Artery splenic

Thrombosis of a splenic artery pseudoaneurysm has been reported in a patient receiving octreotide (24). 

A 55-year-old woman with a history of chronic pancreatitis developed epigastric pain and melena and was found to have a splenic artery pseudoaneurysm expanding a pseudocyst. She was given an intravenous bolus of octreotide followed by an infusion of 50 micrograms/ hour. A CT scan subsequently suggested thrombosis of the pseudoaneurysm, with segmental splenic infarction. Nine months later the pseudoaneurysm had recanalized. 

The octreotide may have contributed by causing vasoconstriction. A case of thrombosis in a splenic artery pseudoaneurysm in a patient receiving somatostatin has previously been reported (25). 

Tang LJ, Zipser S, Kang YS. Temporary spontaneous thrombosis of a splenic artery pseudoaneurysm in chronic pancreatitis during intravenous octreotide administration. J Vase Interv Radiol 2005 16(6) 863-6. 

De Rone T, VanBeers B, de Canniere L, Trigaux JP, Melange M. Thrombosis of splenic artery pseudoaneurysm complicating pancreatitis Gut 1993 34 1271-3. 

This same qualitative difference between adrenaline and noradrenaline obtains for the splenic artery/splenic vein equipressor dosage-response ratios as well, and both observations quite possibly may find their explanation in the recent work of Euler (64-70). He has found that the pressor substance isolated from the heart, blood, liver, and spleen has predominantly the characteristics of noradrenaline. Thus, he has considered Sympathin E to be identical with Z-noradrenaline. 

In some recent comparisons of the pressor responses of adrenaline and noradrenaline, the appreciably longer duration of pressor action of the nor compound was noticed, and this is evidenced in the figures shown by Luduena and co-workers (10) in their recent careful quantitative studies on the relative activities of the two compounds as estimated by various methods on different animals and organs of the body. This longer duration of action of noradrenaline indicates that the over-all inactivation rate in the body is indeed slower. This is in agreement with the indications from the work of West (15) on jugu-lar/portal and splenic artery/vein equipressor ratios that the two compounds are apparently inactivated differently by the liver and spleen. 

Jacobson et al. (1966, 1967) studied gastric secretion in relation to mucosal blood flow by an antipyrine clearance technique in conscious dogs with vagally denervated gastric fundic (Heidenhain) pouches. A vagally denervated fundic pouch is so constructed that the entire arterial blood supply is delivered by the splenic artery. A non-cannulating transducer (electromagnetic flowmeter) and a hydraulic occluder were implanted on the vessel. 

A normal spleen is 11 (10-14) cm in length, 7 (6-8) cm in width and 4 (3-4) cm in depth. The weight of the spleen varies considerably (<100 g to >250 g) a mean value of 150-170 (-180)g can be accepted. The normal diameter of the splenic artery is 4-5 mm, while that of the splenic vein is 8-14 mm with a normal mean value of about 10 mm. With a flow rate of 500-700 ml per minute, the blood flow through the spleen exceeds the arterial blood supply of the liver by a factor of almost 3. The longitudinal axis of the spleen runs parallel to ribs 9-11 from the upper dorsal to the lower ventral. 

Arteriosclerosis affects the extrahepatic liver arteries with the same frequency as the mesenteric arteries, but less frequently than the splenic artery. The intrahepatic branches of the hepatic artery are usually only involved in pronounced arterial hypertension. In these patients, thickening of the media can be found in the small arteries of the portal fields. 

Emboli. Embolic phenomena occur in up to one-third of cases and may result in significant complications. Left-sided endocarditis can result in renal artery emboli causing flank pain with hematuria, splenic artery emboli causing abdominal pain, and cerebral emboli, which may result in hemiplegia or alteration in mental status. Right-sided endocarditis may result in pulmonary emboli, causing pleuritic pain with hemoptysis. 

