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A Standard Transoesophageal Echocardiogram

Protocol written by the Education Committee of the British Society of Echocardiography: Richard Wheeler (Lead Author), Richard Steeds (Chair), Bushra Rana, Gill Wharton, Nicola Smith, Jane Allen, John Chambers, Richard Jones, Guy Lloyd

Download Minimum Dataset for a Transoesophageal Echocardiography (2010)

Introduction

A pdf of the guidelines can be found here

1. Introduction

• This document aims to provide a framework for performing an adult transoesophageal echo (TOE) in a variety of clinical settings e.g. cardiology outpatients, cardiac theatre, intensive care. The layout is not only a minimum dataset but also proposes a recommended sequence in how to perform a comprehensive study. This is supported by text which gives a brief description of important issues at each view.

• This will hopefully promote a systematic approach to TOE which is critical for education and training but also for reviewing studies performed by different operators or between different hospital sites.

• It is recognised that not all views may be possible in all patients and in particular there are certain views that are sometimes poorly tolerated e.g. deep transgatric, upper oesophageal. The decision to omit a view must therefore be made by the operator taking into account the balance between the risks of inadequate data versus patient safety and comfort.

2. Patient safety

• Transoesophageal echo is semi-invasive with the potential for serious complications, albeit rare. It is therefore mandatory to have a routine checklist for certain conditions and problems which may either contraindicate the study or be a cause for concern e.g. oesophageal stricture, previous gastrooesphageal surgery, loose teeth/dentures. This checklist should be documented, preferably in a specific transoesphageal document/careplan within the medical notes.

• Conscious sedation is used in many units as a routine to facilitate TOE. Only individuals trained in the use of such techniques should administer sedative drugs. Continuous monitoring of oxygen saturations during and after the procedure is mandatory with full resuscitation equipment being readily available.

• Echo labs should have written protocols for the decontamination of probes and sterility of the procedure room. These protocols should be agreed with local trust infection control departments.

3. Identifying Information

• Patient name

• A second unique identifier such as hospital number or date of birth

• Identification of the operator e.g. initials

4. An ECG should be attached ensuring good tracings to facilitate the acquisition of complete digital loops.

5. Intraoperative TOE

• Intraoperative TOE is now a well established procedure that may involve cardiologists, cardiothoracic anaesthetists or cardiac physiologists. It is strongly recommended that such studies follow precisely the same format as a TOE performed in different settings e.g. a diagnostic study in cardiology outpatients. This approach has a sound medico legal justification and minimises the risk of missing important diagnoses that may not be apparent on the preoperative transthoracic echo. With this in mind, this document has been prepared with the direct involvement of the Association of Cardiothoracic Anaesthetists and its representatives Justiaan Swanevelder, David Duthie and Donna Greenhalgh.

• To that end, intraoperative TOE needs to be well coordinated in order to allow time for a complete study. It is desirable to obtain most of the data before the chest/pericardium is open as this may affect the images e.g. dimensions of the tricuspid annulus.

• The clinician must be aware that the physiology of the patient may be significantly different during intraoperative TOE due to the effects of general anaesthesia, fluid status or vasoactive drugs. This is an important principle in deciding whether the TOE data should be obtained before the patient is listed for surgery. The most widely quoted example is in the assessment of the severity of mitral regurgitation which may vary widely dependent on the physiology at the time of the study.

6. Duration

• It is recommended that 45-60 minutes is allowed for each TOE, which includes preparation of the patient e.g. cannulation, consent etc, and may include a preparatory TTE. It is recognised that certain clinical circumstances may necessitate a more focused approach to the image acquisition but this is a clinical judgement.

7. Reporting

• All studies should be completed by the issue of a formal report, documented in the medical notes. Ideally this should be in the form of a standardised computerised report available on all contemporary echo systems. The TOE images should be stored in a format that is reliable and easy to access for review, with the current recommendation for digital storage and regular server back-up.

