Intracoronary Macrothrombus Formation During Percutaneous Coronary Intervention Despite Optimal Activated Clotting Time Using Bivalirudin

Hemostasis based on a novel 'two-path unifying theory' and classification of hemostatic disorders

: Hemostasis is the most important protective mechanism for human survival following harmful vascular damage caused by internal disease or external injury. Physiological mechanism of hemostasis is partially understood. Hemostasis can be initiated by either intravascular injury or external bodily injury involving two different levels of damage [i.e., limited to the endothelium or combined with extravascular tissue (EVT)]. In intravascular injury, traumatic damage limited to local endothelium typically is of no consequence, but disease-induced endothelial damage associated with systemic endothelial injury seen in sepsis and other critical illnesses could cause generalized 'endotheliopathy'. It triggers no bleeding but promotes serious endothelial molecular response. If intravascular local trauma extends beyond the endothelium and into EVT, it causes intravascular 'bleeding' and initiate 'clotting' via normal hemostasis. In external bodily injury, local traumatic damage always extends to the endothelium and EVT, and triggers 'bleeding' and 'clotting'. Systemic endotheliopathy activates only unusually large von Willebrand factor multimers (ULVWF) path and mediates 'microthrombogenesis', producing 'microthrombi' strings. This partial activation of hemostasis with ULVWF path leads to vascular microthrombotic disease. But localized traumatic injury extending to the endothelium and EVT activates both ULVWF and tissue factor paths. Combined activation of ULVWF and tissue factor paths provides normal hemostasis in external bodily injury, but causes 'macrothrombus' formation in intravascular injury. This 'two-path unifying theory' concept succinctly elucidates simplified nature of hemostasis in intravascular and external bodily injuries. It also clarifies different pathogenesis of every hemorrhagic disease and thrombotic disorder related to internal vascular disease and external vascular injury.

Optical Coherence Tomographic Evaluation of Hyperacute Bivalirudin-Induced Coronary Stent Thrombosis

Thrombus formation after stent deployment has been linked to the use of heparin and of antithrombotic agents, such as bivalirudin, during percutaneous coronary intervention. Fluoroscopy has been used to identify stent thrombosis, typically after patients become symptomatic. We describe our use of optical coherence tomography to diagnose and evaluate intraprocedural stent thrombosis in a 68-year-old man who was given bivalirudin just before a percutaneous coronary procedure. This imaging method enabled immediate therapeutic intervention.

Extensive fatal intracoronary thrombosis during percutaneous coronary intervention with bivalirudin

The authors describe 2 cases of extensive intracoronary thrombus formation leading to acute closure of the left main where bivalirudin (Angiomax) was used as the anticoagulant during percutaneous coronary intervention leading to mortality. Both cases had similarity in the cascade of complications of coronary dissection leading to slow flow and prolonged procedure time with compromise of antegrade flow in the coronary artery and a final catastrophic development of extensive intracoronary thrombosis extending into the left main and nonintervened vessel (left anterior descending or circumflex) followed by ventricular fibrillation and death. Bivalirudin has reversible anticoagulant pharmacodynamics because the bivalirudin molecule is cleaved by the thrombin molecule. In situations when the antegrade flow is compromised, delivery of fresh circulating bivalirudin to replenish the catalysis of bivalirudin by thrombin is diminished, allowing thrombin activity to regenerate, thereby creating a prothrombotic milieu in these coronary segments. This can lead to extensive intracoronary thrombus formation in situations of slow flow precipitated by coronary dissection and prolonged dwell time with intracoronary hardware (wires, balloons, and stents). Interventionalists should be aware of the potential risk of this fatal complication and should be proactive in recognizing the scenarios where this is likely to occur. In such anticipated circumstances, the interventionalist may judiciously switch the anticoagulant to heparin and/or use additional glycoprotein IIb/IIIa inhibitor because freshly formed intracoronary thrombus is susceptible to lysis by glycoprotein IIb/IIIa inhibitors.