Abstract 16311: Resistance Training Improves Cardiac Output, Exercise Capacity and Tolerance to Positive Airway Pressure in Fontan Physiology
Adults with “single ventricle” hearts palliated with a Fontan procedure (SVH-Fontan) have no sub-pulmonary ventricle and thus depend exquisitely on the respiratory bellows and peripheral muscle pump for cardiac filling. We hypothesised that resistance training to augment the peripheral muscle pump might improve cardiac filling and stroke volume (SV), reduce the inspiratory-dependence of IVC return to the heart and thus improve exercise capacity as well as cardiac output on constant positive airway pressure (CPAP). Eleven young adults with SVH-Fontan (32 +/- 2 years, mean +/- SEM) had cardiac magnetic resonance imaging (MRI) and exercise testing (CPET); in addition 6 had muscle MR spectroscopy. Six underwent 20 weeks of high-intensity resistance training (mean 43 sessions, 60 minutes each); others were non-exercising controls; after training CPET and MR spectroscopy were repeated. Four trainers had MRI with real-time flow measurement at rest, exercise and on CPAP in the trained state and following 12 months detraining. In the trained state, muscle strength increased by 43% (p=0.002) and total muscle mass was augmented (by 1.94kg, p=0.003). Peak VO2 increased (by 183ml/min p=0.02) and calf muscle phosphocreatine recovery tended to improve (p=0.09). After detraining, calf muscle mass and peak workload had fallen significantly (p<0.01 for all) as did peak VO2 (2.72 vs: 2.18 L/min, p<0.001) and oxygen pulse, a surrogate for SV (16% lower, p=0.005). Furthermore after detraining, SV at MRI decreased at rest (by 11mls, p=0.01) and during moderate-intensity exercise (by 16mls, p=0.04); inspiratory-dependent IVC blood return during exercise was 40% higher (p=0.004). On CPAP, cardiac output was lower in the detrained state (101 vs: 77 ml/sec, p=0.03). Thus, resistance muscle training improves muscle mass, strength and is associated with improved cardiac filling, stroke volume, exercise capacity and cardiac output on CPAP, in young adults with Fontan-type circulation.
- © 2012 by American Heart Association, Inc.