Electrical Axis of the Human Heart. 



65 



Transverse... 

 Eight lateral 

 Axial 



0-0020 volt. 

 0-0024 „ 



Left lateral 

 Equatorial . 



0-0002 „ 



0-0028 

 0-0015 

 0-0012 



Inferior transverse 



Pathological Applications. 



The various applications of the electro-cardiogram to clinical diagnosis of 

 heart lesions fall into two chief divisions : Class A, in which the indications 

 are certain ; Class B, in which they are uncertain. Class A is represented by 

 the arhythmire ; no mistake is possible e.g. as to alterations of frequency and 

 rhythm, coupled beats, auriculo-ventricular dissociation. Class B includes 

 among many others the supposed electrical signs of right and left ventricular 

 hypertrophy and of partial interruptions of auriculo-ventricular conduction. 

 It is as regards Class B that I believe it to be most necessary to pay attention 

 to the physical relations of the normal heart. 



The electrical signs that are accepted by clinical authorities as associated 

 with right ventricular hypertrophy as expressed in clinical language are 

 " small E p large B m ," or, as I prefer to express it, small transverse, large 

 left lateral spike. These are, as has been explained above, physical evidence 

 of an approximately vertical electrical axis. The great majority of clinical 

 observers agree in stating that this combination of small E T and large E ni 

 is common in mitral disease, and that it signifies hypertrophy of the right 

 side of the heart. I have seen many cases during the last three years that 

 are in agreement with this statement, but, on the other hand, I have during 

 the last 20 years met with still more numerous cases of apparently perfectly 

 normal persons that presented this combination, and have, only inferred that 

 they possessed vertical hearts. I have become accustomed to expect to find 

 this combination in infants and in any tall healthy young man accustomed to 

 take plenty of open-air exercise. Therefore, without presuming to express any 

 opinion as to the clinical value of this sign of right ventricular hypertrophy, 

 I do venture to say that in the first instance our reasoning from the sign should 

 be limited to the conclusion that in its presence the electrical axis of the 

 heart must be vertical or directed to the right, and bear in mind that this 

 indication is presented by the hearts of many normal persons. The diagnosis 

 of right ventricular hypertrophy has to be established on independent clinical 

 grounds. 



The electrical signs that are presented as being significant of left 

 ventricular hypertrophy are, in clinical language, large E p small or reversed 



VOL. LXXXVIII. — B. F 



