Long axis function in disease

Although longitudinally directed fibres-situated mainly in the subepicardium and subendocardium regions of the left and right ventricular free walls and the papillary musclescomprise only a small proportion of the total ventricular myocardial mass, they play a major role in the maintenance of normal ejection fraction and in determining atrioventricular interactions. 1 Not surprisingly, therefore, loss of longitudinal fibre function leads to characteristic disturbances.