654 



HANDBOOK OF PHVSIOLOOV 



CIRCULATION I 



pulmonary artery. When the regurgitation is severe 

 and long standing and has produced increased pulmo- 

 nary vascular resistance, this retrograde transmission 

 is rendered impossible or the v vk'ave becomes so 

 damped out that it cannot be identified in the pulmo- 

 nary arterial wedge tracing. 



Differentiation between mitral stenosis and insufficiency . 

 The great interest in physiological methods that has 

 been demonstrated in clinical work has been due 

 partly to the hope that the use of these methods in the 

 study of patients would aid in the differentiation 

 between various disorders, a hope that has only partly 

 been fulfilled. The expectation that the use of dilution 

 curves or pressure recordings for the differentiation 

 and quantitation of regurgitation in the atrioventricu- 

 lar valves has not led to any clear-cut result, although 

 much work has been done to modify the original 

 techniques. Several ways have been suggested to 

 evaluate the left atrial or pulmonary arterial wedge 

 tracing in these cases, but none has been completely 

 satisfactory. 



Allison & Linden (i) related the ratio of the pres- 

 sure difference between the peak of the v wave and 

 the z point to the peak v wave pressure to differentiate 

 between regurgitation and stenosis, and reported a 

 correct diagnosis in 59 of 61 patients. Owen & Wood 

 (158), studying the pulmonary wedge pressure, uti- 

 lized the rate of descent of the v wave to the height of 

 the preceding v wave, and reported excellent dis- 

 crimination between stenosis and incompetence. 

 Connolly & Wood (38) were unable to confirm this, 

 but these authors did find a close correlation between 

 the average peak v wave pressure and the degree of 

 regurgitation, as compared to the findings in patients 

 with mitral stenosis for equivalent mean pressures. 

 Neustadt & Shaffer (155) studied 54 left atrial pres- 

 sure pulse curves in 43 patients with mitral valvular 

 disease. All patients with mitral stenosis had an end- 

 diastolic gradient across the mitral valve. Fifty per 

 cent of the patients who had pure mitral insufficiency 

 also exhibited a similar gradient. Numerous ways of 

 analyzing the pulse contour or pres.sure le\'cl of tlic 

 left atrial pulse gave a poor separation between those 

 with and those without mitral regurgitation. The 

 most useful feature of the left atrial pulse was the rate 

 of y descent in its initial o. i sec related to the pressure 

 at the V point, but even this did not always significanli\ 

 characterize the patients with mitral incompetence. 



In a comparison of these different methods of 

 judging the degree of mitral regurgitation, where also 

 Ihc methods of Kent ct al. (114), who used the differ- 

 ence of (' wave and v wa\e pressures, and those of 



McMichael & Shillingford (150), using the difference 

 between c wave and .v wave pressures were incor- 

 porated, Marshall et al. (142) found that no simple 

 method could be used for discrimination between 

 mitral incompetence and mitral stenosis. However, a 

 significant correlation could be demonstrated be- 

 tween many different parameters of the left atrial 

 pulse and the degree of mitral regurgitation. These 

 authors suggested that multiple-variable analysis, 

 using various properly weighted combinations of these 

 parameters, might improve the discrimination ob- 

 tained; a hope that thus far has not been fulfilled. 



Braunwald et al. (30) studied the left atrial pressure 

 pulse in dogs before and during acute mitral incompe- 

 tence at rest and during elevation of the peripheral 

 resistance by infusion of norepinephrine. In the 

 absence of mitral regurgitation, striking elevations of 

 aortic pressure raised the v point of the left atrial 

 tracing only slightly. In dogs with slight mitral in- 

 competence (little or no elevation of the v points) 

 the left atrial v point was strikingly elevated when 

 aortic pressure was raised. These authors then stud- 

 ied 7 patients without mitral insufficiency and 13 

 with, and found a much more marked increase of 

 left atrial pressure (mean and v point) in those with 

 mitral incompetence as compared to those without 

 (pure mitral stenosis with elevated left atrial pres- 

 sure). 



Studies of atrial \olumc pulsations have also been 

 used in order to differentiate between stenosis and 

 incompetence with varying degrees of success. The 

 simultaneous recording of the pressures in the left 

 atrium and ventricle has gained increasing impor- 

 tance after the introduction of left heart puncture, 

 either through the left bronchus or from the back 

 (i, 16, 17). The curves obtained during these circum- 

 stances have, however, usually been difficult to inter- 

 jsret, and the value of this method for routine clinical 

 work or for exact hemodynamic studies has been dis- 

 appointing. Moscovitz et al. (152) recorded left 

 atrial and ventricular pressures simultaneously during 

 chest surgery. In six control cases simultaneous record- 

 ing of the pressure pulse on the left side of the heart 

 was obtained. Virtually no pressure gradient between 

 the left atrium and the left ventricle was found 

 throughout the diastolic period. This was true also 

 clm-ing the period of greatest mitral flow, immediately 

 after the opening of the mitral valve. 



In seven cases of mitral stenosis similar tracings 

 were obtained before and after surgical opening of 

 the stenosed \al\e. The mitral valve filling pressure 

 gradient was between 5 and 20 mm Hg before sur- 



