The phenomenon ofintermittent myocardial ischemia and myocardial reserve inmyocardial infarction survivors

Abstract

Aim. To study coronary and myocardial reserves in myocardial infarction survivors (MIS) with consideration of development of intermittent ischemia during transesophageal pacing (ТЕР). Material and methods. 320 MIS were examined 1.5-2 months after myocardial infarction onset. 30 healthy male volunteers served control. Stepwise overdrive ТЕР was made in all the examinees with parallel estimation of central hemodynamics by tetrapolar chest rheography with assessment of systolic and diastolic parameters. Results. In the course of ТЕР, 39.4% MIS developed intermittent ischemia (II) at frequencies HOMO imp/min. II presented as a significantly depressed ST segment on ECG. There was a simultaneous lengthening (1.4-fold) of diastole and a fall (1.5-fold) of end-diastolic pressure in the left ventricle (EDP). At frequencies 140-160 imp/min the length of the diastole shortened while EDP rose. Conclusion. The II phenomenon demonstrates a key role of coronary reserve. Changes in coronary and myocardial reserves during ТЕР in II development are interrelated. They may represent unknown adaptive mechanisms of the myocardium protecting against unfavourable outcomes of ischemic episodes.

Keywords

• myocardial infarction
• intermittent ischemia
• hemodynamics
• diastole