What are the symptoms of an aortic dissection affecting blood flow to a leg?

Symptoms of Aortic Dissection Affecting Blood Flow to a Leg

The primary symptoms of aortic dissection affecting blood flow to a leg include pulse deficits, limb ischemia with pain, pallor, paresthesia, paralysis, and poikilothermia (coolness) of the affected limb. 1

Key Clinical Manifestations

• Pulse deficits in the affected leg are found in up to 20% of patients with acute aortic dissection, though this finding may be transient due to the changing position of the intimal flap 1
• Limb ischemia occurs when the peripheral vessel origin is involved in the dissection or when the true lumen is obliterated by an expanding false lumen 1
• If the iliac bifurcation is completely obstructed, Leriche's syndrome with pulse loss in both legs may occur, which is typically painless 1
• Pain in the affected limb due to acute ischemia 1
• Pallor (paleness) of the affected limb compared to the contralateral side 1
• Paresthesia (abnormal sensations such as tingling or numbness) in the affected limb 1
• Paralysis or weakness of the affected limb in severe cases 1
• Poikilothermia (coolness) of the affected limb compared to the contralateral side 1

Associated Systemic Symptoms

• Severe chest or back pain is typically the initial presenting symptom of aortic dissection, often described as tearing or ripping in nature 2, 3
• The pain is usually abrupt in onset and at maximum intensity from the beginning, unlike myocardial infarction pain which typically builds gradually 2
• Hypertension is commonly present, especially in distal (Type B) dissections 2
• Syncope may occur in up to 20% of patients, even without a history of typical pain 1, 2

Diagnostic Considerations

• Pulse phenomena in the legs may be transient due to the intimal flap's changing position 1
• The symptoms may fluctuate as the dissection progresses or as the position of the intimal flap changes 1
• Bilateral leg symptoms (Leriche's syndrome) indicate complete obstruction of the iliac bifurcation 1
• Malperfusion of the lower extremity is one of the complications that requires immediate intervention in both Type A and Type B dissections 1

Clinical Pitfalls

• Pulse deficits may be absent in up to 80% of patients with aortic dissection, so their absence does not rule out the diagnosis 1
• Symptoms may mimic other conditions such as acute arterial embolism or thrombosis 1
• The clinical presentation can be dynamic and changing as the dissection progresses or the intimal flap position shifts 1
• In some cases, limb ischemia may be the only presenting symptom without the typical chest or back pain 2
• Thrombolytic therapy can be catastrophic if administered to a patient with aortic dissection misdiagnosed as myocardial infarction 2

Management Considerations

• Emergency intervention (surgical or endovascular) is recommended for aortic dissection complicated by lower extremity malperfusion 1
• For Type B dissection with limb ischemia, TEVAR (Thoracic Endovascular Aortic Repair) or other percutaneous malperfusion repair is the preferred approach 1, 4
• If lower extremity malperfusion persists despite initial interventions, extra-anatomic bypass should be considered 1