927 PDMI in evaluation of dispersion of electric impulses generated by a cardiac pacemaker dependent on the location of the ventricular lead

Abstract

s S157 Eur J Echocardiography Abstracts Supplement, December 2006 927 PDMI in evaluation of dispersion of electric impulses generated by a cardiac pacemaker dependent on the location of the ventricular lead A. Drzewiecka 1; R. Mlynarski 1; E. Pilat 1; W. Kargul 1 1Medical University of Silesia, Electrocardiology Dept., Katowice, Poland New methods in echocardiography as Pulsed Doppler Myocardial Imaging (PDMI) has evolved as a well-established tool for the noninvasive evaluation of myocardial function. There are many controversies on optimal placement of the lead in the right ventricle (RV). PDMI can be a good indirect tool to evaluate dispersion of the electric impulses in the myocardium. Purpose of the study was the comparison of the track and time of dispersal of electric impulses generated by the pacemaker in the myocardium using the PDMI method dependent on location of RV lead. Methods: Bioethical agreement No NN-6501-22/05 was obtained. 45 patients were included into the trial with sinus node dysfunction (SND) syndrome, EF >50% and without contractility disturbances. All patients were divided into 3 equal groups depending on location of the RV lead: RV outflow tract (RVOT), interventricular septum (IVS) and apex. Location of the lead was confirmed by fluoroscopy and ECG. Time of dispersal of electric impulses in myocardium was evaluated by PDMI using Vivid 7 ultrasound system (GE). In each patient 2 full examinations including isovolumetric contraction time (IVC) were performed: 1 during native rhythm and 2 on artificial rhythm after reprogramming of the pacemaker on the VDD program to exclude the influence of atrial pacing. Results: Middle values of ICT differences between native and pacemaker impulse in particular walls in ms are presented in the table below. Differences in values RVOT vs apex and RVOT vs IVS were statistically significant (p<0.05). Difference in IVS vs apex were not significant (p=0,12), although it is possible to see a positive trend of apex location in the direction of the lateral and posterior wall of the LV and RV wall. Conclusion: 1. Location of the lead has influence on time of distribution of electric impulses in the myocardium. 2. RVOT can be the most optimal location of the pacemaker lead. 3. What is very surprising is that apex location seems to be a better alternative than IVS for RV pacing. Table 1. Difrences in IVC time* LEAD LOCALIZATION RV WALL IVS1 LATERAL ANTERIOR POSTERIOR in RIGHT VENTRICLE WALL WALL WALL RVOT2 12.1 ms 29.3 ms 23.6 ms 12.9 ms 22.9 ms IVS1 47.5 ms 41.7 ms 50.9 ms 42.5 ms 58.3 ms APEX 36.0 ms 39.0 ms 41.0 ms 47.0 ms 53.0 ms * IVC=Isovolumetric Contraction Time. 1 IVS=Interventricular Septum 2 RVOT=RV outflow tract