Symptoms of Aortic Dissection
If an asymptomatic patient with a suspected AAA experiences dissection, they will most likely develop sudden onset of severe, tearing abdominal or back pain that is maximal in intensity from the very beginning, though importantly, some dissections can remain painless. 1, 2
Cardinal Pain Characteristics
The hallmark symptom of acute aortic dissection is distinctive pain with specific features 1, 2:
- Abrupt or instantaneous onset - the pain reaches maximum intensity immediately, unlike myocardial infarction which builds gradually 1, 2
- Severe intensity from the outset 1
- Quality described as ripping, tearing, stabbing, or sharp 1
- Location varies by dissection site: For abdominal aortic dissection, pain typically presents in the abdomen or back, whereas thoracic dissections cause retrosternal or interscapular pain 2, 3
Critical Physical Examination Findings
High-risk examination features that indicate dissection has occurred 1:
- Pulse deficit - absent or diminished pulses in one or more extremities, found in up to 20% of patients, though this may be transient as the intimal flap position changes 1, 4
- Blood pressure differential >20 mmHg between limbs 1
- New murmur of aortic regurgitation if the dissection extends proximally 1
- Focal neurologic deficits from malperfusion 1
Lower Extremity Malperfusion Symptoms
When abdominal aortic dissection affects leg blood flow, patients develop the "5 P's" of acute limb ischemia 4:
- Pain in the affected limb 4
- Pallor (paleness) compared to the opposite leg 4
- Paresthesia (tingling or numbness) 4
- Paralysis or weakness in severe cases 4
- Poikilothermia (coolness) of the limb 4
Important caveat: Pulse deficits are absent in up to 80% of patients with aortic dissection, so their absence does not rule out the diagnosis 4.
Other Presenting Symptoms
Beyond pain, dissection can manifest with 2, 3:
- Syncope (loss of consciousness) - occurs in up to 20% of patients, sometimes without typical pain 2
- Hypotension from cardiac tamponade or rupture 2
- Oliguria or anuria if renal arteries are involved 2
- Cardiac failure symptoms from acute severe aortic regurgitation 2
The Painless Dissection Pitfall
A critical diagnostic trap: Some dissections present without pain, particularly when associated with atherosclerosis, diabetes, or pre-existing aortic aneurysm 5, 6. In one series of isolated abdominal aortic dissections, 2 of 10 patients (20%) were completely asymptomatic and discovered incidentally 3. This painless presentation can lead to catastrophic delays in diagnosis 7, 6.
Clinical Context for AAA Patients
For patients with known AAA, specific features increase suspicion for dissection 3:
- Abdominal pain was present in 7 of 10 patients with isolated abdominal aortic dissection 3
- Lower extremity ischemia occurred in 1 of 10 patients 3
- Physical examination may show abdominal tenderness (3/10), pulsatile mass (3/10), or be completely benign (5/10) 3
The dissection typically originates at or below the renal arteries in abdominal cases and can extend into the iliac arteries 3.
Time-Critical Nature
The mortality of untreated aortic dissection is catastrophic: 1-2% per hour after symptom onset 1, 8. For ascending dissections managed medically, mortality reaches 20% by 24 hours, 30% by 48 hours, and 50% by one month 1. This underscores why any patient with suspected AAA who develops sudden severe pain or the examination findings described above requires immediate definitive imaging with CT angiography, MRI, or transesophageal echocardiography 2.