Effect of postural changes, nitroglycerin and verapamil on diastolic ventricular function as determined by radionuclide angiography in normal subjects

Effects of changes in atrioventricular gradient and contractility on left ventricular filling in human diastolic cardiac dysfunction

The factors responsible for abnormalities in diastolic filling indexes as assessed by noninvasive testing in human beings have been extensively studied but are not completely understood. We therefore investigated left ventricular diastolic filling indexes by radionuclide angiography during right atrial pacing simultaneously with assessment of a directly measured left atrioventricular gradient and a time constant of isovolumic relaxation in 11 patients with hypertension and diastolic dysfunction. Loading conditions were altered with nitroprusside and phenylephrine, and contractility was improved by dobutamine infusion. The maximum left atrioventricular gradient at constant heart rates was determined by loading conditions and was not significantly affected by increases in contractility or an improvement in isovolumic relaxation rate. The peak filling rate according to radionuclide angiography was highly dependent on the atrioventricular gradient and was not affected by enhancement of the isovolumic relaxation rate.

Regional left ventricular wall thickness and systolic function during the first year after index anterior wall myocardial infarction: serial effects of ventricular remodeling

There is controversy regarding changes in regional left ventricular systolic function and thickness during remodeling after infarction. To address this, electron beam computed tomography was done in 22 patients with an index anterior wall infarction at discharge, 6 weeks, 6 months and 1 year, and global ventricular chamber volumes and mass quantified. A mid-ventricular short-axis scan from each study was divided into 4, 90 degrees sectors (anterior, septal, lateral and posterior walls). Regional wall thickness, ejection fraction, and absolute and percent wall thickening were determined and compared with 10 normal adults. Global infarct size was estimated at 24.2%+/- 3.4% of the ventricle. In these subjects, the ventricular chamber enlarged steadily during the year, while global ventricular mass initially decreased during the first 6 weeks, but then increased by 1 year. Regional ejection fraction changed little during the year, apart from the lateral wall, which was less than normal. Absolute wall thickening was reduced in the anterior (infarct) and septal walls throughout the year, but was normal and unchanged in the posterior and lateral walls. Regional percent wall thickening was not different from normal individuals. The anterior wall was thinned at discharge and tended to thin further during the year. The lateral wall was thinner than normal 6 weeks after infarction, but remained unchanged thereafter. The posterior wall tended to thin for the first 6 months, but the values at any time were not above normal. There was little change in septal wall thickness throughout the year. It is concluded that, after a moderate size, uncomplicated index anterior infarction, regional systolic function remains generally unaffected by remodeling. However, regional walls tend to thin and/or remain at normal thickness. These data confirm differential regional patterns after anterior infarction for systolic function, muscle atrophy and/or minimal hypertrophy which accompany serial changes in global ventricular chamber volumes and mass.

Serial changes in left and right ventricular systolic and diastolic dynamics during the first year after an index left ventricular Q wave myocardial infarction

OBJECTIVES

This study quantified serially biventricular emptying and filling after infarction and related these to changes in volume, muscle mass, wall stress and contractility.

BACKGROUND

There are limited data on serial changes in ventricular dynamics after infarction.

METHODS

Forty patients had serial electron beam computed tomographic examinations during the first year after index Q wave infarction (21 anterior, 19 inferior), and global biventricular volumes, peak rates of emptying and filling and left ventricular muscle masses were quantified. Mean mid-left ventricular end-systolic wall stresses, rate-corrected velocities of circumferential shortening and two indexes of left ventricular contractility--the end-systolic wall stress/volume ratio and the end-systolic wall stress/rate-corrected velocity of circumferential shortening relation--were estimated in each instance.

RESULTS

Patients with anterior infarction had an increase in biventricular chamber volume of 15% to 35% by 1 year. Global biventricular peak rates of emptying and filling were decreased by 20% to 30% from hospital discharge to 6 weeks but thereafter remained unchanged. Despite a significant increase in mean wall stresses, the end-systolic wall stress/volume ratio remained unchanged during the year. The rate-corrected velocities of circumferential shortening declined serially after anterior infarction but did so in proportion to the increase in mean wall stresses, consistent with no net change in left ventricular contractility. Patients with inferior infarction showed a trend toward similar changes, but the magnitudes did not reach significance.

