Assessment of left ventricular diastolic suction in dogs using wave-intensity analysis

Abstract

. Assessment of left ventricular diastolic suction in dogs using wave-intensity analysis. Am J Physiol Heart Circ Physiol 288: H1641-H1651, 2005. First published November 24, 2004 doi:10.1152/ajpheart.00181.2004.-Two apparently different types of mechanisms have emerged to explain diastolic suction (DS), that property of the left ventricle (LV) that tends to cause it to refill itself during early diastole independent of any force from the left atrium (LA). By means of the first mechanism, DS depends on decreased elastance [e.g., the relaxation time constant ()] and, by the second, end-systolic volume (VLVES). We used waveintensity analysis (WIA) to measure the total energy transported by the backward expansion wave (IWϪ) during LV relaxation in an attempt to reconcile these mechanisms. In six anesthetized, open-chest dogs, we measured aortic, LV (PLV), LA (PLA), and pericardial pressures and LV volume by orthogonal ultrasonic crystals. Mitral velocity was measured by Doppler echocardiography, and aortic velocity was measured by an ultrasonic flow probe. Heart rate was controlled by pacing, VLVES by volume loading, and by isoproterenol or esmolol administration. IWϪ was found to be inversely related to and VLVES. Our measure of DS, the energy remaining after mitral valve opening, IWϪDS, was also found to be inversely related to and VLVES and was ϳ10% of the total "aspirating" energy generated by LV relaxation (i.e., I WϪ). The size of the Doppler (early filling) E wave depended on IWϪDS in addition to IWϩ, the energy associated with LA decompression. We conclude that the energy of the backward-going wave generated by the LV during relaxation depends on both the rate at which elastance decreases (i.e., ) and V LVES. WIA provides a new approach for assessing DS and reconciles those two previously proposed mechanisms. The E wave depends on DS in addition to LA decompression. diastole; hemodynamics; mitral valve; ventricles DIASTOLIC SUCTION (DS) is defined as that property of the left ventricle (LV) that tends to cause it to refill itself during early diastole independent of any force from the left atrium (LA). Two apparently different types of mechanistic explanations have emerged. The first type is represented by Katz (30) and Wiggers (52), who related DS to the decrease in ventricular elastance, and by several contemporary investigators (11,12,38,47) who emphasized the importance of the rate of LV relaxation in subsequent diastolic filling. In 1957, Wiggers wrote that "During early moments of ventricular relaxation, elastic stresses created during contraction are released. . . If blood could enter the ventricular chamber during this phase of diastole, such a rapid drop in pressure would unquestionably constitute a potent aspirating force" (52).Wiggers implied that the relaxing LV generates an "aspirating force" from the moment LV pressure begins to decrease. Accordingly, as elaborated upon below, the first effect of a relaxation-generated aspirating force must be to decelerate the mass represented by the stroke v...

Dynamic characterization and hemodynamic effects of pulmonary waves in fetal lambs using cardiac extrasystoles and beat-by-beat wave intensity analysis

“…4). As FEW ls is the vascular manifestation of a ventricular rarefaction ("suction") wave that accompanies ventricular relaxation (46), this finding is consistent with a reduction in the rate of ventricular relaxation in the first post-ES beat that has been reported in normal adult hearts (6,16).…”

“…As WI analysis utilizes pressure and velocity data, PT and left PA blood flows were converted to velocity (U) using crosssectional area derived from the nominal size of the flow probe (14,31,43,46). For steady-state WI analysis, an ensemble average of P and U signals was generated from a mean of 40 beats (range 28 -52).…”

“…For WI analysis, the rates of change of PT and left PA blood pressure (dP/dt) and velocity (dU/dt), and the product of these differentials (i.e., net WI), were calculated. Note that WI is a "time-corrected" variable that is independent of the digitizing sample rate (8,15,31,34,43), which contrasts with wave intensity defined by absolute changes in P and U between samples (i.e., dP ⅐ dU) used in a number of previous reports (12,14,18,22,30,46). However, the latter can be obtained from the time-corrected WI via division by the square of the sampling frequency (22).…”

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

“…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).…”

Left intraventricular diastolic and systolic pressure gradients

“…38 Temporal analysis conducted by Yotti et al 39 confirmed that in humans, suction is initiated during isovolumetric ventricular relaxation and continues during rapid filling. During early ventricular filling, suction causes pressure to fall despite filling.…”