Role of Imaging in Interventions on Structural Heart Disease
Atrial fibrillation (AF) is associated with a four- to fivefold increased risk of thromboembolic stroke. It accounts for up to 15% of strokes regardless the age. This percentage reaches 30% in people >75 years.
For more than 50 years, vitamin K antagonists have been the primary medication to reduce the risk of thromboembolic events in patients with AF. Nevertheless, along with proven clinical efficacy, they have several limitations, including a number of interactions with other drugs and food, and need for regular blood monitoring for dose adjustments.
It has been recognized that the LAA is the main anatomical site for thrombus formation, therefore the concept of eliminating such risk without the use of anticoagulants has been recently substantiated into some specific devices designed to percutaneously occlude the LAA: the PLAATO (Percutaneous LAA Transcatheter Occlusion) device (Appriva Medical Inc., Sunnyvale, CA, USA), the WATCHMAN system (Atritech Inc., Plymouth, MN, USA) and the Amplatzer Septal Occluder device (AGA Medical Corp., Plymouth, MN, USA).
Two diagnostic tools are crucial to define anatomy of LLA before the procedure in order to assess the anatomy of LLA that may be multilobated and very variable in size: TEE and MSCT (Figure 24).
(Enlarge Image)
Figure 24.
Pre-interventional 2DTEE, 3DTEE and multi-slice computed tomography scan for left atrial appendage.
TEE is gold standard to evaluate the LAA which is rarely and always incompletely visualized by the transthoracic echocardiogram.
TEE is also pivotal, along with fluoroscopy, to guide the intervention performed during general anesthesia.
Specific information that TEE could provide includes: presence of thrombus, that is a contraindication to the procedure, guidance to transseptal puncture, morphology of the LAA (presence and extent of lobes) in short and long axis views to obtain the maximal measurement of the orifice and neck of the LAA, measures of the ostium of the LAA, which is usually elliptic rather than circular, to assess the proper device size, the size of the 'landing zone' where the device will be positioned, the depth of the LAA, the correct alignment of the external disk of the device with the long axis of the LAA, final position and stability of the device including a precise assessment of any residual flow into the LAA, spatial relation with the mitral valve. Figure 25 shows pre-intervention LAA measurements, and LAA occlusion after the deployment of the device.
(Enlarge Image)
Figure 25.
TEE sizing of left atrial appendage and after device released in X-plane and 3D.
Left Atrial Appendage Closure
Atrial fibrillation (AF) is associated with a four- to fivefold increased risk of thromboembolic stroke. It accounts for up to 15% of strokes regardless the age. This percentage reaches 30% in people >75 years.
For more than 50 years, vitamin K antagonists have been the primary medication to reduce the risk of thromboembolic events in patients with AF. Nevertheless, along with proven clinical efficacy, they have several limitations, including a number of interactions with other drugs and food, and need for regular blood monitoring for dose adjustments.
It has been recognized that the LAA is the main anatomical site for thrombus formation, therefore the concept of eliminating such risk without the use of anticoagulants has been recently substantiated into some specific devices designed to percutaneously occlude the LAA: the PLAATO (Percutaneous LAA Transcatheter Occlusion) device (Appriva Medical Inc., Sunnyvale, CA, USA), the WATCHMAN system (Atritech Inc., Plymouth, MN, USA) and the Amplatzer Septal Occluder device (AGA Medical Corp., Plymouth, MN, USA).
Two diagnostic tools are crucial to define anatomy of LLA before the procedure in order to assess the anatomy of LLA that may be multilobated and very variable in size: TEE and MSCT (Figure 24).
(Enlarge Image)
Figure 24.
Pre-interventional 2DTEE, 3DTEE and multi-slice computed tomography scan for left atrial appendage.
TEE is gold standard to evaluate the LAA which is rarely and always incompletely visualized by the transthoracic echocardiogram.
TEE is also pivotal, along with fluoroscopy, to guide the intervention performed during general anesthesia.
Specific information that TEE could provide includes: presence of thrombus, that is a contraindication to the procedure, guidance to transseptal puncture, morphology of the LAA (presence and extent of lobes) in short and long axis views to obtain the maximal measurement of the orifice and neck of the LAA, measures of the ostium of the LAA, which is usually elliptic rather than circular, to assess the proper device size, the size of the 'landing zone' where the device will be positioned, the depth of the LAA, the correct alignment of the external disk of the device with the long axis of the LAA, final position and stability of the device including a precise assessment of any residual flow into the LAA, spatial relation with the mitral valve. Figure 25 shows pre-intervention LAA measurements, and LAA occlusion after the deployment of the device.
(Enlarge Image)
Figure 25.
TEE sizing of left atrial appendage and after device released in X-plane and 3D.
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