Fig. 2.

Heterogeneous responses to direct and reflex sympathetic nerve stimulation in scar, border zone, and preserved myocardium. Image on the left depicts an electroanatomic map of a patient with a large anterior wall infarction (with dense scar in gray, preserved myocardium in purple, and border zone in other colors) and the location of a multi-electrode catheter. The image on the right shows the activation recovery interval (ARI) at baseline and in response to reflex (nitroprusside) and direct (isoproterenol) sympathetic stimulation. In preserved myocardium, direct activation via adrenergic receptors is fairly uniform, however in the border zone and scar regions, this response is heterogeneous, reflecting varying degree of adrenergic receptor responses in adjacent myocardium. In response to reflex sympathetic stimulation induced by cardiac sympathetic nerves, significant heterogeneity is seen across the entire spectrum of scar, border zone, and even “preserved” myocardium.

Adapted from Vaseghi M, Lux RL, Mahajan A et al. Am J Physiol Heart Circ Physiol 2012, 302(9):H1838–46.