What initial testing should be ordered for a pregnant woman experiencing heart palpitations?

Initial Testing for Pregnant Women with Heart Palpitations

For pregnant women experiencing heart palpitations, the initial testing should include a 12-lead ECG and Holter monitoring, along with a thorough cardiac assessment including echocardiography to evaluate cardiac structure and function. 1

Diagnostic Algorithm

Step 1: Initial Assessment

• Obtain a detailed personal and family history, focusing on cardiomyopathies, Marfan syndrome, congenital heart disease, juvenile sudden death, long QT syndrome, and catecholaminergic ventricular tachycardia 1
• Ask specifically about possible sudden deaths in the family 1
• Assess for symptoms of dyspnea, which is important for diagnosis and prognosis of valve lesions and heart failure 1
• Perform a thorough physical examination considering physiological changes of pregnancy, including auscultation for new murmurs or changes in existing murmurs 1
• Measure blood pressure in left lateral recumbency using a standardized method 1
• Check for proteinuria, especially with history or family history of hypertension or pre-eclampsia 1

Step 2: First-line Testing

• 12-lead ECG to evaluate for arrhythmias and structural heart disease 1
  • Note that normal pregnancy findings include 15-20° left axis deviation, transient ST segment and T wave changes, Q wave and inverted T waves in lead III, attenuated Q wave in lead AVF, and inverted T waves in leads V1, V2, and occasionally V3 1
• Holter monitoring for patients reporting symptoms of palpitations to document the arrhythmia 1, 2
• Echocardiography for all pregnant women with palpitations to assess cardiac structure and function 1
  • This is the preferred screening method during pregnancy as it does not involve radiation exposure 1

Step 3: Additional Testing Based on Initial Findings

• Exercise testing (submaximal to 80% of predicted maximum heart rate) to assess functional capacity, chronotropic response, blood pressure response, and exercise-induced arrhythmias 1
• Transoesophageal echocardiography if additional information is needed, particularly for complex congenital heart disease 1
  • This is relatively safe during pregnancy but requires consideration of aspiration risk and potential need for sedation 1

Special Considerations

Radiation Exposure

• Procedures involving radiation should be delayed until after completion of major organogenesis (>12 weeks after menses) if possible 1
• Radiation exposure <50 mGy to the pregnant woman has not been associated with increased fetal risk of congenital malformations, intellectual disability, growth restriction, or pregnancy loss 1
• There may be a small increase in risk of childhood cancer (1:2000 vs. 1:3000) with radiation exposure 1

Laboratory Testing

• Normal pregnancy does not elevate BNP or troponin levels; if elevated, consider pathological causes 1
• D-dimer testing is not recommended during pregnancy 1
• Cholesterol levels may be up to five times elevated in pregnancy and should not be routinely checked 1

Multidisciplinary Approach

• For complex cases or confirmed arrhythmias, involve a multidisciplinary team including cardiologists, obstetricians, maternal medicine specialists, and anesthesiologists 1, 3
• Early involvement of the pregnancy heart team can facilitate appropriate treatment decisions 2

Management Considerations

• Haemodynamically unstable arrhythmias warrant urgent electrical cardioversion, which is safe during all stages of pregnancy 1, 4
• For stable patients with confirmed arrhythmias, beta-1 selective blockers (excluding atenolol) are recommended for heart rate control 1
• Digoxin should be considered for heart rate control if beta-blockers are ineffective or not tolerated 1
• Many anti-arrhythmic medications are safe in pregnancy, but require careful selection 2, 3

Pitfalls to Avoid

• Do not dismiss palpitations in pregnancy as always benign; while many are due to normal physiological changes or benign ectopic beats, some may indicate serious underlying cardiac conditions 2, 3
• Do not confuse normal pregnancy-related ECG changes with pathological findings 1
• Avoid unnecessary radiation exposure, but do not withhold essential diagnostic procedures when indicated 1
• Do not assume that all palpitations require treatment; isolated ectopic beats typically do not need intervention 2, 3