A novel implantable sensor to monitor both apical rotation and cardiac phases

Objectives: The magnitude and timing of Left Ventricular (LV) twist with respect to cardiac phases are essential to detect systolic and diastolic dysfunction, as recently shown by advanced imaging techniques. No implantable sensors are currently available to provide that phasic analysis of LV rotation over the cardiac cycle. We developed and evaluated in a sheep model an innovative implantable gyroscopic sensor for the continuous endocardial monitoring of both the amount and timing of cardiac rotation. Methods: In a sheep, a tip catheter gyroscopic sensor was inserted in the endocardium of the right ventricle apex. The detected signal (EndoTwist) was continuously recorded along with ECG, LV pressure (LVP) and its first derivate (LVdP/dt). EndoTwist was processed in order to obtain both cardiac rotation parameters (twist rate ω, apical rotation angle θ) and mechanical heart vibrations (MHVs) used to identify systole and diastole. Results: The detected EndoTwist signal clearly showed both a low-frequency component relating to cardiac rotation (ω, θ) and a high frequency component relating to MHVs. Identification of systole and diastole from MHVs was confirmed by comparison with LVdP/dt which was previously used to define the timing of the cardiac cycle. Conclusions: The new implantable sensor permits detection of cardiac twist dynamics (ω, θ) with respect to the entire cardiac cycle by means of MHVs recognition. This information, if confirmed in larger studies, has promising clinical implication for the monitoring of cardiac function in heart failure patients.