Evaluation of arterial compliance in polycythemia vera patients: short and long-term influence of phlebotomy.

BACKGROUND Thrombosis is a major cause of morbidity and mortality in polycythemia vera. Hypercoagulability is principally due to hyperviscosity of the whole blood, an exponential function of the hematocrit. PV is also associated with endothelial dysfunction that can predispose to arterial disease. Reduction of the red cell mass to a safe level by phlebotomy is the first principle of therapy in PV. This therapy may have some effect on the arterial compliance in PV patients. OBJECTIVES To estimate the influence of phlebotomies on large artery (Cl) and small artery compliance (C2) in PV patients by using non-invasive methods. METHODS Short-term hemodynamic effects of phlebotomy were studied by pulse wave analysis using the HDI-Pulse Wave CR2000 (Minneapolis, MN, USA) before and immediately after venesection (350-500 ml of blood). We repeated the evaluation after 1 month to measure the long-term effects. RESULTS Seventeen PV patients were included in the study and 47 measurements of arterial compliance were performed: 37 for short-term effects and 10 for long-term effects. The mean large artery compliance (C1) before phlebotomy was 12.0 ml/mmHg x 10 (range 4.5-28.6), and 12.6 ml/mmHg x 10 (range 5.2-20.1) immediately after phlebotomy (NS). The mean small artery compliance (C2) before and immediately after phlebotomy were 4.4 mg/mmHg x 10 (range 1.2-14.3) and 5.5 mg/mmHg x 10 (range 1.2-15.6) respectively (delta C2-1.1, P < 0.001). No difference in these parameters could be demonstrated in the long-term arm. CONCLUSIONS Phlebotomy immediately improves arterial compliance in small vessels of PV patients, but this effect is short lived.