Saddle Pulmonary Embolism with RV Strain
Updated: Mar 3, 2022
45 year old male with chest pain, tachypnea and shortness of breath • Xray of the Week
Figure 1. Name the important findings on this CT Scan.
Figure 2. CT Scan demonstrating saddle pulmonary embolism with RV strain. A: Saddle embolism (red arrow). Large bilateral emboli in right and left main pulmonary arteries (yellow and green arrows). B: RV strain with dilated RV, bowing of the interventricular septum to the left (blue arrows).
Figure 3. CT Scan demonstrating saddle pulmonary embolism with RV strain. A: Saddle embolism and dilated main pulmonary artery which is larger than the ascending aorta. B: RV strain with dilated RV, measuring larger than LV. C: Bowing of the interventricular septum to the left (yellow arrows).
Discussion:
Due to its high sensitivity and specificity, CT pulmonary angiography (CTPA) has become the imaging modality of choice in diagnosis of pulmonary embolism (PE) and has replaced VQ scanning within treatment algorithms (1,2). CTPA allows for a more accurate evaluation of clot size, extent of clot, underlying lung disease and evaluation of potential right ventricular (RV) strain. In addition, in up to 40% of patients CT demonstrates other pathology responsible for the patient's clinical picture (3-5). CT findings of PE include a central filling defect, vessel cut off, and rim sign. Multiple emboli are more common than solitary and lower lobes are usually more affected than upper lobes. Secondary findings on CT may include pulmonary infarct, hemorrhage, upper extremity DVT, hypoperfusion, atelectasis, and RV strain. An RV/LV ratio greater than one and leftward bowing of the ventricular septum are indicative of RV strain (5). A dilated RV is the most accurate and reproducible method of evaluating RV strain (5). Although, leftward bowing of the ventricular septum and inferior vena cava contrast reflux are also predictive of adverse outcomes (3). After myocardial infarction and stroke, pulmonary embolism is the 3rd leading cause of mortality due to cardiovascular disease. Mortality from RV failure is most often due to PE (4). Mortality rate is as high as 50-58% in those with hemodynamic instability and 8-15% in those without (4). The mainstay of treatment is cardiopulmonary support and anticoagulation; however, thrombolysis may play a role in cases with massive PE and cardiovascular compromise (6). Patients who can not be anticoagulated require an IVC filter.
References:
1. Ghaye B, Ghuysen A, Bruyere P-J, D’Orio V, Dondelinger RF. Can CT Pulmonary Angiography Allow Assessment of Severity and Prognosis in Patients Presenting with Pulmonary Embolism? What the Radiologist Needs to Know. RadioGraphics. 2006;26(1):23-39. doi:10.1148/rg.261055062
2. He H, Stein MW, Zalta B, Haramati LB. Computed tomography evaluation of right heart dysfunction in patients with acute pulmonary embolism. J Comput Assist Tomogr. 2006;30(2):262-266. doi:10.1097/00004728-200603000-00018
3. Kang DK, Thilo C, Schoepf UJ, et al. CT Signs of Right Ventricular Dysfunction: Prognostic Role in Acute Pulmonary Embolism. JACC: Cardiovascular Imaging. 2011;4(8):841-849. doi:10.1016/j.jcmg.2011.04.013
4. Kostadima E, Zakynthinos E. Pulmonary Embolism: Pathophysiology, Diagnosis, Treatment. Hellenic J Cardiol 48: 94-107, 2007
5. Kang DK, Ramos-Duran L, Schoepf UJ, et al. Reproducibility of CT Signs of Right Ventricular Dysfunction in Acute Pulmonary Embolism. American Journal of Roentgenology. 2010;194(6):1500-1506. doi:10.2214/AJR.09.3717
6. Araoz PA, Gotway MB, Harrington JR, et al. Pulmonary Embolism: Prognostic CT Findings. Radiology 2007;242:889-897 https://doi.org/10.1148/radiol.2423051441
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Neal Shah is a medical student at The Edward Via College of Osteopathic Medicine (VCOM)–Carolinas and intends on completing his residency within the field of radiology. Prior to medical school, he completed his undergraduate studies at the University of North Carolina at Chapel Hill where he majored in economics and chemistry. During his 4 years there he worked in UNC’s Biomedical Research Imaging Center where he helped develop formulations for iron-oxide nanoparticles used for MRI; it was here that his love for the field of radiology developed. He eventually wishes to also pursue his MBA and hopes to use it to help advance the field of medicine in terms of medical innovation.
Follow Neal Shah on Twitter @neal_shah17
Kevin M. Rice, MD is the president of Global Radiology CME
Dr. Rice is a radiologist with Renaissance Imaging Medical Associates. and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.
Follow Dr. Rice on Twitter @KevinRiceMD
