80 PULSE RECORDS IN THEIR RELATION TO 



ventricles are expanding and receiving blood from the veins and 

 auricles. The term ventricular diastole is usually loosely applied, 

 and has been avoided in the table ; we have not sufficient knowledge 

 of the period over which the ventricles are expanding actively, if they 

 ever do so, to define the time limits of diastole with precision. 



In referring to the accompanying tables mention must be 

 made of observations recently carried out by Erlanger ( 10 ) and 

 Tigerstedt ( 47 ), the results of which are included. The estimates 

 were made from subjects in whom there were partial defects of 

 the chest wall and in whom the heart was readily accessible. The 

 figures are probably as accurate as any we possess ; Keyt's 

 numbers ( 29 ), dependent on numerous and elaborate measurements, 

 compare well with them. The figures given in the first table are 

 taken as far as possible from young adult subjects, and the delays 

 and velocities exampled in the second table are illustrative of 

 normal pulse rates. Some figures from a tracing after Hiirthle ( 26a ) 

 (Taf. III., Fig. 12) are also given for the comparison of man and 

 the dog. No such estimates are absolute ; there is a wide varia- 

 tion with numerous factors, such as pulse rate and blood pressure. 



But though eventually the cardiographic upstroke is the 

 standard movement on which the chief measurements are based, 

 in clinical practice the frequent absence or inversion of the apex 

 beat renders it unreliable, and it becomes necessary to fix further 

 standards. For this purpose the carotid pulse is chosen as the 

 safest and most useful guide. Its utilisation involves under many 

 circumstances a calculation of the presphygmic interval, and the 

 normal transmission delay of the pulse wave from the semilunar 

 valves to the carotid. In the normal subject the presphygmic 

 interval may show variations of at least '03 sec., with age, pulse, 

 rate, &c. In disease it may amount to as much as '06 sec. In 

 clinical application, in which relatively slow travelling recording 

 surfaces are used, an error of less than '05 sec. is as a rule 

 negligible, and the figure '05 sec. may be taken as a comparatively 

 secure working estimate of the presphygmic interval. The error 

 entailed in calculating the transmission delay from aorta to carotid 

 is probably not greater than '01 sec. in health and '03 sec. in 

 disease ; the interval may be taken for clinical purposes at '03 sec. 1 



1 Weiss and Joachim have recently measured the interval between the first 

 heart sound and carotid pulsation in man (Pfliiger'a Archiv., 1908), and find it as 

 a rule '08 to '09 sec. 



