Psychophysiological mechanisms in silent myocardial ischaemia.

Six levels of coronary pain are defined and for each of them explanations for absence of pain in asymptomatic myocardial ischaemia are given: Level I: Myocardial ischaemia which can be less pronounced in amount during asymptomatic episodes. Level II: Adequate stimulus (chemical, mechanical) where biosynthesis of algogesic substances, degree of local mechanical involvement and spatial distribution may be different. Level III: For neuronal encoding the intensity theory is mainly for coronary pain, presupposing a central pain threshold which is higher in asymptomatic patients. Level IV: Conduction of painful information may be interrupted by destruction of afferent nerve ways. Level V: Spinal transmission: resting tone and ability to activate neural and humoral (endorphinergic) pain inhibition systems are stronger in asymptomatic patients. Level VI: Central processing: cognitive mechanisms (coping style) affect perception of coronary pain with differences in symptomatic and silent myocardial ischaemia.