In a pregnant woman with rheumatic mitral stenosis (mitral valve area <1.5 cm², New York Heart Association functional class III‑IV despite optimal medical therapy), what are the indications, technique, contraindications, potential complications, and post‑procedure management for a transfemoral balloon mitral valvotomy?

Transfemoral Balloon Mitral Valvotomy in Pregnant Women with Severe Rheumatic Mitral Stenosis

Clear Indication

Percutaneous balloon mitral commissurotomy (BMV) is reasonable for pregnant patients with severe mitral stenosis (mitral valve area ≤1.5 cm²) who remain symptomatic with NYHA class III-IV heart failure despite optimal medical therapy with beta-blockers and diuretics, provided valve morphology is favorable. 1

Pre-Procedure Requirements

Patient Selection Criteria

• Severe mitral stenosis must be confirmed: mitral valve area ≤1.5 cm² on echocardiography 1
• Persistent NYHA class III-IV symptoms despite medical therapy with beta-blockers for rate control and diuretics for pulmonary congestion 1
• Favorable valve morphology is essential: minimal leaflet calcification, good leaflet mobility, minimal subvalvular fusion, and minimal commissural calcification 1, 2
• All patients must be managed in a tertiary care center with a dedicated Heart Valve Team including cardiologists, cardiac surgeons, anesthesiologists, and high-risk obstetricians 1, 3

Medical Management Before Considering BMV

• Beta-blockers (metoprolol or propranolol, NOT atenolol) for rate control should be optimized first 1, 3
• Diuretics should be added for pulmonary congestion while avoiding excessive volume depletion that impairs uteroplacental perfusion 2, 3
• Bed rest may provide additional symptomatic benefit 2
• ACE inhibitors and ARBs are absolutely contraindicated throughout pregnancy due to fetal renal dysplasia, oligohydramnios, growth retardation, and skeletal abnormalities 1, 3

Optimal Timing

BMV should preferably be performed after 20 weeks of gestation, which represents the safest period for the fetus in terms of minimizing malformation risk and premature delivery 1, 2

Technique and Procedural Details

Operator and Center Requirements

• The procedure must be performed only by experienced operators with demonstrated low complication rates 1, 2
• Backup cardiac surgery, anesthesiology, and high-risk obstetrics services must be immediately available 1, 2

Radiation Protection

• Abdominal and pelvic shielding is mandatory to minimize fetal radiation exposure 1, 2, 4, 5
• Left ventriculography and hemodynamic measurements should be omitted when possible to reduce fluoroscopy time 2, 5
• Fluoroscopy time should be minimized: reported mean times range from 7.8 to 16.6 minutes in experienced centers 4, 5, 6

Preferred Balloon Technique

• The Inoue balloon technique is particularly advantageous because it keeps the procedure as short as possible 2, 6
• Double-balloon transseptal technique is an alternative with similar efficacy 5

Monitoring During Procedure

• Continuous fetal monitoring must be performed throughout the procedure 2
• Invasive arterial blood pressure monitoring, continuous ECG, and pulse oximetry are essential 7

Expected Outcomes

Hemodynamic Results

• Mitral valve area typically increases from 0.8-0.9 cm² to 1.7-2.4 cm² 4, 5, 6, 8, 9
• Mean mitral gradient decreases from 17-22 mmHg to 5-6 mmHg 5, 6, 9
• Left atrial pressure falls from 28-29 mmHg to 14 mmHg 5, 9
• Immediate symptomatic improvement by at least one NYHA functional class occurs in all successful cases 6, 8

Maternal Outcomes

• Success rate approaches 98-100% in experienced centers 4, 8, 9
• At end of pregnancy, 98% of patients are in NYHA class I or II 8
• Normal vaginal delivery occurs in 88-95% of cases 4, 6, 8, 9

Fetal Outcomes

• Mean gestational age at delivery is 38 weeks 8
• Preterm delivery occurs in approximately 13% of cases 8
• Mean birth weight is 2.3-2.8 kg 4, 8
• Long-term follow-up (up to 44 months) shows normal growth and development in children with no clinical abnormalities 8, 9

Potential Complications

Major Complications

• Severe traumatic mitral regurgitation requiring emergency surgery occurs in approximately 5% of cases, which is particularly dangerous for the fetus under cardiopulmonary bypass 2, 9
• Cardiac tamponade and embolic events are very rare 2

Surgical Backup Risk

• Open heart surgery during pregnancy carries 30-40% fetal mortality and up to 9% maternal mortality 1, 3

Absolute Contraindications

• Unfavorable valve morphology (severe leaflet calcification, thickening, immobility, severe subvalvular fusion, commissural calcification) makes BMV high-risk 1, 2
• Presence of left atrial thrombus on transesophageal echocardiography 3
• More than moderate (≥3+) mitral regurgitation 9

Management When BMV is Contraindicated

For patients with severe mitral stenosis and unfavorable valve morphology, valve intervention is reasonable only if there are refractory NYHA class IV heart failure symptoms unresponsive to medical therapy. 1 In this scenario, mitral valve replacement under controlled surgical conditions may be safer than attempting high-risk BMV, but this carries the significant 30-40% fetal mortality and up to 9% maternal mortality noted above. 1, 3

Surgery should be carefully planned with the Heart Valve Team to determine optimal timing, using high pump flows, normothermic perfusion, shortest possible pump time, and continuous fetal monitoring. 1 The period between 20-28 weeks of pregnancy appears safest for the fetus in terms of malformation and premature delivery risk. 1

Post-Procedure Management

Immediate Post-Procedure

• Repeat echocardiography should be performed to assess mitral valve area, gradient, and degree of mitral regurgitation 8
• Patients should be monitored for at least 24 hours postpartum due to massive fluid shifts and autotransfusion of 500-1000 mL that can precipitate delayed heart failure decompensation 7

Ongoing Pregnancy Management

• Clinical and obstetric evaluations every 2 weeks to assess symptoms and fetal growth 4
• Continue beta-blockers for rate control as needed 1, 3
• Diuretics should be used cautiously to avoid excessive volume depletion 3

Delivery Planning

• Vaginal delivery is preferred unless obstetric indications dictate cesarean section 3
• Assisted delivery (forceps or vacuum) should be used to avoid Valsalva maneuvers during second-stage labor in patients with residual severe disease 7
• Invasive hemodynamic monitoring should continue for at least 24 hours postpartum 7

Critical Pitfalls to Avoid

• Never perform BMV prophylactically or in patients with good functional tolerance without pulmonary hypertension 2
• Never attempt BMV before 20 weeks of gestation unless life-threatening maternal deterioration occurs 1, 2
• Never perform the procedure in centers without immediate cardiac surgical backup 1, 2
• Never use single-shot spinal anesthesia in patients with severe mitral stenosis due to risk of catastrophic hypotension from abrupt sympathetic blockade; use slow, titrated epidural instead 7
• Never administer methylergonovine for postpartum uterine atony in cardiac patients due to risk of marked vasoconstriction and hypertension; use slow intravenous oxytocin (<2 U/min) instead 7
• Never assume adequate medical therapy has been attempted without optimized beta-blocker dosing and appropriate diuretic use 1, 2