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(left), had multiple piezoelectric crystals distributed along its length that obtained images as the probe was withdrawn from the esophagus.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.

Perhaps the most spatially complex lesions addressed in the catheterization laboratory are periprosthetic valvular leaks. Dehiscence of a mitral valve annuloplasty ring or prosthesis, for instance, often results in a single elliptical defect, but multiple defects also may be present. Before starting such an intervention, a thorough evaluation of the relationship between the mitral annulus and the implant is essential to identify the site of the largest defect and the most significant periprosthetic regurgitation. In this setting, RT3DTEE provides significant additional detail that 2DTEE cannot.^7,8 During the intervention, RT3DTEE facilitates positioning of wires, catheters, and the closure device. In a patient with a mechanical valve, this modality can help ensure that device deployment does not restrict prosthetic disk motion. Finally, RT3DTEE can be used to reevaluate mitral regurgitation at the conclusion of the intervention. In summary, transcatheter repair of periprosthetic regurgitation is very difficult, if not impossible, to perform effectively without the use of RT3DTEE guidance (Figures 14-10 to 14-16; Video 14-3).

Figure 14-10 Before clip deployment, three-dimensional transesophageal echocardiography facilitates clip positioning perpendicular to the line of leaflet coaptation (right). This ensures that the clip can simultaneously grasp the anterior and posterior leaflets. MV, mitral valve.

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

Figure 14-11 On two-dimensional transesophageal echocardiography with color Doppler in the apical long-axis view, dehiscence of a mechanical mitral valve prosthesis is suggested by the echo-free space between the valve leaflets and the native annulus (A, arrow) as well as an eccentric mitral regurgitation jet external to the ring (B). With two-dimensional echocardiography, it is difficult to define the true location and extent of the prosthetic dehiscence.

Figure 14-12 In this zoom mode, three-dimensional transesophageal echocardiography image from the left atrial view, the precise location of a mechanical mitral valve dehiscence—in this case, at the posterolateral aspect of the annulus—can be appreciated (A, arrow). Color Doppler confirms the presence of mitral regurgitation at this site (B, arrow). Interestingly, most mitral valve dehiscences occur along the posterior aspect of the annulus. There are two potential explanations for this phenomenon. First, the anteriorly located aortic-mitral curtain, a fibrous structure providing continuity between the anterior mitral valve leaflet and the aortic valve in the roof of the left ventricle, serves as a secure anchor for the anterior aspect of the valve. The posterior aspect of the annulus, in contrast, contains more adipose tissue. Second, because the left circumflex coronary artery is close to the posterior aspect of the annulus, it is technically difficult to suture the corresponding portion of the valve securely without damaging the artery (see Video 14-3).

Figure 14-13 This mitral valve annuloplasty ring, seen on three-dimensional transesophageal echocardiography from the left atrial (LA) (A) and left ventricular (LV) (B) views, is dehisced along its posterolateral aspect (arrows).

Figure 14-14 Percutaneous repair of this bioprosthetic mitral valve dehiscence is guided by three-dimensional transesophageal echocardiography (3DTEE). The site of dehiscence is along the posterior aspect (A). Whereas conventional two-dimensional (2D) TEE with color Doppler demonstrates periprosthetic mitral regurgitation (B), the precise location and extent of the dehiscence is best appreciated with 3DTEE, which can guide placement of an interventional catheter within the area of dehiscence (C, arrow). After placement of an Amplatzer (St. Jude Medical, St. Paul, MN) occluder device (D, arrow), the mitral regurgitation is considerably lessened (E).

(Courtesy Dr. Garcia Fernandez.)

Figure 14-15 This bioprosthetic mitral valve, visualized from the left atrium on zoom mode three-dimensional (3D) transesophageal echocardiography (TEE), is dehisced posteriorly (double arrow). With live 3D imaging guidance, interventional catheters have been placed within the valve orifice (white arrow) and through the site of dehiscence (single black arrow). With two-dimensional TEE or fluoroscopy, this would be an extremely difficult task, even if biplane imaging were used.

(Courtesy Dr. Garcia Fernandez.)

