- Poster presentation
- Open Access
Afterload excess and myocardial performance
© Jayam et al; licensee BioMed Central Ltd. 2013
- Published: 30 January 2013
- Semimajor Axis
- Myocardial Performance
- Left Ventricular Wall Thickness
- Contractile State
- Adverse Remodel
Systolic circumferential and longitudinal strain(CSt%, LSt%) are widely used to assess myocardial performance, but their afterload dependence has not been well characterized. Using geometric estimates of left ventricular (LV) circumferential and meridional wall stress(CWS, MWS) as indices of afterload at the myocardial level, we compared LV CSt and LSt to estimates of CWS and MWS in normals (NL, n= 39, 46% female, age 54.6+/-14.6 yrs) and patients with dilated cardiomyopathy (DCM, n= 35, 23% female, age 50.8+/-15.0 yrs, EF 27.2+/-10.8%).
Breath-hold retrospectively gated SSFP cine images in short and long axis planes and cuff systolic blood pressure(P) during imaging were obtained and mid LV and "global" (average of basal, midLV and apical) CSt% and LSt% determined using feature tracking (2D CPA MR, TomTec Imaging Systems, Munich). Mid-LV CWS and MWS were estimated using Mirsky's published formulae (CWS= P(B/h)[1 - (B2/2A2) - (h/2b); where h=end-systolic(ES) LV wall thickness, A= ES midwall semimajor axis ([L + h]/2), B= ES midwall semiminor axis ([D + h]/2)) and MWS= PRi/(2h(1+h/2Ri) where Ri= short axis LV radius).
Global Circumferential and Longitudinal Strains and Wall Stress
Global Circ Strain(%)
Circ Wall Stress x103dynes/cm2
Global Long. Strain(%)
We conclude that afterload excess is a major contributor to impaired systolic function in DCM and normalization of contractile state and myocardial composition alone may not restore normal function. Consideration of effects of afterload excess, inadequate hypertrophy and adverse remodeling on myocardial strain is essential in the evaluation of pathophysiology.
This study was supported by the St. Francis Research Foundation
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