Late Diastolic Flow Velocity Research Articles

Role of beta 2-adrenergic receptors on coronary resistance during exercise.

The effects of regional alpha- and specific beta 2-adrenergic receptor blockade on measurements of late diastolic coronary resistance (LDCR) and mean coronary blood flow velocity (CBFV) during exercise were examined in 14 conscious adult mongrel dogs. Specific beta 2-adrenergic receptor blockade (ICI 118.551) significantly decreased CBFV and increased LDCR by blockade of beta 2-vasodilator tone independent of alpha-adrenergic receptor-mediated tone and independent of altering myocardial metabolism. alpha-Adrenergic receptor blockade (phentolamine, 1 mg) significantly increased CBFV and decreased LDCR by blocking sympathetically mediated vasoconstrictor tone. There was no significant difference in the magnitude of response between alpha- and beta 2-adrenergic receptor blockade. These results demonstrate that alpha- and beta 2-adrenergic receptors have a significant and evidently equal influence on CBFV and LDCR during exercise. Four weeks of daily exercise and left stellate ganglionectomy (LSGx) prevented phentolamine-induced vasodilation but not ICI 118.551-induced vasoconstriction. This suggests that daily exercise and LSGx significantly decreased the alpha-adrenergic receptor-mediated vasoconstrictor tone on the coronary circulation, resulting in an apparently greater role for the coronary vascular beta 2-adrenergic receptor on the control of CBFV and LDCR during exercise.

Diastolic blood pressure as a determinant of Doppler left ventricular filling indexes in normotensive adolescents

Alterations in left ventricular filling can occur with aging and in patients with hypertension, ischemic heart disease, congestive and hypertrophic cardiomyopathy and congenital heart disease. This study examines the effects of blood pressure on left ventricular diastolic filling indexes measured by Doppler ultrasound technique in 47 young normotensive adolescents (mean age 13 years). Left ventricular filling was assessed by Doppler peak early and late diastolic transmitral flow velocities, early and late diastolic flow velocity integrals and early diastolic deceleration. Systolic blood pressure did not correlate with any of the Doppler filling indexes, although it was related to echocardiographic left ventricular mass (r = 0.44, p less than 0.005). Diastolic blood pressure did not correlate with left ventricular mass; however, it was inversely related to peak early diastolic flow velocity (r = -0.44, p less than 0.005), early diastolic flow velocity integral (r = -0.40, p less than 0.01) and early diastolic deceleration (r = -0.32, p less than 0.05). The ratio of late to early peak filling (A/E) was directly related to diastolic blood pressure (r = 0.48, p less than 0.001). Examination of electrocardiograms showed that there was a stronger correlation between A/E ratio and diastolic blood pressure (r = 0.63) in 22 subjects with bimodal P waves in lead V1 than in subjects with unimodal P waves (r = 0.45).(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment of left ventricular diastolic function by pulsed doppler echocardiography in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a primary myocardial disease in which symptoms may frequently result from impaired left ventricular relaxation, filling and compliance. In the present investigation, Doppler echocardiography was utilized to measure transmitral flow velocity and thereby assess left ventricular diastolic performance noninvasively in a group of 111 patients representative of the broad clinical spectrum of hypertrophic cardiomyopathy. In patients with hypertrophic cardiomyopathy, all Doppler indexes of diastolic relaxation and filling differed significantly (p less than 0.001) from those obtained in 86 control subjects without heart disease, namely, prolongation of isovolumic relaxation (94 +/- 24 versus 78 +/- 12 ms) and of the early diastolic peak of flow velocity (244 +/- 55 versus 220 +/- 28 ms), as well as slower deceleration (3.4 +/- 1.4 versus 4.9 +/- 1.3 m/s2) and reduced maximal flow velocity in early diastole (0.5 +/- 0.2 versus 0.6 +/- 0.1 m/s). As an apparent compensation for impaired relaxation and early diastolic filling, the atrial contribution to left ventricular filling was increased, as shown by increased late diastolic flow velocity (0.4 +/- 0.3 versus 0.3 +/- 0.1 m/s) and reduced ratio of maximal flow velocity in early diastole to that in late diastole (1.4 +/- 0.8 versus 2.1 +/- 0.9). The vast majority of patients with hypertrophic cardiomyopathy (91 [82%] of 111) showed evidence of impaired left ventricular diastolic performance, as assessed from the Doppler waveform. Abnormal Doppler diastolic indexes were identified with similar frequency in patients with (78%) or without (83%) left ventricular outflow obstruction, as well as in patients with (84%) or without (80%) cardiac symptoms. However, patients with nonobstructive hypertrophic cardiomyopathy showed more severe alterations in the Doppler indexes of diastolic function than did patients with obstruction. Thus, abnormal diastolic performance as assessed by Doppler echocardiography was apparent in the vast majority of the study patients with hypertrophic cardiomyopathy, independent of the presence or absence of cardiac symptoms or a subaortic pressure gradient. The high frequency with which diastolic abnormalities are identified in asymptomatic patients with hypertrophic cardiomyopathy suggests that impaired diastolic performance may be present at a time in the natural history of the disease when functional limitation is not yet evident.

