Recommendations for Transesophageal Echocardiographic Screening in Transcatheter Left Atrial Appendage Exclusion, Interatrial Septum, and Interventricular Septum Interventions: Insights for the Cardiothoracic Anesthesiologist.

IN THE American Society of Echocardiography's recently published guidelines on structural heart interventions titled Recommended Standards for the Performance of Transesophageal Echocardiographic Screening for Structural Heart Intervention, Hahn et al. described several echocardiographic protocols for the pre-procedural screening of structural targets.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar As part of the multidisciplinary Structural Heart Team, cardiothoracic anesthesiologists have an expanding footprint as proceduralists, echocardiographers, and experts in the management of complex cardiovascular physiology. In the framework of the rapidly increasing rate at which these procedures are being performed, it is important to examine these guidelines in the context of this specialty.2Mack M Carroll JD Thourani V et al.Transcatheter mitral valve therapy in the United States: A report from the STS-ACC TVT Registry.J Am Coll Cardiol. 2021; 78: 2326-2353Crossref PubMed Scopus (54) Google Scholar This editorial aims to discuss the preprocedural imaging techniques and anesthetic implications for the evaluation of the left atrial appendage (LAA), interatrial septum (IAS), and interventricular septum (IVS). The LAA is a tubular structure derived from the primitive atrium during embryonic development and is morphologically distinct from the left atrium (LA). Given the high propensity of clot formation within the LAA in patients with atrial fibrillation, minimally invasive methods for excluding this vestigial structure are becoming increasingly popular. Evaluation of the LAA for percutaneous occlusion or exclusion requires an in-depth transesophageal echocardiographic (TEE) assessment of this structure. The identification of appendage morphology (e.g., windsock, chicken wing, broccoli, and cactus), the number and location of accessory lobes, and the measurements of landing zone diameters and appendage depth are critical for device selection.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar This assessment is performed at the level of the mid-esophagus at 0°, 45°, 90°, and 135° and is often augmented with biplane imaging to assist with developing a 3-dimensional (3D) understanding of the appendage size, shape, and depth. The use of advanced imaging software, such as multiplanar reconstruction, is also recommended, as it allows the echocardiographer to manipulate imaging planes to display the anteroposterior, septal-lateral, and landing zone axes simultaneously, which may be particularly helpful in appendages with ovoid ostia.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar,3Wollborn J Schuler A Sheu RD et al.Real-time multiplanar reconstruction imaging using 3-dimensional transesophageal echocardiography in structural heart interventions.J Cardiothorac Vasc Anesth. 2023; 37: 570-581Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar There are 3 main devices currently marketed for LAA exclusion in the United States—2 endocardial plugging devices (Amplatzer Amulet [Abbott Laboratories] and Watchman/Watchman FLX [Boston Scientific]) and 1 epicardial LAA ligation system (Lariat/Lariat+ [SentreHEART]).4Musat D updates Mittal S.LARIAT trial J Atr Fibrillation. 2018; 11: 1806Crossref PubMed Scopus (5) Google Scholar The Watchman and newer version, Watchman FLX, each have the following 5 sizes: 21, 24, 27, 30, and 33 mm, and 20, 24, 27, 31, and 35 mm, respectively. The Watchman FLX can accommodate a wider range of LAA ostium sizes (14 mm up to 31.5 mm) and is especially useful for LAAs with shallower depths due to a 20% shorter length compared to the preceding version.5Joury A Englert 3rd, JAR Bernard M et al.Watchman FLX implantation for challenging left atrial appendage anatomy: Case-based discussion.Curr Probl Cardiol. 2022; 47101266Crossref PubMed Scopus (1) Google Scholar Importantly, when sizing the Watchman and Watchman FLX, one must consider an 8% to 20% and 10% to 27% device compression, respectively, to ensure an appropriate fit and reduce the incidence of paravalvular leaks and maximize device stability.6Grygier M Olasinska-Wisniewska A Araszkiewicz A et al.The Watchman FLX - a new device for left atrial appendage occlusion - design, potential benefits and first clinical experience.Postepy Kardiol Interwencyjnej. 2017; 13: 62-66PubMed Google Scholar In contrast, the Lariat and Lariat+ use an epicardial snare to ligate the LAA and can be used to exclude much larger LAA with diameters up to 45 mm.4Musat D updates Mittal S.LARIAT trial J Atr Fibrillation. 2018; 11: 1806Crossref PubMed Scopus (5) Google Scholar Thus, it is important to know how appendage sizing and morphology impact device selection. Despite providing a detailed set of recommendations for imaging and sizing of the LAA, several questions remain unanswered regarding under what conditions these measurements should be obtained and how these measurements should be applied to device selection. As early as 2015, it has been shown that the administration of an intravenous fluid bolus (500-1000 mL) significantly increases LAA dimensions.7Spencer RJ DeJong P Fahmy P et al.Changes in left atrial appendage dimensions following volume loading during percutaneous left atrial appendage closure.JACC Cardiovasc Interv. 