Author + information
- Received June 13, 1988
- Revision received September 7, 1988
- Accepted September 25, 1988
- Published online February 1, 1989.
- William G. Stevenson, MD, FACC∗,
- James N. Weiss, MD, FACC,
- Isaac Wiener, MD, FACC,
- S.Mitchell Rivitz, MD, FACC,
- Koonlawee Nademanee, MD,
- Thomas Klitzner, MD,
- Lawrence Yeatman, MD,
- Martin Josephson, MD and
- Daniel Wohlgelernter, MD, FACC
- ↵∗Address for reprints: William G. Stevenson. MD, Division of Cardiology, University of California at Los Angeles, CHS 47–123, Los Angeles, California 90024.
Fractionated ventricular electrograms recorded during catheter mapping may arise from areas of asynchronous depolarization associated with slow conduction, the substrate for reentrant ventricular tachycardia, but can also be a nonspecific abnormality or even artifact. To determine whether fractionated sinus rhythm electrograms are associated with slow conduction in humans, the results of endocardial catheter mapping and pacing at 133 endocardial sites in 13 patients were analyzed. Eleven patients had sustained monomorphic ventricular tachycardia and two patients had old myocardial infarction without ventricular tachycardia.
Functional evidence of slow conduction at the recording site was assessed by pacing at that site and measuring the interval between the stimulus artifact (S) and the onset of the QRS complex in the 12 lead electrocardiogram (ECG). During pacing at 89 of 90 sites without fractionated sinus rhythm electrograms, the S-QRS interval was <40 ms, a value consistent with rapid propagation of the stimulated wave front away from the pacing site. During pacing at 21 (49%) of 43 sites with fractionated sinus rhythm electrograms, the S-QRS interval was >40 ms (range 40 to 140), consistent with slow conduction at the pacing site (p < 0.001 versus nonfractionated sites).
In 9 of the 11 patients with ventricular tachycardia analysis of the paced QRS configuration, electrograms during induced ventricular tachycardia or programmed stimulation during tachycardia suggested that a site with a long S-QRS interval during pacing was located at or near a ventricular tachycardia circuit. Therefore, fractionated sinus rhythm electrograms are often associated with slow conduction, which may be the substrate for reentrant ventricular tachycardia. Endocardial pacing at these sites can be used to provide functional evidence of slow conduction in humans.
- Received June 13, 1988.
- Revision received September 7, 1988.
- Accepted September 25, 1988.