Vascular Flashcards
Layers of the aortic artery
Aorta = elastic artery
Layers:
- Tunica intima - endothelial cells
- Tunica media - smooth muscle cells, collagen
- Tunica adventitia - CT containing lymphatics, nerves, vasa vasorum (blood vessels that supply blood to the artery)
4 sections of the aorta
- Ascending aorta
- Aortic arch
- Thoracic (descending) aorta
- Abdominal aorta
Terminates at the level of L4 by bifurcating into L and R common iliac arteries
Abdominal aortic aneurysm definition
- Focal dilation (diameter >3cm) of the abdominal aortic artery involving all layers of the wall
Abdominal aortic aneurysm types
Location:
- Suprarenal
- Pararenal
- Infrarenal (most common - 85%)
Size and rupture risk:
- Small (3-3.9cm) - no risk of rupture
- Medium (4-4.9cm) - rupture risk 1%/yr
- Large (5-5.9cm) - rupture risk 5-10%/yr
- Very large (6-6.9cm) - rupture risk 10-20%/yr
- Giant (7-7.9cm) - rupture risk 20-40%/yr
>8cm - rupture risk 30-50%/yr
Risk factors - AAA
- NM: Family hx, older age, sex (m), CT disorder - Ehlers-Danlos syndrome, Marfan syndrome
- M: smoking, HTN, hyperlipidaemia, PVD
AAA - clinical features
Usually asymptomatic <4cm
- Abdominal pain
- Early satiety, nausea/vomiting (caused by compression of adjacent bowel)
- Urinary symptoms of bladder compression
AAA - Features on examination
- Midline pulsatile mass
- Aortic bruit
AAA - Investigations
Bloods:
- D-dimer - elevated
Imaging:
- Abdominal ultrasound
- Abdominal CT
AAA - Management
Conservative management
- Weight loss
- Increase physical activity
- Smoking cessation
Surgical repair
- EVAR - endovascular aortic repair - stent is placed inside the aneurysm via femoral artery cannulation
- Open repair - removes the dilated section of abdominal aorta and replaces it with synthetic graft material
AAA Rupture
AAA rupture
- Caused by a tear in the wall of the dilated abdominal aorta
Types of rupture:
- Contained - perivascular haematoma is sealed off by periaortic structures (pleura, pericardium, retroperitoneal space)
- Free rupture -> massive haematoma
AAA rupture - clinical features
Triad:
- Hypotension, abdominal pain, pulsatile abdominal mass
- Abdominal distension
- Sudden onset of abdominal or flank pain
- Ripping sensation in the back
- Lower extremity pain, coolness, paralysis, paraesthesia
- Syncope
AAA rupture - management
- Immediate surgical stabilisation and repair - EVAR
- Using EVAR - can keep patient awake
- If you tried to put a rupture patient under anaesthesia -> BP would drop too low
Dialysis - definition
A process to filter waste products and remove excess fluid from the blood
Dialysis - indications
Indicated in patients who develop symptoms or signs attributable to kidney failure:
- eGFR <15
- Acid base or electrolyte abnormalities
- Inability to control volume status or BP
- Deterioration in nutritional status unresponsive to dietary intervention
Dialysis - Haemodialysis
- Blood is pumped from the AV fistula into a dialyser
- In the dialyser, waste products filter from the blood through an artificial membrane into a fluid called the dialysate
- Purified blood is pumped from the dialyser into the AV fistula
- The total amount of fluid returned can be adjusted
- Blood is removed distally and put back in proximally
Dialysis - peritoneal dialysis
- In peritoneal dialysis, the peritoneum acts as a filter -> has a large SA and rich network of blood vessels
- A fluid (dialysate) is infused through a catheter inserted through the abdominal wall into the peritoneal space within the abdomen
- The dialysate must be left in the abdomen for a sufficient time to allow waste products from the blood stream to pass slowly into it
- Then the dialysate is drained out, discarded and replaced with fresh dialysate
AV fistula types:
- Ideally in the non-dominant hand
1. Radiocephalic (radial artery, cephalic vein)
2. Brachiocephalic (brachial artery, cephalic vein)
3. Brachiobasilic (brachial artery, basilic vein)
AV Fistula - complications
- Steal - signs of steal - 6 Ps: paraesthesia, pulselessness, pallor, perishingly cold, pain, paralysis
- Stenosis
*Generally occurs at transition points
Signs of stenosis:
- Aneurysm formation
- High pressure on dialysis machine
- Bleeding after dialysis
- Wound - Rupture
- Infection
- Thrombosis
- Occlusions
Assessing fistula function
- Location
- Graft vs. native
- Palpate for thrill
- Auscultate - bruit
- Palpate distal pulses
Assessing fistula function - Red flags
- Pulsatile fistula -> stenosis
- No thrill
- No bruit
- Lack of distal circulation
