Contribution of left ventricular diastolic function to exercise capacity in normal subjects.

Previous studies have established that most of the heterogeneity in exercise capacity seen with sedentariness, aging, or physical training can be accounted for by individual differences in the maximal rate of total body oxygen consumption (VO2 max) during dynamic exercise. However, the factors that limit VO2 max in normal subjects remain disputed. To test the hypothesis that differences in left ventricular diastolic performance contribute to the heterogeneity of VO2 max seen in healthy subjects, 57 normal sedentary volunteers (36 +/- 13 yr, range 20-76 yr) and 9 endurance athletes (37 +/- 8 yr, range 26-51 yr) were studied. Aerobic capacity was estimated as VO2 max during a multistage dynamic cycle exercise protocol, whereas resting left ventricular systolic and diastolic function was assessed by two-dimensional and Doppler echocardiography. The relationship of the left ventricular functional indexes with VO2 max was investigated by stepwise multiple regression analysis. VO2 max ranged from 25 to 58 ml.kg-1 x min-1 in sedentary subjects and from 44 to 60 ml.kg-1 x min-1 in athletes. With univariate analysis, significant correlations were observed between VO2 max and age (r = -0.60), maximal heart rate (r = 0.48), maximal work load (r = 0.80), left ventricular volumes at both end diastole (r = 0.51) and end systole (r = 0.62), peak early transmitral filling velocities (r = 0.80), and the ratio of early to late transmitral filling velocities (r = 0.87).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic and volume correlates of left ventricular diastolic relaxation and filling in patients with aortic stenosis.

OBJECTIVE: The aim of the present study was to evaluate the hemodynamic and volume correlates of early diastolic filling and isovolumetric relaxation in patients with aortic stenosis. BACKGROUND: Left ventricular diastolic relaxation and filling have been found to be heterogeneous in patients with aortic stenosis. Potential mechanisms underlying this heterogeneity include individual differences in the severity of muscle hypertrophy or systolic dysfunction, or both, in the presence and severity of mitral regurgitation and in the level of left atrial pressure. METHODS: Right (fluid-filled) and left (high fidelity micromanometer) ventricular pressures, left ventricular volumes (contrast angiography) and transmitral inflow dynamics (Doppler echocardiography) were measured in 17 patients with isolated severe aortic stenosis (valve area less than 0.75 cm2). Measurements included left ventricular end-diastolic and end-systolic volumes, left ventricular ejection fraction, peak positive and negative first derivative of left ventricular pressure (dP/dt), the time constant of isovolumetric relaxation (tau), left ventricular end-diastolic pressure, left ventricular mass, left ventricular end-systolic stress, mean capillary wedge pressure and peak early (E) and late (A) transmitral filling velocities. Patients were subclassified according to left ventricular ejection performance at rest and mean capillary wedge pressure. RESULTS: Patients with normal ejection performance and normal mean capillary wedge pressure had a normal rate of isovolumetric left ventricular pressure decay and an abnormal diastolic filling pattern, with diastolic filling occurring primarily during atrial systole. In contrast, in patients with systolic dysfunction and elevated mean capillary wedge pressure, isovolumetric pressure decay was prolonged and diastolic filling occurred essentially during the rapid filling period, with reduced atrial contribution to left ventricular filling and a short isovolumetric relaxation period. Stepwise multiple linear regression analysis identified two variables as independent predictors of transmitral velocity profile and three variables independently predictive of the rate of left ventricular pressure decay. The single most important predictor of transmitral filling pattern was the pulmonary capillary wedge pressure (p less than 0.0001), followed by the left ventricular peak negative dP/dt (p = 0.002). The single most powerful predictor of the rate of reduction in left ventricular pressure was left ventricular mass index (p less than 0.0001), followed by end-systolic volume index (p = 0.0002) and left ventricular peak negative dP/dt (p = 0.0029). CONCLUSIONS: In patients with aortic stenosis, left ventricular filling is essentially determined by left atrial pressure, whereas isovolumetric relaxation more closely depends on the severity of muscle hypertrophy and chamber dilation.

Prolonged exercise induces left ventricular dysfunction in healthy subjects.

