Changes in left ventricular inflow and pulmonary venous flow velocities during preload alteration in dilated heart

Challenges for 'diastology': contributions from Japanese researchers

Diastology is a study to treat diastole of the heart. Transmitral flow and pulmonary venous flow velocities recorded by pulsed Doppler echocardiography provide more important information about left ventricular (LV) diastolic dysfunction [left atrial (LA)-LV coupling] than cardiac catheterization in clinical practice; however, these waveforms are influenced by loading conditions, particularly preload. The early diastolic mitral annular and LV wall motion indices measured by tissue Doppler echocardiography can evaluate LV relaxation abnormality and filling pressure by being relatively preload independent. In addition, the role of concomitant systolic longitudinal dysfunction is well characterized in asymptomatic patients and in patients with heart failure and preserved ejection fraction. Two-dimensional speckle tracking echocardiography is an angle-independent method, and has the potential to evaluate the contraction and relaxation abnormalities in the longitudinal, circumferential, and radial directions of the LV myocardium as well as LV torsion/untwisting and, moreover, deformation of the LA myocardium and large arterial wall. As a result, this new technique can facilitate the early detection of impaired LA-LV-arterial coupling in patients before occurrence of overt heart failure symptoms.

Diastolic ventricular interaction in normal and dilated heart during head-up tilting

BACKGROUND

The normal human heart behaves as a single functional unit during preload reduction; adaptations of the left ventricle to head-up tilting is mediated through ventricular interdependence and biventricular-lung interaction.

HYPOTHESIS

We hypothesized that reduction of venous return in dilated cardiomyopathy is likely to have a great effect on ventricular chamber geometry and filling. The aim of this study was to evaluate the effects of gradual head-up tilting in normal subjects and in patients with dilated cardiomyopathy, addressing special attention to right (RV) and left ventricular (LV) dimensions, geometry, and filling, and to biventricular-lung interaction.

METHODS

Twenty normal subjects and 23 patients with moderate heart failure due to dilated cardiomyopathy were studied with two-dimensional and Doppler echocardiography in supine position and after 20 degrees, 40 degrees, and 60 degrees tilting. Right ventricular and LV dimensions, LV geometry, and tricuspid, mitral, and pulmonary venous flow patterns were recorded at each step of the study. Geometric changes of the LV were evaluated by measurements of volumes and diameters in the apical four-chamber view (which identifies the interventricular septum and lateral wall) and apical two-chamber view (which identifies the inferior and anterior wall of the LV).

RESULTS

In the two groups, tilting was associated with reduction of RV area and LV diameter and volumes; percent variations in LV diameter and volumes recorded in four-chamber view were lower at each step of tilting than with those derived from the two-chamber view in controls and in patients. In normal subjects, mitral and tricuspid peak early flow velocities were decreased at any tilting level; peak late velocities were unchanged; peak velocity of systolic forward flow of the pulmonary vein was reduced, diastolic forward flow was unchanged, and the difference in duration between reverse pulmonary flow and forward mitral A wave was reduced. Doppler findings were qualitatively similar in patients, but tilting induced a more marked redistribution of LV filling to late diastole because of a significant increase in atrial contribution.

CONCLUSIONS

Preload reduction by tilting induces profound effects on left and right dimensions, geometry, and filling in normal and dilated heart; reduction or RV dimensions are associated with changes in LV ventricular geometry (minimal reduction in septal-lateral diameter, marked reduction in anterior-posterior diameter), redistribution of right and left diastolic filling to late diastole, and redistribution of pulmonary venous flow to early diastole. These mechanisms are probably due to a favorable interaction between heart and lungs, which increases compliance within the pericardial space and facilitates redistribution of flow from the lungs. Even a minimal amount of preload reduction causes more marked effects in LV filling patterns in dilated cardiomyopathy than in normal hearts, confirming that ventricular interaction and pericardial constraint are increased when heart volume enlarges.

Effects of acute angiotensin-converting enzyme inhibition on diastolic ventricular interaction in the dilated heart

BACKGROUND

The normal and dilated heart behaves as a single functional unit during preload reduction: volume unloading in the setting of diastolic ventricular interaction allows for increased left ventricular (LV) filling.

HYPOTHESIS

We hypothesized that reduction of venous return induced by a physiologic stimulus (tilting) or by acute angiotensin-converting enzyme (ACE) inhibitors in dilated heart is likely to have a marked and similar effect on ventricular chamber geometry and filling. This study was designed to assess how the normal and dilated heart adapts to preload reduction.

METHODS

Twenty normal subjects and 20 patients with moderate heart failure due to dilated cardiomyopathy were studied with two-dimensional and Doppler echocardiography in supine position (B) and after 40 degrees of head-up tilting (T). The following day, patients repeated supine (C) and tilting test (TC) after administration of captopril (25 mg s.l.). Right ventricular (RV) and LV dimensions, LV geometry, and tricuspid, mitral, and pulmonary venous flow patterns were recorded at each step of the study.

