Dilation or outpouching of the aorta due to the weakened medial layer of the blood vessel. Most commonly caused by hypertension.
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In this lesson we’re going to talk about Aortic Aneurysms. This is something you will see in the clinical setting either because a patient will have a history of one or they’ll present in an emergent situation because of it.
So an aortic aneurysm is a dilation or outpouching of the aorta due to a weakened medial layer of the vessel wall. When the medial muscle layer gets weakened, any kind of high pressure can cause it to balloon out. What artery in the body is under more pressure than the one the heart pumps directly into, right!? The aorta has a tremendous volume of blood flowing through it under tremendously high pressures compared to the other arteries in the body. So imagine adding hypertension to that scenario. A weak medial layer plus higher pressures means more dilation and even weaker walls of the vessel. In the aorta they’re classified by location, you have a thoracic aortic aneurysm or TAA which typically happens above the diaphragm, and an abdominal aortic aneurysm, most commonly known as a “Triple A”, which occurs in the abdominal aorta. As you can imagine, the highest pressures are gonna be right up here in the aortic arch where the heart pumps directly into it, so this is a common place for thoracic aneurysms.
Now, there’s four different types of aneurysms based on their shape. First is the fusiform – this means it involves the entire circumference of the vessel, just like the ones we saw on the last slide. The second type is called Saccular and it is when the aneurysm comes off just one side of the vessel. Now with both of these, The problem comes when blood flows through these at high pressure. It starts to whip around here in the outpouching, causing a lot of turbulence and higher pressures. Lots of pressure, lots of turbulence. We’ll talk in a second about how you can actually feel and hear this turbulence in the aorta! The third type of aneurysm is a little different, it’s called a Dissecting Aneurysm. What happens is that the pressure is so high it actually tears away the inner lining of the vessel and blood begins to pour into the space between the layers, this puts pressure on the medial and outer layers, and creates this ‘false lumen’ over here. So now what we see is that much less blood is actually getting past this point, because it’s all leaking out into this space here. These patients tend to have more severe symptoms. This blood here will continue to put pressure on the outer walls – putting it at higher risk for rupture. Lastly, there’s something called a False aneurysm – basically they will see what looks like an aneurysm on a scan, but turns out it’s actually a blood clot that has formed around the outside – so the inner lumen and flow of blood isn’t actually compromised. So…can you already see some of the issues the patients might have? Perfusion problems, maybe some pain because of the pressure on the weak walls, and of course the risk for rupture.
Now, smaller aneurysms may not actually be symptomatic, but you’ll still be able to see them on a CT or ultrasound. The larger the aneurysm, the more symptomatic the patient will be and the higher the risk for rupture. So, what’s the difference in presentation between a thoracic aneurysm and an abdominal one? So, this is our heart and here’s the aorta coming off of it. Then, midway down we’ve got the renal arteries going to the kidneys, then the abdominal aorta continues down. So if we have a thoracic aneurysm here – you’ll see this pain in their chest that radiates to their back, shoulders, and abdomen. And depending on the size, it can also increase pressures in the thoracic cavity and cause some dyspnea or trouble breathing. For abdominal aortic aneurysms or Triple A’s you can actually see and feel a pulsation in the abdomen when the patient is lying flat. You can also hear a bruit when you listen to the abdomen. A bruit is the sound made by that turbulent blood flow we talked about – it’s a swooshing of blood in that aneurysm. They’ll also have pain on palpation and may even have a hematoma on their flank – especially if it’s leaking or has ruptured. Notice here that it’s imperative to do a thorough abdominal assessment – inspection, auscultation, palpation, etc. Then of course, like we mentioned before – with any aneurysm there’s a possibility of signs of decreased perfusion distal to the aneurysm, depending on the size and severity.
The most severe risk with an aneurysm is that that weakened blood vessel wall can rupture. Remember this aorta is under super high pressure and has a tremendous volume of blood. If this thing ruptures, the patient is going to be in BIG trouble and could bleed out very quickly so they need to go to the OR immediately. Signs of a rupture would be severe, sudden onset of pain which radiates to the back, flank, or even the groin. And of course because blood flow is so compromised, the patient will have signs of shock – you will learn more about shock in the coming lessons, but essentially shock is a state where the vital organs aren’t getting oxygenated blood flow. Your cardiac output drops, blood pressure drops, you’ll probably see the heart rate go up to compensate, and of course you’ll see signs of poor perfusion – cool, clammy skin, weakness, confusion, diaphoretic, decreased pulses, etc.
So the number one thing we can do for a patient with an aneurysm is manage their blood pressure. The goal is to decrease the pressure put on that weak vessel, while still maintaining a MAP that’s sufficient to perfuse the rest of the body, usually > 65 mmHg. Of course we’ll use things like beta blockers, ACE inhibitors, etc. The only way to fix an aneurysm is surgically – they can open the patients chest or abdomen to directly repair the aneurysm by resecting or removing the weak portion of the vessel. Or, they can do what’s called an Endovascular Aneurysm Repair or EVAR. Essentially they thread a catheter up through the femoral arteries and deploy a stent graft. The goal here is that the blood would flow through the graft and bypass the weak part – that way it doesn’t worsen or rupture. After either of these procedures we need to make sure we’re assessing distal pulses as well as vital signs and hemodynamics. We also need to monitor renal function – it’s super important that we make sure the kidneys are being perfused. So we’d monitor Urine output, BUN, Creatinine, etc. Then we need to monitor their incision site to prevent infection or other complications. Usually we have the patient splint with a pillow if they have to cough, or deep breathe – that protects them from dehiscence or evisceration, it’s also less painful.
As with the other lessons, there is a care plan so you can see detailed nursing interventions – but here are the top nursing concepts for Aortic Aneurysm – Perfusion, Perfusion, Perfusion. No, seriously. This is a massive perfusion issue and that has to be your top priority. Yes, they may have some pain, so you could consider comfort. They also may have clots or bleeding, so you could consider clotting – but I REALLY want you to think perfusion, perfusion, perfusion – check the abdomen for pulsating masses, check all the peripheral pulses, watch your hemodynamics – this is your TOP priority for this patient.
So let’s recap – an aortic aneurysm is a dilation or outpouching of the aorta due to a weakened medial layer. That weakened vessel is under high pressure – that creates turbulence in the vessel and puts them at high risk for rupture. Classic symptoms are pain radiating to their back, you’ll be able to see, hear, and feel the aorta pulsating in the abdomen, and you’ll see signs of shock – especially if it ruptures. We prioritize controlling their blood pressure and can surgically repair if necessary to prevent rupture. Then remember – your priorities are perfusion, perfusion, perfusion!!
So that’s aortic aneurysms – when you see this patient in the clinical setting, we hope you remember this lesson and feel super confident taking care of them! Go out and be your best selves today! And, as always, happy nursing!