PHYSIOLOGIC CONSEqUENCES OF CONGENITAL HEART DISEASE 



441 



TABLE 4. Average* Inlra-Arterial Pressures {mm of Mercury) and Arterial-Pulse Propagation Times in 

 Normal Subjects and in Patients With Coarctation of the Aorta\ 



Normal subjects (4), aged 

 19-34 



Patients (21) with coarc- 

 tation of aorta 



Pressure 



Intraradial 



Systolic 



127 

 (109-144) 



196 

 (169^30) 



Diastolic 



65 



(54-85) 



96 

 (76-126) 



Intrafemoral 



Systolic 



126 

 (120-134) 



113 

 (87-133) 



Diastolic 



66 

 (60-69) 



81 

 (63-99) 



Ratio of Femoral to Radial 

 Pressure 



Systolic 



0.96 

 (0.94-0.99) 



0.58 

 (0.43-0.68) 



Diastolic 



0.97 

 (0.91-1 .06) 



0.85 

 (0.67-1 .14) 



Time, sec 



Onset of pulse 



wave, femoral-radial 



difference 



0.00 

 ( — 0.01-0.001 ) 



Onset to peak of 

 femoral pulse 



0.15 

 (0.14-0. 18) 



0.03 0-23 



(—0.01-0.07) I (0.17-0.30) 



Figures in parentheses are extreme values. f Reproduced from Brown el al. (45). 



\'ariation in oxygen satiu'ation of mi.xed \enous 

 blood presumably resulting from a change in cardiac 

 output in the interval between the collection of 

 samples was studied by Barratt-Boyes & Wood (19). 

 In 19 subjects with an average of three samples of 

 blood from the pulmonary artery separated h\ an 

 average interval of 37 (5-147) min, the mean of the 

 maximal \ariation in oxygen saturation was 3.3 per 

 cent and the range was o to 10 per cent. The effects 

 of this normal variation in oxygen saturation can be 

 minimized when comparing the oxygen saturation 

 values of blood from various right heart chambers by 

 rapid consecutive sampling. 



HEMODYNAMIC .-ALTERATIONS .-ASSOCIATED WITH 

 CONGENITAL CARDIOVASCUL.'AR DEFECTS 



Obstruction of Great Vessels 



COARCTATION OF THE AORTA. As early as 1870, 

 abnormalities of the femoral arterial pul.se were 

 observed by Scheele (209) in a patient with coarcta- 

 tion of the aorta, and an elevation of arterial blood 

 pressure in the cephalic portions of the body was noted 

 by Potain (191) in 1892. It was not, however, until 

 the development of suitable apparatus by which 

 precise physiologic investigations might be carried 

 out in intact man that accurate studies of the blood 

 pressure in coarctation have been made. 



Blumgart and associates (35) described the hemo- 

 dynamic findings in two patients with coarctation of 

 the aorta and noted that there was both systolic and 

 diastolic arterial hypertension in the arms of these 

 patients and relativeh' low blood pressure in the legs. 

 Brown and colleagues (45) summarized the hemo- 

 dynamic findings in 21 patients with coarctation of 

 the aorta. Systolic pressure in the radial artery was 



found to be elevated in all patients with coarctation 

 of the aorta (table 4). Radial diastolic pressure, 

 except in one patient, was also elevated above the 

 range of values obtained from normal subjects. In 13 

 of the 21 patients systolic pressure in the femoral 

 artery was below the range of pressures encountered 

 in the normal subjects. However, femoral diastolic 

 pressure, except in two patients, was ele\ated above 

 the normal range. The ratio of femoral to radial 

 systolic pressure averaged 0.58 as compared to the 

 average value of 0.96 obtained in normal subjects. 

 The differences in the ratio of radial to femoral 

 diastolic pressure were less marked, and the ratio fell 

 within the normal range in 5 of the 2 i patients. 



The femoral arterial pulse wave has a characteristic 

 "saw-tooth" contour (fig. 13). This difference in 

 pulse contour from that seen in normal suijjects is 

 produced by propagation of the arterial pulse through 

 the collateral pathways around the coarctation; 

 usually there is relatively little transmission through 

 the coarcted area because of its small diameter (1-2 

 mm). If the interval of time elapsing between occur- 

 rence of the R wave of the electrocardiogram and the 

 onset of the radial and femoral pul.se waves is deter- 

 mined, it is observed that the onsets of the femoral 

 and radial pulse waves occur almost simultaneously 

 in normal .subjects. In patients with coarctation of 

 the aorta, however, the onset of the femoral pulse 

 wave occurs on the average 0.03 sec later than the 

 onset of the radial pulse wave (table 4). The interval 

 of time elapsing between the onset and the peak of 

 the femoral pulse averages 0.15 sec in normal subjects 

 and 0.23 sec in patients with coarctation (table 4). 

 This represents a significant delay in the build-up of 

 the femoral pulse wave in the latter group. 



Fi\e differences have been demonstrated between 

 the cardiovascular dynamics existing in patients with 

 coarctation of the aorta and those in normal subjects. 



