Diagnostic Approach

The diagnostic approach for patients presenting with acute aortic aneurysm dissection involves a combination of clinical assessment, imaging studies, and laboratory tests. Prompt and accurate diagnosis is essential to guide appropriate management and prevent potential complications.

1. Clinical Assessment:
   • Obtain a detailed medical history, including symptoms, risk factors, and prior cardiac or vascular conditions.
   • Perform a thorough physical examination, including blood pressure measurements in both arms and assessment for pulse deficits or discrepancies.
     
2. Imaging Studies:
   • Computed Tomography Angiography (CTA):
     • This is the imaging modality of choice for diagnosing acute aortic aneurysm dissection. CTA provides detailed images of the aorta, allowing visualization of the dissection, the location of the entry tear, and the extent of involvement. It can also identify complications such as branch vessel involvement, aortic regurgitation, or pericardial effusion.
     • CTA chest: Sensitivity 83-94%, specificity 87-100%. Gold standard test, defines entire dissection.
   • Magnetic Resonance Angiography (MRA):
     • MRA is an alternative to CTA, especially in patients with contraindications to iodinated contrast media. MRA provides high-resolution images of the aorta and can help evaluate the extent of dissection and involvement of branch vessels.
   • Transthoracic Echocardiography (TTE):
     • TTE is useful for initial evaluation and can provide information about aortic regurgitation, pericardial effusion, and the proximal extent of the dissection. However, its sensitivity for detecting distal dissections is limited.
3. Laboratory Tests:
   • Complete Blood Count (CBC): To assess for anemia, thrombocytosis, or other blood abnormalities.
   • Basic Metabolic Panel (BMP): To evaluate renal function and electrolyte imbalances.
   • Coagulation Profile: To assess coagulation status and exclude any coagulopathies.
   • D-Dimer: Elevated levels of D-dimer can suggest the presence of an acute aortic aneurysm dissection, although it is not specific and false positives can occur.
   • Genetic Testing: In patients with a strong family history or suspected genetic connective tissue disorder, genetic testing may be considered to identify underlying genetic mutations.
4. Differential Diagnosis:
   • Other conditions that can present similarly to acute aortic aneurysm dissection should be considered and excluded. These include acute coronary syndrome, pulmonary embolism, aortic rupture, aortic intramural hematoma, and other causes of acute chest or back pain.

Immediate imaging is required, with CTA chest the gold standard to delineate the dissection. TEE provides rapid evaluation, especially of ascending dissection and complications. Initial management should not wait for confirmatory imaging if suspicion is high.