The hemodynamic effects of acute aortic regurgitation into a stiffened left ventricle resulting from chronic aortic stenosis.
Acute aortic regurgitation (AR) post-chronic aortic stenosis is a prevalent phenomenon occurring in patients who undergo transcatheter aortic valve replacement (TAVR) surgery. The objective of this work was to characterize the effects of left ventricular diastolic stiffness (LVDS) and AR severity on LV performance. Three LVDS models were inserted into a physiological left heart simulator. AR severity was parametrically varied through four levels (ranging from trace to moderate) and compared with a competent aortic valve. Hemodynamic metrics such as average diastolic pressures (DP) and reduction in transmitral flow were measured. AR index was calculated as a function of AR severity and LVDS, and the work required to make up for lost volume due to AR was estimated. In the presence of trace AR, higher LVDS had up to a threefold reduction in transmitral flow (13% compared with 3.5%) and a significant increase in DP (2-fold). The AR index ranged from ∼42 to 16 (no AR to moderate AR), with stiffer LVs having lower values. To compensate for lost volume due to AR, the low, medium, and high LVDS models were found to require 5.1, 5.5, and 6.6 times more work, respectively. This work shows that the LVDS has a significant effect on the LV performance in the presence of AR. Therefore, the LVDS of potential TAVR patients should be assessed to gain an initial indication of their ability to tolerate post-procedural AR.
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia;
Ikechukwu
I
Okafor
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia;
Vrishank
V
Raghav
Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia;
Prem
P
Midha
Division of Cardiology, Emory University Hospital Midtown, Atlanta, Georgia; and Atlanta Veterans Affairs Medical Center, Decatur, Georgia.
Gautam
G
Kumar
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia; ajit.yoganathan@bme.gatech.edu.
Ajit
A
Yoganathan
D001021:Aortic Valve / Q000503:physiopathology; D001022:Aortic Valve Insufficiency / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D014655:Vascular Resistance / Q000502:physiology; D059289:Vascular Stiffness / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology
AR index; aortic regurgitation; left heart simulator; left ventricle diastolic stiffness; transcatheter aortic valve replacement