Differential effects of afterload on left ventricular long- and short-axis function: Insights from a clinical model of patients with aortic valve stenosis undergoing aortic valve replacement
Received 7 May 2009; accepted 13 July 2009. published online 24 August 2009.
Background
The effects of left ventricular (LV) afterload on longitudinal versus circumferential ventricular mechanics are largely unknown. Our objective was to examine changes in LV deformation before and early after aortic valve replacement (AVR) in patients with severe aortic valve stenosis (AS).
Methods
Paired echocardiographic studies before and early (7 ± 3 days) after AVR were analyzed in 45 patients (age 67 ± 12 years, 49% men) with severe AS and normal LV ejection fraction without segmental wall motion abnormalities. Longitudinal myocardial function was assessed from 3 apical views (average of 18 segments). Circumferential function was assessed at mid and apical levels (averaging 6 segments per view). Strain, strain rate (SR), and LV twist (relative rotation of the mid and apex) were measured using 2-dimensional strain software.
Results
Early post-AVR, (1) LV size and LV ejection fraction did not change; (2) longitudinal systolic strain, which was lower than normal before AVR, increased (−12.8 ± 1.7 to −15.9 ± 2.2, P < .05), whereas mid-LV circumferential strain, which was higher than normal, decreased (−27.0 ± 5.1 to −22.3 ± 4.9, P < .05); (3) longitudinal early diastolic SR increased (0.6 ± 0.1 to 0.7 ± 0.2, P < .05), whereas mid-LV circumferential diastolic SR decreased (1.2 ± 0.5 to 1.0 ± 0.3, P < .05); and (4) LV twist increased (3.7° ± 2.1° to 6.1° ± 2.9°, P < .05).
Conclusions
Aortic valve stenosis causes differential changes in longitudinal and circumferential mechanics that partially normalize after AVR. These findings provide new insights into the mechanical adaptation of the LV to chronic afterload elevation and its response to unloading.
aDepartment of Cardiology, Rambam Health Care Campus, Haifa, Israel
bDepartment of Cardiovascular Surgery, Rambam Health Care Campus, Haifa, Israel
cTechnion – Israel Institute of Technology, Haifa, Israel
dUniversity Health Network, University of Toronto, Toronto, Canada
Reprint requests: Shemy Carasso, MD, Non-invasive cardiology unit, Department of Cardiology, Rambam Health Care Campus, POB 9602, Haifa 31096, Israel
ABSTRACT