Influence of the force-frequency relation on left ventricular function during exercise in conscious dogs.

Abstract

These findings indicate that force-frequency effects on the inotropic state of the intact LV are markedly enhanced by exercise.

Heart rate and force-frequency effects on diastolic function of the left ventricle in exercising dogs.

“…11,16,24 This method has been shown by others to be useful for demonstrating changes in early relaxation between interventions in the same animal.8 Tau also was calculated using a nonzero asymptote25 Use of this approach produced little change in the calculated values for tau (24±4.2 milliseconds at rest, 19.2±5.0 milliseconds during exercise after UL-FS 49, and 14.7±3.5 milliseconds during pacing, all differences significant, P<.01). Fig 1) E-5v1s -, ,-5VI3 * and the largest common maximum volume (50 mL on the paced heart rate curve, corresponding to end diastole, Fig 1).…”

“…The animals used in this investigation and the study protocol were different from those in our previous study on force-frequency effects during exercise. 16 …”

Levosimendan restores the positive force-frequency relation in heart failure

“…SW/PVA was improved (0.61 to 0.64). In conclusion, in HF, treatment with levosimendan restores the normal positive LV systolic and diastolic force-frequency relation and prevents tachycardia-induced adverse effect on LV-arterial coupling and mechanical efficiency.drugs; contractility; diastole; heart rate UNDER NORMAL CONDITIONS, an increase in heart rate (HR) augments myocardial contractility and the rate of relaxation (15,39,44). This force-frequency behavior is determined by both calcium handling and myofilament properties (26).…”

“…drugs; contractility; diastole; heart rate UNDER NORMAL CONDITIONS, an increase in heart rate (HR) augments myocardial contractility and the rate of relaxation (15,39,44). This force-frequency behavior is determined by both calcium handling and myofilament properties (26).…”

“…It has been shown that the integrated dynamic balance of the intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) is the primary cellular mechanism responsible for the force-frequency relation (FFR) and is determined by sarcoplasmic reticulum (SR) Ca 2ϩ load and Ca 2ϩ flux through the sarcolemma via L-type Ca 2ϩ channels and the Na ϩ -Ca 2ϩ exchanger (13). The positive FFR and relaxation-frequency relation (RFR) enhance cardiac performance during stress or exercise (7,36,39,44,52). In heart failure (HF), the positive FFR and RFR are impaired (16,24,28,29,44), and the abnormal left ventricular (LV)-arterial coupling is exacerbated by tachycardia.…”