Emergency Med 3: AAA and Aortic Dissection Flashcards
Why are Abdominal Aortic Aneurysms so dangerous ?
Most are asymptomatic until rupture. A majority of patients who rupture will not make it to the hospital
Which demographics pose the greatest risk of AAA ?
Elderly
Males
Is AAA familial ?
Yes !
80% of patients with AAA have a first-degree relative with a history of aneurysm
What are risk factors involved with AAA ?
other aneurysms, hypertension, peripheral arterial disease, smoking, diabetes, and collagen vascular disease
Hallmark of aneurysm pathogenesis ?
Destruction of the medial layer of aorta
What molecules are drastically reduced in an aneurysmal aorta ?
Elastin and collagen
What happens to elastic fibers in a normal aorta going from proximal to distal ?
Elastin decreases –> more occurences of AAA distal to the renal arteries.
What diameter of AA is used as diagnostic for AAA ?
3 cm or more
How is LaPlaces Law applied in determining risk for AAA rupture ?
Wall tension = (pressure X radius)/tensile force
Thus the more dilated the AA gets the more tension will be on the wall and thus the greater chance of rupture occurring
Larger aneurysm will expand more quickly
What symptom occurs most often in patients with AAA ?
Abdominal pain (77%)
List symptoms often associated with AAA
Abdominal pain (77%) Flank or back pain (60%) Vomiting (25%) Syncope (18%) Hematemesis (5%) Aneurysm has fistulized into the GI system
Classic History for AAA rupture
syncope without warning symptoms followed by severe abdominal/back pain or abdominal pain, hypotension, and a pulsatile abdominal mass
What is a common misdiagnosis for AAA and why ?
Kidney stones
Pain is often localized to unilateral flank.
(May also be seen in costovertebral angle, or in a single quadrant of the abdomen)
N/V are also commonly seen.
Hip pain, tenesmus, and urinary bladder symptoms have also been described in AAA. What is tenesumus ?
Feeling of needing to constantly defecate
On physical examination, what percentage of patients with AAA show a pulsatile mass ?
70 %
Other Clinical Features include :
Abdominal tenderness (41%)
Pain, Mass, Hypotension (30-40%)
Abdominal bruit (5-10%)
Absent lower extremity pulses (6%)
What does tenderness to palpation often indicate ?
rupture (however, non-tenderness does not indicate lack of tear.
periumbilical ecchymosis (Cullen’s sign) or flank ecchymosis (Grey-Turner’s sign) are indicative of ?
AAA rupture
How does GI bleeding occur in AAA rupture ?
Usually due to fistula to duodenum –> massive bleeding
At what size are AAA considered to be at significant risk of rupture ?
> 5cm
Common differential/misdiagnosis
Renal colic Pancreatitis Intestinal ischemia Diverticulitis Cholecystitis Appendicitis Perforated viscus Bowel obstruction Musculoskeletal back pain Acute MI
What are radiologic studies used for with suspected AAA ?
Confiramation (should not delay treatment however)
CT Scanning for AAA
Identifies 100% of AAA and > 95% of rupture
Can demonstrate the anatomic details of the aneurysm
Should only be used in stable patients
Can make alternative diagnoses