Comparing The Effects Of Right Ventricular Apical And Septal Pacing On QRS Wave Duration And Waveform

Objective: To compare the effect of the right ventricular apex（RVA）and right ventricular septa（lRVS） pacing on the QRS wave duration andwaveform, and explore a better pacing site.Methods: We collected92hospitalized patients with permanentpacemakers from January,2014to December,2014in the Department ofCardiology of the2nd Hospital of Jilin University. They were diagnosedas sick sinus symptom（SSS）（n=53cases） or high-degree（third-orsecond degree type2） atrioventricular block（AVB）（n=34cases）andimplanted permanent pacemaker, including54males and38femaleswith an average age o（f68.1±9.5）years old. They were divided into RVApacing group（n=44cases）, right ventricular high septal (RVHS) pacinggroup（n=25cases）and right ventricular low septal (RVLS) pacing group（n=24cases）according to the different ventricular pacing site. Theelectrocardiograms were recorded within24hours after the surgery. Toanalysis the QRS wave duration, the vector direction and R waveamplitude of limb leads, the R wave’s transition of precordial leads, andget the frontal plane axis from the vector direction and amplitude of I andIII leads.Results: Compared with the preoperative, the QRS wave durationwas significantly prolonged in RVA pacing group, RVHS pacing groupand RVLS pacing group (153.6±11.2ms,133.3±8.9ms,138.4±11.5ms,respectively). The difference was statistically significant (P<0.05). TheQRS wave duration of RVHS pacing group and RVLS pacing group was significantly shorter than RVA pacing group (P<0.05). The difference wasnot statistically significant between RVHS pacing group and RVLSpacing group.The QRS waveforms of the six frontal plane leads were more variousin RVS pacing group than RVA pacing group. In RVS pacing groups,main wave directions of28patients (58.3%) were in accordance with thatof preoperative in5or more than5leads. The main wave directions of II,III, aVF leads were all negative in RVA pacing group. The difference wasstatistically significant (P<0.05) in the RVS pacing group and RVA pacinggroup.The ECG showed CLBBB in both RVS pacing group and RVApacing group. The frontal axis of ECG in RVA pacing group was leftdeviation. The R wave transition was rarely seen in precordial leads, andthe main wave directions of QRS waveform were all downward at II, III,aVF leads, which were completely opposite with normal main wavedirections. However, in RVS pacing groups the R wave transition wascommon in precordial leads, and the QRS waveform were variable, inwhich the main wave directions were uncertain. The frontal axis of ECGwas no deviation or right deviation lightly in RVHS pacing group, and nodeviation or left deviation lightly in RVLS pacing group. The ECGcharacteristic of the RVHS was prominent, in which the main wavedirections of QRS waveform were all upward at II、III、aVF leads, theQRS waveform was in different shapes such as M, r, rs, QS in I lead，buttheir amplitudes were all less than0.5mV.Conclusion: The QRS wave duration of RVS pacing group wassignificantly shorter than RVA pacing group. The main wave directionswere more consistent in RVS pacing group than in RVA group. RVS was the more ideal pacing site which was closer to the physiological pacingsite than RVA. RVHS was easier to locate than RVHS by ECG combiningwith X-ray, which because the ECG characteristic of RVHS wasprominent.