Mesenteric vascular disease

Mesenteric Vascular Disease
(MVD)
By
Ahmed Abudeif Abdelaal
Assistant Lecturer of Tropical Medicine & Gastroenterology
Sohag Faculty of Medicine
December, 2018

Anatomy of the splanchnic circulation
- The vascular supply to the intestines includes the celiac
artery, the superior mesenteric artery (SMA), and the
mesenteric artery (IMA).
- The celiac axis supplies blood to the stomach, duodenum,
pancreas, and liver.
- The SMA supplies the small bowel from the distal
duodenum to the mid-transverse colon.

- The inferior mesenteric artery supplies the transverse
to the rectum.
- Anastomoses exist between branches of the major vessels
and if one artery is occluded some flow may be
via a patent collateral vessel.
- The superior and inferior pancreaticoduodenal vessels are
collaterals that connect the celiac axis to the SMA.

- The phrenic artery connects the aorta to the celiac axis.
- The marginal artery of Drummond and the arc of Riolan
collaterals that connect the SMA and the IMA.
- The internal iliac arteries provide collaterals to the rectum.

- Griffith point in the splenic flexure and Sudek point in the
rectosigmoid area are watershed areas within the colonic
blood supply and common locations for ischemia.

Classification of mesenteric vascular disease
A) Acute mesenteric ischemia (AMI):
1. Mesenteric artery embolism and thrombosis.
2. Mesenteric vein thrombosis (MVT).
3. Nonooclusive mesenteric ischemia (NOMI).
B) Chronic mesenteric ischemia (CMI).
C) Colonic ischemia.
D) Focal segmental ischemia of the small intestine (FSI).
E) Vasculitis & angiopathy of the splanchnic circulation.

A) Acute mesenteric ischemia (AMI)
- AMI remains a challenging diagnosis with a mortality rate
exceeding 50%.
- The incidence of AMI has increased over the past 20 years
due to longer life expectancies, increased awareness of
ischemic syndromes, and enhanced diagnostic and
therapeutic techniques.

- The various causes of AMI include:
1. SMA embolism (50%).
2. SMA thrombosis (15–20%).
3. Nonocclusive mesenteric ischemia (20–25%).
4. Mesenteric venous thrombosis (5–10%).

A) Mesenteric artery embolism & thrombosis:
- SMA embolism is most frequently due to a dislodged
thrombus originating from the left atrium, left ventricle, or
cardiac valves.
- One third of patients have a history of a prior embolic event
and 20% have synchronous emboli.
- The onset of symptoms is abrupt and dramatic.

- SMA thrombosis usually occurs at the origin of the vessel,
which is frequently an area of severe atherosclerotic
narrowing.
- Acute thrombosis usually occurs in a patient with underlying
chronic intestinal ischemia.

 Clinical picture:
- Patients present with severe, acute, unremitting abdominal
pain strikingly out of proportion to the initial physical
findings.
- On examination the abdomen may be soft and either
nontender or minimally tender.

 Clinical picture:
- Distention is often the first sign.
- Later findings may include signs of peritonitis, especially if
infarction or gangrene has occurred.
- Associated symptoms may include nausea, emesis, and
transient diarrhea.

 Laboratory findings:
- Most patients with early intestinal ischemia do not have
abnormal laboratory findings.
- Leukocytosis with a white blood cell count greater than
15,000/μL is found in 75% of patients.
- Occult blood is found in the stool in 50–75% of cases.

 Laboratory findings:
- Lactic acidosis, hemoconcentration, and raised serum
aminotransferase levels are usually late findings indicative of
intestinal infarction.
- Intestinal fatty acid-binding protein (iFABP) levels,
glutathione S-transferase, D-lactate, D-dimer have shown
promising and some conflicting results in studies.

 Imaging studies:
- CT angiography has 80% sensitivity for AMI.
- Specific findings include thromboembolism in mesenteric
vessels, portal venous gas, bowel wall intramural gas or
pneumatosis, lack of bowel wall enhancement, and signs of
ischemia in other organs.

- MR angiography (MRA) can produce similar images;
however image acquisition takes longer than CT
angiography, which limits its use in the setting of acutely ill
patient.

