Comprehensive Transoesophageal Echocardiography Examination

Transcription

1 IJUTPC PICTORIAL REVIEW Comprehensive Transoesophageal Echocardiography Examination Comprehensive Transoesophageal Echocardiography Examination 1 Ravi Hebballi, 2 Ann Ngui 1 Consultant in Cardiothoracic Anaesthesia and Critical Care Medicine, Glenfield Hospital University Hospitals of Leicester, United Kingdom 2 Clinical Fellow in Cardiothoracic Anaesthesia and Critical Care Medicine, Glenfield Hospital University Hospitals of Leicester, United Kingdom Correspondence: Ravi Hebballi, Consultant in Cardiothoracic Anaesthesia and Critical Care Medicine, Glenfield Hospital University Hospitals of Leicester, LE3 9QP, Leicester, United Kingdom, Phone: , Fax: ravi.hebballi@uhl-tr.nhs.uk ABSTRACT Transoesophageal echocardiography (TEE) use has become an integral part in the care of cardiac surgical patients. This is evolving to be used in other subspecialties. The purpose of this article is to introduce the novice echocardiographer to a stepwise approach in image orientation and acquisition. Keywords: Transoesophageal echocardiography, Comprehensive examination. INTRODUCTION Transoesophageal echocardiography (TEE) has the unique advantage of portability and the ability to obtain high-resolution images of the normal and abnormal cardiovascular anatomy, function and is relatively easy to perform with a low risk of complications. GENERAL PRINCIPLES Indications Indications for TEE are expanding rapidly. The Society of Cardiovascular Anaesthesiologists (SCA) has recently updated the guidelines on the use of TEE (Table 1). 1 Contraindications There are many contraindications for performing TEE examination (Table 2). In some, TEE can be used with caution if the expected benefit outweighs the potential risk provided the appropriate precautions are used. Assessment Informed consent should be obtained during assessment which should include questions regarding dental status, swallowing difficulties, presence of hiatus hernia and previous gastric or oesophageal surgery. Probe Placement The procedure should only be performed by adequately trained individuals to minimise risks and complications. TEE examination should be performed in a fasting patient, who is either anaesthetised or sedated. Prior to insertion, probe should be examined for any existing damage. The wheels of the probe should be unlocked and in neutral position (described below) to avoid trauma. If the patient is anaesthetised, the lubricated TEE probe is inserted gently by performing a jaw lift. The rigid laryngoscope-assisted insertion of the TEE probe may reduce the incidence of oropharyngeal mucosal injury, odynophagia, and the number of insertion attempts. 2 Probe Manipulation Once in the oesophagus, the transducer should be gently guided and the operator should never apply undue force. There are 4 probe manipulations for optimal image acquisition. The probe manipulations described here (Fig. 1) are made with reference to the operator standing at the patient s head and looking towards the patient s feet. 1. Advance, withdraw: Pushing or pulling the tip of the TEE probe. 2. Turn to right, turn to left (also referred to as clockwise and anticlockwise): Rotating the anterior aspect of the TEE probe to the right or left of the patient. 3. Anteflex, retroflex: Anteflex is flexing the tip of the TEE probe anteriorly by turning the large control wheel clockwise (Fig. 2). Retroflex is flexing the tip of the TEE probe posteriorly by turning the large wheel anticlockwise. 4. Flex to right, flex to left: Flexing the tip of the TEE probe with the small control wheel to the patient s right or left. The probe flexion to the right and left may not be necessary and should be avoided to minimise trauma to the oesophagus. International Journal of Ultrasound and Applied Technologies in Perioperative Care, May-August 2010;1(2):

2 Ravi Hebballi, Ann Ngui The Sector Display The ultrasound signals originate perpendicularly from the tip of the TEE probe located in either the oesophagus or stomach. The apex of the image sector formed on the display shows structures close to the oesophagus (For example, left atrium in the midoesophageal views and inferior wall of the left ventricle in transgastric views) and the arc of the image sector shows more distal structures (For example, apical parts of left ventricle in midoesophagial views and anterior wall of the left ventricle in transgastric views). Fig. 1: Probe manipulation Table 1: Indications for TEE examination 1 Cardiac and thoracic aortic procedures Cardiac and thoracic aortic surgery For adult patients without contraindications, TEE should be used in all open heart (e.g. valvular procedures) and thoracic aortic surgical procedures and should be considered in coronary artery bypass graft surgeries as well To confirm and refine the preoperative diagnosis To detect new or unsuspected pathology To adjust the surgical plan accordingly To assess results of surgical intervention In small children, the use of TEE should be considered on a case-by-case basis because of risks unique to these patients (e.g., bronchial obstruction). Catheter-based intracardiac procedures For patients undergoing transcatheter intracardiac procedures, TEE may be used. Noncardiac surgery TEE may be used when the nature of the planned surgery or the patient s known or suspected cardiovascular pathology might result in severe haemodynamic, pulmonary, or neurologic compromise. If equipment and expertise are available, TEE should be used when unexplained life-threatening circulatory instability persists despite corrective therapy. Critical care For critical care patients, TEE should be used when the diagnostic information that is expected to alter management cannot be obtained by transthoracic echocardiography or other modalities in a timely manner. Table 2: Contraindications for TEE examination Absolute Relative Perforated viscus Zenker s diverticulum Oesophageal stricture Barrett s oesophagus Active gastrointestinal haemorrhage Oesophageal deformity Oesophageal tumours Previous oesophageal surgery Oesophageal diverticulum Postradiation therapy of oesophageal area Oesophageal scleroderma Coagulopathy Recent upper gastrointestinal surgery Oesophageal varices Vascular ring Tracheo-oesophageal fistula 90 JAYPEE

