Ventricular Flow Dynamics With an Intra-Ventricular Balloon Pump: An In Vitro Analysis.

Due to the high treatment costs associated with durable ventricular assist devices, an intra-ventricular balloon pump (IVBP) was developed to provide low-cost, short-term support for patients suffering from severe heart failure. It is imperative that intraventricular flow dynamics are evaluated with an IVBP to ensure stagnation points, and potential regions for thrombus formation, are avoided. This study used particle image velocimetry to evaluate flow patterns within the left ventricle of a simulated severe heart failure patient with IVBP support to assess left ventricle pulsatility as an indicator of the likelihood of flow stasis. Two inflation timings were evaluated against the baseline severe heart failure condition: IVBP co-pulsation and IVBP counter-pulsation with respect to ventricular systole. IVBP co-pulsation was found to have a reduced velocity range compared to the severe heart failure condition (0.44 m/s compared to 0.54 m/s). IVBP co-pulsation demonstrated an increase in peak velocities (0.25 m/s directed toward the aortic valve during systole, as opposed to 0.2 m/s in severe heart failure), indicating constructive energy in systole and cardiac output (1.7 L/min increase with respect to severe heart failure baseline - 3.5 L/min) throughout the cardiac cycle. IVBP counter-pulsation, while exhibiting the greatest peak systolic velocity directed to the aortic valve (0.4 m/s) was found to counterasct the natural vortex flow pattern during ventricular filling, as well as inducing a secondary ventricular pulse during diastole and a 23% increase in left ventricle end-diastolic volume (indicative of dilation). Ideal IVBP actuation timing did not result in reduced intraventricular pulsatility, indicating promising blood washout.

Evaluation of an intraventricular balloon pump for short-term support of patients with heart failure.

The high cost of ventricular assist devices results in poor cost-effectiveness when used as a short-term bridging solution, thus a low-cost alternative is desirable. The present study aimed to develop an intraventricular balloon pump (IVBP) for short-term circulatory support, and to evaluate the effect of balloon actuation timing on the degree of cardiac support provided to a simulated in vitro severe heart failure (SHF) patient. A silicone IVBP was designed to avoid contact with internal left ventricular (LV) features (ie, papillary muscles, chordae, aortic, and mitral valves) based on LV computed tomography data of 10 SHF patients with dilated cardiomyopathy. The hemodynamic effects of varying balloon inflation and deflation timing parameters (inflation duty [D] and end-inflation point [σ]) were evaluated in a purpose-built systemic mock circulatory loop. Three IVBP actuation timing categories were defined: co-, transitional, and counterpulsation. Compared to the SHF baseline, co-pulsation increased aortic flow from 3.5 to 5.2 L/min, mean arterial pressure from 72.1 to 94.8 mmHg and ejection fraction from 14.4% to 21.5%, while mean left atrial pressure decreased from 14.6 to 10 mmHg. Transitional and counterpulsation resulted in a double ventricular pulse and extended the duration of increased ventricular pressure, potentially impeding diastolic filling and coronary perfusion. This in vitro study showed the IVBP could restore the hemodynamic balance of a simulated SHF patient with dilated cardiomyopathy to healthy levels.

Development of a cardiac loading device to monitor cardiac function during ex vivo graft perfusion.

BACKGROUND: Ex vivo heart perfusion systems, allowing continuous perfusion of the coronary vasculature, have recently been introduced to limit ischemic time of donor hearts prior to transplantation. Hearts are, however, perfused in an unloaded manner (via the aorta) and therefore, cardiac contractile function cannot be reliably evaluated. OBJECTIVES: We aim to develop a ventricular loading device that enables monitoring of myocardial function in an ex vivo perfusion system. In this initial study, was to develop a prototype for rat experimentation. METHODS: We designed a device consisting of a ventricular balloon and a reservoir balloon, connected through an electronic check valve, which opens and closes in coordination with changes in ventricular pressure. All balloons were produced in our laboratory and their properties, particularly pressure-volume relationships, were characterized. We developed a mock ventricle in vitro test system to evaluate the device, which was ultimately tested in ex vivo perfused rat hearts. RESULTS: Balloon production was consistent and balloon properties were maintained over time and with use on the device. Results from in vitro and ex vivo experiments show that the device functions appropriately; hemodynamic function can be measured and compares well to measurements made in an isolated, working (loaded) rat heart preparation. CONCLUSIONS: Our cardiac loading device appears to reliably allow measurement of several left ventricular hemodynamic parameters and provides the opportunity to control ventricular load.