Transesophageal Echocardiography (TEE)

Language quoted from Centers for Medicare and Medicaid Services (CMS). National Coverage Determinations (NCDs) and coverage provisions in interpretive manuals is italicized throughout the policy. NCDs and coverage provisions in interpretive manuals are not subject to the Local Coverage Determination (LCD) Review Process (42 CFR 405.860[b] and 42 CFR 426 [Subpart D]). In addition, an administrative law judge may not review an NCD. See Section 1869(f)(1)(A)(i) of the Social Security Act.

Unless otherwise specified, italicized text represents quotation from one or more of the following CMS sources:

Title XVIII of the Social Security Act (SSA):

Section 1862(a)(1)(A) excludes expenses incurred for items or services which are not reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member.

Section 1833(e) prohibits Medicare payment for any claim which lacks the necessary information to process the claim.

Section 1862(a)(7) of Title XVIII of the Social Security Act excludes routine physical examination, unless otherwise covered by statute.

Code of Federal Regulations:

42 CFR, Section 410.32, indicates that diagnostic tests may only be ordered by the treating physician (or other treating practitioner acting within the scope of his or her license and Medicare requirements) and the results must be used in the management of the patient.

42 CFR, Section 410.33c, describes qualifications required for non-physician practitioners used by an IDTF.

CMS Publications:

CMS Publication 100-02, Medicare Coverage Issues Manual, Chapter 15:

80 Requirements for Diagnostic X-Ray, Diagnostic Laboratory, and Other Diagnostic Tests

CMS Publication 100-04, Medicare Claims Processing Manual, Chapter 9:

100 General Billing Requirements

CMS Publication 100-04, Medicare Claims Processing Manual, Chapter 12:

30.4 Cardiovascular System (Codes 92950-93799)

CMS Internet-Only Manual (IOM), Publication 100-04, Medicare Claims Processing Manual, Chapter 13:

20 Payment conditions for radiology services

National CCI Manual, version 13.3, Chapter II: CCI editing for anesthesia services; accessible at http://www.cms.hhs.gov/NationalCorrectCodInitEd/

Abstract:

Transesophageal echocardiography (TEE) is performed by placing the ultrasound transducer in the esophagus achieving closer proximity to the anatomical structures of the heart, and improved image quality. This is particularly useful for posterior structures, such as the pulmonary veins, left atrium, and mitral valve. It also provides better visualization of the aortic root, valve and the ascending and descending aorta and arch.

The placement of the probe is relatively invasive, with risk of laryngeal or esophageal tears, and requires conscious sedation. TEE is performed by a physician echocardiographer trained to interpret the data on-line. TEE is frequently not medically necessary when a technically adequate TTE has been performed. If TTE is technically inadequate, or demonstrates pathology but does not provide adequate data for definitive therapeutic decision, TEE may be considered appropriate. Furthermore, there are a number of medical conditions for which TEE is preferred over transthoracic echocardiography. Medically necessary TEE is expected to provide information not available with TTE, and to significantly contribute to management decisions regarding treatment of the patient.

This policy defines clinical pathophysiologic states for which this contractor will provide coverage for TEE examinations. Covered conditions reflect those for which there is authoritative literature to support clinical utilization.

Indications:

Doppler Color Flow Velocity Mapping:

