1. Splanchnic Artery Evaluation
Lackawanna College
Vascular Technology Program

2. Splanchnic Arteries
Refers to the vessels that supply blood to the bowel
Principally, the celiac axis, superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA)
Stenosis or occlusion can cause acute or chronic bowel ischemia; however, collaterals usually prevent ischemic bowel

3. Three Principal Collateral Paths
The pancreaticoduodenal arcade
Links the celiac artery and SMA via branches around the duodenum and pancreas
The arc of Riolan
The marginal artery of Drummond
Both link the SMA and IMA via mesenteric arterial branches

7. Anatomical Variations

8. Mesenteric Ischemia
Interruption of blood to the small intestine or the right colon
Diagnosis is frequently delayed, increasing mortality
Aging population, mesenteric ischemia encountered more often
Male and female effected equally
Early diagnosis improves outcomes

9. Mesenteric Ischemia
50% are due to SMA occlusion from thrombus or embolus
25% are due to nonocclusive infarct
Remainder are due to IMA occlussion, mesenteric venous thrombosis, or arteritis

10. Causes of Mesenteric Ischemia
Diagnosis must be suspected in older patients with pain or unexplained GI symptoms
The conditions that put the patient at risk:
CHF
Cardiac arrhythmias, particularly a-fib
Recent MI
Atherosclerosis
Hypovolemia
The presence of digoxin may play a role by acting as a splanchnic vasoconstrictor
Patients with history of hypercoagulable state

11. Incidence
Symptomatic patients have obstructive lesions of celiac and SMA 98-99% of the time
One half of those patients also have IMA disease
One third have RAS
One fourth have infrarenal AAA or occlusive disease

12. Frequency, Mortality/Morbidity
AMI is involved in .1% of all hospital admits
Death rates of 70-90% with traditional methods of diagnosis and therapy
More aggressive approach may reduce the mortality rate to 45%
Boley, et al, reported a survival rate of 90% if angio was obtained prior to onset of peritonitis

13. Acute Versus Chronic Acute
Sudden occlusion prior to collateral formation
Needs to be treated immediately
Chronic
Develops over vast time spans
Abdominal bruit
Allows for formation of collaterals
Symptomatic when two of the three mesenteric arteries are effected

14. Clinical History Severe abdominal pain, poorly localized
Sudden onset if embolic, however gradual onset is more common in mesenteric ischemia
Pain is severe and refractory to narcotics
Intestinal angina
Nausea, vomiting and diarrhea may occur in 50% of patients with mesenteric ischemia
Classic triad of SMA embolism: GI emptying, abdominal pain, underlying CAD

15. Collateralization
Because of extensive collateralization, most splanchnic occlusions are asymptomatic
When symptoms do occur, two or three of the splanchnic branches are diseased
Autopsies show hemodynamic stenosis in 6-10% of the population
There are always exceptions

16. Physical Normal abdominal exam in the face of severe abdominal pain
Increased abdominal distension, ileus, peritoniti (noted in advanced ischemia)

17. Normal Physiology

18. Normal Physiology Celiac artery is normally low resistive
Pre- and post-prandial waveforms are similar
Hepatic and Splenic arteries arise from the celiac axis and thus have a low resistive waveform as well
Hepatic artery is hepatopedal
Splenic artery is hepatofugal

19. Celiac Artery Post Prandial

20. SMA Pre-prandial Supplies a changing vascular bed
Preprandial signals exhibit:
Highly pulsatile signals
Are triphasic
And have somewhat of a reversal component below baseline

21. SMA (post prandial) Changes dramatically post prandial
Becomes hyperemic
Should remain above baseline
Exhibit antegrade flow throughout the cardiac cycle

22. Abnormal Physiology

23. Abnormal Physiology
Mesenteric stenosis is difficult to detect below 50 %
When over 50% waveform characteristics begin to change
Velocity increase
Downstream turbulence
Loss of downstream phasicity
Decreased downstream velocities

