Transesophageal Echocardiography: A Sonographer's Perspective

Transesophageal Echocardiography: A Sonographer's Perspective Janel M. Mays, RN, RDCS, Barbara A. Nichols, RN, RDCS, Renee C. Rubish, RN, RDCS, Kristin W. O'Meara, RN, and Patricia A. Koverman, RN, RDCS, Rochester, Minnesota

Clinical transesophageal echocardiography is increasingly being applied for the evaluation of numerous functional and anatomic cardiac abnormalities. This new technology has opened an area of invasive ultrasonography that has changed and expanded the role of the cardiac sonographer. The sonographer is essential for the implementation and performance of this recent advance in echocardiography. (J AM Soc ECHOCARDIOGR 1991;4:513-8.)

Transesophageal echocardiography (TEE) has been

described as "a new window to the heart."l Although the physician performs and interprets the results of TEE, the cardiac sonographer plays an essential part in the implementation and performance of this most recent advance in echocardiography. The sonographer must be familiar with all aspects of TEE to understand the indications, prepare the patient for the procedure, and assist the physician during the imaging portion of the examination. The sonographer's role encompasses activities before, during, and after the examination. The purpose of this article is to assist sonographers in understanding their essential contribution to the TEE examination. TRAINING OF SONOGRAPHERS

TEE is a semiinvasive examination with a low but real incidence of potentially serious complications. 2 Because of this possibility, emergency equipment must be available and medical and paramedical staff should be appropriately trained in basic life support. In our laboratory a registered nurse sonographer coordinates and assists during the transesophageal procedure. 3 Because of the semi invasive nature of TEE, the skills of a registered nurse are preferred for monitoring the patient closely, obtaining vital signs, administering medications, inserting intravenous lines, From the Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic and Mayo Foundation. Reprint requests: Janel M. Mays, RN, Mayo Clinic, 200 First St. S.W., Rochester, MN 55905 . 27 / 1/29985

and using suction, oxygen, or other emergency equipment. A properly trained non-nurse sonographer may perform all of these functions except the administration of medications. Trained support staff are essential to best meet the needs of the patient and assist with the ultrasound examination. BACKGROUND OF TEE

Cardiac ultrasonography was first introduced by Edler and Hertz4 in 1954. Since then, advances in machine and transducer design have resulted in unique applications of cardiac ultrasonography. Personnel in a comprehensive cardiac ultrasound laboratory can now perform many of the functions available in an invasive cardiac catheterization laboratory. With echocardiography, high-quality images can be obtained, cardiac function assessed, hemodynamics measured, and blood flow patterns visualized. These abilities have led to the evolving concept of an echocardiography laboratory becoming an "imaging and hemodynamic" laboratory. 5 Despite the improvements in equipment, successful cardiac imaging still requires that the heart lie within the field of view of the ultrasound transducer. 6 This principle led to the development of the esophageal transducer. The TEE transducer lies adjacent to the posterior surface of the heart and is separated from the heart by a distance of only a few millimeters. 3,6 Because TEE places the transducer close to the heart, it overcomes many of the limitations of a precordial examination and truly provides a new window to the heart. Two-dimensional TEE was first introduced in the 513

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early 1980s. 7·14 Most of the early work was performed within the operating room, but an outpatient procedure was gradually developed. Unique indications for this procedure include diagnosis of aortic dissection; complications of myocardial infarction and adult congenital heart disease; assessment of prosthetic and native valve disease; and visualization of the left atrial appendage, cardiac tumors, and valvular vegetations. 3 TRANSESOPHAGEAL SCOPE

