Why might a patient develop severe tricuspid regurgitation and an enlarged right ventricle after mitral valve repair?

Causes of Severe Tricuspid Regurgitation and Right Ventricular Enlargement After Mitral Valve Repair

Severe tricuspid regurgitation (TR) and right ventricular (RV) enlargement following mitral valve repair most commonly result from untreated pre-existing functional TR that progresses due to persistent RV remodeling, even after correction of the left-sided valve lesion. 1

Primary Mechanisms

• Untreated functional TR at time of mitral surgery: If moderate TR is present before mitral valve repair but not addressed during surgery, it may progress to severe TR in up to 62% of patients within 5 years 2

• Tricuspid annular dilation: Even mild-to-moderate TR with annular dilation (≥40 mm or >21 mm/m²) at the time of mitral surgery can progress to severe TR if left untreated 1

• Right ventricular remodeling and dysfunction: Persistent RV dysfunction following mitral valve repair can lead to progressive TR due to ongoing ventricular dilation and geometric changes 1

• Pulmonary hypertension: Residual pulmonary hypertension after mitral valve repair can contribute to RV pressure overload, leading to RV dilation and functional TR 1

Contributing Factors

• Atrial fibrillation: A significant independent predictor for new severe TR after mitral valve surgery (HR 2.119) 3

• Pre-existing moderate TR: Strong independent predictor (HR 2.401) for progression to severe TR after mitral valve surgery 3

• Rheumatic heart disease: Patients with rheumatic etiology are particularly susceptible to TR progression after mitral valve surgery 3

• Pacemaker leads: Transvenous pacemaker leads crossing the tricuspid valve can contribute to TR progression 1

• Right ventricular ischemia: An often overlooked cause that can lead to RV dysfunction, remodeling, and functional TR 4

Pathophysiological Sequence

1. Initial RV pressure/volume overload: Caused by mitral valve disease leads to RV dilation 1

2. Tricuspid annular dilation: Results from RV enlargement, causing leaflet tethering and reduced coaptation 1

3. Persistent RV remodeling: Even after successful mitral valve repair, RV remodeling may continue if significant TR was not addressed 2, 5

4. Progressive TR: Creates a vicious cycle of further RV volume overload, dilation, and worsening TR 1, 5

Clinical Implications

• Patients who develop severe TR after mitral valve repair show increased need for diuretics (23.9% vs 7.3% in those without severe TR) 3

• Echocardiography typically reveals larger RV dimensions and higher pulmonary artery pressures in these patients 3

• The American College of Cardiology recommends early identification of RV dysfunction through echocardiography, evaluating contractility, dilation, and pulmonary pressures 6

Prevention Strategies

• Concomitant tricuspid repair: Should be performed during initial mitral valve surgery when:

  • Severe TR is present 1
  • Moderate TR is present 1
  • Even mild TR with annular dilation ≥40 mm or >21 mm/m² 1

• Ring annuloplasty: Preferred technique for tricuspid repair, with better long-term results than suture annuloplasty (10% vs 20-35% residual TR at 5 years) 1

• Early intervention: Address TR before RV dysfunction becomes irreversible 1

Management of Established Post-Repair TR

• Medical therapy: Diuretics can be useful for patients with severe TR and signs of right-sided heart failure 1

• Reoperation considerations: Reoperation for isolated TR after previous mitral valve surgery carries high risk (perioperative mortality 10-25%) and should be considered before severe RV dysfunction develops 1

• Monitoring: Continuous monitoring of heart rate, rhythm, blood pressure, and oxygen saturation is recommended in patients with RV dysfunction 6

Remember that addressing moderate or even mild TR with annular dilation at the time of initial mitral valve surgery is crucial for preventing the development of severe TR and RV enlargement postoperatively 1.