Assessing Diastolic Function with Doppler Echocardiography Using a Novel Index: Ratio of the Transmitral Early Diastolic Velocity to Pulmonary Diastolic Velocity

Abstract

ABSTRACT. We developed a novel index to assess left ventricular (LV) relaxation as the ratio of transmitral early diastolic velocity to pulmonary diastolic velocity (E/D ratio). Mixed breed dogs (n=7) were anesthetized and their respiration was controlled. A 3.5-Fr micromanometer-tipped catheter was placed into the left ventricle. Dobutamine (5.0 or 10 µg/kg/min) or esmolol (100 or 500 µg/kg/min) was administered via the cephalic vein. The transmitral flow (TMF) and pulmonary venous flow (PVF) were recorded using transthoracic echocardiography from the apical long-axis view. The heart rate, systolic LV pressure, +dP/dt, and -dP/dt were significantly elevated by dobutamine, but significantly reduced by esmolol. Dobutamine significantly decreased τ, whereas esmolol significantly increased τ. The TMF-derived E and PVF-derived D wave velocities increased significantly with dobutamine, but decreased significantly with esmolol. A significant correlation was detected between the E and D wave velocities (r=0.92). Consequently, the E/D ratio was decreased significantly with dobutamine, and increased significantly with esmolol. Furthermore, the E/D ratio was significantly correlated with -dP/dt (r= -0.64) and τ (r=0.84). Our results suggest that the E/D ratio reflects LV relaxation, and may potentially provide further information on LV relaxation. KEY WORDS: diastolic function, E/D ratio, pulmonary venous flow, transmitral flow.J. Vet. Med. Sci. 70(4): 359-366, 2008 Evaluating the left ventricular (LV) diastolic function provides valuable information to assess the severity and prognosis of patients with heart failure [1,4,14,15,23]. Several methods are used for assessing LV diastolic function: catheterization-derived the peak positive (+dP/dt) and negative (-dP/dt) first derivatives of the left ventricular pressure and the time constant of isovolumic relaxation (τ), echocardiography-derived transmitral flow (TMF), pulmonary venous flow (PVF), and tissue Doppler imaging (TDI) [1,4,14,15,[23][24][25]34]. The main limitations in applying catheterization to clinical practice are its relatively high cost, take a lot of time, and invasive nature. In contrast, echocardiographic examination is non-invasive, repeatable, and reproducible [10,11]. The E/A ratio, which is obtained using the ratio of the early diastolic velocity (E wave) to the late diastolic velocity (A wave) derived from TMF, which indicate LV diastolic function [5,7,8,29,32]. However, it is well-known that TMF profiles are limited because of pseudonormalization.The PVF velocity profile is obtained using waveform relaxation during ventricular systole and early diastole, which indicates atrial function [20,24,25,31]. Several studies have reported that PVF profiles should provide additional information for predicting cardiac function and prognosis in patients with LV dysfunction [14,15,18,19,31]. The PVF patterns are closely related to LV diastolic function, left atrial pressure, and other cardiac dynamics [1,5,6,20,22]. However, the basic implication of PVF for ev...

Cardiac diseases in dogs

“…Rao et al (2008) used M-mode echocardiogram for measurement of echocardiographic indices and found it a useful technique in recognizing left ventricular dilation and poor contractile function in dogs with DCM. Evaluation of left ventricular diastolic function provide valuable information to determine severity and prognosis of cardiac disease (Hori et al, 2008). M-mode echocardiography is useful for early and confirmatory diagnosis and to quantify the left ventricular dysfunction in dogs with dilated cardiomyopathy (Sleeper et al, 2002;Rao et al, 2008).…”

Effects of various cardiovascular drugs on indices obtained with two-dimensional speckle tracking echocardiography of the left atrium and time–left atrial area curve analysis in healthy dogs

“…is a predominantly β 1 adrenergic receptor agonist with positive inotropic and lusitropic effects and is used for the treatment of dogs with cardiogenic shock or acute pulmonary edema caused by chronic mitral valve disease or dilated cardiomyopathy. 21 Esmolol is an ultra-short-acting, selective β 1 adrenergic receptor anagonist with negative inotropic and lusitropic effects 13,14,[24][25][26][27] and was selected because its effects were expected to contrast with those of dobutamine. Inodilators such as pimobendan are used to treat dogs with congestive heart failure, cardiogenic shock associated with mitral valve disease, or dilated cardiomyopathy.…”

“…[13][14][15] Milrinone g (25 µg/kg) was administered as a slow IV bolus for 5 minutes, followed by a CRI of 0.5 µg/kg/min. [13][14][15] Milrinone g (25 µg/kg) was administered as a slow IV bolus for 5 minutes, followed by a CRI of 0.5 µg/kg/min.…”

Echocardiography

“…141,144,180,188,189 Flow across the pulmonary venous ostia is driven by pressure gradients between the pulmonary venous system and the LA. 141,144,180,188,189 Flow across the pulmonary venous ostia is driven by pressure gradients between the pulmonary venous system and the LA.…”

“…119,176,182,185,187,190,297,298 Some relevant factors include active myocardial relaxation, ventricular fiber restoring forces (recoil), myocardial stiffness, chamber compliance, pericardial restraint, ventricular interaction, and LA contractility. 45,143,145,151,176,180,181,188,189,191,193,208,225,[302][303][304][305][306][307][308][309][310] The concepts are advanced, and the details are beyond the scope of this introductory chapter. The interplay among these factors is dynamic and complex.…”