A New Kid on the Block in POCUS: “LISA”

Transesophageal echocardiography (TTE) and computed tomography angiography (CTA) are methods of choice for definitive diagnosis and prognostic stratification of acute aortic syndromes (AAS).1 Point-of-care ultrasound (POCUS) has important applications in the initial workup of these patients in the emergency room (ER), ruling out other potential causes of chest pain and allowing a faster diagnosis,2 although conventional transthoracic echocardiographic acoustic windows do not allow for imaging of some segments of the thoracic aorta (TA), especially the descending TA (DTA). A 49-year-old man, with a 20-day history of dorsal and abdominal pain, shortness of breath (NYHA-III) and peripheral edema was admitted to the hospital ER. He had uncontrolled systemic hypertension and a history of smoking, without a family history of aortic diseases or sudden death. At admission, the patient was unstable hemodynamically, with clinical signs of biventricular heart failure. A TTE showed dilation of all cavities, severe biventricular systolic dysfunction, a giant (10.1cm) dissecting aneurysm (DA) of ascending aorta (AAo) (Fig.1-A, Video1), with a partially thrombosed false lumen extending to the supravalvular aortic region, causing geometric distortion of the aortic root and moderate-to-severe aortic regurgitation (Fig.1-B). The entry tear was nicely depicted in two-dimensional/threedimensional TTE from a right parasternal window (Figures 1-C,D, Video2), located in tubular AAo. The dissection extended to the descending thoracic aorta (DTA) and abdominal segments, with a large and highly pressurized false lumen. The posterior path of the dilated DTA in the thorax was easily accessible by ultrasound using a matrix probe, through a non-conventional left interscapular window, with good definition of intimal flap, spontaneous contrast and thrombus in the false lumen, in short-axis and longitudinal view (Figures 2 A, B, C, Video3), and nicely depicted by three-dimensional reconstructed images (Figure 2-D, Video4). These findings were confirmed by CTA, showing a giant Stanford type A DA (Figures 2-E-F). AAS are life-threatening conditions with high morbidity and mortality, especially when there is a delay in diagnosis and adequate treatment.3 POCUS as a first line approach for patients with suspected AAS in the ER can provide important data for a faster and more accurate diagnosis, detecting also signs of complications as pericardial effusion, pericardial tamponade, left and right ventricular dysfunction, acute aortic regurgitation, periaortic hematoma and hemothorax, supporting the need for urgent intervention. The DTA is not well visualized with conventional TTE windows, and a dorsal window is not currently cited as part of the routine investigation in the guidelines.4,5 We propose the use of a new echocardiographic window, the Left InterScapular Approach (LISA), for POCUS screening of patients with suspected AAS, even without pleural effusion. In cases where there is dilatation of DTA, due to its posterior path in the thorax, this new approach may provide images with great anatomic details, as exemplified in a case of a giant dissecting TA aneurysm, with very good correlation with CTA findings. It is the first description of this new window obtained by the LISA, and we strongly suggest that it may be incorporated in the initial workup of patients with suspected AAS as a non-invasive tool.