Transesophageal echocardiography (TEE) and intracardiac echocardiography (ICE) have revolutionized the ability to monitor and direct intraoperative surgical procedures and interventional cardiac catheterization procedures for patients with congenital heart disease. TEE has been the traditional imaging modality of choice for the past two decades in the operating suite and catheterization laboratory. More recently, the miniaturization of echocardiography technology has permitted ICE probes to be used in children and adults. Each imaging modality has advantages, disadvantages, and limitations, but the availability of both modalities has improved patient care in the operating suite and cardiac catheterization laboratory. Important limitations of TEE include the need for general anesthesia and potential problems related to airway management during prolonged use in the supine patient. Imaging limitations of TEE include some views of the posterior and inferior atrial septum that may be inadequate to exclude significant defects or shunts. The close proximity of the TEE probe to that area of the atrial septum creates this imaging issue. During atrial septal defect (ASD) device placement, with TEE there may be struggles with artifact when attempting to image through the device. In addition, the apical ventricular septum may be relatively inaccessible with TEE in some patients. For these reasons, the availability of high-quality intracardiac imaging has successfully merged the cardiac catheterization and echocardiography practices for patients with congenital heart disease.
Mechanical ICE systems were introduced in the 1980s. The current ICE system using an 8 or a 10 French (Fr) phased-array system was developed from single-array TEE prototype probes. The initial ICE probe was a 10 Fr catheter (AcuNav Diagnostic Ultrasound Catheter; Siemens Corporation, Mountain View, CA). This probe is a 64-element vector, phased-array transducer that is multifrequency (5.5 to 10 MHz) and mounted on a 3.3-mm (10 Fr) catheter with a maneuverable four-way tip (Fig. 35.1). The probe is capable of high-resolution two-dimensional and full Doppler imaging (pulsed-wave, continuous-wave, and tissue Doppler). The longitudinal plane provides a 90-degree sector image with tissue penetration of 2 to 12 cm. Currently, this probe is also available as an 8 Fr catheter. This catheter has similar echo capabilities but is longer than the 10 Fr catheter. The added length of the 8 Fr probe makes it more difficult to manipulate. The ICE catheter is advanced to the right atrium under fluoroscopic guidance. Image quality is optimized by adjusting gain, depth, frequency, and focal length controls. Complete ICE evaluation of both sides of the heart is then performed, sometimes with assistance of fluoroscopy to guide orientation and position of the ICE catheter.
Figure 35.1. Intracardiac echo probe. A: Diagnostic ultrasound catheter (AcuNav) placed adjacent to a pediatric transesophageal echocardiography probe shows the relatively small size of the 10 Fr catheter. B: Close-up of the 3.3-mm-diameter catheter tip (arrows) shows the longitudinally oriented crystal array (palette). C: Overhead view of the four-way tip maneuverability of the diagnostic catheter.
The movements described in this chapter relate to the manipulation of the control mechanisms on the handle of the ICE catheter. Movement of the control handle to the left of midline results in movement of the catheter tip to the left as visualized from the front of the probe handle. However, these movements may not result in movement of the catheter tip in the same direction as illustrated outside of the body because, during an examination, the imaging palette is also being rotated in various directions to achieve a particular image plane. The imaging palette of the probe can be identified by the black stripe on the outside of the catheter and the black side of the probe evident on fluoroscopy. Thus, if the probe has been rotated to visualize a posterior structure (palette-directed posterior), posterior or rightward movement of the probe handle controls results in a more medial position of the catheter tip toward the atrial septum. When the catheter is angulated into unusual positions, such as the position required to achieve a short-axis image plane (anterior and leftward control movement), simple rotation of the catheter does not result in the longitudinal scanning effect as in TEE, but, rather, the tip of the probe moves in a large 360-degree arch. In practice, either the echo images can be followed and the probe manipulated to obtain the desired images, or the position of the probe tip can be monitored by fluoroscopy to obtain a standard probe position.
By advancing the ICE catheter from the inferior vena cava with the control mechanism in a free or neutral position, the catheter is placed in the mid right atrium, and a tricuspid valve inlet view is obtained by rotating the imaging palette of the catheter anteriorly and slightly leftward (Fig. 35.2). The catheter tip is then rotated clockwise to visualize the aorta and left ventricular outflow tract (Fig. 35.3). The lower atrial septum (cardiac crux) and mitral valve are then visualized by further clockwise catheter rotation (Fig. 35.4). In some cases, with some posterior control movement there is posterior deflection of the catheter tip, and a classic four-chamber view of the cardiac crux may be obtained as shown in Figure 35.4D. With continued clockwise rotation and cranial advancement of the catheter, a long-axis view of the atrial septum is obtained (Fig. 35.5).
In most cases, some leftward or anterior control movement with resultant lateral deflection of the catheter tip is needed to optimize this long-axis image by moving the transducer tip back and away from the atrial septum. With further cranial and caudal positioning of the catheter and slight counterclockwise and clockwise rotation, the entire atrial septum is evaluated with two-dimensional and color flow imaging. Usually, the lipomatous superior margin of the atrial septum (septum secundum) is clearly recognized, as is the membrane of the fossa ovalis (Fig. 35.6). From this same position, posterior, leftward imaging beyond the atrial septum allows visualization and evaluation of the left atrium and the left upper and lower pulmonary veins as they course in front of the descending thoracic aorta (see Fig. 35.5). The pulmonary veins are evaluated further by color flow imaging and pulsed-wave Doppler interrogation. Continued clockwise rotation then allows subsequent evaluation of the right lower pulmonary vein and subsequently the right upper pulmonary vein (Fig. 35.7), which is anterior and inferior to the right pulmonary artery. In some patients, visualization of the right pulmonary veins requires not only clockwise rotation but also some cranial advancement of the probe. With anterior flexion of the catheter tip by anterior and leftward control movement, the superior vena cava (SVC) is then evaluated (Fig. 35.8). The crista terminalis is often visible near the SVC.
