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

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

RT-86

Oxygen uptake kinetics related to maximizing left ventricular stroke volume modifying the contraction sequence at optimal atrio-ventricular interval in dual chamber paced patients

Gabriello Marchetti, Graziana Labanti, Ennio Talamonti, Giancarlo Carini, Stefano Urbinati, Giuseppe Pinelli.
Unita Operativa di Cardiologia, Ospedale Bellaria, Bologna, Italy

Abstract

The aim of the study is to investigate by noninvasive tests (echocardiography and cardiopulmonary test) the relationship between atrio-ventricular delay (A-V delay), diastolic filling pattern, homogenization of left ventricular contraction and systolic function in patients with DDD pacemaker.

METHODS. Fifteen patients, mean age 73 years, (9 with hypertension; 1 with ischemic cardiomyopathy; 1 with diabetes; 4 without organic diseases) with II degree A-block (8 patients) and III degree A-V block (6 patients), were implanted with PODD. They were studied by echocardiography in order to determine systolic function (stroke volume), diastolic and systolic volumes, diastolic filling pattern (E wave, A wave and E/A ratio) with pulsed Doppler, and sincronicity and homogeneity of left ventricular function at intervals of 200-150-100 msec of the A-V delay they were also evaluated every 3 months with cardiopulmonary test in order to assess oxygen uptake kinetics. Oxygen deficit was determined by the Whipp formula: t x delta VO₂- summatory VO₂, whereby t is time from rest to steady state (min); delta VO₂ is the sum of VO₂ from rest to steady state (ml).

RESULTS. A shortening of A-V delay in most patients give an enhance of E/A ratio, but the optimum A-V delay individually determined not always corresponds to the best homogeneization of left ventricular systolic pattern (septum, free wall and apex), systolic function and oxygen kinetics.

Difference between worse and better A-V delay for each patient gives a statistically significant difference of stroke volume (33.25 ml versus 56.7 ml) and oxygen deficit during cardiopulmonary test (1146.8 versus 612 ml).

CONCLUSION. In DDD patients, if the A-V delay is adapted individually for diastolic function and uniformity of left ventricular contraction, it’s possible to observe an increase of systolic function at rest and during moderate effort as confirmed by the oxygen kinetics.

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