Figure 14-16 This mechanical bileaflet valve, visualized from the left atrium at mid-diastole, was dehisced along its posterior aspect and has been repaired by percutaneous placement of an Amplatzer device (St. Jude Medical, St. Paul, MN) (arrow).

(Courtesy Dr. Garcia Fernandez.)

Immediately following any catheter-based intervention, RT3DTEE can be used to confirm procedural success. After a device is deployed, it can be examined in multiple views while the patient is still in the interventional suite. This may obviate the need for follow-up imaging studies, repeat intervention, or both. If subsequent imaging is indicated on the basis of changes in clinical status or concerns regarding device stability, subsequent 3D transthoracic echocardiography (3DTTE) may be performed, and the images may be compared with those obtained during the procedure.

In addition to interventions for structural heart disease, RT3DTEE also shows promise for guidance of catheter-based arrhythmia ablation. In pulmonary vein isolation for atrial fibrillation, RT3DTEE can identify the orifices of the veins and confirm appropriate catheter tip placement. Unlike 2DTEE or ICE, it clearly demonstrates the relationship of the catheters to the endocardial surface. With RT3DTEE, it often is possible to see the entire length of a catheter within a region of interest, facilitating precise catheter manipulation (Figures 14-17 to 14-32).⁹ The utility of RT3DTEE in electrophysiologic procedures is an area that deserves further study.

Figure 14-17 Real-time three-dimensional, zoom mode transesophageal echocardiography provides an en face view of this patent foramen ovale (PFO, arrow) from the left atrium. The flap of the septum secundum (asterisk) is partially in contact with the septum primum, but a defect remains. IAS, interatrial septum.

Figure 14-18 In the assessment of this large ostium secundum atrial septal defect, three-dimensional transesophageal echocardiography (A) closely replicates the surgeon’s view from the right atrium (B). Ao, aorta; SVC, superior vena cava; TV, tricuspid valve.

Figure 14-19 This ostium secundum atrial septal defect can be viewed from either the right (A) or left atrial (B) view with three-dimensional transesophageal echocardiography in zoom mode.

Figure 14-20 Real-time three-dimensional transesophageal echocardiography guidance assists in initial visualization of the atrial septal defect (ASD) from the right atrium (RA, A), passage of a guidewire (B) and occluder delivery catheter (C) through the defect, deployment of the left atrial disk (D), and positioning (E) and deployment (F) of the right atrial disk. With this method, good apposition of both disks with the interatrial septum (IAS) can be confirmed before the end of the procedure. IVC, inferior vena cava; LA, left atrium; SVC, superior vena cava.

Figure 14-21 In this modified four-chamber two-dimensional transesophageal echocardiography (TEE) image (left), the guide catheter (arrow) crosses the interatrial septum from the right atrium (RA) to the left atrium (LA). Intracardiac echocardiography (ICE, middle) also demonstrates this (upper arrow, interatrial septum; lower arrow, guide catheter). However, only real-time three-dimensional TEE (right, top and bottom) clearly demonstrates that the guide catheter (arrows) is truly crossing through the atrial septal defect.

Figure 14-22 Sizing balloons (SB) typically are used to evaluate atrial septal defect dimensions before selection of an appropriately sized Amplatzer occluder device (St. Jude Medical, St. Paul, MN). With two-dimensional transesophageal echocardiography (TEE) (modified bicaval view, top left) and intracardiac echocardiography (ICE, lower left), the sizing balloon is viewed obliquely, as in the real-time three-dimensional (3D) TEE long-axis (LAX) view (middle, top). Only the 3DTEE short-axis (SAX) view from the right atrium (middle, bottom) clearly depicts the true diameter of the balloon, allowing for more accurate Amplatzer sizing. It is also possible to calculate the volume of an atrial septal defect using full-volume acquisition with offline processing and specialized quantitative software (right). IAS, interatrial septum; RA, right atrium.

Figure 14-23 Appropriate positioning of the right atrial (RA) disk (A, asterisk) and left atrial (LA) disk (B, black arrow) can be confirmed by real-time three-dimensional transesophageal echocardiography prior to removal of the delivery catheter (white arrows).

