Guidance of Catheter-Based Cardiac Interventions

Over the past 2 decades, percutaneous interventions for structural heart disease have become increasingly common. Interventional cardiologists are now treating a variety of lesions that previously required surgery, and these interventions have become more technically complex over time. Although fluoroscopy, two-dimensional transesophageal echocardiography (2DTEE), and intracardiac echocardiography (ICE) are most typically used for procedural guidance, real-time three-dimensional TEE (RT3DTEE) offers several important advantages over these modalities (Figure 14-1).¹

Figure 14-1 The first three-dimensional transesophageal echocardiography (3DTEE) probe, termed the “lobster” (left), had multiple piezoelectric crystals distributed along its length that obtained images as the probe was withdrawn from the esophagus. The subsequent OmniPlane III probe (Philips Healthcare, Andover, MA) (middle, left) required a rotational technique for sequential data acquisition, followed by offline processing. The xMATRIX TEE (MTEE) probe (Philips Healthcare) (middle, right) allows rapid, automated acquisition and display of 3D images in real time. In full-volume mode, the matrix TEE probe can be used to visualize the left ventricle, as shown (right). The zoom mode allows more detailed imaging of structures such as valves and the left atrial appendage.

First and foremost, RT3DTEE represents the anatomy and pathology of interest in an intuitive manner. Although the echocardiographer’s expertise is required for image acquisition, those with relatively little training in cardiac imaging can understand 3DTEE images with little difficulty. For example, simultaneous visualization of all six mitral valve scallops is possible in one view in the vast majority of patients, making RT3DTEE ideal for transcutaneous mitral valve repair using the Mitra Clip device (Abbott Vascular, Abbott Park, IL).^2–4 In this procedure, the “clip” is delivered to the left atrium via transseptal puncture. RT3DTEE can facilitate this portion of the procedure by demonstrating tenting of the interatrial septum, allowing optimal positioning of the Brockenbrough needle for the septal puncture. For this particular procedure, it is optimal to be slightly superior and posterior to the center of the fossa ovalis. Once the mitral valve clip has been passed into the left atrium, it must then be positioned perpendicular to the line of leaflet coaptation, in the center of the valvular orifice. The clip is deployed to grasp the A2 and P2 scallops. Because spatial relationships on RT3DTEE closely mirror the actual anatomy, an interventionalist can use RT3DTEE to guide catheter movements, verify device placement, and confirm that the mitral valve orifice has been appropriately cleaved in two (Figures 14-2 to 14-8; Videos 14-1 and 14-2).

Figure 14-2 Real-time three-dimensional transesophageal echocardiography can be used to guide interatrial septal puncture, a technique commonly required for percutaneous electrophysiologic and valvular procedures. Tenting of the interatrial septum by the needle (arrow) confirms that the needle is passing appropriately from the right atrium to the left atrium (see Video 14-1).

Figure 14-3 Shown is a continuation of the procedure in Figure 14-2. The catheter can then safely traverse the interatrial septum (arrow) to gain access to the left atrium, the mitral valve, or both. In Video 14-2, it is clear that two catheters are present.

Figure 14-4 In lengthy catheter-based procedures, thrombus formation on the tip of the catheter can have significant adverse consequences, such as myocardial infarction and stroke. Thrombi attached to catheters, such as the one seen here (arrow), often are easier to appreciate with three-dimensional transesophageal echocardiography compared with two-dimensional echocardiography.

Figure 14-5 Visualization of the mitral valve leaflets is more intuitive with three-dimensional echocardiography than with two-dimensional echocardiography. In the left atrial, or “surgeon’s” view, the anterior leaflet (A) and posterior leaflet (P) are clearly seen as distinct structures. In this example of rheumatic mitral stenosis, commissural fusion and reduced leaflet excursion can be appreciated. For accurate quantitation of the mitral orifice area, real-time three-dimensional transesophageal echocardiography is the method of choice.

Figure 14-6 The use of multiplanar reconstruction allows accurate measurement of the mitral orifice area. With real-time three-dimensional echocardiography, it is possible to perform planimetry truly at the tips of the mitral valve leaflets in the zoom mode, en face view (bottom right).

Figure 14-7 A, In percutaneous balloon mitral valvuloplasty, an hourglass-shaped Inoue balloon (arrow) is used. This series of images from the left atrial view shows the balloon before it crosses the valve (A and B), as it crosses the valve from left atrium to right ventricle (C and D), during inflation (E), and immediately following inflation (F).

(Courtesy Dr. Vahanian and Dr. Brochet, Bichat Hospital, Paris.)

Figure 14-8 After percutaneous balloon mitral valvuloplasty (PBMV), the mitral valve orifice is clearly larger. The arrows indicate the splitting of the commissures.

(Courtesy Dr. Vahanian and Dr. Brochet, Bichat Hospital, Paris.)

RT3DTEE is invaluable in preprocedural planning, particularly when device sizing is a concern. For instance, when a device must be selected for atrial septal defect (ASD), ventricular septal defect (VSD), or patent foramen ovale closure, 3DTEE can provide a true en face view of the defect so that its dimensions can be accurately measured. Such a defect often is elliptical or fenestrated such that 2D imaging cannot fully capture its complex shape.⁵ Furthermore, the relationship of a defect to vital structures such as the aortic root (in ASD closure) or mitral valve (in VSD closure) is easier to appreciate on RT3DTEE. This may help the interventionalist avoid complications during device deployment (Figure 14-9).

Figure 14-9 Percutaneous mitral valve repair, performed for severe mitral regurgitation, requires catheter-based delivery of a clip that grasps both valve leaflets. In this left atrial view, the clip delivery catheter (arrow) passes through the mitral valve orifice. Performance of this percutaneous procedure has been greatly facilitated by the use of real-time three-dimensional transesophageal echocardiography.

(Courtesy Dr. Kronzon, Lennox Hill Hospital, New York.)

Because RT3DTEE can accurately characterize orifice areas and shapes, it also is well suited for catheter-based left atrial appendage (LAA) closure. RT3DTEE allows optimal visualization of the LAA in the vast majority of patients. 2DTEE tends to underestimate orifice area values, but RT3DTEE findings were shown to correlate well with computed tomography in one small study.⁶ Accurate device sizing and positioning are critical in this procedure to avoid complications such as device embolization, stroke, and hemopericardium from appendage laceration. RT3DTEE is used to guide transseptal puncture, catheter manipulation in the left atrium, and device deployment. Prior to the conclusion of the procedure, RT3DTEE confirms stability of the device.