The Correlation Between Right Ventricular Electrode Implant Site And The Surface Electrocardiogram QRS Morphology

Background：The role of right ventricular apical pacing in the atrioventricular orbiventricular systolic dyssynchrony was been investigated in the pacing site-relatedresearch recently. Selective pacing sites was hoped to make the right ventricular apicalpacing-induced ventricular asynchronism minimized. A growing number of clinicalstudies have found that different pacing sites were closely related to long-termprognosis of patients. Although the cardiac CT, ultrasound and other imaging meansmight provide more information about the the electrode implant site, they are notfeasible during operation. This study aimed to find the most ideal QRS morphology,duration, electrical axis by the conventional X-ray method.Methods:450consecutive patients who were diagnosed sick sinus syndrome (sss),atrioventricular block (AVB) and atrial fibrillation along with long R-R pause betweenJan2012to Aug2013accepted pacemaker implantation in our hospital were enrolled.We measured the QRS duration, amplitude, axis, and investigate the likelihood of rightventricular pacing before and after operation.Then we divided the right ventricularseptum into nine pacing district witch named A to I from left to right and from top tobottom in sequence by the3×3grid positioning method under right anterior oblique30°. The QRS duration, amplitude, axis,and the likelihood pre-and post-implantation under different pacing sublocations were investigated.Results:450patients,226male and224female, were enrolled in this study.(1) QRSduration was different in different pacing sublocations. The QRS duration was theshortest in location e (102.89±33.36ms), then in location b (104.17±17.82ms),location f(108.80±29.26ms), location h (136±36.06ms), and location i(151.81±28.17ms). QRS duration shorten is most significant in location e than the other fivelocations after pacing (13.99±18.77%,P=0.01). After pacing,e area has a minimumincrease range in5areas(13.99±18.77%), but i area owns the maximum increaserange(P=0.01).(2) The migrations of precordial QRS wave were different: The ratio ofR/S<1in lead V4were different: It is most often in location e(76.6%),then locationb(83.3%), location f(88.2%), location i(90.6%) and location h(100%) which showd veryhigh sensitivity.(3) The left axis deviations were detected in lacationi(-60.23±26.05°)and location h (-23.21±25.00°), and the left axis deviations were notobvious in location b(100.34±4.02°),e(45.00±30.15°) and f(76.21±34.01°).h and i aresignificant differences to other three locations(P=0.01).Conclusion: The locations b and e in the3×3grid figure are relatively optimal pacingsites: The QRS duration are narrowest,cardiac axis don’t change significantly postpacing; the proportion of R/S migration after V4lead are minimum,moreover,QRSwave likelihood pre-and post-implantation in nine pacing sublocation are the most idealof these two pacing sublocations.