Energy transfer from systole to diastole: a novel device-based approach for the treatment of diastolic heart failure.

UNLABELLED: We hypothesized that attachment of elastic coil to the left ventricular (LV) wall, capable of exerting outward forces may allow the transfer of energy from systole to diastole and improve diastolic function. METHODS AND RESULTS: An extra-ventricular-device, composed of a series of elastic elements interposed between spiral screws attached to the epimyocardium of the LV free-wall was developed. The hemodynamic and mechanical effects of the device were tested using a computerized model, an in vitro model utilizing a computerized-controlled fluid pump, eight healthy sheep and 10 mini-pigs induced with diastolic dysfunction by renal wrapping. The computerized and in vitro models predicted a reduction of the LV diastolic pressure curve and partial normalization of the pressure-volume loop. The sheep study demonstrated preservation of animal's wellbeing including maintaining cardiac mechanical function with stable energy transfer from systole to diastole throughout the 6 months follow-up. The mini-pigs study showed an increase in the early diastolic to systolic strain-rate ratio in the mid-endocardial level (23 ± 10%, P = 0.008) and an increase in early apical reverse rotation rate of 50% (P = 0.016 compared to control). CONCLUSIONS: This study presents a novel concept of using a mechanical device to transfer energy from systole to diastole, potentially enhancing diastolic function.

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.

A two phase harmonic model for left ventricular function.

A minimal model for mechanical motion of the left ventricle is proposed. The model assumes the left ventricle to be a harmonic oscillator with two distinct phases, simulating the systolic and diastolic phases, at which both the amplitude and the elastic constant of the oscillator are different. Taking into account the pressure within the left ventricle, the model shows qualitative agreement with functional parameters of the left ventricle. The model allows for a natural explanation of heart failure with preserved systolic left ventricular function, also termed diastolic heart failure. Specifically, the rise in left ventricular filling pressures following increased left-ventricular wall stiffness is attributed to a mechanism aimed at preserving heart rate and cardiac output.

Future strategies for the treatment of diastolic heart failure.

It is estimated that 30% to 50% of heart failure patients have preserved systolic left ventricular (LV) function, often referred to as diastolic heart failure (DHF). Mortality is high in this patient population, and morbidity and rate of hospitalization are similar to those of patients with systolic heart failure. The management of patients with diastolic heart failure is essentially empirical, limited, and disappointing. New drugs, devices, and gene therapy based treatment options are currently under investigation. In this review, future strategies for the treatment of diastolic heart failure are discussed.