Arterial elastance and heart-arterial coupling in aortic regurgitation are determined by aortic leak severity

in American Heart Journal (2002), 144(4), 568-576

Background In aortic valve regurgitation (AR), aortic leak severity modulates left ventricle (LV) arterial system interaction. The aim of this study was to assess (1) how arterial elastance (E-a ... [more ▼]

Background In aortic valve regurgitation (AR), aortic leak severity modulates left ventricle (LV) arterial system interaction. The aim of this study was to assess (1) how arterial elastance (E-a), calculated as the ratio of LV end-systolic pressure and stroke volume, relates to arterial properties and leak severity and (2) the validity of E-a/E-max (with E-max the slope of the-end-systolic pressure-volume relation) as a heart-arterial coupling parameter in AR. Methods and Results Our work is based on human data obtained from a study on vascular adaptation in chronic AR. These data allowed us to assess the parameters of a computer model of heart-arterial interaction. In particular, total peripheral resistance (R) and aortic leak severity-expressed as leak resistance (R-L,R-ao)-were quantified for different patient subgroups (group I/IIa/IIb: E-max = 2.15/0.62/0.47 mm Hg/mL; E-a = 1.24/0.66/0.90 mm Hg/mL; R = 1.9/0.6/0.85 mm Hg-s/mL, R-L,R-ao = 0.35/0.05/0.20 mm Hg-s/mL). A parameter study demonstrated that R-L,R-ao was the main determinant of E-a. With all other parameters constant, valve repair would increase E-a to 2.81, 1.08, and 1.54 mm Hg/mL in groups I,IIa, and IIb, respectively. For a given E-a/E-max, LV pump efficiency (estimated as the ratio of stroke work and LV systolic pressure-volume area) was lower than the theoretical predicted value, except for the simulations with intact aortic valve. Conclusions In AR(a) E-a is determined by aortic leak severity rather than by arterial system properties. Using E-a/E-max as a coupling parameter in general or as a mechanico-energetic regulatory parameter in particular is questionable. [less ▲]

Effet de l'embolie pulmonaire aiguë sur le couplage ventriculo-artériel pulmonaire chez le porc

in Réanimation (2001), 10(1), 9164

Effect of hemodiafiltration on pulmonary hemodynamics in a model of porcin endotoxin shock

in Journal of the American Society of Nephrology [=JASN] (2001), 12