• Spectral Doppler echocardiography and Doppler color flow-velocity mapping (93320, 93321, 93325) may be necessary in addition to an echocardiogram when the examination could contribute significant information to the patient's condition or treatment plan (For dates of service on or after 01/01/2009, code 93306 should be used when Doppler is combined with a complete echocardiogram). Typically, Doppler is indicated in the evaluation of some heart murmurs, valvular problems, shunts, suspected congenital heart disease, complications of myocardial infarction, or cardiomyopathy. Doppler should be medically necessary for the evaluation and management of the patient.
• "Color/spectral Doppler may not be useful or appropriate in certain relatively small and well-defined patient populations when there is a recent comprehensive examination and the test is being ordered for re-evaluation of a limited problem." (ASE comment).
• The use of the Doppler is inherent in the ultrasonic cardiac evaluation. However, if the test reports fail to document the use of this technique to assess these structures and function (e.g., measurement of valvular insufficiency or stenosis, myocardial diastolic function, etc. as described by the ASE), or if the medical records fail to document that the examination was "clinically necessary" (e.g., follow-up of pericardial effusion size) then the Doppler portion of the test may be considered medically unnecessary and denied.
• Mitral valve disease:
  TEE is indicated for the following:
  • When needed to assess the etiology of mitral regurgitation
  • When needed to assist in the decision making: mitral valve repair vs. replacement
  • Endocarditis:
    TEE is indicated for the following:
    • When the suspicion of endocarditis is high (persistent febrile state, negative cultures, preexistent valvular pathology) and TTE does not document endocarditis. TEE may define small vegetative masses and more completely delineate local complications (e.g., ring abscesses, aneurysm, fistulae).
    • Re-evaluation in complex endocarditis;
    • Evaluation of bacteremia without known source; and
    • Evaluation of suspected or actual prosthetic valve endocarditis otherwise obscured because of reverberations and other image artifacts related to mechanical or other non-native valves during TTE.
    • Valvular Prostheses (mechanical and bioprostheses):
    • TEE is indicated in the evaluation of suspected prosthetic valve dysfunction when therapeutic decisions are critical and TTE is inconclusive and/or when the left atrium must be well-visualized. TEE is not routinely indicated in all patients with prosthetic valves.
    • Suspected Cardiac Thrombi and Emboli:
      TEE is indicated for the following:
      • Evaluation of the left atrium and atrial appendage for clot, when clot is not visualized on TTE;
      • Evaluation for an ASD, patent foramen ovale or atrial septal aneurysm with clot; and
      • Evaluation of the mitral valve in patients with a history of emboli.
      • Cardiac/Pericardial Masses and Other Pericardial Disease:
        TTE and TEE have comparable sensitivity in the assessment of right heart masses. Therefore, TEE is indicated for the following:
        • Visualization of left atrial masses when needed to provide therapeutic direction (cystic vs. solid, attachment, infiltration);
        • When cardiac mass lesions (including tumors on cardiac valves) are suspect and cannot be visualized on TTE, and TEE is needed for development of a management strategy; and
        • To assess pericardial effusion when surface studies do not provide adequate information. "The risk of pericardiocentesis may be reduced by the use of echocardiographic guidance and monitoring of needle aspiration, particularly for loculated or small effusions." (ACC/AHA/ASE 2003 Guideline Update, pg. 39).
        • Aortic Pathological Conditions and Diseases of the Great Vessels:
        • TEE may be indicated when adequate visualization of the aortic root is not sufficient with TTE.
        • TEE may be indicated for identification of aortic dissection, aortic ulceration, atherosclerotic plaque, and mural thrombotic material.
        • TEE has a particularly high degree of sensitivity and specificity for aortic dissection. TEE is the technique that is indicated in examination of the entire aorta, especially in emergency situations.
        • Because descending thoracic aortic aneurysms are difficult to visualize using TTE, TEE is recommended for this condition.
        • Visualization of the superior vena cava and diagnosing various congenital and acquired abnormalities, such as vena caval thrombosis;
        • Visualization of the proximal inferior vena cava, vena caval dilation and detection of thrombosis or extension of tumors from the inferior vena cava to the right-heart chambers;
