Mesenteric & Renal disease Flashcards
What are the branches of celiac artery?
Left gastric, splenic, common hepatic
What is a common variation of celiac trifurcation?
Common hepatic arises from SMA or directly from aorta
What is the first major branch of the SMA?
Inferior pancreatico duodenal artery
What arteries collateralize SMA/Celiac?
SMA > Inferior pancreaticoduodenal > GDA > superior pancreaticoduodenal > celiac

Which level does celiac arise?
L1
Which level does IMA arise?
L3-4
How do SMA and IMA collateralize?
IMA > left colic > inferior marginal artery of drummond
Also: “arc of riolan” - meandering mesenteric artery

What percent of cardiac output does visceral blood flow account for during hypovolemic shock?
10%
What percent of cardiac output does visceral blood flow account at rest?
25%
What percent of cardiac output does visceral blood flow account for after meals?
35%
What type of flow (low resistance vs high resistance, reversal) is in SMA during fasting?
high resistance, low diastolic flow with reversal

What type of flow (low resistance vs high resistance) is in celiac during fasting?
Low resistance regardless of fasting vs post prandial due to low resistance hepatic bed

What type of flow (low resistance vs high resistance, reversal) is in SMA post prandial?
Low resistance in systole and diastole due to vasodilation of splanchnic beds, no flow reversal

What type of flow (low resistance vs high resistance) is in celiac post prandial?
Low resistance regardless of fasting or feeding due to low resistance hepatic bed
In hypovolemic shock, what hormonal pathway causes mesenteric arterial vasoconstriction?
renin angiotensin - direct action of angiotensin 2
Is mesenteric ischemia more common in men or women?
Women, 3:1
What is the most common cause of chronic mesenteric ischemia?
Atherosclerosis
Other than atherosclerosis, what other conditions may cause chronic mesenteric ischemia?
vasculitis/inflammatory disorders - SLE, burgers, radiation arteritis
Median arcuate ligament syndrome
What is the most common cause of acute mesenteric ischemia?
Emboli - 50%
What is the most common cause of non occlusive mesenteric ischemia?
Low flow state - heart failure
What are other causes of non-occlusive mesenteric ischemia?
Afib - decreased LVF, vasoconstrictor drugs, abdo compartment syndrome, aortic insufficiency, low flow states during hemodialysis
What percentage of mesenteric ischemia is caused by mesenteric venous thrombosis?
15%
What are 3 categories of conditions that cause mesenteric thrombosis?
Direct injury - abdo surgery, trauma, IBD, diverticulitis
Stasus: increased abdo pressure, obesity, splanchnic venous congestion
Hypercoagulability: cancer, protein c/s deficiency, AT 3 etc
What is the mortality rate for symptomatic acute mesenteric venous thrombosis?
up to 50%
What is a normal celiac PSV?
< 200 cm/s

What is a normal SMA PSV?
< 275 cm/s

What are the indicatios for revascularizing patients with chronic mesenteric ischemia?
Revascularization is indicated in all patients with symptomatic chronic mesenteric ischemia
What is the optimal I-I angle to view the celiac and SMA?
lateral
What is the optimal I-I angle to view the IMA?
15% RAO
What endovascular treatment is recommended for amenable mesenteric arterial lesions?
SMA stenting
What percentage of patients who undergo mesenteric stenting have distal embolization complications?
8%
What is the most common configuration of open mesenteric bypass?
> 80% antegrade from supraceliac aorta to celiac/SMA with prosthetic graft

What are the overall complication rate following open mesenteric bypass?
20-40%
How successful is mesenteric revascularization for relieving symptoms of chronic mesenteric ischemia
Very successful with open and eno - ~90% experience symptom improvement
What are the benefits for endovascular mesenteric revascularization over open?
Shorter hospital stay, decreased morbidity. No RCTs
What are the benefits of open over endovascular mesenteric revascularization?
Less reintervention, better primary patency (endo up to 60% restenosis)
What is the 5 year survival rate of patients who undergo endo or open mesenteric revascularization?
Nearly identical - 60%
Are males or females more commonly affected by acute mesenteric ischemia?
Females - 3 x more frequent. Usually old women in 60s/70s
What is the typical pattern of bowel viability with SMA emboli?
Proximal jejnum and transverse colon are often spare because SMA emboli tend to lodge just beyond the first few jejunal branches where the SMA tapers (just distal to middle colic artery).

