| Objective: We aimed: (1) to investigate the electrophysiologic characteristics of right atrial wave amplitude; (2) to evaluate the differences between A-wave amplitude during sinus rhythm and f-wave amplitude during atrial fibrillation, and the feasibility of atrial lead implantation during atrial fibrillation.Methods: The subjects were 13 consecutive patients who underwent electrophysiologic studies and radiofrequency catheter ablation. Their age ranged from 34 to 84 years (mean SD, 56.08 13.26). 11 patients with the history of paroxysmal atrial fibrillation (PAF) (7 5 years) and 2 patients without the history of PAF discontinued all cardioactive medications at least 5 half-life periods before the procedure. One of the 2 was manifest Wolff-Parkinson-White syndrome and the other was concealed Wolff-Parkinson-White syndrome, and the 2 accessory pathways were both located in the left atrium. Programmed stimulation was carried out from HRA, and A 300-350 ppm stimulus within the right atrium during electrophysiologic studies gave rise to PAF.Before the procedure, all patients gave informed consent. A quadripolar 6F catheter electrode with an interelectrode distance of 1-cm was inserted percutaneously into the femoral and subclavian veins and into the right atrium under fluoroscopic guidance. 6 sites within the right atrium, including high right atrium, middle right atrium, low right atrium, high right septum, middle right septum and coronary sinus, were involved in these studies. The location of the catheter electrodes were confirmed by at least 2 experienced electrophysiological physicians who observed the multiplane fluoroscopic images and the catheter stability was documented by fluoroscopy.For each patient, the endocardial electric potentials were measured from the distal electrode pair of the quadripolar catheter with Medtronic PSA 5311 (Medtronic Inc., Minneapolis, MN, USA.) during both sinus rhythm and atrial fibrillation. A total of at least 10 atrial potentials were measured at any site each time.Values are expressed as mean standard deviation. The amplitude of each site during sinus rhythm and during atrial fibrillation was compared using Student's test for paired data. A level of P<0.05 was considered to be statistically significant.Results: 1.The mean bipolar atrial amplitude was 5.01 2.35 mV at HRA and5.41 1.60 mV at HRS during sinus rhythm, and was 3.93 1.84 mV and 3.96 1.35 mV respectively during atrial fibrillation, which was higher than that at other sites. 2.The fluctuation of A-wave amplitude during sinus rhythm(4.29 1.44mV~2.88 1.17mV, P= 0.09) is smaller than that of f-wave amplitude during atrial fibrillation (3.73 1.22mV~ 1.85 0.68mV, P=0.008). 3. During atrial fibrillation, there is significant difference between the potential of MRA and HRA, as well as that of MRA and LRA (3.93 1.84 mV vs. 1.72 0.82 mV, 3.93 1.84 mV vs. 2.08 1.09 mV, P<0.05). The difference between the potential of MRS and HRS is also significant (3.96 1.35mV vs. 2.39 0.95mV, P<0.05). 4. The mean of the amplitude of f-wave is inferior to that of A-wave. The statistical difference is significant (2.72 0.96mV vs. 3.58 1.31mV, P= 0.002).Conclusion: l.The atrial wave amplitude varies at different sites, and it is higher at HRA and HRS than that at other sites. 2. The fluctuation of A-wave amplitude during sinus rhythm is smaller than that of f-wave amplitude during atrial fibrillation. 3. During atrial fibrillation, there is significant difference between the potential of MRA and HRA, as well as that of MRA and LRA. The difference between the potential of MRS and HRS is also significant. Maybe there is a reentrant cycle here which can serve as the targets of RFCA. 4. There is higher f-wave amplitude at HRA and HRS which maybe sever as the position for the atrial lead fixation implantation during atrial fibrillation. |
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