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

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

RT-131

Effects of different modes of programmed DDD pacing on regional diastolic function: a pulsed-wave Doppler tissue imaging study

Antonello D’Andrea, Valentino Ducceschi*, Barbara Mercurio, Francesca Panico, Salvatore D’Isa, Pio Caso**, Berardo Sarubbi*, Gerardo Nigro, Biagio Liccardo, Lucio Santangelo, Aldo Iacono, Maurizio Cotrufo.
Universita Napoli, *Dottorato di Ricerca in Scienze Cardiologiche e Cardiochirurgiche - Seconda Universita Napoli, **Azienda Ospedaliera Monaldi, Napoli, Italy

Abstract

BACKGROUND. Aim of our study was to evaluate by pulsed-wave tissue Doppler echocardiography (TDE) the combined effects of atrioventricular (AV) delay and heart rate (HR) changes on segmental right and left ventricular diastolic function in patients paced in the DDD mode.

METHODS. We enrolled a population of 13 subjects with dual-chamber pace-makers paced in the DDD mode for AV block and/or sick sinus syndrome. Right and left diastolic PW-TDE parameters were analyzed at four different pacing modes: 1) HR 70 beats/m’ - AV delay 125 msec; 2) HR 70 beats/m’ - AV delay 188 msec; 3) HR 89 beats/m’ - AV delay 125 msec; 4) HR 89 beats/m’ - AV delay 188 msec.

RESULTS. The intersegmental comparison of PW-TDE parameters outlined that right ventricular free wall exhibited significantly higher early (Em) and late (Am) diastolic wall velocities than all left ventricular regions, whose velocities appear very similar to each other. Furthermore, right ventricle tended to have more prolonged relaxation times with respect to all left ventricular regions. No intersegmental difference was found in terms of regional Em/Am ratios.

Considering separately right and left ventricular segmental physiology at the four programmed stimulations, Am increased and the Em/Am ratio decreased with higher HR and longer AV delay, while RTm did not significantly vary. Furthermore, Em encountered a progressive reduction in right ventricular free wall, while remaining quite unchanged in all the left ventricular regions.

CONCLUSIONS. The right site of breakthrough of the electrical impulse determines a more homogeneous activation of the right ventricle, therefore causing higher diastolic wall velocities. Segmental ventricular diastolic function adjustment to increase in HR and AV delay would reflect the global adaptation of both the ventricles to the same changes that modify preload conditions. Alternatively, given the demonstrated independence of TDE diastolic parameters from preload modifications, we may not exclude that an increase of programmed HR and AV delay might primarily affect myocardial walls diastolic motion, shifting their major distensibility to late-diastole.

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