8. Measurements

• This document indicates several measurements which can be made during a routine TOE. However, it is expected that the vast majority of patients will have already had transthoracic echocardiography (TTE). There is a more extensive evidence base for TTE measurements which should therefore be used where possible.

• Some TOE measurements are difficult to perform due to proximity of the transducer e.g. LA dimensions. Some measurements may be prone to error if off axis images have been obtained e.g. LV dimensions.

• However, certain measurements e.g annular dimensions or aortic root size, are usually more precise on TOE.

List of abbreviations:

AS/AR Aortic stenosis/Aortic regurgitation

ASD Atrial septal defect

CFM Colour flow mapping

CS Coronary sinus

CW Continuous wave doppler

DET Deceleration time

FS Fractional shortening

IAS Interatrial septum

IS, antS, lat, inf, post Inferior septum, anterior septum, inferior, posterior LV walls

LUPV, LLPV, RUPV, RLPV Left upper, left lower, right upper, right lower pulmonary veins

LVDd/s Left ventricular diameter in diastole and systole

LVSd/s Left ventricular septal width in diastole and systole

LA/RA LV/RV Left/right atrium Left/right ventricle

MS/MR Mitral stenosis/Mitral regurgitation

PA Pulmonary artery

PFO Patent foramen ovale

PHT Pressure half time

PISA Proximal isovelocity surface area

PW Pulse wave doppler

RVd Right ventricular cavity diameter in diastole

RVSP Right ventricular systolic pressure

TOE Transoesophageal echo

TR Tricuspid regurgitation

TTE Transthoracic echo

VSD Ventricular septal

* Assessment of LV and MV views - All of these views should be reassessed with colour flow Doppler over the mitral valve. PW and CW should be used in either the 4 chamber or long axis views.

* Assessment of the aortic valve - These views should be repeated with colour flow Doppler. Alignment is not possible for spectral Doppler. The four chamber mid oesophageal view can also be used with slight flexion or withdrawal of the probe in order to assess the ventricular aspect of the AV and also to image aortic regurgitation.

* Assessment of the interatrial septum - All of these views should be repeated with colour flow Doppler to look for ASD/PFO. Reducing the Nyquist limit may help to visualise low velocity flow across the septum. Always remember to reset the Nyquist limit for the rest of the study.

* Assessment of the right heart - Tricuspid annular dimensions in the 4 chamber view provide useful data for the cardiac surgeon in the setting of tricuspid repair. There is a paucity of data regarding normal ranges indexed for body surface area.

All of these views should be repeated with colour flow Doppler to assess the tricuspid and pulmonary valves. PW/CW can be used to assess flow through the pulmonary valve in the mid oesophageal view at 0°

TOE Dataset LV & MV

Diagram 1 - Standard imaging planes of the mitral valve from the mid oesophageal window

MV mid oeso window

This diagram helps to understand the different sections of the MV that are visualized in the standard mid oesophageal imaging planes.

The four chamber view at 0º is an oblique cut through the MV and will visualize different parts of the valve according to the depth of probe insertion, the degree of flexion/extension and also the anatomical lie of the heart which may vary between patients. This means that A3/A2/A1 extending to P2/P1 may be in view at any one time. It is not usually possible to image A3/P3 at 0º.

The diagram also illustrates the correct anatomical planes for annular dimensions - the bicommissural view (major axis) and the long axis view (minor axis) [2]. These measurements in end diastole and end systole provide useful data for the cardiac surgeon in the setting of mitral repair. There is a paucity of data for normal ranges indexed for body surface area.

