Physiology. — “On Fibrillation of the Heart’. (First part). By 
Dr. 5. pr Boer. (Communicated by Prof. I. K. A. Wertneim 
SALOMONSON). 
(Communicated at the meeting of March 27, 1920). 
i; 
It had struck me as early as 1914 that a single induction-shock 
applied to the ventricle repeatedly engenders fibrillation of this 
chamber of the heart. [ did not study this phenomenon any further, 
since at that time I was studying the eiectrograms of the extra- 
systoles and of the postcompensatory systoles. 
When, however, I continued my alternation-experiments with the 
bled frog’s heart through extra-stimulation, I noticed the above 
phenomenon so frequently that [ felt called upon to study the rela- 
tions, under which this fibrillation took place, more closely. It now 
appeared that fibrillation of the ventricle occurred after a single 
induction shock only when this was applied directly after the close 
of the refractory stage which always accompanies the systole imme- 
diately preceding. This is clearly illustrated by the curves of fig. 1, 
which were registered') half an hour after the bleeding of a sus- 
pended frog’s heart. In the upper row of curves an induction shock 
was given to the base of the ventricle at 1 a short time after the 
close of the refractory stage. 
Fibrillation of the ventricle was the result which manifested 
itself in the string-curve by totally differing detlections, whose tempo 
was very irregular. Similar results were achieved at 2, 6, and 8. 
We notice that the post-undulatory pause, after fibrillation excited 
in 6, may also be lacking (after 2). After 3 an extra systole is 
interpolated by the extra-stimulus, a phenomenon that may occur 
with a slow heart-beat, as has been first shown by TrenDELENBURG. 
In this case the stimulus was administered at a much later period 
of the ventricle (towards the close of the T-detlection), so that a 
fully co-ordinated extra-systole was the result. In the same way a 
complete extrasystole is generated at 7, because here also the stimulus 
1) In this and the following registrations a non-polarizable electrode was placed 
on the auricles and one on the apex of the ventricle. The tension of the string 
was in all experiments such that 1 mV. yielded a deflection of 1!,. mm. 
