Effect of simvastatin on micropulmonary red cell mass in patients with hyperlipoproteinemia

The purpose of this study was to compare the macrocirculatory and microcirc ulatory effects of simvastatin in hyperlipemic patients. In vitro measureme nts of lipoprotein levels and macrocirculatory hemorheology were complement ed by in vivo measurements of the pulmonary capillary red cell Volume (RCVp c) before and after 6 weeks of treatment with 40 mg of simvastatin daily in 30 male patients with hyperlipoproteinemia type IIa. RCVpc was assessed fr om the vascular component of the lung diffusing capacity for carbon monoxid e, using the modification of the Roughton-Forster's method. RCVpc was incre ased in patients (60.9 +/- 9 versus 40 +/- 9 ml in healthy controls) and it decreased to 47 +/- 6 ml after treatment (P = 5 x 10(-11)). The decreases in RCVpc correlated to concomitant decreases in peripheral hematocrit (R = 0.68) and serum total cholesterol (- 34% on average: R = 0.59). Membrane di ffusing capacity was normal in patients and nor affected by the therapy; su ggesting that increased RCVpc was due to increased micropulmonary hematocri t. Thus. it appears that viscosity in microcirculation is greatly increased in hyperlipemic patients and that simvastatin is able to normalize it. Sin ce microcirculatory conditions can only partly be inferred from in vitro me asurements the use of lung diffusional parameters was advocated, which enab le in vivo assessment of hemorheology in microcirculation. (C) 2001 Elsevie r Science Ireland Ltd. All rights reserved.