What are the pathologic classifications of acute mesenteric ischemia (from most to least comon)
- Arterial embolism - 50% of cases
- Arterial thrombosis - 30%
- Non occlusive mesenteric ischemia (NOMI) - 20%
Which pathologic classification of acute mesenteric ischemia has the highest mortality rate?
NOMI
Which laboratory investigations are useful for acute mesenteric ischemia?
CBC - hemoconcentration, leukocytosis
Lytes, BUN, Cr - fluid status
ABG - acidosis, high anion gap
Lactate - lactic acidosis
Amylase, AAT, LDH may also be elevated but non specific
Name 3 sensitive CT findings for acute mesenteric ischemia
- Bowel wall thickening
- Mesenteric stranding
- Ascites

Name 4 findings on CT that are 100% specific to acute mesenteric ischemia
- Pneumatosis intestinalis
- SMA or combo Celiac/IMA occlusion
- Arterial embolism
- SMA or portal venous gas

After diagnosing acute mesenteric ischemia - how do you initiate resuscitation?
- Admit to ICU
- Infuse crystalloid fluids
- IV heparin
- IV broad spec antibiotics
- Invasive monitoring - arterial line, CVP, hourly u/ok
Avoid vasopressors - if absolutely necessary then use dopamine or epinephrine and avoid pure alpha adrenergic agents
Name 4 angiographic signs of NOMI (mesenteric vasospasm):
- Narrowing of origins of multiple branches of SMA
- String of sausages (alteranate dilation and narrowing of intestinal branches)
- Spasm of mesenteric arcades
- Impaired filling of intramural vessels.
What type of mesenteric ischemia is this image showing?

NOMI - string of sausages
What type of mesenteric ischemia is this image showing?

NOMI - severe SMA spasm and intramural vessels not seen because of severe ischemia. See improvement after vasodilator administration.

What do you use to treat NOMI?
Most common is phoshodiesterase inhibitor (papaverine) infusion through a catheter in the SMA at 30-60 mg/h
How do you approach SMA if you think you’ll be doing an embolectomy? What about if its a thrombotic occlusion requiring a bypass?
Embolectomy - anterior exposure at base of mesentery - raise up T-colon and make a horizontal incision at the base. Encounter SMV (SMA is to the left of it)
Bypass - lateral exposure above the fourth portion of duodenum similar to an aortic procedure. Usually do a graft from righ iliac to SMA via a lazy “c”

Name 5 ways of assessing if bowel is viable after revascularization for acute mesenteric ischemia
- Visible/palpable pulsation in mesenteric arcade
- Peristalsis
- Colour and appearance of bowel serosa
- Bleeding from cut surfaces.
- Doppler probe.
(Others described - fluoroscein dye, laser doppler, photoplethysmography etc)
*If possible wait 20-30 minutes while you reposition retractors before deciding on bowel viability.
Why would you use IV glucagon in the context of acute mesenteric ischemia?
It increases cardiac output and flow to all layers of the bowel and liver while inhibits GI motility and secretory function. Should be coupled with volume resuscitation to avoid vasodilation-mediated hypotension.
(NB not tested extensively in humans)
What are the more common signs and symptoms of median arcuate ligament syndrome?
- Postprandial abdo pain
- Nausea/vomit
- Weight loss
- Exercise induced pain.

