Impact of nitroglycerin-induced vasodilation on stroke volume and diuretic response in acute heart failure: A protocol for a mechanistic trial.

Background: Acute heart failure is a clinical syndrome characterized by cardiac dysfunction and neurohumoral activation, encompassing complex underlying pathophysiology which may vary across phenotypes. Nitroglycerine is a nitrate donor with vasodilatory effects on both venous capacitance vessels and arterial resistance vessels in higher doses, typically used with the aim of reducing congestion, preload, and afterload. A limited number of studies have proposed that nitroglycerin could promote diuresis and natriuresis. However, the exact hemodynamic effects of nitroglycerin remain uncertain in the clinical setting of acute decompensated heart failure. We hypothesize that intravenous nitroglycerin induces a significant increase in stroke volume and urinary output while lowering cardiac filling pressures.

Methods: This will be a prospective single-center interventional clinical study of 21 patients hospitalized with a diagnosis of AHF. Patients are examined before and after administration of intravenous nitroglycerin. To characterize hemodynamic phenotypes of AHF, continuous estimates of stroke volume will be obtained, and total blood volume estimated. Vital signs and estimates of peripheral perfusion will be recorded continuously. Measures of cardiac function, renal function, volume status, and autonomic function will be assessed sequentially.

Conclusion: This study will assess the acute effects of vasodilation on stroke volume and urinary output in hospitalized patients with AHF. Furthermore, characterizing the hemodynamic profile of the patient prior to vasodilation may help explore which patients will benefit from vasodilation.