Analysis of PR subintervals in normal subjects and early studies in patients with abnormalities of the conduction system using surface his bundle recordings

Abstract

Utilizing several different approaches to noise reduction, satisfactory beat by beat His bundle activity was recorded from the chest surface in 41 (80%) of 52 normal subjects. Surface atrial to His intervals (PAH) and His to ventricular intervals (HV) were measured in this group and compared with subintervals of the PR segment recorded endocardially from 47 persons with normal electrophysiologic findings. A recent modification in the selection algorithm allows on-line identification of the four of five possible recording sites for utilization in a spatial summation. The ability to record in less favorable circumstances has been improved to the extent that records of suitable clarity for measurement were also obtained in 17 (77%) of 22 individuals with conduction system abnormalities. Comparison of the surface and endocardially acquired data in the normal group reveals no statistically significant difference in the surface acquired PAH and endocardially acquired high right atrial to His (HRAH) intervals, nor in the HV intervals. In a small subset of patients data were acquired by both techniques and no significant differences were found. Thus, when programmed stimulation or endocardial mapping is not required to answer specific clinical questions, in the majority of persons it is possible to record meaningful subintervals from the body surface from each cardiac cycle. Additionally, in instances in which surface P wave activity is obscure in the routine electrocardiogram, this technique enhances atrial electrical activity.

Noninvasive recording of His bundle activity with an analog delay device in normal subjects and patients with atrioventricular block

“…Subsequently, a noninvasive or virtually noninvasive method of recording His bundle activity was developed to overcome the limitations and complications involved in the use of the catheter technique as a routine examination [6]. The previous investigations on the noninvasive recording of His bundle activity were generally performed by the computer average response technique [7,8,[10][11][12][15][16][17][18], or by using exclusive averaging hardware [6,9,13,14,20]. For the averaging method to significantly improve the signal-to-noise ratio, the process of averaging must be driven by the trigger pulse with very accurate timing during the repeated processing.…”

“…Flowers et al [20] recorded ECGs from the endocardium and the body surface in eight patients with conduction system abnormalities and reported that the H-QRS intervals determined in individual patients by the two methods were closer than those in the normal subjects. Out measurements, however, showed that the difference in the H-QRS interval between the noninvasive and invasive recordings was 9 and 12 ms in patients 4 and 6, respectively.…”

“…The noninvasive recording of the His bundle activity was carried out by using a signal averaging technique from a surface standard ECG [7,8]. Many studies of the noninvasive detection of the electrical activity in the region of the His bundle have been performed, in an effort to adapt this method to practical use for clinical recording [9][10][11][12][13][14][15][16][17][18][19][20]. However, the electrical potentials on the surface of the chest wall propagating from the region of the His bundle are very small, in the range of 1-10gV.…”