Circulation Research, Vol 67, 352-359, Copyright © 1990 by American Heart Association

ARTICLES

Diastolic viscous properties of the intact canine left ventricle

SD Nikolic, K Tamura, T Tamura, M Dahm, RW Frater and EL Yellin
Department of Cardiothoracic Surgery, Albert Einstein College of Medicine, Bronx, NY 10461.

The viscoelastic model of the ventricle predicts that the rate of change of volume (strain rate) is a determinant of the instantaneous pressure in the ventricle during diastole. Because relaxation is not complete before the onset of filling, one cannot distinguish the individual effects of relaxation and viscosity unless the passive and active components that determine the ventricular pressure are separated. To overcome this problem, we used the method of ventricular volume clamping to compare the pressures in the fully relaxed ventricle at a given volume at zero strain rate (static pressure) and high strain rate (dynamic pressure). Six open-chest, fentanyl-anesthetized dogs were instrumented with micromanometers and an electronically controlled mitral valve occluder in series with the electromagnetic flow probe. We reasoned as follows: If there were significant viscosity, then the dynamic pressure would be higher than the static pressure. The static pressure was measured when the ventricle was completely relaxed following a mitral valve occlusion after an arbitrary filling volume had been achieved. The dynamic pressure was determined by delaying the onset of filling until relaxation was complete and then measuring the pressure at the same volume that was achieved when the static pressure was measured. In 19 different hemodynamic situations, the dynamic and static pressures were identical (mean difference, 0.1 +/- 0.8 mm Hg), indicating that in the passive ventricle viscoelastic effects are insignificant and do not contribute to the left ventricular diastolic pressure under normal filling rates.

This article has been cited by other articles:

				D.J.W. van Kraaij, P.E.J. van Pol, A.W. Ruiters, J.B.R.M. de Swart, D.J. Lips, N. Lencer, and P.A.F.M. Doevendans Diagnosing diastolic heart failure Eur J Heart Fail, August 1, 2002; 4(4): 419 - 430. [Abstract] [Full Text] [PDF]

				T. J. Fraites Jr, A. Saeki, and D. A. Kass Effect of Altering Filling Pattern on Diastolic Pressure-Volume Curve Circulation, December 16, 1997; 96(12): 4408 - 4414. [Abstract] [Full Text]

				S. P. Bell, J. Fabian, M. W. Watkins, and M. M. LeWinter Decrease in Forces Responsible for Diastolic Suction During Acute Coronary Occlusion Circulation, October 7, 1997; 96(7): 2348 - 2352. [Abstract] [Full Text]

				R. D. Berger, M. R. Wolff, J. H. Anderson, and D. A. Kass Role of Atrial Contraction in Diastolic Pressure Elevation Induced by Rapid Pacing of Hypertrophied Canine Ventricle Circ. Res., July 1, 1995; 77(1): 163 - 173. [Abstract] [Full Text]