        • Visualization of all four pulmonary veins; and
        • Evaluation of the heart and great vessels following blunt trauma to the chest (e.g., rupture or transsection of the aorta, acute dissection, hematoma, etc.)
        • Congenital Heart Disease:
          TEE is indicated for the following:
          • Patients with congenital heart disease postoperatively where fibrosis, echo opaque patches and prostheses, inadequate penetration, and acoustical shadowing can result in incomplete TTE data;
          • Patients in which TTE is technically inadequate or anatomic definition is incomplete;
          • Patients in whom a more precise definition of atrial, outflow tract and proximal pulmonary vascular anomalies by TEE can be critical to management strategies; and
          • To assess complications of congenital heart surgery, visualization of shunt flow across atrial-septal defects, guidance of clamshell device to close atrial-septal defects, diagnosis of cor triatriatum, and detection of pulmonary valve abnormalities.
          • Critically Ill Patients:
            TEE is indicated for the following:
            • Management of the critically ill patient when TTE is otherwise contraindicated (e.g., chest or other major trauma) or inadequate (e.g., patient on a ventilator or with COPD, or in postoperative patients who are unable to be positioned for TTE);
            • Patients with persistent hypoxemia having suspected right-to-left shunt;
            • Patients with complications of myocardial infarction (ruptured septum, papillary muscle, or free wall);
            • Hemodynamically unstable patients in whom TTE images are suboptimal;
            • Evaluation of brain-dead patients being considered as cardiac donors; and
            • Persistent unexplained fever when endocarditis or myocardial abscess is suspected and TTE is non-diagnostic.
            • Interventional and Surgical TEE:
              TEE is indicated for the following:
              • Guidance during percutaneous cardiac interventions such as during the creation of shunts, placement of septation devices, valvuloplasty procedures, endomyocardial biopsy, electrophysiologic studies/procedures, placement of septal or atrial appendage occluders or during percutaneous valve replacement;
              • Intraoperative evaluation to assess prosthetic or repaired/reconstructed valve function, or the integrity/function of complex congenital heart repairs;
              • Intraoperative evaluation to assess the integrity of the cardiopulmonary circulation in patients during lung or heart-lung transplants; and
              • Intraoperative assessment for presence and/or severity of outflow tract obstruction or presence/repair of an intracardiac shunt;
              • Intraoperative assessment of wall motion abnormalities in the case of acute deterioration in the patient's status, once the chest has been closed; and
              • Only TEE done for specific diagnostic purposes may be separately payable during intraoperative use (TEE used for monitoring purposes is not separately payable). The results of the test must be used in making management decisions on the patient's intraoperative treatment. A covered service must include a complete interpretation/report by the performing physician, and must be available if requested.
              • 3-Dimensional Echocardiography
                New techniques for the 3-dimensional echocardiography are actively being developed. Initial reports were often related to mitral valve dysfunction (stenosis and prolapse) and measurement of left ventricular volumes. More recent studies have demonstrated its utility in creating multiplane images of the atrial and mitral valve structures. When billed with TEE (93312, 93314, 93315, 93317), it is indicated for:
                • The pre-operative planning of valve repair for multiple etiologies of mitral regurgitation;
                • In the assessment of mitral stenosis and in the accurate calculation of mitral valve area;
                • Pre-operative planning for diagnosis and treatment of atrial septal defects; and
                • Pre-operative and intraoperative planning for interventional cardiac procedures (e.g., transcatheter placement of occluders for atrial septal defects or patent foramen ovales, or paravalvular dehiscence or leaks;
                • Intraoperative mapping for atrial ablation procedures.
                • Three-dimensional echocardiography provides improved calculation of volumetric studies when compared to 2D echocardiography. However, its value in affecting clinical outcomes is not yet proven and is therefore not considered medically necessary.
                  
