OH. XX.] 



ENDOCARDIAC PRESSURE. 



243 



re-investigated the subject with a more suitable but rather compli- 

 cated apparatus. The principle of the method consisted in placing 

 the cavity of a heart-chamber in communication with a recording 

 apparatus by means of a tube containing saline solution. His 

 recording apparatus consisted of a lever connected to a piston ; 

 the upward and downward movements of the piston-rod were due 

 to the varying pressures exerted on the blood by the contraction 

 and dilatation of the heart ; the rise and fall of the lever were 



Fig. 243. Curve from left ventricle obtained by Rolleston's apparatus ; 

 the abscissa shows atmospheric pressure. 



controlled by the resistance to torsion of a steel ribbon to which 

 it was attached. The above figure (fig. 243) shows the kind of 

 tracing he obtained. He found : 



1. That there is no distinct and separate auricular contraction 

 marked in the curves obtained from either right or left ventricles, 

 the auricular and ventricular rises of pressure being merged into 

 one continuous rise. 



2. That the auriculo-ventricular valves are closed before any 



Fig. z (4- Hiirthle's manometer. 



great rise of pressure within the ventricle above that which 

 results from the auricular systole (a, fig. 243). The closure of 

 the valve occurs probably in the lower third of the rise A B 

 (fig. 243), and does not produce any notch or wave. 



3. That the semilunar valves open at the point in the ventri- 

 cular systole, situated (at c) about or a little above the junction 

 of the middle and upper third of the ascending line (A B), and 

 the closure about or a little before the shoulder (D). 



4. That the minimum pressure in the ventricle may fall below 

 that of the atmosphere, but that the amount varies considerably. 



B 2 



