Cardiovascular

Transesophageal echocardiography: Getting a clearer view

Transesophageal echocardiography (TEE) is a minimally invasive diagnostic study that can be done quickly and easily in most patients. Unlike transthoracic echocardiography (TTE), the more common echocardiographic study, TEE provides a clear view of virtually all cardiac structures unobstructed by bones, lungs, or the pericardial chest wall.

To perform TEE, the clinician places a probe into the esophagus. The esophagus is separated from the heart by only a thin sheet of muscle, with few structural barriers to transmission of imaging data. This results in much clearer images than with TTE. Also, the esophagus is posterior to the heart (the opposite vantage point of TTE), so TEE gives a clearer view of posterior cardiac structures. This perspective also gives the best view of the atria, atrial appendages, and thoracic aorta. In addition, TEE may provide the best view of tiny but clinically significant findings, such as valvular anomalies. (See Comparing transthoracic and transesophageal imaging by clicking the PDF icon above.)

Indications

Common indications for TEE include:

  • evaluation of suspected endocarditis
  • assessment of moderate to severe heart valve disease
  • investigation of acute aortic pathology
  • to find the potential source of an embolic stroke
  • to check for clots before elective cardioversion or ablation
  • when TTE results aren’t conclusive. (See TEE images before and after anticoagulation by clicking the PDF icon above.)

In intensive-care patients, TEE may be used to assess volume status or evaluate patients with unexplained hypotension or hypoxemia, as well as those with complications after myocardial infarction or blunt chest trauma. It’s also done in patients with conditions that can interfere with TTE, such as surgical drains, incisions or dressings, severe obesity, severe chronic obstructive pulmonary disease, emphysema, or mechanical ventilation.

Where TEE is performed

TEE can be done in any setting with the appropriate equipment, supplies, and staff. It may need to take place at the bedside for unstable special-needs patients or those having a simultaneous procedure. For portable TEE, common travel locations include emergency departments, operating rooms, intensive care units, and step-down areas.

In most cases, hemodynamically stable patients leave the inpatient unit to undergo the procedure. Some facilities have a dedicated TEE lab designed specifically for this test. A cardiac catheterization lab or a recovery area also may be used.


TEE is performed by cardiologists specially trained in echocardiography, assisted by specially trained and registered cardiac sonographers or registered diagnostic cardiac sonographers. Nursing staff caring for TEE patients must have training in conscious sedation, appropriate safety measures, and administration of contrast agents. (See Nursing research topics for TEE by clicking the PDf icon above.)

How TEE images guide patient management

TEE has many uses in evaluating various conditions and guiding their management.

Cardiovascular conditions

TEE can expedite safe elective cardioversion by ruling out a clot. For instance, patients with atrial fibrillation (AF) or atrial flutter (AFL) who aren’t receiving anticoagulants otherwise would have to wait 3 to 6 weeks before undergoing cardioversion to restore a normal heart rhythm. Studies show early return to a normal heart rhythm brings both immediate and extended benefits to these patients. TEE also is used to “clear” AF and AFL patients for imminent antiarrhythmic drug loading or interventional electrophysiology procedures, such as radiofrequency ablation.

  • Patent foramen ovale (PFO). Roughly one in four adults has a remnant opening between the atria, known as PFO, which potentially can cause cardio-pulmonary disorders. TEE can detect a PFO and determine whether it can be closed with a minimally invasive percutaneous device or requires open-heart surgery. For TEE, these patients are likely to receive an agitated contrast injection commonly called a bubble study. (See Echocardiography contrast agents by clicking the PDF icon above.)
  • Infective endocarditis (IE). Joint guidelines from the American Heart Association and the Infectious Diseases Society of America address TEE utility and cost effectiveness in diagnosing and managing IE. Patients with moderate to high clinical suspicion of IE (or with poor-quality TTE images) need to have a confirmed diagnosis, because IE requires prolonged antibiotic therapy. TEE also can determine the extent of valve destruction and the need for urgent surgery. At highest risk for IE complications are patients with prosthetic heart valves, a history of endocarditis, new murmur or heart failure, certain bacteremias, and new-onset heart block.
  • Mitral valve vegetation or endocarditis. Patients with cardiac valve disease may undergo TEE several times—before, during, and after surgery. This test helps to determine the effectiveness of medical management and establish the best timing for surgery. It also guides the choice between surgical repair and valve replacement and aids selection of an appropriate-size replacement valve. TEE can be used intraoperatively to assess functioning of the repaired or replacement valve.

Neurologic conditions

Neurologists may order TEE for patients with suspected thromboembolic events, such as stroke or transient ischemic attack—especially young patients and those who’ve had multiple or cryptogenic events.

Contraindications

In an emergency, no absolute contraindications to TEE exist. However, safety guidelines apply.