Figure 35.2. Tricuspid valve inflow view with ICE. A: Illustration of catheter course and probe position for right ventricular inflow view. B: Anteroposterior radiograph reveals the intracardiac echocardiography catheter tip in the right atrium (arrow) with the transducer palette pointed toward the tricuspid valve. C: Lateral radiograph shows the corresponding lateral image with the transducer tip (arrow) pointed anteriorly. D: Corresponding intracardiac echocardiography image of the tricuspid valve and right ventricle (RV) with mild tricuspid insufficiency shown with color flow imaging. L, left; PA, pulmonary artery; RA, right atrium; S, superior.
Figure 35.3. Evaluation of aorta and left ventricular outflow tract with ICE. A: Illustration of catheter course and probe position for view of the left ventricular outflow tract and aortic valve. B: Anteroposterior radiograph shows the intracardiac echocardiography catheter (arrow) now rotated slightly clockwise to point to the left ventricular (LV) outflow tract. C: Lateral image of the same catheter position (arrow). D: Corresponding intracardiac echocardiography image of the left ventricular outflow tract with color flow imaging. Ao, ascending aorta; L, left; MPA, main pulmonary artery; RA, right atrium; S, superior.
FIGURE 35.4. Evaluation of atrial septum and cardiac crux with ICE. A: Illustration of catheter course and probe position for view of the lower atrial septum and crux of the heart. B: Anteroposterior radiograph shows the intracardiac echocardiography catheter (arrow) further rotated clockwise to image the cardiac crux portion of the atrial septum above the mitral valve. C: Lateral image of this catheter position (arrow). D: Corresponding intracardiac echocardiography image of the cardiac crux (arrow) just above the mitral valve and coronary sinus (CS). E: Four-chamber view of the cardiac crux shows small right-to-left shunt across patent foramen ovale (arrow). I, inferior; L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.
Figure 35.5. Long-axis view of atrial septum with ICE. A: Illustration of the catheter course and probe position for the long-axis view of the atrial septum. B: Anteroposterior radiograph of the intracardiac echocardiography catheter (arrow) after further clockwise rotation and slight anterior and lateral retroflexion of the catheter reveals a long-axis intracardiac echocardiography image of the atrial septum. C: Lateral image of the catheter position (arrow) shows the slight anterior flexion of the catheter. D: Corresponding intracardiac echocardiography image of the long axis of the atrial septum (arrow) thus obtained. E: Color flow image of left pulmonary venous return and a small left-to-right atrial shunt (arrow). A, anterior; DAo, descending aorta; LA, left atrium; LLPV, left lower pulmonary vein; LPA, left pulmonary artery; LUPV, left upper pulmonary vein; P, posterior; RA, right atrium; S, superior.
Figure 35.6. Evaluation of patent foramen ovale with ICE. A: Intracardiac echocardiography long-axis image reveals a large patent foramen ovale (PFO) (10 mm) in a 25-year-old patient with a previous stroke. B: Corresponding color flow image shows a large right-to-left shunt through the PFO (arrow).C: The same long-axis image of the PFO with a large resting right-to-left shunt (arrow) shown with an inferior vena caval agitated saline injection. A, anterior; DAo, descending aorta; LA, left atrium; P, posterior; RA, right atrium; S, superior.
FIGURE 35.7. Evaluation of right pulmonary veins with ICE. A: Illustration of the catheter course and probe position for viewing the right pulmonary veins. B: Anteroposterior radiograph reveals intracardiac echocardiography catheter tip position (arrow) after further clockwise catheter rotation to the right to image the right pulmonary veins. C: Lateral radiograph shows catheter position (arrow). D: Corresponding intracardiac echocardiography image shows all three right pulmonary veins. Note that the right upper pulmonary vein (RUPV) courses anterior and then inferior to the right pulmonary artery (RPA). E: With the catheter tip moved across the atrial defect, the image then reveals a long-axis view of the RPA with the RUPV just inferior to the RPA. LA, left atrium; P, posterior; R, right; RLPV, right lower pulmonary vein; RMPV, right middle pulmonary vein; S, superior; SVC, superior vena cava.
FIGURE 35.8. Evaluation of superior vena cava with ICE. A: Illustration of the catheter course and probe position to view the superior vena cava. B: Anteroposterior radiograph reveals anterior and lateral flexion of the catheter (arrow) to scan superiorly into the superior vena cava (SVC). C: Lateral image of the same catheter position (arrow) scanning superiorly. D: Corresponding intracardiac echocardiography image shows flow from the SVC into the right atrium (RA). The right upper pulmonary vein (RUPV) is noted as it courses anterior (A) and inferior to the right pulmonary artery (RPA). S, superior.
A short-axis image of the atrial septum and aortic root can be obtained with combined anterior and leftward control movement and with some clockwise rotation of the handle. This directs the tip anteriorly and medially toward and sometimes across the tricuspid valve annulus (Fig. 35.9). Short-axis images are important to access appropriate device positioning near the aortic root and provide a typical transverse image of the aortic valve and the atrial septum. The right lower pulmonary veins are visible near the back wall of the left atrium.
To cross the atrial septum, the catheter tip is repositioned in the mid right atrium and, with the imaging palette facing posterior to the atrial septum, is manipulated with posterior or rightward control movement to move the catheter tip toward the atrial septum. With the catheter tip seated adjacent to the atrial septum or, in many cases, across the interatrial defect, the pulmonary veins are again evaluated. Once across the septal defect, with further posterior and rightward control movement (catheter flexion), an en face mitral inflow view is obtained (Fig. 35.10). With the catheter across the atrial septum, in a neutral position and rotated anteriorly (counterclockwise), a detailed short-axis view of the aortic valve is obtained, and with slight clockwise rotation of the catheter, the right ventricular outflow tract and pulmonary valve are observed (Fig. 35.11). With posterior and rightward movement of the controls similar to the mitral valve view, the probe can be advanced into the left ventricle or near the lateral atrioventricular groove where scans of the ventricular septum, both atrioventricular (AV) valves, and the ventricles can be obtained similar in appearance to a four-chamber view (Fig. 35.12). This view provides excellent imaging of the inlet and membranous ventricular septum.
