Effects Of L-carnitine On Acute Atrial Electrical Remodeling

Backgroud The pathophysiology underlying electrophysiological remodeling from rapid atrial rates is unknown. Atrial ischemia may play a role in atrial electrical remodeling induced by atrial fibrillation (AF). L-carnitine (LCN) may inhibit the accumulation of long chain acyl carnitine and calcium overloading in the ischemic myocardium. So the effects of LCN on tachycardia-induced acute atrial electrical remodeling and electrophysiological change induced by atrial ischemia were studied. Methods Twenty-four dogs were divided into pace group and ischemia group. Then, each group were randomly divided into normal saline (NS) group and LCN group. In pace group, two 5 F electrode catheters were introduced into the right atrium. Right atrium was paced at 800 bpm for 1 s to induce AF and AF was maintained for 2 h by rapid pacing as soon as sinus rhythm restored. Atrial effective refractory period (AERP), AERP rate adapting feature and right-atrium conduction velocity (CV) before and after 2 h's AF were measured at basic pacing cycle length (BCL) of 200 ms and 150 ms. In pace/LCN group, these parameters were measured again after 24h. In ischemia group, Atrial ischemia was induced by occlusion of an atrial arterial branch that didn't provide blood flow to the ventricles in twelve open-chest dogs. AERP and right-atrium CV were measured at BCL of 300ms, 200 ms and 150 ms before and after 3 h's occlusion of the right coronary artery. The duration of AF induced by programmed pacing were recorded. Histological examination was performed on the pacing sites for ERP measurement.Results (1) In pace/NS group, AERP200 shortened dramatically after 2 h's AF (109±5.5 ms vs. 84.4±4.4 ms, P<0.05). The AERP₂₀₀ show no...