In patients with significant esoph­a­geal pathology or recent GI bleeding or surgery, TEE is contraindicated; the 17-mm, three-dimensional probe must be inserted blindly into the esophagus, which would put these patients at risk for esophageal perforation. Also, in patients who haven’t been on nothing-by-mouth status, TEE increases the aspiration risk in elective settings. Other risk factors for aspiration include age older than 70, conditions predisposing the patient to reflux (pain, opioid use, diabetes mellitus, ileus, and tobacco use), airway difficulties, and a high score on the American Society of Anesthesiologists’ physical status classification.

Relative contraindications include esophageal varices; patients should be evaluated for the risk of injury and bleeding caused by the TEE probe. Anemia of unknown etiology may signal occult GI bleeding and may be evaluated gastroenterologically before TEE. Dental problems can be significant; patients with loose teeth have an elevated risk for dental damage and aspiration. Other conditions that may interfere with TEE include cervical spine disease or spinal fusion, chest or neck radiation, and profound electrolyte abnormalities. Although hiatal hernia may interfere with imaging, it’s not a contraindication.

Patient preparation

Except in an emergency, proper preparation for TEE is required. Screen the patient for a history of drug allergies, problems related to conscious sedation, esophageal disease or surgery, or difficult eating and drinking. Evaluate the patient’s laboratory results, and be aware of his or her anticoagulation status. Assess bleeding risk as well; prothrombin, partial thromboplastin, and International Normalized Ratio must be below designated maximum values. Platelets and, in some facilities, hemoglobin must be above certain values. Alert the TEE team early if you identify any of these problems.

Make sure patients have been withholding oral intake (although in most cases, they can take medications with sips of water). Teach them about the procedure, reinforce their understanding, and address their concerns. Be aware that I.V. access is required for sedation and dentures must be removed for safety. Your facility may have a checklist for these items. (See Nursing responsibilities during and after TEE by clicking the PDF icon above.)

Complications

TEE complications include endotracheal-tube malposition (0.2% incidence), pain on swallowing (0.1%), upper GI bleeding (0.03%), dental injury (0.03%), and esophageal perforation (0.01%), Methemoglobinemia is a rare but potentially lethal acute hypoxic condition resulting from exposure to lidocaine and benzocaine. Staff should be aware of this complication to promote early recognition and treatment.

On the horizon

Real-time three-dimensional echo­cardiography is a newer technology used increasingly in echocardiography laboratories. Improvements in transducer technologies include development of a full matrix/array transducer, which acquires datasets that can be processed both online and offline. This allows display of cardiac structures, together with accurate measurements of left ventricular volumes and mass.

More recently, a miniaturized matrix probe has been coupled with a transesophageal probe. In some cases, this means TEE can help eliminate motion artifacts and improve accuracy of cardiac-chamber volume evaluation. The technique also yields a global perspective for visualizing cardiac valves and congenital anomalies.

Finally, a small, disposable TEE probe about the size of a nasogastric tube is now on the market. Used as an indwelling tube, it’s left in the esophagus for up to 72 hours, allowing clinicians to periodically assess hemodynamics in patients with complex cardiovascular conditions.

Selected references

American College of Cardiology Foundation Appropriate Use Criteria Task Force; American Society of Echocardiography; American Heart Association; American Society of Nuclear Cardiology; Heart Failure Society of America; Heart Rhythm Society; Society for Cardiovascular Angiography and Interventions; Society of Critical Care Medicine; Society of Cardiovascular Computed Tomography; Society for Cardiovascular Magnetic Resonance; American College of Chest Physicians, Douglas PS, Garcia MJ, Haines DE, et al. ACCF/ASE/AHA/ASNC/HFSA/HRS/SCAI/SCCM/SCCT/SCMR 2011 appropriate use criteria for echocardiography. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance American College of Chest Physicians. J Am Soc Echocardiogr. 2011;24(3):229-67.

Marchiondo K. Transesophageal imaging and interventions: nursing implications. Crit Care Nurse. 2007;27(2):25-8.

Mulvagh SL, Rakowki H, Vannan MA, et al.; American Society of Echocardiography. American Society of Echocardiography consensus statement on the clinical applications of ultrasonic contrast agents in echocardiography. J Am Soc Echocardiogr. 2008;21(11):1179-201.

Young KC, Benesch CG. Transesophageal echocardiography screening in subjects with a first cerebrovascular ischemic event. J Stroke Cerebrovas Dis.

Kathy Deavult Mullholand is a clinical nurse IV and a TEE nurse in the Pauley Heart Center, Virginia Commonwealth University Health System in Richmond, Virginia. Rachel M. Riley is the chief clinical officer at Kindred Hospital in Richmond, Virginia.

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