American journal of physiology . ncies in the reports concerningthe beginning of the third general rise in the venous pulse are dueto the fact that the majority ofinvestigators have considered theappearance of the onflow wave asthe beginning of the diastolic rise,and under such circumstances theirthird positive waves (Mackenziesv wave) would, of course, bereported as occurring in differentpositions, changing with the distancefrom the heart and the rapidity ofthe onflow. The Second Onflow Wave. —After the opening of the a-v valvesthe onflow into the ventricle is notquite equal to the degree of
American journal of physiology . ncies in the reports concerningthe beginning of the third general rise in the venous pulse are dueto the fact that the majority ofinvestigators have considered theappearance of the onflow wave asthe beginning of the diastolic rise,and under such circumstances theirthird positive waves (Mackenziesv wave) would, of course, bereported as occurring in differentpositions, changing with the distancefrom the heart and the rapidity ofthe onflow. The Second Onflow Wave. —After the opening of the a-v valvesthe onflow into the ventricle is notquite equal to the degree of relax-ation and the diastoHc fall in pres-sure occurs. Then, as the enlarge-ment of the ventricular cavityreaches its maximum, the onflowvolume can no longer be taken careof, and the increase in pressure, asthe second onflow wave, will appearin the auricle and veins. The beginning of this wave issynchronous with the end of com-plete relaxation of the ventricle,that is, just at the point whenfurther enlargement of the ventricle. l/io SEC. I I I I I L Figure 9. Diagrammatic representation of the e\-ents in the cardiac cycle, in relation tothe normal pulse tracing from the superior vena cava. (1) Curve from the venacava, showing the following variations in pressure: — presystolic rise and fall, sys-tolic rise and fall; first onflow wave, diastolic rise and fall, and the second onflowwave; (2) auricular myogram; (3) ventricular myogram; (4) record of the move-ments of the a-v septum; (5) ventricular volume curve; (6) aortic pressure; (7)intraventricular pressure curve. i8o Ephraim M. Ewing ceases and consequently stops the rapid inflow from the auricleand veins. This is also indicated by the ventricular volumecurves, which show that the inflow of blood is practically com-pleted as the second onflow wave appears, since it is at this pointthat the period of diastasis begins. Hirschfelder (07) and Gibson (07) independently describedthis wave (Hirschfelders ^h and Gibsons b wave),
Size: 1114px × 2243px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookautho, bookcentury1800, bookdecade1890, booksubjectphysiology
