Cardioprotection from intradialytic exercise: a randomized trial

Abstract

Background and hypothesis Left ventricular (LV) regional wall motion abnormalities (RWMAs) related to transient ischemic events are well documented during hemodialysis (HD). Intradialytic exercise (IDE) reduces the global occurrence of HD-induced RWMAs. However, the regionalization of its cardioprotective effects within the LV wall, and its underlying mechanisms remain unclear. Methods We conducted a prospective, crossover, randomized trial: 72 patients underwent two sessions of standard HD (HD-CONT) and HD with 30 minutes of aerobic exercise (HD-EX). Segmental longitudinal strains (LS) were measured before (T0) and at peak stress (30 min before HD ending, Tpeak). An 18-segment model identified RWMAs, defined as a 20% LS reduction at T peak compared to T0. To evaluate the impact of circulating factors, we measured fractional shortening, Ca2+ transients and spontaneous Ca2+ waves (SCaW) following anoxia/reoxygenation (A/R) in isolated rat cardiomyocytes pre-treated with human plasma ultrafiltrates (obtained at Tpeak in both sessions). Results IDE significantly reduced RWMAs during HD-EX compared to HD-CONT (estimated difference: 1.1 segment, 95%CI: 0.33/1.90, P =.009). A baso-apical gradient of RWMAs was observed during HD-CONT, with higher prevalence at the apex compared to the base (P =.03). This gradient was abolished during HD-EX, suggesting greater apical cardioprotection. Pre-treatment of cardiomyocytes with ultrafiltrates from HD-EX improved fractional shortening, Ca2+ handlings and SCaW following A/R compared to cells pre-treated with ultrafiltrates from HD-CONT. Conclusions IDE limits HD-induced RWMAs, and circulating humoral factors may contribute to this cardioprotection. IDE-induced benefits on RWMAs were greater at the apex. Further studies are needed to elucidate the mechanisms underlying the heterogeneous benefits of IDE on regional myocardial function.