From the Research
Assessing and managing pulmonary vasculature responsiveness in patients with severe mitral regurgitation (MR) with preserved left and right ventricular function requires a systematic approach, starting with a milrinone challenge to evaluate pulmonary vascular reactivity, as recommended by recent studies 1.
Key Considerations
- The milrinone challenge involves administering milrinone, a phosphodiesterase inhibitor, to assess the responsiveness of the pulmonary vasculature.
- This approach is crucial in patients with severe MR and normal left ventricular ejection fraction (LVEF) and right ventricular function, as it helps identify those who may benefit from targeted therapies to reduce pulmonary pressures.
- The challenge is typically performed during right heart catheterization, allowing for the measurement of pulmonary artery pressures, pulmonary vascular resistance (PVR), and cardiac output before and after milrinone administration.
Management Strategy
- For patients with elevated PVR (>3 Wood units) and a positive response to the milrinone challenge, consider preoperative treatment with phosphodiesterase-5 inhibitors like sildenafil (20 mg three times daily) or endothelin receptor antagonists like bosentan (62.5 mg twice daily, increasing to 125 mg twice daily after 4 weeks) for 2-3 months before mitral valve intervention, as supported by studies 2.
- Regular echocardiographic monitoring every 3-6 months is essential to assess right ventricular function and pulmonary pressures, as well as to guide adjustments in treatment.
- The underlying mechanism involves chronic MR causing increased left atrial pressure, pulmonary venous congestion, and eventually pulmonary arterial remodeling, which can become irreversible if not addressed promptly, highlighting the importance of early intervention 3.
Clinical Implications
- The use of a milrinone challenge and subsequent targeted therapies can help reduce perioperative right heart failure risk by decreasing pulmonary pressures, ultimately improving outcomes in patients with severe MR and preserved ventricular function.
- Global longitudinal strain (GLS) may also be a useful parameter in predicting postoperative outcomes, including survival and left ventricular function, as suggested by recent meta-analyses 1.