Figure 14-24 Real-time three-dimensional transesophageal echocardiography in multiple views demonstrating good apposition of both disks of the Amplatzer device (St. Jude Medical, St. Paul, MN) with the interatrial septum (arrows). LA, left atrial; RA, right atrial.

Figure 14-25 Before percutaneous closure of the left atrial appendage (LAA), this zoom mode real-time three-dimensional transesophageal echocardiography image allows quantification of LAA dimensions for proper device sizing.

Figure 14-26 As in percutaneous mitral valve repair, real-time three-dimensional transesophageal echocardiography is an excellent means of guiding transseptal puncture and visualizing catheter placement for a percutaneous left atrial appendage (LAA) occlusion procedure. After deployment of an LAA occluder device (arrow), this view from the left atrium demonstrates appropriate device position. Superimposed color Doppler also may be used to confirm the absence of communication between the LAA and the left atrium.

Figure 14-27 A large left atrial appendage (LAA) thrombus is seen on this two-dimensional transesophageal echocardiography (TEE) image (A, arrow), along with spontaneous echocardiographic contrast in the left atrium suggesting stasis. With real-time three-dimensional TEE (B, arrow), it is easier to appreciate the volume of the thrombus. This is an example of a complication of percutaneous closure of the LAA.

Figure 14-28 Real-time three-dimensional transesophageal echocardiography can be used to guide the positioning of a lasso catheter (arrows) at the site of the right upper pulmonic vein prior to an atrial fibrillation ablation procedure.

Figure 14-29 A large thrombus is noted in a dilated pulmonic vein by two-dimensional (A) and three-dimensional (B) echocardiography. Note the ridge separating the pulmonic vein from the left atrial appendage (arrows).

Figure 14-30 These two-dimensional transesophageal echocardiography images show thinning of the interventricular septum (arrow) and color flow across the septum consistent with a muscular ventricular septal defect.

Figure 14-31 This real-time three-dimensional transesophageal echocardiography zoom mode image, obtained from the mid-esophageal window, shows the ventricular septal defect (VSD) in Figure 14-30 en face (oval) from the left ventricle. It is possible to measure the VSD’s dimensions precisely to facilitate selection of a repair device. Color Doppler could be used to illustrate flow across the defect.

Figure 14-32 Deployment of a ventricular septal defect closure device can be guided by real-time three-dimensional (3D) transesophageal echocardiography (TEE). A two-dimensional TEE four-chamber image (A) shows the closure device, but the right ventricular half of the device (arrow) appears somewhat hazy, making it difficult to determine whether it is appropriately deployed. With 3DTEE, the edge of the device is clearly delineated (B, arrow).

Because image acquisition is relatively rapid with current technology, RT3DTEE does not appear to lengthen procedure times. One small, retrospective study of interatrial communication closures found that RT3DTEE, when added to 2DTEE, was associated with a reduction in fluoroscopy times.¹⁰ In a catheterization laboratory where many complex interventions are performed, such a finding could translate into a meaningful reduction in radiation exposure for staff and patients.

RT3DTEE imaging requires a multiplane TEE probe, which also is capable of 2D imaging, so no probe exchange is required during a procedure. Typically, the echocardiographer uses 2D imaging to find the appropriate window, then switches to 3D full-volume mode for initial 3D imaging. Cardiac structures of interest can then be selectively examined with zoom mode imaging. Compared with ICE, TEE requires additional sedation for patient comfort and closer airway monitoring, but it does not require placement of a large-bore intravenous catheter, potentially reducing the risk of bleeding complications. Furthermore, the TEE probe is reusable, whereas an ICE catheter is single use and quite costly.

Current limitations of RT3DTEE include motion artifacts, which are worsened by respiratory motion; tissue dropout, which can result in blurred images; and visual delay with moving structures. Anterior cardiac structures, such as the tricuspid and aortic valves, may be less well visualized than more posterior structures, such as the mitral valve and left atrial appendage.⁴ Larger, controlled trials are needed to determine definitively whether RT3DTEE can improve procedural outcomes.