First Experimental Evaluation of Cardiac Apex Rotation with an Epicardial Coriolis Force Sensor

Abstract

Cardiac apex rotation, quantified by sophisticated techniques (radiopaque markers and tagged magnetic resonance), has been shown to provide a sensitive index of left ventricle (LV) dynamics. The authors describe the first experimental assessment of cardiac apex rotation using a gyroscopic sensor based on Coriolis force, epicardially glued on the apex. Dynamics of apex rotation were evaluated in a sheep at baseline, after a positive inotropic drug infusion, and after impairment of cardiac function induced by coronary ligation. To evaluate the efficacy of the sensor to monitor cardiac function, results were compared to contractility variations expressed by the maximum value of the first derivative of LV pressure (LVdP/dtMAX). After inotropic drug infusion, a parallel increasing trend resulted for LVdP/dtMAX, for the maximum value of angular velocity measured by the sensor, and for apex rotation angle derived from velocity signal (+146%, +155%, and +11% from baseline, respectively), whereas a decreasing trend of all three parameters resulted after coronary ligation (-35%, -31%, and -65%). The twist pattern also was altered from baseline. These initial results suggest that the use of an implantable rotation sensor based on Coriolis force can be an efficient and effective tool to assess LV torsional deformation both in normal and failing hearts.

Effect of Right Ventricular Pacing on Cardiac Apex Rotation Assessed by a Gyroscopic Sensor

“…Results demonstrated the efficacy of the gyroscopic sensor to provide information on cardiac function as the measured Ang V signal strictly followed LVdP/dt MAX trend, during all the simulated cardiac conditions. 54 In the present study, we investigated the effect of electromechanical cardiac dyssynchrony experimentally induced by RV pacing on CAR param- eters assessed by using the same measuring technique of our first experience previously described. 54 It is well established that pacing the heart from a ventricular site results in an asynchronous contraction of the LV.…”

“…54 In the present study, we investigated the effect of electromechanical cardiac dyssynchrony experimentally induced by RV pacing on CAR param- eters assessed by using the same measuring technique of our first experience previously described. 54 It is well established that pacing the heart from a ventricular site results in an asynchronous contraction of the LV. 56 -58 The major difference between an atrially paced and a ventricularly paced beat is that the left ventricular depolarization, which occurs normally in the former, begins from an abnormal site in the latter.…”

“…54 The advantages of using a gyroscopic sensor rather than other motion sensors like accelerometers were previously described. 50 In our first animal experience, we reported results of CAR measurement with a gyroscope epicardially glued on the apex surface in normal hearts and after different induced cardiac alterations such as inotropic drug infusion and coronary ligation.…”

“…40,41 After our previous experiences with implantable cardiac devices equipped with hemodynamic sensors able to assess cardiac function [42][43][44][45][46][47][48][49] and investigations of the technological solutions offered by the market and described in scientific literature, 50 -53 we recently experimentally evaluated the use of a gyroscopic sensor based on Coriolis force (gyroscope), epicardially glued on the heart to measure cardiac apex rotation (CAR). 54 Preliminary experimental results were encouraging and gave novel stimuli toward the study of an implantable medical device equipped with the gyroscopic sensor, such as pacemakers, implantable cardioverter-defibrillators, or systems for controlled drug delivery. A long-term assessment of CAR parameters over time could allow a long-term monitoring of cardiac function, thereby providing early diagnosis of heart dysfunction and guiding optimization of the therapy.…”

Twist Mechanics of the Left Ventricle

“…Over the past 3 centuries, the twist deformation of the LV has continued to intrigue clinicians and researchers in their quest to understand the performance of human heart. Experimental and clinical explorations on LV twist have entailed use of numerous techniques such as implanted radiopaque markers (2), biplane cine angiography (3), sonomicrometry (4,5), optical devices (6), gyroscopic sensors (7), magnetic resonance imaging (MRI) (8 -10), and echocardiography (11)(12)(13)(14). Furthermore, growth of interest in the quantifying LV twist in clinical settings has resulted into development of innovative techniques in which LV twists are readily computed from grayscale cardiac ultrasound images obtained at the bedside.…”