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.
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 degrees +/- 2.1 degrees to 6.1 degrees +/- 2.9 degrees , 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.
Carasso
Shemy
S
Department of Cardiology, Rambam Health Care Campus, Haifa, Israel. s_carasso@rambam.health.gov.il
Cohen
Oved
O
Mutlak
Diab
D
Adler
Zvi
Z
Lessick
Jonathan
J
Reisner
Shimon A
SA
Rakowski
Harry
H
Bolotin
Gil
G
Agmon
Yoram
Y
D000368:Aged; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013318:Stroke Volume / Q000502:physiology*; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*