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HANDBOOK OF PHYSIOLOGY 



CIRCULATION I 



I Inieclion into dislol pulmonory artery 



|FIG 9 I 



Sampling from ; 

 Systemic artery 



I Injection into distal pulmonary artery 



| fiG 10 I 

 Sampling from ■ 



Systemic artery ( sa i _^ 



10 sec 



IVlQin pulmonary artery ( p/s ) 



I BT , 



L-R 

 0„ 



10 sec 



( BT . Cp)^^ - (BT ■ Cp) 



47 I / ( BT ■ C^ ) 



P SA 



FIG g. Method for localizing small left-to-right shunt by 

 dilution curves recorded from selected sites in right side of heart. 

 Indicator is injected into right or left side of heart downstream 

 to location of left-to-right shunt. In this example, of ventricular 

 septal defect, dye curves virere recorded from systemic artery, 

 right ventricle, and right atrium after injections into branch of 

 pulmonary artery. Note that /) dye was detected in right 

 ventricle before it appeared in systemic artery, thus demon- 

 strating presence of left-to-right shunt, .?) early-appearing dye 

 was not detected from right atrium, localizing site of shunt to 

 right ventricle, and j) dilution curve recorded from systemic 

 artery was not apparently distorted by small (< 20%) shunt 

 that was present. In addition to curves shown, a fourth would 

 be recorded from main pulmonary artery and, in case 

 illustrated, would resemble that recorded from right ventricle. 



FIG. 10. Measurements and equations required for calcula- 

 tion of pulmonary blood flow, magnitude of left-to-right shunt, 

 and systemic blood flow from dilution curves recorded simulta- 

 neously from a systemic artery (for example, radial artery) 

 and main pulmonary artery after injection of indicator into 

 distal pulmonary artery in patient with left-to-right shunt via 

 ventricular septal defect. Pulmonary flow (Qp) is calculated 

 from initial forward ti'iangle portion of systemic arterial curve 

 (195). Fraction of pulmonary flow composed of shunted blood 

 (Fl-r) is ratio of area of forward triangle of pulmonary-artery 

 curve (BT.Cp)pA to that of forward triangle of curve recorded 

 simultaneously at systemic artery (BT.Cp)gA. Systemic flow Qs 

 is calculated by multiplying pulmonary blood flow (Qp) by 

 fraction of unshunted blood (i-F[_i{). 



dilution curve are readily apparent to visual inspec- 

 tion, this is not always true in cases of moderate 

 valvular regurgitation. Therefore methods have been 

 devised to quantitate objectively the changes produced 

 in dilution curves by valvular regurgitation. For 

 maximal discriminatory effectiveness these methods 

 must correct for the nonspecific changes in the 

 dilution curve that are produced by marked variations 

 in cardiac output and blood volume, and other factors, 

 such as occur in congestive failure of whatever cause. 

 The first attempt to cancel such nonspecific changes 

 was use of the ratio of the disappearance time to the 

 build-up time (DT/BT) by Broadbent & Wood (41 ). 

 Korner & Shillingford (155, 156) attempted to 

 extract the nonspecific effects of flow and volume on 

 the dilution curve by comparing the disappearance 

 slope and the "variance" (degree of dispersion) 

 measured from a particular curve with values for 

 these parameters predicted from regression equations 

 based on data obtained from normal subjects and 

 from patients with stenotic valvular disease. The 

 residual values for these two parameters of the curves 



after their extraction were then used to quantitate the 

 degree of regurgitation. However, efforts to quantitate 

 the volume of regurgitant flow in an individual 

 patient are subject to gross error, due to the uncon- 

 trolled effects of variations in the volume and dis- 

 tensibility in the chambers upstreain and downstream 

 to the incompetent valve (173, 280). 



Other attempts have been made better to locate and 

 quantitate valvular incompetence. One of the more 

 successful has been to inject the indicator into the 

 cardiac chamber immediately downstream from the 

 valve under study with sampling from the chamber 

 immediately upstream to this valve. The presence of 

 immediate-appearing dye indicates that the valve is 

 incompetent (fig. 12). An index of the amount of dye 

 regurgitated is obtained from the ratio of the areas of 

 the curves recorded from the chamber upstream to 

 the incompetent valve and from a simultaneousK- 

 recorded arterial dilution curve (16, 281). This index 

 is based on the assumption that there is uniform 

 mixing of dye in the chamber into which the dye is 

 regurgitated. It has been demonstrated, however. 