2015; 8: 1935-1941Crossref PubMed Scopus (68) Google Scholar Most recently, in 2021, Freitas-Ferraz et al. demonstrated that a 500 mL normal saline fluid bolus increased an LAA landing zone diameter and depth by as much as 2.5 mm and 3.6 mm, respectively, without an increase in complication rate associated with fluid administration.8Freitas-Ferraz AB Bernier M O'Connor K et al.Safety and effects of volume loading during transesophageal echocardiography in the pre-procedural work-up for left atrial appendage closure.Cardiovasc Ultrasound. 2021; 19: 3Crossref PubMed Scopus (3) Google Scholar Knowing whether or not the patient received this volume expansion during the pre-procedural echocardiographic assessment or whether it was contraindicated due to patient-specific factors, such as elevated left atrial pressures, heart failure, or pulmonary edema, is important because this can affect device sizing and selection. The IAS is a complex structure with several distinct components, including the septum primum, septum secundum, fossa ovalis, and atrioventricular septum. Communication of flow across the septum at each of these locations can cause an unbalanced ratio of pulmonary to systemic blood flow (Qp:Qs) and have important implications on the feasibility of percutaneous closure. A thorough echocardiographic assessment of the IAS and associated structures is therefore imperative to determine if these communications are amenable to percutaneous closure and assist with anesthetic planning should closure be attempted. An echocardiographic evaluation of the IAS must take place at multiple levels of the esophagus to ensure a comprehensive assessment. In the upper esophageal view, a stepwise scan from 0° to 45° in 15° increments is recommended to visualize the superior aspect of the septum. The most common defects seen at this location include superiorly located secundum and sinus venosus defects.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar Additionally, one can image a patent foramen ovale (PFO) tunnel and an en-face view of a coronary sinus defect, seen posterior to the LA at 90 and 120°, respectively.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar,9Sun T Fei HW Huang HL et al.Transesophageal echocardiography for coronary sinus imaging in partially unroofed coronary sinus.Echocardiography. 2014; 31: 74-82Crossref PubMed Scopus (13) Google Scholar At the mid-esophagus, a similar sweeping motion from 0° to 110° will allow for the visualization of most other aspects of the IAS. Between 0° and 30°, the posterior and atrioventricular valve rims are imaged typically where ostium primum and coronary sinus defects may be seen. Increasing the angle from 45° to 60° will bring the anterior and/or superior aortic rim into view, followed by the bicaval view at 90° to 120°, which will image both the superior and inferior rims.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar Importantly, in their imaging protocol, Hahn et al. introduced the deep esophageal (DE) view as a new position for evaluating the IAS. Advancing the TEE probe deep to the mid-esophageal station with mild flexion should bring the inferior rim of the IAS into view. The DE position assists with evaluating this segment of the IAS, which is known to be the most challenging and often the most critical. It has been shown that deficiency in the inferior and/or posterior rim of secundum septal defects is associated with device failure and procedural complications, including device embolization and complete atrioventricular block.10Amedro P Bayburt S Assaidi A et al.Should transcatheter closure of atrial septal defects with inferior-posterior deficient rim still be attempted?.J Thorac Dis. 2019; 11: 708-716Crossref PubMed Scopus (18) Google Scholar Additionally, the DE probe position is excellent for imaging the roof of the coronary sinus, which can be helpful in the diagnosis of a left persistent superior vena cava and identifying additional structures seen within the right atrium (RA), such as a Chiari network.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar Once a thorough 2D assessment of the IAS has been performed, a 3D evaluation is also recommended. Considering that anatomic defects may cross multiple 2D imaging planes, visualizing the IAS in 3D may provide additional information about the proximity of the defects to surrounding cardiac structures.11Song BG Park SW Lee SC et al.Real-time 3D TEE for multiperforated interatrial septum.JACC Cardiovasc Imaging. 