Influence of Phlebotomies on Arterial Hemodynamic Parameters in Polycythemia Vera Patients.

Thrombosis is the major complication of Polycythemia Vera (PV) and the main cause of morbidity and mortality. Hypercoagulability is principally secondary to hypervisosity of the whole blood. Blood viscosity is an exponential function of the hematocrit, and red cell aggregation increases in high hematocrit level, creating the potential for vascular stasis. 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. Such an effective therapy may have some effect on the arterial compliance in PV patients; nevertheless, to the best of or knowledge, the influence of phlebotomies on arterial hemodynamic parameters has not be studied in PV patients. In this study we estimated the influence of phlebotomies on large arteries (C1) and small arteries compliance (C2) in PV patients by non invasive method. Hemodynamic parameters were studied by Pulse Wave Analysis using the HDI-Pulse Wave CR2000 (Minneapolis MN, USA) immediatly before and after venesection (300–500cc of blood) (short effect of phlebotomy) and repeated within 3 months, after the hematocrit has been reduced to below 45% in male and 42% in female (long effect). Seventen PV (10 males) patients diagnosed according to the PVSG criterias have been included. 37 phlebotomies were performed with analysis of short effect (for 3 patients phlebotomy was performed 5 times, for one patient- 4 times, for five-twice, and for eight- once). There were 10 mesurements of long time effect of the phlebotomy. The median age of the patients was 66 years (range 48–82). The median hematocrit level was 49.3% (range 46.5–62) before phlebotomy. 47 measurements of the arterial compliance were performed (two patients visited 6 times, one- five times, one-4 times, three- 3 times, seven- twicely, and 3 patients once). The mean large artery compliance (C1) before phlebotomy was 12.0 ml/mmHg x 10 (range 4.5–28.6), in 36 measurements these parameters were normal for gender and age adjustment, and in 11 they were borderline. Immediately after phlebotomy the mean large artery compliance was 12.6 ml/mmHg x 10 (range 5.2–20.1). 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- not statistically significant). In 47 measurements of C2 before phlebotomy, 22 were within normal range, 6 borderline, and 19 pathological.. In 37, C2 measurements after phlebotomy, 21 were within normal range, 4 borderline and 12 pathological. The long term effect analysis demonstrates that the mean C1 after hematocrit normalization was13.8 mg/mmHg x 10 (delta 1.8- not statistically significant). The mean C2 after hematocrit normalization was 4.76 mg/mmHg x 10 (delta 0.36- not significant). In conclusion, phlebotomy has no significantly short or long term influence on large and small artery compliance in PV patients.