TOE for anaesthetists

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Why this is examined / the one-line answer

Perioperative transoesophageal echocardiography (TOE/TEE) is the cardiac anaesthetist’s imaging language. On ANZCA Final and equivalent fellowship exams, candidates must name standard ASE/SCA views, describe a structured examination, know contraindications and complications, apply pre- and post-CPB checklists, and use TOE to diagnose weaning failure, air, SAM, dissection, and tamponade physiology. Governance frameworks (ANZCA PS46 family in Australia and New Zealand) frame training, supervision, reporting, and scope.

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One-line opener: I screen contraindications, perform a structured ME → TG → UE sweep using ASE/SCA nomenclature, answer specific pre- and post-CPB questions, and treat the image — while remembering that ACT gates and surgical haemostasis still rule the conduct of bypass. Hahn et al. ASE/SCA 2013 remains the core named reference for comprehensive examination structure.[2]

Governance, consent, and safety

ANZCA professional documents on perioperative echocardiography (PS46 family and related guidance) expect appropriate training, credentialing pathways, supervision for learners, image storage where available, and written or electronic reporting of findings that change management. Obtain consent or risk discussion when feasible (elective cardiac lists); in emergencies document necessity. Communicate new findings to the surgeon before irreversible steps (e.g. unexpected severe MR before planned CABG-only).

[2]

Contraindications (relative and absolute spectrum): oesophageal stricture, tracheoesophageal fistula, perforated viscus, active upper GI bleeding, severe dysphagia from obstructing lesions, recent oesophageal or gastric surgery, oesophageal diverticulum or tumour, and unstable cervical spine without mitigation. Relative concerns: varices (risk–benefit with hepatology/surgery), severe coagulopathy (still often performed in cardiac surgery with care), and previous radiation. Never force a probe against resistance.

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Complications: lip and dental trauma, oropharyngeal bleeding, odynophagia (common, usually self-limited), rare oesophageal tear or perforation, recurrent laryngeal nerve injury (rare), haemodynamic stimulation during insertion, endotracheal tube displacement, and distraction from the primary anaesthetic. Have a plan if bloody secretions or subcutaneous emphysema appear after insertion.

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ASE/SCA standard views (exam list)

Open the viva with a structured list, not a random walk around the heart. High-yield intraoperative vocabulary includes:

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Comprehensive examinations expand to the full ASE/SCA recommended set (Hahn et al.), including additional upper oesophageal, mid-oesophageal, and transgastric windows for pulmonary veins, right heart, and thoracic aorta segments as indicated.[2]

Basic versus comprehensive: a basic perioperative exam answers focused questions (ventricular filling and function, obvious catastrophic lesions, life-threatening causes of instability) and is the minimum crisis skill set. A comprehensive exam systematically evaluates all valves, chambers, great vessels within reach, and quantitative assessments when time and expertise allow — typically before CPB in valve surgery and whenever unexpected findings appear.

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Basic perioperative roles by phase

Pre-CPB

Confirm scheduled pathology and baseline severity (e.g. MR grade, AS gradients in context of anaesthesia loading conditions). Detect unexpected findings (PFO, additional valve disease, LVOT obstruction risk, aortic atheroma, ascending aortic pathology relevant to cannulation). Establish baseline ventricular function and regional wall motion. Screen for pericardial effusion. Plan cannulation and venting with the surgeon.

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During cannulation and CPB

Guide venous cannula position (ME bicaval for SVC/IVC wires and cannulae). Watch for aortic dissection flaps related to cannulation or cross-clamp. Assess LV distension and venting adequacy. Look for air during filling and de-airing. Confirm cardioplegia delivery indirectly via wall motion cessation when relevant.

