortic aneurysms associated with aortic regurgitation due primarily to idiopathic medionecrosis resulting in annuloaortic ectasia. Chronic aortic dissection was accompanied in 45% of the patients. The operative period was divided into 2 stages, the first from 1968 to 1976, and the second from 1977 to 1981. In the earlier period, the operative mortality was 42%, and it improved significantly to 0% (p less than 0.05) in the later period. The reasons for improved surgical results are 1) the employment of the Bentall operation with some technical modifications and 2) the use of better myocardial protection method with cold potassium cardioplegia. The postoperative hemodynamic and clinical improvements were significant. The left ventricular improved toward normal (p less than 0.05 and p less than 0.001). Operative survivors showed a clinical improvement from NYHA class 3 to 1.3 on an average. The actuarial survival rate at 6 years after operation was 64.3% in the entire series, and 71.1% in patients with the Bentall operation. In patients with type I aortic dissection, a false lumen remained patent after operation and may progress to cause late morbidity or mortality. Surgery should be performed earlier than aortic dissection takes place whenever feasible. The Bentall operation can now be performed with a low risk, and can improve the clinical and hemodynamic states and very possibly prolong the longevity of the patients.

Adult↗