[Electrophysiologic characteristics of multiple atrioventricular accessory pathways in patients with pre-excitation syndrome].

The electrophysiologic studies in 4 patients with multiple accessory pathways (AP) were reported. The results showed that in these patients, the electrophysiologic characteristics were diversified: The VA intervals often changed abruptly during ventricular pacing at a set rate; and during ventricular pacing with incremental rate or a single premature stimulus scanning, the VA intervals revealed several different constant values. At the onset of AV reentrant SVT with wide QRS complex, the HBE showed VA-VA sequence and no H wave could be found; when orthodromic reentrant SVT, the VA interval and SVT cycle length were various, especially at the beginning of the onset. It was found that when the multiple APs located at both the right and left side and the septum of the heart, the variation of the VA interval would follow the variation of the atrial excitation sequence; when the multiple APs located at the same side of the heart, the atrial excitation sequence was unchanged. Of the 4 cases, 3 received epicardial mapping and surgical treatment. All the existence and locations of the APs suggested by the electrophysiologic studies were confirmed during the operation except one AP in which the location was slightly deviated from the pre-estimation.