A model of massive pulmonary embolism, development and characterization: The pre-clinical steps forward and details of the progress

Background: Massive pulmonary embolism (MPE) is in most cases an unpredictable, life-threatening lung injury. In order to test this shock and its natural sequence, MPE animal model was established. Based on previous models, discussed within the article framework, this model was designed to closely narrate clinical pulmonary embolism. Methods: MPE was induced by a single injection of minced radioactive blood thrombi into an internal jugular vein. Thrombi were prepared from the autologous blood of each animal. Using rabbit model allowed sampling and recording additional data necessary for better analysis. Clotting additives were used for rapid clot stabilization. Clot was stabilized at room temperature for one hour and separated into micro-emboli of comparable size prior to the intravenous injection. A radioactive tracer, I-125 labeled rabbit fibrinogen, was added into thrombi to measure dynamic lung thrombi-turnover. Results: Thrombolysis dynamic efficacy was characterized by presence of high statistical significant difference (P<0.001) found between released radioactive I-125 fibrin degradation products (FDPs) at 10 minutes and all others FDP time points until 60 minutes. Pulmonary thrombolysis was characterized by measuring residual radioactivity of the lungs at 10 and 60 minutes and was found statistically significant (P < 0.05) during the period of 50 minutes. For the purpose of model validation, systemic blood pressure, measured in carotid artery, significantly increased from the baseline point 47 mmHg to 80 mmHg at the first 10 minutes. Enormous mechanical thrombus injury of lung vasculature was depicted by MSB staining. Conclusions: This MPE model contains a set of important and original patho-physiological data mimicking the fundamental characteristics of this shock situation in humans, which enhances the understanding of MPE, and leads to better characterization of this critical clinical condition.