whether the inability of these individuals to augment stroke volume is caused by a decrease in the ability of the heart to increase diastolic filling , by a decrease in systolic pump function caused by an increased afterload , by intrinsic myocardial contractile defects , or by a greater diminution of the cardiovascular response to beta-adrenergic stimuli is presently unknown .
C0018787
heart
C0027061
myocardial