Returning to the right atrium, with combined anterior and leftward control movement similar to that to obtain a short-axis image, the curved probe can be manipulated across the tricuspid valve to visualize structures within the right ventricle. With advancement of the probe into the right ventricle, scans of the right ventricular outflow tract and pulmonary valve are easily obtained (Fig. 35.13). By releasing the curvature on the probe, it can then be rotated to scan inferiorly to obtain short-axis images of the left ventricle and the ventricular septum. These same views can be used to scan the membranous and muscular portions of the ventricle to visualize ventricular septal defects (VSDs) (Fig. 35.14).
Imaging Note: ALL ICE PROBE MANIPULATIONS WITHIN THE LEFT ATRIUM, LEFT VENTRICLE, AND RIGHT VENTRICLE SHOULD BE GRADUAL, GENTLE, AND PERFORMED WITH FLUOROSCOPIC GUIDANCE BECAUSE THE STIFF ICE PROBE MAY CAUSE DAMAGE TO THE VALVULAR APPARATUS AND OTHER STRUCTURES.
Three-dimensional ICE imaging is now commercially available with the Siemens SC2000 platform. The 3D ICE probe currently is only 11 French in size but also has the same functionality as the 2D catheter. The 4D images provide a real-time 20-degree 3D image. With similar catheter positioning as described with the 2D images, 3D images of the atrial septum, AV valves, and semilunar valves can be obtained (Fig. 35.15). A large recurrent ASD is better demonstrated with 3D ICE imaging as noted in Figure 35.16.
Figure 35.9. Short-axis view of atrial septum and aorta with ICE. A: Illustration of the catheter course and probe position for the short-axis view of the atrial septum and aorta. B: Anteroposterior radiograph shows retroflexion of the catheter tip by anterior and leftward movement of the probe controls and subsequent rotation of the catheter tip clockwise to place the tip (arrow) near or through the tricuspid valve. C: Lateral image reveals the catheter position (arrow) near the tricuspid valve. D: Corresponding intracardiac echocardiography image reveals a typical short-axis image of the heart at the level of the aortic valve. A small left-to-right shunt (arrow) is observed through the superior margin of the atrial septal defect. The main pulmonary artery (MPA) is also noted posterior to the aorta. A, anterior; Ao, ascending aorta; L, left; LA, left atrium; RA, right atrium.
Figure 35.10. Evaluation of the mitral valve with ICE. A: Illustration of the catheter course and probe position for an en face view of the mitral valve from the left atrium. B: Anteroposterior radiograph shows the intracardiac echocardiography catheter (arrow) advanced across the atrial septal defect and flexed inferiorly to view the mitral valve orifice. C: Lateral radiograph reveals the same catheter position (arrow). Note the posterior location of the catheter in the left atrium. D: Corresponding intracardiac echocardiography image of the en face view of the mitral orifice. I, inferior; L, left; LA, left atrium; LV, left ventricle.
Figure 35.11. Evaluation of aorta, RVOT, and pulmonary artery with ICE. A: Illustration of the catheter course and probe position for a view of the aorta and pulmonary artery from the left atrium. B: Anteroposterior radiograph of the intracardiac echocardiography catheter tip (arrow) placed across the atrial septal defect into the left atrium but rotated counterclockwise to an anterior position immediately behind the aortic valve. C: Lateral image of the same catheter position (arrow). Note that the transducer is pointing anteriorly. D: Corresponding intracardiac echocardiography image shows in the short axis the fine detail of the aortic valve leaflets. E: With additional clockwise catheter rotation, a view of the right ventricular outflow tract and main pulmonary artery (MPA) is obtained. Arrow points to aortic valve and arrowhead points to pulmonary valve. A, anterior; Ao, ascending aorta; L, left; TV, tricuspid valve.
Figure 35.12. Evaluation of ventricular septum, atrioventricular valves, and ventricles with ICE. A: Illustration of the catheter course across the atrial septum and the probe position just inside the left ventricle near the left atrioventricular groove. Rightward and posterior control movement results in angulation of the probe to view the ventricular septum and both ventricles. S, superior; L, left; LV, left ventricle; RA, right atrium; VS, ventricular septum; RV, right ventricle. B: Anteroposterior radiograph of the intracardiac echocardiography catheter tip (arrow) at the left atrioventricular groove. C: Lateral radiograph demonstrating this catheter position. D: Corresponding intracardiac echocardiography image showing a four-chamber–like view of both ventricles and the ventricular septum. The membranous to inlet portion of the ventricular septum is well visualized. E: Color flow image showing mitral inflow. F: Similar view in another patient demonstrating a systolic image. LA, left atrium.
The potential applications of ICE to interventional cardiac catheterization continue to expand, not only with respect to catheter-based treatment of congenital and acquired heart disease but also to the management of cardiac arrhythmias. ICE imaging results in improved patient comfort compared with TEE. ICE imaging bypasses potentially poor acoustic windows that are commonly encountered during transthoracic echocardiography. In addition, the use of ICE imaging allows a “single operator” concept, thereby alleviating the need for an additional echocardiographer in the catheterization laboratory, provided the primary operator is familiar with ICE imaging and interpretation. The interventionalist has control of the echocardiographic ICE images and must be able to provide the appropriate image planes for diagnosis and catheter intervention. The ability to provide this imaging rapidly and without the need for other echocardiographic support expedites the procedure and shortens interventional procedure time.
Figure 35.13. Evaluation of RVOT and pulmonary valve with ICE. A: Illustration of the catheter course and probe position across the tricuspid valve in the right ventricle. Because of the leftward and anterior control manipulation the probe is angulated to visualize the pulmonary outflow tract and valve superiorly. B: Anteroposterior radiograph of the intracardiac echocardiography catheter in the right ventricle. C: Lateral radiograph demonstrating the anterior catheter location. D: Corresponding intracardiac echocardiography image of the pulmonary outflow and color flow through the pulmonary valve. A, anterior; L, left; PA, pulmonary artery; Ao, ascending aorta.
Superior image quality and visualization of intracardiac structures allow accurate guidance of interventional procedures, thereby reducing both fluoroscopic and procedure times. Procedures where ICE imaging has been reported to be of benefit include, but are not limited to, guidance of transseptal puncture to gain access to the left atrium (Fig. 35.17), transcatheter closure device placement, radiofrequency ablation, cardiac biopsy, mitral valvuloplasty, and left atrial appendage occlusion.