TEE permits real-time visualization of the heart by using a 5 MHz phased-array imaging transducer mounted on the distal tip of a 100 em endoscope, devoid of suction and optics. 3.ls Most transesophageal transducers are capable of two-dimensional M-mode, pulsed-wave Doppler, and color flow imaging. Newer TEE transducers incorporate biplane imaging l6 and continuous-wave Doppler imaging. Ultrasound systems must be specifically adapted to incorporate TEE transducer capability. Because TEE has known complications, including death, the transesophageal scope should be used only by a properly trained physician familiar with echocardiography, esophageal intubation, and transesophageal tomographic anatomy.3.IS The cardiac sonographer plays an importaFlt role in maintaining the integrity of the transesophageal scope. Before each use the TEE transducer must be visually and manually inspected for defects in the insulating covering (such as metallic protrusions, holes, dents, abrasions, or cracks). This inspection should be performed with the tip of the scope in each flexion position. If defects are suspected, the scope should not be used until an additional safety inspection has been performed. Damage to the scope may cause trauma or expose the patient to infective, caustic, or, rarely, electrical complications. Electrical safety checks should be performed regularly by a technically qualified person to ensure that the outer insulating layer of the TEE probe is intact. 3,15 Damage to the TEE scope may be prevented or markedly reduced by regular use of a bite block. Involuntary biting of the TEE scope during the examination may cause irreparable damage. In addition to prolonging the life of a scope, the use of a bite block protects a patient's teeth from damage during the procedure. If the patient wears dentures or oral prostheses, these should be removed before the examination is started. 15

Storing the TEE transducer properly is essential to prevent damage and to increase the life of the scope. The carrying case for the TEE scope should always be used when the instrument is transported from one location to another, unless the instrument has not been cleaned and disinfected (the foam padding that lines the case cannot be disinfected if it is contaminated by an unclean scope). After a bedside examination the scope should be placed in a plastic bag and carefully carried to the echocardiography laboratory to be cleaned properly. For long-term storage the TEE scope should not be kept in its carrying case. A vertical wall rack with a clear protective cylinder is the best mechanism for interim storage. The wall rack should be mounted away from extremes in temperature or direct sunlight. While the TEE scope is stored the transducer tip should be maintained in a straight rather than flexed position. 15 PREPARATION FOR PROCEDURE

An organized environment and a comfortable examination table promote patient confidence and relaxation. The TEE sonographer helps prepare the room and supplies for the examination (Table 1). Monitoring equipment, medications, suction apparatus, oxygen, blood pressure cuff, and other supplies should be ready before the patient arrives. An emergency cart with life support equipment should be available. Preparation of the patient ideally begins well in advance of beginning the procedure. The patient's physician can help prepare the patient for the procedure, which is similar to upper endoscopy. The patient must be informed to take nothing orally for 4 to 6 hours before TEE. If systemic sedation is to be used, the patient should be informed not to drive or be exposed to potentially injurious situations for at least 12 hours after the examination. In this situation someone should accompany the patient after the examination. Routine endocarditis prophylaxis is not recommended, except for patients with prosthetic valves. 3 Currently prophylaxis is given just before the examination according to the recommendations of the American Heart Association for patients at high risk. 17 When the patient arrives for the TEE, the sonographer must ensure that the patient has been properly informed about the procedure, including explanations about preparations for the examination, what

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Table 1

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A summary of the sonographer's role in TEE

Before procedure Preparation of equipment and supplies Assemble supplies Medications, normal saline flushes, and contrast medium (such as indocyanine green dye) Intravenous supplies (angiocatheter, three-way stopcock) Lidocaine spray and tongue blade Scope lubricant: lubricating jelly or viscous lidocaine Gloves, safety glasses, TEE probe, and bite block Maintain and check suction, oxygen, and basic life support equipment Cover patient's pillow with absorbent material Patient preparation Confirm that patient has had no oral intake for 4 to 6 hours before TEE Obtain brief history of drug allergies and current medications Explain procedure to patient Obtain baseline vital signs and monitor electrocardiogram Remove patient's denrures, oral prostheses, and eyeglasses Establish intravenous line for administration of medications Place patient in the left lateral decubitus position with wedge support and safety restraints Assist patient during esophageal intubation, such as head position, breathing, and reassurance Drugs Endocarditis prophylaxis: American Heart Association recommendations Pharyngeal anesthesia: lidocaine 10% spray Drying agent: glycopyrrolate (Robinul) Sedative (anxiolytic): midazolam hydrochloride (Versed) During procedure Reinforce physician's instructions Position and maintain bite block Monitor vital signs: electrocardiogram, respiratory rate and pattern, blood pressure, and oxygen saturation Comfort and reassure the patient Use oral suction if necessary Have basic life support equipment available After procedure Assist patient during recovery period; observe for 30 minutes if systemic sedation was used Monitor vital signs and respiratory status Remove intravenous line Complete and reinforce instructions with patient and family Instruct patient not to drive for 12 hours if sedation was used Record vital signs and patient's condition on dismissal Arrange for escort if patient is not completely recovered Clean scope with enzymatic solution and glutaraldehyde disinfectant

