ABNORMAL LEFT ATRIAL DEPOLARIZATION WAVEFRONTIN PATIENTS WITH PAROXYSMAL ATRIAL FIBRILLATIONASSESSED WITH MAGNETOCARDIOGRAPHY

摘要

Magnetocardiographic moping (MCG) was applied in 23 healthy subjects and in 28 patients with lone paroxysmal atrial fibrillation (AF) initiated by P-on-T atrial premature complexes. Magnetic fields in 33 locations over anterior chest were recorded and averaged. Onset and offset of atrial wave were determined automatically after 40 Hz high-pass filtering. Integral maps were created for the initial part (from onset to 50 ms) and the later part (50 ms backwards from offset) of the unfiltered atrial signals. These integrals coincide with right and left atrial depolarization. Spatial orientation of the magnetic field in frontal plane was analyzed. Duration of filtered atrial wave was 106 +- 9 ms in controls and 109 +- 10 ms in patients (p = n.s.)-^sThe magnetic field orientation during the initial part was on average 28(deg) in controls and 25(deg) in patients (p = n.s.) The orientation during later part was 69(deg) in controls and 142(deg) in patients (p = 0.019), signifying much greater field rotation in patients. Thus MCG mapping reveals altered wavefront direction during late atrial wave but no prolongation in atrial depolarization time in patients prone to lone paroxysmal AF. This suggests that altered conduction to or within the left atrium may underlie tendency to develop atrial fibrillation.