2010; 3: 1199Crossref PubMed Scopus (7) Google Scholar Although Hahn et al. did not explicitly discuss a standardized orientation of the IAS during 3D analysis, they referenced the 2015 American Society of Echocardiography's guidelines for the assessment of atrial septal defects and PFOs, which discussed this in detail. Silvestry et al. recommended that when the IAS is viewed from the LA, the right upper pulmonary vein should be in the 1 o'clock position, and when it is viewed from the RA, the SVC should be in the 11 o'clock position.12Silvestry FE Cohen MS Armsby LB et al.Guidelines for the echocardiographic assessment of atrial septal defect and patent foramen ovale: From the American Society of Echocardiography and Society for Cardiac Angiography and Interventions.J Am Soc Echocardiogr. 2015; 28: 910-958Abstract Full Text Full Text PDF PubMed Scopus (313) Google Scholar This method of orientating the IAS is critical when reviewing and comparing 3D IAS reconstructions and should become standard practice similar to how the “en-face” or “surgical view” view has become standard for the mitral valve.13Mahmood F Warraich HJ Shahul S et al.En face view of the mitral valve: Definition and acquisition.Anesth Analg. 2012; 115: 779-784Crossref PubMed Scopus (16) Google Scholar In addition to the increasing utility of 3D echocardiography for assessing the IAS, intracardiac echocardiography (ICE) for procedural guidance of PFO and ASD closures is becoming increasingly common. Most frequently used for electrophysiology procedures during transseptal puncture and pulmonary vein localization, ICE has excellent imaging capabilities of the IAS and has shown to be an effective imaging modality for diagnosing IAS defects and guiding percutaneous closure devices.14Kavvouras C Vavuranakis M Vaina S et al.Intracardiac echocardiography for percutaneous patent foramen ovale and atrial septal defect occlusion.Herz. 2019; 44: 445-449Crossref PubMed Scopus (12) Google Scholar Similar to how transcatheter aortic valve replacements previously were performed exclusively under general anesthesia with TEE guidance and are now predominantly performed under monitored anesthesia care (MAC) with fluoroscopic guidance, IAS defect closures increasingly may be performed similarly under MAC and ICE. Although Hahn et al. did not discuss the use of ICE and its application to imaging for structural interventions, it is an important modality that likely will become more frequently used for these procedures. It has therefore been suggested by leaders in the echocardiographic space that cardiothoracic anesthesiologists should learn how to perform and interpret ICE to maintain a valued role as expert imagers within the multidisciplinary Heart Team.15Belani K Mahmood F Ortoleva J. Beyond the third dimension: Intracardiac echocardiography-the next frontier for cardiac anesthesiologists.J Cardiothorac Vasc Anesth. 2021; 35: 979-981Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar The IVS is another complex cardiac structure that is largely made up of the muscular septum, which arises from the apex of the developing heart, fusing with the smaller, membranous portion, which extends down from the septum intermedium around week 5 of embryonic development.16Triposkiadis F Xanthopoulos A Boudoulas KD et al.The interventricular septum: Structure, function, dysfunction, and diseases.J Clin Med. 2022; 11: 3227Crossref PubMed Scopus (2) Google Scholar Although ventricular septal defects (VSDs) can occur anywhere within the septum, only 2 out of the 5 types of congenital types of VSDs, membranous and muscular VSDs, can be closed via a percutaneous device because of the presence of circumferential rims.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar Regarding acquired VSDs, which include septal rupture after myocardial infarction and traumatic disruption, which typically occur after penetrating trauma, transcatheter closure is an alternative to surgical closure if the patient is determined too high risk for open repair. Due to the various locations where both congenital and acquired VSDs can occur, obtaining a thorough echocardiographic evaluation using 2D, 3D, color flow, and continuous wave Doppler is important to determine if the defect is amenable to percutaneous closure. Specifically, in patients with congenital VSDs, assessing for pulmonary hypertension using the tricuspid regurgitant envelope is recommended at the time of pre-procedural image acquisition. This will help determine if the patient should be referred to an adult congenital heart center of excellence out of concern for Eisenmenger Syndrome, in which case VSD closure would not be recommended.1Hahn RT Saric M Faletra FF et al.Recommended standards for the performance of transesophageal echocardiographic screening for structural heart intervention: From the American Society of Echocardiography.J Am Soc Echocardiogr. 