CONCLUSIONS

Left (and right) ventricular global peak rates of emptying and filling during the first year after infarction can be altered in the absence of additional ischemic injury but are more consistent with responses to changes in left ventricular afterload than changes in intrinsic ventricular performance or contractility. Serial changes in left ventricular afterload after infarction are largely due to progressive chamber enlargement and limited development of compensatory hypertrophy during the first year. Intrinsic global left ventricular contractile performance was not altered by postinfarction cardiac remodeling in the patients examined.

Adjustment for the influence of age and heart rate on Doppler measurements of left ventricular filling

OBJECTIVE

To determine the normal range of pulsed Doppler measurements of left ventricular filling adjusted for age and heart rate.

DESIGN

Multiple regression was used to measure the effects of age and heart rate on pulsed Doppler indices of left ventricular filling in normal subjects. These regression equations were used to calculate a predicted normal value and 95% confidence interval (95% CI) for any subject from his age and heart rate.

PARTICIPANTS

61 subjects with no evidence of cardiovascular disease, aged 20 to 90 years, with a resting heart rate of 47-89 beats/min.

RESULTS

The effect of a 10 year increase in age was peak atrial filling velocity +15% (95% CI 12.0% to 18.5%); peak early filling velocity -3.2% (-6.0% to 0%); isovolumic relaxation time +6.2% (3.9% to 8.4%); acceleration time -3.8% (-6.0% to -1.5%); deceleration time +7.9% (5.1% to 10.8%). The effect of a 10 beat/min increase in heart rate was: peak atrial filling velocity +5.5% (1.2% to 10.1%); peak early filling velocity -4.0% (-8.1% to 2.0%); isovolumic relaxation time -2.5% (-4.6% to 0.6%); acceleration time -3.1% (-6.4% to 0.4%); deceleration time -1.8% (-4.0% to 3.8%).

CONCLUSION

For any individual, comparison of the predicted normal measurement and 95% CI with the observed measurement allows an assessment of the effects of disease on left ventricular filling that is independent of age and heart rate.

Ventricular performance before and after Fontan repair for univentricular atrioventricular connection: angiographic and radionuclide assessment

OBJECTIVES

This study was designed to evaluate changes in ventricular volume, mass and cardiac function before and after creation of an atrial to pulmonary connection in patients with a univentricular atrioventricular connection.

BACKGROUND

Intact systolic and diastolic performance is critical for successful establishment of an atrial dependent circulation, and few studies are available comparing cardiac performance before and after creation.

METHODS

With the use of radionuclide blood pool imaging and ventricular cineangiography, 54 patients (mean age 6.4 +/- 3.4 years) were studied. Twenty-eight patients were investigated preoperatively and 36 greater than 1 year after repair and compared with a control population.

RESULTS

Before operation, end-diastolic volume and wall mass were significantly increased compared with those of control subjects; however, the mass/volume ratio was normal (1.08 +/- 0.31 g/ml for the preoperative group; 0.97 +/- 0.19 for control subjects). Although end-diastolic volume returned to normal after the procedure, wall mass remained elevated and contributed to an elevated mass/volume ratio (1.20 +/- 0.38 g/ml). After the procedure, systemic vascular resistance index was significantly elevated compared with that before surgery or with that of control subjects (1,199 +/- 373, 2,120 +/- 645, 1,556 +/- 275 dynes.s.cm-5.m2: pre- and postrepair and control subjects, respectively). Radionuclide studies demonstrated that preoperative ejection fraction (52 +/- 9, 50 +/- 9, 60 +/- 8%), peak ejection (2.58 +/- 0.66, 2.95 +/- 0.81, 3.73 +/- 0.70 EDV/s) and peak filling rates (2.84 +/- 0.75, 2.75 +/- 0.79, 3.84 +/- 0.51 end-diastolic volumes [EDV/s]) were significantly reduced compared with those of control subjects and remained so after surgery.

CONCLUSIONS

These data suggest that systolic and diastolic function is depressed preoperatively in these patients, remains unchanged after the creation of an atrial-dependent circulation and is associated with an increased systemic vascular resistance. Long-term issues addressing preservation of cardiac function need to be prospectively studied.

