Cardiac disease in pregnancy
Stem
A 27-year-old woman, 68 kg, at 37 weeks has rheumatic mitral stenosis with a valve area of 1.1 cm² and a mean gradient of 12 mmHg. Over the past month she has developed dyspnea on climbing one flight of stairs. She takes metoprolol, her heart rate is 96 in sinus rhythm, and blood pressure is 108/64 mmHg. She arrives in early spontaneous labor, 3 cm dilated, and her lungs are clear.
Question
How will you manage her labor and delivery?
Ideal answer
HeadlineSevere, symptomatic mitral stenosis, top of the modified WHO scale:1 labor without tachycardia, volume overload or rising pulmonary pressures. I bring cardiology, maternal-fetal medicine and obstetrics together now.
- ICU-level monitoring; continue beta-blocker. A slow rate lengthens diastolic filling across the valve.
- Arterial line, continuous ECG and oximetry; no PA catheter. She is symptomatic; the catheter can trigger arrhythmias, and its wedge overestimates left ventricular filling across a stenotic valve.2
- Early epidural, dosed slowly. Pain-driven tachycardia is the main threat; a gradual block avoids sudden preload drops.2
- Phenylephrine for hypotension, judicious fluids, strict left uterine displacement. It raises pressure without tachycardia; displacement protects venous return.
- Vaginal delivery, assisted second stage, as pushing raises heart rate and pulmonary pressures; cesarean for obstetric indications only.2
Watch for: autotransfusion after delivery raises preload as pulmonary edema risk peaks: several days in a monitored bed.
Breaking down the answer
- Classify the risk out loud — mWHO class IV, where pregnancy is contraindicated, includes severe mitral stenosis, pulmonary arterial hypertension and an ejection fraction below 30% with NYHA III–IV symptoms. Mechanical valves and Fontan circulation are class III.1 Naming the class shows organization.
- Why stenosis decompensates now — cardiac output rises about 50% in pregnancy and up to another 45% in labor.3 A fixed mitral orifice cannot pass that flow without left atrial pressure, and then pulmonary pressure, climbing.
- Which beta-blocker — beta-blockers improve left ventricular filling; atenolol is avoided because of low birth weight.2
- Why early neuraxial — early labor analgesia controls heart rate and slow titration avoids abrupt sympathectomy; careful fluids protect uteroplacental flow without causing pulmonary edema.2 Changes if: cesarean, then I extend the epidural incrementally.
- Know who is high risk — valve area below 1.5 cm², gradient above 5 mmHg, NYHA III–IV, prior pulmonary edema or arrhythmia, stroke, or pulmonary artery systolic pressure above 50 mmHg.2
- Protect the pulmonary vasculature — hypoxia, hypercarbia and acidosis raise pulmonary vascular resistance, so I avoid all three, through labor and any sedation.
- Why it matters — cardiovascular disease is the leading cause of US pregnancy-related death, about 26.5% of the total.4
Follow-up question
Two hours after the epidural, during a strong contraction, she becomes short of breath with an irregular rhythm at 150 bpm. Her SpO2 is 90%, blood pressure 92/58 mmHg, and you hear crackles at both bases.
What is happening, and what do you do?
Follow-up answer
HeadlineNew atrial fibrillation with rapid response causing pulmonary edema: lost atrial kick and filling time across a tight valve. I call cardiology, tell the obstetrician.
Upright with left uterine displacement and oxygen. Hypotensive and hypoxemic means unstable: synchronized cardioversion, safe in pregnancy, with sedation and airway equipment ready. If she stabilizes, IV beta-blockade to 70–90 bpm and furosemide.2 I correct hypoxia and hypercarbia, plan anticoagulation with cardiology and obstetrics because fibrillation with an enlarged atrium is a thromboembolic risk, time heparin around delivery and catheter removal, and reassess the fetal tracing.2 Then lung sounds, saturation and rhythm again; persistent decompensation means discussing assisted delivery.
Pitfalls that cost points
- Treating epidural hypotension with ephedrine or a large crystalloid bolus.
- Choosing a fast single-shot spinal for cesarean in severe stenosis.
Rapid-fire
Q: Why are stenotic valves poorly tolerated late in pregnancy? A: They cannot raise left-sided output to match the expanding plasma volume.2 Regurgitant lesions do better because falling systemic resistance unloads the ventricle.
Q: Which echo measures track valve area during pregnancy? A: Planimetry and pressure half-time; the gradient rises with preload.2
Q: What if she fails medical therapy before term? A: Percutaneous balloon valvuloplasty, ideally after 20 weeks, before the uterus makes access difficult.2
Q: Where does a repaired tetralogy of Fallot sit on the mWHO scale? A: Class II.1
Q: Which aortic size makes Marfan syndrome class IV? A: Aortic dilatation above 45 mm.1
Numbers to know
| Item | Value |
|---|---|
| Cardiac output | +50% in pregnancy, up to +45% more in labor3 |
| High-risk mitral stenosis | Area <1.5 cm², gradient >5 mmHg2 |
| Pulmonary hypertension flag | PA systolic >50 mmHg2 |
| Rate goal in atrial fibrillation | 70–90 bpm2 |
| mWHO IV ventricular function | EF <30% with NYHA III–IV1 |
| Share of US pregnancy-related deaths | 26.5% cardiovascular4 |
Links
- Mitral regurgitation and mitral stenosis, Neuraxial labor analgesia and its complications, Physiologic changes of pregnancy, Atrial fibrillation: new onset and chronic, Pulmonary hypertension and right ventricular failure
- ACOG Practice Bulletin 212, Pregnancy and Heart Disease (2019); modified WHO classification (ESC)
Sources
- 1.Modified World Health Organization (WHO) Classification of Maternal Cardiovascular Risk: Application · CMQCC (Cardiovascular Disease in Pregnancy and Postpartum Toolkit), 2017 · cmqcc.orgReprints the ESC 2011 mWHO table.
- 2.Simulation Patient Design: Case of Mitral Stenosis in L&D (SIMOM 10) · SOAP / OpenAnesthesia (Mahendra and Murugan), 2020 · openanesthesia.orgBackground section on risk stratification, monitoring and peripartum management; the simulation scenario itself is not used.
- 3.Changes in Maternal Physiology During Pregnancy (Update in Anaesthesia 21) · WFSA · resources.wfsahq.org
- 4.Pregnancy and Heart Disease (Practice Bulletin No. 212) · ACOG, 2019 · acog.orgAbstract only (full text is member content); reaffirmed 2025.
Facts on this page were checked against these sources on Oct 15, 2026. Guidelines change; confirm doses against current institutional protocols.