Background: Expanded intravascular volume in the patient with chronic renal insufficiency (CRI) increases cardiac volume and impose more wall tension on endocardium. We hypothesized acute volume reduction with ultrafiltration (UF) has different effects on Subepicardium (Mepi) and subendocaridum (Mendo) and increase the gradient of strain between two myocardial layers.
Methods and results: Thirteen, cardiovascular disease-free, hemodialysis-dependent patients with chronic renal insufficiency were enrolled (Male:Female=5:13) and 13 pairs of echocardiographic evaluation were acquired before and after UF. Mean age, dry body weight, and the amount of UF were 47.2 years, 56.0kg and 2.4L. Color coded tissue Doppler images were obtained from apical four chamber view and two sample volumes (Size: 5×3mm) were respectively placed in subepicardium and subendocardium of mid anterolateral wall of left ventricle (LV). Immediately after UF, LV end diastolic volume, left atrial volume (LAV), the ratio of early mitral inflow velocity and mitral annular tissue velocity [E/Em] were reduced (81.3ml to 73.8ml, p=0.036; 61.1ml to 52.0ml, p=0.01; 18.1 to 15.9, p=0.037), while LV stroke volume (SV) and LV ejection fraction (LVEF) were not changed (47.4 to 44.1ml, p=0.22; 59.9 to 60.8%, p=0.529). Longitudinal strain of endocardium (SLendo) was not changed (-15.5±6.5 vs -16.8±8.1, p=0.622), while longitudinal strain of subepicardium (SLepi) (-15.5±6.3 vs -11.6±4.4, p=0.019) decreased. Consequently, strain gradient between Mendo and Mepi was newly developed after UF (0.04 to -5.3, p=0.03). Strain rate, tissue velocity didn’t show any significant change.
Conclusion : Rapid reduction of cardiac preload by UF resulted in less SLepi, stationary SLendo and subsequent increase of SL gradient between Mepi and Mendo.. Less strain without loss of SV and LVEF means reduced oxygen demand and improved myocardial efficiency, although clinical implication of increased strain gradient in the myocardium remains unclear. Reference values of strain gradient in the normal population and following studies with larger number are needed.
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