- Plain films of the abdomen are usually normal, and the
utility of these studies is to exclude other acute abdominal
processes such as perforation or obstruction.

CT angiography with SMA
thrombus 5 cm distal from
the origin of the aorta

CT scan findings
of intestinal
ischemia.
A and B: Small
bowel thickening.
C: Small
intestinal
pneumatosis.
D: Portal venous
gas.

 Angiography:
- It can be both diagnostic and therapeutic.
- It remains the gold standard for evaluation of patients with
suspected AMI with no peritoneal signs.

Angiogram showing
narrowing of superior
mesenteric artery.

 Treatment:
A. Initial management must include:
1. Hemodynamic resuscitation.
2. Correction of precipitating causes of AMI such as arrhythmias,
congestive heart failure, or volume depletion.
3. Aggressive hemodynamic monitoring and support.
4. Correction of fluid and electrolyte abnormalities.

 Treatment:
5. Treatment with broad-spectrum antibiotics.
B. Patients with peritoneal signs or clinical suspicion of
perforation or gangrene require emergent laparotomy, after
hemodynamic stabilization.

 Treatment:
C. Patients who are hemodynamically stable with no
peritoneal signs should undergo angiography to diagnose
obstructive lesions. Once an obstructing lesion is confirmed,
patients can undergo either surgical revascularization or
endovascular revascularization.

B) Mesenteric venous thrombosis (MVT):
- Conditions responsible for the development of MVT can be
identified in over 80% of cases.
- The clinical presentation of MVT can be acute, subacute or
chronic.
- Over 50% of patients with MVT have a personal or family
history of DVT or pulmonary embolism.

Causes of
mesenteric venous
thrombosis

 Clinical Findings:
1) Acute MVT
- Symptoms usually begin a few days to a few weeks (mean, 7
days) before presentation and in 25% of patients have been
present for 30 days before admission.

1) Acute MVT
- Nausea, vomiting, and diarrhea are common, and over 50%
of patients have occult blood in the stool.
- Examination findings include fever (50%), abdominal
distention with mild to moderate tenderness and signs of
dehydration, and hypotension (25%).

1) Acute MVT
- Hematochezia, found in 15% of patients, usually signifies
severe ischemia or bowel infarction.
- Fever, guarding, rebound tenderness, lactic acidosis, and
increased transaminases are late findings that may be
associated with bowel infarction.

2) Subacute MVT
- Abdominal pain can be present for several weeks along with
an unremarkable physical examination.

3) Chronic MVT
- Patients may not have abdominal pain and often present
with stigmata of portal hypertension, varices (esophageal,
gastric, intestinal), and splenomegaly or bleeding from
varices.

- The gold standard for the diagnosis of MVT is CT
angiography.
- Classical findings with a sensitivity of greater than 90%
include a dilated superior mesenteric vein with a clot or
filling defect in the lumen.

- Portal venous gas, air in the small bowel, or free
intraperitoneal air usually indicates intestinal infarction.

 Treatment:
- Depends on presence or absence of intestinal infarction.
- Patients with suspected gut infarction should undergo
laparotomy, to restore mesenteric blood flow and resect
gangrenous bowel segments.

 Treatment:
- By contrast, in patients with no infarction, and with good
mesenteric blood flow demonstrated by angiography,
conservative management can be attempted using
anticoagulation therapy (i.e., heparin).

 Treatment:
- Anticoagulation is usually continued for 6 months or
if coagulation abnormalities preceded MVT.
- Use of thrombolytics such as streptokinase, urokinase, and
tissue plasminogen activator has not been studied in a
group of patients.

 Treatment:
- Catheter-directed thrombolysis has been performed in
some cases.

C) Nonocclusive mesenteric ischemia (NOMI):
- Patients who develop NOMI are typically elderly with
vascular disease, but NOMI can also be seen in patients
vasculitis or who are on vasoconstricting medications.
- Vasopressin and angiotensin are the most likely mediators
of the marked vasoconstriction.

- Predisposing factors:
 Myocardial infarction with decreased cardiac output.
 Congestive heart failure.
 Cardiac arrhythmias.
 Sepsis.
 Dehydration.
 Shock.

