Vascular: aneurysms Flashcards
Describe pathophysiology of AAA, RF/protective factors and natural hx they follow.
Aneurysm: irreversible localized dilation in arterial diameter 1.5x that of normal diameter. True aneurysm includes all 3 layers of vessel. False aneurysm is disruption of aortic wall with containment of blood by fibrous capsule.
RF: male, age 75-84 yrs, FamHx AAA, symptomatic atherosclerosis, high cholesterol.
Protective factors: female, diabetes, black.
Complications: rupture, embolization, thrombosis, erosion, fistualize.
Mortality of AAA: 90%. If it ruptures and pt makes it to hospital for Sx, mortality is 50%.
Factors that make an aneurysm more likely to rupture
Size, FamHx of rupture, rate of enlargement, symptomatic AAA (tender abdomen– sign of impending rupture!), comorbidities (diastolic HTN, COPD, dissection, smoking).
Infrarenal vs suprarenal aneurysms
Most common site for aneurysms: infrarenal (originating distal to renal arteries)
Suprarenal: involves one or more visceral arteries but not the chest.
Other sites: popliteal, femoral, thoracic, thoracoabdominal.
Indications for AAA repair
Asymptomatic but >5 - 5.5 cm in transverse diameter (no survival benefit if smaller), symptomatic (tender), if life expectancy for pt is >5 yrs.
(5 cm for women, 5.5 men)
Perform elective repair when size at which risk of rupture (5.5 cm) > risk of mortality from operation (2-5% mortality risk)
Risk of cardiac mortality with AAA repair, assessment steps to mitigate
2-4% cardiac mortality.
Assessment: clinical Hx, ECG, Echo, MIBI, angiography
Pulmonary risks with AAA repair, assessment steps to mitigate
PNA, respiratory failure.
Assessment: clinical hx, CXR, PFT
Renal risks with AAA repair, assessment steps to mitigate
Risk of RF or dialysis.
Assessment: Cr, GFR
Risk of rupture per yr once AAA >8 cm
75%
Important parts of Hx and PEx for asymptomatic AAA
Hx: usually asymptomatic finding on exam, famHx.
PEx: non-tender, pulsatile mass. Examine abdomen with both hands around epigastrum and periumbilical area.
Investigations: CT abdomen.
Screening: abdominal US to check for growth over time. Screen all 1st degree relatives of AAA >50 yrs, all men >65 yrs (esp w/ RF), women >60 yrs.
RF reduction for AAA
Stop smoking, control HTN, DM, hyperlipidemia
Ruptured AAA: important parts of Hx, PEx, initial mgmt
Classic triad: abdo pain, pulsatile mass, hypotension.
Severe back/flank pain, cardiovascular collapse (syncope), deep tenderness.
Rapid diagnosis: US, CT abdo if no known hx AAA.
CXR, ECG, basic labs, cross match.
Initial mgmt: ABCs, volume resuscitation with large IV access and crystalloid infusion. Limite sBP to 100-110 to avoid increased tearing secondary to increased BP. Requires rapid surgery to control bleeding.
DDx for ruptured AAA
Cardiac: ruptured AAA, MI.
Lung: PNA
Abdo: Pancreatitis, perforated peptic ulcer, ischemic bowel, renal colic.
MSK: ruptured intervertebral disk.
Techniques for AAA repair
General: Graft is placed within the lumen of the aorta and vessel walls are closed around it (not resected).
Laparotomy: open abdomen repair. Complication may include an aorto-enteric fistula.
Endovascular repair: catheter run through femoral arteries to aorta then stent is used to place graft. Requires a small space of healthy aorta between renal arteries and AAA for stent to adhere properly. Is less invasive but has high rates of endoleak.
Clinical presentation of popliteal aneurysms and tx
Popliteal = most common site for peripheral aneurysm. Always check popliteal artery one PEx with AAA as 10-15% of patients will have both!
Hx: pulsatile mass behind knee (check bilaterally).
Complications to ask about: distal microemboli, thrombosis/acute ischemia, amputation, rupture.
Investigations: US and angiography.
Tx; Isolation/ligation of aneurysm and bypass of artery.
