Evaluation of Cardiac Thrombus Stability based on Contrast-Enhanced Echocardiography：Research Protocol and Preliminary Results

Abstract

Objective: This study attempted to test a new scoring system for evaluating the stability of cardiac thrombi using contrast-enhanced ultrasound (CEUS). Methods: We used human whole blood to make the thrombus model in vitro which were divided into 2 groups, the 1-hour (T1h) and 7-day (T7d) group. The T1h group was monitored for 1 hour continuously to observe for the formation of a new thrombus on the original thrombus base. Over time, changes in CEUS images and pathology and shear wave elastography (SWE) of thrombus were observed in theT1h and T7 groups. Twenty-eight adult patients diagnosed with a cardiac thrombus were selected and examined by transthoracic echocardiography (TTE) and CEUS. Thrombi were scored for substrate (Ts) and hardness (Th) based on the visualized degree of contrast penetration into the thrombus. The Ts and Th were statistically analyzed for thrombolytic time and the risk of embolism to other organs. Results: In vitro, pathology revealed a decreased pore structure; further, the average Young’s modulus of the thrombi over time indicated a progressive increase in hardness. Contrast-enhancing agents were able to enter a fresh, loose thrombus, but were not able to enter a chronic, stable thrombus. With increasing Ts and Th, thrombolytic time was prolonged, and the risk of embolism to other organs was increased. Conclusions: Our study results suggest that this new CEUS scoring system can evaluate the hardness of a cardiac thrombus and the quality of its underlying substrate; this allows for quantitative evaluation of thrombus stability.