What are the key components of a physical exam in a patient with suspected aortic dissection?

Key Components of Physical Examination in Suspected Aortic Dissection

The physical examination for suspected aortic dissection should focus on detecting pulse deficits, blood pressure differentials between arms, aortic regurgitation murmurs, and neurological deficits, as these findings significantly increase the likelihood of aortic dissection. 1

Vital Signs Assessment

• Blood pressure measurement in both arms
  • Look for differential >20 mmHg between arms (highly suggestive of dissection) 1, 2
  • False readings may occur if measuring on an arm with compromised arterial flow 2
• Heart rate monitoring
  • Tachycardia may be present due to pain or hemodynamic compromise
  • Bradycardia may indicate vagal response or cardiac tamponade

Cardiovascular Examination

• Pulse examination
  • Systematically check and compare all peripheral pulses (carotid, brachial, radial, femoral, popliteal, dorsalis pedis)
  • Document any pulse deficits or asymmetry (present in up to 20% of patients with proximal dissections) 1
  • Note that pulse deficits may be transient due to changing position of the intimal flap 1
• Cardiac auscultation
  • Listen for diastolic murmur of aortic regurgitation (present in approximately 50% of patients) 1
  • Assess for muffled heart sounds suggesting pericardial effusion/tamponade
  • Check for new murmurs or gallops

Neurological Assessment

• Perform focused neurological examination
  • Assess for altered consciousness or focal neurological deficits (present in up to 40% of proximal dissections) 1
  • Check for signs of spinal cord ischemia (paraparesis, paraplegia)
  • Look for Horner's syndrome (due to compression of superior cervical sympathetic ganglion) 1

Additional Key Findings

• Assess for signs of cardiac tamponade
  • Jugular venous distention
  • Hypotension
  • Pulsus paradoxus
• Check for signs of end-organ ischemia
  • Abdominal tenderness (mesenteric ischemia)
  • Decreased urine output (renal artery involvement)
  • Vocal cord paralysis (compression of recurrent laryngeal nerve) 1
• Inspect for signs of connective tissue disorders
  • Marfanoid habitus
  • Joint hypermobility
  • Skin elasticity abnormalities

Special Examination Techniques

• Bedside transthoracic echocardiography (TTE)
  • While not definitive, can provide valuable information
  • Suprasternal view may visualize ascending aorta and arch 3
  • Can detect pericardial effusion, aortic regurgitation, and sometimes the dissection flap
  • Sensitivity ranges from 59% to 80%, specificity 74% to 100% 1
  • Consider immediate surgical consultation if TTE is suggestive of dissection 1

Pitfalls to Avoid

• Don't delay definitive imaging if aortic dissection is strongly suspected based on physical exam findings
• Don't rely solely on classic findings - less than 50% of patients present with the classic triad of sudden chest pain, pulse deficits, and widened mediastinum 1
• Don't miss associated conditions such as tension pneumothorax which may coexist with aortic dissection 4
• Don't administer thrombolytics without ruling out aortic dissection in patients with ECG changes suggesting myocardial ischemia 2

Remember that physical examination alone is insufficient to rule out aortic dissection, and patients with suspicious findings should undergo immediate advanced imaging with CT angiography, MRI, or transesophageal echocardiography 1.