Abstract
To assess the acute side-effects of right ventricular (RV) stimulation applied in apex and mid-septum, in order to establish the optimal lead location in clinical practice. During pacemaker implantation, the ventricular lead was temporarily fixed in the apex and then moved to mid-septum. In both positions, surface and endocardial electrograms and transvalvular impedance (32 cases), left ventricular (LV) pressure (23), and transthoracic echocardiography (10) were acquired with intrinsic activity and VDD pacing. A larger increase in QRS duration was noticed with apical than septal pacing (65±25 vs. 45±29 ms; P<10(-4)). The proportion of cases where RV stimulation affected the transvalvular impedance waveform was higher with apical lead location (56% vs. 20%; P<0.02). VDD pacing at either site reduced the maximum dP/dt by 6% with respect to intrinsic AV conduction (IAVC; P<0.005). The maximum pressure drop taking place in 100 ms was reduced by 6 and 8%, respectively, with apical and septal pacing (P<0.01 vs. IAVC). Apical VDD decreased mitral annulus velocity in early diastole (E') from 7.5±1.4 to 5.9±0.9 cm/s (P<0.02) and prolonged the E-wave deceleration time (DT) from 156±33 to 199±54 ms (P<0.02), while septal pacing induced non-significant modifications in E' and DT. Ventricular stimulation acutely impairs LV systolic and diastolic performance, independent of the pacing site. Septal lead location preserves RV contraction mechanics and reduces the electrical interventricular delay.
Highlights
Electrical stimulation of the ventricle is mandatory to restore properly timed activity in patients affected by atrioventricular block (AVB)
The effects of the activation pattern switch on left ventricular (LV) pressure, cardiac electric signals and transvalvular impedance (TVI) were assessed after 3-min stimulation
Electrical synchronization In each patient, the ventricular activation modality was switched from intrinsic AV conduction (IAVC) to VDD stimulation with the ventricular lead sequentially positioned in both right ventricular (RV) apex and mid-septum
Summary
Electrical stimulation of the ventricle is mandatory to restore properly timed activity in patients affected by atrioventricular block (AVB). With the energy normally used for pacing purposes, the electric pulse directly excites just a small portion of the ventricular myocardium, restricted to about 1 mm in case of point stimulation by a very small electrode[1]. Milder effects on ventricular synchronization and pump function have been associated with right ventricular (RV) pacing applied in alternative sites, like the mid-septum or the outflow tract[2,8,9,10]. These claims might have a significant impact in the clinical setting[11], as pacing lead positioning in the RV apex is still normal practice in many implantation centres
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