                  TEE is indicated for cardioversion in patients:
                • Requiring urgent (not emergent) cardioversion for whom extended pre-cardioversion anticoagulation is not desirable;
                • Who have had prior cardioembolic events thought to be related to intra-atrial thrombus;
                • For whom anticoagulation is contraindicated and for whom a decision about cardioversion will be influenced by TEE results; and
                • For whom intra-atrial thrombus has been demonstrated in previous TEE. (ACC/AHA/ASE 2003 Guideline Update, pgs. 49-50)
                  
                  Limitations:
                  
                  Screening examinations to identify structural cardiac abnormalities in the absence of established diagnoses, signs or symptoms, are not considered reasonable and necessary.
                  
                  TEE does not provide incremental information over that obtained by TTE in the serial assessment and management of pericardial pathology. Therefore, it will not be covered, unless there are loculated posterior effusions or adequate visualization of the pericardium is not possible by TTE.
                  
                  In general, TTE provides accurate and serial noninvasive assessment of global and regional left ventricular function. Unless TTE is technically inadequate and clinical data is insufficient for a management decision, TEE will not be covered. Transthoracic echocardiographic assessment of left ventricular function is considered preferable to TEE in all other circumstances.
                  
                  Intraoperative TEE (93318) is reimbursable to a cardiologist or other physician who is not part of the surgical/anesthesia team but only when performed as a diagnostic test and not for monitoring purposes (TEE for intraoperative monitoring is included in the anesthesia care).
                  
                  In aortic root dilation in Marfan Syndrome or other connective tissue syndromes, the ACC AHA/ASE 2003 Guideline Update recommends TTE over TEE as the first choice for examination. "TEE should only be used if the examination is incomplete or additional information is needed." (pg. 42.)
                  
                  In most patients with valvular prostheses TTE provides diagnostic functional information and noninvasive serial follow-up. However, in some patients, acoustical shadowing can decrease data acquisition. If TTE provides adequate information for diagnosis and management, then TEE is not covered. The medical record should document any need for additional information.
                  
                  In general, TTE can reliably diagnose or exclude evidence of potentially embolic material located in a ventricle. The TEE may complement TTE, particularly to assess for left atrial thrombus and patent foramen ovale or atrial septal aneurysm. The additional information that can be provided by TEE should be reasonably anticipated to be of therapeutic relevance before the patient is subjected to TEE, otherwise the TEE is not covered.
                  
                  Training Requirements:
                  
                  Substandard studies often lead to preventable repetition of studies and overutilization of services. Medicare expects a satisfactory level of competence from providers who submit claims for services rendered for these services to be considered medically necessary. Tests performed by providers not meeting these levels of competence will be denied.
                  
                  The acceptable levels of competence are outlined as follows:
                  a. For the technical portion, an acceptable level of competence is fulfilled when the image acquisition is obtained under any one of the following conditions:
                  • The service is performed by a physician; or
                  • The technical portion of the service is performed by a technician who is credentialed as either a Registered Diagnostic Cardiac Sonographer (RDCS) through the American Registry of Diagnostic Medical Sonographers or as a Registered Cardiac Sonographer (RCS) through the Cardiovascular Credentialing International; or
                  • Any non-physician personnel used by an IDTF to perform tests must demonstrate the basic qualifications to perform the tests in question and have training and proficiency as evidenced by licensure or certification by the appropriate State health or education department. In the absence of a State licensing board, the technician must be certified by an appropriate national credentialing body. The IDTF must maintain documentation available for review that these requirements are met. (42 CFR, Section 410.33c)
                  • b. For the professional portion, an acceptable level of competence is fulfilled when the interpretation is performed by a physician meeting any one of the following requirements:
                    • The physician is board certified in Cardiovascular Diseases or Perioperative Transesophageal Echocardiography (National Board of Echocardiography); or
                    • The physician has Level II training in transesophageal echocardiography (including documentation of the performance of 25 esophageal intubations and 50 supervised interpretations), as defined by the American College of Cardiology/American Heart Association/ American College of Physicians Task Force on Clinical Competence in Echocardiography, or the equivalent of Level II training as set forth in that document, or
                    • The physician has been credentialed for this procedure by the hospital where the physician performs this service.
                      
                      CGS providers submitting claims for these services will be allowed a 2-year grace period (until 07/01/2011) to meet these standards.
                      
                      Other Comments:
                      
                      For claims submitted to the Part A MAC: This coverage determination also applies within states outside the primary geographic jurisdiction with facilities that have nominated CGS Administrators, LLC to process their claims.
                      
