PULSATILE BLOOD FLOW 



857 



rO 



-100 



-200 



IT 



IA 



■ ■ I — 

 1.0 



SECONDS 



20 



90 



■70 



L 50 



30 



fig. 25. The effect of natural 

 breathing on flow in the thoracic 

 and abdominal vena cava of the 

 dog (closed chest). Tracings 

 represent from above downward. 

 AO = the aortic pressure in mm 

 Hg; IT = intrathoracic pressure 

 in mm H 2 0; VC-\ = thoracic 

 inferior vena caval blood flow in 

 ml/sec; VC-i = flow in IVC 

 below renal veins in ml/sec; 

 RA = right atrial pressure in 

 mm H 2 0; FV = femoral vein 

 pressure in mm H 2 0;and IA = 

 intra-abdominal pressure in mm 

 H,0. [After Mixter (28).] 



PULMONARY BLOOD FLOW 



AORTIC BLOOD FLOW 



-i ■■■>■ AfttfH 



fig. 26. Left and right ventricular 

 ejection pulses in congenital atrial 

 septal defect before and after repair 

 (7 -year-old boy). Repair consisted of 

 an open-heart procedure using total 

 cardiopulmonary bypass while closing 

 the defect by means of a suture tech- 

 nique. Figures between the flow pulse 

 tracings represent the mean output of 

 the ventricles averaged over several 

 heart cycles. The contour of the trac- 

 ings is typical of normal tracings found 

 in humans and dogs. Stroke volume 

 differs markedly, however, between the 

 two ventricles before and after repair. 

 The repair diminished pulmonary flow 

 and increased the aortic flow. Pre- 

 sumably the difference between the 

 pulmonary and aortic flow after repair 

 results from either /) incomplete 

 closure, or 2) actual difference in the 

 cardiac output between the measure- 

 ments which were not taken simul- 

 taneously. 



to an internal diameter of 3 mm. Blood flow through- 

 out these degrees of experimental coarctation was 

 maintained at the normal level and the stroke flow 

 was maintained primarily by flattening the peak flow 



and broadening of the systolic area. During this time 

 a systolic murmur began softly and increased in 

 loudness and duration; its envelope maintained a 

 contour similar to the contour of the peak of the flow 