What ultrasound finding is consistent with median arcuate ligament syndrome?
Turbulent flow with elevated PSV on expiration which normalizes or decreases with inspiration and standing erect.
When does the median arcuate ligament compress the celiac artery? On inspiration or expiration?
Expiration
Name 10 conditions associated with mesenteric vein thrombosis
Direct Injury:
- Abdo trauma
- Post surgical
- Peritonitis/abdo abscess
Local Venous Congestion/Stasis:
- CHF
- Obesity
- Abdo compartment syndrome
Thrombophilia
- ATIII deficiency, Protein C&S deficiency, Factor V Ledien
- Malignancy
- OCP
- HITT
What percentage of patients with isolated portal vein thrombosis have intestinal infarction?
0%. PVT is usually asymptomatic unlike mesenteric venous thrombosis with a high transmural infarction rate.
Intra-operatively, how can you tell if intestinal ischemia is due to mesenteric venous thrombosis vs. arterial ischemia (occlusive or non-occlusive)?
1. Extent of bowel involved: MVT limited segments usually jejunum or ileum, arterial is extensive incl jejunum, ileum and colon
2. Colour: MVT - reddish edematous swollen vs. arterial - patchy cyanosis, reddish black discolouration
3. Palpation of SMA and branches: MVT - palpable, arterial - not palpable
4. Bleeding - cut mesentery when bowel removed will have thrombus in MVT but would have pulsatile hemorrhage with arterial

What pathology is shown here? Identify A, B, C,

Mesenteric venous thrombosis
a) extrahepatic portal vein thrombus
b) ascites
c) edematous small bowel loops
What are 2 advantages of UFH over LMWH when initially anticoagulating a patient with mesenteric vein thrombosis?
- Easily reversed if laparotomy required
- More anti-inflammatory effect
How are most patients with mesenteric vein thrombosis treated?
Conservatively with lifelong anticoagulation (warfarin, LMWH or DOAC)
Why does FMD in children seldom have “string of beads” appearance?
Children FMD is typically intimal dysplasia. In adults its most often medial dysplasia with web-like stenoses that give rise to the string of beads appearance.
Name 4 causes of renal artery stenoses
- Atherosclerosis > 90%
- FMD
- Dissection
- Peds - hypoplastic renal arteries, midaortic syndrome, dissection
Name 12 conditions in the differential diagnosis for renovascular HTN
- Essential hypertension
- Glomerulonephritis
- Nephrotic syndrome
- Primary aldosteronism
- Cushing syndrome
- Pheochromocytoma
- Carcinoid
- Hyperthyroidim
- Coarctation of aorta
- Hyperparathoridism
- Sleep apnea
- Volume overload
“TOOK A CRAP”
- T - Thyroid disease
- O- OSA
- O - OCP
- K - kidney disease (proteinuria, elevated cr)
- A - Coarctation of aorta
- C - cushing
- R- renal artery stenosis
- A - Primary aldosteronism
- P - Pheochromocytoma
What are the BP targets for renovascular disease?
Same as for essential HTN - < 140/90. Targets drop to < 130/80 if pt has diabetes or renal insufficiency.
When trying to get exposure of the left renal artery, which branches of the left renal vein may require ligation?
- Adrenal
- Gonadal
- Lumbar

Name 3 RCTs that evaluated endovascular treatment for renal disease
- ASTRAL
- STAR
- CORAL
Name 5 contraindications to endovascular renal treatment.
- Anatomic: terminal portion of main renal artery, short main renal artery, branch arteries beyond the main bifrucation, multiple small renal arteries, lesions in children (hypoplastic renals).
- Open aortic surgery required.
Name 5 causes of renal artery aneurysms
- Atherosclerosis
- FMD
- Trauma/iatrogenic
- Spontaneous dissection
- EDIV
Name 10 causes of acute renal ischemia:
Renal artery thrombosis:
- Atherosclerotic
- Aneurysm
- Dissection
- FMD
Renal artery embolism:
- Afib
- Valvular heart disease
- Cardiac tumour
8. Trauma
9. Iatrogenic
10. Renal vein thrombosis: malignancy/hypercoagulable state

Name 5 arterial beds that provide collateral circulation to the kidney
- Inferior adrenal
- Gonadal
- Ureteral
- Internal iliac
- Lumbar/intercostals

Name 5 laboratory findings associated with acute renal ischemia
- Leukocytosis
- Elevated LDH
- Eosinophilia
- Elevated D Dimer
- Hematuria
NB: Only half of patients with acute renal ischemia have a bump in creatinine, not reliable on its own.
Which developmental disorder is most often seen in patients with abdominal coarctation?
NF-1
