58 



Scientific Proceedings (79). 



branch block may be instances of only partial blocks or rather of 

 lesions beyond in the arborizations. Our gross pathological 

 specimens tend to support this view. 



The criteria in the electrocardiograms which we have used are 

 in general as follows: 



1. Abnormal prolongation of the time interval of the QRS 

 group beyond the normal limit of 0.1 second. This prolongation 

 is most manifest in a widening of the R wave, so that its foot 

 pieces are abnormally separated. The R wave no longer has its 

 slender, tall, spike-like appearance, but is broader and sometimes 

 blunter than normally. 



2. Notching of the R wave. This notching may appear on the 

 ascending or descending limb, on both limbs, or at the peak. It 

 may be multiple, and its degree and location may vary slightly 

 from beat to beat. In arrhythmias, the shorter the preceding 

 inter- ventricular interval, the more pronounced the evidence of 

 disturbed intra-ventricular conduction. 



3. Low voltage as expressed by a low amplitude of the waves 

 in all three leads. This change is not uniformly present, but when 

 it occurs it helps to differentiate this type from the electrocardio- 

 grams typical of bundle branch block. 



4. Absence of the typical diphasic curves with huge T' waves 

 found in experimental bundle branch block. 



We have obtained records of 17 such cases which presented the 

 clinical pictures of arteriosclerosis, coronary artery disease, angina 

 pectoris, cardio-vascular-renal disease, syphilis, myocardial dis- 

 ease, some associated with auricular fibrillation or flutter, and we 

 have learned that the prognosis of these cases is serious — probably 

 graver than that of those individuals who present records typical 

 of block of the right or left chief branches of the bundle of His. 



Pathology. — In but five of the cases have we had an oppor- 

 tunity to examine the hearts pathologically; in a sixth case we 

 secured only the septum including the atrioventricular bundle. 

 Serial sections are being prepared. 



1. At the present time we can report that four of the cases 

 showed coronary artery sclerosis with closure of the anterior 

 descending branch of the left coronary artery. This artery gives 

 off septal branches which supply the anterior part of the septum. 



