Key result
Diastolic foot strike synchronization increases stroke volume ~8% versus systolic synchronization in HF patients with CRT.
Why the study?
Patients with chronic CHF have persistent exercise intolerance despite medical therapy and CRT, prompting investigation into whether synchronizing steps with cardiac phase enhances exercise hemodynamics.
Does synchronizing foot strike to the diastolic phase of the cardiac cycle improve exercise stroke volume and cardiac output in patients with CHF and CRT?
RCT (n=10)
randomly assigned
Does synchronizing foot strike to the diastolic phase of the cardiac cycle improve exercise stroke volume and cardiac output in patients with CHF and CRT?
Synchronizing foot strike to the diastolic phase of the cardiac cycle during walking acutely improves stroke volume, cardiac output, and afterload in patients with heart failure and CRT.
Answers are grounded in this paper and cite their sources.
Diastolic foot strike synchronization augments exercise stroke volume in HF with CRT; extends acute hemodynamic benefits to ambulatory walking.
BACKGROUND: Despite advances in medical and cardiac resynchronization therapy (CRT), individuals with chronic congestive heart failure (CHF) have persistent symptoms, including exercise intolerance. Optimizing cardio-locomotor coupling may increase stroke volume and skeletal muscle perfusion as previously shown in healthy runners. Therefore, we tested the hypothesis that exercise stroke volume and cardiac output would be higher during fixed-paced walking when steps were synchronized with the diastolic compared with systolic portion of the cardiac cycle in patients with CHF and CRT. METHODS: Ten participants (58±17 years of age; 40% female) with CHF and previously implanted CRT pacemakers completed 5-minute bouts of walking on a treadmill (range, 1.5–3 mph). Participants were randomly assigned to first walking to an auditory tone to synchronize their foot strike to either the systolic (0% or 100±15% of the R-R interval) or diastolic phase (45±15% of the R-R interval) of their cardiac cycle and underwent assessments of oxygen uptake (V̇ o 2 ; indirect calorimetry) and cardiac output (acetylene rebreathing). Data were compared through paired-samples t tests. RESULTS: V̇ o 2 was similar between conditions (diastolic 1.02±0.44 versus systolic 1.05±0.42 L/min; P =0.299). Compared with systolic walking, stroke volume (diastolic 80±28 versus systolic 74±26 mL; P =0.003) and cardiac output (8.3±3.5 versus 7.9±3.4 L/min; P =0.004) were higher during diastolic walking; heart rate (paced) was not different between conditions. Mean arterial pressure was significantly lower during diastolic walking (85±12 versus 98±20 mm Hg; P =0.007). CONCLUSIONS: In patients with CHF who have received CRT, diastolic stepping increases stroke volume and oxygen delivery and decreases afterload. We speculate that, if added to pacemakers, this cardio-locomotor coupling technology may maximize CRT efficiency and increase exercise participation and quality of life in patients with CHF.
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Wakeham et al. (2023) conducted an RCT in chronic congestive heart failure (n=10). Diastolic foot strike synchronization vs. Systolic foot strike synchronization was evaluated on stroke volume (p=0.003). Diastolic foot strike synchronization during walking increased stroke volume (80 vs 74 mL; P=0.003) compared with systolic synchronization in patients with heart failure and CRT.
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