Usefulness of Doppler tissue imaging for the assessment of right and left ventricular myocardial function in patients with dual-chamber pacing

The aim of the study was to evaluate by Doppler tissue imaging (DTI) the co mbined effects of atrio-ventricular (AV) delay and heart rate (HR) changes on global and segmental right (RV) and left (IV) ventricular diastolic func tion in 15 patients with dual-chamber pacemakers paced in the DDD mode. RV and IV inflow velocities and regional systolic and diastolic pulsed-wave (P W) DTI parameters were analyzed at four different pacing modes: (1) HR 70 b eats/min, AV delay 125 ms; (2) HR 70 beats/min, AV delay 188 ms; (3) HR 89 beats/min, AV delay 125 ms; (4) HR 89 beats/min, AV delay 188 ms. For each pacing mode selected, RV diastolic filling velocities always prevailed over IV ones. As for RV and IV adaptation to the four different stimulation pro tocols, a higher paced rate and a prolonged AV delay caused across both the AV valves a decrease of E wave and of E/A ratios. The intersegmental compa rison of PW-DTI parameters outlined that RV free wall exhibited significant ly higher peak systolic (Sm) and early-diastolic (Em) wall velocities, and longer systolic ejection time. Considering separately RV and IV segmental p hysiology at the four pro-rammed pacing modes, an increase in HR determined a progressive shortening of systolic ejection times in all the segments an alyzed. Moreover, in each region the Em/Am ratio decreased with higher HR a nd longer AV delay. Conversely, Em encountered a progressive reduction in R V free wall, while remaining quite unchanged in all the IV regions. Both ve ntricles shared a similar pattern of global and regional adaptation to prog rammed HR and AV delay modifications, consisting in a progressive greater c ontribution of late diastole to ventricular filling at higher HR and more p rolonged AV delay. However, at a regional level the right ventricle exhibit ed higher systolic and diastolic wall velocities than all left ventricular regions. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.