The aim of the present study was to characterize intraventricular pressure gradients (IVPGs) in an animal model of chronic heart failure. New Zealand rabbits were treated with doxorubicin (heart failure group, n=5) or saline (control group, n=5) and instrumented with pressure catheters placed in the apex and outflow-tract of left ventricle (LV) and with sonomicrometer crystals placed in the apex and base of the LV free wall. In heart failure animals, ventricular filling was delayed and slower when compared with control animals. Moreover, the physiological nonuniformity observed between apical and basal segments in normal hearts was abolished in failing hearts. Simultaneously, physiological IVPGs observed during normal ventricular filling were entirely lost in heart failure animals. During ventricular emptying physiological nonuniformity between apical and basal segments observed in control animals was also abolished in heart failure animals. In failing hearts minimal length occurred later and almost at same time both in apical and in basal myocardial segments. Simultaneously, the characteristic IVPG pattern observed in healthy hearts during systole, which promotes ventricular emptying, was not observed in failing hearts. The present study showed that diastolic IVPGs, a marker of normal ventricular filling, and systolic IVPGs, a marker of normal ventricular emptying, are abolished in heart failure.

Department of Physiology and Cardiothoracic Surgery Cardiovascular R and D Unit Faculty of Medicine University of Porto Porto Portugal

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