Summary
The fibrinolytic system was investigated in 120 patients with spontaneous or recurrent
deep vein thrombosis (DVT) without any known organic disease able to explain by itself
the occurrence of a thrombosis and without any known defect of antithrombin III, Heparin
Cofactor II, Protein C, or Protein S. The assays included: Euglobulin fibrinolytic
activity (EFA), tissue-type plasminogen activator related antigen (t-PA-Ag) and plasminogen
activator inhibitor activity (PA inhibitor), which were measured before and after
10 min of venous occlusion (V. O.). On the basis of the results, the patients could
be classified in 3 groups:good responders with an at least two-fold increase of EFA
after venous occlusion (n = 76), poor responders with a lesser increase of EFA due
to deficient release of t-PA (n = 12), and poor responders with a normal t-PA release
but an increased level of PA-Inhibitor (n = 32).
The poor responders due to deficient t-PA release (10% of total) had a higher incidence
of recurrence of deep vein thrombosis, than the other groups (p <0.01). An overall
correlation was found between the level of PA-Inhibitor activity and the triglyceride
level (r = 0.40, p <0.01), suggesting that these elevations may be due to a common
cause, at least in some of the patients.
It is concluded that a poor fibrinolytic response to venous occlusion occurs in 35
percent of DVT patients. Poor responders however fall into two categories, one fourth
with deficient t-PA release who have a high risk for recurrent venous thrombosis,
and three fourth with increased PA-Inhibitor levels which may be associated with underlying
diseases also causing hypertriglyceridemia. Further elucidation of the correlation
between recurrent venous thrombosis and deficient fibrinolysis is expected to result
in more specific and adequate treatment and prevention of DVT.
Keywords
Tissue type plasminogen activator (t-PA) - PA inhibitor - Deep venous thrombosis -
Fibrinolysis
