The E-wave propagation index (EPI): A novel echocardiographic parameter for prediction of left ventricular thrombus. Derivation from computational fluid dynamic modeling and validation on human subjects.

BACKGROUND: To describe the derivation and validation of a novel echocardiographic metric for prediction of left ventricle thrombus (LVT). METHODS: Computational fluid dynamic modeling using cardiac CT images was used to derive a novel echocardiography-based metric to predict the presence of LVT. We retrospectively reviewed 25 transthoracic echocardiograms showing definite LVT (LVT group). We then randomly selected 25 patients with LVEF ≥55% (Normal EF group) and 25 patients with severe cardiomyopathy (CMP) with LVEF ≤40% without evidence of LVT (CMP group). The E-wave Propagation Index (EPI) was measured as the E-wave velocity time-integral divided by the LV length. An EPI>1 indicates penetration of the mitral jet into the apex whereas an EPI<1 is indicative of incomplete apical washout. The mean EPI was compared between the three groups. Crude and adjusted odd ratios of EPI and LVT association were also measured. RESULTS: Mean EPI was highest for the normal EF group and lowest in the LVT group (1.7 vs. 0.8; p<0.0001). Mean EPI also differed significantly between LVT and CMP groups (0.8 vs. 1.2; p<0.0001). 88% of the LVT group had EPI <1.0 compared to only 20% of the CMP group (p<0.0001). Among the LVT and CMP groups, an EPI <1 increased the odd ratio of LVT by 53.7 times (95% CI: 6.9-416) controlling for LVEF and LV volume. CONCLUSIONS: The E-wave propagation index is a novel, easily-obtainable, echocardiographic metric to evaluate apical LV flow. An EPI of less than 1 is an independent predictor of LVT formation.

Effect of intravenous infusion of iodinated contrast media on the coronary blood flow in dogs.

BACKGROUND: Coronary computed tomography angiography (CCTA) is obtained using peripheral intravenous iodinated contrast agents (ICA) injection. There is continuing attempts to derive coronary physiological information like coronary blood flow (CBF) and/or fractional flow reserve from CCTA images. However, no data is available regarding the effect of peripheral intravenous injection of ICA on CBF. METHODS: A series of 4 experiments was performed using healthy mongrel dogs. All dogs underwent anesthesia and open thoracotomy with placement of ultrasound flowmeter to one of the coronary artery to provide real time absolute CBF measurements. Different infusion protocols of Isovue-370 and Visipaque-320 were injected into a peripheral vein. Similar doses of normal saline injection were performed to be used as controls. The effect of iodinated contrast media injection on absolute coronary blood flow was monitored and recorded. RESULTS: Injection of normal saline in the peripheral vein did not produce any significant increase in CBF. Peripheral intravenous injection of ICA resulted in a consistent increase of 40-73% in absolute CBF as recorded 5 minutes post-contrast administration. The contrast effect starts about 30 seconds and peaks at about 2 minutepost-contrast injection then slowly fades away in the following 10-15 min. The increase in the CBF was dose related. There was greater increase in the CBF to 50 ml infusion compared to 25 ml infusion of both Visipaque and Isovue. CONCLUSIONS: Peripheral venous administration of iodinated contrast-media in dogs results in a dose related, significant and prolonged increase in CBF.