Changes in left atrial size and function early after cardiac resynchronization therapy as assessed by conventional two-dimensional echocardiography.

AIMS: Cardiac resynchronization therapy (CRT) was shown to improve left atrial (LA) size and function within months after the procedure. We aimed to assess the impact of CRT on left atrial (LA) size and function within days after the procedure. Materials and methods: Twenty-eight consecutive patients with CRT were evaluated before the procedure and within 3 days afterwards, and 25 of them were also examined at three months. Echocardiography was performed to assess LA size and function: LA volumes indexed to body surface (LAVIs) were measured at different moments during the cardiac cycle: ventricular end-systole - maximum LAVI (LAVImax), before atrial systole (LAVIpreA), and at ventricular end-diastole - minimum LAVI (LAVImin). These measurements were further used to calculate LA function parameters: LA total emptying fraction, activeemptying fraction and passive emptying fraction. RESULTS: LAVImax decreased within days after the procedure - 45.5 mL/ m2 (38.2-56.7) vs. 42.9 mL/m2 (32.1- 56.2), p <0.05, as did LAVImin - 27.1 mL/m2 (22.9-41.9) vs. 25.9 mL/m2 (17.8-38.1), p <0.05, and LAVIpreA - 40.0 mL/m2 (31.3-53.0) vs. 35.5 mL/m2 (25.8-49.1), without significant changes in functional parameters. All LAVIs were correlated to the diastolic filling time/RR interval ratio after CRT, but not before. CONCLUSIONS: LAVIs may be reduced within days after the implant procedure in responders to CRT, while atrial functional parameters remain unchanged. Correlations beween LAVIs and the diastolic filling time/RR interval ratio after CRT suggest that early optimization of atrio-ventricular and ventriculo-ventricular delays may have a positive and immediate impact on LA size.

Transcranial measurement of cerebral microembolic signals during pulmonary vein isolation: a comparison of two ablation techniques.

BACKGROUND: Pulmonary vein isolation has increasingly been used to cure atrial fibrillation, but concerns have recently been raised that subclinical brain damage may occur because of microembolization during these procedures. We compared the occurrence of bubble formation seen on intracardiac echocardiography and the microembolic signals (MESs) detected by transcranial Doppler on the use of different ablation techniques and anticoagulation strategies. METHODS AND RESULTS: This prospective study included 35 procedures in 34 consecutive patients (age, 52; SD, 12.8 years; female:male 9:25). Pulmonary vein isolation was performed with a cryoballoon and the conventional anticoagulation protocol (activated clotting time >250 s) in 10 procedures (group 1), with a multipolar duty-cycled radiofrequency pulmonary group 2), and with regime a pulmonary vein ablation catheter with an aggressive anticoagulation (activated clotting time >320 s) in 13 procedures (group 3). The mean total numbers of MESs detected during the procedures were 833.7 (SD, 727.4) in group 1, 3142.6 (SD, 1736.4) in group 2, and 2204.6 (SD, 1078.1) in group 3 (P=0.0005). MESs were detected mostly during energy delivery in the pulmonary vein ablation catheter groups, whereas a relatively even distribution of emboli formation was seen during cryoballoon ablations. A significant correlation was found in all groups between the degree of bubble formation on intracardiac echocardiography and the number of MESs (P=0.0000). CONCLUSIONS: Duty-cycled radiofrequency ablation is associated with significantly more MESs, even when more aggressive anticoagulation is applied. With both techniques most of these microemboli are gaseous in nature.

Adenosine-dependent concealed accessory pathway.

Adenosine is routinely used during ventricular pacing to exclude the persistence of retrograde accessory pathways conduction after radiofrequency (RF) ablation procedures by blocking conduction over the atrioventricular node. This is the first report of an adenosine-dependent concealed accessory pathway demonstrating transient conduction only after adenosine administration. Our findings may have potential clinical implications in reducing recurrence after accessory pathway ablation. Furthermore, it may add relevant information regarding the ability of adenosine to elicit dormant conduction after RF ablation, a phenomenon that has acquired considerable interest in the era of pulmonary vein isolation.