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← Section I · Physical Principles, Instrumentation, Examination Principles
I.B

Transesophageal Echocardiography, Intraoperative Echocardiography, and Catheter-Based Echocardiography (ICE)

24 cards

Notes

When to use TEE

  • Small structures (< 3 mm) that TTE cannot resolve.
  • LA appendage, interatrial septum, PFO/ASD detail, aortic dissection, prosthetic valves (esp. mitral), endocarditis vegetations.
  • TEE = CTA = MRA (sensitivity > 95%) for aortic dissection.
  • Confirmation of mitral annuloplasty dehiscence - 3D echo is the gold standard.

Preparation

  • NPO for 6 hours prior.
  • Conscious sedation: propofol or benzodiazepine.
  • Benzocaine spray → methemoglobinemia risk (Fe²⁺→Fe³⁺ oxidation; presents with cyanosis, low SaO₂, normal PaO₂). Treatment: IV methylene blue 1% (10 mg/mL).

Contraindications

  • Absolute: esophageal stricture, diverticulum, scleroderma, Mallory-Weiss tear, esophageal tumor or trauma; known perforation of stomach or esophagus; active GI bleeding; recent GI or oropharyngeal surgery.
  • Relative: esophageal varices (grade 1 OK, grade 4 no).

Insertion technique

  • Left lateral decubitus position, moderately sedated.
  • Probe with anterior flexion; inspect first, confirm image on screen before insertion.
  • Knobs should never be locked to avoid injury.
  • If the probe coils in the esophagus with tip toward the mouth → withdraw, retroflex, then advance.

Complications

  • Overall incidence 0.18–2.8 %. Highest (> 10 %) are hoarseness and lip injury. Mortality < 0.02 %.
  • Others: tooth damage, esophageal perforation (very rare).

Standard TEE views (28 required by ASE guidelines)

  • Upper esophageal: aortic arch views (30–35 cm from incisors).
  • Mid esophageal:
    • 4-Chamber: 0–20°
    • Commissural (3-2-1) TEE: 50–70°
    • 2-Chamber: 90°
    • Long-axis: 125–135°
  • Transgastric: always anteflex. Short-axis at mid-papillary is the primary intra-op view.
  • Deep transgastric: also anteflex; used for AV/LVOT gradients (best CW alignment).

Pulmonary vein imaging (TEE)

  • Right upper PV: near intra-atrial septum at 60° (or 0°).
  • Left upper PV: 110–140° (out of the standard 4Ch plane).

LA / LAA (TEE)

  • Emptying velocity < 20 cm/s in the LAA → high risk of severe SEC, thrombus, cardioembolism.
  • Spontaneous echo contrast - associated with prior CVA / peripheral embolism in AFib; marker for future embolic events.
  • LAA thrombi usually at the tip; may be multilobulated.
  • Pectinate muscles: finger-like ridges visible at 100–110°.
  • Post-surgical LAA ligation: high incidence of residual flow between LA and LAA.

Aorta imaging (TEE)

  • Blind spot: distal ascending aorta and proximal arch (obscured by air in trachea/main-stem bronchi).
  • Descending aortic dissection surrounded by fluid on TEE → pleural effusion, not pericardial.
  • Main PA and right PA visualized on TEE; left PA not well seen (bronchial air).
  • Arantius nodules: at center of the free margin of each of the three aortic cusps.

ICE (intracardiac echo)

  • Catheter-based, used during EP procedures (PVI, LAA closure) and structural interventions (PFO/ASD closure).
  • Guides trans-septal puncture - best A-P alignment via the aortic-root short-axis view. Needle manipulated posterior to the aorta.

Anatomic pearls

  • Thebesian valve = valve of the coronary sinus (RA opening).
  • Eustachian valve = valve of the IVC (RA).
  • Chiari network = fenestrated remnant of embryonic right valve of sinus venosus.
  • Coumadin ridge / warfarin ridge / "Q-tip" - muscular ridge between LAA and left upper PV; not thrombus.
  • Dilated coronary sinus - common causes: RA hypertension (TR, PH, RHF), CS fistula, anomalous PV drainage to CS, persistent left SVC to CS.