VIEW	MODALITY	MEASUREMENTS	EXPLANATORY NOTE	IMAGE
Assessment of the LV Mid oesophageal 4 chamber 0-20	2D		Inferoseptum and lateral walls. May require extension of probe to bring apex in to view. Focus can be moved towards the apex to improve quality of image. Careful assessment for apical thrombus/masses.	Click to enlarge
Assessment of the LV Mid oesophageal 2 chamber 80-100°	2D	LVDd/s	Inferior and anterior walls. Measurements can be made with 2D calipers for LV dimensions at the junction of the basal and middle thirds of the LV.[1]	Click to enlarge
Assessment of the LV Mid oesophageal long axis 120-150°	2D		Assessment of LV function - inferolateral and anteroseptal walls.	Click to enlarge
			*All of these views should be reassessed with colour flow Doppler over the mitral valve. PW and CW should be used in either the 4 chamber or long axis views.*
Assessment of the Mitral Valve Mid oesophageal 4 chamber 0-20°	2D		Several sections of the MV can be imaged in this view - (see diagram 1 for full explanation). Particular attention to the mitral annulus, leaflet morphology, leaflet motion and the subvalvar apparatus.	Click to enlarge
Assessment of the Mitral Valve Mid oesophageal 4 chamber 0-20°	2D		A1/P1. Flexion or withdrawal of the probe slightly will bring A1/P1 into view. The anterolateral commissure can be assessed.	Click to enlarge
Assessment of the Mitral Valve Mid oesophageal bicommisural view 60-70°	2D	Commissure to commissure annulus dimension (end diastole and end systole)	The imaging plane now brings both commissures into view. This is an appropriate anatomical plane to measure the annular dimension - diagram 1. ##IMAGE##	Click to enlarge
Assessment of the Mitral Valve Mid oesophageal Posteromedial commisure 90°	2D		A3/P3. The posteromedial commissure can be seen by turning the probe towards the aorta and then coming back to the MV.	Click to enlarge
Assessment of the Mitral Valve Mid oesophageal long axis 120-150°	2D	Anterior to posterior annulus dimension (end diastole and end systole).	A2/P2. This is the second anatomical plane which allows the mitral annulus to be measured - diagram 1.	Click to enlarge
Assessment of the Aortic Valve Mid oesophageal Short axis 40-60°	2D		Flexion/extension or insertion and withdrawal of the probe will allow imaging above and below the valve making sure to image at the leaflet tips to assess opening. The coronary ostia can be seen above the valve.
Assessment of the Aortic Valve Mid oesophageal Long axis 120-150°	2D	LVOT/aortic annulus	The NCC is seen in the near field with the RCC in the farfield. Movement of the probe from left to right is essential in this view to image the extremities of the valve.
Assessment of the Aortic Valve Mid oesophageal Long axis 120-150°	2D	LVOT/aortic annulus	The LVOT dimension is measured in midsystole from the septal endocardium to the anterior mitral valve leaflet approximately 0.5-1cm from the valve orifice.[5] The aortic 'annulus' is measured from the hinge points of the AV in mid-systole.
			These views should be repeated with colour flow Doppler. Alignment is not possible for spectral Doppler. The four chamber mid oesophageal view can also be used with slight flexion or withdrawal of the probe in order to assess the ventricular aspect of the AV and also to image aortic regurgitation.
Assessment of the LA/LAA Mid oesophageal 4 chamber 0-20°	2D	LA dimension in two planes	The probe needs to be moved from left to right to image all parts of the LA completely. The LA area/volume can be difficult to obtain from TOE due to the proximity to the transducer. Dimensions in two planes can be measured in this view (semiquantitative).
Assessment of the LA/LAA Mid oesophageal 2 chamber 90°	2D		As above, movement of the probe from left to right will maximise the chance of imaging all corners of the LA.
Assessment of the LA/LAA Mid oesophageal 4 chamber 0-20°	2D		The LAA can be imaged often helped by flexion or withdrawal of the probe slightly. Careful attention should be made to distinguish pectinate muscles from thrombus. The depth and focus can be adjusted to maximise the quality.
Assessment of the LA/LAA Mid oesophageal LAA view 60-130°	2D		It is essential to image the LAA in at least 2 planes. One or more lobes can be seen when the multiplane is turned beyond 90°. Movement of the probe to the left can keep the LAA in view. Look out for spontaneous echo contrast.