2022; 35: 1-76Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar At the mid-esophageal position at 0°, gentle anteflexion and retroflexion allow the echocardiographer to fan through the IVS from anterior to posterior to assess for basilar, middle, or apical muscular defects. In this view, the Doppler beam is nearly perpendicular to the flow direction; thus, velocities and gradients should not be attempted. In contrast, increasing the omniplane angle to visualize the aortic valve in the short-axis view (45°-60°) will not only optimize a view suitable for measuring gradients through the tricuspid valve to estimate pulmonary pressures but also help visualize 2 distinct VSDs. Adjacent to the septal leaflet of the tricuspid valve, at the 7 or 8 o'clock position on the aortic valve in the short-axis view, membranous VSDs may be best visualized. Membranous VSDs also may be associated with aneurysmal tissue of the membranous septum and the tricuspid valve, causing increased tricuspid regurgitation or even left ventricle (LV) to RA shunting, which is known as a Gerbode defect. Thus, it is important to carefully characterize flow patterns and shunt direction to avoid overestimating pulmonary pressures.17Garg R Garcia R Cubeddu RJ. Gerbode defect misinterpreted as pulmonary hypertension.J Cardiol Cases. 2013; 7: e34-e36Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar Adjacent to the pulmonic valve at the 5 o'clock position on the aortic valve, subpulmonic VSDs, the least common congenital VSD, may be seen. Interestingly, both subpulmonic and membranous VSDs are associated with aortic valve prolapse, and if both the aortic valve and IVS defects meet the criteria for intervention, the patient may be more suitable for open surgical repair. Lastly, the transgastric windows are critical for identifying and evaluating most congenital and acquired muscular septal defects. Scanning from the base to the apex at 15 increments is recommended to ensure a thorough assessment; the presence of adequate surrounding tissue and the diameter of the lesion will determine whether percutaneous closure is feasible. Importantly, the IVS contains a significant portion of the cardiac conduction system, which can be affected significantly by acquired defects within the IVS.16Triposkiadis F Xanthopoulos A Boudoulas KD et al.The interventricular septum: Structure, function, dysfunction, and diseases.J Clin Med. 2022; 11: 3227Crossref PubMed Scopus (2) Google Scholar Acquired VSDs may cause acute conduction abnormalities, and identifying specific bundle-branch blocks or fascicular blocks may inform defect location and assist with managing these potentially unstable patients in the operating room. Similarly, cardiac anesthesiologists routinely evaluate patients with hypertrophic cardiomyopathy for post-surgical iatrogenic VSDs after septal myectomies, which also can result in conduction defects. Although rare, post-myectomy VSDs have an incidence of approximately 1% and occur either due to excessive resection of the IVS or impaired septal blood flow, causing an infarction.18Raheja S Shetty V Shanmugasundaram B et al.A novel surgical technique to address post-septal myectomy ventricular septal defect.Ann Thorac Surg. 2022; 113: e63-e66Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar,19Parsons C Zhao CB Huang J. Closure of an iatrogenic ventricular septal defect using a hybrid approach and echocardiographic guidance.Ann Card Anaesth. 2020; 23: 212-215Crossref PubMed Scopus (4) Google Scholar These defects may be located in the membranous or muscular septum and should not be mistaken for septal perforator branches at the resection site. One can distinguish between septal perforators and an iatrogenic VSD by assessing the direction and timing of the blood flow—septal perforator flow will be seen into the LV during diastole, whereas VSD flow will be seen exiting the LV during systole.20Ralph-Edwards A Vanderlaan RD Bajona P. Transaortic septal myectomy: Techniques and pitfalls.Ann Cardiothorac Surg. 2017; 6: 410-415Crossref PubMed Scopus (13) Google Scholar The optimal views for assessing for a post-septal myectomy VSD are the mid-esophageal aortic valve long-axis and deep transgastric aortic valve long-axis views, which allow for the visualization of both the muscular and membranous septum with minimal rotation of the TEE probe. Although preprocedural structural echocardiographic assessments provide an enormous amount of valuable information for interventionalists and cardiac anesthesiologists regarding relevant anatomy, hemodynamic severity, and the mechanism of a valvular or structural defect, the guidelines do not recommend the acquisition of basic standard views to provide a context in which these structural lesions exist. Important information such as biventricular function and concomitant valvulopathies or cardiomyopathies have significant anesthetic implications regarding whether one performs MAC versus a general anesthetic or whether invasive monitoring, such as arterial or central venous access, is used. Additionally, it is important to be mindful of areas in which the guidelines are incomplete, such as volume loading the LA before obtaining LAA measurements for device occlusion or exclusion. As the number of transcatheter procedures increases and the footprint of cardiac anesthesiologists expands, it is vital that cardiac anesthesiologists not only stay up to date on the latest imaging recommendations but also understand their limitations with respect to this specialty if wishing to maintain an integral role in the Structural Heart Team. P.J.N. is a consultant for Medtronic.