Yoshifumi Ikeda

The influence of the electrodes spacing of a mapping catheter on the atrial voltage substrate map

BACKGROUND Detailed substrate mapping is important for catheter ablation. However, the influence of the electrode spacing of the mapping catheter on the substrate map has not been well clarified. The aim of this study was to investigate the influence of the electrode spacing of the mapping catheter on the voltage of the substrate map. METHODS Protocol 1: We recorded the local atrial potentials of the left atrium (LA) using the ablation catheter during sinus rhythm in six atrial fibrillation (AF) patients. The voltage of each atrial potential was compared between a close-bipolar (1-2 electrode) recording and wide-bipolar (1-4 electrode) recording. Protocol 2: Two voltage-maps of the LA were constructed separately using a 20-pole circular catheter and 10-pole circular catheter during sinus rhythm in 42 AF patients. The low voltage zone (LVZ) (<0.5mV) areas obtained by 2 voltage maps using the 10-pole and 20-pole circular catheters were compared. RESULTS Protocol 1: The close-bipolar voltage of the local potentials was significantly smaller than that of the wide-bipolar voltages (0.76±0.39mV vs. 0.63±0.41mV, p<0.0001). Protocol 2: The size of the LVZ areas identified by the 10-pole and 20-pole catheters was 1.12±1.92cm2 (1.47±2.78%) and 8.30±7.80cm2 (8.83±8.32%), respectively (p<0.0001). CONCLUSIONS The voltage of the local atrial potential using the close-bipolar catheter was significantly smaller than that using the wide-bipolar catheter. Care should be given to the electrode spacing of mapping catheters when analyzing the voltage of the atrial myocardial potentials.

Analysis of the heart rate variability during cryoballoon ablation of atrial fibrillation

Aims Vagal responses such as marked bradycardia or a rapid blood pressure decrease are often observed during pulmonary vein (PV) isolation of atrial fibrillation (AF) using a cryoballoon (CB). However, the relationship between the marked vagal response and change in the heart rate variability (HRV) as a marker of the autonomic tone is not well understood. Methods and results Fifty-four paroxysmal AF patients underwent CB ablation. The CB ablation was started from the right sided PVs in 25 patients (R group) and left sided PVs in 29 (L group). The HRV and haemodynamic status during the procedure were analysed. A vagal response was observed in 16 L group patients (61.5%) during the ablation of the different PVs (RSPV:1, RIPV:5, LSPV:15, LIPV:5), while it was observed in only 2 R group patients (9.5%) (RSPV:0, RIPV:0, LSPV:1, LIPV:1) (P = 0.0002). The HRV in the L group was significantly higher than that in the R group just after the CB ablation especially for the left sided PVs (L group vs. R group, total power of the HRV, median; RSPV, 11184.7 vs. 4360.0, P = 0.21; RIPV, 9044.3 vs. 2115.1, P = 0.01; LSPV, 21186.0 vs. 1314.2, P = 0.0002; LIPV 10265.9 vs. 1236.2, P = 0.0007). Conclusion A marked increase in the HRV parameters was observed just after the CB ablation. An initial CB ablation of the right PVs decreased the change in the autonomic tone during the right PV ablation and subsequent left PV ablation. It prevented an excessive vagal response during the CB ablation and might be a safe procedure.

P-75 Heart Transplantation in Patients with Diabetes Mellitus

Heart transplantation is the most effective therapy for endstage heart failure of diabetes mellitus. There are very few cases who underwent heart transplantation in Japan because DM remains a relative contraindication for heart transplantation. We enrolled 45 patients in Japan Organ Transpant Network, but there was only one patient with DM. Nevertheless, the increasing prevalence of both DM and congestive heart failure makes it necessary to perform heart transplantation in near future. We performed a retrospective analysis on long-term survival in 453 patients with DM who underwent heart transplantation at Heart and Diabetes Center NRW Bochum University in Germany. Survival rate and causes of death were compared with data of a group heart transplant recipients without DM. Mean follow-up time of all heart transplant recipients was 68.2 months (range: 0 204 months). Overall mortality during follow-up was 42.9%. Long-term survival did not differ significantly between study groups (P= 0.32). In addition, there was no significant differences in survival rates between groups with advanced DM and without DM. Steroid-free immunosuppressive therapy was associated with a higher percentage of long-term survivors compared with no steroid-free immunosuppression. Our data demonstrate that long-term survival is acceptable in heart transplant recipients with preoperatively diagnosed DM.