                      Bill type codes only apply to providers who bill these services to the Part A MAC. Bill type codes do not apply to physicians, other professionals and suppliers who bill these services to the carrier or Part B MAC.
                      
                      Limitation of liability and refund requirements apply when denials are likely, whether based on medical necessity or other coverage reasons. The provider/supplier must notify the beneficiary in writing, prior to rendering the service, if the provider/supplier is aware that the test, item or procedure may not be covered by Medicare. The limitation of liability and refund requirements do not apply when the test, item or procedure is statutorily excluded, has no Medicare benefit category or is rendered for screening purposes.
                      
                      For outpatient settings other than CORFs, references to "physicians" throughout this policy include non-physicians, such as nurse practitioners, clinical nurse specialists and physician assistants. Such non-physician practitioners, with certain exceptions, may certify, order and establish the plan of care as authorized by State law. (See Sections 1861[s][2] and 1862[a][14] of Title XVIII of the Social Security Act; 42 CFR, Sections 410.74, 410.75, 410.76 and 419.22; 58 FR 18543, April 7, 2000.)
                      
                      For dates of service prior to April 1, 2010, FQHC services should be reported with bill type 73X. For dates of service on or after April 1, 2010, bill type 77X should be used to report FQHC services.

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A covered service must include a complete interpretation/report by the performing physician, and must be available if requested.

The patient's medical record must contain documentation that fully supports the medical necessity for services included within this LCD. (See "Indications and Limitations of Coverage.") This documentation includes, but is not limited to, relevant medical history, physical examination, and results of pertinent diagnostic tests or procedures, as well as reasons for repeat testing.

In those instances in which repeat tests were denied, the physician must document a good faith effort was made to identify them and to request copies of them from previous providers, in order for CGS to consider reimbursement for such tests on appeal.

Each service requires a formal written report with interpretation. This report should be kept on file with copies of image documentation (paper or tape) for review if requested. All appropriate measurements should be included in the report.

A Doppler interrogation should state the modes used and should give both qualitative and quantitative information.

Documentation of the qualifications of personnel performing tests, as described in the Indications section of the LCD, should be available on request.

All documentation must be submitted upon request.

• TEE services will be covered twice per year for all conditions except endocarditis (ICD-10 code I39, M32.11), for which four (4) services per year will be covered.
• TEE may be repeated in patients with repeat episodes of atrial fibrillation/flutter prior to cardioversion.
• Services exceeding this parameter will be considered not medically necessary, unless there is documentation that the tests were performed for clinical indications reflecting a change in the patient’s status or underlying cardiac condition, or documentation of a new unrelated condition, sign or symptom.
• In those instances in which repeat tests were denied and a physician has documented a good faith effort to identify them and to request copies of them from previous providers, then CGS could reimburse such tests on appeal.
• These guidelines do not apply to tests performed on hospital inpatients.

This bibliography presents those sources that were obtained during the development of this policy. CGS Administrators, LLC is not responsible for the continuing viability of Web site addresses listed below.

ACC/AHA Task Force Report, ACC/AHA Guidelines for the Clinical Application of Echocardiography, JACC. 1990;16(7):1505-28.

AdminaStar Federal and other Medicare contractors' policies.

AHA Medical/Scientific Statement (Feinberg WM, chair) Guidelines for the management of transient ischemic attacks. From the ad hoc committee on guidelines for the management of transient ischemic attacks of the stroke council of the American Heart Association. Stroke. 1994;25:1320-1335.

Ansari A, Transesophageal two-dimensional echocardiography: current perspectives. Prog Cardiovasc Dis. 1993;35(5):349-397.

Besson G, Bogousslavsky J, Hommel M, et al. Patent foramen ovale in young stroke patients with mitral valve prolapse. Acta Neurol Scand. 1994;89:23-26.