3 IJUTPC Comprehensive Transoesophageal Echocardiography Examination Multiplane Angle and Image Orientation The TEE probe has the ability to rotate the image around the axis of the centreline of the sector to view the complex threedimensional structure of interest in its entirety (Fig. 3). This is possible because the multiplane probes allow imaging plane from 0 degree through to 180 degrees with the use of an electronic switch (Fig. 2), while the transducer tip remains in a fixed position. At a multiplane angle of 0 degree, the patient s rightsided structures will be displayed on the left of the image display (Fig. 4a). By rotating the multiplane angle forward to 90 degrees left side of the image display shows posterior structures (Fig. 4b). Further rotating the multiplane angle to 180 degrees shows the patient s left side structures to left of the display. This is the mirror image of 0 degree (Fig. 4c). Long axis means the view along longitudinal length of the structure being examined. Conversely short axis means the view along the transverse section of the structure. Once the structure of interest is in the view, it should be centred within the image plane. Echocardiography machine setting and adjustments are important for optimal image quality. RECOMMENDED VIEWS The American Society of Echocardiographers/Society of Cardiovascular Anaesthesiologists have recommended a series Fig. 2: The TEE probe controls include the big wheel for ante and retroflexion, small wheel for right and left flexion, multiplane angle electronic switch Fig. 3: Multiplane angle and image orientation (a) Multiplane angle 0 (b) Multiplane angle 90 (c) Multiplane angle 180 Fig. 4: Multiplane angle and image orientation International Journal of Ultrasound and Applied Technologies in Perioperative Care, May-August 2010;1(2):

4 Ravi Hebballi, Ann Ngui of 20 Standard Views for TEE (Table 3). 3 These views are usually obtained at four TEE tip positions in the oesophagus and stomach. 1. Upper oesophageal (20-25 cm from incisors) 2. Mid oesophageal (30-40 cm from incisors) 3. Transgastric (40-45 cm from incisors) 4. Deep transgastric (45-50 cm from incisors). It may be easier to obtain the midoesophageal four chamber (ME4C) view of the heart first and make it as a reference point to obtain all other views. In this view, the machine controls are adjusted for optimal image resolution. In order to obtain 20 recommended standard TEE views, probe manipulation starts at the ME4C view together with the required multiplane angle changes. The illustrated views are semi-schematic representations presented in their ideal shape with anatomic correlations. Many of these views are also used for colour Doppler, pulse wave Doppler and continuous wave Doppler examinations. There are also other various non-standard views used for evaluation of a specific structure. ABBREVIATIONS ME4C midoesophageal 4 chamber, PA pulmonary artery, PV pulmonic valve, LV left ventricle, LA left atrium, RV right ventricle, RA right atrium, MV mitral valve, TV tricuspid valve, IAS interatrial septum, LAA left atrial appendage, CS coronary sinus, AV aortic valve, LVOT left ventricular outflow tract, RVOT right ventricular outflow tract, SVC superior vena cava, IVC inferior vena cava, RPA right pulmonary artery ME4C midoesophageal 4 chamber. Risks and Complications The safety of ultrasound usage is well established. Risks and complications are infrequent but can be fatal if care is not exercised. The foremost risk is misinterpreting the results leading to potentially harmful interventions. Other risks include odynophagia (0.1%), dental trauma (0.1%), upper gastrointestinal haemorrhage (< 0.1%), oesophageal perforation (< 0.1%), bleeding, aspiration, and dislodgement of endotrachael tube. There is also a theoretical risk of transmission of infection if probe is not properly cleaned. Limitations TEE will be of limited value if the views are inadequate for diagnosis. Imaging can become difficult in patients with hiatus hernia or the stomach being full of air. CONCLUSION The operator should work methodically to obtain all possible views in some sequence. However, not all 20 views are possible in all the patients. Although all attempts should be made to undertake a complete exam, the operator can concentrate on the area of interest initially when time is limited. Table 3. The recommended views (adapted from Shanewise JS et al) Standard view Illustrated view TEE view Upper oesophageal views (20-25 cm from incisors) 1. Aortic arch long axis (0 ): From ME4C view probe is pulled out by about 10 cm. Key structures seen: Aortic arch, left brachiocephalic vein. 2. Aortic arch short axis (90 ): The angle is increased to 90. Key structures seen: Aortic arch, PA, PV, left brachiocephalic vein. 92 JAYPEE