The first reports of intracardiac ultrasound during electrophysiology procedures (EPS) were for use of a mechanical, single-element intracardiac echo probe. Anatomic definition was thought to be of great benefit for ablation procedures, as fluoroscopic guidance did not provide adequate tissue definition. Intracardiac imaging with the newer phased-array ICE catheter has been incorporated to guide electrophysiology procedures. Proper location of the transseptal puncture as guided by ICE has been useful in conjunction with EPS. Anatomic landmarks that are important for a successful ablation are best visualized by ICE and are not easily seen fluoroscopically. One of the most common uses of ICE imaging during EPS has been during pulmonary vein isolation for atrial flutter ablation. ICE imaging provides exact determination of the pulmonary vein anatomy (number and position), including the presence or absence of an antrum that may receive the left upper and lower pulmonary veins before joining the left atrium. Visualization of pulmonary vein ostia by ICE facilitates catheter positioning to ensure adequate tip-tissue contact for delivery of radiofrequency energy, thereby improving the success of the ablation procedure and reducing fluoroscopic times. Additionally, anatomic definition reduces the risk of inadvertent ablation deeper within the vein itself, which should reduce the occurrence of subsequent pulmonary vein stenosis. ICE imaging during ablation of ventricular arrhythmias is of particular use for the evaluation of known anatomic landmarks for certain tachycardia circuits and to evaluate catheter proximity to valves and coronary arteries.
Figure 35.14. Short-axis imaging of the LV and ventricular septum with ICE. A: Illustration of the catheter course and probe position across the tricuspid valve and with the probe directed posterior to the ventricular septum to visualize the left ventricle in short axis. B:Anteroposterior radiograph demonstrating this catheter position in the right ventricle. C: Lateral radiograph demonstrating the same catheter position. D: Corresponding echocardiographic images demonstrating the right ventricle (RV) anteriorly and the left ventricle (LV) in short axis. E: Color flow imaging demonstrating flow in the LV, and the arrow points to a small jet near the ventricular septum (VS) which represents flow from a muscular ventricular septal defect (VSD). F: More apical view demonstrating the origin (arrow) of the VSD in the LV. A, anterior; L, left.
Figure 35.15. Three-dimensional 20 degree ICE images. A: Two-dimensional long-axis ICE image of the patent foramen ovale in undergoing device closure. Arrow points to the PFO and limbus of the fossa ovalis. RA, right atrium; LA, left atrium; A, anterior; S, superior. B:3D image in the same patient and with the same probe. A clear illustration of the curvature of the limbus of the fossa ovalis (arrow), the left atrium (LA), left lower pulmonary vein (PV) and descending aorta (DAo) are also evident. C: 3D color flow images also illustrate the small left-to-right shunt present through the PFO. D: Pulsed Doppler capability is also similar to standard ICE probes. E: Rotation of the 3D image allows visualization of the undersurface of the PFO and the septum primum (arrow). RA, right atrium; LA, left atrium.
Device Closure Procedures
Another application of ICE imaging, rapidly adopted into clinical practice, has been for guidance during device closure of interatrial defects, such as secundum ASD or patent foramen ovale (PFO). ICE images provide superior imaging of the atrial septum. Assessment of the defect(s) and relationship to the surrounding cardiac structures is critical to a successful procedure and is facilitated by the proximity of the ICE catheter to the atrial walls, appendage, Eustachian valve, limbus of the fossa ovalis, and pulmonary veins. Documentation of normal pulmonary venous return to the left atrium (see Figs. 35.5 and 35.7) is an important aspect of ASD closure and is easily accomplished by ICE. Long- and short-axis views (Fig. 35.18) aid in dimensional analysis of the ASD and allow very accurate measurements of both static diameter and balloon-stretched diameter (used to select the appropriate device size) compared with fluoroscopy (Fig. 35.19).The spatial orientation of devices in relationship to surrounding cardiac structures are better visualized by ICE compared with TEE. During deployment and subsequent delivery of an occlusion device there is no shadowing of the right atrial disc of the device by the left atrial disc when ICE guidance is utilized. Therefore, ICE imaging provides superior visualization of septal rims in relationship to device position before final deployment is accomplished, reducing the risk of device embolization. In contrast, when TEE is used for evaluation of device placement, significant acoustic shadowing from the left atrial disc may preclude adequate imaging of each disc and its relationship to the atrial septum, increasing the time needed for imaging before delivery of the device in an optimal position.
Figure 35.16. Three-dimensional ICE images of ASD. A: Comparative 2D and 3D images in a patient with a large secundum atrial septal defect (arrow). The 3D images provide improved depth perception of the defect and surrounding structures. B, C: 3D ICE images of the right and left atrial aspects of the large defect demonstrating the rotational capability of the images. D: 3D ICE image after effective device closure of the ASD (ASO). RA, right atrium; MV, mitral valve; LV, left ventricle; Ao, aorta.
Figure 35.17. ICE imaging of transseptal puncture. ICE imaging utilized during cardiac catheterization to guide transseptal puncture. The transseptal needle (arrow) is observed indenting the atrial septum just below the limbus (L) of the fossa ovalis. RA, right atrium; LA, left atrium; A, anterior; S, superior.
Figure 35.18. Evaluation of ASD device closure with ICE during interventional cardiac catheterization. A: Intracardiac echocardiography image demonstrating the long axis of the atrial septum with a moderate left-to-right shunt (arrow) through a secundum atrial septal defect. B: Similar image showing an occluder device in place (arrows) with a small residual central shunt. C: A short-axis image showing a device in place behind the aortic root (Ao). RA, right atrium; LA, left atrium; A, anterior; L, left; S, superior.
Transcatheter closure of muscular VSD (congenital or post–myocardial infarction) is now possible. In a patient with post–myocardial infarction VSD, TEE imaging may not be tolerated by the more clinically compromised patient. ICE is an additional imaging modality that can be used to aid visualization of cardiac structures during defect sizing, delivery, and deployment of a septal closure device. Monitoring of tricuspid valve regurgitation is facilitated by ICE during such procedures. To visualize the VSD properly, manipulation of the ICE catheter through the tricuspid valve orifice into the right ventricle may be needed (as described earlier) (Fig. 35.20).
