End-systolic pressure-volume, pressure-length, and stress-strain relations in canine hearts

Abstract

End-systolic pressure-volume relationship (ESPVR) of the in situ heart in the dog was measured during changes in contractile state and was compared with end-systolic pressure-length (ESPLR) or stress-strain relationship (ESSSR). Circumferential segmental length and wall thickness at the equator and external long and short axis diameters of the left ventricle (LV) were determined sonomicrometrically, and LV volume was calculated by an ellipsoidal model. Circumferential wall stress at the equator was calculated by a very thin shell model. Contractile state was enhanced by an intravenous infusion of dobutamine and was suppressed by propranolol. ESPVR, ESPLR, and ESSSR were determined during a reduction of arterial pressure by occluding temporarily the inferior caval vein (IVC). ESPVR, ESPLR, and ESSSR during changes in end-systolic pressure from 108 +/- 3 to 71 +/- 2 mmHg were linear, irrespective of inotropic states (r greater than 0.92). Slopes of these relationships increased similarly in case of dobutamine and were reduced after propranolol, yet the extrapolated X-axis intercept of ESPVR, ESPLR, and ESSSR remained unchanged. Thus the slope of ESPVR is unique to the inotropic state, and both ESPLR and ESSSR are useful as a substitute for ESPVR when there is no regional wall motion abnormality.

Aortic wave intensity analysis of ventricular-vascular interaction during incremental dobutamine infusion in adult sheep

“…4). Second, the occurrence of FEW ms in the midportion of LV ejection, Ϸ140 and Ϸ75 ms before aortic valve closure at rest and at the highest dobutamine infusion rate, respectively, would place this wave in the midst of myocardial shortening (14) and the initial LV rotation related to contraction (9), and thus considerably before the onset of myocardial lengthening or LV untwisting. Third, one input in the calculation of aortic wave intensity, namely dU/dt, is directly related to the magnitude of blood inertial effects within the aorta (5).…”

“…Because dobutamine enhances LV contraction (8,14,30,35) and relaxation processes (15,33), and reduces vascular wave reflection (2), it might be expected that this agent would increase forward compression and expansion wave intensities but decrease backward compression wave intensity. However, the sole study of the actions of dobutamine using WIA, which was confined to an evaluation of total intensity at a single infusion rate, observed an increase in forward compression wave intensity but no change in the amplitude of other waves (13).…”

Measurement of end-systolic pressure-volume relations by intra-aortic balloon occlusion.

“…2,3,11,23,29 Although the volume intercept was found to be statistically inconsequential (Tables 2 and 3), we noticed a small but consistent increase in the intercept. Other investigators have reported similar findings.513 However, there may be gross errors inherent in extrapolating a value for the volume intercept, especially in light of recent findings that ESPVR may be curvilinear when evaluated throughout a larger left ventricular pressure range.15,16 Figure 4 shows the substantial deviations in the volume intercept when calculated from linear and nonlinear fits to data collected in typical physiologic ranges.…”

Numerical simulation for behind armor blunt trauma of human torso under non-penetrating ballistic impact

“…Consequently, the pressure wave propagates faster and has a wider range of influence. In contrast, the stress can only occur when the human organs is deformed by external force, so its propagation speed is slow and the incidence is small [36].…”