444 



HANDBOOK OF PHYSIOLOGY 



CIRCULATION I 



RIGHT : 



/ ^ 



RADIAL : 



LEFT 

 BRACHIAL 



q: 



W 

 C/5 



LlJ 



q: 



a. 



AORTIC 



RIGHT 

 FEMORAL - 



RIGHT t. 

 DORSALIS 

 PEDIS t 



FIG. 14. Comparison of ccnlial and peripheral arterial pulses (as labeled) from a normal 31 -year- 

 old man. Note gradual increase in time interval between peak of R wave of electrocardiogram and 

 onset of pulse wave and gradual increase in pulse pressure, especially systolic peaks, toward periph- 

 ery. Anacrotic shoulder is present in aortic pulse but barely visible in femoral pulse. There is a 

 secondary wave following primary peak but preceding dicrotic notch in brachial-radial system, and 

 there is absence of this wave in femoral-dorsalis pedis system. The incisiira, sharp and short in aortic 

 pulse, is lost during transmission of pulse wave peripherally. Dicrotic notch, drawn out and deep in 

 brachial-radial system, is practically nonexistent in femoral, and is so drawn out and deep in dor- 

 salis pedis pulse that it approaches end-diastolic pressures. 



immediate postoperative hemodynamic improvement, 

 measurable continued improvement of a lesser degree 

 occurring in succeeding years. Radial and femoral 

 arterial pressures were within the range of normal in 

 the majority ot the patients at the time of the long- 

 term (4-7 years) study, and none had a severe degree 

 of hypertension. 



[ alviilar Deformities H ithout Septal Defects 



AORTIC STENOSIS. As Stated earlier, any of the four 

 intracardiac valves may be congenitally stenotic. A 

 related anomaly of the aortic valve area is subvalvular 

 stenosis. Since the hemodynamic eflfects are closely 

 similar, both lesions are discussed here. Of the two, 

 isolated subvalvular stenosis is more commonly 

 congenital, and isolated valvular stenosis more 

 commonly acquired. 



The cardinal circulatory signs in stenosis of the 

 aortic valve are /) a systolic murmur over the aortic 

 region and large neck arteries, 2) enlargement of the 

 heart to the left, and j) the slow anacrotic ascent of 

 the radial pulse. As long as the ventricles are able to 

 compensate, the minute volume is not decreased, the 



arterial pressures are within normal ranges, and 

 venous and pulmonary congestion is absent. 



It has been found that the aortic opening must be 

 reduced by 60 to 70 per cent of its natural size in 

 experimental animals before the systolic discharge, 

 the blood pressure, or the pulse form is affected (8). 

 Much smaller degrees of stenosis, however, may 

 produce loud .systolic murmurs. Thus loud clinical 

 murmurs, even when associated with demonstrable 

 stenosis on subsequent postmortem examinations, are 

 not necessarily evidence of practically significant 

 hemodynamic impairment of cardiac ejection during 

 hfe. 



U.sually when the left ventricle is compensated, 

 left ventricular diastolic pres.sure is normal while only 

 the systolic pressure is elevated. When aortic stenosis 

 is moderate the pressure gradient between the left 

 ventricle and the aorta is 20 to 50 mm of mercury, 

 and with severe stenosis the gradient is between 50 

 and 100 mm of mercury or more. 



The changes occurring in the aortic pressure curves 

 with aortic stenosis are better understood iiy com- 

 paring them with normal arterial curves. In figure 14 

 pressure pulses recorded simultaneously from different 



