Dietary Nitrate for Heart Failure

Detailed Summary

The purpose of this study is to determine if nitrates in a food, in this case - beetroot juice (BRJ) - is efficacious in improving exercise tolerance and/or peak power in patients with heart failure. The investigators will also determine if BRJ improves blood pressure, exercise efficiency, vascular and muscle function, and whether blood levels of nitrates increase hourly for a total of 4 hours after BRJ ingestion. A secondary aim is to determine if BRJ-derived nitrates are still effective at 1, 2 and 4 weeks after starting treatment. A tertiary aim is to determine the variation in the 6 minute walk test. Subjects will answer a basic medical information sheet and undergo a 6-minute walk test. After at least a 48 hours rest, subjects will be asked to repeat the 6 minutes' walk. The investigators will (1) determine if BRJ (as compared to placebo) improves peak power output in heart failure patients and controls (at \~ 1½ to 2 hours after ingestion); (2) compare the changes in cardiac muscle (on average \~ 8-12 hours after) BRJ or placebo ingestion in patients who will be undergoing an left ventricle (LV) assist device placement for clinical purposes. (a cross-sectional study); (3) determine if BRJ decreases elevated pulmonary artery (PA) pressures or improves vascular and/or microvascular function (at \~ 1½ - 2 hours after ingestion) in patients who are already coming in for a PA catheter placement for clinical purposes; (4) compare the physiological changes after BRJ ingestion in non-heart failure control subjects with those of patients with heart failure. Endpoints measured at the same time points after ingestion. The investigators hypothesize (1) that patients with heart failure and controls will have improved exercise capacity and power at lower oxygen cost (and thereby greater efficiency) \~ 1½- 2 hours after ingesting beet juice (BRJ) than after ingesting placebo (beet juice without nitrates); (2) that patients with heart failure will have a greater physiologic response to BRJ than non-heart failure controls since the former have worse physiological function to start with; (3) that patients with high pulmonary artery pressures will have an improvement in the pressures after ingestion with BRJ; (4) that myocardial perfusion will be higher after BRJ ingestion than after placebo; (5) that cyclic guanosine monophosphate (cGMP) levels will be increased in left ventricle assist device (LVAD) samples after BRJ ingestion compared with placebo.

Study Details

Timeline

Interventions