Advancements in 3D Transoesophageal Echocardiography (TOE) and Computed Tomography (CT) for Stroke Prevention in Left Atrial Appendage Occlusion Interventions

Figure 1. Different designs of percutaneous left atrial appendage devices. The Watchman and Watchman FLX devices extracted from Boston Scientific Corporation (USA) or its affiliates. The Amplatzer Cardiac Plug (ACP) and Amplatzer Amulet, from Abbot Corporation (USA). LAmbre device from Lifetech Scientific Corporation (China). Omega device from Eclipse Medical Corporation (Ireland). Penditure device from Medtronic Corporation (USA). AtriClip device from AtriCure Corporation (USA). LAAO: left atrial appendage occlusion; ACP: Amplatzer Cardiac Plug. Adapted with permission from Albors et al., 2024 [14].

Figure 2. Four different left atrium appendage morphologies as shown by CT. Adapted with permission from Dudziñska-Szczerba et al. [18].

Figure 3. Contraindications for placement of hybrid endocardial–epicardial devices in three patients. AO stands for aorta (a) Short-axis reconstructed CT image in a 47-year-old man shows circumferential pericardial calcification (arrows). (b) Axial CT image in a 43-year-old man shows a severe pectus excavatum deformity (arrow) with a Haller index score of 4.5. (c) Coronal reconstructed CT image in a 72-year-old man shows a venous bypass graft from the aorta to the obtuse marginal artery (straight arrow), which is situated directly adjacent to the LAA (curved arrow). CT: Computed tomography, LAA: Left atrial appendage. Adapted with permission from Rajjah et al. [16].

Figure 4. Cardiac CT measurement of the LAA ostium. Using 3D multiplanar reconstruction, cutting a double oblique plane across the coumadin ridge and the left circumflex artery (A,B) creates an en-face view of the ostium (C), determining its shape, perimeter (1), minimum (2) and maximum (3) diameters, as well as area (1). CT: Computed tomography; LAA: Left atrial appendage; 3D: Three dimensional.

Figure 5. (a) Measuring the landing zone for the Watchman device. The landing zone is positioned 10–20 mm within the LAA (dotted green line), starting from the Coumadin ridge. A line that connects the LAA near the left circumflex artery to the point 10–20 mm inward from the Coumadin ridge is then drawn (red line) to create an en-face view of the landing zone. The measurement of the dominant lobe length is taken from the plane of the landing zone to the tip of the dominant lobe (yellow line). LAA: Left atrial appendage. (b) Measuring the landing zone for the Amplatzer amulet device. The landing zone is positioned 10–12 mm inside the LAA orifice (dotted green line). The diameters are then determined using an en-face-view image, captured at this location, with measurements taken perpendicular to the LAA walls (red line). The LAA depth is assessed from the orifice (blue line) to the roof of the LAA (yellow line). LAA: Left atrial appendage.

Figure 6. Measurement of the angle between the transseptal puncture site and LAA ostium. (A–C) Simulated transseptal crossing in the coronal (A), sagittal (B), and axial (C) plane. (D) Virtual Angio view with a visualization of the angle between IAS and LAA. Green circle—LAA landing zone; Orange circle—LAA ostium; Hash sign—Projected septum contour with a simulated inferior/posterior puncture; Asterisk—Projected septum length and angle. LAA: Left atrial appendage. Adapted with permission from Nelles et al. [24].

Figure 7. Three-dimensionally printed model. (A) Anterior view, (B) posterior view; blue, tricuspid annulus; green, mitral annulus; pink, pulmonary veins; red, left atrial appendage; yellow, superior vena cava and inferior vena cava. Adapted with permission from Hozman et al. [25].

Figure 8. In vitro TSP simulation. LAA ostium and its axis are marked in yellow. (A,B) left anterior oblique (LAO) projection, (C,D) LAO with cranial angulation; (A,C) optimal sheath position (posterior TSP), (B,D) nonoptimal sheath position (anterior TSP). LAO, left anterior oblique; TSP, transseptal puncture. Adapted with permission from Hozman et al. [25].

Figure 9. (a) A 70-year-old gentleman with atrial fibrillation on an appropriate dosage of warfarin was found to have a LAA thrombus on cardiac CT. Despite increasing the target INR range to 3-4, the filling defect persisted on repeat cardiac CTs (delayed phase shown here in images (A,B)), with a Hounsfield Unit of consistently < 50 HU. (b) The patient underwent a TOE to further assess the LAA for the presence of a persistent thrombus despite optimal anticoagulation. (A) X-plane 2D TOE showing a possible spontaneous echo contrast in the distal LAA, also seen on the 3D multiplanar reformat (B). (C) Pulsed-wave velocity assessment of the LAA showed a doppler velocity of 17 cm/s, in keeping with slow flow or spontaneous echo contrast. However, on the 3D glass view analysis (D), the entire appendage is clearly visualised with no evidence of thrombus, highlighting the importance of advanced 3D TOE as the gold standard imaging modality for the assessment of LAA thrombus. The patient underwent successful LAAO with no complications, and follow-up imaging showed no evidence of PDL or DRT. TOE: Transoesophageal echocardiogram; LAA: Left atrial appendage; LAAO: Left atrial appendage occlusion; 2D:…

Figure 10. Conventional 2D transoesophageal echo view (0, 45, 90, and 135°) of the left atrial appendage and surrounding structures. AV: Aortic valve; MV: Mitral valve; PA: Pulmonary artery; PV: Pulmonary vein; Cx: Left circumflex artery.

Figure 11. (A) Transoesophageal echo (TOE) image showing the potential device landing zone in the 0°, 45°, 90°, and 135° views. It should be measured from the origin of the circumflex artery to the roof of the LAA at least 10–20 mm below the ligament of Marshall/coumadin ridge. Depth is measured from the plane of landing zone to the LAA apex. Adapted with permission from Ramchand et al. [29]. (B) Three-dimensional LAA measurement. MultiVue mode is employed on the LAA 3D Zoom image, and at the end of the systole, the landing zone positioning line (blue line) in the LAA sagittal plane (upper left) and coronal plane (upper right) are adjusted to obtain the LAA landing zone cross-section (lower left), and the LAA LZ maximum diameter (the first Dist value obtained), minimum diameter (the second Dist value), area, and circumference (Circ) are manually measured. The lower right figure shows 3D downward view of the LAA LZ and the measurement results. Adapted with permission from Sun et al. [27].

Figure 12. (a) Conversion of conventional real-time 3D transoesophageal echocardiography to TrueVue Glass. (A) From left to right, conventional 3D, TrueVue, and TrueVue Glass imaging modes of the LAA at the entrance of the left atrium are shown. The TrueVue Glass (right) shows the three lobular structures at the blind end of the LAA (arrows). (B) From left to right, conventional 3D, TrueVue, and TrueVue Glass imaging of the LAA in lateral view are shown. 3D: three-dimensional; LA: Left atrium; LAA: Left atrial appendage. Adapted with permission from Sun et al. [27]. (b) Three-dimensional (3D) multiplanar reformat images depicting the anatomical relationship of the LAA with the surrounding structures as seen with 3D TOE. AV: Aortic valve; MV: Mitral valve; PA: Pulmonary artery; LAA: Left atrial appendage; IAS: Inter-atrial septum; TOE: Transoesophageal echocardiogram.