[Hemodynamic response to diurnal activities of patients with myocardial infarction evaluated by ambulatory monitoring of systolic time intervals using ear densitography].

The purpose of this study was (1) to assess the hemodynamic changes during daily activities by 24-hour continuous ear-densitographic monitoring (Holter EDG) in 14 patients with acute myocardial infarction (MI), and (2) to define the changes in left ventricular performance during and after acute upright posture in 35 patients with old MI. Ninety-seven percent of the daily activities could be reliably measured by ambulatory monitoring of systolic time intervals (STI) and the most significant change in STI was observed during defecation. The ratio of preejection period to left ventricular ejection time (PEP/LVET) increased significantly during defecation (0.42 +- 0.09----0.50 +- 0.09, p less than 0.05), but heart rate either increased (5 patients) or decreased (4 patients). Though there was no change in PEP/LVET during sleep, walking and washing the face and hands, it tended to increase during eating and urinating. Acute upright posture caused sudden acceleration of the heart rate, and increased PEP/LVET immediately (0.36 +- 0.05----0.39 +- 0.06, p less than 0.005). The latter further increased immediately after sitting (0.36 +- 0.05----0.41 +- 0.07, p less than 0.001) and 1 min after sitting (0.36 +- 0.05----0.43 +- 0.07, p less than 0.001), but it was stable thereafter. Thus, abrupt changes in these parameters indicate that changes both in neural activity and venous return are virtually instantaneous. We concluded that the Holter EDG will facilitate the evaluation of daily activities of patients, and that the information obtained in this study could be valuable in understanding the physiology and hemodynamics of patients recovering from acute MI.