Cards

  • basicI.B-001
    How long should a patient be NPO before TEE?
    → 6 hours.
  • basicI.B-002
    List absolute contraindications to TEE.
    → Esophageal stricture, diverticulum, scleroderma, Mallory-Weiss tear, tumor, or trauma; known perforation of stomach or esophagus; active GI bleeding; recent GI/oropharyngeal surgery.
  • basicI.B-003
    Are esophageal varices an absolute contraindication to TEE?
    → No — relative. Grade 1 varices are acceptable; grade 4 are not.
  • basicI.B-004
    A patient becomes cyanotic after benzocaine spray during TEE — what is the diagnosis and treatment?
    → Methemoglobinemia (Fe²⁺ → Fe³⁺, low SaO₂ despite normal PaO₂). Treat with IV methylene blue 1% (10 mg/mL).
  • basicI.B-005
    What are the two most common TEE complications?
    → Hoarseness and lip injury (each > 10%). Overall complication rate 0.18–2.8%; mortality < 0.02%.
  • basicI.B-006
    Which TEE view angles best acquire mid-esophageal 4Ch, 2Ch, and LAX?
    → 4Ch: 0–20°. 2Ch: 90°. LAX: 125–135°. Commissural view: 50–70°.
  • basicI.B-007
    What is the TEE 'blind spot' of the aorta and why?
    → The distal ascending aorta and proximal arch — obscured by air in the trachea and main-stem bronchi that lie between the esophagus and this segment.
  • basicI.B-008
    What LAA emptying velocity threshold is associated with thrombus and cardioembolic risk?
    → < 20 cm/s. Associated with severe spontaneous echo contrast and subsequent embolic events.
  • basicI.B-009
    What is the sensitivity of TEE for aortic dissection?
    → > 95% — comparable to CT and MRA.
  • basicI.B-010
    Which imaging modality is the gold standard for confirming mitral annuloplasty ring dehiscence?
    → 3D echocardiography (usually 3D TEE).
  • basicI.B-011
    What position and probe orientation are used for TEE insertion?
    → Left lateral decubitus, moderate sedation, probe with anterior flexion. Inspect the probe and confirm a live image on screen before insertion.
  • basicI.B-012
    If a TEE probe coils in the esophagus with the tip toward the mouth, what maneuver corrects it?
    → Withdraw slightly, retroflex, then advance.
  • basicI.B-013
    During transgastric TEE imaging, what maneuver is universally applied?
    → Always anteflex (both standard and deep transgastric views).
  • basicI.B-014
    Where are LAA thrombi most commonly located?
    → At the tip of the appendage. They may be multilobulated. Pectinate muscles (visible around 100–110°) are the main mimic — should not be mistaken for thrombus.
  • basicI.B-015
    What is the Thebesian valve?
    → The valve of the coronary sinus at its opening into the right atrium.
  • basicI.B-016
    What is the 'Coumadin ridge' or 'Q-tip'?
    → A muscular ridge between the LAA orifice and the left upper pulmonary vein. Normal anatomy — not a thrombus.
  • basicI.B-017
    List four common causes of a dilated coronary sinus on echo.
    → 1) RA hypertension (severe TR, PH, RHF). 2) Coronary sinus fistula. 3) Anomalous pulmonary venous drainage to the CS. 4) Persistent left SVC draining to the CS.
  • basicI.B-018
    Which pulmonary artery is NOT well visualized by TEE and why?
    → The left pulmonary artery — obscured by air in the left main-stem bronchus. Main PA and right PA are seen well.
  • basicI.B-019
    During transseptal puncture, which TEE view provides the best A-P guidance?
    → Short-axis view at the level of the aortic root. The needle should be manipulated posterior to the aorta.
  • basicI.B-020
    State the standard TEE probe frequency for adult imaging.
    → 5–7 MHz — higher than TTE (2–5 MHz) because the target is closer to the transducer (behind the esophageal wall), permitting higher frequency without penetration loss.
  • basicI.B-021
    Which TEE view is best for interrogating the mitral valve for MitraClip placement?
    → Mid-esophageal LAX (125–135°) and intercommissural views (50–70°). Real-time 3D TEE is central for MitraClip: 3D en-face 'surgeon's view' of the mitral valve is used to align the clip perpendicular to the coaptation line.
  • basicI.B-022
    Which TEE view is best for interrogating the left atrial appendage?
    → Mid-esophageal 2Ch view (90°) and multiple angles from 0–140° with off-axis rotation. LAA velocity is measured with PW at the LAA orifice.
  • basicI.B-023
    What is the primary indication for intraoperative TEE during CABG?
    → 1) Confirmation of adequate air removal from cardiac chambers after cardiopulmonary bypass. 2) Assessment of new regional wall-motion abnormalities suggesting graft failure. 3) Quantification of pre- and post-op MR and other valvular pathology.
  • basicI.B-024
    How is ICE positioned during PFO/ASD closure?
    → ICE catheter is advanced through the femoral vein to the RA and rotated to visualize the interatrial septum. Provides real-time guidance for transseptal puncture (if needed) and confirmation of device position.