however, the occurrence of extrasystoles 

 comes in to complicate the arrhythmia and 

 make the pulse irregular. In the jugular trac- 

 ing the height of some or all waves constit- 

 utes a frequent anomaly and is attributa- 

 ble to the fusion of the ventricular wave 

 of one cycle with the a wave of the follow- 

 ing cycle. The number of cardiac pulsations 

 depends on the sinus rate while the pass- 

 age of the contractile waves is taking place 

 and is not influenced by deficiency of con- 

 ductibility. 



In the next later phase of arrhythmia 

 partial heart block appears, indicated at first 

 by the periodic and spaced failure of trans- 

 mission of some of the contractile waves 

 and later by the greater frequency of the 

 interrupted waves with establishment of a 

 relation between the number of auricular 

 and ventricular systoles (usually this relation 

 varies between 3:1 and 2:1). 



The immediate reason for the appear- 

 ance of spaced failures of transmission of 

 the systoles in the cases of increase of the 

 space ac is variable and could only be ap- 

 preciated by an analysis of the tracings. 

 Often those failures indicate exclusively the 

 exhaustion of the conductibility and no other 

 factor is of influence; frequently, however, 

 the gradual delay in the transmission of the 

 systoles, causing the delay of the refractory 

 phase of the ventricle, renders ineffective 

 contractile waves which otherwise would be 

 effective and could complete the cardiac 

 cycle. And still other factors may intervene 

 here. The same reasoning is applicable to 

 the most frequent alternation of the relation 

 of 3:1 to that of 2:1, or vice versa, and 

 only concrete cases lend themselves to ex- 

 planations in this way. 



The last stage of these chronotropic al- 

 terations is that of complete block with a 

 permanent idioventricular rhythm. We alread- 

 y have a large number of cases of this 

 group, all more or less uniform in their clin- 

 ical manifestation and in the course of 

 their symptoms. When one considers the 

 etiologic unity of the syndrome and takes 



into account the short space of time that 

 has sufiiced for us to collect so large a 

 number of observations in a scattered pop- 

 ulation, the high scientific interest of this 

 chapter of cardiac pathology becomes abun- 

 dantly evident. 



The number of radial pulsations in cases 

 of complete block oscillates in the vicinity 

 of thirty and sometimes reaches, but rarely 

 exceeds, forty. We have seen a rate below 

 the first figure in some patients, almost al- 

 ways on taking more or less fatiguing exer- 

 cise. And the progressive diminution of the 

 pulsations to five per minute was observed 

 in one case of death from exhaustion of 

 conductibility. 



In some patients it has been possible to 

 accompany the progressive evolution of 

 the arrhythmia from its commencement, 

 with at first only a delay in the conduction, 

 followed by the periodic and rare failures 

 in the passage of the wave, and then the 

 establishment of a fixed relation between 

 the complete cardiac cycles and the block- 

 ades, and finally the complete block and 

 consequent presence of the true ventricular 

 rhythm. It must be noted that this last con- 

 dition is the mosi persistent and the others 

 represent in this disease only transitory pass 

 ing phases of the ever advancing process. 

 Some of our patients with complete block 

 have survived the arrhythmia for a consider- 

 able period of time; in the majority of 

 them, however, death has occurred as the 

 result of the affection. 



Among the most notable characteristics 

 of the tracings in these cases is the frequent 

 irregularity due to the presence of extrasvs- 

 toles. And, indeed, the heterogenetic pulsa- 

 tions of ventricular origin form a symptom 

 frequently preceding the disturbances of 

 contractibility, which indicates previous 

 changes of the whole muscle or of the prim- 

 itive bundles scattered through it and lo- 

 calized later in the conducting regions. The 

 simultaneous tracings of the jugular pulse, 

 heart beat and radial pulse show here vari- 

 ations, all occurring more or less along the 



