الفهرس 
acknowledgmentOnly 14 pages are availabe for public view
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Abstract
Deep vein thrombosis (DVT) and pulmonary embolism (PE)
remain a genuine threat to many patients . The presentation of venous thromboembolism may be abrupt or insidious and institution of appropriate therapy is paramount but can be accomplished only if the clinician has a working knowledge of the disease and its implication. Misdiagnosis occasionally is fatal(194)
The development of sensitive methods for the diagnosis of deep venous thrombosis and pulmonary emboli has yield a greater insight into the epidemiology of thromboembolic diseases^ 15). Several notable risk factors, e.g age, history of previous venous thrombosis or pulmonary emboli and infection have been identified arid evaluated in various clinical situations (215). Operations and trauma are two important predisposing conditions. Prophylaxis of thromboembolism is now established in surgical patients and has considerably decreased the frequency of these complications (215).
Thrombosis is frequently associated with impairment of fibrinolysis in both acquired and hereditary disorders(237-240). Fibrinogen degradation products (FDPs) levels usually are significantly increased in the presence of pulmonary embolism. This phenomenon often is transitory and apparently is the results
of lysis of newly formed fibrin rather than dissolution of an embolus. (215) Specific tests for fragments (E& DD) dimer may be more definitive than standard tests for FDPs in the diagnosis of pulmonary embolism and DVT 215).
In view of this, it was decided to study the correlation between clinical parameter , the level of alpha2-antiplasmin (alpha2-AP) and plasminogen activator (t-PA) (it was estimated in the plasma of all the same studied patients in another study in the same laboratory in press), Fibrinogen degradation products (DD &E fragments ) and some laboratory tests as (Bleeding time (B.T), coagulation time (C.T) and prothrombin time (P.T) , and the incidence of deep venous thrombosis in silent cases in the post¬operative group in an attempt , may help to identify patients at risk for pulmonary emboli.
The present study was carried out on 35 patients of which twenty patients had de’novo DVT, fifteen patients with post operative DVT, in addition to fifteen healthy subjects of matched age and socioeconomic status as control , which were free from any occlusive vascular disease (venous or arterial). All patients chosen were free from diabetes, heart, or any metabolic diseases.
The results of the present study revealed that the values of B.T., C.T, and PT in the blood of all studied patients were amounted with those of normal control, whereby , these
parameters do not have any significant diagnostic value for thrombosis in individual patients .
Otherwise , the data of FDPs (DD & E fragments ) exhibit a significant increase in the sera of de novo deep venous thrombosis group. This finding is consistent with several studies which reported that FDPs levels usually are significantly increased in the presence of pulmonary embolism and DVT( 193,195). Further more, extremely sensitive methods for the measurement of fibrinopeptides and specific FDPs, such as the (DD dimer & DDE trimer), are being evaluated as indices of disseminated intravascular coagulations (DIC), and as markers of more subtle activities of coagulations in vivo (241).
The present data revealed that the studied patients with deep venous thrombosis either de novo or post operative had a striking significant decrease in the level of alpha2-AP and t-PA when compared with those of control group. These findings are in agreement with many investigations (232,233) which showed that patients with low t-PA activity in their blood are at increased risk of DVT postoperatively (232,233) and of recurrent spontaneous DVT(234). At the same time Rakoczi ef al (193) found that the estimation of alpha2-antiplasmin level preoperatively showed significant decrease in the blood of patients who subsequently developed deep vein thrombosis than those who did not (193).
Recent studies in patients with idiopathic deep venous thrombosis have shown that deficient fibrinolysis is increasingly diagnosed as the underlying mechanism for the propensity for the development of abnormal thrombosis (234).
In principle, defective fibrinolysis might be due either to (1)-a decreased synthesis of vessel wall tissue plasminogen activator (t-PA) or a defective release of activators or both, or (2)-inactivation of t-PA by inhibitor (236).
At the same time the significant decrease in the level of alpha2- antiplasmin in the blood of patients with DVT in this study was confirmed by several investigators^14^, 151,210,193,195) who reported that ihe concentrations of alpha2-PI in the circulating blood is readily reduced when plasminogen is activated under thrombolytic therapy or in disseminated intravascular coagulations (DIC)(l43) or in DVT patients(193)t because alpha2 PI rapidly inhibits plasmin evolved by forming a complex which is
removed from the circulating blood by the reticulo-endothelial system(214,224).
In addition to the rapid inactivation of plasmin alpha2-AP interfers with adsorption of plasminogen to fibrin, resulting in an efficient inhibition of fibrinolysis . Furthermore, alpha2-AP is cross-linked to fibrin when blood is clotted thereby making the fibrin clot less susceptible to lysis by plasmin (142).
In conclusion , the present findings confirm and extend the observations that prediction of deep vein thrombosis from relatively simple sets of clinical presentation and assays for individual components of the fibrinolytic enzyme system, including t-PA , alpha2-AP FDPs (DD & E fragments), have been perfected (242). The applications of these parameters together might help to identify patients at risk for post operative thrombosis.
Furthermore, the determination of aforementioned parame¬ters in the blood may be used in the diagnosis of DVT specially in silent and equivocal cases. Moreover, it is important in detection of recurrent DVT and recurrent pulmonanry embolism.