Uncoupling between left ventricular contractility and relaxation after direct-current counter shocks

Large animal models for diastolic dysfunction and diastolic heart failure-a review of the literature

Diastolic heart failure (DHF) or heart failure with preserved systolic left ventricular function is estimated to account for approximately 40% of heart failure cases. Medical treatment of patients with DHF is limited and mainly empirical. Device-based therapy has an increasing role in the treatment of systolic heart failure and may have a future role in the treatment of DHF patients. Diastolic dysfunction and DHF are associated with anatomical and physiological characteristics, which need to be modeled in large animals in order to allow evaluation of device-based therapies, prior to clinical studies. In this article, we will review the large animal models for diastolic dysfunction and heart failure.

Thermodynamic phase plane analysis of ventricular contraction and relaxation

BACKGROUND

Ventricular function has conventionally been characterized using indexes of systolic (contractile) or diastolic (relaxation/stiffness) function. Systolic indexes include maximum elastance or equivalently the end-systolic pressure volume relation and left ventricular ejection fraction. Diastolic indexes include the time constant of isovolumic relaxation - and the end-diastolic pressure-volume relation. Conceptualization of ventricular contraction/relaxation coupling presents a challenge when mechanical events of the cardiac cycle are depicted in conventional pressure, P, or volume, V, terms. Additional conceptual difficulty arises when ventricular/vascular coupling is considered using P, V variables.

METHODS

We introduce the concept of thermodynamic phase-plane, TPP, defined by the PdV and VdP axes.

RESULTS

TPP allows all cardiac mechanical events and their coupling to the vasculature to be geometrically depicted and simultaneously analyzed.

CONCLUSION

Conventional systolic and diastolic function indexes are easily recovered and novel indexes of contraction-relaxation coupling are discernible.