Blood pressure and vasomotor responses to sympathetic stimuli in patients with chronic myocardial infarction.

The responses of resistance and capacitance vessels of skin and muscle, and of blood pressure to reflex influences mediated by the sympathetic system were investigated in a group of 63 male patients in a chronic phase of myocardial infarction. In the group of patients with MI, as compared to the controls: (1) the reactive increase of systolic BP and heart rate was significantly smaller but longer lasting after cessation of the stimuli; (2) the vasoconstrictory reactions in skin were significantly prolonged in resistance as well as in capacitance segments of vascular bed; and (3) the resting blood flow in muscle was significantly lower and the vasodilatation during an emotional reaction was less pronounced and shorter. Possible underlying mechanisms of this vasomotor pattern are discussed.