PREEXCITATION The role of initial minimum potentials on body surface maps in predicting the site of accessory pathways in patients with Wolff - Parkinson - White syndrome

Forty-one patients (23 men and 18 women, ages 20 to 66 years) with Wolff-ParkinsonWhite syndrome were studied with isopotential body surface maps during sinus rhythm to find the most reliable index for predicting the sites of single accessory pathways. The sites predicted by surface maps were compared with those confirmed by multicatheter electrophysiologic study or in the course of surgical operation. Location of the initial minimum by a time criterion, 40 msec after onset of the QRS complex, was not reliable enough for prediction in patients with the small delta wave on their electrocardiograms, because ventricular activation via the normal conduction pathway significantly influenced the location of the minimum. Location of the minimum by an amplitude criterion, -0.15 mV or slightly deeper, was influenced minimally by fusion of ventricular activation, the patient's body size, or age and corresponded well to the site of the accessory pathway in 36 of 41 patients. Those minima appeared on circumscribed areas of the map in accordance with the anatomic subdivisions of the atrioventricular ring. Thus location of the minimum by the amplitude criterion was an excellent index for predicting the site of the accessory pathway, regardless of the degree of ventricular fusion. These amplitude-based map features suggest that nonstandard electrocardiograms recorded from selected positions on the body surface can be used as accurate predictors of the sites of accessory pathways. Circulation 74, No. 1, 89-96, 1986. BODY SURFACE MAPPING has recently come into use as a noninvasive diagnostic procedure for locating the site of the accessory pathway in patients with Wolff-Parkinson-White (WPW) syndrome. '4 De Ambroggi et al.2 and Iwa et al.3 reported the location of maxima and minima during the first 20 to 40 msec of the QRS complex to be a useful index. Significant fusion of the ventricular activation fronts, both from the normal conduction system and the accessory pathway, is known to affect potential distribution during the QRS complex and to complicate the interpretation of location of the pathway.46 Benson et al.4 concluded that the potential distribution From the Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Osaka, and the Department of Public Health, Niigata University Medical School, Niigata, Japan. Address for correspondence: Shiro Kamakura, M.D., Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1, Fujishiro-dai, Suita, Osaka 565, Japan. Received June 11, 1985; revision accepted March 20, 1986. Vol. 74, No. 1, July 1986 at 40 msec of the QRS complex and that of the ST segment could be excellent indexes of the site of pathway only in patients with marked preexcitation during sinus rhythm or in patients with preexcitation maximized by atrial pacing. According to their time-based analytic method, the site could not be predicted accurately without the aid of invasive techniques in many patients with WPW syndrome with the small delta wave. We studied the relationship between the potential distribution on the early QRS surface maps and sites of pathways confirmed at surgical operations or by electrophysiologic studies. This report demonstrates (1) the value of amplitude-based map analysis over the time-based analysis in predicting the site of single accessory pathways, independently of the presence of ventricular fusion, and (2) the exact locations of the initial minima on a clearly defined electrode grid, which may improve the diagnostic utility of standard or nonstandard electrocardiograms (ECGs). 89 by gest on A ril 1, 2017 http://ciajournals.org/ D ow nladed from