- Predisposing factors:
 Medications: diuretics, digoxin, and adrenergic agonists.
 Dialysis.
- Signs and symptoms of NOMI may be similar to those of
AMI.

- The mortality rate from NOMI is high for several reasons,
including advanced patient age, comorbidities, and
in making the diagnosis and reversing ischemia once it has
started.
- Angiography is the gold standard for diagnosis and
management.

- Treatment:
- Hemodynamic resuscitation.
- Antibiotics.
- Intra-arterial infusion of papaverine, a smooth muscle
dilator, which reverses vasoconstriction and restores
mesenteric blood flow.

- Prognosis in patients with AMI:
- Survival of patients with AMI depends on early diagnosis
and treatment.
- Mortality rates from AMI are 70–90% if diagnosis is
and intestinal gangrene develops.
- In patients with angiographically proven AMI who do not
have peritonitis, survival rates now approach 90%.

B) Chronic mesenteric ischemia (CMI)
- CMI is the result of reduced blood flow due to
atherosclerotic narrowing of at least two of three major
vessels (i.e., celiac axis, SMA, or IMA).
- Usually, an adequate collateral circulation has developed
that prevents intestinal infarction. However, acute on
chronic mesenteric ischemia and infarction can develop
suddenly if thrombosis or embolism occurs in a severely
narrowed artery.

 Clinical findings:
- The average duration of symptoms prior to diagnosis is 1
year.
- The classic triad for CMI consists of post-prandial
abdominal pain, weight loss, and an abdominal bruit.
- Pain from abdominal angina is typically recurrent, dull,
crampy, epigastric, and periumbilical, occurring 10–30
minutes after meals and lasting 1–3 hours.

- Because eating consistently triggers pain, food fear causes
patients to eat progressively less, resulting in weight loss
and often cachexia.
- Most patients have a history of peripheral vascular disease
(PVD).

- It is important to note that some patients with PVD
abdominal angina after undergoing surgical repair of
peripheral vascular lesions because of so-called steal
syndrome (i.e., increased blood flow to the extremities and
away from the mesenteric circulation).

- Physical examination of CMI patients usually reveals a soft
abdomen without tenderness during episodes of pain,
hence the classic description of pain disproportionate to
physical findings.
- 50% of CMI patients have an epigastric bruit, especially
post-prandially, and nausea, emesis, and early satiety are
common associated symptoms.

- Angiography is the diagnostic test of choice for CMI;
however, the diagnosis of CMI remains a clinical rather
an anatomic one.
- CT angiography, MRA, and Doppler ultrasound are
noninvasive imaging modalities.
- Angiograms in patients with CMI typically demonstrate
high-grade stenosis in at least two vessels.

- However, it is important to correlate angiographic findings
with symptoms, because some individuals who have
complete occlusion of all three major mesenteric arteries
may remain asymptomatic because of collateral blood

 Treatment:
- Surgical revascularization using aortomesenteric grafting is
the gold standard.
- Endovascular therapy using percutaneous angioplasty with
or without stenting.

C) Colonic ischemia (ischemic colitis)
- It is the most frequent form of mesenteric ischemia,
accounting for 75% of all intestinal ischemia and affecting
primarily the elderly.
- It is estimated that colonic ischemia accounts for 3 in 1000
hospital admissions.
- In many instances no specific cause can be identified.

- In young women, the triad of smoking, use of oral
contraceptives, and carriage of the factor V Leiden
may be associated with increased risk of colonic ischemia.
- Frequent precipitating factors include hypotension,
cardiovascular surgery, dialysis, and dehydration.
- Ischemic colitis is usually a singular event, and only 5% of
patients develop a recurrence.

Risk factors for
colonic ischemia

- Over 90% of patients are older than 60 years.
- Patients usually present with abrupt onset of crampy left
lower quadrant abdominal pain.
- Mild to moderate rectal bleeding or bloody diarrhea within
the first 24 hours. Patients rarely require blood transfusion.

- Physical examination reveals mild to moderate abdominal
tenderness over the affected bowel, most often left-sided.
- Peritoneal signs, if present, would suggest perforation or
peritonitis.

 Diagnostic tests:
- Colonoscopy with biopsies makes the definitive diagnosis;
however, endoscopy should be avoided in patients with
significant abdominal pain or distention because air
insufflation may precipitate perforation in cases of severe
ischemia.