Effect of postural changes and isometric exercise on Doppler-derived measurements of diastolic function in normal subjects

To determine if simple maneuvers that occur in daily life, such as changes in body position and isometric handgrip exercise, affect Doppler-derived measurements of diastolic function, we studied 22 normal male subjects in the supine position at rest and during several postural manipulations and during handgrip exercise. Comparison of values obtained in the 80 degrees upright tilt position with those obtained in the standard supine position revealed significant decreases in early diastolic flow velocity (peak E) (-25 +/- 3 percent; p less than 0.001), late diastolic flow velocity (peak A) (-9 +/- 3 percent; p less than 0.01), and the ratio of early to late flow velocities (E/A ratio) (-17 +/- 4 percent; significant increases in deceleration time (+55 +/- 10 percent; p less than 0.001) and isovolumic relaxation time (+38 +/- 4 percent; p less than 0.001). Comparison of values obtained with supine isometric exercise with those obtained during the preceding supine resting state revealed significant decreases in peak E (-12 +/- 3 percent; p less than 0.001) and the E/A ratio (-21 +/- 4 percent; p less than 0.001) and significant increases in peak A (+15 +/- 4 percent; p less than 0.001) and isovolumic relaxation time (+16 +/- 3 percent; p less than 0.001). The response of Doppler-derived measurements of diastolic function to postural changes and isometric exercise is complex and multifactorial. Interpretation of these measurements must take into account changes in loading conditions.

Evaluation of right ventricular early diastolic filling by cine nuclear magnetic resonance imaging in patients with hypertrophic cardiomyopathy

Numerous studies have established abnormalities in systolic and diastolic function of the left ventricle in hypertrophic cardiomyopathy. A consistent feature of this disease is reduced diastolic function of the left ventricle, but little information is available regarding right ventricular function in this disease. Cine nuclear magnetic resonance (NMR) imaging has been found to be effective for measuring right ventricular volumes and therefore was used to assess early diastolic filling of the right ventricle in patients with hypertrophic cardiomyopathy. Right ventricular time-volume curves were obtained from cine NMR images in 10 patients with hypertrophic cardiomyopathy and 8 normal subjects. Right ventricular volume was calculated with use of Simpson's algorithm at approximately 18 phases of the cardiac cycle and, from the curve, peak filling rate and filling fraction during the first third of diastole were determined. In patients with hypertrophic cardiomyopathy, peak filling rate tended to be less (176 +/- 46 vs. 305 +/- 50 ml/s, p less than 0.01) and filling fraction decreased (39.5 +/- 13.8 vs. 74.5 +/- 13.3%, p less than 0.01) in comparison with values in normal subjects. Thus, analysis of right ventricular time-volume curves obtained by using cine NMR imaging demonstrated diastolic dysfunction of the right ventricle in hypertrophic cardiomyopathy.

Effect of autonomic blockade, postural changes and isometric exercise on Doppler indexes of diastolic left ventricular function

Previous studies have demonstrated substantial changes in Doppler-derived indexes of left ventricular (LV) diastolic function in response to changes in loading conditions. To assess the influence of autonomic reflexes on these indexes, 2-dimensional and Doppler echophonocardiography were performed in 8 normal male subjects before and during autonomic blockade (0.2 mg/kg of propranolol and 0.04 mg/kg of atropine, intravenously) in the supine, passive upright 80 degree tilt and passive leg-raised positions, and during supine isometric exercise. During autonomic blockade in the supine position, there were significant increases in transmitral peak late filling velocity (A) (mean +/- standard error of the mean +34 +/- 7%) and isovolumic relaxation time (+18 +/- 9%), and significant decreases in transmitral peak early filling velocity (E) (-20 +/- 7%), deceleration time (-35 +/- 7%) and E/A ratio (-40 +/- 5%). E/A ratio decreased from 2.0 +/- 0.1 to 1.2 +/- 0.1 with autonomic blockade. When either upright tilt or isometric handgrip exercise was combined with autonomic blockade, the pattern of diastolic filling became distinctly "abnormal," with E/A ratio decreasing to 0.9 +/- 0.1. The effect of volume loading (increased end-diastolic volume and increased peak E) was seen in the legs-raised position only during autonomic blockade. It is concluded that autonomic blockade substantially alters the Doppler indexes of LV diastolic filling and modifies both hemodynamic response and Doppler indexes produced by positional changes and by isometric exercise.

