Altered myocardial force-frequency relation in human heart failure.

Abstract

Background. In congestive heart failure (idiopathic dilated cardiomyopathy), exercise is accompanied by a smaller-than-normal decrease in end-diastolic left ventricular volume, depressed peak rates of left

Effects of therapy using the Celacade system on structural and functional cardiac remodelling in rats following myocardial infarction

“…Loss of positive FFR has been reported in human and animal models of heart failure (1,22). The results of the present study showed that a positive FFR, measured at the stimulating frequency range of 0.5 Hz to 5 Hz and at the physiological temperature, was dramatically reduced in the rat heart with a large-area MI (ie, more than 30% of the LV surface; Table 1).…”

Determinants of frequency-dependent contraction and relaxation of mammalian myocardium

“…Second, and less well understood, is that the processes underlying frequency dependent behavior are geared to provide an increase in contractility, and thus may impact on the temporal resolution via which PRP is achieved. Further evidence in that PRP and FFR are closely linked is found in the studies on failing myocardium, where both PRP [53] and FFR [3,54] seem to be blunted and hallmarks of the contractile phenotype of failing myocardium.…”

Reversal of Atrial Mechanical Stunning After Cardioversion of Atrial Arrhythmias

“…8 In the failing heart, this inotropic effect of rate is either not found or is reversed. 8 Evidence implicates intracellular calcium homeostasis in frequency-dependent force generation, 9 in particular the sarcoplasmic storage and release of calcium.…”

“…In isolated cardiac muscle preparations, a positive force-frequency relationship has been described (inotropic effect of rate), whereas in failing ventricular myocardium, this relationship is reversed. 8 Frequency-dependent force generation appears to be mediated through intracellular calcium balance. 9 -10 Furthermore, with the use of isolated atrial myocardial fibers from patients with AF, Schotten and Allessie 11 have demonstrated a concentration-dependent increase in the force of contraction with isoproterenol or calcium and normalization of myocardial fiber contraction with calcium.…”