Weaning of rotary blood pump recipients after myocardial recovery: a computer study of changes in cardiac energetics

Schima, Heinrich; Vollkron, Michael; Boehm, Herbert; Röthy, W.; Haisjackl, Markus; Wieselthaler, Georg; Wolner, Ernst

doi:10.1016/j.jtcvs.2003.09.029

Cited by 21 publications

(12 citation statements)

References 24 publications

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“…In the modern era of continuous flow ventricular assist devices (cfVADs), such models have been used to identify algorithms for feedback control so as to adequately unload the native ventricle [1]–[4], avoid suction [5], and potentially promote cardiac recovery [6], [7]. Surprisingly, only a few of these simulations [2] have employed models of the diseased heart that reflect cardiac overload (myocardial overstretch)—one of the most common characteristics of end stage heart failure.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Dilated Heart Failure with Continuous Flow Circulatory Support

et al. 2014

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Lumped parameter models have been employed for decades to simulate important hemodynamic couplings between a left ventricular assist device (LVAD) and the native circulation. However, these studies seldom consider the pathological descending limb of the Frank-Starling response of the overloaded ventricle. This study introduces a dilated heart failure model featuring a unimodal end systolic pressure-volume relationship (ESPVR) to address this critical shortcoming. The resulting hemodynamic response to mechanical circulatory support are illustrated through numerical simulations of a rotodynamic, continuous flow ventricular assist device (cfVAD) coupled to systemic and pulmonary circulations with baroreflex control. The model further incorporated septal interaction to capture the influence of left ventricular (LV) unloading on right ventricular function. Four heart failure conditions were simulated (LV and bi-ventricular failure with/without pulmonary hypertension) in addition to normal baseline. Several metrics of LV function, including cardiac output and stroke work, exhibited a unimodal response whereby initial unloading improved function, and further unloading depleted preload reserve thereby reducing ventricular output. The concept of extremal loading was introduced to reflect the loading condition in which the intrinsic LV stroke work is maximized. Simulation of bi-ventricular failure with pulmonary hypertension revealed inadequacy of LV support alone. These simulations motivate the implementation of an extremum tracking feedback controller to potentially optimize ventricular recovery.

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Section: Introductionmentioning

confidence: 99%

Simulation of Dilated Heart Failure with Continuous Flow Circulatory Support

et al. 2014

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“…They are well-suited as an interim therapy for left-ventricular insufficiency, as well as an end-stage treatment for patients who cannot undergo transplantation for a variety of reasons (3,4). Over the last few years, these systems have emerged as a feasible alternative to conventional pulsatile pumps, although several questions concerning physiology are still being addressed in a number of studies (5-9), including computer models (10). Aspects of the hemodynamic basis of ventricular assist devices (VADs) have been discussed particularly with respect to arterial blood flow pulsatility and histologic changes.…”

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confidence: 99%

Coronary Hemodynamics and Myocardial Oxygen Consumption During Support With Rotary Blood Pumps

et al. 2009

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Mechanical support offered by rotary pumps is increasingly used to assist the failing heart, although several questions concerning physiology remain. In this study, we sought to evaluate the effect of left-ventricular assist device (VAD) therapy on coronary hemodynamics, myocardial oxygen consumption, and pulmonary blood flow in sheep. We performed an acute experiment in 10 sheep to obtain invasively measured coronary perfusion data, as well as pressure and flow conditions under cardiovascular assistance. A DeBakey VAD (MicroMed Cardiovascular, Inc., Houston, TX, USA) was implanted, and systemic and coronary hemodynamic measurements were performed at defined baseline conditions and at five levels of assistance. Data were measured when the pump was clamped, as well as under minimum, maximum, and moderate levels of assistance, and in a pump-off condition where backflow occurs. Coronary flow at the different levels of support showed no significant impact of pump activity. The change from baseline ranged from -10.8% to +4.6% (not significant [n.s.]). In the pulmonary artery, we observed a consistent increase in flow up to +4.5% (n.s.) and a decrease in the pulmonary artery pressure down to -14.4% (P = 0.004). Myocardial oxygen consumption fell with increasing pump support down to -34.6% (P = 0.008). Left-ventricular pressure fell about 52.2% (P = 0.016) as support was increased. These results show that blood flow in the coronary arteries is not affected by flow changes imposed by rotary blood pumps. An undiminished coronary perfusion at falling oxygen consumption might contribute to cardiac recovery.

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“…A recent metaanalysis of seven studies claimed a higher freedom from recurrence of heart failure in patients weaned from continuous support compared with pulsatile pumps [18 & ]. This finding may yet not be due to the different degrees of pulsatility, but influenced by better ventricle evaluation and training conditions of rotary pumps in low support compared with membrane pumps [19,20]. For such myocardial evaluation and potential training, the timing of pulsatility may be crucial.…”

Section: Heart and Ventricular Recoverymentioning

confidence: 99%