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Weaning and early post-CPB

Preload and ventricular filling, RV and LV systolic function, regional wall motion suggesting graft or air problems, residual valve lesions after repair/replacement, dynamic LVOTO/SAM after mitral repair, residual air, and iatrogenic issues (new wall motion after vent site). After protamine, reassess for evolving haematoma or systolic anterior motion as loading changes.[3]

ICU return and delayed instability

Tamponade physiology (may be localised after cardiac surgery — chamber compression without classic global effusion), severe hypovolaemia, RV failure, regional ischaemia, and prosthetic valve dysfunction.

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Integration with CPB numbers and transfusion context

TOE does not replace anticoagulation gates: heparin 300–400 IU/kg to ACT ≥400–480 s before full bypass remains mandatory regardless of beautiful images. Flow and pressure targets still apply while imaging guides volume and vasoactive therapy. When bleeding is controlled, restrictive red-cell transfusion strategies as studied in TRICS III inform ICU haemoglobin targets — TOE helps decide whether instability is hypovolaemia, tamponade, or pump failure rather than defaulting to reflexive transfusion alone.[1][3]

Pre- and post-CPB checklist (say it as a list)

Pre-CPB checklist example:

1. Probe insertion safe; images adequate
2. Ventricular function and RWMA baseline
3. Valves relevant to operation graded
4. Aorta for cannulation/atheroma/dissection screen
5. Unexpected lesions communicated
6. Cannulae and wires confirmed as placed

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Post-CPB checklist example:

1. De-airing adequate
2. LV and RV function acceptable or supported
3. Valve repair/replacement competent (regurgitation, paravalvular leak)
4. No significant SAM/LVOTO
5. No new severe wall motion suggesting coronary issue
6. Loading conditions optimised before final surgical decisions
7. Findings documented and handed over

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Crisis algorithm with TOE

Hypotension off CPB or in ICU after cardiac surgery — image before endless pure pressor escalation when the probe is available:

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• Empty underfilled cavities → bleeding, vasoplegia with underfill, hypovolaemia → volume and surgical check
• RV dilation/failure → pulmonary hypertension, air, poor protection, embolism → support RV, reduce PVR, consider re-CPB
• LV systolic failure → inotropes, mechanical support pathway, technical coronary problem
• Tamponade-like constraint → surgical exploration even if effusion looks small
• Dynamic obstruction / SAM → volume, vasoconstriction, reduce inotropy, surgical revision if severe after mitral repair
• Severe residual valve lesion → revise repair/replace
• Coronary air → regional wall motion, Trendelenburg root strategies historically, support until air clears
• Dissection flap new → surgical emergency communication

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Treat the image, not only the number on the arterial line.[2]

Monitoring and equipment

TOE probe and machine checked before induction when planned. Bite guard. ECG gating. Colour and spectral Doppler capability. Recording system for archiving key loops. Alternative imaging (epicardial echo, TTE windows, pulmonary artery catheter) when TOE is contraindicated. Standard cardiac anaesthetic monitoring runs in parallel — TOE is additive.

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Intraoperative conduct tips examiners like

• Insert the probe after intubation when the airway is secure, unless a specific awake indication exists (rare in standard cardiac GA).
• Unlock the probe wheel when advancing; never force.
• Complete a systematic exam, then focus on the surgical question.
• Reassess after every major surgical change (grafts on, valve seated, clamp off).
• Loading conditions under anaesthesia alter gradients and regurgitation — interpret severity with that caveat.
• Close communication: “new severe MR, recommend inspection” beats silent anxiety.

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Postoperative / documentation plan

Written report of pre- and post-CPB findings, images archived when systems allow, handover to ICU including residual issues (mild MR, RV impairment, pacing dependence). Probe-related sore throat advice. Escalate odynophagia with fever or surgical emphysema as possible perforation.

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Special populations and comorbidities

Minimally invasive and robotic cardiac surgery: TOE is often essential because surgical exposure is limited. Structural heart / TAVI pathways: different imaging mixes (TTE, TOE, fluoroscopy) — know TOE’s role in complications. Non-cardiac surgery emergencies: basic TOE/TTE skills for unexplained shock when expertise exists. Oesophageal varices: multidisciplinary risk discussion. Paediatric TOE: size-appropriate probes and different lesion set. Hybrid theatres: coordinate with fluoroscopy and surgical access.