Biner S, Rafique AM, Kar S, et al. Live three-dimensional transesophageal echocardiography-guided transcatheter closure of a mitral paraprosthetic leak by amplatzer occluder. JASE. 2008;21(11):1282.e7-1282.e9. (published online 15 August 2008).

Blanchard, D, Kimura BJ, Dittrich HC, DeMaria AN. Transesophageal echocardiography of the aorta. JAMA. 1994;272(7):546-551.

Braunwald E. ed. Heart Disease, A Textbook of Cardiovascular Medicine. 4th ed. WB Saunders, Philadelphia, PA 1992.

Carrier Medical Directors' Cardiology Clinical Workgroup

Cerebral Embolism Task Force. Cardiogenic brain embolism. Arch Neurol. 1986;43:71-84.

Cheitlin MD, Alpert JS, Armstrong WF, et al. ACC/AHA Guidelines for the clinical application of echocardiography: executive summary. a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Clinical Application of Echocardiography). J Am Coll Cardiol. 1997;29:862-79.

Cheitlin MD, Armstrong WF, Aurigemma GP, et al. ACC/AHA/ASE 2003 guideline update for the clinical application of echocardiography: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASE Committee to Update the 1997 Guidelines for the Clinical Application of Echocardiography). 2003. Available at: http://www.acc.org/clinical/guidelines/echo/index.pdf. Accessed: March 14, 2006.Updated URL: http://www.acc.org/qualityandscience/clinical/guidelines/echo/index.pdf. Accessed: October 27, 2006.

Cigarroa JE, Isselbacher EM, DeSanctis RW, Eagle KA. Diagnostic imaging in the evaluation of suspected aortic dissection. Old standards and new directions. N Engl J Med. 1993;328(1):35-43.

Daniel WG, Mhgge A. Transesophageal echocardiography. N Engl J Med. 1995;332(19):1268-1279.

Daniel WG. Transcatheter closure of patent foramen ovale. Therapeutic overkill or elegant management for selected patients at risk? Circulation. 1992;86(6):2013-2015 (editorial.)

deBelder MA, Lovat LB, Tourikis L, Leech G, Camm AJ. Limitations of tranosesophageal echocardiography in patients with focal cerebral ischaemic events. Br Heart J. 1992;67:297-303.

deBelder MA, Tourikis L, Leech G, Camm J. Risk of patent foramen ovale for thromboembolic events in all age groups. Am J Cardiol. 1992;69:1316-1320.

Demopoulos LA, Tunick PA, Bernstein NE, et al. Protruding atheromas of the aortic arch in symptomatic patients with carotid artery disease. Am Heart J. 1995;129:40-44.

DeRook FA, Comess KA, Albers GW, Popp RL. Transesophageal echocardiography in the evaluation of stroke. Ann Intern Med. 1992;117:922-932.

Dhandheria B. Transesophageal echocardiography; concise review for primary-care physicians. Mayo Clinic Proc. 1994;69:856-863.

Hanna JP, Sun JP, Furlan AJ, et al. Patent foramen ovale and brain infarct. Echocardiographic predictors, recurrence, and prevention. Stroke. 1994;25:782-786.

Homma S, DiTullio MR, Sacco RL, et al. Characteristics of patent foramen ovale associated with cryptogenic stroke. A biplane transesophageal echocardiographic study. Stroke. 1994;25:582-586.

Hung J, Lang R, Flachskampf F, et al. 3D echocardiography: a review of the current status and future directions. J. Am. Soc Echocardiography. 2007;20:213-233.

Isselbacher KJ, Braunwa E, Wilson JD, Martin JB, Fauci AS, Kasper DL. Eds. Harrison's Principles of Internal Medicine. 13th ed. McGraw Hill, New York 1994.

Jones EF, Calafiore P, Donnan GA, Tonkin AM. Evidence that patent foramen ovale is not a risk factor for cerebral ischemia in the elderly. Am J Cardiol. 1994;74:596-599.