5 IJUTPC Comprehensive Transoesophageal Echocardiography Examination Midoesophageal views (30-40 cm from incisors) 3. Four-chamber (0-20 ): Insert the probe to about 30 to 40 cm from the incisor teeth and adjust the machine controls for optimal image resolution. Key structures seen: LV, LA, RV, RA, MV, TV, IAS, septal and lateral ventricular walls (basal, mid, apical). 4. Mitral commissural (60-70 ): Then increase the angle to 60 to 70. Key structures seen: MV, LV, LA. 5. Two-chamber ( ): Then increase the angle to 80 to 100. Key structures seen: LV (Inferior and anterior walls), LA, LAA, MV, CS. 6. Long axis ( ): Then increase the angle to 120 to 160. Key structures seen: LV (posterior and anteroseptal walls), LA, AV, LVOT, MV, ascending aorta. International Journal of Ultrasound and Applied Technologies in Perioperative Care, May-August 2010;1(2):

6 Ravi Hebballi, Ann Ngui 7. RV inflow-outflow (60-90 ): From ME4C view probe is pulled out by 1 to 2 cm and increase the angle to 60 to 90. Key structures seen: RV, RA, TV, RVOT, PV, PA, inferior free right ventricular wall. 8. AV short axis (30-60 ): From ME4C withdraw the probe by 1 to 2 cm and at 30 to 60, 3 AV leaflets ( Benz sign ) are seen. Key structures seen: AV, IAS, coronary ostia, LVOT, PV. 9. AV long axis ( ): From ME4C view withdraw the probe by 1 to 2 cm and at 120 to 160, AV leaflets are seen. Key structures seen: AV, LVOT, proximal ascending aorta, right PA. 10. Bi-caval ( ): From ME4C view withdraw the probe, turn to right and at 80 to 110 IAS can be seen. Key structures seen: RA, SVC, IVC, IAS, LA. 11. Ascending aortic short axis (0-60 ): From ME4C view probe is pulled out by 2 to 5 cm. Key structures seen: Ascending aorta, SVC, PA, right PA. 94 JAYPEE

7 IJUTPC Comprehensive Transoesophageal Echocardiography Examination 12. Ascending aortic long axis ( ): Then the angle is increased to 100 to 150. Key structures seen: Ascending aorta, right PA. 13. Descending aorta short axis (0 ): From ME4C turn the probe to the left and decrease the depth. Key structures seen: Descending thoracic aorta, left pleural space. 14. Descending aorta long axis ( ): Then the angle is increased to 90. Key structures seen: Descending thoracic aorta, left pleural space. Transgastric views (40-45 cm from incisors) 15. Basal short axis (0-20 ): From ME4C view, advance the probe into the stomach until the MV is seen. Key structures seen: LV, MV, RV, TV. 16. Mid short axis (0-20 ): Advance the probe further to view two papillary muscles. Key structures seen: LV, RV, papillary muscles. International Journal of Ultrasound and Applied Technologies in Perioperative Care, May-August 2010;1(2):

8 Ravi Hebballi, Ann Ngui 17. Two-chamber ( ): Increase the angle 80 to 100. Key structures seen: LV, MV, chordae, papillary muscles, CS, LA. 18. Long axis ( ): Increase the angle 100 to 120. Key structures seen: LVOT, AV, MV. 19. RV inflow ( ): From mid transgastric view rotate the probe to right to get RV and then increase the angle 100 to 120. Key structures seen: RV, TV, RA, TV chordae, papillary muscles. Deep transgastric view (45-50 cm from incisors) 20. Long axis (0-20 anteflexion): From ME4C advance the probe carefully into the stomach until the heart is not seen, then with anteflexion probe is withdrawn gently. Key structures seen: LVOT, AV, ascending aorta, arch. The increasing popularity and availability of TEE have made it an attractive modality for imaging. Real time 3D imaging and miniature TEE transducer probes will revolutionise this modality of imaging. REFERENCES 1. Practice guidelines for perioperative transesophageal echocardiography. An Updated Report by the American society of anaesthesiologists and the society of cardiovascular anaesthesiologists task force on transesophageal echocardiography. Anaesthesiology. May 2010;112(5): SungWon Na, Chang Seok, et al. Rigid Laryngoscope-assisted insertion of transesophageal echocardiography probe reduces oropharyngeal mucosal injury in anesthetized patients. Anaesthesiology 2009;110: Shanewise JS, Cheung AT, Aronson S, et al. ASE/SCA guidelines for performing a comprehensive intraoperative multiplane transoesophageal echocardiographic examination: Recommendations of the American society of echocardiography council for intraoperative echocardiography and the society of cardiovascular anesthesiologists task force for certification in perioperative transesophageal echocardiography. Anaesthesia and analgesia 1999;89: JAYPEE