Rate-dependent slow conduction velocity in the cavo-tricuspid isthmus and septum in patients with atrial flutter / 中国医学科学杂志(英文版)

<p><b>PURPOSE</b>To evaluate and compare the effects of heart rate on conduction velocity in the cavotricuspid isthmus (CTI) and septum in patients with and without typical atrial flutter (AF) using electro-anatomic mapping (EAM) of the right atrium (RA).</p><p><b>METHODS</b>Ten patients (age 53+/-10 yrs, 7M/3F) with AF and 13 patients (age 51+/-11 yrs, 5M/8F) with atrioventricular nodal reentrant tachycardia (AVNRT) underwent conventional electrophysiological study, electro-anatomic mapping and radiofrequency ablation. Using EAMs obtained during coronary sinus pacing at pacing cycle length (PCL) 600 ms, 400 ms, and 300 ms, we evaluated conduction velocities in the CTI and septum of RA in 10 patients with AF and compared EAMs to 13 patients with AVNRT to determine whether the conduction slowing required to maintain AFL was related to changes in volume alone or altered RA electrophysiology.</p><p><b>RESULTS</b>Conduction velocities in CTI and septum were significantly slower at all PCL when AF was compared to AVNRT (*P<0.05). Additionally, in the AF group, septal conduction velocities were slower at PCL 600 ms and 400 ms, but not at 300 ms compared to CTI (*P<0.05). In AF, during PCL 300, conduction in CTI slowed significantly compared to PCL 600 and 400 ms such that there was no difference between CTI and septum at PCL 300.</p><p><b>CONCLUSIONS</b>There is slower conduction in the septum compared to the CTI in all patients. However, in patients with AF, there is significant slowing of conduction in the CTI and septum as well as decremental rate-dependent slowing of conduction in the CTI. These findings indicate that in addition to RA enlargement, changes in atrial electrophysiology distinguish AF patients from patients with AVNRT.</p>

Electro-anatomic mapping of the right atrium: anatomic abnormality is an important substrate / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To map and compare the right atrium in patients with AF to those with atrioventricular nodal reentrant tachycardias (AVNRT, as control group) and to investigate the anatomical and electrophysiological abnormality of the right atrium in AF.</p><p><b>METHODS</b>The anatomy and electrophysiology of right atrium and cavotricuspid isthmus were evaluated in 20 patients with AF (16 M/4 F, mean age 55.9 +/- 10.68 years) and 26 patients with AVNRT (9 M/17 F, mean age 47.50 +/- 19.56 years) during coronary sinus pacing at 600 ms prior to ablation with electro-anatomical mapping system. Right atrial volume (RAV), the length and width of cavotricuspid isthmus (IsL, IsW), unipolar and bipolar voltage in the right atrium (UniV-RA, BiV-RA) were measured and compared between patients with AF and those with AVNRT.</p><p><b>RESULTS</b>RAV, IsL, IsW, UniV-RA, and BiV-RA were 143.22 +/- 40.72 vs 104.35 +/- 21.06 ml, 39.31 +/- 8.10 vs 32.42 +/- 9.77 mm, 30.54 +/- 7.48 vs 23.15 +/- 6.61 mm, 1.96 +/- 1.24 vs 1.53 +/- 0.91 mv and 1.47 +/- 1.47 vs 1.29 +/- 1.12 mv in AF and AVNRT respectively.</p><p><b>CONCLUSION</b>The right atrial volume is larger; both the length and width of cavotricuspid isthmus are greater. Unipolar and bipolar voltages in the right atrium are higher in AF than in AVNRT, suggesting that the enlarged right atrium, increased length and width of cavotricuspid isthmus, and concomitant atrial hypertrophy are important substrates for initiation and perpetuation of typical AF.</p>