What are the EKG findings and management of aortic dissection?

ECG Findings in Aortic Dissection

The ECG in aortic dissection is often normal or nonspecific, but when abnormal, it most commonly shows signs of myocardial ischemia including ST-segment elevation or depression—creating a life-threatening diagnostic trap since thrombolytics are absolutely contraindicated and can cause catastrophic hemorrhage. 1

Critical ECG Patterns and Their Implications

ST-Segment Elevation

• ST-segment elevation with typical signs of acute transmural myocardial infarction occurs when the dissection blocks a coronary artery ostium 2
• This ECG pattern is so convincing that thrombolytic therapy may be initiated, which is catastrophic in aortic dissection 2, 1
• The European Heart Journal explicitly states that thrombolytics, antiplatelet agents, and anticoagulation are absolute contraindications when ST-elevation is due to aortic dissection 1

ST-Segment Depression

• ST-segment depression indicates non-transmural infarction or coronary insufficiency 2
• This can result from deteriorating hemodynamics in underlying coronary disease, dissection flaps blocking coronary ostia, or collapse of the true lumen during diastole 2

Normal or Nonspecific Findings

• The ECG may be entirely normal despite ongoing aortic dissection 2
• Previous myocardial infarction changes on ECG should raise suspicion for coronary artery disease versus acute dissection 2

The Diagnostic Dilemma

When chest pain is present, it is impossible to differentiate between myocardial ischemia and aortic dissection by ECG alone—imaging must be obtained before administering thrombolytics 1

Why This Matters for Mortality:

• The ECG findings can be so typical of acute coronary syndrome that they mislead clinicians toward primary PCI or thrombolysis 3
• Administering thrombolytics to a patient with aortic dissection causes hemorrhage into the dissection and is potentially fatal 1
• Bedside transthoracic echocardiography before heading to the cath lab could provide early detection of dissection 3

Immediate Management Algorithm

Step 1: Recognize the Clinical Context

• Severe chest or back pain that is abrupt in onset and at maximum intensity immediately (unlike MI pain which builds gradually) 4
• Pulse deficits in extremities (present in up to 20% of cases, though may be transient) 4
• Hypertension is commonly present 4

Step 2: Do Not Delay Imaging

• If aortic dissection is suspected based on clinical presentation, obtain immediate imaging with CT angiography or transthoracic/transesophageal echocardiography before any reperfusion therapy 5, 6
• In the IRAD registry, CT was the first diagnostic step in 61% of cases, while TTE/TEE was used in 33% 2
• When clinical suspicion is high and complications like aortic regurgitation are present, obtain TTE/TEE even if CT is negative 6

Step 3: Hemodynamic Stabilization (While Imaging is Arranged)

• Control heart rate to 60-80 beats/min with beta-blockers 5
• Target systolic blood pressure of 100-120 mmHg 2, 5
• Beta-blockers should always be used first; add sodium nitroprusside for severe hypertension (starting at 0.25 μg/kg/min) 2
• Modify blood pressure lowering if oliguria or neurological symptoms develop 2

Step 4: Definitive Imaging

• Transoesophageal echocardiography can be performed as the sole diagnostic procedure in hemodynamically unstable patients—call the surgeon immediately 2
• For stable patients, CT angiography is the established gold standard 6
• TEE visualizes the coronary ostia and first 2-3 cm of left coronary and 1-2 cm of right coronary artery 2

Critical Pitfalls to Avoid

• Never administer thrombolytics based on ECG alone when aortic dissection is in the differential diagnosis 1
• Do not assume a normal ECG rules out aortic dissection 2
• Pulse deficits are absent in 80% of patients, so their absence does not exclude dissection 4
• Pericardiocentesis before surgery may be harmful as it reduces intrapericardial pressure and causes recurrent bleeding 2
• Do not waste time obtaining multiple imaging modalities—one high-quality study is sufficient for decision-making 2

When to Proceed Directly to Surgery

• Profound hemodynamic instability requires intubation, ventilation, and TEE as the sole diagnostic procedure with immediate surgical consultation 2
• Echocardiographic finding of cardiac tamponade may lead directly to sternotomy and exploratory surgery without further imaging 2
• Type A dissection (ascending aorta) requires emergency surgery regardless of ECG findings 5