Contributions of a hemodynamic sensor embedded in an atrial lead in a porcine model

Preliminary studies have revealed a high correlation between peak endocardial acceleration (PEA) measured with a sensor embedded in a ventricular lead and human cardiac contractility. In this study we assessed (1) the contributions made by measurements of PEA1, an index of ventricular systolic contraction, from the right atrium, and (2) the feasibility of recording a fourth component of PEA (PEA4), coincident with atrial contraction and corresponding to the phonocardiographic fourth heart sound.

We placed a PEA sensor embedded at the tip of a right atrial lead in 9 pigs. A 7F Millar catheter tip micromanometer was introduced into the left ventricular (LV) cavity to measure dP/dt(max). Myocardial contractility was increased by infusion of dobutamine and depressed by the infusion of esmolol. We searched, during VDD pacing, for PEA4 following atrial systole, while gradually lengthening the atrioventricular delay. Ventricular fibrillation was then triggered by rapid stimulation.

The changes in PEA1 were correlated with the changes in LV dP/dt(max) (r = 0.91; P < 0.001). A low-frequency component of the endocardial signal (PEA4) was visible approximately 50 milliseconds after the atrial electrogram in all experiments. Following the induction of ventricular fibrillation, PEA4 remained visible on the endocardial recording, simultaneous with the sensed atrial electrogram.

This study confirms the merit of embedding a PEA sensor in an atrial lead. The exploitation of the information provided by the PEA1 signal remains pertinent and the possibility to record an additional PEA4 component offers the perspective of new clinical applications.