Abdominal aortic aneurysm: Clinical sciences

Chapters:

Watch video only

Introduction0:00–0:29

Abdominal aortic aneurysm, or AAA, is defined as aortic dilatation greater than 3 cm in diameter. Most AAAs are fusiform, which means they’re spindle shaped and involve the entire circumference of the aortic wall.
Based on the symptoms, AAA can be symptomatic or asymptomatic. While most triple As are asymptomatic and found incidentally on imaging studies, all AAAs are at risk for expansion and rupture.
When a patient presents with signs and symptoms suggestive of AAA, you should first perform an ABCDE assessment to determine if the patient is stable or unstable.

Unstable patient0:29–1:52

If the patient is unstable, start with acute management to stabilize their airway, breathing and circulation. This means you might need to intubate the patient, establish IV access, initiate fluid resuscitation, and manage the heart rate and blood pressure before continuing your workup.
Once you have initiated acute management, your next step is to obtain a focused history and physical. The important thing to determine here is whether they have a prior history of AAA.
In an unstable patient with a known AAA, history might reveal sudden onset abdominal, back, or flank pain. Physical examination might show a pulsatile abdominal mass with generalized diffuse tenderness, as well as tachycardia and hypotension.
If this is the case, suspect AAA rupture. Then get a surgical consult for emergent open repair.
However, some patients with complex comorbidities might be poor surgical candidates, so you can consider endovascular repair.
The exact diagnosis of rupture, dissection, or mass effect impinging upon other surrounding blood vessels will be made intraoperatively.Alright, let’s go back to history and physical and talk about unstable patients without known AAA.

Bedside US/Ruptured AAA1:52–2:18

They might also present with a history of sudden onset abdominal, back or flank pain, and have tachycardia, hypotension, as well as a pulsatile abdominal mass on exam.
If so, you should perform a point-of-care ultrasound or POCUS to look for an aneurysm. There are a few things you might see here.First, there might be a AAA with a rupture.

AAA + Rupture2:18–2:48

Now, if the POCUS shows an abnormally dilated abdominal aorta with surrounding free fluid or extravasation of flow on doppler, it’s most likely an AAA with rupture.
Make sure to order stat blood type and call for an emergent surgical consultation for surgical or endovascular repair. Do not delay intervention, as the risk of death by exsanguination is extremely high.Next, you might see AAA with signs of dissection.

AAA + Dissection2:48–3:34

In this case POCUS will show an aneurysm with an aortic wall flap, or a separation of the wall. If you see these findings, you can make a diagnosis of AAA with dissection.
AAAs with isolated abdominal aortic dissections are rare, but they have a high risk of rupture as the separated part of the wall dies from the disrupted blood supply.
Additionally, the dissected wall can impinge upon smaller aortic branches, like the renal or celiac arteries, and cut off the blood supply to vital organs.
It may also affect blood supply to the bilateral lower extremities. Therefore, you must call for an urgent surgical consultation for surgical or endovascular repair.Let’s switch gears and talk about the AAA itself.

AAA only and Other diagnoses3:34–4:16

If the POCUS shows a AAA without any evidence of rupture or dissection, you can diagnose AAA. However, since the patient is hemodynamically unstable, you should remain suspicious for a rupture or dissection that the ultrasound could not detect.
In this case, the patient needs urgent surgical consultation for surgical or endovascular repair, like aortic stent-graft placement to prevent a serious complication, or monitoring by the surgeon.
Finally, if you see a normal abdominal aorta with no evidence of an AAA, consider alternate diagnoses like gastrointestinal bleeding or perforated peptic ulcer disease.Now that we’ve discussed unstable patients, let’s move on and talk about stable patients.

Stable patient4:16–4:56

If you suspect a AAA in a stable patient, your first step is to obtain a history and physical exam. Sometimes, patients will be asymptomatic with a history of AAA.
They usually come in after screening. Be sure to ask about their last screening tests and the size of the AAA during the last 2 screenings to determine how much it has expanded.
If the AAA is greater or equal to 5.5 cm, or has increased more than 1 cm in size over the past year, your next step is to obtain an abdominal CT to measure its current size.

Symptomatic4:56–5:29

On the other hand, some patients might be symptomatic. They typically report a dull abdominal, back or flank pain.
Additionally, the history might reveal some important risk factors for AAA like hypertension or connective tissue disease, smoking history, and family history of aneurysms.
Now, during the physical exam, you might feel a pulsatile abdominal mass. Symptomatic AAAs are concerning because they may indicate a large aneurysm.
These patients also need an abdominal CT to check for a AAA.Alright, now that we ordered imaging, let’s talk about some possible findings.

Ruptured AAA5:29–5:59

Similarly to the unstable patients, you might see a AAA with extravasation of contrast from the aorta, which indicates that the patient has a ruptured AAA.
Even if the patient is hemodynamically stable, all ruptures are surgical emergencies, as they can quickly progress to hemorrhagic shock.
As before, your next step is to call for an emergent surgical evaluation for open or endovascular repair.Let’s move on to our next possible CT finding.

AAA without rupture and AAA not visualized/normal aorta5:59–6:45

If you see dilatation of the abdominal aorta with no evidence of rupture, meaning no extravasation of IV contrast, you can diagnose AAA.
Once you’ve diagnosed AAA, call for a surgical consultation. Remember that symptomatic AAAs have a higher risk of complications, like rupture or impingement of nearby vascular structures, so they may need surgical intervention.
Smaller AAAs under 5.5 cm may require long term monitoring by a vascular surgeon. Finally, if the patient has no history of AAA, and the CT reveals a normal aorta without any evidence of aneurysm, consider alternative diagnoses, like bowel obstruction, myocardial infarction, or gastrointestinal malignancy.Alright, as a quick recap… AAA can present as stable or unstable.

Review6:45–7:30

Unstable patients with a known history AAA have a high risk of rupture, and require emergent surgical or endovascular interventions.
For unstable patients without a known history of AAA, you can perform a quick bedside ultrasound to detect an aneurysm and make a diagnosis.
Any unstable patient with AAA needs an emergent surgical intervention, as life threatening complications can occur at any time.
When it comes to stable patients they should be assessed with an abdominal CT. If you see a AAA with rupture on imaging, call the surgical team for an emergent consultation.
On the other hand, AAAs without rupture should also be evaluated by a surgeon prior to discharge.
Abdominal aortic aneurysm: Video & Qbank | Osmosis