Abstract 14528: Effects of Organic and Inorganic Nitrate on Aortic and Carotid Hemodynamics in Heart Failure and Preserved Ejection Fraction
Background: Organic nitrate therapy reduces physical activity, without enhancing exercise capacity in heart failure with preserved ejection fraction (HFpEF). In contrast, inorganic nitrate therapy increases exercise capacity in HFpEF. We assessed the effects of organic and inorganic nitrates on: (1) wave reflections arriving at the central aorta; (2) Carotid bed vascular properties, in HFpEF.
Methods: Carotid and aortic pressure-flow relations were studied before and after the administration of 0.4 mg of sublingual nitroglycerin (NTG; n=26). We also performed a placebo-controlled cross-over trial of a single dose of inorganic nitrate administration (12.9 mmil; n=16).
Results: NTG did not consistently reduce wave reflections arriving at the proximal aorta across the first 3 harmonics (change in real part of reflection coefficient, 1st harmonic:-0.09; P=0.01; 2nd harmonic:-0.045, P=0.16; 3rd harmonic:+0.087; P=0.05), but produced profound vasodilation in the carotid territory, with a marked reduction in carotid bed vascular resistance (14092 vs. 11024 dynes·s/cm5; P=0.007) and carotid artery characteristic impedance (2555 vs. 1663 dynes·s/cm5; P=0.007). Inorganic nitrate administration, in contrast, produced consistent reductions in wave reflections across the first 3 harmonics (change in real part of reflection coefficient, 1st harmonic: -0.12; P=0.03; 2nd harmonic:-0.11, P=0.01; 3rd harmonic:-0.087; P=0.09) and did not reduce carotid bed vascular resistance (12819 vs. 13175 dynes·s/cm5; P=0.80) or carotid artery characteristic impedance (2221 vs. 2138 dynes·s/cm5; P=0.71).
Conclusions: NTG produces marked vasodilation in the carotid circulation, with inconsistent effects on wave reflections arriving at the central aorta. Inorganic nitrate, in contrast, produces consistent reductions in wave reflections arriving at the central aorta, without significant cerebrovascular dilatation. These hemodynamic differences may underlie the different effects on exercise capacity and side effect profile of inorganic vs. organic nitrate in HFpEF.
Author Disclosures: J.A. Chirinos: Research Grant; Significant; NIH, American College of Radiology Network, Fukuda Denshi, Bristol Myers Squibb, Microsoft and CVRx Inc. Other Research Support; Modest; Fukuda Denshi, Withings, Atcor Medical. Consultant/Advisory Board; Modest; Fukuda Denshi, Microsoft Research, Merck and Vital Labs. Consultant/Advisory Board; Significant; Bristol Myers Squibb, OPKO Healthcare. F. Londono-Hoyos: None. M. Beraun: None. P. Haines: None. I.V. Md: None. S. Varakantam: None. T.S. Phan: None. T.P. Cappola: None. K.B. Margulies: None. R.R. Townsend: None. P. Segers: None. P. Zamani: None.
- © 2016 by American Heart Association, Inc.