102 PULSE RECORDS IN THEIR RELATION TO 



Whatever the ultimate factors involved, the practical outcome 

 remains unaffected. The " c " wave in the jugular may be safely 

 taken for clinical purposes as synchronous with the primary wave of 

 the arterial pulse in the neck at the same point, and it thus forms a 

 valuable standard in the interpretation of tracings. 1 



(c) The Third Positive or " v " Wave. The chief difficulty 

 in interpreting the third positive or " v " wave lies in the dif- 

 ference of opinion in regard to its instant of onset. The ex- 

 planation of its occurrence, as given by any particular author, 

 depends upon the time relations which he accepts for its various 

 phases. Thus, those who believe in its cnset during systole 

 of the ventricle, consider that the venous flow which fills the 

 auricle during this phase is an important contributory cause 

 (Potain, Porter, Gottwalt, Mackenzie, Morrow, Hering). Those 

 who regard it as arising with the commencement of ventricular 

 diastole, attribute it to an elevation of the auriculo- ventricular 

 ring (Porter, 2 Gerhardt). A similar view is held by Wenchebach. 

 It has also been attributed in part to dicrotic rebound at aorta 

 and pulmonary orifices (Riegel 3 ) ; and to tricuspid regurgitation 4 

 (Mackenzie). 



For our present purposes it will be convenient to regard the 

 onset of the " v " wave as inconstant in position, and to briefly 

 discuss those factors held to take part in the production of the 

 wave, either in that portion of it which is said to occur before, 



1 The second positive wave was estimated by Porter as representing an auricular 

 pressure of 5 mm. Hg. 



2 Porter recognised it as a contributory cause. 



8 Cp. criticisms of Gerhardt and remarks by Hering ( y3c ).- 



4 The difficulties of this question are very great. That the wave is enhanced 

 when there are evidences of tricuspid regurgitation is generally admitted. The 

 opinion rests chiefly on the proposition that tricuspid reflux may be a nonnal 

 event. Such a reflux is not admitted by physiologists, but is strongly held 

 by the northern schools of clinical medicine. The evidence cited is the 

 presence of a systolic murmur, regarded as an indication of tricuspid insufficiency. 

 \Vhether those presenting such a murmur, a sound which is said to be of common 

 occurrence, are to be recognised as falling within the category of normal subjects, 

 is a question outside the bounds of this article. Full references and many inter- 

 esting observations may be found in the writings of Gibson ( l7 ) and in the first 

 articles of Mackenzie. Our ignorance of the conditions under which tricuspid 

 leakage may occur in its earlier stages appears to be very great, and little or no 

 experimental work has been done on the subject. Statements attributing to 

 Gibson the view that regurgitation is a factor in the production of the "v" wave 

 are without foundation. 