To determine the effects of a moderately prolonged exercise on left ventricular systolic performance, 23 healthy male subjects, aged 18 to 51 yr (mean 37 yr) were studied. The subjects exercised first on a treadmill (brief exercise) and completed, on a separate day, a 20-km run. M-mode, two-dimensional, and Doppler echocardiography, as well as calibrated carotid pulse tracings, were obtained at rest and immediately on completion of both brief and prolonged exercise. Left ventricular systolic function was assessed by end-systolic stress-shortening relationships. Heart rate increased similarly after brief and prolonged exercise (+30%). Mean arterial pressure decreased from 99 +/- 7 to 92 +/- 8 mmHg (P less than 0.001) after prolonged exercise, but it remained unchanged after brief exercise. Left ventricular end-diastolic volume was decreased after prolonged exercise (130 +/- 23 vs. 147 +/- 18 ml at rest, P less than 0.01). Both ejection fraction and rate-adjusted mean velocity of fiber shortening decreased after prolonged exercise [from 67 +/- 5 to 60 +/- 6% (P less than 0.001) and from 1.12 +/- 0.2 to 0.91 +/- 0.2 cm/s (P less than 0.001), respectively] despite a lower circumferential end-systolic wall stress (133 +/- 23 vs. 152 +/- 20 g/cm2). The relationship between ejection fraction (or mean velocity of fiber shortening adjusted for heart rate) and end-systolic wall stress was displaced downward on race finish (P less than 0.05). These changes were independent of the changes in left ventricular end-diastolic volume and hence those in preload. The data suggest that moderately prolonged exercise may result in depressed left ventricular performance in healthy normal subjects.

Echocardiographic and color Doppler flow diagnosis of double-chambered right ventricle.

Double-chambered right ventricle is a rare condition in adults. This report of a 38-year-old asymptomatic woman details the importance of echocardiography, color flow imaging and continuous-wave Doppler for the noninvasive diagnosis of this entity.

Left ventricular filling in dilated cardiomyopathy: relation to functional class and hemodynamics.

Left ventricular systolic function does not correlate well with functional class in patients with dilated cardiomyopathy. To determine whether the correlation is better with Doppler indexes of left ventricular diastolic function, 34 patients with dilated cardiomyopathy (M-mode echocardiographic end-diastolic dimension greater than 60 mm, fractional shortening less than 25%, increased E point-septal separation) were studied. Patients were classified into two groups according to functional class. Group 1 consisted of 16 patients in New York Heart Association functional class I or II; group 2 included 18 patients in functional class III or IV. Left ventricular dimensions, fractional shortening, left ventricular mass, meridional end-systolic wall stress, peak early and late transmitral filling velocities and their ratio, isovolumetric relaxation period and time to peak filling rate were computed from pulsed wave Doppler and M-mode echocardiograms and calibrated carotid pulse tracings. Right heart catheterization was performed in 20 of 34 patients. No differences were observed between groups with regard to age, gender distribution, heart rate, blood pressure and M-mode echocardiographic-derived indexes of systolic function. Peak early filling velocity (72 +/- 13 versus 40 +/- 10 cm/s, p less than 0.001) was higher and atrial filling fraction (27 +/- 4% versus 46 +/- 8%, p less than 0.001) was lower in group 2 than in group 1. The ratio of early to late transmitral filling velocities was higher in group 2 patients (2.3 +/- 0.5 versus 0.7 +/- 0.2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of transmitral filling dynamics on continuous-wave Doppler assessment of aortic regurgitation by half-time methods.

The influence of transmitral filling dynamics on the evaluation of aortic regurgitation (AR) by continuous-wave Doppler pressure half-time was assessed in 30 consecutive patients in sinus rhythm with chronic moderate to severe AR. Pulsed-wave Doppler-derived regurgitant fraction (obtained from aortic and pulmonary stroke volumes) and color flow mapping relative regurgitant area (obtained from the parasternal short-axis view) were chosen as reference standards for the severity of AR. An excellent correlation was found between these 2 parameters (r = 0.98), while correlations were poor between pressure half-time and either regurgitant fraction (r = -0.74) or relative regurgitant jet area (r = -0.69). The ratio of early (E) to late (A) transmitral peak velocities was used to divide the study population into 2 groups: group A (n = 16) with E/A less than 1 and group B (n = 14) with E/A greater than 1. In patients with a similar degree of AR (estimated from Doppler regurgitant fraction or relative regurgitant jet area), the pressure half-time was found to be significantly shorter. Thus, the severity of AR in group A patients was overestimated (p less than 0.01). Compared to group B, group A patients were significantly shorter. Thus, the severity of AR in group A patients was overestimated (p less than 0.01). Compared to group B, group A patients were significantly older (p less than 0.02) and had a larger left ventricular mass (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)