[Thrombosis of a cardiopulmonary bypass circuit despite recommended hypocoagulation with danaparoid during the acute phase of type II heparin-induced thrombocytopenia]. / Thrombose d'un circuit de circulation extracorporelle sous danaparoïde sodique à la phase aiguë d'une thrombopénie induite par l'héparine de type II en dépit d'une hypocoagulation recommandée.

ABSTRACT

A 36-year-old patient was admitted to our hospital with ischaemic stroke. The initial assessment allowed the diagnosis of an antiphospholipid syndrome (APS) and an intracardiac mass suggestive of a heart tumour. The patient was treated with unfractionated heparin. Type II heparin-induced thrombopenia (HIT) was diagnosed on the 18th day of therapy. Given the risk of stroke recurrence it was decided to remove the cardiac tumour surgically. Cardiopulmonary bypass (CPB) was performed using danaparoid in a state of deep hypothermia, in accordance with the well-established protocol in use in our department. As the CPB and surgical procedure came to an end a massive thrombus began forming in the circuit, requiring immediate displacement of the CPB cannulae. The anti-Xa activity level obtained had been considered effective at an estimated 1.20 IU/ml, although, the level recommended by Magnani is between 1.50 and 2.0 IU/ml. There was no clinical consequence and postoperative recovery was uneventful. The discrepancy between the satisfactory level of anti-Xa activity and the thrombus formation in the CPB circuit raises the issue of the diversity of published anticoagulation protocols, the difficulty to extrapolate within a surgical team, the need for intensive laboratory monitoring within a narrow therapeutic range, as well as the patient profiles variability with concurrent disorders complicating their clinical management.