Analysis of 174 ventricular premature beats, 172 retrograde P waves and 36 ventricular echoes with reference to atrial echoes through the S-A node.

Abstract

Electrocardiograms were taken from a 36-year-old female with vegetative neurosis to obtain 174 ventricular premature beats, 172 retrograde P waves, 36 ventricular echoes and 8 atrial echoes through the S-A node or by way of the S-A junctional region. The atrial echo through the S-A node were differentiated only in esoplrageal leads which showed 4 types of P waves; a sinus P wave, a retrograde (nodal) P wave, a retrograde P wave followed by a ventricular echo and an antegrade P wave of an atrial echo. 1. An R-R' interval (an interval between the sinus-conducted beat and the ventricular premature beat) of 0.40 to 0.48 second was observed in 100 per cent of ventricular premature beats with ventricular echoes and in 81 per cent of those without them. 2. An R'-P' interval (an interval between the ventricular premature beat and the following retrograde P wave) of 0.24 to 0.31 second was observed in 78 per cent of ventricular premature beats with ventricular echoes. While, an R'-P' interval of 0.16 to 0.23 second was observed in 79 per cent of ventricular premature beats with-out ventricular echoes. 3. The R-R' interval was inversely proportional to the R'-P' interval. The ventricular echo occur-red when the R-R' interval was less than 0.48 second and the R'-P' interval greater than 0.22 second. 4. When the R-R'-R' interval (an interval between the sinus-conducted beat preceding the ventricular premature beat and the ventricular echo response) was the same, a shorter R-R' interval was associated with a longer R'-P' interval and a shorter P'-R' interval (an interval between the retrograde P wave and the ventricular echo response). While, a longer R-R' interval was associated with a shorter R'-P' interval and a longer P'-R' interval. 5. When the R-R' interval was the same, a longer R'-P' interval was ordinarily preceded by a longer R'p-R interval (an interval between the preceding ventricular premature beat and the following sinus-conducted beat) and followed by a ventricular echo. When the R-R' interval was preceded by a shorter Rp-R interval (an interval between the preceding sinus-conducted beat and the sinus-conducted beat followed by R'), it was followed by a shorter R'-P' interval and not followed by a ventricular echo. 6. An effort was made to explain ventricular echoes in terms of re-entry by retrograde stimulation. The ectopic focus in the A-V junctional region may be discharged by a retrograde impulse and made fire again antegrade in the same way as in the premature beats. 7. In esophageal leads, when the ventricular premature beat was neither interpolated nor followed by a fully compensatory pause, the following P wave showed aberrant intra-atrial conduction. The temporal relation between the regular sinus impulse and this aberrant P wave seemed to indicate that the preceding sinus impulse was blocked by retrograde propagation of the ventricular premature impulse, that the succeeding sinus impulse was abolished by pre-mature firing of the S-A node by re-entry of this retrograde impulse and that a slower conduction in the S-A node afforded incomplete recovery to the atria and enabled aberrant re-excitation of the atria.