Surgical treatment of degenerative mitral regurgitation

Between October 1965 and April 1975, mitral valve replacement was performed In 66 patients with myxomatous degeneration of the mitral valve (“floppy valve syndrome”). Operative mortality was 6 percent (four patients). Current evaluation was obtained for all patients; the average postoperative follow-up interval for surviving patients was 3.5 years (range 1 month to 9.9 years); the total duration of postoperative follow-up for all patients was 180 patient-years. Overall survival rates, calculated by the actuarial method, were 81, 68 and 50 percent, respectively, 1, 2 and 5 years after mitral valve replacement.Preoperative variables with a significantly adverse effect on patient survival included patient age greater than 50 years, New York Heart Association functional class IV, left ventricular end-diastolic pressure greater than 12 mm Hg and mean pulmonary arterial wedge pressure greater than 16 mm Hg. Support is advanced for the concept that mitral valve dysfunction associated with myxomatous degeneration constitutes a broad spectrum of clinicopathologic involvement. Acute clinical and hemodynamic deterioration may often occur in the setting of chronic mitral valve dysfunction. Postoperative mortality is directly related to preoperative functional disability and hemodynamic evidence of impaired left ventricular function. Consideration should be given to earlier operative intervention in patients with myxomatous mitral degeneration and mitral insufficiency before severe and probably irreversible impairment of ventricular function occurs.     

Patient-related risk factors as predictors of results following isolated mitral valve replacement

Results following isolated mitral valve replacement in 897 consecutive patients over a twelve-year period were analyzed with regard to the influence of various preoperative patient-related risk factors. Actuarial data analysis allowed definition of major preoperative, etiological, clinical, and hemodynamic correlates to both perioperative and long-term postoperative patient survival. Patient age below 60 years, preoperative New York Heart Association Functional Class of III or less, cardiac index greater than 2.0, and left ventricular end-diastolic pressure of less than 12 mm Hg were all highly significant correlates of improved perioperative as well as long-term patient survival. Patients whose predominant functional lesion was mitral insufficiency had only a 53% five-year survival (187 of 352 patients) following mitral valve replacement as opposed to 70% (521 of 745 patients) for those who had mixed or stenotic mitral lesions. Primary ischemic mitral dysfunction was associated with only 31% five-year survival (17 of 54 patients) after mitral valve replacement in contrast to 69% (480 of 695 patients) for patients with rheumatic mitral lesions. The presence of occlusive coronary artery disease coexisting with, but not the primary cause of, mitral dysfunction was associated with decreased perioperative and late postoperative survival. Results support both earlier operative intervention and wider use of associated procedures, ie, coronary bypass grafting, with mitral valve replacement. Recognition of major preoperative patient-related risk factors should enhance survival following this procedure.     

Correlative study of regional left ventricular histology and contractile function.

In 110 patients with documented coronary artery disease, transmural biopsy of the anteroapical region of the left ventricle was performed during aortocoronary bypass grafting. Biopsy specimens were semiquantitatively graded microscopically for myocardial fibrosis as an indicator of chronic ischemic damage. Preoperatively, systolic wall motion of the region from which the biopsy specimen was taken was semiquantitatively graded as showing normal motion, hypokinesia, akinesia or dyskinesia on ventriculography. Wall motion-histologic correlations, taking into account both electrocardiographic evidence of anterior infarction and ST-T abnormalities, were then established. Overall, there was fair agreement (72 percent) between functional and histologic assessment of the left ventricular region evaluated, both qualitatively (normal versus abnormal, 72 percent agreement) and quantitatively (degree of abnormality, correlation coefficient 0.66, P = 0.005). The 22 patients with electrocardiographic evidence of anterior infarction had various degrees of abnormal regional motion and myocardial fibrosis. Discordance between wall motion and histologic findings was most common (50 percent of instances) in the 34 patients with anterior ST-T changes without infarction and generally was manifest as abnormal motion with normal histologic features. By contrast, normal motion and abnormal histologic features represented the most common type of discordance (22 percent of instances) in the 54 patients without either anterior infarction or ST-T deviation. These data provide a basis for inference of myocardial morphologic features (fibrosis) from assessment of ventriculographic wall motion and the electrocardiogram. They may thus be useful in predicting the potential functional benefits of bypass grafting of coronary arteries supplying abnormally contractile segments of the left ventricle.     

Percutaneous transvenous endomyocardial biopsy in human heart recipients. Experience with a new technique

Sixty-seven cardiac biopsy procedures have been performed in 17 cardiac transplant recipients at Stanford University Medical Center. Six other patients were biopsied as part of their assessment prior to transplantation. Biopsies were performed percutaneously through a sheath inserted into the right internal jugular vein. Two instruments were used, a Konno-Sakakibara bioptome and a new catheter biopsy forceps of our own design. Biopsies of the endomyocardium sufficient for examination by light and electron microscopy were obtained on all but one occasion. There were no deaths and no serious complications.Serial biopsies performed in the first two months after transplantation were used to diagnose and aid the management of acute rejection episodes. Biopsies on long-term survivors permitted the recognition of late acute rejection episodes and provided a new assessment of the myocardium following cardiac transplantation.Percutaneous transvenous endomyocardial biopsy is simple and safe to perform and is an important new aid in the management of patients following cardiac transplantation.     

Clinical experience with a porcine aortic valve xenograft for mitral valve replacement

Between March, 1971, and July, 1973, 103 patients underwent mitral valve replacement with a glutaraldehyde-preserved porcine aortic valve mounted on a flexible polypropylene, Dacron-covered stent. Overall operative survival was 95.1%. Actuarial analysis of late postoperative results indicates 92% survival through 2 years, with functional improvement in nearly all patients. The rate of systemic thromboembolism has been approximately 1.7% per patient-year without anticoagulants. No valve failure has occurred. We conclude that this xenograft prosthesis provides a technically and functionally satisfactory valve substitute, the durability of which appears to significantly exceed that of previously available tissue valves for mitral replacement.     

Quantitation of differences between spontaneous and induced liver tumors in mice with an automated image analyzer

Spontaneous hepatocellular neoplasms of B6C3F1 mice (basophilic neoplasms) as well as those induced with the herbicide Nitrofen (eosinophilic neoplasms) were observed with an image analyzing computer to determine if quantifiable morphologic differences existed between them. Several morphologic parameters were measured on 5 liver sections from each of the following groups: (a) unexposed control liver; (b) non-trabecular basophilic neoplasms; (c) trabecular basophilic neoplasms; (d) small well circumscribed eosinophilic neoplasms; and large irregular eosinophilic neoplasms without (e) and with (f) pulmonary metastases. The total number of hepatocytes per unit area was significantly smaller in the eosinophilic neoplasms than in the basophilic neoplasms or the controls. This was the result of a greatly increased cell cross-sectional area in the eosinophilic neoplasms, caused predominantly by a larger cytoplasmic cross-sectional area. Nuclear cytoplasmic ratios of cells in eosinophilic neoplasms were lower than in the other groups for this reason. This demonstrates that quantitative morphologic differences exist between the spontaneous and induced neoplasms, which supports the conclusion that Nitrofen is a true carcinogen, and not a promoting agent.