Transesophageal Echocardiography of Pulmonary Thrombus Causing Complete Left Pulmonary Artery Occlusion

Abstract

A 36-yr-old female patient was referred to our institution for management of a pulmonary embolism (PE) associated with respiratory failure. Her history was significant for an uncomplicated partial hysterectomy 6 months previously. One month later she presented to an outside hospital with dyspnea and chest pain. Computed tomography of the chest demonstrated a massive PE occluding the left pulmonary artery (LPA). Transthoracic echocardiography (TTE) revealed a moderately enlarged right ventricle (RV) with moderate decrease in contractility and an estimated RV systolic pressure of 58 mm Hg. Left ventricular (LV) function was normal. Her preoperative angiogram at our institution demonstrated complete occlusion of the LPA at its origin. The patient underwent pulmonary thromboendarterectomy with cardiopulmonary bypass (CPB). Intraoperatively, the entire LPA was found to be occluded with organized thrombus that was completely removed. Intraoperative pre-CPB transesophageal echocardiography (TEE) examination revealed signs of combined volume and pressure overload of the RV and moderate to severe RV dysfunction. The right atrium was massively enlarged and the interatrial septum was severely curved towards the left during systole and diastole. The interventricular septum displayed diastolic septal flattening (D-shaped ventricle). The LV function was normal. The modified mid-esophageal ascending aortic short axis (ME asc aortic SAX) view demonstrated a total occlusion of the LPA (Fig. 1) (video loop available at www.anesthesia-analgesia.org). The upper esophageal aortic arch short axis (UE aortic arch SAX) view further defined the contours and echogenic nature of the thrombus (Fig. 2). The post-CPB TEE examination confirmed a patent LPA. The postoperative ventilation/perfusion scan indicated differential perfusion in the left lung of only 3%. On the eleventh postoperative day, repeat TTE revealed a severely enlarged RV with global decrease in contractility with an estimated RV systolic pressure of 55 mm Hg. The LV function was normal. These presented images display thrombus in the LPA, a structure usually difficult to image secondary to interposition of left bronchus between the esophagus (TEE probe) and the LPA (1,2). Standard TEE imaging of the PA includes the UE aortic arch SAX view and the ME asc aortic SAX view, and should be complemented by evaluation for the presence of RV dysfunction and increased PA pressures in patients with suspected PE (1).Figure 1.: Modified mid-esophageal ascending aortic short axis view (probe tip depth: 30–40 cm from incisors) with the probe turned to the left to better visualize the pulmonary artery (PA) shows the pulmonic valve and the main PA (MPA). The left PA (LPA) arises on the right from the MPA. A massive thrombus totally occluding the LPA can be appreciated. Ao, descending thoracic aorta.Figure 2.: Upper-esophageal aortic arch short axis view (probe tip depth: 20–25 cm from incisors) demonstrates the pulmonic valve and the main pulmonary artery (MPA). A large thrombus can be appreciated in the region where the left pulmonary artery arises from the MPA (arrow). AoA, aortic arch.