Figure 1. Adjustments of global and regional ventricular mechanics with hypoxia, at rest and during exercise.

A, global left ventricular (LV) mechanics are elevated with both acute and prolonged hypoxia, where the LV twist is often augmented as a result of increased rotation at both the base and apex. B, recent work has assessed regional myocardial mechanics to determine whether subendocardial (square symbols, dashed line) vs. subepicardial mechanics (open circle symbols, dotted line) become impaired with hypoxia (HX) compared to normoxia (NX). There appear to be no indications of subendocardial dysfunction, as previously hypothesized, given the consistent increase in local strain in the basal (left), apical (middle) and longitudinal axes (right with acute and prolonged hypoxia. C, the increases to systolic mechanics are largely attributable to amplified sympathetic activation, as determined via administration of a cardiac‐specific ß‐adrenergic receptor blockade (ß₁‐AR block). D, during exercise, LV twist mechanics become augmented from an elevated hypoxic baseline but reach a peak exercising twist similar to sea level. Representative data from Williams et al. (2019) and Stembridge et al. (2015).