What is the recommended approach for assessing the mitral valve using an echocardiogram (echo-cardiogram)?

Echocardiographic Assessment of the Mitral Valve

Transthoracic echocardiography (TTE) is the first-line imaging modality for comprehensive mitral valve assessment, with transesophageal echocardiography (TEE) reserved for cases of suspected or confirmed dysfunction, inadequate TTE imaging quality, or when detailed pre-operative planning is required. 1

Initial Imaging Approach

Transthoracic Echocardiography (TTE)

• Begin with 2D TTE using multiple standardized views to evaluate all components of the mitral valve apparatus, including the annulus, leaflets, chordae tendineae, papillary muscles, and left ventricular attachments 1, 2
• Essential TTE views include:
  • Parasternal long-axis view (visualizes A2 and P2 scallops; used to diagnose prolapse and measure annular dimensions) 1
  • Parasternal short-axis view (assesses all six scallops and localizes regurgitant jet origin) 1
  • Apical four-chamber view (visualizes A3, A2, and P1 scallops from internal to external) 1
  • Apical two-chamber view (displays P3, A2, and P1 in bi-commissural orientation) 1
  • Multiple off-axis cuts to scan the entire sewing ring and subvalvular apparatus 1

Critical Pitfall in 2D Imaging

• Never diagnose mitral valve prolapse from the apical four-chamber view alone, as the saddle-shaped annulus creates false-positive findings; always confirm prolapse in the parasternal long-axis or apical long-axis views 1

Comprehensive Assessment Components

Valve Morphology

• Document leaflet structure including the six individual scallops (A1, A2, A3 for anterior leaflet; P1, P2, P3 for posterior leaflet from left to right) 1
• Identify specific pathology:
  • Flail leaflet, ruptured papillary muscle, or large coaptation defect (specific for severe mitral regurgitation) 1
  • Leaflet thickening, calcification, or prolapse 1
  • Chordal rupture with visualization from left atrial views or longitudinal cut planes 1
• Measure annular dimensions using parasternal long-axis view; annular dilatation is present when the annulus/anterior leaflet ratio is ≥1.32 1

Functional Assessment

• Evaluate leaflet motion using Carpentier's classification to determine mechanism of regurgitation 2
• Assess coaptation by checking for visible leaks at the coaptation line, which has an upward concavity in the closed position 1
• Measure normal annular contraction, which should show a 25% decrease in annular area during systole 1

Quantitative Parameters for Regurgitation

• Use color Doppler imaging as the primary screening tool, recognizing that jet size depends on technical factors, hemodynamics, LA pressure, and jet direction (eccentric vs. central) 1
• Apply semi-quantitative measures:
  • Vena contracta width (severe if >6 mm) 1
  • Pressure half-time 1
  • Circumferential extent of paravalvular regurgitation (severe if ≥30%) 1
• Calculate quantitative parameters:
  • Effective regurgitant orifice area (EROA; severe if ≥30 mm²) 1
  • Regurgitant volume (severe if ≥60 mL) 1
  • Regurgitant fraction (severe if >50%) 1

Associated Cardiac Parameters

• Document left ventricular size and function to assess impact of regurgitation and guide timing of intervention 1
• Measure left atrial size as a marker of chronicity and hemodynamic burden 1
• Estimate pulmonary artery pressure to evaluate secondary effects of mitral valve disease 1

When to Advance to 3D Echocardiography

3D TTE or TEE Indications

• Use 3D imaging when available for superior visualization of mitral valve morphology, particularly for anterior leaflet defects, commissural involvement, and complex pathology 1
• 3D provides the "en face" surgical view from the atrial perspective, identical to what surgeons see in the operating room 1
• 3D is superior to 2D for assessing the saddle-shaped annulus, which cannot be adequately appreciated with mental reconstruction from 2D views 1
• Display orientation: Always orient the mitral valve with the aortic valve at the 12 o'clock position, regardless of whether viewing from the left atrial or left ventricular perspective 1

3D Advantages for Specific Assessments

• Precise localization of prolapsing segments and anatomic lesions using leaflet segmentation 1
• Quantification of annular geometry, including size, shape, and degree of non-planarity using commercial software 1
• Evaluation of subvalvular apparatus with en face views from the LV perspective showing chordal insertions 1

Transesophageal Echocardiography (TEE)

Specific Indications for TEE

• Proceed to TEE when:
  • TTE image quality is suboptimal or inconclusive 1, 3
  • Suspected or confirmed mitral valve dysfunction requiring detailed assessment 1
  • Pre-operative planning for mitral valve repair or replacement 4, 5, 6
  • Intra-procedural guidance for transcatheter interventions 1

TEE Examination Protocol

• Systematic six-view examination improves identification of mitral segments and precise localization of pathology (96% accuracy vs. 70% with non-systematic approach, p<0.001) 7
• Standard TEE views include:
  • Mid-esophageal five-chamber view 7
  • Mid-esophageal four-chamber view 7
  • Mid-esophageal two-chamber views (anterior, mid, posterior) 7
  • Transgastric short-axis view at 0° (permits assessment of all six scallops) 1
  • Mid-esophageal long-axis view at 120° (shows A2 and P2) 1

TEE vs. TTE Accuracy

• In experienced hands, TTE predicts valve repairability with 97% accuracy, with TEE adding significant information in only rare cases 5
• For degenerative mitral regurgitation, TTE shows 91% agreement with surgical findings for localizing prolapsed segments (kappa 0.81) vs. 93% for TEE (kappa 0.85), without significant incremental value (p=0.40) 5
• However, intraoperative TEE remains essential even when pre-operative TTE is comprehensive 5

Pre-Operative Risk Stratification

Predictors of Unsuccessful Repair

• Primary mitral regurgitation unfavorable features:

  • Large central regurgitant jet 1
  • Severe annular dilatation (>50 mm) 1
  • Involvement of ≥3 scallops, especially with anterior leaflet involvement 1
  • Extensive valve calcification 1
  • Lack of valve tissue (rheumatic disease or endocarditis with large perforation) 1

• Secondary ischemic mitral regurgitation unfavorable features:

  • Mitral diastolic annulus diameter ≥37 mm 1
  • Systolic tenting area ≥1.6 cm² 1
  • Severe functional ischemic mitral regurgitation 1

Prognostic Implications

• Single prolapse of the middle posterior scallop (P2) predicts better postoperative outcome compared to non-P2 lesions (p=0.008) 5
• Mitral replacement predicted by TTE is an independent predictor of long-term postoperative mortality (odds ratio 5.7,95% CI 1.97-16.4, p=0.001) 5

Alternative Imaging Modalities

Cardiac MRI

• Consider cardiac MRI when:
  • Echocardiography is inconclusive or provides discrepant results after eliminating technical errors 1
  • Detailed assessment of valve morphology and function is needed with superior multiplanar capacity 3
  • Accurate quantification of mitral regurgitation is required (MRI shows better correlation with post-surgical LV remodeling: r=0.85, p<0.0001 vs. echo r=0.32, p=0.1) 3
  • Evaluating complex congenital anomalies like double-orifice mitral valve without radiation exposure 3

Cardiac CT and Cinefluoroscopy

• Reserve CT or cinefluoroscopy for cases where leaflet/disc motion is unclear on TTE in prosthetic valves, or when MRI is contraindicated 1
• Avoid CT in young patients with congenital anomalies requiring repeated examinations due to radiation exposure 3