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SAQ answer scaffold

A 15-mark SAQ: After separation from CPB following mitral repair, BP is 70/40 mmHg despite noradrenaline.

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1. Immediate structure (3 marks): call out problem; confirm pacing/rhythm; look at TOE systematically.
2. Differential with views (5 marks): empty LV (TG SAX), RV failure, SAM (ME LAX), residual MR, tamponade physiology, air.
3. Management linked to image (4 marks): volume/vasoconstrict for SAM; inotropes for pump failure; surgical revision thresholds.
4. Governance (3 marks): document; communicate; note TOE limits and that ACT/protamine/surgical bleeding still matter.[2][3]

Viva stem bank and model phrases

Stem 1: “List your standard views.”
Model: “I work ME four-chamber, two-chamber, LAX, AV SAX/LAX, bicaval, then TG mid-SAX and related TG views, then upper oesophageal aortic arch views, expanding to the full ASE/SCA set as indicated.”

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Stem 2: “Contraindications?”
Model: “Oesophageal stricture, perforation risk lesions, severe obstructing dysphagia, recent oesophageal surgery — I will not force a probe; I choose alternative imaging and tell the team.”

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Stem 3: “Is TG mid-SAX enough?”
Model: “It is excellent for LV filling and RWMA but misses detailed valve anatomy — I do not call a comprehensive exam after one view.”

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Stem 4: “Role before aortic cannulation?”
Model: “I look for ascending aortic disease and unexpected dissection or heavy atheroma that changes cannulation strategy.”

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Stem 5: “PS46 in one sentence.”
Model: “It frames training, supervision, and governance so perioperative echo is a credentialed, reported medical act, not an informal hobby.”

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Common traps

• Calling a comprehensive exam after two views
• Missing RV while watching only LV
• Forcing probe placement against resistance
• Forgetting documentation and surgeon communication
• Interpreting valve severity without considering anaesthetic loading conditions
• Believing TOE replaces ACT, surgical inspection, or clinical bleeding assessment
• Ignoring localised tamponade after cardiac surgery because the effusion is not circumferential
• No alternative imaging plan when TOE is contraindicated

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View-by-view examination walkthrough (viva script)

Begin at mid-oesophageal depth. ME four-chamber assesses LV and RV size and function, mitral and tricuspid valves, and septal motion. Rotate and anteflex slightly for ME two-chamber (mitral leaflets, inferior and anterior walls). ME long-axis shows LVOT, aortic valve in long axis, mitral coaptation, and is the key screen for SAM after mitral repair. ME AV short-axis shows the three aortic cusps; ME AV long-axis adds aortic root dimensions and AR jets. Advance or withdraw carefully for ME bicaval to see SVC, IVC, interatrial septum, and venous cannulae. Advance into the stomach for TG mid short-axis — the workhorse for volume and regional wall motion (LAD, circumflex, and right coronary territories represented around the doughnut). TG two-chamber and basal views refine segments. Deep TG views align Doppler for aortic valve gradients when needed. Withdraw to upper oesophageal aortic arch long- and short-axis views for arch atheroma and dissection extension. This ME → TG → UE order is reproducible under stress.

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Quantitative concepts without false precision

Under anaesthesia, loading conditions change regurgitation severity and gradients. Report what you see with that caveat. Colour jet area alone misleads; use multiple parameters when expertise allows (vena contracta, pulmonary vein flow for MR, continuity equation concepts for AS with deep TG alignment). For LV function, end-systolic cavity obliteration suggests underfilling or hyperdynamic state; a dilated poorly thickening ventricle suggests systolic failure. RV failure shows dilation, flattening of the septum in patterns that suggest pressure or volume overload, and underfilling of the LV.

