Dose-dependent benefit of nitroglycerin on microcirculation of patients with severe heart failure.

INTRODUCTION: Microcirculatory abnormalities are frequently observed in patients with severe heart failure and correlate to worse outcomes. We tested the hypothesis that nitroglycerin dose-dependently improves perfusion in severe heart failure and that this could be monitored by measuring central-peripheral temperature gradient and with Sidestream Dark Field imaging of the sublingual mucosa.
METHODS: A dose-response study was performed in 17 patients with cardiogenic shock (n = 9) or end-stage chronic heart failure (n = 8) admitted to Erasmus University Medical Center. We did hemodynamic measurements at baseline and during increasing infusion rates of nitroglycerin (up to a maximum dose of 133 microg min(-1)). As parameters of tissue perfusion, we measured central-peripheral temperature gradient (delta-T) and sublingual perfused capillary density (PCD).
RESULTS: Nitroglycerin dose-dependently decreased mean arterial pressure (p < 0.001) and cardiac filling pressures (both central venous pressure (CVP) and pulmonary capillary wedge pressure: p < 0.001). It increased cardiac index (p = 0.01). Nitroglycerin decreased delta-T (p < 0.001) and increased sublingual PCD (p < 0.001). Significant changes in delta-T and PCD occurred earlier, i.e., at a lower doses of NTG, than changes in global hemodynamics. Macrohemodynamic and microcirculatory responses to nitroglycerin infusion were consistent in patients with either cardiogenic shock or end-stage chronic heart failure. Changes in microcirculatory parameters occurred independently of changes in cardiac index.
CONCLUSIONS: Nitroglycerin dose-dependently increases tissue perfusion in patients with severe heart failure, as observed by a decrease in central-peripheral temperature gradient and an increase in sublingual perfused capillary density.