What are the red flag signs and management options for cardiac disease in pregnancy?

Red Flag Signs of Cardiac Disease in Pregnancy

Pregnant women with cardiac disease require immediate recognition of life-threatening red flags, with pulmonary hypertension, severe left ventricular outflow obstruction, and NYHA class III/IV symptoms representing the highest-risk conditions that demand urgent intervention or pregnancy avoidance. 1

Highest-Risk Red Flags (Contraindications to Pregnancy)

Pulmonary Hypertension

• Maternal mortality of 17-50%, making this the single most dangerous cardiac condition in pregnancy 1
• Mean pulmonary artery pressure ≥25 mmHg at rest defines pulmonary hypertension 1
• Life-threatening rise in pulmonary vascular resistance occurs particularly in peripartum and postpartum periods, causing pulmonary thrombosis or fibrinoid necrosis 1
• In Eisenmenger syndrome, right-to-left shunting increases due to systemic vasodilation, worsening cyanosis and decreasing pulmonary blood flow 1
• These patients should be counseled against pregnancy 1

Severe Left Ventricular Outflow Tract Obstruction

• Fixed outflow tract resistance cannot accommodate increased cardiac output from expanded plasma volume 1
• Severe aortic stenosis can cause symptoms even in previously asymptomatic women 1
• All symptomatic patients with severe AS or asymptomatic patients with impaired LV function should be counseled against pregnancy 1

Advanced Heart Failure

• Any patient reaching NYHA class III or IV during pregnancy is at high risk regardless of underlying condition, indicating no remaining cardiovascular reserve 1
• Heart failure is often progressive, particularly in second and third trimesters 1

Critical Warning Signs Requiring Urgent Evaluation

Acute Decompensation Signs

• Pulmonary edema, particularly when mitral stenosis is unknown or if atrial fibrillation occurs 1
• New or worsening dyspnea beyond normal pregnancy-related breathlessness 1
• Symptoms developing in women with previously mild disease (e.g., mild mitral stenosis can become symptomatic during pregnancy) 1

Arrhythmia Red Flags

• Atrial fibrillation carries additional risk of thromboembolic events (occurs in <15% of mitral stenosis cases but is life-threatening) 1
• Life-threatening arrhythmias in patients with atrial switch operations (Mustard/Senning repair) or congenitally corrected transposition 1
• Sustained tachycardia causing hemodynamic compromise or fetal hypoperfusion 2

Valvular Disease Warning Signs

• **Moderate or severe mitral stenosis (valve area <1.5 cm²)** with symptoms or pulmonary hypertension (systolic PAP >50 mmHg) 1
• Severe tricuspid regurgitation with heart failure 1
• Development of symptoms in previously asymptomatic severe aortic stenosis 1

Acute Coronary Syndrome

• Maternal mortality 5-10% with ACS in pregnancy, highest during peripartum period 1
• ST-elevation requires immediate referral for primary PCI, not thrombolysis 1
• Coronary dissection must be considered (thrombolysis may cause subplacental bleeding) 1

Ventricular Dysfunction

• Ejection fraction <40% or irreversible decline in right ventricular function (occurs in 10% of systemic RV patients) 1
• Oxygen saturation <85% at rest in complex congenital heart disease 1
• Severe pulmonary regurgitation identified as independent predictor of maternal complications 1

High-Risk Structural Lesions

Congenital Heart Disease Red Flags

• Cyanotic lesions with oxygen saturation <85% 1
• Fontan circulation with non-optimal circuit 1
• Unrepaired complex congenital heart disease 3
• Mechanical prosthetic valves (hypercoagulable state of pregnancy) 3

Aortic Pathology

• Ascending aorta dilatation >45 mm (caesarean delivery indicated) 1
• Marfan syndrome with aortic diameter 40-45 mm (caesarean may be considered) 1
• Fragile aortas at risk for dissection 1

Management Algorithm for Red Flag Presentations

Immediate Actions for Hemodynamic Instability

• Electrical cardioversion for ventricular tachycardia or unstable supraventricular tachycardia 2, 4
• Urgent echocardiography for any unexplained or new cardiovascular signs/symptoms 1
• Transfer to specialized tertiary center with multidisciplinary cardiac-obstetric team 1

Monitoring Requirements for High-Risk Patients

• Monthly or bimonthly cardiac evaluations including echocardiography for severe stenotic lesions, systemic RV function, or severe pulmonary regurgitation 1
• Continuous assessment of symptoms, pulmonary artery pressure, and ventricular function 1
• Holter monitoring if arrhythmias suspected 2

Intervention Thresholds

• Percutaneous mitral commissurotomy indicated for NYHA class III/IV or systolic PAP >50 mmHg despite optimal medical therapy (after 20 weeks gestation) 1
• Primary PCI preferred over thrombolysis for acute coronary syndrome 1
• Emergency delivery should be considered if gestational age ≥28 weeks before necessary cardiac surgery 1

Critical Pitfalls to Avoid

• Missing pulmonary hypertension or mitral stenosis by attributing dyspnea solely to normal pregnancy changes 1
• Failing to recognize that previously asymptomatic severe stenotic lesions can decompensate during pregnancy 1
• Using amiodarone except when all other therapies have failed (fetotoxic effects) 2
• Administering ACE inhibitors, ARBs, or renin inhibitors (absolutely contraindicated) 1
• Delaying cardioversion in hemodynamically unstable arrhythmias 2, 4
• Performing thrombolysis without considering coronary dissection as differential 1

Delivery Planning for Red Flag Conditions

Caesarean Section Indications

• Ascending aorta >45 mm 1
• Severe aortic stenosis 1
• Eisenmenger syndrome 1
• Severe heart failure 1
• Moderate/severe mitral stenosis with NYHA class III/IV or pulmonary hypertension despite medical therapy 1

Vaginal Delivery Preferred

• Most cardiac patients without above contraindications 1
• Mild mitral stenosis 1
• Moderate/severe mitral stenosis in NYHA class I/II without pulmonary hypertension 1