Physiology. — *' On the ventricle-electrogram of the Frogs' 

 heart." By Dr. S. de Boer. (Communicated by Prof. G. van 



RlJNBERK. ^) 



(Communicated in the meeting of October 27, 1917). 



It has appeared from my former investigations that we can admit 

 the width of the R-oscillation of the ventricle-electrogram as a 

 measure for the velocity, with which the impulse is transmitted 

 through the ventricle.') k decrease of the velocity of impulse- 

 transmission is expressed by a widening of the R-oscillation, whilst 

 a narrower R-oscillation betrays an increase of the velocity of 

 impulse-transmission through the ventricle. 



If now we want to trace the influence that the velocity of 

 impulse-transmission has on the shape of the ventricle-electrogram, 

 then we can consequently conclude from the w^dth of the R- 

 oscillation, whether the impulse is transmitted with more or less 

 velocity through the ventricle. Now we can make the velocity 

 of impulse-transmission decrease by exciting an extra-systole of 

 the ventricle at an anticipated moment of the heart-period. If 

 we wish however to compare the electrogram of such an anti- 

 cipated extra-systole of the ventricle with those of the normal 

 periodical systoles of the ventricle, then the requirement must be 

 satisfied, that this anticipated ventricle-systole is brought about by 

 an impulse, that reaches the ventricle along the atrio-venti-lcular 

 systems of connection. The place where the impulse hits the ven- 

 tricle at such an anticipated ventricle-systole must be the same 

 as at the normal periodical ventricle-systoles. Only then we can 

 make a comparison. Otherwise the modification of the shape 

 of the ventricle-electrogram might be attributed to the fact, 

 that the impulse proceeded from another place of the ventricle (e.g. 

 at the surface of the ventricle as at extra-stimulation of this part of 

 the heart). We apply consequently an extrastimnlus to the auricle 

 at an anticipated moment of the heart-period. After the cxtrasy stole 



V These investigations were likewise communicated in the meeting of the 

 Biological section of the Genootschap ter bevordering van Natuur- Genees- en 

 Heelkunde (Physiologendag) held on the SO^h of December 1917. 



») Zeitschrift für Biologie Bd. 65 Seite 128 and Journal of Physiology. Vol 49 

 page 310. 



