Assessment of right ventricular diastolic suction in dogs with the use of wave intensity analysis

Abstract

-Diastolic suction (DS) can be defined as that property of the ventricle by means of which it tends to refill itself during early diastole, independent of any force from the atrium. Although thought to be significant in the left ventricle (LV), DS in the right ventricle (RV) has received little attention, probably because of RV geometry. Our recent LV studies have shown that DS is related to both decreased elastance (i.e., , the relaxation time constant) and end-systolic volume (V LVES), thus reconciling the two mechanisms that have been used to explain the concept of DS. We hypothesized that RV DS would similarly depend on and V RVES. In six anesthetized open-chest dogs, aortic, RV, right atrial (RA), pulmonary arterial (PA), and RV pericardial pressure, tricuspid velocity, and PA flow were measured. VRVES was calculated by measuring distances between eight ultrasonic crystals. An empirical index of relaxation, Ј, and VRVES were manipulated by volume loading/caval constriction and isoproterenol/esmolol. We calculated the total energy (IWϪ) of the backward expansion wave generated during RV relaxation and that component causing DS [IWϪ(DS)]; i.e., the energy remaining after tricuspid valve opening. IWϪ [IWϪ(DS) also] was found to be inversely related to Ј and to VRVES {i.e., IWϪ ϭ Ϫ8.85 ⅐ e (Ϫ0.0423Ј) ⅐ e [Ϫ0.0665(%VRVES)] }. Thus, as for the LV, the energy of the backward-going wave generated by the RV during relaxation depends on both the rate at which elastance decreases and the completeness of ejection. Despite the thin wall and nonspherical shape of the RV, DS appears to be an important mechanism. diastole; hemodynamics; tricuspid valve; velocity; pressure THE UNIQUE CAPABILITIES of wave intensity analysis (WIA) could provide information regarding the dynamics and mechanisms of early right ventricular (RV) filling. Conceptually, diastolic suction (DS) is that property of the ventricle by which it tends to refill itself during early diastole, independent of any force from the atrium. Two apparently different types of mechanistic explanations have emerged. One is decreasing elastance; the other is the degree to which the ventricle empties (i.e., endsystolic volume) (11,12,19,22,38,42). Sabbah and colleagues (31, 32) indicated that RV early diastolic pressure is negative in both humans and dogs (perhaps reflecting RV DS) and that the RV can create a sucking effect during early diastole that may contribute to the filling process. Recently, our group clarified the mechanisms of left ventricular (LV) DS using WIA (41).The purpose of this study was to measure the energy associated with RV relaxation (I WϪ , see below) and to test the hypothesis that I WϪ depends on both the rate at which elastance decreases (Ј, an index of the exponential time constant of RV relaxation) and the completeness of RV emptying [RV end-systolic volume (V RVES )]. In particular, the energy associated with RV DS was identified as that component of I WϪ that remains after the opening of the tricuspid valve [I WϪ(DS) ]. METHODSExperimental ...

Wave intensity analysis of left atrial mechanics and energetics in anesthetized dogs

“…As discussed in previous studies (29,42,44), there are limitations in applying one-dimensional WIA to the complex three-dimensional geometry of the LV. However, we assume that the quasi-cylindrical mitral orifice can be considered to be a one-dimensional system, regardless of the possible complexity of wave motion in the LV cavity.…”

Do we have two hearts? New insights in right ventricular function supported by myocardial imaging echocardiography

“…Nevertheless, the development of indexes for RV function has evolved slowly, and numerous gaps remain in our understanding of RV diastolic function. New model parameters and related diastolic properties that allow accurate quantitative assessment of RV diastolic function abnormalities in animal models have been described [59].…”

Noninvasive Assessment of the Right Ventricular Filling Pressure Gradient

“…However, several studies have established a role of early diastolic suction as a determinant of RV filling during early diastole. 22,23,27 During this phase, the RV also is capable of lowering intracavitary pressure below RA values and continuing to decrease its pressure despite its increasing volume. The finding of our study of a peak RVFPD lower than the peak left-side equivalent (typically in the 3.5-to 4-mm Hg range) is probably explained by the slower relaxation rate of the RV compared with the LV.…”