14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-51

Peak endocardial acceleration: a new physiologic sensor

A. Colella, L. Padeletti, M.C. Porciani, A. Costoli, A. Michelucci, P. Pieragnoli, P. Ritter*, H. Luttikhuis**, G. Gaggini***, G.F. Gensini.
Dept. of Internal Medicine and Cardiology, University of Florence, Florence, Italy, *InParys, Paris, France, **Sophia Hospital, Zwolle, The Netherlands, ***Sorin Biomedica Cardio, Saluggia, Italy

The applications of peak endocardial acceleration

In the last years, pacing indications have noticeably enlarged entering areas like supraventricular tachyarrhythmias, dilatative or hypertrophic cardiomyopathies.

A variety of pacing approaches has been proposed, and has been clinically tried, for the prevention and for the treatment of these pathologies. The intrinsic complexity of these syndromes, largely greater than that of pure rhythm disturbances, underlined the potential role of implantable sensors for long-term monitoring of overall heart function.

PEA has been applied as a haemodynamic sensor in a series of studies, devoted to the validation of its possible role in different clinical areas.

AV delay optimization

It is well known that optimisation of AV delay is of most importance, from a haemodynamic point of view, in patients with high degree AV block. In clinical practice to evaluate the AV interval the ECHO is still the most commonly used non-invasive test but it is time consuming and possible only at rest. Previous study showed the effect of AV interval variations on the first heart sound and PEA: the signal is maximised when there is competition between atrial and ventricular contractions and decreases down to a plateau when the AV delay (AVD) is progressively prolonged. The AVD at the beginning of the plateau has been identified as the optimal one, as a sign of the natural completion of the atrial systole.

In 19 patients with high degree AV block the optimal AVD obtained by PEA evaluation has been compared with the one obtained by ECHO, as the one which corresponds to the maximum LV diastolic filling time, without interruption of the A wave³.

The results show that:

–PEA and ECHO evaluations lead to similar AVD values (Tab. I);

–optimal AV delay may be obtained directly from an implanted device making in this way possible to optimise it also under effort.

A multicentric study on this application of PEA as a haemodynamic sensor is in progress.

The study focuses on the dependence of optimal AV delay with effort level, in the perspective of developing an automatic AV delay adapting algorithm.

TABLE I–Comparison between optimal AVD obtained by PEA and ECHO

Comparison of apical vs right ventricular outflow tract stimulation

Whether stimulation in the right ventricular outflow tract (RVOT) is better than pacing in the and right ventricular apex (RVA) in terms of haemodynamic performances is still under evaluation. It was proposed to use PEA in a prospective, randomised and single blind study, to evaluate contractility in the long-term follow-up of patients paced in RVOT and RVA.

In 13 patients with chronic atrial fibrillation, high degree AV block or RF ablated AV node a DDDR pacemaker able to measure PEA has been implanted. The RVOT screw-in lead was connected to the atrial port and the sensor equipped lead was connected to the ventricular port. This setup allowed to pace separately the two sites, contemporarily measuring PEA signal and the contractility.

The results (Tab. II) achieved after 1 year of follow-up show that pacing in RVOT significantly improves left ventricular contractility (PEA and PEI) and haemodynamic indexes (CO)4. Thanks to this data, PEA can be considered a valid parameter for monitoring of the heart overall contractile function.

PEA vs mental stress

This clinical study aimed to evaluate if tests, that are able to increase the adrenergic tone, may lead to an increase of PEA signal similar to that of sinus rate.

Eleven patients underwent three tests: mental stress (MS), cold pressure test (CPT) and isometric hand grip (IH). The data showed a strict correlation between the variation of PEA and sinus rate during the three tests: r=0.95 in MS, r=0.92 in CPT, r=0.96 in IH⁵. These results suggest that PEA can be considered a true “physiologic” sensor able to simulate the behaviour of the heart during different situations.

TABLE II–Comparison RVA vs RVOT pacing