What are the potential life‑threatening causes of sudden chest pain in a pregnant woman undergoing a lower‑segment caesarean section and how should they be evaluated and managed?

Sudden Chest Pain During Caesarean Section: Life-Threatening Causes and Management

In a pregnant woman experiencing sudden chest pain during lower-segment caesarean section, immediately evaluate for pulmonary embolism, acute coronary syndrome, aortic dissection, and peripartum cardiomyopathy, as these represent the most life-threatening causes with significant maternal mortality risk.

Immediate Life-Threatening Differential Diagnosis

Pulmonary Embolism (Most Common Fatal Cause)

• PE is the leading cause of maternal mortality during caesarean section and presents with sudden chest pain, dyspnea, tachycardia (>100 bpm), and tachypnea in >90% of cases 1, 2
• Cardiac arrest from massive PE occurs in up to 23% of high-risk obstetric patients, with sudden cardiovascular collapse being the most severe manifestation 3
• Pain may be pleuritic but can occur at rest without respiratory variation 1, 2
• Risk factors include obesity, immobility, caesarean delivery itself, and hypercoagulable state of pregnancy 3

Acute Coronary Syndrome

• Myocardial ischemia occurs in 7.69% of patients during elective caesarean section, with 42% experiencing peroperative chest pain requiring opioid analgesia 4
• ST-segment changes occur in 42% of patients intraoperatively and 38.5% postoperatively, with significant association between chest pain and abnormal ECG findings 4, 5
• Presentation includes diaphoresis, tachypnea, tachycardia, hypotension, crackles, S3 gallop, or new mitral regurgitation murmur 1, 2
• Obtain ECG within 10 minutes and cardiac troponin levels immediately 6, 2

Acute Aortic Dissection

• Characterized by sudden "ripping" or "tearing" chest pain radiating to the back 1, 6, 2
• Look for pulse differentials between extremities (present in 30% of cases), blood pressure differences >20 mmHg between arms, and connective tissue disorders like Marfan syndrome 1, 6, 2
• Combination of severe pain, abrupt onset, pulse differential, and widened mediastinum on chest x-ray has >80% probability of dissection 1, 2

Peripartum Cardiomyopathy

• Presents with acute heart failure symptoms including dyspnea, chest pain, tachycardia, hypotension, and S3 gallop 1, 2
• Can manifest suddenly during or immediately after caesarean delivery 7

Diagnostic Algorithm

Step 1: Immediate Assessment (Within 10 Minutes)

• Obtain 12-lead ECG within 10 minutes to identify ST-segment elevation, PR depression, or signs of myocardial infarction 6, 2
• Assess vital signs: blood pressure in both arms, heart rate, respiratory rate, oxygen saturation 1, 6
• Perform focused cardiovascular examination for pulse differentials, heart sounds (S3, murmurs), lung sounds (crackles, unilateral absence) 1, 2

Step 2: Laboratory Evaluation (Stat)

• Cardiac troponin I levels immediately, as ischemic levels can be detected even in healthy parturients undergoing caesarean section 4, 2
• Arterial blood gas if hypoxemia or respiratory distress present 3
• D-dimer has limited utility in pregnancy but extremely elevated levels support PE diagnosis 3

Step 3: Risk Stratification

• If hemodynamically unstable (hypotension, shock, cardiac arrest): assume massive PE or acute MI and initiate Advanced Life Support protocols immediately 3
• For massive PE with cardiac arrest, administer thrombolytic therapy (alteplase) during resuscitation, as early aggressive thrombolytic use may be life-saving with good neurological outcomes 3
• Anticipate major bleeding complications including uterine atony requiring hysterectomy when administering thrombolytics peripartum 3

Step 4: Imaging Based on Clinical Suspicion

• Chest x-ray to evaluate for widened mediastinum (aortic dissection), pneumothorax, or pulmonary edema 1, 2
• CT pulmonary angiography for suspected PE (benefits outweigh radiation risks in life-threatening scenarios) 3
• Echocardiography for suspected cardiomyopathy, valvular disease, or right heart strain from PE 7, 3

Management Priorities

For Suspected Massive PE

• Initiate heparin 5,000 IU IV bolus immediately while confirming diagnosis 3
• If cardiac arrest occurs, perform high-quality CPR and administer alteplase during resuscitation 3
• Prepare for emergency hysterectomy if massive hemorrhage develops post-thrombolysis 3

For Suspected ACS

• Aspirin, nitroglycerin (if blood pressure permits), and heparin anticoagulation 2
• Do not use nitroglycerin response as a diagnostic criterion, as esophageal spasm and other non-cardiac conditions also respond 6, 2
• Urgent cardiology consultation for potential cardiac catheterization 2

For Suspected Aortic Dissection

• Immediate blood pressure control (target systolic <120 mmHg) with beta-blockers 1, 2
• Emergency CT angiography or transesophageal echocardiography 2
• Urgent cardiothoracic surgery consultation 7

Critical Pitfalls to Avoid

• Never dismiss cardiac causes in pregnant women, as they frequently present with atypical symptoms including sharp or positional pain 6, 2
• Do not assume a normal examination excludes ACS, as uncomplicated myocardial infarction may have negative physical findings 1, 2
• Do not delay thrombolytic therapy in cardiac arrest with suspected massive PE due to fear of bleeding—maternal survival takes priority 3
• Avoid attributing chest pain solely to anxiety or surgical pain without excluding life-threatening causes first 4, 8, 5
• Do not rely on chest pain characteristics alone; 42% of healthy parturients experience chest pain during caesarean section with ST-segment changes 4, 5

Additional Considerations

Neuraxial Anesthesia-Related Causes

• ST-segment changes and chest pain occur in one-third of healthy parturients under subarachnoid block, with significant association between chest pain and rate-pressure product elevation 5
• These changes may represent demand ischemia from hemodynamic stress rather than true coronary occlusion 4, 5
• However, 7.69% develop true myocardial ischemia with elevated troponin I, requiring differentiation from benign ECG changes 4

Postoperative Monitoring

• Continue hemodynamic monitoring for at least 24 hours postpartum to detect delayed presentations of PE, cardiomyopathy, or fluid shift-related complications 7
• Serial ECGs if initial ECG nondiagnostic but clinical suspicion remains high 2
• Arrhythmia surveillance necessary due to increased postpartum risk 7