Quantitative relationships between left ventricular ejection and wall thickening and geometry.

The quantitative relationships that exist between left ventricular (LV) wall shortening, wall thickening, and geometry during LV ejection are not well defined. We used a mathematical model to measure these parameters in 40 patients with various LV geometries studied by echocardiography. As opposed to wall shortening, the percent contribution of wall thickening to LV ejection (% delta Vh) was 25 +/- 2% in normal subjects; in all the patients, it varied from 18 to 45% and was inversely correlated (r = 0.

Validation and applications of indexed aortic prosthetic valve areas calculated by Doppler echocardiography.

Doppler echocardiographic evaluation of aortic valve prostheses is based on the use of variables heretofore validated mostly for native valves. Accordingly, this study examined the validity and relative usefulness of the Doppler valve gradient and area measurements in 31 patients (mean age 69 +/- 10 years) 20 +/- 4 months after implantation of a given type of aortic bioprosthesis ranging in size from 19 to 29 mm. Valve area data obtained with both the standard and simplified continuity equations were compared with known in vitro prosthetic valve area measurements and an excellent correlation was obtained between the standard and simplified continuity equations (r = 0.

Validation and applications of mitral prosthetic valvular areas calculated by Doppler echocardiography.

Doppler echocardiography is used in the noninvasive evaluation of mitral valve prostheses using parameters heretofore validated primarily for native valves. Accordingly, this study was designed to examine the validity and relative usefulness of valve gradient and area measurements in a group of 26 patients (17 women, 9 men, mean age 62 +/- 8 years), 19 +/- 4 months after implantation of different sizes (25 to 31 mm) of a given type of bioprosthesis. Areas obtained with both the continuity equation, using stroke volume measured in the left ventricular outflow tract, and the pressure half-time method are compared to known prosthetic areas derived from an in vitro hydraulic model.

Beneficial long-term effects of hydralazine in aortic regurgitation.

The long-term effects of vasodilators in asymptomatic patients with aortic regurgitation have not been studied extensively. We retrospectively reviewed the echocardiograms of 19 asymptomatic patients with significant aortic regurgitation followed up annually for up to 4 years (average +/- SD, 3.1 +/- 0.

Effect of ethane-I-hydroxy-I, I-diphosphonate on arterial calcinosis induced by hypervitaminosis D: a morphologic investigation.

The present study was undertaken to examine changes in vascular ultrastructure of rats subjected to hypervitaminosis D with or without treatment with ethane-I-hydroxy-I, I-diphosphonate (EHDP). Five groups of rats were studied. Untreated rats were given 0.

Prognosis in patients with a strongly positive exercise electrocardiogram.

In patients with a strongly positive exercise electro-cardiogram, the workload achieved during the test allows the identification of subsets with good or poor survival rates. To determine whether the same criteria also predict acute ischemic heart events such as unstable angina and myocardial infarction, fatal and nonfatal acute manifestations were documented in 241 patients medically treated during an 8-year follow-up. All patients had a Bruce protocol treadmill exercise test with ST-segment depression greater than or equal to 2 mm and coronary angiographic studies.

Effect of N-acetylcysteine on tissue necrosis during acute myocardial infarction in rabbits.

This study examined whether N-acetylcysteine, a low molecular weight compound used clinically to replenish glutathione, could limit tissue necrosis during acute myocardial infarction in hearts with minimal coronary collateral flow. Fifty rabbits underwent 45 mins ischemia with and without coronary reperfusion for 3h. Four groups were studied.

Effect of alprazolam on ischemia and reperfusion-induced ventricular arrhythmias in the isolated perfused rat heart.

The effects of the triazolobenzodiazepine anxiolytic, alprazolam, on the incidence of ischemia- and reperfusion-induced ventricular arrhythmias was studied in the isolated buffer-perfused rat heart. Administration of alprazolam before and after myocardial ischemia resulted in a dosage-dependent reduction in the incidence and duration of reperfusion-induced ventricular fibrillation and was significant at a concentration of 1 X 10(-3) mol/l alprazolam. This cardioprotective effect was not extended to ischemia-induced ventricular dysrhythmias.

Effects of perfluorochemical hemodilution on coronary blood flow distribution in dogs.

To determine the effect of perfluorocarbon (PFC) hemodilution on myocardial vessel capacity to autoregulate, circumflex coronary artery pressure-flow relations were studied in anesthetized dogs under three conditions: maximal vasodilatation before and after PFC; autoregulation before and after PFC with 100% oxygen supplemented with room air ventilation, and autoregulation with PFC hemodilution during either room air or 100% oxygen supplemented with room air ventilation. During coronary vasodilatation, PFC did not modify coronary conductance or zero-flow pressure. During autoregulation after PFC, the lower pressure limit of the autoregulatory pressure-flow relation was shifted leftward.

Endurance vs. strength training: comparison of cardiac structures using normal predicted values.

There are still disagreements concerning the adaptation of cardiac structures in relation to different training stimuli. To eliminate some of the variance due to individual differences in body surface area, we utilized a new approach based on the calculation of the percentages of each individual's normal predicted values (%NPV). We studied 46 strength (S, bodybuilders) and 57 endurance (E, runners) athletes.

A new and simple method to measure maximal aortic valve pressure gradients by Doppler echocardiography.

Most echocardiographic laboratories now use continuous-wave Doppler to measure transvalvular pressure gradients in patients with valvular aortic stenosis (AS). In many cases, particularly in the elderly, this technique can be difficult and time-consuming, and there is no immediate means of verifying the accuracy of the results. In the present study, a new and simple method is proposed to calculate maximal aortic valve gradients from the pulsed-wave Doppler tracing recorded in the left ventricular outflow tract.

Ultrastructural study of hypervitaminosis D induced arterial calcification in Wistar rats.

Hypervitaminosis D produces extensive vascular alterations which are similar to Monckeberg's calcinosis. The present study was undertaken to examine early changes in vascular ultrastructure of rats receiving tap water supplemented with either calcium chloride or a relatively low dosage of irradiated ergocalciferol ad libitum for 21 days. Untreated rats received normal tap water ad libitum.