Effects of acute alterations in left ventricular loading conditions on peak filling rate in the denervated (transplanted) ventricle

Peak filling rate is an indicator of left ventricular (LV) diastolic function. It is influenced by heart rate, loading conditions, sympathetic nervous system activity, ejection fraction and other factors. To determine the effect of altered loading conditions on peak filling rate, independent of heart rate and sympathetic nervous system activity, 12 patients were studied 3 weeks after orthotopic heart transplantation. Plasma catecholamine level, heart rate and ejection fraction were not changed by any maneuver. Nitroglycerin caused a decrease in pulmonary artery wedge pressure (9 +/- 2 to 6 +/- 1 mm Hg, p less than 0.001) and in absolute peak filling rate (46.0 +/- 3.0 to 42.8 +/- 2.5 kcts/s, p less than 0.01), but no change in normalized peak filling rate. Volume infusion increased pulmonary artery wedge pressure (9 +/- 2 to 12 +/- 2 mm Hg, p less than 0.001) and absolute peak filling rate (46.0 +/- 3.0 to 51.5 +/- 5.3 kcts/s, p less than 0.01), but peak filling rate normalized to stroke volume was unchanged. During nitroglycerin and volume infusions, there was a high correlation between changes in pulmonary artery wedge pressure and absolute peak filling rate (r = 0.82, p less than 0.001). With normalization of peak filling rate, these variables correlated less well. With methoxamine, 4 patients demonstrating systolic dysfunction had a decrease in absolute and normalized peak filling rate despite a large increase in pulmonary artery wedge pressure. The other 8 patients without systolic dysfunction had an increase in pulmonary artery wedge pressure with increased absolute but unchanged normalized peak filling rate.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study of left ventricular structure and function in elite athletes

Adaptations to left ventricular (LV) structure and function appear to be dependent on the type, intensity and duration of exercise training. We therefore studied two clearly defined groups of elite athletes, by M-mode and Doppler echocardiography, with a group of inactive individuals as controls. All groups were age matched. Group 1 comprised ten elite endurance athletes with maximal oxygen consumption (VO2 max) of 74.7 +/- 1.43 (mean +/- SEM). Group 2 consisted of ten elite weightlifters with VO2 max 45.3 +/- 2.00. Group 3 comprised of ten inactive individuals with VO2 max 44.5 +/- 2.13. Left ventricular end diastolic dimension was significantly higher in group 1 (5.72 +/- 0.07) than in groups 2 or 3 (5.29 +/- 0.09 and 5.19 +/- 0.09 respectively, p less than 0.001). Left ventricular mass index was significantly higher in groups 1 and 2 (156.4 +/- 5.97 and 138.6 +/- 7.27 respectively) than in group 3 (104.1 +/- 3.16 p less than 0.001). Percentage fractional shortening was used as an index of systolic function and no significant difference was found between groups. Doppler E:A ratio was taken as an index of diastolic function and was found to be significantly elevated in group 1 at rest (3.37 +/- 0.24) compared with 2.38 +/- 0.16 and 1.99 +/- 0.10 in groups 2 and 3 respectively (p less than 0.003). On exercise, the E:A ratio in group 1 was significantly higher than in group 3 (1.95 +/- 0.14 and 1.23 +/- 0.05 respectively p less than 0.001), and tended to be higher than group 2 (1.68 +/- 0.15 p = ns). These data show that both modes of intense training produce left ventricular hypertrophy. Diastolic function is not impaired in the athletes and may be augmented in the endurance athletes.

Effects of preload reduction on mitral flow velocity pattern in normal subjects

In the last few years, alterations in transmitral diastolic flow pattern have been used to assess changes in left ventricular diastolic properties. However, since diastolic flow primarily reflects the atrioventricular pressure gradient, loading conditions, as well as intrinsic left ventricular properties, should be able to affect this pattern. This study was selectively designed to decrease preload (a major determinant of the atrioventricular pressure gradient) in normal subjects to observe the effects on the Doppler transmitral flow pattern without pharmacologic interventions that may also affect left ventricular diastolic properties. In 12 normal subjects, preload was reduced by inflation of blood pressure cuffs placed at the level of the root of the 4 limbs. The peak velocity of early mitral flow (E wave) decreased from 62 +/- 8 to 51 +/- 7 cm/s (p less than 0.001), while no changes were found in the maximal velocity after atrial contraction; this caused a significant decrease in the ratio of these 2 velocities (the E to A ratio) from 1.5 +/- 0.3 to 1.1 +/- 0.1 (p less than 0.001). The time-velocity integral of early diastolic inflow decreased from 7.8 +/- 1.3 to 6.1 +/- 1.3 cm (p less than 0.001) with no significant changes of the time-velocity integral of inflow after atrial contraction. Therefore, preload reduction in normal subjects significantly reduces transmitral flow in early diastole with preserved late ventricular filling, producing a pattern that can mimic the changes previously described in left ventricular diastolic dysfunction.

