Flashcards in Module 6 CVS continued: Aneurysms Deck (42):
What is an aneurysm?
Localized abnormal dilation of a blood vessel
caused by a congenital or acquired weakness in the media
What is a true aneurysm?
Complete but attenuated (thin) vessel wall
involve all 3 layers of blood vessel
blood remains within the confines of the circulatory system
atherosclerotic, syphilitic, congenital and vascular aneurysm
What are the two types of true aneurysms?
Fusiform: uniform dilation of the entire circumference
Saccular: only a portion of the circumference is dilated
What is a false or pseudoaneurysm?
Extravascular hematoma (Collection of blood outside blood vessels) that communicated with the intravascular space; blood flows outside the circulatory system
Involves only adventitia
wall defect: all 3 layers damaged
The etiology of aneurysms is a weakened media, what are 2 important causes?
1. atherosclerosis: AAA
2. Cystic Medial Necrosis: auto dom disorder; breakdown of collage, elastin, smooth muscle + accumulation of mucopolysaccharide in wall (Cyst like spaces) = weak aortic wall ---- dilation of aortic root w/risk for dissection
What are the only two true aneurysms?
What is the common location for AAA?
Infra renal abdominal aorta
What is the predisposing factor for AAA?
What is the presentation for a AAA?
Asymptomatic or incidental finding on autopsy or physical exam looking for a pulsatile expansile mass
What is the best investigation for a AAA?
Ultrasound or CT
What is the diameter of the aorta at which the AAA will rupture?
over 5 cm
what are the main complications of a AAA?
1.Main complication is rupture ----- hypovalemic shock and sudden back pain (because aorta is retroperitoneal)
2.Renal failure die to compression of ureters by the aneurysm. called mass effect. patient will get hydronephrosis (retrograde flow of urine) which will leads to renal failure. patient will also get pylonephritis due to urinary stasis
3.Thrombus of the lumen leads to stasis and this leads to ischemia of lower extremities and therefore gangrene
What is the common cause of syphilitic aneurysms (Luetic heart disease) = Thoracic aneurysm?
seen in the tertiary stage of syphillis; 15-20 years after initial infection with treponema pallidum bacteria
What is the pathogenesis for thoracic aneurysm?
Starts in vaso vasoroum which supplies the media --- obliterative end arteritis ---- lymphocytes, plasma cells, and mononuclear cells in adventitia --- occlusion of vaso vasorum due to thrombus ---- necrosis of media ---- ischemia causes loss of elastic fibers --- chronic inflammation ---- fibrosis ---- vessel becomes weakened ---- aneurysm
(lymphocytes because its an organism)
What is the mass effect of a thoracic aneurysm?
Mass Effect = compression of central structures
1. Trachea = cough and dyspnea
2. Esophagus = dysphagia
3. Left recurrent laryngeal nerve = hoarseness
What is the best investigation for a thoracic aneurysm?
What is the best investigation for tertiary syphilis?
fluorescent treponemal antibody absorption test
On gross image how do a thoracic aneurysm appear?
Tree-bark appearance or intimal wrinkling ---- due to obliteration of basovisceral and media scarring
remember that structurally intima is not affected just impression intima is making on the media
So both Giant cell arteritis and thoracic aneurysm have tree-bark appearance on gross image, so what is the difference then?
Giant cell ---- inflammation is in the intima and inner media scarring
Thoracic aneurysm---structurally intima is intact and the media is scarring
Other then the already discussed mass effect, what are some other complications of a thoracic aneurysm?
1. Inflammation can spread to aortic roost where coronary arteries originate ---- ischemia of myocardium ---MI
2. Inflammation gets to aortic valve ring ------ regur/incompetence/insufficiency (valve is just leaky now) ---- due to the leakage there is volume overload this leads to ---- cor bovinum (huge heart)---- left ventricular hypertrophy --- left heart failure --- pulmonary edema
patient will have a murmur ---- aortic valve undergoes regur during diastole when valve is closed
3. Stasis in heart causes mural thromboss = arrhythmias + mural thrombosis = embolic stroke
What is the most common cause of death in patients with a thoracic aneurysm?
Left ventricular failure following aortic regur and therefore pulmonary edema and transudate
What is the most common cause for aortic dissection?
Malignant HTN (and this leads to end organ damage)
---not associated with atherosclerosis
What is an aortic dissection?
Entry of blood in between and along the laminar planes of media with extension of blood along the length of the vessel = blood filled channel within aortic wall
Focal loss of elastic and smooth muscle fibers in the media of vessels
what is the pathogenesis for aortic dissection?
intimal tear (from HTN) + defective media (Marfan's syndrome or Ehlers Danlos)
There are two types of aortic dissections, ascending and descending. The more dangerous one is ascending, what two types of ascending aortic aneurysm do you have?
blood can go forward (anterograde) or blood can go back (retrograde)
What is the pathogenesis for anterograde aortic dissection?
Blood goes forward and compromises major vessels
1. Carotid arteries (Stroke)
2.Coronary arteries (MI)
3.Subclavian arteries (reduced blood pressure and pulse so unequal or asymmetric pulse and blood pressure in upper extremities)
4. Anterior Spinal Arteries (myelitis inflammation of the spinal cord next to GI arteries and renal arteries --- can cause renal failure)
What is the pathogenesis for retrograde aortic dissection?
Rupture backward into the pericardial space ----- pericardial tamponade ---- Becks Triad (low BP, distant or muffled heart sounds, distended jugular veins)
Also get aortic valve regur because the blood is gong to the heart
The less dangerous of the aortic dissections is the descending which affects the lower extremities. what is the pathogenesis?
Below the renal arteries so only compromises blow frlow through the iliac, femoral and popliteal
therefore these patients gets gangrene
What is the presentation for a patient with aortic dissection and what do you see on xray?
Severe sudden chest pain that tears to the back
widened mediastinum on xray (Blood collecting in media)
What is the best investigation for an aortic dissection?
What do you see on histology for an aortic dissection?
Blood dissects media into inner 2/3 and outer 1/3
What is a double barrel aorta?
two intimal tears; another intimal tear that lets the blood go back into the true lumen and keeps patient alive
What is the predisposing factor for a Berry Aneurysm?
Congenital defects with the vascular wall
Marfan's syndrome and Ehler Danlos ---- due to cystic medial degeneration/necrosis --- easy for blood to dissect media
ALSO AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE
What is a common location of a berry aneurysm?
between anterior cerebral and anterior communicating
What is the presentation for a berry aneurysm?
What is the presentation once the berry aneurysm ruptures?
During sex or taking a poop likely to rupture
Subarachnoid hemorrhage (presents like meningitis) -- thunder clap headache, photophobia, neck stiffness, fever, seizures due to irritation of meninges
What is the best investigation for a berry aneurysm?
CT scan without contrast (fresh blood so you dont need contrast)
If you see nothing on a CT, what is the next step for a berry aneurysm?
Check for papilloedema if this is okay then do a lumbar puncture to check the CSF
---before 12 hours = RBCs
---after 12 hours = bilirubin (yellow) - xanthochromia
What are some complications of a berry aneurysm?
Ischemic stroke because of cerebral vasospasms
Late complication: communicating hydrocephalus because of fibrosis of arachnoid vili or granulations
What would you see on histology of a berry aneurysm?
Intima is fine but media is defective but still considered a true aneurysm but considered saccular due to outpouching to one side
What is a mycotic (infectious) aneurysm?
Weakening of vessel wall by a microbial infection (salmonella, shigella; Aspergillus- angioinvasive)