Detected residual venous thrombi and catheter-directed management of intermediate-risk pulmonary thromboembolism

Figures

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  Figure 1. A schematic presentation of the association between loss of pulmonary vasculature patency and rising pulmonary pressure. This low resistance vascular system can tolerate some 50% vascular obliteration by massive emboli without a significant increase in pulmonary pressure. But beyond this point, pulmonary pressure rises exponentially by even small additional embolic episodes (from A to B), with consequent hemodynamic instability (obstructive shock) and the development of pulseless electrical activity and death. Reducing RV afterload by catheter-directed interventions (embolectomy and/or thrombolysis) will move the hemodynamic status to the left along the declining curve (upper blue arrow from A to C), in a way that a repeated comparable embolic episode (dashed red arrows at the bottom) will be tolerable (lower blue arrow) and not associated with a life-threatening rise in pulmonary pressure. Compromised cardiopulmonary status related to other co-morbidities might also be associated with a much earlier rising slope of pulmonary pressure and lethality, generated by rather small emboli. [modified from Wood KE, Chest 2002 (3)].

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  Figure 2. A proposed algorithm showing the assessment and management of hemodynamically stable individuals with PE, focusing on intermediate-low-risk patents. This category is defined as evident Rt. ventricular compromise (RV dilatation, reduced RV systolic function, marked pulmonary hypertension, lack of vena cava collapse on inspiration) or as a high simplified PE score index (PESI), in the absence of rising troponin and/or pro-BNP (10). A mandatory duplex study in such patients should help identify those with retained above-knee large venous clots, susceptible to repeated potentially lethal thromboembolic events. Catheter-directed intervention (CDI) should be considered in this case, along with decisions regarding delaying ambulation.