Acute mesenteric ischemia

1. Acute Mesenteric
Ischemia
By
Mohammed Saleh Al-dawbali
MD (Egy.), MRCS (Eng.)
Ass. Prof Of Surgery (Sana'a University)

4. Points to be discussed
1. Blood supply to the intestine
2. Causes
3. C/F
4. Investigations
5. Treatment
6. Prognosis

5.  GIT
1. Foregut supplied by celiac artery
2. Midgut supplied by SMA
3. Hindgut supplied by IMA

7. SMA

9. Superior Mesenteric Artery (SMA)
 Largest caliber vessel + 45-degree
angle makes it most commonly
occluded
Celiac Trunk
IMA
SMA
Aorta

10. Superior Mesenteric Artery (SMA)
 Emboli occlude past the middle colic,
causing small bowel ischemia
SMA
Middle Colic
Right Colic
Ileocolic
Jejunal & Ileal
Arteries
Occlusion
Point

11.  Mesenteric Ischemia – ischemia of
the small bowel, usually an acute
cause involving the SMA or SMV.
 Ischemic colitis – ischemia of the
colon, rarely with a known acute
precipitating cause.

12. Acute mesenteric ischemia
 A very serious surgical emergency
that is highly fatal
 Large segment of intestine is
commonly affected , on the other
hand ischemia may be focal and
affect small segment of bowel
 It is usually the superior mesentric a
or v that is occluded

13. Causes
1. Occlusive intestinal ischemia (80%)
A. mesentric artery embolism 45%
B. mesentric artery thrombosis 25%
C. mesentric vein thrombosis 10%
2. Non occlusive intestinal ischemia (15%)
3.Focal small bowel ischemia – rare (5%)
4. Unknown
 ?Mesenteric small vessel disease

15. 1. Occlusive intestinal ischemia
A. mesentric artery embolism 45%
- atrial fibrilation
- mural thrombus after MI
-usu the embolus lodge within few
centimeters of the mouth of the SMA
sparing the middle colic and a few of
the upper jejunal branches

16. B. mesentric artery thrombosis 25%
- The condition complicate cases with
mesentric atherosclorosis
- Pt usu give hx of intestinal angina
- The extent of ischemia is more than
embolus WHY?

17.  Answer
As the block is at the mouth of the SMA
sparing none of its branches

18. C. mesentric vein thrombosis 10%
-it involve the sup. mesentric vein in > 95%
- the condition may be idiopathic or may be
associated with the following disorders
- portal hypertension
- Intra abdominal sepsis
- Hypercoagulable states
- Intake of contaceptive pills

19. 2.Non occlusive intestinal ischemia (15%)
- Called vasospasm ischemia
- Occur more frequently in older pt who are
already
systematically ill on vasopressor drugs
- Low cardiac output states
- Major sepsis
Why ?

20.  Answer
Due to splanchnic vasoconstriction

21. 3. Focal small bowel ischemia - rare
 Partial malrotation, volvulus, mesenteric
hematoma, strangulated hernia
4. Unknown
 ?Mesenteric small vessel disease

22. Pathophysiology
 Damage to the intestine occurs from
the
1. Ischemia
2. Re-establishement of intestinal
perfusion the so called (re-perfusion
injury)

23. Ischemic damage
1. Mucosal layer is the most sensitive to ischemia
sloughs and ulceration and translocation of
bacteria to blood stream septicemia
2. The intestine become gangrenous
Perforation peritonitis
3. The gangrenous part act as an obstruction to
the flow intestinal obstruction

24.  Reperfusion damage
The return of blood flow (spontaneously
Or by surgery) release of oxygen
radicals damage to the cell
membrane

25. Clinical feature
 Sever acute abdominal pain is the main
symptom
- pain respond neither to narcotics nor to
NGT aspiration.
- not proportional to physical signs
 Variable degree of vomiting and bleeding
per rectum why?
 Later with the development of hypovolemia
from blood loss , and pertonitis from
perforation, the pt may become shocked
with abd. Tenderness, rigidity and
distension .

26. Differintial Diagnosis
1. Acute pancreatitis. The distinction is
important WHY?
2. Hernial strangulation.

27. Investigation
 Unfortunately there is no test to
prove the diagnosis.
 The most useful aid is to bear the
condition in mind , particularly in the
atherosclerotic pt or pt with cardiac
arrhythmia.

28.  Blood picture . There is marked leukocytosis
 Serum amylase is elevated in 50% of pt, but is not
as high as in acute pancreatitis
 Plain X ray of the abdomen may show air fluid level
in the proximal intestine . Inetstinal necrosis may
show lately as intramural gas or gas in the portal
venous system
 Plain films – thumb-printing, thickened bowel
(<40% sensitivity)
 CT – thickened/dilated bowel, intramural hematoma,
pneumatosis (64% sensitivity)
 Arteriography is controversial. However the finding
are diagnostic.

29. neumatosis intestinalis is one of the few radiographic findings in patients with m

30. Points to be discussed
 CT angio image of abdominal aorta in the lateral projection
shows narrowing of the celiac trunk (arrowhead) and
occlusion of the proximal SMA (arrow).

31. Treatment
Urgent surgery is the key to survival
Preoperative measures
1. Restoration of blood volume by blood
and crystalloid infusion
2. I.V antibiotics
3. Nasogastric decompression by Ryles
tube

32.  Laparotomy
1.Resection of the gangrenous intestine and
either
- exteriorization of both ends
Or – primary anastomosis and 2nd look after 24h
to check the viability of the intestine
2. Restore the arterial blood flow in case of
reversible ischemia by
- embolectomy
- or by endarteroctomy
- or by bypass

36. 3. In case of mesenteric venous
thrombosis the gangrenous part is
resected and the pt is given post
operative heparin and is discharged
under oral anticoagulant therapy for
at least 3 months to prevent
recurrence

37. Prognosis
 MR = 30% in Venous Thrombosis,
= 45 % in arterial embolism
= 60% in arterial thrombosis
 Embolism has a slightly better prognosis
than arterial thrombosis
 Up to 70% of the small intestine can be
respected without major nutritional
consequences.
 Resection of longer segment develop short
bowel syndrome whose main feature is
malabsorption.

38. II. Chronic intestinal ischemia
 Caused by narrowing of the superior
mesenteric a. and smt the coeliac a
 Etiology
1. atherosclerosis is the main cause
where intima is thickened at the
mouth of the SMA causing narrowing
2. Rarely the coeliac axis is compressed
by median arcute ligament of the
diaphragm

40. C/F
 The main symptom is postprandial pain
which
- start 15-30 minute after a meal
- last for about 1 hour
- this pain is called abdominal angina
. The pt is afraid to eat loss of weight
.an upper abd. Bruit is heard in the majority
of pt
.clinical search is made to find out
atherosclerotic narrowing of other arteries

41. Investigation
 Needed to
1. Exclude other causes of abdominal
pain e.g US and upper GI endoscope
2. Confirm the narrowing of vessels by
aortography which is diagnostic
(esp.lat. view) show the origin of the
arteries as well the presence of
collaterals

42. Treatment
1. Atherosclerosis is surgically treated
either by - endarterectomy (coring
out the thickened intima)
or - by inserting a bypass dacron
graft (from the aorta to the SMA
beyond the narrowing)
2. Division of the median arcute
ligament compression

43. Home massage
Acute Mesenteric Ischemia
 Symptoms are nonspecific
 Dx/tx often delayed
 Timing is everything