Abstract 11091: Excess Circulating B-Type Natriuretic Peptide (BNP): A Previously Unsuspected Cause of Severe Orthostatic Hypotension
Introduction: The pathophysiology of orthostatic hypotension (OH) is multifactorial, but may be generally characterized by the presence of relative or absolute systemic volume depletion and/or inadequate vasoconstriction that undermine hemodynamic compensation to movement to upright posture. In this setting (i.e. euvolemic or hypovolemic OH patients (pts) with normal cardiac systolic function), increased circulating levels of B-type natriuretic peptide (BNP) and its amino-terminal cleavage fragment (NT-proBNP) would not be expected. Specifically, while the diuretic and vaso-relaxant properties of BNP could contribute to OH, BNP is primarily secreted from left ventricular (LV) myocytes in response to increased myocardial wall stress in association with volume overload conditions.
Methods: We describe findings in 7 pts who presented with severe OH that required aggressive volume resuscitation, but who nonetheless exhibited unexpectedly elevated concentrations of plasma BNP/NT-proBNP. All pts underwent thorough endocrine and echocardiographic evaluations and right heart catheterization.
Results: On initial presentation with OH, NT-proBNP concentrations (pg/ml) in the 7 pts were 2570, 3480, 4110, 6880, 2490, 6680 and 8860 (normal value <300). All patients had normal LV systolic and diastolic function except for mild LVH in one case. Right heart catheterizations were consistent with euvolemia or hypovolemia with appropriate response to intra-catheterization volume resuscitation. Follow-up ranged from 1 to 10 months with NT-proBNP monitoring. Requirement for volume repletion therapy closely tracked alterations of NT-BNP concentrations.
Conclusion: In select, but as yet not fully understood circumstances, unexpectedly elevated levels of BNP / NT-proBNP in the setting of euvolemia or hypovolemia may provide a previously unsuspected basis for severe symptomatic OH.
- © 2013 by American Heart Association, Inc.