Usefulness of verapamil for congestive heart failure associated with abnormal left ventricular diastolic filling and normal left ventricular systolic performance

Normal left ventricular systolic performance with impaired left ventricular diastolic filling may be present in a substantial number of patients with congestive heart failure (CHF). To evaluate the effect of oral verapamil in this subset, 20 men (mean age 68 +/- 5 years) with CHF, intact left ventricular function (ejection fraction greater than 45%) and abnormal diastolic filling (peak filling rate less than 2.5 end-diastolic volumes per second [edv/s]) were studied in a placebo-controlled, double-blind 5-week crossover trial. All patients underwent echocardiography to rule out significant valvular disease, and thallium-201 stress scintigraphy to exclude major active ischemia. Compared to baseline values, verapamil significantly improved exercise capacity by 33% (13.9 +/- 4.3 vs 10.7 +/- 3.4 minutes at baseline) and peak filling rate by 30% (2.29 +/- 0.54 vs 1.85 +/- 0.45 edv/s at baseline) (all p less than 0.05). Placebo values were 12.3 +/- 4.0 minutes and 2.16 +/- 0.48 edv/s, respectively (difference not significant for both). Improvement from baseline in an objective clinico-radiographic heart failure score (scale 0 to 13) was significantly greater with verapamil compared to placebo (median improvement in score: 3 vs 1, p less than 0.01). Mean ejection fraction and systolic blood pressure were unchanged from baseline; diastolic blood pressure and heart rate decreased to a small degree. Verapamil may have therapeutic efficacy in patients with CHF, preserved systolic function and impaired diastolic filling.

The effects of antihypertensive therapy on left ventricular mass in elderly patients

Left ventricular mass sometimes decreases during treatment of hypertension, but this response is inconsistent and its effects on left ventricular function are unknown. In a six-month randomized trial, we studied the ability of verapamil and atenolol to reduce left ventricular mass in 42 elderly patients with hypertension and the effects of this reduction in mass on cardiac function. The mean blood pressure (+/- SE) decreased in both the group that received verapamil (from 171.4 +/- 3.2/93.0 +/- 2.5 mm Hg to 142.9 +/- 2.8/79.0 +/- 2.0 mm Hg) and the group that received atenolol (from 179.6 +/- 4.6/98.5 +/- 2.4 mm Hg to 148.1 +/- 3.3/83.4 +/- 1.2 mm Hg), but the atenolol-treated patients more frequently required the addition of chlorthalidone to achieve blood-pressure reduction (P less than 0.01). Verapamil resulted in a reduction in the left-ventricular-mass index from 104 +/- 5 g per square meter of body-surface area to 85 +/- 5 g per square meter (P less than 0.01). Atenolol did not produce a reduction in the left-ventricular-mass index (109 +/- 9 g per square meter before treatment vs. 112 +/- 10 g per square meter after treatment). Two weeks after the withdrawal of antihypertensive therapy, blood pressure returned to pretreatment values. Nevertheless, in patients whose left ventricular mass had decreased, two measures of diastolic filling, the peak diastolic filling rate to the peak ejection rate, were significantly higher than before treatment (2.42 +/- 0.2 vs. 3.31 +/- 0.4 [P less than 0.05] and 0.61 +/- 0.03 to 0.85 +/- 0.05 [P less than 0.05], respectively). Diastolic filling was unchanged in the group that had no reduction in left ventricular mass. Cardiac output and the ejection fraction at rest and during mild exercise were unchanged in both groups as compared with baseline values. We conclude that left ventricular mass can be reduced in elderly patients with hypertension and mild ventricular hypertrophy who receive antihypertensive therapy. Reduction occurs more frequently with verapamil than with atenolol therapy, increases diastolic filling, and does not impair systolic function.

