Background : The left atrial appendage (LAA) has been reported to be a key contributor to the maintenance of atrial fibrillation (AF). High dominant frequency (DF) sites detected by fast fourier transform (FFT) analyses are known as electrical substrates for AF. We therefore investigated the association between the LA body and LAA volumes and DFs in for the sequence of AF ablation. Methods and Results : Multi-slice CT was performed in 46 AF patients (paroxysmal 27 ; persistent 19) who underwent catheter ablation. Before the ablation, the LA and LAA volume were measured, and the LA and LAA DF value during AF was calculated. AF was no longer inducible after the pulmonary vein isolation (PVI) in 27 patients (PVI responders) whereas it was still inducible in the remaining 19 (PVI nonresponders). Among the PVI nonresponders, a PVI plus complex fractionated atrial electrogram (CFAE) ablation and/or LA linear ablation terminated the AF in 7 patients (LA-ABL responders), but did not in 12 (LA-ABL nonresponders). The PVI nonresponders had a larger LA volume (121.8±7.2mm³ vs. 98.8±7.1mm³, p=0.0285) and modestly larger LAA volume than the PVI responders (14.4±1.0mm³ vs. 12.3±1.0mm³, p=0.1399). The LA and LAA DF values significantly increased in the PVI nonresponders compared to the PVI responders (LA : 6.8±0.2Hz vs. 6.1±0.2Hz, p=0.0429 ; LAA : 6.7±0.2Hz, vs. 6.0±0.2Hz, p=0.0164). Among the PVI nonresponders, the LAA volume was significantly larger in the LA-ABL responders than in the LA-ABL nonresponders (17.1±1.4mm³ vs. 11.6±1.2mm³, p=0.0102), but there was no difference in the LA volume (126.7±12.4mm³ vs. 111.9±10.5mm³, p=0.3770). Incremental increases in the LA and LAA DF values were noted in the LA-ABL responders and nonresponders (LA-DF 6.6±0.5Hz vs. 7.0±0.4Hz, p=0.4955 ; LAA-DF 6.3±0.4Hz vs. 7.0±0.3Hz, p=0.2122). Conclusions : Patients who responded to the PVI had a smaller LA volume and lower DF value in the LA and LAA. In patients refractory to PVI, a larger LAA volume and relatively lower LAA DF value might be a useful indicator for AF termination by additional CFAE/linear ablation in the LA.

View full abstract

Discrepancies in of amplitudes of intracardiac electrograms are often observed between pacing system analyzers (PSA) during implantation and programmer just after the operation. We conducted this study to clarify the reason for this phenomenon. The study subjects were 80 patients who underwent pacemaker implantation or replacement. Their mean age was 78 years old, and 38 were males. Amplitudes of intracardiac P and R waves were measured and compared by using PSA during implantation and by programmers of specific manufacturers just after the operation. Furthermore, we performed a simulation to measure and compare artificial P and R waves by PSA and programmer. No significant difference was found in the measurement of R wave. On the other hand, the amplitude of P wave measured by the programmers was significantly higher than its amplitude when measured by PSA. We also found that this gap differed depending on the manufacturer. This tendency was still observed even in 24 patients who underwent generator replacement. The results of simulation supported these findings, and we concluded that the peculiar settings of sensing filters of PAS and programmers may play a role in these differences. We should pay attention to the difference in the amplitude of intracardiac electrograms, especially P wave, when measured by PSA and programmers.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract