Normal Conduction Intervals and Responses in Sixty-One Patients Using His Bundle Recording and Atrial Pacing

¹ Fellow, Department of Adult Cardiology, Cook County Hospital; Assistant in Medicine, Abraham Lincoln School of Medicine, University of Illinois College of Medicine, Chicago
² Chief, Section of Cardiology and Associate Professor of Medicine, Abraham Lincoln School of Medicine, University of Illinois College of Medicine, Chicago
³ Professor of Medicine, University of Oregon Medical School, University of Oregon, Portland

In the present study, His bundle electrograms (H) were recorded in 61 patients without evidence of conduction disease on the surface electrocardiogram, in order to establish the normal range of conduction intervals. The conduction intervals (in msec) were as follows (mean ± 2 SD): P-H 119 ± 119 ± 38; P-A 27 ± 18; A-H 92 ± 38 and H-V 43 ± 12. Atrial pacing was performed in 45 patients. Thirty patients developed Wenckebach periods proximal to H at a mean rate of 146/min; the others maintained intact A-V conduction up to a maximum paced rate of 160 to 200/min. Sinus node recovery time (SRT) was also measured in 34 of the patients and found to be 988 ± 692 msec (mean ± 2 SD). None of the measurements was significantly different when males were compared to females, or when patients above and below age 45 years were compared. The values reported will be of use in assessing patients with suspected cardiac conduction disease.