What is the appropriate workup and management for a 17-week pregnant female presenting with dizziness and palpitations in an outpatient primary care (PCP) office?

Workup and Management of Dizziness and Palpitations in a 17-Week Pregnant Patient

Immediate Assessment in the Outpatient Office

Obtain a 12-lead ECG immediately to identify the arrhythmia type and assess for structural heart disease markers such as pre-excitation, prolonged QT interval, or conduction abnormalities. 1, 2

Critical History Elements to Obtain

• Onset and termination pattern: Sudden onset/termination suggests paroxysmal supraventricular tachycardia (SVT), which occurs in 20-44% of pregnancies, while gradual onset suggests sinus tachycardia 3, 1
• Associated symptoms: Syncope or near-syncope suggests serious arrhythmia; chest pain or severe dyspnea indicates hemodynamic compromise requiring immediate ER transfer 1, 2
• Personal cardiac history: Previous arrhythmias, structural heart disease, or congenital heart disease increases risk of sustained tachycardia during pregnancy 3
• Family history: Sudden cardiac death, cardiomyopathy, or inherited arrhythmia syndromes (Long QT, Brugada) warrant close surveillance 3
• Thyroid disease history: Hyperthyroidism can cause or exacerbate arrhythmias in pregnancy 1

Physical Examination Priorities

• Hemodynamic stability assessment: Blood pressure, heart rate, respiratory rate, and mental status to determine if immediate cardioversion is needed 1, 2
• Signs of heart failure: Elevated jugular venous pressure, pulmonary crackles, or peripheral edema may indicate peripartum cardiomyopathy, which can present as early as the last 6 weeks of pregnancy 3, 4
• Thyroid examination: Goiter, tremor, or diaphoresis suggesting thyroid storm 4

Diagnostic Workup Algorithm

In-Office Testing (Immediate)

• 12-lead ECG: Essential to identify arrhythmia type, pre-excitation (which contraindicates AV nodal blockers), or evidence of structural disease 1, 2
• Vital signs with orthostatic assessment: Rule out volume depletion or autonomic dysfunction 2

Outpatient Testing (Within 1-2 Weeks if Stable)

• 24-48 hour Holter monitor: If symptoms persist or recur, to capture arrhythmia episodes 2, 5
• Echocardiogram: Mandatory if arrhythmias are documented to rule out structural heart disease and assess left ventricular function, particularly to exclude peripartum cardiomyopathy 2, 4
• Thyroid function tests: TSH and free T4 to exclude hyperthyroidism as a precipitant 1

Fetal Assessment

• Fetal heart rate monitoring: Sustained maternal tachycardia can cause fetal hypoperfusion, particularly in structural heart disease 4

Management Based on Clinical Presentation

If Hemodynamically Stable with Benign Findings

Most palpitations in pregnancy are benign (isolated ectopic beats or sinus tachycardia) and require only reassurance with avoidance of stimulants such as caffeine, smoking, and alcohol. 3, 6

• Conservative management: Adequate hydration, rest, and reassurance 2
• No antiarrhythmic therapy needed for isolated premature beats or physiologic sinus tachycardia 3, 6

If Documented Supraventricular Tachycardia (Stable)

For acute termination of SVT, attempt vagal maneuvers first (Valsalva, carotid massage), followed by IV adenosine 6 mg rapid push if vagal maneuvers fail, then IV metoprolol if adenosine is ineffective. 3, 2, 4

• Prophylactic therapy (if recurrent or symptomatic): Cardioselective beta-blockers (metoprolol or propranolol) are first-line after the first trimester 3, 4
• Avoid atenolol due to fetal growth restriction risk 4
• Second-line options (if beta-blockers ineffective): Sotalol, flecainide, or propafenone in the absence of structural heart disease 3
• Critical caveat: Never use AV nodal blocking agents (adenosine, beta-blockers, calcium channel blockers) if pre-excitation is present on ECG, as this can precipitate ventricular fibrillation 4

If Hemodynamically Unstable

Immediate electrical cardioversion is indicated for any sustained tachycardia causing hemodynamic instability (hypotension, altered mental status, severe dyspnea), using biphasic shock energy of 120-200 J with the lateral pad placed under breast tissue. 3, 1, 4

• Do not delay cardioversion due to pregnancy concerns; maternal stability is essential for fetal survival 4
• Transfer to emergency department immediately if signs of instability develop 1, 2

When to Refer to Emergency Department

Send immediately to ER if any of the following occur: 1, 2

• Recurrent episodes of dizziness with tachycardia
• Syncope or near-syncope
• Chest pain or severe dyspnea
• Signs of hemodynamic instability (hypotension, altered mental status)
• Documented sustained tachycardia (>30 seconds) on monitoring

When to Refer to Cardiology/Maternal-Fetal Medicine

• Documented arrhythmia on Holter monitor requiring antiarrhythmic therapy 2
• Structural heart disease on echocardiogram 2, 7
• Family history of sudden cardiac death with symptomatic palpitations 3
• Recurrent symptomatic arrhythmias despite initial management 7

Special Pregnancy Considerations

• Peripartum cardiomyopathy should be ruled out in any pregnant woman presenting with new-onset arrhythmias, particularly ventricular tachycardia, during the last 6 weeks of pregnancy or postpartum 3, 4
• Drug pharmacokinetics are altered in pregnancy, requiring careful monitoring if antiarrhythmics are prescribed 4
• Amiodarone should only be used when all other therapies have failed and at the lowest effective dose due to fetal toxicity (FDA Category D) 3, 4
• ACE inhibitors, ARBs, and renin inhibitors are contraindicated throughout pregnancy 3

Common Pitfalls to Avoid

• Do not dismiss palpitations as "normal pregnancy symptoms" without obtaining at least a 12-lead ECG, as new-onset ventricular tachycardia can present during pregnancy 3, 1
• Do not use adenosine or other AV nodal blockers if pre-excitation (delta waves) is visible on ECG 3, 4
• Do not delay cardioversion in unstable patients due to concerns about fetal safety; maternal instability threatens both mother and fetus 4
• Do not prescribe atenolol for any indication in pregnancy due to fetal growth restriction risk 4