No abstract

We studied 279 patients who underwent mitral valve replacement at the Department of Thoracic and Cardiovascular Surgery, Hyogo College of Medicine, between November 1973 and December 1998. The patients were divided into two groups based on the type of replacement valve (154 patients in the biological xenograft group and 125 patients in the mechanical valve group), and the long-term results were compared. Clinically satisfactory results were obtained in both the biological xenograft group and the mechanical valve group according to the surgical results, long-term survival, and incidence of prosthetic valve endocarditis. At 15 years, fewer patients in the mechanical valve group than in the biological xenograft group were free of bleeding events (92.5 +/- 3.7% vs 100% P < 0.05). At 15 years, the biological xenograft group was lower than the mechanical valve group with respect to freedom from thromboembolism (72.2 +/- 4.6% vs 93.5 +/- 3.6% P < 0.01), freedom from valve failure (22.0 +/- 5.2% vs 87.0 +/- 4.1% P < 0.005) and freedom from cardiac events (16.5 +/- 3.9% vs 47.2 +/- 14.5% P < 0.01). Though it has previously been suggested that biological xenografts used in mitral valve replacement do not need anticoagulation, the current study suggests the need for anticoagulation with the use of biological xenografts. Mechanical valves require close monitoring of anticoagulation, but their use has decreased the incidence of valve failure and thromboembolism, as compared with the use of biological xenografts. Therefore, mechanical valves are currently the preferred choice for mitral valve replacement. We believe that biological xenografts are indicated only for the older patient (> or =65 years).

Lipoma in the ventricular septum is very rare. Our review of the English literature revealed that our case is the sixth of removal of lipoma in the ventricular septum. A 60-year-old male was admitted because a mass in the ventricular septum was found incidentally in abdominal CT taken following type B hepatitis. CT scanning of the heart showed 2 cm diameter of tumor in the ventricular septum. The tumor had very low radiodensity, so it was thought to be identical to fat tissue. The tumor was more clearly visualized by MR imaging and the signal intensity was high on the T1-weighted image. The tumor was suspected to be lipoma. The intraoperative histological diagnosis showed the tumor was lipoma. The tumor adhered strictly on the myocardium of the septum, and it was located near the left anterior descending coronary artery. It could not completely resected, in these reasons. Postoperative course was uneventful, and echocardiogram taken 9 months after the operation showed no evidence of enlargement of the residual tumor. It is necessary to follow-up rigidly for the potential of enlargement of the residual tumor.

We encountered a 75-year-old man who complained of exertional dyspnea. An echocardiographic examination showed aortic regurgitation and a tumor in the left ventricular outflow tract. Under complete extracorporeal circulation, we surgically made an incision of the ascending aorta with a slight thickening of the aortic valve and an enlarged annulus. After excising the aortic valve, an examination of the subvalvular region revealed mitral valve-like tissue extending from the annular region of the right coronary cusp to the ventricular septum, while the chordae tendinae was attached to the septum. This issue was excised, and the aortic valve was replaced with a 27-mm SJM valve. The postoperative course was uneventful, and the patient was discharged in good condition on postoperative day 30. An accessory mitral valve is extremely rare. Since this indication for surgical treatment is associated with congenital heart disease or a left ventricular outflow tract obstruction, most patients are young. Our patient had no associated cardiac anomalies and no pressure gradient attributable to a left ventricular outflow tract obstruction. This accessory mitral valve was discovered during aortic valve replacement surgery. To our knowledge, our patient is the oldest reported with an accessory mitral valve to have undergone a surgical resection.

We evaluated 30 patients who required hemodialysis (HD) before open heart surgery between January 1990 and September 2003. The patients were divided into 2 groups according to surgical procedure: 20 patients underwent coronary artery bypass grafting (CABG group: 14 men and 6 women, mean age, 63 years) , and 10 patients underwent valve replacement (VR group : 6 men and 4 women, mean age, 56 years). The mean duration of HD in the CABG group was significantly shorter than that in the VR group (67 months: 121 months, j=0.02). The actual survival rate was calculated by Kaplan-Meier's method. No patient was lost to follow-up. There were 3 hospital deaths in the CABG group (cerebral infarction, arrhythmia, and mediastinitis), and 2 hospital deaths in the VR group (gangrenous cholecystitis and sepsis). There were also 5 late deaths in the CABG group (acute subdural hematoma, pneumonia, AMI, heart failure and gastric cancer) and 4 deaths in the VR group (uterus cancer, 2 intracerebral hemorrhages and PVE). All cardiac event deaths in the CABG group had undergone CABG only with vein grafts. The 4-year actuarial survival rates were 56% (n=5) in the CABG group with a mean follow-up period of 29 months (max 156 months), and 47% (n=3) in the VR group with a mean follow-up period of 35 months (max 131 months). There are 3 points to improve the prognosis of open heart surgery in hemodialysis patients: control of postoperative infection in both groups, prevention of cardiac events in the CABG group and careful anticoagulation therapy in the VR group.