Periprosthetic Valvular Regurgitation
In patients with both acquired heart disease (e.g., rheumatic valvular disease) and congenital heart disease who have undergone mechanical valve replacement, perivalvular leak is a reported phenomenon. Often, acoustic shadowing by the mechanical valve precludes adequate echo imaging from one side of the valve. Depending on the intracardiac anatomy, both ICE and TEE may be needed to facilitate evaluation of such defects for location, proximity to the mechanical valve, and size of the defect. In addition, during deployment of closure devices, assurance of valve function during and after device placement is critical. Evaluation of leaflet mobility is important, and the device must not interfere with normal valve function. Continuous monitoring during device deployment, positioning, and delivery is easily accomplished with ICE (Fig. 35.21). Judicious use of TEE may be needed to fully evaluate some patients during closure of perivalvular leak but can then be minimized to facilitate patient comfort during supine imaging with the additional use of ICE.
Device closure of the left atrial appendage has been under investigation as a treatment to reduce embolic risk with chronic atrial fibrillation. ICE imaging of the appendage before device closure facilitates evaluation of thrombus in the appendage. Continuous monitoring during the interventional procedure is typically performed from the right atrium, with proximity to the left atrial structures allowing adequate visualization of the device during deployment and final delivery. Intracardiac thrombus related to the procedure can be evaluated by ICE. During mitral valvuloplasty, the use of ICE may aid in monitoring the location of the initial transseptal puncture, particularly in situations where the atrial septum is excessively thickened. Additionally, ICE may be used for assessment of valve morphology, annulus measurement, and monitoring of the results of the balloon valvuloplasty and transvenous pulmonary valve (Melody) implantation (Videos 35.1 and 35.2). As previously described for these images, it is necessary to advance the ICE probe into the right ventricle and direct the imaging plate toward the right ventricular outflow tract.
Figure 35.19. ICE imaging during interventional device closure of ASD. A: Intracardiac echocardiography image during balloon sizing of two atrial septal defects (ASDs). A balloon (asterisk) is inflated across the more inferior defect. Color Doppler imaging demonstrates a large left-to-right shunt across the more superior defect at this time. B: Two balloons (asterisks) now occlude the defects. C: Measurement of the respective balloon waists to size the ASDs. Inferior defect, 10 mm; superior defect, 18 mm. D: Device deployment. The left atrium (LA) side of the device (arrow) has been deployed across the more inferior defect. E: Anteroposterior fluoroscopic image while both balloons are inflated across the atrial septum. Note the plane of the atrial septum as identified by the balloon waists. F: Fluoroscopic image after deployment of two Amplatzer septal occluders. A, anterior; S, superior.
Figure 35.20. ICE imaging during interventional device closure of VSD. A: Intracardiac image of a large ventricular septal defect (arrow) near crux of the heart in a patient with atrioventricular and ventricular great artery discordance. LV, morphologic left ventricle; VSD, ventricular septum; LA, left atrium; RV, morphologic right ventricle. B: Color flow imaging demonstrating a large left-to-right shunt through the VSD. A, anterior; S, superior.
Instantaneous monitoring for catheter-related complications is also possible with the use of ICE. Detection of left-sided thrombus or spontaneous contrast in a cardiac chamber as a precursor to thrombus is facilitated by the use of ICE. Pericardial effusion can easily be visualized by ICE and then promptly treated to prevent complications.
CONGENITAL INTRAOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY
Intraoperative transesophageal echocardiography (IOTEE) has been used in the care of patients with congenital heart defects since the late 1980s. Previous reports have suggested that IOTEE can provide important additional information during intracardiac repair of congenital heart defects. Recommendations for the use of IOTEE have been broad, in part because of the small sample size in prior studies. The preliminary experience with IOTEE during surgery for congenital heart defects at the Mayo Clinic confirmed the accuracy of IOTEE and identified select patients who would benefit from IOTEE based on a small study population of 104 patients. Bezold and colleagues at Texas Children’s Hospital reported a larger experience with IOTEE in 341 patients. They concluded that biplane imaging was far superior to monoplane imaging. IOTEE also seemed to be most beneficial in patients with select diagnoses and surgical procedures in this series. Stevenson concluded that IOTEE had a very low complication rate (about 3%). The largest experience specifically evaluating the utility of intraoperative echocardiography was published by Ungerleider and colleagues, involving over 1000 cases. Their study evaluated both epicardial and transesophageal echocardiography. Disadvantages of epicardial imaging include invasion of the surgical field, limited windows, possible induction of ventricular ectopic beats, and possible transient hypotension. Therefore, IOTEE has become the preferred modality of imaging during surgery for congenital heart defects. IOTEE is useful for recognition of intracardiac air before coming off cardiopulmonary bypass and to provide a routine assessment of postbypass ventricular function.
Figure 35.21. Evaluation of prosthetic perivalvar leak with ICE. A: Intracardiac echocardiography image obtained from the right atrium (RA) in a patient with an LV-to-RA shunt following mitral valve (MV) replacement. This view of the crux of the heart shows the entrance (arrow) of the fistula in the RA. B: Color flow imaging demonstrating a moderate shunt from LV to RA. LA, left atrium; L, left; S, superior.
The multiplane TEE transducer is now the standard probe preferred for all intraoperative TEE studies. The probe consists of a single array of crystals that can be rotated electronically or mechanically around the long axis of the ultrasound beam in an arc of 180 degrees. With rotation of the transducer array, multiplane TEE can obtain a continuum of transverse and longitudinal image planes. Newer adult-size TEE probes have 3- to 7-MHz ultrasound frequency ranges, and some are capable of harmonic imaging as well. Usually with a 64-crystal array, the tips range in size from 12- to 14-mm in diameter (Fig. 35.22). Some IOTEE probes have increased shielding to protect them from the effects of intraoperative electrocautery. Recently developed systems have software capability to obtain live three-dimensional reconstructed images. Unfortunately, pediatric TEE probes have not achieved the degree of sophisticated development as the adult counterparts. The currently available multiplane pediatric TEE probe has a 48-crystal array with a tip diameter of 9 mm (see Fig. 35.22). The frequency agility is from 5 to 7 MHz, and the mobility is limited to movement in one plane. No additional probe shielding from the electrocautery is yet available. As discussed later, we have also used the intracardiac Acunav probe for TEE imaging in small infants (weighing less than 3 kg). More recently, a micro TEE probe has been introduced with a tip diameter of 7.5 mm and a frequency range between 3 and 8 MHz. This probe allows multiplanar imaging in many neonates and young infants. Table 35.1 lists the general weight guidelines we have used for probe selection in infants and children.