Changes in intracardiac Doppler blood flow velocities in fetuses with absent umbilical artery diastolic flow

Umbilical artery Doppler blood flow velocity studies were used to identify 14 fetuses with absent flow during diastole to determine the significance of absent umbilical artery diastolic flow. Outcomes of these fetuses were recorded, and the associated intracardiac Doppler changes were identified in 12 of them. Maximal and mean intracardiac flow velocities were measured, and volume flows through the right (tricuspid valve, pulmonary valve) and left (mitral valve, aortic valve) sides of the heart were compared. Ratios of intracardiac peak flow velocity in late diastole to peak flow velocity in early diastole were calculated. Eleven fetuses had intrauterine growth retardation, and four had multiple congenital anomalies. Fetuses with no diastolic flow in the umbilical artery had increased volume flow across the tricuspid and pulmonary valves compared with normal fetuses of similar weights. The ratio of right-sided to left-sided volume flow in the heart (2.15:1) was increased compared with values in normal fetuses (1.33:1, p less than 0.01). The ratio of late diastolic to early diastolic peak flow velocities across the mitral valve was decreased (p less than 0.01). Absent umbilical artery diastolic flow is associated with increased tricuspid and pulmonary valve volume flow and changes in mitral flow velocity patterns, which suggests that there are alterations in left ventricular function.

Right ventricular filling detected by pulsed Doppler echocardiography during the convalescent stage of inferior wall acute myocardial infarction

To evaluate right ventricular (RV) diastolic function in patients with inferior wall acute myocardial infarction (AMI), flow velocity patterns of the RV inflow tract were studied in patients with anterior AMI (n = 32), inferior AMI (n = 32) and angina pectoris without left ventricular asynergy (n = 10) using pulsed Doppler echocardiography. Doppler examinations were performed at least 4 weeks after the attack. Twenty-seven healthy persons served as control subjects. Three Doppler variables were measured at the RV inflow tract: the ratio of the late diastolic peak flow velocity due to atrial contraction to the rapid filling peak flow velocity in early diastole ( sol A E ) and the acceleration time and deceleration time of the RV rapid filling wave. sol A E in patients with inferior AMI (1.01 ± 0.24, mean ± standard deviation) was significantly greater than in those with anterior AMI (0.80 ± 0.16, p < 0.001) and angina pectoris (0.79 ± 0.17, p < 0.01) and in normal subjects (0.70 ± 0.17, p < 0.001). sol A E in patients with inferior AMI correlated with the ratio of left ventricular to RV end-diastolic pressure (r = −0.60, p < 0.05). sol A E in inferior AMI with relatively high RV end-diastolic pressure (more than 8 mm Hg, n = 8) was significantly greater than that in those with normal pressure (8 mm Hg or less, n = 9). sol A E in patients with proximal right coronary artery occlusion was significantly greater than that in those with distal occlusion. Deceleration time/√RR in patients with inferior AMI (4.5 ± 1.1) was significantly longer than that in patients with anterior AMI (3.6 ± 1.1, p < 0.01), angina pectoris (3.7 ± 0.5, p < 0.01) and in control subjects (3.5 ± 0.5, p < 0.001). These data indicate that early to mid-RV diastolic filling is impaired in inferior AMI and that pulsed Doppler echocardiography is useful for detecting the RV hemodynamic abnormality of RV filling.

Doppler echocardiographic assessment of left ventricular systolic and diastolic function in mild hypertension.

