CORRELATION OF CIRCULATING VONWILLEBRAND-FACTOR LEVELS WITH CARDIOVASCULAR HEMODYNAMICS

Background. Valvular heart disease is associated with a decreased platelet circulating time and a thrombotic tendency. The possibility that these events are related to changes in von Willebrand factor (vWF), a multimeric glycoprotein released from endothelial cells and platelets that mediates platelet adhesion to the vascular subendothelium, has not been examined. Methods and Results. We measured the vWF antigen (vWF:Ag) concentration in 43 patients undergoing cardiac catheterization for the evaluation of mitral (n = 17) or aortic (n = 10) stenosis or nonvalvular heart disease (n = 16). Mean vWF:Ag concentration was significantly higher in patients with mitral stenosis than in those without (212 +/- 84 versus 150 +/- 79 units/dl, p < 0.02); this elevation was associated with a significant elevation of pulmonary vascular resistance (PVR) in the patients with mitral stenosis (186 +/- 49 versus 133 +/- 81 dynes-sec-cm-5, p < 0.02). The vWF:Ag levels in the entire group of patients (regardless of the presence or type of valvular disease) varied directly with PVR (r = 0.72, p < 0.0001) and with pulmonary artery pressure (r = 0.60, p < 0.0001) and inversely with cardiac output (r = 0.64, p < 0.0001). Changes in PVR, pulmonary artery pressure, or cardiac output could not be correlated with circulating levels of fibrinogen or beta-thromboglobulin, which may be released from activated platelets, nor with the endothelial cell product tissue plasminogen activator. Conclusions. The association of high vWF:Ag levels with increased PVR and decreased cardiac output in patients both with and without mitral stenosis suggests a hemodynamically induced increase in the endothelial release of vWF, which might contribute to a thrombotic tendency in these patients.