Four primary multiplane TEE views can be obtained by rotating the transducer array from 0 to 135 degrees (Fig. 35.23). At 0 degrees, a typical transverse image plane is obtained allowing the typical four-chamber view; at 30 to 45 degrees, transverse plane short-axis images are obtained similar to the TTE parasternal short-axis views of the aortic valve as well as short-axis transgastric images of the left ventricle; 90 degrees provides a typical longitudinal transducer orientation and produces images somewhat oblique to the long axis of the heart; and 120 to 135 degrees provides a true long-axis image of the left ventricular outflow tract analogous to the parasternal long-axis view. Additional images and modifications of typical transverse and longitudinal scan images can also be obtained by typical TEE probe tip manipulation for flexion or right/left angulation (Fig. 35.24). Basic image orientation for TEE imaging has followed the standard image orientation used for transthoracic imaging (Fig. 35.25). The various transverse and longitudinal image planes obtained by probe position, rotation, tip angulation, and image plane angulation have been previously described by Seward et al. and are illustrated in Figures 35.26through 35.32.
Figure 35.22. TEE imaging probes. A: Comparison view of pediatric transesophageal echocardiography probes ranging from the adult-sized multiplane probe, the pediatric biplane probe, the pediatric multiplane probe, and the intracardiac catheter. B: Comparison view of the same probe tips. From left to right: The adult multiplane is 13 mm with 64 elements; the pediatric biplane probe has a 9-mm tip with 64 elements; the pediatric multiplane probe has a 10-mm tip with 48 elements; and the intracardiac echocardiography catheter has a 64-element longitudinal array and is 3.3 mm in diameter.
Figure 35.23. Diagrammatic illustration of multiplane transesophageal echocardiography scan planes corresponding to standard transthoracic short- and long-axis views. The 0-degree transverse orientation corresponds to the standard horizontal plane of biplane transesophageal echocardiography systems, and the 90-degree longitudinal orientation corresponds to the standard vertical plane.
Figure 35.24. TEE imaging planes to evaluate aorta. A: Illustrates a similar comparison of biplane and multiplane transesophageal echocardiography images as they relate to the long axis of the aorta. B: Illustrates the typical transesophageal echocardiography tip deflection used for both biplane and multiplane images to obtain images similar to transthoracic image orientation.
Mayo Clinic Congenital Intraoperative Transesophageal Echocardiography Experience
Randolph et al. reported the Mayo Clinic IOTEE experience with examinations performed in 1002 patients during congenital heart surgery. Impact of IOTEE was assigned prospectively by the surgeon and cardiologist who performed the IOTEE, while the patient was still in the operating suite. The combined major impact rate for the series was 14%. Separate rates of preoperative and postoperative major impact were 9% and 6%, respectively. Of the 22 primary diagnostic categories analyzed, complex right ventricular outflow tract obstruction, defined as lesions requiring more than a valvotomy or transannular patch, had the highest combined impact rate—48% (Table 35.2). Surgical procedures involving younger patients (Table 35.3)and those with VSD repair, valve repair, complex cyanotic disease, or great artery modifications were indications for IOTEE study with the greatest impact.
Figure 35.25. Diagrammatic illustration of comparable transthoracic and transesophageal echocardiography images and appropriate orientation as observed with four-chamber, short-, and long-axis images.
No major complications, defined as death, esophageal or gastric perforations, accidental extubations, upper gastrointestinal bleeding, or endocarditis, occurred as a result of IOTEE during the study period. Minor complications, defined as transient airway compression, problems with ventilation, or compression of the descending aorta by the probe, were observed in 10 patients, or 1% of the study population. Minor complications were most common in patients weighing less than 4 kg. IOTEE was performed in 51 patients weighing less than 4 kg. Minor complications occurred in 6 of these infants, representing a minor complication rate of 12% in this subset of patients.
Some examples of valvular anomalies demonstrated by TEE are exemplified by short-axis TEE images of a bicuspid aortic valve. TEE imaging allows excellent valve imaging to identify the anatomic configuration and degree of commissural fusion as well as leaflet thickening. Figures 35.33 and 35.34 identify the fused leaflets in two examples of bicuspid aortic valve that were significantly stenotic but had little commissural fusion. The stenosis was secondary to eccentricity of the valve leaflets that resulted in a small effective valve orifice. Similarly, Figure 35.35 illustrates aortic valve prolapse and left-to-right shunt in an intraoperative study on a patient with a supracristal VSD. Atrioventricular septal defects (AVSDs) were frequently listed as being impacted by IOTEE. Figure 35.36 illustrates features often observed in AVSDs. Repair of complex congenital defects also ranked high with IOTEE impact. Based on these data and reports from other large institutions, our practice has been to routinely perform IOTEE during intracardiac surgery for all congenital heart defects.
Figure 35.26. Pathologic correlation of images obtained with various multiplane images from 0 degrees to 135 degrees representing horizontal (four-chamber) and longitudinal scan planes. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Figure 35.27. TEE imaging planes obtained from midesophagus. A: tomographic anatomy of the heart at the midesophagus. specimens are presented from the perspective of 0-degree rotation of imaging to 135-degree rotation. the 30- to 45-degree rotation results in short-axis images, while the 120- to 135-degree rotation obtains images similar to parasternal long-axis images. B: composite transesophageal echocardiography images obtained at the various tomographic sections illustrated in A. the image orientation is similar to those obtained with standard transthoracic imaging. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Recently, three-dimensional TEE has become an increasingly powerful tool in assessment of intraoperative and interventional cardiac catheterization procedures. Figure 35.37 illustrates a three-dimensional image obtained in a patient with Ebstein anomaly. Note the large thickened leaflets with a large central area of poor coaptation and multiple defects. Figure 35.38 illustrates a three-dimensional (3D) image of multiple secundum atrial septal defects which would not be easily amenable to device closure. Figure 35.39 and Video 35.5 illustrate 3D guidance of transeptal puncture in preparation for attempted paravalvular leak device closure. Note that the associated color flow imaging is consistent with the large defect outlined by the 3D TEE image. In addition, the 3D images are particularly helpful to guide the interventionalist in placing wires and catheters through the defect in preparation for closure.
