whom clinical opinion was in doubt. Not even Gorlin 

 thus wants to advocate use of the formula for exact 

 hemodynamic measurements. 



In aortic or pulmonic stenosis the formula is 



PVA = 



CO /SEP 



i.o X 44.5V«r,„. - PA„ 



where 



PVA 



CO 



SEP 



1.0 



RV,„ 

 PA,„ 



= pulmonic valve area, cm- 



= cardiac output, ml/min 



= systolic ejection period, sec/min 



= empiric constant 



= right ventricular systolic mean pressure, mm Hg 



= pulmonary arterial systolic mean pressure, mm Hg 



For aortic valve area right heart pressures are sub- 

 stituted with left heart values. 



The formula for semilunar valves is less inexact 

 than the one for atrioventricular valves, although the 

 uncertainty introduced b\ the undetermined degree 

 of regurgitation and the presence of turbulent flow 

 decreases its applicability in hemodynamic research. 



ESTIM.^TION OF V.^LVUL.'SiR INCOMPETENCE 



This estimation has been made from: a) Pressure 

 curves and has been used mostly in the case of atrio- 

 ventricular \alves where analysis of the atrial pressure 

 tracing has shed some light on the presence or ab- 

 sence of incompetence (5, 167). b) Dye dilution curves 

 with an indicator introduced upstream from the 

 leaking valve and the dilution curve constructed by 

 sampling downstream, or with indicator introduced 

 in the chamber immediately downstream from the 

 leaking valve with collection immediatelv upstream 

 from the valve (8, 35, 36, 57, 99-101, 117, 120, 

 121, 129, 137, 145, 182, 183). () Palpation of the 

 leaking valve during surgery. In combination with 

 data obtained during right heart catheterization, 

 this has been used to calculate the regurgitant valve 

 area and the regurgitant flow (114, 149). 



Hydraulic Formula 



Gorlin (■/ al. (86) have derived a hydraulic formula 

 for the calculation of the mitral regurgitant area, 

 using the principle that total ventricular flow equals 

 regurgitant flow plus aortic flow, where the regurgi- 

 tant flow is calculated from the mitral orifice area for 

 forward flow as determined by the surgeon at the 

 time of operation. 



STENOSIS AND INSUFFICIENCY 



The final formulas were: 



a) Fr = MVA X DFP X yy/pC-^ - CO 



647 



^j^^ ^ MVAXDFPX3WPC-S-CO 

 SEP X sWba^ - PC 



where 



Fr 



MVA 



DFP 



3' 

 PC 



CO 

 MRA 

 SEP 

 36 



BA.„. 



= regurgitant blood flow, liters/min 



= mitral valve area (forward flow), cm- 



= diastolic liliing period, sec/min 



= empirical constant 



= pulmonary arterial wedge pressure, mm Hg 



= assumed left ventricular mean diastolic pressure, 



mm Hg 



= aortic output, liters/min 



= mitral regurgitant area, cm- 



= systolic ejection period, sec/min 



= empirical constant 



= brachial arterial systolic mean pressure, mm Hg 



This formula lias been used by Dexter and his group 

 (149) in about 50 cases of mitral valvular disease. 

 Areas calculated in the same individual under diflfer- 

 ent circulatory states checked within o.i to 0.2 cm^. 

 Regurgitant areas ranging from 0.3 to 0.9 cm- were 

 calculated. They were always less than the mitral 

 valve forward flow area and usually about one- 

 fourth to one-tenth the size of the aortic valve. This 

 formula has the same error as the formula of Gorlin 

 and Gorlin for calculating stenotic valve areas. To 

 this are added several assumptions and the inexact 

 method of determining the mitral valve forward flow 

 area from palpation during surgery. Although the 

 approach to the problem is ingenious, the derived 

 formula has not been used for exact measurements. It 

 seems appropriate to cite Wiggers (203), who states 

 regarding myocardial contractility in mitral insuffi- 

 ciency: "Attention may be directed to the fact that 

 since the rate of pressure increase is such an important 

 determinant of the \olume regurgitated, calculations 

 of the size ot leaking orifices from laws isased on static 

 equations do not necessarily apply to the beating 

 heart." 



Indicator Dilution Teclmiques 



Application of the Stewart-Hamilton method for 

 cardiac output determination (96, 97, 190) to studies 

 of valvular backflow has been used by several investi- 

 gators (33-36, 57, 63, 100, 1 01, 104, 116, 120, 122- 

 124, 129, 130, 141, 142, 145, 161, 182, 183, ig8, 207, 

 210-212). Korner & Shillingford (120-122, 154) have 



