Detection of delayed ventricular activation on the body surface in XXXX .

@entity235 @entity63
This study describes a noninvasive method for detecting delayed ventricular activation, caused by @entity63 , on the body surface. Signal averaging and a newly developed high-pass digital filter were used. The filter has the property that it does not create an artifact or ring after the QRS complex ends, thereby allowing the detection of microvolt-level potentials that occur immediately after the QRS complex. Eleven @entity235 were studied before and during acute @entity63 induced by coronary artery ligation and latex embolization. The @entity63 region was mapped with bipolar electrodes and, after the chest was rapidly closed, signal-averaged recordings were made from the body surface. Repeated cycles of ventricular mapping and signal averaging were performed. In each @entity235 , delayed and fractionated electrograms were recorded directly from the @entity63 epicardium that lasted a maximum of 118 +/- 18 ms after QRS onset. The duration of the ventricular electrograms varied with time. Whenever delayed epicardial electrograms were recorded, filtered signal-averaged leads showed microvolt-level potentials early in the S-T segment that were continuous with the QRS complex. The duration of ventricular activation, as measured from the bipolar electrograms and from the filtered signal-averaged leads, correlated well (r = 0.93, P less than 0.001). Because of the absence of filter ringing, low-level potentials could be detected less than 40 ms after the QRS complex ended. This study demonstrates that microvolt-level potentials arising from delayed ventricular activation can be reliably detected on the body surface, even when they occur just after the QRS complex.
