|Procedural Step||Remarks Regarding Imaging|
|1. Transseptal puncture||The optimal transseptal puncture site, located superiorly and posteriorly in the interatrial septum, is determined by 2D TEE imaging planes:|
|2. Introduction of the SGC into the LA||The dilator is identified by a cone-shaped tip with echogenic ridges. To prevent damage of the left atrial wall, advancement of the SGC is done under continuous 2D or 3D TEE and fluoroscopic monitoring. After the SGC is positioned in the LA, the dilator and guidewire are removed.|
|3. Advancement of the clip delivery system into the LA||The location of the clip delivery system and the clip are continuously imaged to ensure that the tip does not injure the free left atrial wall. 3D TEE and x-plane imaging are useful to assess the distance of the clip delivery system from the left atrial wall.|
|4. Steering and positioning of the MitraClip above the MV||The positioning of the clip delivery system above the MV is best guided by 3D TEE imaging. On 2D TEE imaging, medial-lateral clip adjustments are monitored in a midesophageal intercommissural view and anterior-posterior adjustments in orthogonal midesophageal long-axis views. The MitraClip should be directed toward the largest PISA and split the MR jet. A short-axis transgastric view can be used to assess clip orientation when only 2D TEE imaging is available. Three-dimensional TEE en face views generally allow precise orientation of the MitraClip arms in the LA.|
|5. Advancing the MitraClip into the LV||Seen on fluoroscopy and with x-plane imaging in which the intercommissural view (60° to 90°) and the left ventricular outflow tract view (110° to 130°) are simultaneously visualized. The left ventricular outflow tract view is used to show the open clip arms. In the intercommissural view no parts of the clip arms should be seen. As the guiding catheter and clip may rotate during advancement from the LA to the LV, a 2D transgastric short-axis view or 3D imaging from either the LA or the LV is used to reassess the clip orientation in relation to the MV and the line of coaptation.|
|6. Grasping of the leaflets and assessment of proper leaflet insertion||The clip is opened below the MV and the orientation is rechecked. Closed partially, the clip is brought up to grasp the leaflets. Leaflet grasping is best performed by using x-plane imaging (bicommissural and long-axis). A true bicommissural view is essential, as the long-axis view is generated from it. To find a true bicommissural view, we often use a technique in which a half-box of 3D TEE imaging is generated and should cut through the medial and lateral commissures. The clip is fully closed after demonstrating adequate insertion of both leaflets and a reduction in MR severity. Multiple imaging planes are used to assess for adequate leaflet insertion.|
|7. Clip detachment||The insertion of an adequate amount of leaflet tissue (of both leaflets) into the clip is essential to reduce the risk for embolization and is confirmed by TEE imaging. 3D TEE imaging is helpful to determine the ultimate orientation of the grasp, and to assess for valve distortion due to off-axis grasping.|
LA = left atrium; LV = left ventricle; PISA = proximal isovelocity surface area; SGC = steerable guide catheter; TEE = transesophageal echocardiographic; other abbreviations as in Tables 1, 2, and 3.
↵∗ While determining the ideal site for obtaining access to the LA through a transseptal puncture can be performed with the use of fluoroscopy, traditional fluoroscopically-guided puncture techniques do not afford the same amount of precision and do not allow for the assessment of pericardial effusion before and after the transseptal puncture compared to TEE imaging. Also see Figure 10.