Khoury AF, Afridi I, QuiZones MA, Zoghbi WA. Transesophageal echocardiography in critically ill patients: feasibility, safety, and impact on management. Am Heart J. 1994;127:1363-1371.

Kronzon I, Sugeng L, Perk G, et al. Real-time 3D-transesophageal echocardiography in the evaluation of post-operative mitral annuloplasty ring and prosthetic valve dehiscence. Submitted for publication October 2008.

Kronzon I, Tunick PA. Transesophageal echocardiography as a tool in the evaluation of patients with embolic disorders. Prog Cardiovasc Dis. 1993;36(1):39-60.

Lindower PD, Gutterman DD. Detection of cardioembolic sources with echocardiography. Comprehensive Therapy 1994. 20(3):174-180.

Louie EK, Konstadt SN, Rao TLK, Scanlon PJ. Transesophageal echocardiographic diagnosis of right to left shunting across the foramen ovale in adults without prior stroke. J Am Coll Cardiol. 1993;21:1231-1237.

Lucas C, Goullard L, Marchau Jr M, et al. Higher prevalence of atrial septal aneurysms in patient with ischemic stroke of unknown cause. Acta Neurol Scand. 1994;89:210-213.

Mhgge A, Daniel WG, Haverich A, Lichtlen PR. Diagnosis of noninfective cardiac mass lesions by two-dimensional echocardiography. Comparison of the transthoracic and transesophageal approaches. Circulation. 1991;83:70-78.

Mitusch R, Stierle U, Tepe C, et al. Systemic embolism in aortic arch atheromatosis. Dur Heart J. 1994;15:1373-1380.

Otto, Catherine M. Textbook of clinical echocardiography. 2nd ed., W.B. Saunders Co., 2000.

Pearlman AS. Detecting prosthetic valve dysfunction. ACCEL. 1995; 27(10):tape B, side 3 (interview with Holmes, Jr DR.)

Pearson AC, Nagelhout D, Castello R, et al. Atrial septal aneurysm and stroke: a transesophageal echocardiographic study. J Am Coll Cardiol. 1991;18:1223-1229.

Pepi M, Tamborini G, Maltagliati A, et al, Head-to-head comparison of two-and three-dimensional transthoracic and transesophageal echocardiography in the localization of mitral valve prolapse, J Am Coll Cardiol. 2006;48:2524-2530.

Perk G, Lang RM, Garcia-Fernandez MA, et al. Transcatheter interventions use of real time three dimensional transesophageal echocardiography in intracardiac catheter based interventions. Journal of the American Society of Echocardiography. 2009;22(8).

Petty GW, Orencia AJ, Khandheria BK, Whisnant JP. A Population-based study of stroke in the setting of mitral valve prolapse; risk factors and infarct subtype classification. Mayo Clin Proc. 1994;69:632-634.

Sansoy V, Abbott RD, Jayaweera AR, Kaul S. Low yield of transthoracic echocardiography for cardiac source of embolism. Am J Cardiol. 1995;75:166-169.

Stratton JR, Lighty, Jr GW, Pearlman AS, Ritchie JL. Detection of left ventricular thrombus by two-dimensional echocardiography: sensitivity, specificity, and causes of uncertainty. Circulation. 1982; 66:156-166.

Sugeng L, Shernan SK, Salgo IS, et al. Live 3-dimensional transesophageal echocardiography initial experience using the fully-sampled matrix array probe. J Amer Coll Cardiol. 2008;52(6):446-9.

Sugeng L, Shernan SK, Weinert L, et al. Real-time 3D transesophageal echocardiography in valve disease: comparison with surgical findings and Evaluation of prosthetic valves. J Am Soc Echocardiography. 2008;21:1347–1354.

Wiet SP, Pearce WH, McCarthy WJ, et al. Utility of transesophageal echocardiography in the diagnosis of disease of the thoracic aorta. J Vasc Surg. 1994;20:613-620.

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