the patient can expect during the test, and precautions after its completion. Time should be allowed for the patient to ask questions. Most physicians will explain the procedure before starting the examination. The sonographer or nurse confirms that the patient has been fasting for at least 4 hours and that postprocedural arrangements have been made if systemic sedation is to be used. A brief history of drug allergies, current medications, significant dysphagia, or esophageal disease should be obtained by the sonographer or physician. If a drying agent (anticholinergic) or sedative is to be used, the sonographer confirms that the patient has no significant history of

asthma, glaucoma, or prostatism. Baseline vital signs are obtained. The patient's dentures, other oral prostheses, and eyeglasses are removed. The registered nurse or physician will establish an intravenous route to administer medications, inject contrast agent, and provide a route in the event of an emergency. Mter the physician has applied the topical anesthetic to the patient's throat, the sonographer assists in positioning the patient in the left lateral decubitus position facing the examiner. The patient's right leg is usually placed in front of the left leg to ensure proper positioning and limit the patient's tendency to roll to the right. A wedge is placed behind the

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patient's back for comfort and is secured with a restraint strap. The sonographer is stationed at the patient's head during the procedure. The physician and sonographer should wear disposable gloves during the procedure. When TEE is performed on a patient with an infectious disease, goggles and a mask should be worn also. Systemic medications, if used, are given by a registered nurse or physician. MEDICATIONS

Patients who have outpatient TEE receive various medications, including (1) a topical anesthetic to diminish gagging and laryngospasm, (2) a drying agent to reduce oral secretions, and (3) a sedative (anxiolytic) to reduce fear and anxiety and provide transient amnesia of the event. 3 Topical anesthetic. Topical anesthesia of the oropharynx is accomplished with a topical anesthetic solution (lidocaine). Peak effect occurs in 2 to 5 minutes and lasts for 30 to 45 minutes. Side effects include impaired swallowing and numbness of the tongue and oral mucosa. As a consequence, the patient should avoid hot liquids and solids for 30 to 60 minutes after the procedure or until the effects have passed. 3 (The current drug of choice is lidocaine 10% spray.) Drying agent. Many examiners use an an.ticholinergic agent to decrease salivary secretions and to reduce the need for oral suction. This medication is given intravenously approximately 5 minutes before the TEE procedure. Potential side effects include a mild increase in heart rate and an exacerbation of symptoms in patients with glaucoma, asthma, or prostatism. 3 (The current drug of choice is glycopyrrolate. The usual adult dose is 0.2 mg bolus administered intravenously.) Sedative (anxiolytic). These medications are given to decrease anxiety. They are given slowly intravenously to produce mild visible sedation in 3 to 5 minutes. New agents cause a transient amnesia of the event in approximately 80% of patients. The patient should be observed for about 30 minutes after the procedure. Side effects include fluctuations in vital signs (decreased respiratory rate, hypotension, and tachycardia), confusion, dizziness, visual disturbance, and retrograde amnesia. Reaction time under stress (operating an automobile or machinery) may be prolonged, and the patient should be cautioned against performing potentially injurious tasks for

about 12 hours.3 (The current drug of choice is midazolam. The usual adult dose is 1 to 5 mg given slowly intravenously.) THE EXAMINATION

