Internal atrial shock delivery by standard diagnostic electrophysiology catheters in goats: effects on atrial electrogram amplitude and tissue architecture.

AIMS: In this study, we evaluated the effects of atrial shock delivered via diagnostic electrophysiology catheters. METHODS AND RESULTS: In 11 anaesthetized goats, decapolar catheters were positioned in the right atrial appendage (RAA) and coronary sinus (CS). Three different catheters and two cardioversion protocols were evaluated. In four goats, 50 J shocks were delivered using catheters with 1 mm electrodes (surface area 70 mm(2)). In 6 goats, catheters with 2 mm electrodes (area 140 mm(2)) were used. In three of the six goats, 50 J shocks were given while in the other 3, 10 J shocks were delivered. In 1 goat 50 J shocks were delivered via 5 mm electrode catheters (area 310 mm(2)). No persisting adverse effects occurred. However, the electrogram amplitude at the RAA and CS decreased by >50-98% (P > 0.01). The amount of amplitude decrease was most pronounced at the CS site and for 50 J shocks. Goats were sacrificed after 9 +/- 1 days. Macroscopy revealed endocardial lesions at the electrode locations. Microscopy showed endocardial thrombosis, and necrosis with formation of granulation tissue. Changes were most marked with diagnostic catheters and 50 J shocks. CONCLUSIONS: Atrial shock delivery via diagnostic catheters causes local ablation lesions. The amount of amplitude decrease, macroscopic and microscopic damages were related to the energy applied and electrode surface area.