The dynamic changes of LDH isoenzyme 3 and D-dimer following pulmonary thromboembolism in canine

To investigate the time course of changes of lactic acid dehydrogenase (LDH), LDH isoenzymes and D-dimer levels following acute pulmonary thromboembolism (PTE).

Eighteen dogs were randomly divided into three groups. Acute PTE was induced by injection of preformed blood clots into pulmonary artery through femoral vein. Thrombin and human fibrinogen were delivered into blood clots in embolism group I. Only thrombin was delivered into blood clots in embolism group II. The control group received normal saline and human fibrinogen in the same manner. Series of blood samples were collected pre-embolism and post-embolism. LDH isoenzymes proportion and D-dimer levels were measured.

At 30 min, 1 h, 2 h, 4 h, 24 h post-embolism, the plasma D-dimer levels from embolism group I were significantly higher than pre-embolism and those from control group at the same intervals (p<0.05). The peak appeared at 2 h post-embolism (2.336+/-0.326 vs. 0.016+/-0.013, p<0.05). At 4 h, 24 h and 48 h post-embolism, total serum LDH activity and LDH-3 proportion from two embolism groups were significantly higher than pre-embolism (p<0.05). The peak of LDH-3 proportion in two embolism groups both appeared at 24 h post-embolism (0.225+/-0.021 vs. 0.108+/-0.030, 0.214+/-0.011 vs. 0.096+/-0.031, respectively. p<0.05).

The LDH-3 and D-dimer levels were changed dynamically with a relative specificity manner during the course of acute massive PTE. Combination the D-dimer assay with LDH-3 may have a potential value in diagnosing acute massive PTE.