Esophageal intubation and instructions to the patient during the examination are the responsibility of the physician. 3 The sonographer assists the physician and observes and comforts the patient. Before examination begins the sonographer should put on protective gloves and place lubricant (a lubricating jelly or viscous lidocaine) on a 4 X 4 inch gauze pad for the physician to lubricate the scope. The sonographer assists the patient in flexing his or her head toward the chest to allow better entry into the oral pharynx. During insertion of the scope the sonographer stabilizes the patient'S head and reinforces the physician's instructions. Mter the scope is inserted the sonographer continuously monitors the patient's reactions and ensures that ventilation and vital signs are stable. The sonographer should maintain the patient's head in a comfortable flexed position and encourage the patient to lie calmly and breathe naturally through the nose or mouth. Throughout the procedure the sonographer comforts and reassures the patient. The proper position of the bite block must also be maintained to avoid damage to the scope's protective covering. 15 The sonographer should note the depth of scope insertion when requested by the physician and must be prepared to use oral suctioning if necessary. 3 AFTER THE EXAMINATION

Immediately after the examination the sonographer assists in clearing the patient's secretions and monitors the patient's vital signs. The intravenous line is removed after the patient is stable. When the patient is fully aware of the surroundings, side effects and precautions are discussed with the patient and family. If the patient is hospitalized, the nursing staff should be aware of side effects and precautions related to TEE. The recovery time varies from 15 to 45 minutes, depending on the medications used and the patient's tolerance of the procedure. If the patient appears unsteady at dismissal, arrangements for transport by wheelchair should be made. Vital signs, the medications received, instructions given to the

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patient, and the condition of the patient at dismissal should be documented on the patient's record. CLEANING THE TRANSDUCER AND

BITE BLOCK

The transducer and bite block must be properly cleaned and disinfected after each examination. Only the flexible shaft of the transesophageal scope should be immersed during cleaning. The proximal head and controls should be wiped with a gauze pad moistened with a disinfectant. The first step in cleaning is to wash the scope and bite-block in an enzymatic soap (such as Endozime [Ruhof Corp., Valley Stream, New York] or Protozyme) which assists in removing adherent secretions. Mter it is washed the scope should be rinsed with tap water and dried before being placed in disinfectant. The enzymatic solution is discarded after each use. 3 The second step is to soak the scope and bite-block in a glutaraldehyde disinfectant solution (such as Metricide or Cidex) for 20 minutes, which destroys potential bacterial and viral contaminants. Care must be used when preparing, handling, and discarding these caustic solutions. Protective gloves and safety glasses should always be worn. After the scope is removed from the disinfectant, it should be rinsed thoroughly in tap water. It is important to take time to examine the entire shaft for cracks, protrusions, or abrasions. The scope is then dried and placed in the storage rack. The scope should be air dried for about 20 minutes to allow any residual adherent glutaraldehyde to evaporate. The used glutaraldehyde solution should be changed every 2 weeks or according to package directions. 3,15 SPECIAL CONSIDERATIONS

Special considerations need to be taken when performing TEE in young, elderly, or critically ill patients. Patients younger than 10 years usually cannot undergo endoscopy in the outpatient environment because they usually require general sedation. Most currently available TEE transducers are most suitable for adults. The elderly patient is sensitive to systemic sedation and requires attentive monitoring. Head positioning

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and the patient's cooperation are essential. Because of a redundant hypopharynx and cervical spurs in the posterior pharynx, intubation may be difficult and risky. Critically ill patients require an individual approach to care. TEE can be easily performed in intubated patients. Patients who have an endotracheal tube can undergo TEE in any position because aspiration is not a problem. Nasogastric tubes or other esophageal devices usually do not have to be withdrawn before the TEE scope is inserted. 3 CONCLUSION

Currently TEE is increasingly applied for the evaluation of numerous functional and anatomic cardiac abnormalities. This new technology has opened an area of invasive ultrasonography that has changed and expanded the role of the cardiac sonographer and provided new avenues of responsibility for the sonographer. We thank Drs. J. B. Seward and A. J. Tajik for their guidance and assistance in the preparation of this article; echocardiologists and sonographers associated with the Mayo Clinic's Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory; and Michelle R. Frank and Kristine L. Kesler for secretarial assistance.

