( 680 ) 
Physiology. — “ Communications about the electrogram of the atrium 
cordis ” By Dr. A. K. M. Noyons. (Communicated by Prof 
H. Zwaardemaker). 
• (Communicated in the meeting of November 27, 1909). 
Involuntarily the ventricle-image, the tops R and T of which are 
prevailing, has, in the study of the electric phenomena of the heart, 
up till now been the principal subject. The top P by its smaller 
size drew less attention and at the outset was not even observed*! 
At present, however, there are in the literature already some 
data to be found here and there concerning the top P. Thus 
Einthoven j ) has pointed out how with increased action of the heart 
after great physical exertion P may gain in size, how under certain 
definite circumstances P may more or less be split up into a dim 
double-topped image, and besides how under pathological relations^ 
top P may be altered, which is demonstrated by cases of mitral 
stenosis. In this case of disease P would appear longer and enlarged,^ 
which Einthoven thinks may be attributed'to a stronger activity of 
the atrium for the sake of its compensative function. Division of the 
top may also appear. Kraus and Nicolai ’) have corroborated this 
find, just as Samojloff *) and Steshinsky * * * 4 ), who have also been 
able to prove that the phenomenon is not pathognomonic, but de*| 
pends on the relative welfare of the heart in case of mitral stenosis .\ 
According to Vaandrager s ), top P in absolute measure would bei 
higher with the dog than in man. With N. vagi cut through 
Vaandrager found in the dog that P grew three times its height 
and conversely could he make P smaller by stimulating the N. vagi. 
Besides this diminution he got at the same time an alteration in the 
form of top P. 
With moderate bleeding of a sample-animal P increased in size, 
whilst after strong bleeding P grew smaller in the dog. 
Top P was from the outset attributed by Einthoven to the ven¬ 
tricles. 
*) Einthoven : See : Onderzoekingen van het Physiol. Lab. te Leyden. Second 
Series VII and the literature pointed out there. 
-) Kraus F. and Nicolai G. F. Ueber.das Electrocardiogramm unter normalen und 
pathologiscben Verhaltnissen. Berl. klin. Wochenschr. 1907 No. 25 and 26. 
s ) Samojloff A. Electrooardiogramme. Jena 1909. Sammlung anat. und physiol. 
Vorlrage. 
4 ) Samojloff A. und Steshinsky. Ueber die Vorhoferhebung des Elektrokardio- 
gramms bei Milralstenose. Munch, mediz. Wochenschr. No. 38. 1909. 
*) Vaandrager B. Dissertatie Leiden 1908. 
