Why do patients develop pulmonary hypertension and worsened tricuspid regurgitation after mitral valve repair, and can this improve over time with surgical recovery?

Development of Pulmonary Hypertension and Worsened Tricuspid Regurgitation After Mitral Valve Repair

Pulmonary hypertension and worsened tricuspid regurgitation (TR) after mitral valve repair typically result from afterload mismatch with the recipient's elevated pulmonary pressures, but these conditions usually improve over time as pulmonary resistance decreases during surgical recovery. 1

Mechanisms of Post-Mitral Valve Repair Pulmonary Hypertension and TR

• Immediately after mitral valve repair, right ventricular (RV) cavity size increases due to afterload mismatch with the relatively high pulmonary pressures of the recipient 1
• Tricuspid regurgitation in the first weeks after surgery is usually secondary to this pulmonary hypertension 1
• The surgical technique used for valve repair can influence the occurrence of TR because of alterations in right atrial morphology 1
• Right heart failure is a common and feared complication in the early post-operative period 1

Expected Timeline for Improvement

• Normalization in RV cavity size is expected in the following weeks along with progressive reduction of pulmonary resistances 1
• The severity of TR often decreases spontaneously as pulmonary resistance decreases 1
• Two-thirds of patients show partial recovery of RV longitudinal function during the first year after surgery, even if tricuspid annular plane systolic excursion (TAPSE) remains lower than normal 1
• After successful mitral valve repair, pulmonary hypertension and TR almost always diminish if the tricuspid valve anatomy is not grossly distorted 1, 2

Factors Affecting Recovery and Improvement

• TR is more likely to improve when pulmonary hypertension is severe and the tricuspid valve anatomy is not grossly distorted 2
• Improvement is less likely when there is significant tricuspid annular dilation (≥40 mm or >21 mm/m²) 3
• Functional TR rather than organic tricuspid valve disease is a predictor of TR improvement 2
• The incomplete recovery of RV systolic function can be explained by:
  • Pre-repair pulmonary pressures 1
  • Increased post-repair pulmonary gradient 1
  • Significant tricuspid regurgitation 1
  • Prolonged ischemia time 1

Factors That May Prevent Improvement

• Persistent high pulmonary pressures 1
• Tricuspid annulus enlargement secondary to RV dilation 1
• Papillary muscle dysfunction 1
• Alterations in right atrial contraction with functional impairment of the valvular apparatus 1
• Organic tricuspid valve disease rather than functional TR 3
• Severe right ventricular dysfunction prior to mitral valve repair 4

Monitoring and Management

• Regular echocardiographic follow-up is essential to monitor TR progression and right ventricular function after mitral valve repair 2
• Medical therapies to reduce elevated pulmonary artery pressures might be considered in patients with severe functional TR 1
• Diuretics can be useful for patients with severe TR and signs of right-sided heart failure 1

Common Pitfalls

• Failing to assess the severity of TR and tricuspid annular dimensions before mitral valve surgery 2
• Underestimating the importance of tricuspid valve tethering as a predictor of residual TR after surgery 2
• Not considering concomitant tricuspid valve repair during initial mitral valve surgery when significant TR or annular dilation is present 3

Conclusion

Pulmonary hypertension and worsened TR in the immediate post-operative period after mitral valve repair are common and typically improve over time as pulmonary vascular resistance decreases. However, improvement depends on multiple factors including tricuspid valve anatomy, degree of RV dysfunction, and resolution of pulmonary hypertension.