Alterations in left ventricular diastolic function in conscious dogs with pacing-induced heart failure.

Abstract

We investigated in conscious dogs (a) the effects of heart failure induced by chronic rapid ventricular pacing on the sequence of development of left ventricular (LV) diastolic versus systolic dysfunction and (b) whether the changes were load dependent or secondary to alterations in structure. LV systolic and diastolic dysfunction were evident within 24 h after initiation of pacing and occurred in parallel over 3 wk. LV systolic function was reduced at 3 wk, i.e., peak LV dP/dt fell by -1,327±105 mmHg/s and ejection fraction by -22±2%. LV diastolic dysfunction also progressed over 3 wk of pacing, i.e., r increased by +14.0±2.8 ms and the myocardial stiffness constant by +6.5±1.4, whereas LV chamber stiffness did not change. These alterations were associated with increases in LV endsystolic (+28.6±5.7 g/cm2) and LV end-diastolic stresses (+40.4±53 g/cm2). When stresses and heart rate were matched at the same-levels in the control and failure states, the increases in r and myocardial stiffness were no longer observed, whereas LV systolic function remained depressed. There were no increases in connective tissue content in heart failure. Thus, pacing-induced heart failure in conscious dogs is characterized by major alterations in diastolic function which are reversible with normalization of increased loading condition. (J.

Chronic Infusion of Bradykinin Delays the Progression of Heart Failure and Preserves Vascular Endothelium-Mediated Vasodilation in Conscious Dogs

“…18 Thus, one mechanism by which BK exerts its protective effect on myocardial contractile function may be related to its effects on LV diastolic function. In agreement with previous reports, 15,16 this study showed a rightward shift of LV diastolic pressure-diameter curve, with an unchanged LV chamber stiffness after 3 weeks of pacing in vehicle-treated dogs. Chronic BK treatment reduced the rightward shift of the LV diastolic pressure-diameter relation but did not change LV chamber stiffness, which is in agreement with a recently developed concept.…”

“…As previously described, 3,14,15 in 16 beagle dogs weighing 13 to 21 kg anesthetized with 1 vol% halothane, a left thoracotomy was performed under sterile conditions for implantation of Tygon catheters in the descending aorta and left and right atria, a micromanometer in the left ventricular (LV) cavity, 2 pacing leads on the right ventricle, an ultrasonic flow probe around the root of aorta, and piezoelectric crystals in the LV to measure the internal short-axis and wall thickness in the same equatorial plane. The maintenance of animals, including postoperative care, analgesia, and antiinfectious prophylaxis, were kept in accordance with the Guide for the Care and Use of Laboratory Animals (NIH Publication No.…”

Canadian Cardiovascular Society consensus conference recommendations on heart failure 2006: Diagnosis and management

“…The presence of atrial fibrillation can potentially cause an adverse effect in several different ways (54)(55)(56)(57). Loss of atrial enhancement of ventricular filling may compromise cardiac output.…”

Efficacy of levosimendan in patients with chronic heart failure: Does rhythm matter?

“…Irregular contractions and rapid fastening heart beats cause decrease in left ventricular contractility and filling and impaired relaxation (19)(20)(21)(22). Intrinsic contractility of left atrium plays a major role in left ventricular diastolic filling (23).…”