REFERENCES 1. Erbel R, Khandheria BK, Brennecke R, Meyer J, Seward JB, Tajik AI. Transesophageal echocardiography: a new window to the heart. Berlin: Springer-Verlag, 1989:360. 2. Khandheria BK, Seward JB, Tajik AI. Transesophageal echocardiography. In: Braunwald E, ed. Heart disease: a textbook of cardiovascular medicine, 3rd ed. Philadelphia: WE Saunders, 1991:273-94. 3. Seward JB, Khandheria BK, Oh JK, et al. Transesophageal echocardiography: technique, anatomic correlations, implementation, and clinical applications. Mayo Clin Proc 1988;63:649-80. 4. Edler I, Hertz CH. Use of ultrasound refiectoscope for continuous recording of movement of heart walls. Kung Fysiogr Sallsk Lund Fordhandl 1954;24:40. 5. Seward JB. Cardiovascular ultrasound imaging and hemodynamic laboratory (echocardiography). Curr Opin Cardiol 1988;3:912-21. 6. De Bruijn NP, Clements FM, with a contribution by Hill R. Transesophageal echocardiography. 1st ed. Boston: Martinus Nijhoff Publishing, 1987: 133. 7. Frazin L, Talano JV, Stephanides L, Loeb HS, Kopel L, Gunnar RM. Esophageal echocardiography. Circulation 1976;54: 102-8.

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8. Matsumoto M, Oka Y, Strom I, et al. Application of transesophageal echocardiography to continuous intraoperative monitoring of left ventricular performance. Am J Cardiol 1980;46:95-105. 9. Matsuzaki M, Matsuda Y, Ikee Y, et al. Esophageal echocardiographic left ventricular anterolateral wall motion in normal subjects and patients with coronary artery disease. Circulation 1981;63: 1085-92. 10. Hisanaga K, Hisanaga A, Nagata K, Yoshida S. A new transesophageal real-time two-dimensional echocardiographic system using a flexible rube and its clinical application. Proceedings of the Japanese Sociery of Ultrasound in Medicine 1977;32:43-4. 11. Hisanaga K, Hisanaga A, Nagata K, Ichie Y. Transesophageal cross-sectional echocardiography. Am Heart J 1980; 100:605-9. 12. DiMagno EP, Buxton JL, Regan PT, et al. Ultrasonic endoscope. Lancet 1980; 1 :629-31. 13. Seward JB, Tajik AI, DeMagno EP. Esophageal phased-array sector echocardiography: an anatomic srudy. In: Hanrath P, Bleifeld W, Souquet I, eds. Cardiovascular diagnosis by ul-

14.

15. 16.

17.

trasound: transesophageal, computerized, contrast, Doppler echocardiography. The Hague/Boston: Martinus Nijhoff Publishing, 1982:270-9. Schiller NB. Evaluation of cardiac function during surgery by transesophageal 2-dimensional echocardiography. In: Hanrath P, Bleifeld W, Souquet I, eds. Cardiovascular diagnosis by ultrasound: transesophageal, computerized, contrast, Doppler echocardiography. The Hague/Boston: Martinus Nijhoff Publishing, 1982:289-93. Phased array ultrasound imaging transducer for transesophageal echocardiography user's guide. Andover, Massachuserts: Hewlert-Packard Co, 1987. Seward JB, Khandheria BK, Edwards WD, Oh JK, Freeman WK, Tajik AI. Biplanar transesophageal echocardiography: anatomic correlations, image orientation, and clinical applications. Mayo Clin Proc 1990;65:1193-213. A statement for health professionals by the Commirtee on Rheumatic Fever and Infective Endocarditis: prevention of bacterial endocarditis. Circulation 1984;70(suppl.): 1123A-7A.