Low-dose nitroglycerin improves microcirculation in hospitalized patients with acute heart failure

Introduction

Impaired tissue perfusion is often observed in patients with acute heart failure. We tested whether low-dose nitroglycerin (NTG) improves microcirculatory blood flow in patients admitted for acute heart failure.

Methods

In 20 acute heart failure patients, NTG was given as intravenous infusion at a fixed dose of 33 μg/minute. Using sidestream dark field imaging, sublingual microvascular perfusion was evaluated before (T0, average of two baseline measurements) and 15 minutes after initiation of NTG (T1). In a subgroup of seven patients, NTG was stopped for 20 minutes, whereupon sidestream dark field measurements were repeated. Capillaries were defined as the microvessels with a diameter of <20 mm. The perfused capillary density (PCD) was determined as the parameter of tissue perfusion. Values are expressed as the median and interquartile range (P25; P75).

Results

The median age of the subjects was 60 (52; 73) years and 65% were male. Patients were in a stable condition before starting NTG. NTG decreased the central venous pressure (17 (13; 19) mmHg at T0 vs. 16 (13; 17) mmHg at T1, P = 0.03) and pulmonary capillary wedge pressure (23 (18; 31) mmHg at T0 vs. 19 (16; 25) mmHg at T1, P = 0.03). NTG increased PCD (10.7 (9.9; 12.5) mm/mm² at T0 vs. 12.4 (11.4; 13.6) mm/mm² at T1, P = 0.01). After cessation of NTG, PCD returned to baseline values (P = 0.04).

Conclusion

Low-dose NTG significantly reduces cardiac filling pressures and improves microvascular perfusion in patients admitted for acute heart failure.