วันเสาร์ที่ 13 มิถุนายน พ.ศ. 2569

Perioperative Transesophageal Echocardiography (TEE)

Perioperative Transesophageal Echocardiography (TEE)

Overview

TEE เป็น advanced hemodynamic monitoring tool ที่สำคัญใน perioperative care โดยเฉพาะ:

  • High-risk noncardiac surgery
  • Hemodynamic instability
  • Major vascular surgery
  • Transplant surgery
  • Trauma
  • Pulmonary hypertension
  • Embolic phenomena

ให้ข้อมูล real-time เกี่ยวกับ:

  • Cardiac function
  • Volume status
  • Valvular pathology
  • Emboli
  • Aortic pathology

Major Advantages of TEE

  • Real-time bedside cardiac imaging
  • Rapid diagnosis of shock etiology
  • Dynamic monitoring
  • Detect myocardial ischemia earlier
  • Assess preload/afterload
  • Avoid more invasive monitoring in selected cases

Indications

1. Major noncardiac surgery in severe cardiovascular disease

เช่น:

  • Severe CAD
  • LV dysfunction
  • RV dysfunction
  • Severe valvular disease
  • Pulmonary hypertension

โดยเฉพาะหาก anticipated:

  • Large fluid shifts
  • Major bleeding
  • Hemodynamic instability

2. Unexplained hemodynamic instability

Especially refractory hypotension/shock

3. Procedures with high embolic risk

เช่น:

  • Neurosurgery (venous air embolism)
  • Orthopedic surgery
  • Tumor thrombectomy

4. Major vascular surgery

  • Open aortic surgery
  • EVAR/TEVAR

5. Transplant surgery

  • Lung transplantation
  • Liver transplantation

6. Trauma surgery

Especially blunt chest trauma

Contraindications

Absolute/major relative

  • Esophageal perforation
  • Esophageal stricture
  • Esophageal tumor
  • Active GI bleeding
  • Severe cervical spine injury

Potential Complications

Serious complications rare (~0.08%)

Possible complications:

  • Esophageal injury
  • Oropharyngeal injury
  • Tongue ischemia/edema
  • Dental trauma
  • GI perforation

Prevention of Injury

  • Bite guard
  • Adequate lubrication
  • Gentle insertion
  • Midline probe positioning
  • Frequent mouth checks during long surgery

Basic TEE Examination

“5 Vs” approach in unstable patients

1. Volume status

2. Vascular resistance

3. Ventricular function

4. Valvular function

5. Venue-specific pathology

Key TEE Views

Most important views

1. Transgastric LV short-axis (TG SAX)

Most useful overall view

Best for:

  • LV preload
  • Global LV function
  • RWMA detection

2. Midesophageal 4-chamber (ME 4C)

Best for:

  • RV function
  • Chamber size
  • MR/TR

3. Midesophageal long-axis (ME LAX)

Best for:

  • LVOT
  • Aortic valve
  • Mitral valve

Volume Status Assessment

Hypovolemia

TEE findings:

  • Small LV cavity
  • Hyperdynamic LV
  • Decreased LVEDV
  • “Kissing papillary muscles”

Important:
Assess LV size at END-DIASTOLE

Hypervolemia

TEE findings:

  • Atrial enlargement
  • RV dilation
  • Septal flattening
  • IVC dilation
  • Worsening TR

Fluid Responsiveness

Serial TEE assessment can guide:

  • Goal-directed fluid therapy
  • Dynamic preload evaluation

Distinguishing Hypovolemia vs Vasodilation

Both may show:

  • Hyperdynamic LV
  • Low end-systolic volume

Key distinction:

Hypovolemia

↓ LV end-diastolic volume

Low SVR

Normal/increased LVEDV

Ventricular Function

Global LV systolic function

Qualitative assessment:

  • Hyperdynamic
  • Normal
  • Mild/moderate/severe dysfunction

LV dysfunction findings

  • LV dilation
  • Reduced wall thickening
  • Reduced inward motion
  • Spherical LV shape
  • Functional MR

Regional Wall Motion Abnormalities (RWMA)

Important for intraoperative ischemia detection

Assessed in TG SAX view

Wall motion grading

Finding

Meaning

Normal

Normal contraction

Hypokinetic

Reduced contraction

Akinetic

No contraction

Dyskinetic

Paradoxical outward motion

Causes of RWMA

Acute

  • Myocardial ischemia/infarction

Chronic

  • Old MI
  • Cardiomyopathy
  • LBBB
  • Hibernating myocardium

Right Ventricular Function

Critical in:

  • Pulmonary hypertension
  • PE
  • RV infarction
  • Lung transplantation

RV dysfunction findings

  • RV dilation
  • Reduced RV free-wall motion
  • Functional TR
  • Septal shift

Estimation of Pulmonary Artery Pressure

Using TR jet velocity:

PASP ≈ 4V2 + CVP

(V = peak TR velocity)

Cardiac Output Estimation

Using LVOT VTI:

SV = VTILVOT x Cross-Sectional AreaLVOT

CSALVOT = 0.785 x (diameterLVOT)2

Then:
CO = SV × HR

LV Diastolic Dysfunction

May explain:

  • HFpEF
  • Pulmonary edema with preserved EF

TEE parameters:

  • Mitral inflow
  • Tissue Doppler
  • Pulmonary venous flow

Valvular Assessment

TEE evaluates:

  • MR
  • MS
  • AR
  • AS
  • TR
  • Vegetation
  • Chordal rupture

Mitral Regurgitation (MR)

TEE findings:

  • Color Doppler jet
  • Vena contracta
  • Eccentric jet
  • LA enlargement

Important Pearl

Functional/ischemic MR is dynamic:
severity changes with:

  • Loading conditions
  • Ischemia
  • LV dilation

Systolic Anterior Motion (SAM)

Associated with:

  • LVOT obstruction
  • Posteriorly directed MR jet

Worsened by:

  • Hypovolemia
  • Inotropes
  • Hypotension

Aortic Stenosis (AS)

TEE findings:

  • Calcified immobile leaflets
  • Increased Doppler gradient

Aortic Regurgitation (AR)

Severity assessed by:

  • Jet width/LVOT ratio
  • Vena contracta
  • Holodiastolic flow reversal

Mitral Stenosis (MS)

TEE findings:

  • Thickened valve
  • Restricted opening
  • High transmitral gradient
  • LA enlargement
  • SEC/thrombus

Venue-Specific Uses

Major vascular surgery

Aortic cross-clamping

TEE detects:

  • LV failure
  • RWMA
  • Afterload increase

After unclamping

TEE evaluates:

  • Hypovolemia
  • Myocardial dysfunction

Lung transplantation

TEE monitors:

  • RV function
  • Volume status
  • Pulmonary vein anastomosis

Liver transplantation

TEE evaluates:

  • Vasodilation
  • RV failure
  • Volume shifts
  • Embolic phenomena

Renal cell carcinoma with IVC extension

TEE useful for:

  • Tumor extent
  • RA involvement
  • Embolization
  • Residual tumor

Trauma Surgery

TEE rapidly detects:

  • Tamponade
  • Aortic dissection
  • Myocardial contusion
  • Hypovolemia

Cardiac Tamponade Findings

TEE signs:

  • RA collapse
  • RV collapse
  • Pericardial effusion

RA collapse:
more sensitive

RV collapse:
more specific

Aortic Dissection

TEE highly sensitive for thoracic dissection

Limitation:
poor visualization of distal ascending aorta/proximal arch

Venous Air Embolism

High-risk neurosurgery:

  • Sitting position
  • Venous sinus surgery

TEE is most sensitive monitor

PFO Detection

Bubble study:
agitated saline injection

Used before:

  • Neurosurgery
  • Orthopedic surgery
  • Embolic-risk procedures

Orthopedic Surgery

TEE may detect:

  • Fat emboli
  • Cement emboli
  • Air emboli

Usually clinically insignificant unless massive

Laparoscopic Surgery

TEE useful in:

  • Severe HF
  • Pulmonary hypertension
  • Severe valvular disease

Because pneumoperitoneum alters:

  • Hemodynamics
  • Filling pressures

Important Clinical Pearls

  • TEE provides rapid real-time diagnosis of shock etiology
  • TG SAX view is the single most useful intraoperative view
  • “Kissing papillary muscles” strongly suggest hypovolemia
  • RWMA may precede ECG ischemic changes
  • RV dysfunction is critical in pulmonary hypertension and PE
  • Functional MR changes dynamically with loading conditions
  • TEE is highly sensitive for air embolism
  • Bubble study important before high embolic-risk surgery
  • TEE can rapidly diagnose tamponade and aortic dissection
  • Serial TEE assessment more valuable than isolated images

 

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