RESULTS

In the two groups, T was associated with reduction of RV area and LV volumes; C and TC produced a similar effect on RV and LV. Changes in LV septal-lateral diameter and anterior-posterior diameter were different at each step of the study: during T (both groups) and after C and TC, the septallateral diameter increased slightly while the anterior-posterior diameter decreased. During T, mitral and tricuspid peak flow velocities decreased, peak late velocities were unchanged, and the deceleration time of mitral flow increased; the systolic forward flow of pulmonary venous flow decreased, the diastolic forward flow did not change, and the difference in duration between reverse pulmonary flow and mitral peak late flow decreased: C and CT induced similar changes.

CONCLUSION

Preload reduction induced by tilting or by ACE inhibitors induces profound and similar effects on LV and RV dimensions, LV geometry, and biventricular filling. Reduction of RV dimension is associated with adaptation of LV geometry and decrease of LV diastolic pressure, which facilitates LV filling and pulmonary venous drainage: ACE inhibition associated with tilting exerts an additional effect on these changes. These data confirm the role of ventricular interaction in modulating LV filling in heart failure.

Transesophageal Pulsed Doppler Echocardiographic Study of Systolic Flow Velocity Patterns of the Pulmonary Vein in Patients with Atrial Fibrillation

We recorded pulmonary venous flow velocity in 27 patients with atrial fibrillation using transesophageal pulsed Doppler echocardiography to investigate the cycle length-dependent characteristics and background of early systolic reversal and second systolic forward waves. The study group consisted of 15 patients with mitral stenosis, 5 patients with left atrial myxoma, and 7 patients without underlying organic heart disease; they were compared with 20 normal controls in sinus rhythm. The mean pulmonary capillary wedge pressure was significantly greater in patients with mitral stenosis and left atrial myxoma than in normal controls and in patients with isolated atrial fibrillation. The mean peak velocity of the early systolic reversal wave was also significantly greater in patients with mitral stenosis and left atrial myxoma than in patients with isolated atrial fibrillation. The mean peak velocity of the second systolic forward wave was significantly lower in patients with mitral stenosis and left atrial myxoma than in controls and in patients with isolated atrial fibrillation. The preceding RR interval had significant negative correlations with the peak early systolic reversal velocity, left atrial pressure during closure of the mitral valve, and peak V wave height of the pulmonary capillary wedge pressure in patients with mitral stenosis and left atrial myxoma. In the same patient groups, the preceding RR interval had significant positive correlations with the peak second systolic forward velocity and amplitudes of the mitral annular and interatrial septal motions during ventricular systole. The variations in the peak velocities of the early systolic reversal and second systolic forward waves with the preceding RR interval were smaller in patients with more severe mitral stenosis. In conclusion, early systolic reversal waves of the pulmonary venous flow velocity reflect left atrial pressure, and the second systolic forward waves reflect left atrial filling. Both velocities vary with disease conditions or preceding RR intervals in atrial fibrillation.

Utility of preload alteration in assessment of left ventricular filling pressure by Doppler echocardiography: a simultaneous catheterization and Doppler echocardiographic study

OBJECTIVES

The aim of this study was to demonstrate the usefulness of preload alterations in assessing left ventricular filling pressures with transmitral Doppler velocity curves.

BACKGROUND

Doppler mitral inflow velocities, used to estimate left ventricular filling pressures noninvasively, are limited in predicting left ventricular filling pressures, especially in patients with normal systolic function and a "pseudonormal" mitral filling pattern.

METHODS

Forty-nine patients were studied in the cardiac catheterization laboratory with simultaneous Doppler echocardiography using high fidelity catheters to compare left ventricular diastolic filling pressures (pre-A wave left ventricular pressure) and Doppler mitral inflow at baseline and during reduction of preload during the strain phase of the Valsalva maneuver (n = 27) or sublingual nitroglycerin (n = 36), or both (n = 14). Doppler measurements consisted of E (initial peak velocity), A (velocity at atrial contraction), deceleration time (time from E velocity to deceleration of flow extrapolated to baseline) and absolute A wave velocity (A' [peak A wave velocity minus velocity at onset of atrial contraction]).

RESULTS

In patients with high pre-A wave pressure (> or 15 mm Hg), there was a greater change in the E/A' ratio during the Valsalva maneuver than in patients with a normal pre-A wave pressure (-1.22 +/- 1.1 vs. -0.35 +/- 0.17; p = 0.02). A similar change was seen when comparing the change in the E/A' ratio after administration of nitroglycerin in patients with a high versus a normal pre-A wave pressure (0.81 +/- 0.49 vs. 0.18 +/- 0.17; p < 0.001). These differences were present in patients with a normal E/A ratio at baseline.

CONCLUSIONS

Alterations in preload during assessment of Doppler echocardiographic indexes may be useful in noninvasively assessing left ventricular filling pressures.