Continuous assessment of cardiac function during rotary blood pump support: A contractility index derived from pump flow
ABSTRACT The clinical application of rotary blood pumps (RBPs) for bridge-to-recovery and destination therapy has focused interest on the remaining contractile function of the heart and its course. This study reports a method to determine contractility that uses readily measured variables of the RBP.
The proposed index (I(Q)) is defined as the slope of a linear regression between the maximum derivative of the pump flow and its peak-to-peak value. I(Q) was compared with the maximal derivative of ventricular pressure (dP/dt(max)) vs end-diastolic volume (EDV) and the pre-load-recruitable stroke work. All indices were evaluated using computer simulations and animal experiments. For in vivo studies, a MicroMed-DeBakey ventricular assist device (VAD) was implanted in 7 healthy sheep. Ventricular contractility was examined under normal conditions and after pharmacologic intervention. For the computer simulation, variations of ventricular contractility, ventricular pre-load and after-load, and pump speeds were studied.
In vivo and computer simulations showed the I(Q) index to be sensitive to changes of cardiac contractility, similar to other classic indices. For reduced cardiac contractility, it decreased to 9.3 +/- 3.9 (s(-1)) vs 15.3 +/- 4.0 (s(-1)) in the control condition (in vivo experiments). The I(Q) index was only marginally influenced by pre-load and after-load changes: a variation of 7.0% +/- 8.9% and 1.3% +/- 7.1%, respectively, was observed in computer simulations.
The I(Q) index, which can be derived from pump data only, is a useful parameter for continuous monitoring of the cardiac contractility in patients with RBP support.
SourceAvailable from: Paul MalcheskyArtificial Organs 03/2015; 39(3):199-200. DOI:10.1111/aor.12492 · 1.87 Impact Factor
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ABSTRACT: Mechanical circulatory support (MCS) is increasingly used in the end-stage heart failure patients. The rotary blood pump (RBP) is a novel technology of MCS that currently used in the left ventricular (LV) failure patient. After RBP implanted in LV, some patient immediately need another RBP on the right side of the heart. The effect of LV-RBP or left ventricular assist device (LVAD) on the right ventricle (RV) has been simulated in both normal RV and pathology RV for education proposes. This simulation was regulated the pathology of the heart from normal heart (Maximum Elastance; Emax: 100%) to pathological heart (Emax: 50%) and the level of RBP support in the LV (partial support and full support). The result of this simulation showed the hemodynamics during LV-RBP support. The end-diastolic volume of left ventricle was depended on pump speed. The increasing of right ventricular volume during support was showed in the pathological RV. In contrast, the remaining of right ventricular volume during support was showed in the normal RV. In conclusion, this computer simulation can re-generated the hemodynamics and pressure-volume loop heart failure patient with MCS.Biomedical Engineering International Conference (BMEiCON), 2012; 01/2012
Conference Paper: Development of pressure estimation for external rotary blood pump[Show abstract] [Hide abstract]
ABSTRACT: The improvement of heart function are the important consideration for heart failure patient with rotary blood pump (RBP). The capable of function evaluation depend on good monitoring system, which facilitate the physician for diagnosis. In this study, pressure estimation from measured flow rate for the patients with external RBP support is implemented with the non-invasive technique for cardiac function assessment. Measured flow rate from our mock circulation experiment at difference rotational speeds were used to apply with a notable RBP models. Our purpose is to find the optimal parameter values for pressure estimation from our RBP prototype. MUPD-VAD02 that is the external rotary blood pump for pediatric patients was used in this study. The suitable model for our pump prototype is the linear pressure - flow characteristics relationship with speed dependent resistant (Rp), which appeared linear correlations between estimated and measured pressure in a slope of 0.96 (R2 = 0.9603). In conclusion, the parameters and modified RBP model for pressure estimation of MUPD-VAD02 is developed.Biomedical Engineering International Conference (BMEiCON), 2013 6th; 01/2013