Stimulation of the intrinsic cardiac autonomic nervous system results in a gradient of fibrillatory cycle length shortening across the atria during atrial fibrillation in humans.

INTRODUCTION: The intrinsic cardiac autonomic nervous system (ANS) is implicated in atrial fibrillation (AF) but little is known about its role in maintenance of the electrophysiological substrate during AF in humans. We hypothesized that ANS activation by high-frequency stimulation (HFS) of ganglionated plexi (GP) increases dispersion of atrial AF cycle lengths (AFCLs) via a parasympathetic effect. METHODS AND RESULTS: During AF in 25 patients, HFS was delivered to presumed GP sites to provoke a bradycardic vagal response and AFCL was continuously monitored from catheters placed in the pulmonary vein (PV), coronary sinus (CS), and high right atrium (HRA). A total of 163 vagal responses were identified from 271 HFS episodes. With a vagal response, the greatest reduction in AFCL was seen in the PV adjacent to the site of HFS (16% reduction, 166 ± 28 to 139 ± 26 ms, P < 0.0001) followed by the PV-atrial junction (9% reduction, 173 ± 21 to 158 ± 20 ms, P < 0.0001), followed by the rest of the atrium (3-7% reduction recorded in HRA and CS). Without a vagal response, AFCL changes were not observed. In 10 patients, atropine was administered in between HFS episodes. Before atropine administration, HFS led to a vagal response and a reduction in PV AFCL (164 ± 28 to 147 ± 26 ms, P < 0.0001). Following atropine, HFS at the same GP sites no longer provoked a vagal response, and the PV AFCL remained unchanged (164 ± 30 to 166 ± 33 ms, P = 0.34). CONCLUSIONS: Activation of the parasympathetic component of the cardiac ANS may cause heterogenous changes in atrial AFCL that might promote PV drivers.

Robotic catheter ablation of ventricular tachycardia in a patient with congenital heart disease and Rastelli repair.

Robotically assisted catheter ablation has been proven feasible in patients with a variety of atrial arrhythmias. The potential to provide improved catheter tip maneuvering and stability potentially makes it ideal for complex ablation procedures. We present the case of a patient with complex congenital heart disease with previous Rastelli repair and recurrent ventricular tachycardia (VT) who underwent robotically assisted mapping and ablation for right ventricular VT, utilizing substrate mapping techniques.

Intra-coronary guidewire mapping-a novel technique to guide ablation of human ventricular tachycardia.

HYPOTHESIS: Endocardial catheter ablation of ventricular tachycardia (VT) may fail if originating from epicardial or intramural locations. We hypothesized that mapping could be achieved using an angioplasty guidewire in the coronary circulation, to guide trans-coronary ablation. METHODS AND RESULTS: Six patients (2 male), 64 +/- 14 years and previously unsuccessful endocardial VT ablation were studied. Using ECG and existing endocardial mapping data, a coronary artery supplying the predicted VT origin was selected. A 0.014-in angioplasty guidewire was advanced into branches of the artery and connected to an amplifier to record unipolar signals against an indifferent electrode within the inferior vena cava. An uninflated angioplasty balloon was advanced over the wire such that only the distal 5 mm was used for mapping. One VT per patient was mapped (CL 348 +/- 102.1 ms). Diastolic potentials were recorded from all (77.7 +/- 43.8 ms pre-QRS onset) and concealed entrainment demonstrated in 3. Pacemapping during sinus rhythm was used in the remainder due to failure of entrainment (n = 2) or degeneration to VF (n = 1). Following branch identification, cold saline injection causing VT termination was used for further confirmation. Five VTs were ablated using intra-coronary ethanol injection via the central lumen of the inflated over the wire balloon. The other was ablated using radiofrequency energy in a coronary vein adjacent to the target artery, which was too small for an angioplasty balloon. No complications or recurrence of ablated VT was seen over 19 +/- 17 months of follow up. CONCLUSIONS: Intracoronary guidewire mapping is a novel method of electrophysiological epicardial mapping to help guide trans-coronary VT ablation.