How can a tricuspid valve coaptation defect be detected using echocardiography?

Detecting Tricuspid Valve Coaptation Defects on Echocardiography

Tricuspid valve coaptation defects are best detected using 2D transthoracic echocardiography from the apical 4-chamber view in mid-systole, measuring the systolic tenting area and coaptation distance, with 3D echocardiography providing superior en face visualization of all three leaflets simultaneously to identify the exact location and extent of non-coaptation.

Primary Imaging Modality and Views

Transthoracic echocardiography (TTE) with Doppler is the key diagnostic test to assess tricuspid valve morphology and identify coaptation defects 1. The three main TTE views for tricuspid valve visualization are 1:

• Parasternal views: Long-axis view of RV inflow and short-axis view at the level of the aortic valve
• Apical 4-chamber view: Primary view for assessing coaptation defects
• Subcostal views: Modified subcostal view may allow simultaneous visualization of all three leaflets

Specific Measurements for Coaptation Defects

2D Echocardiographic Parameters

In secondary tricuspid regurgitation with impaired coaptation, measure the following from the apical 4-chamber view in mid-systole 1:

• Systolic tenting area: Area between the tricuspid annulus and the tricuspid leaflets body

  • A tenting area >1 cm² indicates severe tricuspid regurgitation 1
  • A tenting area >1.63 cm² predicts residual TR after valve surgery 1

• Coaptation distance: Distance between the tricuspid annular plane and the point of coaptation

  • A tethering distance >0.76 cm predicts residual TR after annuloplasty 1

• Tricuspid annular diameter: Measure in diastole from the 4-chamber view

  • Normal diameter: 28 ± 5 mm
  • Significant dilatation: >21 mm/m² (>35 mm absolute) 1

Contemporary Coaptation Gap Measurements

Recent data from transcatheter edge-to-edge repair studies provide specific coaptation gap measurements 2:

• From transgastric short-axis view:

  • Central anterior-septal region: 8.1 ± 3.1 mm
  • Mid anterior-septal region: 5.2 ± 2.3 mm
  • Central septal-posterior region: 6.6 ± 3.2 mm
  • Mid septal-posterior region: 3.8 ± 2.1 mm

• From RV inflow/outflow view:

  • Anterior region: 4.7 ± 2.4 mm
  • Mid region: 5.2 ± 2.4 mm
  • Posterior region: 4.6 ± 3.0 mm

Advanced Imaging Techniques

3D Transthoracic Echocardiography

Real-time 3D TTE provides superior assessment of coaptation defects 1:

• Unique capability: Obtains short-axis plane of the tricuspid valve allowing simultaneous visualization of all three leaflets moving during the cardiac cycle 1
• Advantages over 2D: Identifies exact location, size, and shape of non-coaptation areas 3, 4
• Quantitative assessment: Provides accurate measurement of vena contracta shape and size for TR severity 3

Important caveat: With 2D echo alone, it is rarely possible to visualize all three leaflets simultaneously (usually only from modified subcostal view), so designation of individual leaflets should be done with caution unless simultaneous view of all three cusps is obtained 1

3D Transesophageal Echocardiography

3D TEE provides more detailed anatomical information of the tricuspid valve apparatus 1:

• Useful for identifying specific mechanisms of coaptation failure
• Essential for pre-procedural planning for transcatheter interventions 5, 6
• TEE at 0 degrees in basal transoesophageal and esogastric junction planes visualizes the tricuspid valve 1

Mechanisms of Coaptation Defects to Identify

The most common cause of coaptation defects is secondary (functional) TR rather than primary valve disease 1:

• RV and/or tricuspid annular dilatation: Due to left-sided heart disease, pulmonary hypertension, congenital defects, or cardiomyopathy 1
• Papillary muscle displacement and leaflet tethering: Results from progressive RV remodeling 1
• Loss of annular saddle shape: Annulus becomes flat, planar, and distorted 1
• Reduced annular contraction: Normal contraction is 25% decrease in annular area in systole 1

Less common primary causes include 7, 8:

• Valvular retraction (carcinoid disease)
• Asymmetrically short tendinous cords tethering the septal leaflet
• Rheumatic cardiopathy
• Traumatic rupture

Clinical Pitfalls

• Absence of systolic valvular coaptation always indicates advanced stage of severe TR 7
• Leaflet mobility assessment is critical: In contemporary series, 69% have mildly restricted leaflets and 7% have moderately restricted leaflets 2
• Non-trileaflet anatomy is common: 28% of patients have non-trileaflet valves, with 21% having ≥4 leaflets 2
• Etiology matters: 91% functional, 7% mixed, 2% lead-induced in contemporary populations 2