Reappraisal of the role of insulin in hypertriglyceridemia

We have previously proposed a sequential hypothesis to help explain the genesis of endogenous hypertriglyceridemia in man. This scheme states that insulin resistance → hyperinsulinemia → increased very low density lipoprotein (VLDL)-triglyceride (TG) production rate → increased plasma TG levels. In this study we have measured each of these metabolic variables in 34 nonobese subjects all consuming the same isocaloric diet. We have found highly significant positive correlations between insulin resistance and insulin response (r = 0.74, p < 0.0001), between insulin response and VLDL-TG production rate (r = 0.72, p < 0.0001), and between VLDL-TG production rate and plasma TG level (r = 0.88, p < 0.0001). Furthermore, these relationships were found to be independent of any possible effect of obesity. Thus, highly positive correlations were found for each step of the scheme, and we believe the over-all hypothesis is greatly strengthened. Additionally, the cross correlation between plasma TG levels and insulin response was also highly significant (r = 0.73, p < 0.0001). On the other hand, glucose response did not correlate with any measure of TG metabolism. On the basis of these results we conclude that insulin plays an important role in the genesis of endogenous hypertriglyceridemia through its influence on VLDL-TG production.     

Bacterial endocarditis with ruptured sinus of valsalva and aorticocardiac fistula

A case is presented of bacterial endocarditis with a ruptured sinus of Valsalva and formation of an aorticocardiac fistula from the right coronary sinus into the right atrium and right ventricle. The pathologic, clinical and surgical aspects of bacterial endocarditis complicated by a ruptured sinus of Valsalva and an aorticocardiac fistula are analyzed. This complication of bacterial endocarditis is still uncommon, but alertness to its diagnosis makes possible early and successful surgical treatment.     

Cor triatriatum: study of 20 cases.

Twenty cases of cor triatriatum are reported. The diagnosis was confirmed by necropsy in 16 cases and at the time of operation in 4. The lesion occurred as an isolated anomaly in 7 cases; in 13, other associated cardiac anomalies were present. Three anatomic types of cor triatriatum were identified in the cases studied at necropsy: diaphragmatic (10 cases), hourglass (3) and tubular (3). The diaphragmatic type was also present in all four cases in which the diagnosis was confirmed at operation. Associated anomalies were found in five cases of the diaphragmatic type and in each case of the hourglass of tubular types. In isolated cor triatriatum the clinical findings were characteristic of pulmonary venous and arterial hypertension. In two cases, one with a communication between the right atrium and the accessory left atrial chamber and one with partial anomalous pulmonary venous connection associated with cor triatriatum, the clinical findings suggested a large left to right shunt with pulmonary arterial hypertension. The clinical findings varied in the cases with associated anomalies, and it was difficult to determine the cause of disturbance of the circulation.     

Perioperative myocardial infarction related to coronary bypass surgery.

Frank lead electrocardiograms were recorded from 149 normal and abnormal adult males using four different electrode placements. All chest electrodes were placed at: (1) the fourth intercostal space level, (2) the fifth intercostal space level, (3) the fourth intercostal space level with V₄ substituted for C, and (4) the fifth intercostal space level with V₄ substituted for C.Differences in mean values of many commonly used amplitudes and orientations were not statistically significant among the four recording methods, but amplitude differences for individual subjects were often large and difficult to predict. When V₄ is substituted for C, as commonly done in some laboratories, R_x decreased and R_z increased by more than 10 per cent in about 40 per cent of the cases. In about 70 per cent of the cases, R_x and R_z changed significantly when electrode level was shifted from the fifth to the fourth intercostal space. For these 70 per cent, it does not appear possible to accurately predict increase or decrease of R_x, R_z, or QRS_m.Analysis programs which depend on individual amplitude measurements are likely to be significantly affected by electrode placement. It is suggested that criteria for analysis programs developed using a specified version of the Frank system should ideally be applied only to electrocardiograms recorded in the same manner.     

Long-term survival following aortic valve replacement.

Study was made of 95 survivors of aortic valve replacement during the early years of this procedure (1964 to 1970). The average follow-up time was 50.2 months. Survival was not related to hemodynamic parameters, such as cardiac index or left ventricular pressure, and did not appear to be influenced by the type of preoperative valve lesion. A history of angina pectoris and a New York Heart Association Class IV grouping were associated with shorter survival. Associated coronary artery disease was a leading cause of death in those patients surviving less than 2 years and angina pectoris the leading cause of morbidity in the long-term survivors. Sudden death occurred in five patients. Once a patient survived 36 months after the operation, the prognosis was excellent.     

Isometric effects on treadmill exercise response in healthy young men

This study evaluated the hypothesis that the isometric stress of load carrying augments the dynamic exercise response seen on the treadmill, and estimated the magnitude of this effect on heart rate and blood pressure for several methods of carrying the same load. Thirteen healthy subjects carried 40 lb in the right hand (H), 40 lb on the back (B), 20 lb in each hand (D) and no weight (N) while walking for 3 minutes on the treadmill at a grade of 0 at 1.7 miles/ hour. A statistically significant increase in the rate of rise and peak levels of systolic blood pressure, heart rate, estimated mean blood pressure, the product of estimated mean blood pressure and heart rate and systolic blood pressure-heart rate product was shown when task H was compared with tasks B, D and N. Values for tasks D and B did not differ significantly.The effects of isometric and dynamic exercise combined were greater than those of dynamic exercise alone. An effective technique of load distribution reduced the rate of increase in blood pressure, heart rate and the peak attained during dynamic exercise, thereby suggesting a lower level of myocardial oxygen consumption for a given weight-carrying task. These results can be applied to evaluation of patients with heart disease and estimation of their exercise tolerance.