Obstetric Topic 11. Pregnancy and cardiovascular diseases

I. Basic Concepts and Risk

Importance

• Pregnancy with cardiovascular disease = high-risk pregnancy because pregnancy physiology stresses the heart.
• Mechanism: ↑ plasma volume + ↑ HR + ↑ CO + hypercoagulability → decompensation in limited cardiac reserve.
• Danger periods: late pregnancy, labor/delivery and early postpartum due to rapid venous return/CO changes.
• Common groups: congenital heart disease, rheumatic/valvular disease, arrhythmias and postpartum/peripartum dilated cardiomyopathy.

Risk Assessment

• Preconception/early pregnancy assessment: diagnosis, repair status, symptoms, O2 saturation, ECG, echo, ventricular function, valve gradients, pulmonary pressure and aortic diameter.
• NYHA classification: functional risk assessment.

• Class I: No limitation/no cardiac decompensation → low risk.
• Class II: Mild limitation, comfortable at rest → moderate risk.
• Class III: Marked limitation, comfortable at rest → high risk, relative contraindication.
• Class IV: Symptoms at rest → extreme risk, absolute contraindication.

• Pregnancy contraindicated/highest-risk lesions: pulmonary HT/Eisenmenger syndrome, severe mitral/aortic stenosis, severe LV dysfunction (EF <30%), NYHA IV, previous peripartum cardiomyopathy with residual dysfunction, severe aortic dilatation.
• mWHO classification may also be used for specialist risk stratification, but NYHA is the key oral-exam classification here.

II. Common Cardiovascular Diseases

Congenital Heart Disease

• Examples: ASD, VSD, patent ductus arteriosus, tetralogy of Fallot.
• Corrected simple defects in childhood are usually well tolerated if no residual pulmonary HT or ventricular dysfunction.
• Cyanotic/unrepaired disease → maternal hypoxemia, miscarriage, fetal growth restriction and preterm birth risk.
• Maternal congenital heart disease → consider fetal echocardiography because fetal congenital heart disease risk is increased.

Rheumatic Heart Disease and Mitral Stenosis

• Most important rheumatic lesion: mitral stenosis.
• Pathophysiology: narrowed mitral valve → ↑ left atrial pressure → pulmonary venous congestion.
• Pregnancy effect: ↑ blood volume + ↑ HR → shorter diastole → worsening stenosis → cardiac decompensation, pulmonary edema.
• Symptoms/complications: dyspnea, orthopnea, palpitations, AF, HF, thromboembolism and pulmonary HT.
• Management principle: control HR, avoid fluid overload, anticoagulate if AF/left atrial thrombus/previous embolism, specialist valve care if severe.

Arrhythmias

• Evaluation: frequent monitoring with ECG; echo if significant symptoms or structural disease is suspected.
• Benign ectopic beats are common if isolated and no structural disease.
• SVT: vagal maneuvers first if stable; adenosine/beta-blocker may be used when indicated.
• Unstable tachyarrhythmia → synchronized cardioversion is allowed in pregnancy.
• Atrial fibrillation → risk of HF, especially with mitral stenosis; treat with rate/rhythm control and LMWH anticoagulation if indicated.

Other High-Risk Conditions

• Pulmonary HT/Eisenmenger syndrome → very high maternal mortality; pregnancy is contraindicated.
• Eisenmenger: pulmonary vascular disease → right-to-left shunt; hypotension/↓ SVR worsens cyanosis and can cause collapse.
• Postpartum/peripartum dilated cardiomyopathy: new LV systolic dysfunction near term or postpartum → dangerous HF; high recurrence risk if LV function does not recover.
• Aortic disease/Marfan syndrome and ischemic heart disease are less common but high-risk causes of chest pain, dissection or MI.

III. Investigations and Antenatal Management

Monitoring

• Frequent antenatal visits + cardiology counseling; high-risk disease → Pregnancy Heart Team/expert center.
• Monitor: BP, HR, O2 saturation, weight gain, edema, dyspnea, orthopnea, chest pain, palpitations and syncope.
• Investigations: ECG, echocardiography, CBC/electrolytes; BNP/NT-proBNP if HF symptoms are unclear.
• Fetal surveillance: growth scans if maternal cyanosis, HF, hypertension, beta-blocker use or anticoagulation issues.
• Avoid decompensation triggers: anemia, infection, dehydration, fluid overload, excessive weight gain and strenuous exercise.
• Rest and avoid excessive exercise; left lateral position may reduce vena cava compression.

Medication Principles

• Modify medications before/early in pregnancy.
• Rate control/HT: beta-blockers, especially labetalol when appropriate; nifedipine or methyldopa for HT alternatives.
• HF: beta-blocker, diuretic for pulmonary congestion, hydralazine/nitrates, digoxin.
• Anticoagulation: LMWH when anticoagulation is indicated; mechanical valves need individualized specialist strategy.
• Avoid teratogenic/contraindicated drugs: ACE inhibitors, ARBs, ARNI, MRA, SGLT2 inhibitors, statins and DOACs.

IV. Delivery and Postpartum Management

Delivery Planning

• Plan delivery early: place, timing, mode, anesthesia, monitoring and anticoagulation stop/restart.
• Preferred mode: vaginal delivery unless obstetric indication or specific severe cardiac indication for C-section.
• C-section considered in severe HF, severe pulmonary HT, severe aortic disease, unstable maternal status or obstetric indication.
• Analgesia: epidural often useful to reduce pain/tachycardia, but avoid sudden hypotension.
• Second stage may be shortened with vacuum/forceps in selected patients to reduce prolonged Valsalva.
• Fluid management: avoid both overload and hypotension.

Postpartum

• Early postpartum is dangerous: uterine autotransfusion + mobilized edema → ↑ venous return → pulmonary edema/HF.
• Monitor closely for 24-72 h or longer in moderate/high-risk disease.
• Restart anticoagulation according to bleeding risk and indication.
• Emergency red flags: pulmonary edema, unstable arrhythmia, chest pain, syncope, cyanosis or hypoxemia.
• Postpartum follow-up: cardiology review, echo if needed, contraception and future pregnancy counseling.