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Probe handling and machine setup that examiners notice

Check probe integrity and flexion before insertion. Use a bite block. Unlock wheels when advancing. Optimise depth, focus, gain, and colour scale for each structure rather than leaving factory settings. Store loops of key pre- and post-CPB findings. If images are poor (stomach air, hiatal hernia, probe position), say so and do not over-call pathology.

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Training pathway and limits of practice

Basic perioperative TOE for life-threatening diagnosis differs from comprehensive valvular quantification by an expert. Know your credentialing tier. When findings will change the operation (new severe MR before CABG, unexpected mass, ascending aortic aneurysm), escalate to the most experienced echocardiographer available and ensure the surgeon hears the finding before cannulation or definitive repair decisions. Limitations versus TTE include poor anterior cardiac views sometimes, incomplete aortic arch distal segments, and inability to image the abdominal aorta. PAC and advanced haemodynamic monitors complement but do not replace structural imaging.

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Pre-CPB decision examples linked to images

Unexpected severe MR before planned CABG: show the surgeon ME mitral views with colour; discuss repair or replacement plan change; do not let the case proceed as “grafts only” without explicit acknowledgement. Ascending aortic heavy mobile atheroma: change cannulation site or consider epiaortic scanning and different aortic handling. PFO with right-to-left risk in certain contexts: mention when relevant to air or shunt discussions. Severe AS underestimated: gradients under anaesthesia may fall with low stroke volume; integrate valve area concepts and surgical inspection. RV dysfunction before pericardiectomy or transplant pathways: sets inotropic and nitric oxide planning.

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Post-repair SAM specifically

After mitral repair, elongated anterior leaflet or reduced LV volume can produce systolic anterior motion with LVOTO and MR. ME LAX is the key view. Management ladder: restore volume, increase systemic vascular resistance (vasoconstrict), reduce pure inotropy/tachycardia, stop adrenaline-like drivers, deepen anaesthesia carefully; if refractory and severe, surgical revision (further repair or valve replacement). Saying “give volume and phenylephrine and look at ME LAX” is a high-yield model phrase.

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Air and de-airing

Air appears as bright bubbles on TOE. Right coronary ostium preference for air explains inferior wall motion issues after open left heart procedures. De-airing manoeuvres are surgical; anaesthesia contributes by positioning, ventilation strategies as requested, and confirming residual air before final weaning decisions. Massive air lock is a crisis: stop bypass mishaps, support, Trendelenburg root strategies historically, and TOE to track clearance.

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Documentation template

Indication; contraindication screen; probe tolerance; pre-CPB summary (ventricles, valves, aorta); intraoperative new findings; post-CPB summary (function, repair result, air, SAM absent/present); complications of probe; images archived; name of reviewing supervisor if trainee study. Handover to ICU should include residual issues that change management (pacing dependence, RV impairment, mild paravalvular leak being observed).

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Separation checklist spoken aloud

Before the surgeon asks to come off bypass, I confirm rhythm and rate are acceptable, residual air is minimal on TOE, biventricular function is supported or adequate, the valve or graft result is acceptable on the structured views, there is no critical SAM, filling is appropriate, and vasoactive infusions are primed. I state residual concerns explicitly. This spoken checklist prevents silent disagreement between anaesthesia, surgery, and perfusion at the most dangerous minute of the case. Record the same points clearly in the anaesthetic chart for the ICU handover team. [1]

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References

1. [1]Mazer CD, Whitlock RP, Fergusson DA, et al. Restrictive or Liberal Red-Cell Transfusion for Cardiac Surgery N Engl J Med, 2017.PMID 29130845
2. [2]Hahn RT, Abraham T, Adams MS, et al. Guidelines for performing a comprehensive transesophageal echocardiographic examination: recommendations from the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists J Am Soc Echocardiogr, 2013.PMID 23998692
3. [3]Levy JH, et al. What's fishy about protamine? Clinical use, adverse reactions, and potential alternatives J Thromb Haemost, 2023.PMID 37062523