Assessment of the LA/LAA Mid oesophageal LAA view 0-130°	Colour Doppler		Colour Doppler can help assess the extent of the LAA cavity.
Assessment of the LA/LAA Mid oesophageal LAA view 0-130°	PW	Emptying velocities	PW Doppler can be placed within the mouth of the LAA (not more than 1cm) in order to quantify emptying velocities.
Assessment of the interatrial septum Mid oesophageal IAS 0-20°	2D		The interatrial septum is well seen on TOE due to its close proximity to the transducer. Lipomatous hypertrophy is frequently seen in this view.
Assessment of the interatrial septum Mid oesophageal IAS 40-80°	2D		The presence of a patent foramen ovale can be assessed in this view. Note the insertion of the Eustachian valve near the inferior vena cava in the right atrium.
Mid oesophageal bicaval 80-120°	2D		It is essential to image the IAS in multiple views to exclude ASD/PFO. Sinus venosus defects can be easily missed by incomplete imaging of the IAS near the insertion of the IVC and SVC.
			All of these views should be repeated with colour flow Doppler to look for ASD/PFO. Reducing the Nyquist limit may help to visualise low velocity flow across the septum. Always remember to reset the Nyquist limit for the rest of the study.
Assessment of the Pulmonary Veins Mid oesophageal 4 chamber 0-20°	Colour Doppler		The upper pulmonary veins tend to insert more vertically into the LA. Flexion or withdrawal of the probe can bring into view. Note the close relationship of the LUPV to the LAA.
Assessment of the Pulmonary Veins Mid oesophageal 4 chamber 0-20°	Colour Doppler		The lower pulmonary veins tend to insert more horizontally into the LA. Inserting the probe further and turning further to the left can help image the LLPV.
Assessment of the Pulmonary Veins Mid oesophageal 4 chamber 0-20°	Colour Doppler		After turning the probe to the right, flexion or withdrawal of the probe can help image the RUPV.
Assessment of the Pulmonary Veins Mid oesophageal modified bicaval view 90-110º	Colour Doppler		The RUPV can often be easier to image by starting with the bicaval view to visualize the SVC and then turning the probe further to the right whilst keeping the colour doppler in position.
Assessment of the Pulmonary Veins Mid oesophageal 4 chamber 0-20°	Colour Doppler		Inserting the probe further and turning the probe to the right can bring in the RLPV.
Assessment of the Pulmonary Veins Mid oesophageal 4 chamber 0-20°	PW		The PW cursor is placed 1cm into the mouth of any pulmonary vein but usually the LUPV is the best aligned. Two pulmonary veins should be analysed in each patient.
Assessment of the Right Heart Mid oesophageal 4 chamber 0-20°	2D		The right ventricle can be assessed in more detail for regional and global function. The septal leaflet is on the right with the anterior or posterior leaflet on the left depending on how far the probe is inserted.[3]
Assessment of the Right Heart Mid oesophageal 4 chamber 0-20°	2D		RV size can be assessed at the base and the mid point in end diastole [1] The tricuspid annulus can be measured at end systole and end systole from hinge point to hinge point.
Assessment of the Right Heart Mid oesophageal RV inflow/outflow 60-80°	2D		Regional and global RV function can be further assessed. The posterior leaflet is on the left with the anterior leaflet to the right. The pulmonary valve can also be seen in this view.
			Tricuspid annular dimensions in the 4 chamber view provide useful data for the cardiac surgeon in the setting of tricuspid repair. There is a paucity of data regarding normal ranges indexed for body surface area.
Assessment of the Right Heart Mid oesophageal modified RV inflow 110-130º	2D		The tricuspid valve can also be imaged at this multiplane angle aided by turning the probe to the right.
Assessment of the Right Heart Mid oesophageal modified RV inflow 110-130º	Colour Doppler		This view often allows TR to be assessed using CW Doppler due to the vertical alignment.
Assessment of the Right Heart Mid oesophageal modified RV inflow 110-130º	CW	TRmax	Doppler estimate of RVSP may be performed.

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