Influence of myocardial infarction size on radionuclide and Doppler echocardiographic measurements of diastolic function

To assess the relation between myocardial infarction size and diastolic function as measured by radionuclide ventriculography and Doppler echocardiography, 83 patients (aged 58 +/- 9 years) without significant valvular disease were studied 8 to 12 weeks after an acute myocardial infarction. Myocardial infarction size was measured by resting thallium-201 tomography. Peak early filling rate (in end-diastolic volumes/s) was measured by gated blood pool scintigraphy. Doppler measures of mitral inflow were peak early (E) and atrial (A) filling velocities, slopes of E and A, percent E and A filling, E/A ratio and diastolic filling period. In univariate analyses, there was a significant inverse correlation between infarction size and the peak early filling rate (r = -0.59, p less than 0.001), and this remained significant (r = -0.63, p less than 0.0001) in an analysis that included 2 other determinants of the filling rate, age and diastolic filling period. Infarction size was directly correlated to the peak E velocity (r = 0.37, p less than 0.01), deceleration of E (r = 0.41, p less than 0.01) and percent E filling (r = 0.31, p less than 0.01), and was inversely correlated to peak A (r = -0.27, p less than 0.05) and percent A filling (r = -0.26, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertension and left ventricular diastolic function

In recent years, there has been increased recognition of the relative importance of abnormalities of diastolic function in patients with essential hypertension. Indeed, diastolic dysfunction may be the earliest indicator of hypertensive heart disease. In this article, the mechanisms governing normal ventricular relaxation and the factors that may cause diastolic dysfunction are reviewed. Noninvasive clinical methods, particularly Doppler echocardiography and radionuclide angiography, for determination of diastolic function are outlined, and the limited experience in the management of hypertensive patients with abnormalities of diastolic function is discussed. When congestive heart failure develops in a patient with hypertension, it is especially important to determine whether it is due primarily to systolic or to diastolic left ventricular dysfunction.

Effect of the second-generation calcium channel blocking drug nisoldipine on diastolic left ventricular dysfunction in heart failure

The effect of intravenous nisoldipine (0.12 microgram/kg/min) on diastolic left ventricular (LV) dysfunction was studied from simultaneous hemodynamic and radionuclide measurements in 12 patients with New York Heart Association class II to IV cardiac failure. The initial LV filling fraction was low, the peak LV filling rate normalized for end-diastolic volume was decreased, and the pulmonary capillary wedge pressure (PCWP) was high and associated with clinical shortness of breath. Nisoldipine produced an increase in LV filling fraction from 36 +/- 17% to 43 +/- 20% (p = 0.003). The increase in filling took place in both early and late diastole: peak early filling rate (PFR) increased in 11 of the 12 patients (p = 0.02) and late diastolic filling rate (atrial [A] wave in eight of them (NS). When the determinants of these changes, were examined further, it was found that in the control state PFR was inversely related to LV end-systolic volume (r = 0.77), whereas the A wave was related in exponential fashion to PCWP (preload) (r = 0.79). Nisoldipine did not change the slope of these relationships, and it did not alter the end-diastolic pressure-volume relationship, implying that inherent myocardial relaxation and distensibility were unaltered by the drug. In summary, nisoldipine improved measurements of diastolic LV dysfunction in patients with cardiac failure. This study illustrates the importance of considering ventricular loading conditions when analyzing and interpreting measurements of diastolic ventricular dysfunction. The measured changes in diastolic LV function during infusion of nisoldipine appear to be due to alterations in ventricular loading conditions rather than to a direct myocardial effect of the drug.

Effects of a single dose of isosorbide-5-mononitrate on the left ventricular diastolic function in systemic hypertension

The effect of a single dose of isosorbide-5-mononitrate on left ventricular (LV) diastolic function was assessed by radionuclide ventriculography in 18 hypertensive patients. The effect of the mononitrate on atrial filling also was assessed. As expected, there was a significant decrease in mean blood pressure (120 +/- 17 to 102 +/- 18 mm Hg, p less than 0.005). Global LV ejection fraction did not show a significant change, increasing slightly from 64 +/- 9 to 68 +/- 8% (difference not significant). The mononitrate prolonged the time to peak filling rate from 176 +/- 36 to 195 +/- 29 ms (p less than 0.0001). The percentage of time to peak filling rate from diastole also increased, from 46 to 53% (p less than 0.05), whereas the normalized peak filling rate did not change (2.36 +/- 0.6 to 2.31 +/- 0.6 end-diastolic volumes/s, difference not significant). This effect on LV diastolic function was closely related to a certain reduction in preload, as suggested by the reduction in mean left atrial filling (45 +/- 12 to 40 +/- 13 counts/s, p less than 0.005) and LV diastolic counts, suggesting that the "impairment" of diastolic function induced by nitrates is secondary to the reduction in venous return to the left atrium. The mononitrate did not affect the mean right atrial filling rate (50 +/- 12 to 52 +/- 13 counts/s) and the right ventricular end-diastolic counts, suggesting a primary vasodilatory effect of nitrates on the pulmonary vascular bed.