Acute right ventricular dilatation: a new helical CT sign of massive pulmonary embolism

Acute right heart failure is a principal cause of circulatory collapse and death in patients with massive pulmonary embolism (PE). The purpose of this study was to investigate if helical computed tomography (CT) could contribute to the assessment of the right ventricle (RV) in those with massive PE. Over an 8-month period 79 helical CT pulmonary angiograms were performed to investigate suspected PE. Emboli were demonstrated in 28 (35%) patients and seven (9%) were considered to have had a major thromboembolic event. The CT scans of all patients were evaluated using parameters derived in the axial plane (maximum minor axis RV and LV dimensions, RV:LV minor axis ratio and RV wall thickness). Acute right ventricular dilatation with an RV:LV ratio> 1.5:1 (range 1.6:1-2.3:1, mean 2:1) was found in all seven patients who had sustained major PE. In the remaining group of 21 with lesser degrees of embolism no patient had an RV:LV ratio > 1.1:1 (range 0.8-1.1, mean 1.0). To our knowledge, this CT sign has not been described before. CONCLUSION: Helical CT can identify acute RV dilatation in addition to making the primary diagnosis in patients with massive PE. This observation may help identify those at greatest risk of a second fatal event and facilitate therapeutic strategy.