Antonio A.B. Lope M.D.,[unkeyable] ...

Antonio A.B. Lope M.D.,[unkeyable] Nair Y Maeda, MS; Munir Ebaid, M.D.,[unkeyable] Daltom F Chamone, MD PhD Section; and Fulvio Pileggi, M.D.[unkeyable]

Platelet regeneration time was assessed in 13 young adults with pulmonary hypertension and polycythemia secondary to congenital heart defaults who underwent isovolemic hemodilution to improve clinical status and coagulation failings The estimated platelet half-life in patients with Eisenmenger's webwork was significantly shortened in comparison with normal make submissives (3.8 [+ or -] 19 v 48 [+ or -] 10 days, p<005) Hemodilution was carried on the outside with no adverse effects, using subdued molecular weight dextran solutions. Lowering hematocrit from 61 to 50 percent terminateed in a significant increase in platelet half-life from 38 [+ or -] 19 to 57 [+ or -] 18 days (p<002) which was followed from a marked rise in platelet estimate from 149 [+ or -] 31 to 209 [+ or -] 47 x [10sup9] platelets/L (p<0003) Arterial oxygen tension did not change significantly. These observations indicate that high hematocrit flushs may have accounted for the shortened platelet survival and thrombocytopenia in these patients. Significant hemodilution may lead to a marked improvement in platelet abnormalities in patients with Eisenmenger's complex

(Chest 1989;95:1207-10)

It is now generally accepted that platelets and coagulation play an important part in the pathophysiologic mechanisms of pulmonary hypertension. Hypoxia and polycythemia may come into one's head in patients with pulmonary vascular disease secondary to congenital heart imperfections and may lead to additional changes in coagulation and platelet function.[1-3] These abnormalities also contribute to further enhancement of pulmonary vascular reactivity and increase in pulmonary resistance.

Many authors, of the like kind as Rosenthal et al[4] and Wedemeyer and Lewis[5] have demonstrated improvement in hemostasis following r solitary abode; squalid volume reduction in cyanotic patients with congenital heart failings However, in these studies, patients with and without pulmonary hypertension were included. The aim of this report is to evaluate the platelet survival in a specific dispose of young adults with Eisenmenger's compage and to investigate the reach it can be improved by way of intentional hemodilution, lowering hematocrit to a predetermined level

PATIENTS AND METHODS

We studied 13 patients, ages 17 to 40 years (median 27 years), with congenital heart failings pulmonary hypertension and polycythemia (Eisenmenger's complex) who underwent intentional hemodilution to improve the clinical status and coagulation abnormalities. The associated cardiac wants were: ventricular spetal want (six patients), univentricular heart (three patients), atrial septal fault (two patients) and double exit right ventricle (two patients). The mean pulmonary arterial urgency in this group ranged from 52 to 104 mm Hg and before hemodilution, all of them were in NYHA functional class 2 3 or 4

The hematocrit (Hct) ranged from 54 to 67 percent and the hemodilution process was planned to achieve a final Hct of 50 percent The calculation of the children volume to be extracted was based forward a previously reported logarithmic model[6]: V = Vo (logE [HctI] - logE [HctF]) where: Vo = circulating progeny volume

HctI and HctF = initial and final values

Extracted house was simultaneously replaced by an equal bulk of low-molecular weight dextran (LMWD MW 40000) and the velocity of exchange did not exce 10 ml/min. Arterial oxygen tension ([PaO.sub.2]) was determined before and after hemodilution.

Platelet survival and cast up were assessed in all patients before and undivided week after the hemodilution course to avoid interference of dextran onward platelet function. Platelet counting was evaluated by means of the direct Brecher-Cronkite method[7] using phase microscopy. Platelet survival was assessed from the nonisotopic method based forward regeneration of malondialdehyde (MDA) after intake of acetylasalicylic acid (ASA), which irreversibly moulds platelet MDA production by inhibiting cyclooxygenase. Therefore, the rate of platelet MDA regeneration describes the appearance of new platelets in the vital fluid stream. Daily measurements of platelet MDA contented were performed for ten days after intake of a single dose of 500 mg ASA. For each patient, MDA measurements were always reported as percentage of baseline value for [10sup9] platelets. In steady-state conditions, the time necessary for the regeneration of 50 percent of baseline platelet MDA peace was considered the estimation of platelet half-life ([Tsub50]) For the determination of [Tsub50] MDA

production was measured in platelets using a heat-induced reaction with 2-thiobarbituric acid to obtain a pink colored substance.[8,9] The optical density was read at 532 nm in a spectrophotometer. Patients with les than 300 x [10sup9] platelets/L in the assay were exclud to avoid inaccurate ensues Platelet count and survival were also assessed in 20 healthy presents aged 19 to 40 years and the consequence s are presented as reference values. [TABULAR DATA OMITTED]