Abnormalities in left ventricular (LV) wall thickness and mass have been demonstrated in patients with mild hypertension utilizing M-mode echocardiography. In addition, studies using radionuclide angiography have demonstrated abnormalities in early diastolic LV filling in asymptomatic hypertensive patients with normal ejection fraction and cardiac output. Recently, Doppler recordings of flow velocity in the ascending aorta and through the mitral valve have been shown to provide useful information about LV function. To determine whether flow abnormalities could be detected in patients with mild hypertension, we recorded Doppler aortic and mitral valve flow velocities in 21 men with mild hypertension. Casual systolic blood pressure was 147 +/- 18 mm Hg (mean +/- SD) and diastolic blood pressure was 96 +/- 9 mm Hg. LV mass (310 +/- 75 g) was elevated (i.e., above the 95% normal prediction interval) in 8 of 19 patients who underwent M-mode echocardiography; LV ejection fraction was normal in all patients (mean, 80%). As in previous studies in normal subjects, we found in these hypertensive patients an inverse correlation between age and both aortic peak flow velocity (r = -0.51, p less than 0.05) and transmitral early diastolic peak flow velocity (r = -0.44, p less than 0.05) and a positive relationship between age and mitral valve late diastolic peak flow velocity (r = 0.73, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of imaging view and sample volume location on evaluation of mitral flow velocity by pulsed Doppler echocardiography

Pulsed Doppler mitral flow velocity measurements have been used to evaluate left ventricular diastolic filling. In normal persons these measurements are affected by age and respiration, but not by gender, body surface area or normal blood pressure. Additional factors that may influence these measurements include the imaging view and sample volume location. In this study, the effects of imaging view and sample volume location were evaluated in 52 normal subjects, aged 21 to 78 years. Pulsed Doppler recordings were obtained from the apical 4-chamber and apical 2-chamber views with the sample volume located both in the left atrium and at the level of the mitral valve leaflet tips. Doppler measurements were slightly, but not significantly, higher (4% on average) for recordings obtained from the apical 4-chamber than from the 2-chamber view for peak flow velocity in both early and late diastole. However, apical 4-chamber recordings from a sample volume in the left atrium resulted in measurements significantly lower (p < 0.05) for both early and late diastolic mitral peak flow velocity than those obtained near the mitral leaflet tips (peak flow velocity in early diastole = 43 ± 12 vs 57 ± 12 cm/s and peak flow velocity in late diastole = 36 ± 7 vs 46 db 11 cm/s, respectively). The higher mitral peak flow velocity values recorded in early and late diastole near the mitral leaflet tips may be related to the smaller flow area at the mitral valve orifice compared with the left atrium. Neither imaging view nor sample volume location resulted in significant differences in the ratio of late-to-early diastolic peak flow velocity. Pulsed Doppler mitral flow velocity measurements must be standardized for sample volume location when evaluating ventricular diastolic filling.

Left ventricular filling in hypertrophic cardiomyopathy: A pulsed Doppler echocardiographic study

Abnormal left ventricular diastolic properties have been described in patients with hypertrophic cardiomyopathy. To evaluate the diastolic filling characteristics of the left ventricle in patients with this disease, pulsed Doppler echocardiography was used to study mitral flow velocity in 17 patients with hypertrophic cardiomyopathy (11 with and 6 without systolic anterior motion of the mitral valve) and 16 age-matched normal subjects. There were no statistically significant differences between patients with hypertrophic cardiomyopathy with and without systolic anterior motion with regard to ventricular septal thickness, left ventricular posterior wall thickness, left ventricular internal dimensions or the extent of hypertrophy evaluated by two-dimensional echocardiography. Mitral regurgitation was detected by Doppler echocardiography in all 11 patients with and in 2 (33%) of the 6 patients without systolic anterior motion of the mitral valve. Early and late diastolic peak flow velocity, the ratio of late to early diastolic peak flow velocity and deceleration of early diastolic flow were measured from Doppler mitral flow velocity recordings. There were no statistically significant differences in these four indexes between the patients with systolic anterior motion and normal subjects. In contrast, the patients with hypertrophic cardiomyopathy without systolic anterior motion showed lower early diastolic peak flow velocity, higher ratio of late to early diastolic peak flow velocity and lower deceleration of early diastolic flow compared with the patients with systolic anterior motion and normal subjects, suggesting impaired left ventricular diastolic filling.(ABSTRACT TRUNCATED AT 250 WORDS)