24. Celiac Artery: Abnormal
Velocities >200cm/s suggest a stenosis > or = 70 %
Downstream HA & SA exhibit decreased pulsatility and increase in acceleration time
In the presence of severe disease the Hepatic artery may be retrograde, and the splenic artery damped

25. Example of Decreased AT

26. SMA Stenosis Velocities > 275 cm/s signifies a stenosis >= 70%
Doppler bruit at stenotic site
Downstream turbulence
Decreased downstream velocity
Broadened waveform
Loss of phasicity downstream

27. SMA Critical Stenosis/Occlusion
Loss of waveforms reverse component
Waveform becomes monophasic and continuous
Velocities will drop
Pulsatility will decrease

28. The Median Arcuate Ligament
Formed by the fibers of the diaphram
Fibers from all origins converge to form a central tendon, which is shaped like a clover leaf
Medial arcuate – over psoas major
Lateral arcuate – over quadratus lumborum
Median arcuate – formed by the union of

29. The Median Arcuate Ligament

30. Median Arcuate Ligament

31. Extrinsic Compression
Median arcuate ligament can extrinsically compress celiac axis
Compression varies with respiration as the ligament slides up and down
Expiration impinges, inspiration releases
Important to differentiate extrinsic compression from atherosclerotic stenosis
The celiac should be interrogated with inspiration and expiration
Most are asymptomatic; psychosocial disorder

32. Splanchnic Aneurysms Not very common Most common, splenic (60%)
Hepatic artery (20%)
Superior mesenteric artery (5.5%)
Celiac artery (4%)

33. Splenic Artery Aneurysm

34. Splenic Artery Aneurysm 3D

35. Splanchnic Aneurysms Ultrasound Appearance
Dilated segment of the vessel
Swirling effect with color flow analysis
Multi-directional, low velocity spectral analysis

36. Mesenteric Ultrasound Examination

37. History & Physical History Post prandial abdominal pain
Onset, and duration of symptoms
Fear of food
Recent weight loss
Risk factors: CAD, Diabetes, Smoker, PVD, CVA/TIA

38. Physical Auscultation
Bruit: strength, duration, changes with respiration
Bowel sounds

39. Scanning Protocol

40. Longitudinal and cross sectional images of proximal, mid, and distal aorta

41. Proximal Celiac Artery (Doppler angle 60 degrees or less)

42. Hepatic Artery (Doppler angle 60 degrees or less)

43. Splenic artery (Doppler angle 60 degrees or less)
This is a bad example

44. SMA (Doppler angle 60 degrees or less)

45. Inferior Mesenteric Artery
Difficult to visualize with ultrasound
Can be a collateral pathway

46. Scanning Considerations
Casual investigation may miss occlusions when normal flow direction is noted
Celiac occlusion, flow may be reversed in the gastroduodenal and common hepatic arteries

47. Diagnostic Criteria

48. Celiac Axis Diagnostic Criteria
Normal Flow
No focal velocity increase
No spectral broadening distal turbulence
Stenosis >= 70%
PSV>200 cm/sec, EDV >=100 cm/sec
Doppler bruit, distal turbulence and spectral broadening
Dampened waveform in the hepatic and splenic arteries
Occlusion of Celiac Axis
No flow detected in the celiac artery
Retrograde flow in the common hepatic artery
Flow in the splenic artery is dampened

49. SMA Diagnostic Criteria
Normal Flow
No focal velocity increase
No spectral broadening or distal turbulence
SMA stenosis <50% is difficult to detect accurately
Stenosis >= 70%
Peak systolic velocity >= 275 cm/sec
End diatolic velocity >= 70 cm/sec
Downstream bruit, turbulence and velocity decrease
Spectral broadening
Impending Occlusion
Total loss of phasicity with low downstream velocity and low pulsatility
Collateral flow detected
Occlusion
No flow noted through the SMA