###### Abstract  
This study assesses the electric current parameters and reports on the analysis of the associated degree of myocardial function during left ventricular assist device (LVAD) support. An assumption is made that there is a correlation between cardiac output and the pulsatility index of the pump electric current. The experimental study is carried out using the ViVitro Pulse Duplicator System with Sputnik LVAD connected. Cardiac output and cardiac power output are used as a measure of myocardial function. Different heart rates (59, 73, 86 bpm) and pump speeds (7600-8400 rpm in 200 rpm steps) are investigated. In our methodology, ventricular stroke volumes in the range of 30-80 mL for each heart rate at a certain pump speed were used to simulate different levels of contractility. The correlation of the two measures of myocardial function and proposed pulsatility index was confirmed using different correlation coefficients (values \(\geq\) 0.91). Linear and quadratic models for cardiac output and cardiac power output versus pulsatility index were obtained using regression analysis of measured data. Coefficients of determination for _CO_ and _CPO_ models were in the ranges of 0.914-0.982 and 0.817-0.993, respectively. Study findings suggest that appropriate interpretation of parameters could potentially serve as a valuable clinical tool to assess myocardial therapy using LVAD infrastructure. heart failure; left ventricular assist device; myocardial function; mechanical circulatory support +
Footnote †: journal: Applied Sciences  
the technology advances, instrumentation for proper evaluation of ventricular function becomes crucial in developing LVAD treatment and explantation strategies for improving patients' outcome. In past decades, the development of automatic or physiological LVAD control methods was intensively carried out by many research groups. These methods are aimed to automatically regulate pump speed in response to changes occurring in the cardiovascular system (CVS) during support, and to changes in ventricular function in particular. Multiple reports on pulsatility measures of different pump characteristics (flow rate, pressure head, electric current, power consumption) proposed to implement automatic pump control strategies were provided [11; 12; 13; 14; 15; 16]. Mainly, different indices of pump flow rate are used as a pulsatility measure [11; 12; 14; 15; 16]. Besides, the pulsatility index of pump motor current was used to determine the safety range of LVAD speed to avoid valve regurgitation and suction state of the ventricle during support [13]. Relations of pulsatility measures to residual ventricular contractility and preload were also shown in the listed reports. Unfortunately, proposed methods of physiological control have a number of shortcomings impeding their actual use in clinical practice. Although the clinical implementation of physiological pump control remains an unsolved and complex task, there is still an opportunity to introduce a simpler additional noninvasive tool for clinical hemodynamic assessment in heart failure patients with LVADs implanted. Such tools are can be included in the LVAD controllers and providing medically clear parameters that evaluate myocardial function, which may be used along with other tools applied in clinics like echocardiography. It may also be utilized for outpatient monitoring of myocardial function, in particular for the detection of possible cardiac recovery. The development process of such tools can be started at the determination of the relationship between myocardial mechanical function and readily available LVAD intrinsic parameters, such as the pulsatility index of the pump electric current, since it was shown to have a relationship with left ventricular contractility [13; 17]. In this study, we aim to assess the pulsatility of the pump electric current and report on the analysis of the associated degree of myocardial function during LVAD support.