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[1] 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 (C1) 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 (300–500 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.