STENOSIS AND INSUFFICIENCY 66 I 



FLOW 

 L/Min 



Cm HjO 







A P 100 



MM HG 50 







MW ^ 



KGM 







100 



so 

 TPR 60 



40 



20 







AUMl 



_L 



400 



TPR 

 300 



200 



100 







Fio. 5. Hemodynamic effects of 

 superimposing mitral regurgitation on 

 aortic regurgitation, NL, no lesion, AI, 

 aortic regurgitation; AI + MI, after 

 mitral regurgitation was superimposed; 

 T, sum of effective and aortic regurgi- 

 tant flows. R, aortic regurgitant flow; 

 E, effectise flow in liters /min; LIED, 

 left ventricular end-diastolic pressure; 

 LA, mean left atrial pressure; AP, 

 aortic pressure; MW, effective minute 

 work in kilogram meters; TPR, calcu 

 lated total peripheral resistance; HR, 

 constant heart rate 133/min. Dog 

 weight, 25.0 kg. [From Welch et al. 

 (197).] 



HR --I33 



ventricular filling pressure was associated with a siz- 

 able stroke work increase in the normal, no change 

 was found in aortic regurgitation despite markedly 

 elevated filling pressures. Regan and associates sug- 

 gest that the twofold load on the left ventricular 

 myocardium, with both increased aortic pressure, 

 against which the contraction has to occur, and in- 

 creased venous inflow in the presence of latent myo- 

 cardial failure caused the ventricular failure to be 

 manifested. This development could be prevented 

 when the venous inflow was restricted by leg tourni- 

 quets. 



The findings of Sancetta & Kleinerman (174), who 

 studied patients with aortic valvular lesions at rest 

 and during light exercise, agree with this conclusion. 

 In those patients who had not been in failure and 



who had normal pulmonary pressures at rest, the 

 increased venous inflow during exercise (if it was not 

 combined with increased resistance to left ventricular 

 outflow) did not give rise to any hemodynamic signs 

 of ventricular failure. This was in contrast to those 

 patients who had elevated pulmonary pressure at 

 rest, and whose left ventricular myocardium already 

 was consequently under strain. These latter patients 

 had further increase in left ventricular filling pressure 

 with inadequate total blood flow even in mild exercise. 

 Similar findings have been reported by Gorlin and 

 co-workers (88, 89), who studied fi\-e patients with 

 aortic incompetence and found the left atrial pressure 

 elevated at rest in one and normal in four; and efTec- 

 tive cardiac output normal in four and low in one. 

 On exercise, the left atrial pressure increased in all. 



