Flashcards in Clinical Aortic Disease Deck (47):
For what do diseases of the aorta account?
significant morbidity (having the disease) and mortality (died from disease).
What happens to the aorta in terms of energy during systole?
It's kinetic energy is converted to potential energy as the aorta is distended.
What happens to the aorta in terms of energy during diastole?
It's potential energy is converted back to kinetic energy as it recoils (due to its elasticity) and pushes the blood into the systemic circulation.
What is important to remember about systolic pressure?
It is a function of blood volume, a function of compliance of the aorta, and resistance of blood flow in the peripheral vasculature.
Are there sensors in the aorta and heart that will regulate systolic pressure?
YES. They send afferent signals through the Vagus nerve to the brain, telling the aorta to distend, the heart to change HR, and the peripheral resistance to change.
Of what does the tunica intima consist?
a single layer of endothelium
Of what does the thick tunica media consist?
a thick smooth muscular wall with lots of elastic fibers and collagen fibers. This provides its strength and elasticity.
Of what does the outermost tunica adventitia consist?
loose connective tissue, some collagen, and the vaso vasorum (blood supply to the aorta).
With what is aortic degeneration associated?
age, men, hypertension, smoking, and hypercholesterolemia.
Do athletes tend to maintain their elasticity and distensibility as they age?
What happens to the collagen/elastin ratio as we age?
It increases :(
What pathological processes can lead to disease of the aorta?
- cystic medial degeneration
- inflammatory disorders
What is cystic medial degeneration?
characterized by smooth muscle cell necrosis, apoptosis, degeneration of elastic fibers within the media, cystic spaces, and extension of the adventitia, thus weakening the wall making it more prone to aneurysm and dissection. All of these occur most importantly in the ascending aorta.
What is a well known syndrome of cystic medial degeneration?
Marfan syndrome: autosomal dominant mutation in fibrillin 1 gene affecting the connective tissue causing dilatation and aneurysm of the aortic root, dilatation of the pulmonary artery, and dilatation or dissection of the descending thoracic or abdominal aorta.
You can also see musculoskeletal and ocular problems.
What is another syndrome of cystic medial degeneration?
Ehlers-Danlos syndrome: multiple genetic inheritance patterns and causes arterial mid-sized rupture of the thoracic or abdominal vessels (frequently abdominal aorta). It is characterized by articular hypermobility, skin extensibility, and tissue fragility.
There are 6 types.
What is Loeys-Dietz syndrome?
another form of cystic medial degeneration. It is inherited autosomal dominantly and is a very tragic form of degeneration causing aggressive aneurysms and dissections occurring distal to the aortic root. Live to 37.
What are some more common cystic medial degenerations?
- familial aortic aneurysm/dissection syndromes
- bicuspid aortic valve (BAV)= most common congenital heart malformation
- autosomal dominant polycystic kidney disease
- Neurofibromatosis= renal arteries
- Turner Syndrome= aortic root and thoracic aorta
How does atherosclerosis affect the aorta?
in the arch, descending thoracic, and abdominal aorta. This will cause complex atheromatous plaques, which can embolize causing resultant stroke or peripheral arterial occlusion.
Cholesterol embolization syndrome may also occur following angioplasty as an embolus travels distally (will see purple toes) but is usually transient and doesn't require heparin since it resolves.
How do inflammatory processes affect the aorta?
They can be systemic or vascular and infectious or non-infectious. Infections can trigger a non-infectious vasculitis by generating immune complexes or by cross reactivity.
What are the common inflammatory disorders that affect the aorta?
Takayasu arteritis, temporal (giant) cell arteritis, polyarteritis nodosa, and Behcet disease.
How can trauma affect the aorta?
can be due to any acceleration/deceleration injury causing traumatic dissection or laceration. Also the trauma can be at level of left subclavian artery causing a sheering affect. Can also form chronic pseudoaneurysm.
What is an aortic dissection?
splitting of aortic wall in the media, forming a false lumen that courses along with the true lumen. An intimal tear starts the dissection, allowing pulsatile high pressure flow into the media.
Could also occur due to rupture of the vaso vasorum and resultant intramural hematoma.
What are the 2 classifications of aortic aneurysms?
1. DeBakey (I, II, III)
2. Stanford (A=proximal/ascending, B=distal/descending)
Can aortic dissection be acute or chronic?
How do we diagnose an aortic dissection?
Good history and physical: 96% of patients will have chest pain described as "tearing or ripping sensation." If acute, it will be more severe at onset and hypertensive on presentation.
If it dissects into the aortic valve plane you can listen for and hear aortic regurgitation.
What can this aortic dissection lead to?
ischemia/infarction, focal neurological defects, malperfusion deficets with pulse discrepancies, or rupture.
What imaging studies can we do for an aortic dissection?
- EKG (don't be fooled if it's dissected into the right or left main coronary artery, which may mimic an infarct pattern).
- ECHO or transthoracic echo (TTE)
- CXR (chest xray)
- CT= good if hemodynamically stable
* Transesophageal echo= portable and good for valves, but difficult for great vessels, ascending aorta, and intramural hematoma.
How do we treat aortic dissections?
- acute type A dissections= surgical emergencies.
- Beta blockade +/- sodium nitroprusside (anti-hypertensive) for both types (but always use beta-blocker before sodium nitroprusside)
- type B dissections= medically unless complications
What is an intramural hematoma?
variant form of an aortic dissection that is a non-communicating blood collection in the aortic wall/media, but no intimal tear. This could occur due to vaso vasorum rupture. This can progress to a dissection via communication with adventita, or can resolve.
What is a penetrating aortic ulcer?
variant form of an aortic dissection that develops when an aortic atheromatous plaque erodes into the aortic media. This can also rupture/dissect or resolve.
What is an aortic aneurysm?
when dilation of aorta is 1.5 times the reference diameter (includes all 3 layers of wall). Complications of these are the leading cause of death in people over 55. 1/3= thoracic, 2/3 = abdominal.
Are aortic aneurysms symptomatic?
What are some different types of aneurysms?
fusiform or saccular aneurysms
Is the size of the aorta different in men and women?
YES smaller in women.
Where are most aneurysms?
- ascending aorta (AV to innominate
- aortic arch
- descending aorta= distal to subclavian
- thoracoabdominal aorta= crawford classification (I-V) for surgeons mostly and their intervention
Can you pick up a thoracic aortic aneurysm using TTE?
How do we treat thoracic aortic aneurysms?
with beta lockers and ACE inhibitors to slow progression
What is the most common symptom in thoracic aortic aneurysms, if symptoms happen to occur?
What rate of change in diameter is reason to be concerned for aortic aneurysm?
> 0.5 - 1cm per year and these are indications for surgery.
What are some surgical interventions?
- Dacron grafts= replace ascending, arch, thoracic and thoracoabdominal aortic segments.
- thoracic endografts
- combined procedures (valve and/or reimplantation of coronary arteries; Bentall)
* What is the MOST common arterial aneurysm?
Abdominal aortic aneurysms!
What are the risk factors for abdominal aortic aneurysm?
smoking, male, age, and hypertension
What are the symptoms for abdominal aortic aneurysm?
pain, sudden onset chest, back, flank pain
Where are most abdominal aortic aneurysms found?
infrarenal (most commonly atherosclerotic)
Why is there more infrarenal aortic aneurysms than any other?
because there is less vaso vasorum here
When does mortality rise in terms of diameter and risk of rupture?
> 5 cm