How should paravalvular mitral regurgitation (MR) be assessed using intraoperative echocardiography during valve surgery?

Intraoperative Echocardiographic Assessment of Paravalvular Mitral Regurgitation

Intraoperative transesophageal echocardiography (TEE) should be used immediately after mitral valve surgery to detect paravalvular regurgitation, with the critical understanding that small, insignificant paravalvular leaks are commonly observed and should not prompt immediate reoperation, while moderate or greater paravalvular MR requires surgical correction. 1

Key Assessment Principles

Timing and Loading Conditions

• Perform TEE assessment immediately after cardiopulmonary bypass to evaluate for technical problems including paravalvular regurgitation and abnormal leaflet motion 1
• Reproduce representative loading conditions using volume or vasopressors when assessing the adequacy of repair, as general anesthesia causes hemodynamic unloading that can underestimate MR severity 1
• The unloading effects of general anesthesia make intraoperative assessment potentially misleading compared to preoperative conditions 1

Imaging Approach for Paravalvular MR

Use short-axis views of the left ventricular outflow tract (LVOT) just apical to the inflow edge of the prosthesis as the primary imaging plane, with gastric views for confirmation 1

• Three-dimensional TEE provides superior localization and sizing of paravalvular defects compared to 2D TEE, correlating more closely with surgical findings 2
• 3D TEE accurately identifies the exact site and size of paravalvular leakage, which is valuable when the heart is devoid of blood during surgery 2

Clinical Significance and Management Thresholds

Immediate Post-Bypass Findings

• Small, insignificant central or paravalvular leaks are commonly observed immediately after cardiopulmonary bypass and should not be a cause for concern 1
• This represents a critical pitfall: do not overreact to trivial paravalvular jets seen immediately post-bypass 1

Severity-Based Decision Making

Moderate paravalvular MR should be corrected at the time of valve surgery if this can be performed without high operative risk 3

• Mild paravalvular MR should probably also be repaired if low-risk correction is feasible, as some cases progress over time 3
• In one series, 2 of 6 patients with mild paravalvular MR and 2 of 2 patients with moderate paravalvular MR deteriorated clinically and echocardiographically at mean follow-up of 16.3 months 3

Comprehensive Post-Repair Assessment

Beyond paravalvular regurgitation, the complete intraoperative TEE examination must evaluate:

• Residual valvular MR severity 1
• Systolic anterior motion of valve leaflets, which occurred in 9.1% of repairs and resolved with hemodynamic correction in 5.6% without further intervention 4
• Restriction of mitral opening with stenosis 1
• Left ventricular function to detect potential injury to the left circumflex coronary artery from annular sutures 1
• Aortic valve function to identify tethering of aortic cusps by mitral annular sutures 1

Critical Pitfalls to Avoid

• Do not rely solely on intraoperative TEE for the decision to operate, as hemodynamic changes during anesthesia lead to underestimation of MR severity; surgical decisions should be made preoperatively based on symptoms and preoperative testing 1
• Do not dismiss all paravalvular jets as insignificant—while small leaks are common and benign, moderate or greater paravalvular MR requires intervention 1, 3
• Ensure comprehensive examination of surrounding structures, as iatrogenic complications (circumflex injury, aortic valve tethering) can occur and must be detected before leaving the operating room 1

Follow-Up Considerations

Patients with mild paravalvular MR left after surgery require careful follow-up with serial clinical and echocardiographic examinations, as progression can occur 3. Predischarge transthoracic echocardiography may show discrepancies compared to intraoperative TEE findings (12.9% with >1 grade difference in one series), necessitating correlation between modalities 4.