Disturbance of peripheral microvascular fluid permeability by the onset of atrioventricular asynchrony in patients with programmable pacemakers.

BACKGROUND In vitro and in vivo evidence suggests that atrial natriuretic peptide can enhance fluid flux from intravascular to extravascular compartments. The relevance of this to human pathophysiology remains unclear. OBJECTIVES To determine whether a central haemodynamic change associated with increased plasma concentrations of atrial natriuretic peptide produces detectable change in the capillary filtration coefficient in a peripheral microvascular bed. PATIENTS 12 patients with programmable dual chamber permanent pacemakers. METHODS Calf capillary filtration coefficient (using a modified plethysmographic technique) and plasma atrial natriuretic peptide concentrations were measured during atrioventricular synchronous and ventricular pacing. RESULTS Atrioventricular asynchrony was associated with higher mean (SD) concentrations of atrial natriuretic peptide (231.9 (123.1) v 53.5 (38.8) pg/ml) and an increased mean (SD) calf capillary filtration coefficient (4.2 (1.1) v 3.6 (1.1) ml/min.mm Hg.100 ml x 10(-3)), but there was no correlation between the magnitude of the change in these variables in individual patients. CONCLUSIONS The peripheral capillary filtration coefficient may change in response to altered central haemodynamics. Atrial natriuretic peptide remains one potential candidate mechanism, but other factors are also likely to be involved.