In splenic trauma, with a life-long increased risk of sepsis after splenectomy, non-operative treatment is the management of choice. In several studies the efficacy of TAE has been shown to be over 90% (Hagiwara et al. 1996). Embolization of the splenic artery, distal to the pancreatic artery, leads to splenic preservation resulting from collateriza-tion by pancreatic and gastric branches. 

Fig. 4.1. CT angiogram showing an independent origin from the abdominal aorta of the common hepatic artery, the left gastric artery, and the splenic artery. This information is useful prior to performing a DSA study...

The dorsal pancreatic artery is the first major pancreatic branch, usually coming off the splenic artery, although many variations have been described (right hepatic artery, SMA, and celiac artery) [15]. After supplying the dorsal surface of the neck of the pancreas, it divides into a left branch, the transverse pancreatic, and into a right branch (branches), which unites with the gastroduodenal or the superior pancreatoduodenal [14]. 

The transverse pancreatic artery is one of the major arteries of the pancreas and generally the major left branch of the dorsal pancreatic. It courses along the inferior surface of the pancreas to unite with the a. pancreatica magna (branch of the splenic artery) [14]. 

Exophytic tumors - Exophytic tumors can be challenging due to their complex vascular supply. Vascular tumors, especially HCC, can parasitize blood flow from many other sources, such as intercostal arteries, renal and adrenal arteries, as well as the splenic artery. A transcatheter CT angiogram can be performed with the catheter in the vessel of interest. Contrast is injected directly into the catheter while CT images of the liver are acquired, giving an extremely accurate view of contrast distribution [8J. If no extra-tumoral blood flow is seen, one can use this vessel to deliver Y microspheres. 

Liu PP, Lee WC, Cheng YF, et al. (2004) Use of splenic artery embolization as an adjunct to nonsurgical management of blunt splenic injury. J Trauma 56 768-772... 

Ishimaru H, Murakami T, Matsuoka Y, et al. (2004) N-butyl 2-cyanoacrylate injection via pancreatic collaterals to occlude splenic artery distal to large splenic aneurysm after proximal coil embolization. AJR Am J Roentgenol 182 213-215... 

Mazer M, Smith CW, Martin VN (1985) Distal splenic artery embolization with a flow-directed balloon catheter. Radiology 1541 245... 

It should also be noted that when larger vessels are occluded with coils, collateral arteries form relatively rapidly and the distal vascular bed is still perfused but at a lower pressure than before the embolization. This is the theory behind the proximal occlusion of the splenic artery to halt splenic hemorrhage. The use of these coils presupposes the existence of collaterals. For example, embolization of the renal artery will most likely not result in viable renal tissue as the kidney is an end-organ and will not have a collateral arterial system that will support the kidney. 

Fig. 3.10a-d. A large splenic artery false aneurysm is demonstrated near tbe bilum of tbe spleen (a). Tbe 6-F RDC catheter is advanced into tbe orifice of the splenic artery and a microcatheter is passed to the site of injury in the distal splenic artery (b). The microcatheter is advanced distally beyond the site of the communication with the false aneurysm. Micronester coils are placed distal and proximal to the origin of the false aneurysm (c and d) and the final angiogram demonstrates occlusion of the lower pole of the spleen with preservation of the upper pole... 

Fig. 5.1. DSA of celiac trunk with a 5-F Cobra catheter. Left gastric artery (white arrow), splenic artery (arrowheads), common hepatic artery (white arrowhead), gastroduodenal artery (small white arrow), right gastroepiploic artery (small white arrowheads), left (small arrow) and right (double small arrow) hepatic artery...

The stomach is irrigated by the gastric arteries (left and right), the gastroepiploic arteries (left and right) and the short gastric arteries (from the distal splenic artery) (Fig. 5.2). 

Fig.7.7a,b. Front and back door embolization of a splenic artery pseudoaneurysm (a) secondary to acute on chronic pancreatitis with a good result (b). This patient is alive and well with no recurrence at 52 months... 

Uflacker R, Diehl JC (1982) Successful embolisation of a bleeding splenic artery pseudoaneurysm secondary to necrotising pancreatitis. Gastrointest Radiol 7 379-382... 

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