Platelet Aggregability in Patients with a VVI Pacemaker

Several studies have suggested an increased incidence of thromboembolic events in patients with VVI pacemaker (VVI patients); furthermore, other authors have demonstrated that a treatment with anticoagulants or antiplatelet drugs may be effective in reducing thromboembolic events, thus suggesting an increased formation of platelet thrombi in these patients. In this respect, platelet aggregability was investigated in ten VVI patients and ten age– and sex–matched subjects. β–thromboglobulin (β–Tg) and platelet factor 4 (PF4) plasma levels were determined as weJJ as platelet aggregation induced by ADP, collagen, epinephrine, and arachidonic acid. Plasma β–Tg JeveJs were increased in the patient group (86 ± 24 vs 24 ± 13 ng/mL; P < 0.001) in presence of normal PF4 values (14 ± 11 vs 13 ± 6 ng/mL; NS). Aggregation curves showed abnormal values of maximal amplitude, slope, and lag time. In particular, maximal amplitude was significantJy higher in VVI patients as compared with controls (ADP P < 0.01, collagen P < 0.001, adrenaline P < 0.01, arachidonic acid P < 0.05). These findings strongly suggest an increase of platelet activity in VVI patients.     

Effect of diatrizoate meglumine (Hypaque) on the perilymphatic oxygen tension

The effect of diatrizoate meglumine (Hypaque) upon the perilymphatic oxygenation has been investigated using the polarographic method in cats submitted to various conditions such as normoxia, apnea, hypercapnea and chronically reduced vascularization. The minimal changes of the perilymphatic PO₂ recorded after the injection of Hypaque permit to conclude that this drug has no practical effect upon the oxygenation of the perilymph.