Noninvasive recording of His-Purkinje activity in patients with complete atrioventricular block. Clinical application of an "automated discrimination circuit".

Abstract

In seven patients with complete atrioventricular (AV) block, His bundle electrograms (HBEs), standard ECG recordings, bipolar esophageal ECGs and highly amplified, filtered, bipolar chest lead ECGs were simultaneously recorded. The filtered chest lead ECG was averaged to determine His-Purkinje activity (HPA). A simplified device, the "automated discrimination circuit," was used to selectively eliminate the superimposed atrial and ventricular potentials that are characteristic of complete AV block and unsuitable for signal averaging. The processed chest lead ECG was amenable to conventional techniques of signal averaging. In four patients with block proximal to the AV node diagnosed by HBE, there was no activity after the P wave in the surface-averaged ECGs. HPA was consistently recorded before the QRS in the surface-averaged ECG. The measurements of the HV and HPA-V intervals were very close, with a difference of less than 2 msec. Three patients with block distal to the His bundle by HBE showed a loss of electrical potential before the QRS in the surface-averaged ECG, but had a consistent HPA after the P waves. The P-HPA intervals coincided well with PH intervals, with a maximal difference of 5 msec.

Magnetocardiograms in Clinical Medicine: Unique Information on Cardiac Ischemia, Arrhythmias, and Fetal Diagnosis

“…11B). A statistically significant relation between His-ventricular intervals measured on the body surface and those determined in an EP study has not been demonstrated in previous reports (59)(60)(61)(62)(63) …”

Noninvasive Recording of His Potential Using Magnetocardiograms

“…Noninvasive techniques are more ideal and practical than invasive ones and therefore it is advantageous if the His However, the noninvasive recording of the His potential is somewhat controversial because of the need to differentiate 'noise' from physiological signals originating from the heart. Several methods, such as using signal averaging, 5,6 lead positions, filters, 7 type of calculation and a magnetically shielded room, 8 have been reported for ECG. Signal averaging limits the clinical indication for recording the His potential to patients with regular HV conduction because signal averaging and specific filtering may distort physiological signals.…”

“…Statistical significant correlation between the HV intervals recorded on the body surface and those from an EPS has not been previously demonstrated. [6][7][8]10 …”

The applicability of the signal averaging technique in clinical cardiology

“…Following these earlier studies, three independent groups, Berbari et al (1973), Flowers et al (1973);and Stopczyk et al (1973) reported their initial experiences on surface His bundle recordings by signal averaging. Since that time numerous investigators have applied this technique to obtain noninvasive His bundle potentials from the body surface (Furness et al, 1975;Hishimoto and Sawayama, 1975;Honda et al, 1977;McKenna et al, 1979;Pernod et al, 1977; al., 1975;Takeda et al, 1979;Van den Akker et al, 1976;Vincent et al, 1978Vincent et al, , 1980Wajszczuk et al, 1978). In contrast to these discontinuous registrations by sampling and averaging hundreds of cardiac cycles, Trethewie (1975) tried to receive surface His bundle potentials from his leads A, B, and C by proper filtering and lowlevel amplifying . In 1977 we could demonstrate that during simultaneous registrations of intracardiac and surface His bundle potentials obtained by Trethewie's method, the surface His bundle signals corresponded to the intracardiac ones in about 60% of cases (Hombach et al, 1977b).…”