C. Galigani

Allopurinol prevents ischaemia-dependent haemorheological changes

SummaryPre-treatment with allopurinol is able markedly to attenuate the deterioration in blood viscosity (BV) and whole blood filterability (WBF) that occurs after ischaemia during exercise. It also reduces the exercise-induced increase in serum oxidase activity, although this action is slightly less effective in peripheral obliterative arterial disease (POAD) patients.Conversely, allopurinol is completely ineffective in modifying haemorheological parameters in vitro, and it does not affect superoxide anion generation or enzyme release from neutrophils stimulated in vitro with formyl-methionyl-leucyl-phenylalanine (FMLP).It is suggested that allopurinol may attenuate changes in BV and WBF by affecting xanthine-oxidase-dependent free radical formation in tissues.

Effect on rheological and some peripheral haemodynamic parameters of defibrotide in POAD patients

Received 1.12.1986; Accepted 19.1.1987 by Editor T. DiPerri) In ten POAD patients, 800 mg. of Defibrotide (polideoxynucleotide extracted from mammalian lung, with antitrombotic and fibrinolytic activity) were infused i.v. Blood and plasma viscosity, haematocrit, blood filterability and fibrinogen concentration were controlled, in basal conditions and after one hour from the end of infusion. Haemodynamic parameters: rest flow, peak flow, time to peak flow, half time and total time of reactive hyperemia by means of strain gauge pletismography, were controlled at lower limbs before infusion and after 1 h., 2 h., 6 h., from the end of infusion. The present investigation showed an improvement of rheological parameters and a decrease of total time and half time of reactive hyperemia. These data demonstrate a rheological activity of Defibrotide as well as the fibrinolytic one.

CIRCADIAN VARIATION OF PLATELET AGGREGATION AND BLOOD RHEOLOGY

Many vascular pathologies have been reported to follow a diurnal rhythm (AMI, angina, stroke, sudden cardiac death, pulmonary thromboembolism) with a peak in the early morning. Aim of the study was to evaluate the existence of a diurnal rhythm of platelet aggregability and blood rheology. The study was carried out in 12 subjects; blood withdrawings were performed every 3 hour for 24 hours and in each blood sample platelet aggregation (on PRP and on washed platelets) and haemorheological parameters (blood viscosity, blood filterability, haematocrit and fibrinogen) were measured. Moreover systolic and diastolic blood pressure was recorded by dynamiC monitoring. The results show that a circadian rhythm of the above mentioned parameters does exists. Even if our data do not prove a strict correlation between these parameters and the incidence of the vascular pathology, it could be interesting to keep in mind the existence of a temporal parallelism when starting preventive therapy.

Hemodynamic and hemorheologic effects of iv dilevalol in hypertensive patients

The authors evaluated the effect of Dilevalol infusion on blood pressure, heart rate, central hemodynamics, and rheologic parameters in hospitalized inpatients affected with mild or moderate hypertension. After a dose-finding phase and a washout period of one week, 10 patients aged fifty to seventy-two-years (median 61.5) were given either a single dose of Dilevalol 60 mg or placebo, and seven days later they underwent the other treatment, according to a single-blind, crossover design. Central hemodynamic measurements were performed by means of M-mode echocardiography, and hemorheologic parameters were evaluated by means of strain-gauge plethysmography. The maximal increase in lower extremity flow at rest had been obtained with the infusion of 60 mg Dilevalol during dose-finding, and so this dose was chosen for the second part of the study. The infusion of Dilevalol significantly increased rest flow and decreased blood viscosity, but the changes in central, parameters were not considered clinically relevant, although statistically significant. Blood pressure decreased without significant changes in heart rate. Thus, the acute administration of Dilevalol reduced blood pressure, without affecting heart rate and central hemodynamics, confirming the vasodilating effect of the drug. A significant improvement was also shown on blood viscosity in these hypertensive patients.