- Endoscopic findings frequently include petechial bleeding,
pale mucosa, and, in more severe cases, hemorrhagic
ulceration.
- CT scans can demonstrate wall thickening, mucosal and
submucosal hemorrhage, and pericolic fat stranding, and
occasionally bowel wall pneumatosis.

Colonoscopic views of
deep ulcerations in a
patient

CT scans
demonstrating findings
in colonic ischemia
A: Colonic thickening
B: Pneumatosis

- Angiography is usually not necessary in the evaluation of
colonic ischemia; however, it should be considered if the
clinical findings raise concern for concomitant small bowel
ischemia or infarction.

- Stool studies should be performed to exclude infections
such as Escherichia coli O157:H7, Campylobacter enteritis,
Klebsiella oxytoca, Shigella, or Clostridium difficile, which
can be associated with hemorrhagic colitis.

 Treatment:
- Bowel rest.
- IV broad-spectrum antibiotics.
- Any medications that can cause vasoconstriction and
promote ischemia should be withdrawn.
- Marked colonic distention is treated with rectal tubes and
nasogastric decompression if necessary.

 Treatment:
- There is no role for anticoagulation or corticosteroids.
- Indications for surgery include peritoneal signs suggesting
perforation, gangrenous colitis, massive bleeding, toxic
megacolon, and recurrent sepsis.

 Prognosis:
- Colonic ischemia is rarely life threatening. However, some
reports suggest that ischemia of the right colon may have
worse prognosis compared with ischemia of other parts of
the colon.
- The natural history of colonic ischemia in the setting of
recent cardiovascular surgery may be more severe.

D) Focal segmental ischemia of the small intestine
- Vascular insults to short segments of small intestine
produce a broad spectrum of clinical features without the
life threatening complications associated with more
extensive ischemia.
- With FSI there is usually adequate collateral circulation to
prevent transmural infarction.

 Causes of focal segmental ischemia (FSI):
 Atheromatous emboli.
 Strangulated hernias.
 Immune complex disorders and vasculitis.
 Blunt abdominal trauma.
 Segmental venous thrombosis.
 Radiation therapy.
 Oral contraceptives.

- FSI can manifest as acute enteritis, chronic enteritis, or a
stricture.
- The most common presentation is chronic small bowel
obstruction from a stricture with intermittent abdominal
pain, distention, and vomiting. Bacterial overgrowth in the
dilated loop proximal to the obstruction can produce a
blind loop syndrome.

- In the acute pattern, abdominal pain often simulates acute
appendicitis. Physical findings are those of an acute
abdomen, and an inflammatory mass may be palpated.
- The chronic enteritis pattern can resemble Crohn’s disease,
disease, with cramping abdominal pain, diarrhea, fever,
weight loss.

 Treatment:
- Resection of the involved bowel.

E) Vasculitis and angiopathy of the splanchnic
circulation
- Inflammation and necrosis can affect splanchnic blood
vessels of all sizes.
- Symptoms depend on the size of the involved vessel and
may be indistinguishable from AMI caused by emboli or
thrombosis.

circulation
- Associated systemic features like renal failure, cutaneous
nodules, and pulmonary infiltrates suggest a systemic
disorder.
- With vasculitis, the ischemic injury typically involves short
segments of the intestine.

circulation
- Abdominal pain, fever, GI bleeding, diarrhea, and intestinal
obstruction are common, as are ulceration and stricture
formation.
- With small-vessel involvement, perforation is less common
than it is with larger-vessel involvement.

circulation
 Causes:
Behçet’s disease.
Buerger’s disease.
Cogan’s syndrome.
Eosinophilic granulomatosis with eosinophilia (Churg-Strauss syndrome).
Fibromuscular dysplasia.
Henoch-Schِ nlein purpura.
Hypersensitivity vasculitis.

circulation
 Causes:
Kawasaki’s disease.
Kِ hlmeier-Degos disease (malignant atrophic papulosis).
Polyarteritis nodosa.
Rheumatoid vasculitis.
Systemic lupus erythematosus.
Takayasu’s disease.

Mesenteric vascular disease

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