Systolic thickening increases from subepicardium to subendocardium

Abstract

The aim was to determine the relation between systolic function and depth below the epicardial surface, using pulsed Doppler crystals. Systolic excursion in mm was measured at multiple depths below the epicardial surface. Measurements were made during control conditions. Thirty four anaesthetised mongrel dogs were studied. A total of 333 measurements of systolic excursion were made during control conditions at 1 to 3 crystal sites per dog. Two models were constructed; the model which assumed a quadratic relation between depth (d) and systolic excursion (EX) (EX = 0.498 + 0.176d + 0.006d2) fit the data better than did a model which assumed a linear relation (EX = -0.0716 + 0.254d). These data support the prediction from geometric models that systolic excursion increases in a non-linear fashion from subepicardium to subendocardium.