Figure 35.28. TEE imaging planes obtained from transgastric position. A: tomographic short- and long-axis anatomic specimens corresponding to transesophageal echocardiography views obtained with transgastric imaging. True short- and long-axis images can be obtained at 45- and 135-degree rotation, respectively. B: corresponding transesophageal echocardiography images obtained from the transgastric position illustrating short-axis images at 45 degrees and long-axis images obtained at 135-degree array rotation. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Figure 35.29. TEE imaging from the longitudinal scan plane at the midesophagus. A: Midesophageal longitudinal tomographic anatomic sections cut to correspond to longitudinal plane echocardiographic images obtained by rotating the transesophageal echocardiography probe from the patient’s right to left. B: A series of longitudinal echocardiographic views obtained from the midesophagus by rotating the transesophageal echocardiography probe while maintaining the array at 90 degrees throughout the probe rotation to the patient’s left. The first image is obtained on the patient’s right side illustrating a long-axis bicaval view of the right atrium. With progressive probe rotation, subsequent images of the proximal ascending aorta, the right ventricular outflow tract, and finally a two-chamber view of the left ventricle are obtained. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Figure 35.30. TEE imaging of LV long axis. Transesophageal echocardiography images obtained from the midesophagus illustrating the standard longitudinal images at 90 degrees and movement to typical LV long-axis images obtained by rotating the crystal array to 135 degrees. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Figure 35.31. TEE imaging of LV short axis. Transesophageal echocardiography images obtained from the transgastric position demonstrating a series of short-axis images obtained with the crystal array at 0 degree and by retroflexing the probe to obtain short-axis images closer to the apex of the left ventricle. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Figure 35.32. TEE imaging at the cardiac base. A: Anatomic cross section of the base of the heart just above the level of the aortic valve demonstrating the proximity of the esophagus to the left atrium and cardiac structures. The cross section illustrates the type of aortic valve image observed in the standard transesophageal echocardiography short-axis image. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Intraoperative Transesophageal Echocardiography Using the Intracardiac Echocardiography Probe
The ICE probe has also been used for transesophageal imaging in small infants during congenital cardiac surgery. The small size of this probe facilitates its placement in children weighing less than 3 kg. To date, our center has performed approximately 100 studies in children less than 3 kg with this probe. Initial reports of the TEE use of the ICE probe in animal models and small children have been encouraging. Bruce and colleagues demonstrated in 2002 that the probe could successfully be used in a group of 17 infants who weighed between 2.1 and 5.6 kg. No major complications were reported. In 13 of 22 studies performed in that study, the standard biplane pediatric TEE probe could not be advanced into the esophagus due to the patient’s small size. Therefore, TEE imaging would not have been performed if the ICE probe was unavailable. High-quality two-dimensional and Doppler images of the descending thoracic aorta (Fig. 35.40, both ventricles (Fig. 35.41)), and apical and outlet ventricular septa are obtained with the ICE probe. In addition, the systemic and pulmonary venous connections to the atria and the atrial septum are adequately visualized with this probe.
The major disadvantage of the ICE probe is that it is monoplane. Longitudinal imaging is effective, but the crux of the heart and the inlet ventricular septum are not adequately visualized. This probe has not been suitable during repair of AVSDs. However, these defects are rarely repaired in the newborn period. Transgastric imaging is also suboptimal with this probe because the orientation of the phased-array pallet does not permit articulation near the probe tip. To avoid thermal injury, it is recommended that imaging time be succinct and that the probe be powered only when in use. While there are technical limitations to performing TEE with this probe, it provides reliable and adequate imaging in patients who otherwise would not be able to have TEE performed during cardiac surgery.
Figure 35.33. Transesophageal echocardiographic short-axis image of bicuspid aortic valve showing a very eccentric valve orifice with a raphe (fused commissure) between the right and left aortic cusps. There is some nodular thickening at the raphe but no other evidence of commissural fusion. The orifice commissure is marked by the two x’s. R, right cusp; L, left cusp; N, noncoronary cusp; A, anterior; L, left; AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atrial appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea; VS, ventricular septum.
Figure 35.34. Transesophageal echocardiographic short-axis images of bicuspid aortic valve. The aortic orifice is fairly symmetric and opens widely without commissural fusion. There is mild leaflet thickening. AS, atrial septum; AW, anterior LV wall; AL, anterolateral papillary muscle; B, bronchus; CS, coronary sinus; E, esophagus; IVC, inferior vena cava; LAA, left atria appendage; LVO, LV outflow; L, left coronary cusp; MPA, main pulmonary artery; N, noncoronary cusp; PM, posteromedial papillary muscle; PV, pulmonary valve; Pul V, pulmonary veins; R, right coronary cusp; RAA, right atrial appendage; RVO, RV outflow; SVC, superior vena cava; T, trachea VS, ventricular septum.
Figure 35.35. Aortic CUSP prolapse. A: Intraoperative transesophageal echocardiographic long-axis image showing a subarterial (“supracristal”) ventricular septal defect with a prolapsed aortic cusp. The defect margins are marked with +s. B: Color flow imaging during a systolic frame showing a left-to-right shunt through the defect. RV, right ventricle; LV, left ventricle; Ao, aorta; L, longitudinal plane; A, anterior; S, superior; MV, mitral valve.
Figure 35.36. TEE imaging in AVSD. A: Transgastric intraoperative transesophageal echocardiographic LV short-axis image showing a large cleft in the anterior mitral leaflet in a patient with an ostium primum atrial septal defect (ASD) (partial AV septal defect). B: Transverse (four-chamber) views of partial AV septal defect showing the ASD and both atrioventricular valves that are aligned on the same horizontal plane. The cleft in the anterior mitral leaflet results in significant regurgitation (MR) into the left atrium (LA). RV, right ventricle; LV, left ventricle; AS, atrial septum; VS, ventricular septum; S, superior; L, left.
Figure 35.37 and Video 35.3. TEE imaging of multiple secundum ASDs. Right atrial view of 3D reconstruction of multiple secundum ASDs during intraoperative TEE. The larger defect is divided by a thin strand of atrial septum. A smaller fenestrated defect is located (arrow) in the inferior medial portion of the atrial septum.
Figure 33.38 and Video 35.4. Live 3D TEE image of tricuspid valve in patient with Ebstein anomaly. The tricuspid valve anterior leaflet is thickened (arrowhead) and several fenestrations are also noted (arrow).
Figure 35.39 and Videos 35.5 and 35.6. Interventional 3D TEE imaging. A: 3D TEE guidance of transseptal atrial septal puncture. The transeptal needle (arrow) punctures the septum primum (SP) just below the limbus (L) of the fossa ovalis. Live images seen in Video 35.5. B: 3D TEE reconstruction of the left atrial view of a mechanical mitral valve prosthesis with a large paravalvular leak present delimited by the arrows. It is elliptical and located in the posterior, medial aspect of the valve. The valve discs (D) are identified. Live images are seen in Video 35.6. C: 3D color flow image of the paravalvular regurgitant jet (arrow).
Figure 35.40. TEE imaging of descending aorta with ICE probe. A: Transesophageal echocardiographic image with the intracardiac echocardiography catheter obtained in a small infant with critical discrete coarctation (arrow) of the aorta (Ao). B: Color flow imaging demonstrates aliased flow through the obstruction with a 4 m/s velocity recorded with continuous-wave Doppler.
Figure 35.41. TEE imaging of truncus arteriosus with ICE probe. A: Transesophageal echocardiography image with the intracardiac echocardiography catheter obtained in an infant after repair of truncus arteriosus. A patch (asterisk) is observed closing the ventricular septal defect between the right ventricle (RV) and the left ventricle (LV). B: Color flow imaging demonstrated an intact patch. LA, left atrium; Ao, aorta.
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1.What is the AcunavTM intracardiac echo probe?
A.A mechanical system allowing accurate demonstration of 3-D intracardiac images.
B.A 48-element phased array system which allows 2-D imaging with Doppler capability.
C.A 64 element phased array system which allows 2-D imaging at multiple frequencies.
D.A mechanical system allowing 2-D imaging with Doppler capability.
2.What occurs with intracardiac imaging?
A.The probe must be placed as close to the structure as possible because of the limited far distance field capability.
B.The probe can be manipulated with rotational and multiple directional flexion capability.
C.Only long axis imaging is possible
D.The pulmonary veins are usually not well visualized.
3.Which of the following refers to ICE imaging?
A.Results in improved patient comfort when compared with TEE
B.Requires general anesthesia due to need for vascular access
C.Requires IRB approval for use
D.Requires multiple operators to provide appropriate images
4.Which of the following refers to ICE imaging?
A.Has been useful to guide coronary angiography
B.Guides needle placement for precise and safe transseptal puncture
C.Does not allow for balloon sizing of atrial septal defect
D.Is not appropriate for electrophysiologic procedures because of the risk of esophageal perforation
5.The intracardiac echo probe:
A.should not be advanced across an atrial septal defect.
B.may be used to terminate atrial fibrillation.
C.should not be placed within the ventricular cavity due to concerns for perforation.
D.allows imaging of most intracardiac structures.
A.is not possible with the ICE probes that are currently available.
B.is only possible with TEE.
C.currently has limited functionality for ICE imaging.
D.is not possible in the operating room.
A.has been used in the care of patients with congenital heart defects since the late 1980s.
B.is only applicable to cardiac surgical procedures.
C.is often utilized without general anesthesia.
D.has never been associated with esophageal injury.
A.is only available on adult TEE probes.
B.has been associated with significant incidence of esophageal injury.
C.this transducer is now the standard probe preferred for all intraoperative TEE studies.
D.consists of a single array of crystals that can be rotated electronically or mechanically around the long axis of the ultrasound beam in an arc of 360 degrees.
A.provides three-dimensional (3-D) images of multiple secundum atrial septal defects.
B.cannot be used in the catheterization laboratory because of interference from x-ray imaging.
C.is not affected by electrocautery interference.
D.provides superior imaging of structures immediately below the chest wall.
A.should be used selectively in congenital cardiac surgery because of the limited cost benefit ratio.
B.generally is only used preoperatively to correct previous inaccurate diagnoses.
C.can be used to recognize intracardiac thrombus.
D.is not amenable to recognition of intracardiac air.
1.Answer: C. The Acunav ICE probe is a 64-element array. It is a phased array system, not a mechanical array system.
2.Answer: B. The ICE probe can be rotated and flexed directionally. It is not limited to one plane. The pulmonary veins are easily identified by ICE imaging.
3.Answer: A. ICE imaging is less painful than TEE and is fully approved for clinical use. TEE often requires significant sedation or general anesthesia.
4.Answer: B. ICE is useful to guide transeptal puncture, ASD sizing, and EP procedures. It is not used to facilitate coronary angiography.
5.Answer: D. While ICE imaging has occasionally produced atrial arrhythmias, ICE imaging does allow visualization of most cardiac structures. The probe can be positioned in the ventricle or across an ASD.
6.Answer: C. 3D imaging is now possible with new ICE probes but is limited currently to a 20 degree sector with the ICE probe.
7.Answer: A. Intraoperative TEE has been used since the 1980s (as cited in the references for TEE).
8.Answer: C. Multiplanar TEE is now available on both pediatric and adult probes.
9.Answer: A. TEE is excellent to show 3-D images of ASDs but is less able to define anterior structures in the far field. It is typically very sensitive to the electrocautery interference.
10.Answer: C. Intraoperative TEE definitely can be used to see intracardiac thrombus routinely, and is currently used in most open heart procedures for congenital heart disease.