Arteriography Evaluation of Splanchnic Artery Occlusive Disease



Arteriography Evaluation of Splanchnic Artery Occlusive Disease



Kyung J. Cho and Manish K. Varma


Splanchnic artery occlusive disease can involve the origin, branches, or distal arteries of the splanchnic arteries, depending on the underlying pathologic process. The newer imaging modalities (including ultrasound, computed tomography [CT], and magnetic resonance angiography [MRA]) provide much of the diagnostic information about splanchnic artery occlusive disease that can be derived from catheter-based angiography. Diagnostic angiography is performed only when necessary information about the splanchnic circulation or small vessel disease cannot be obtained by CT or MRA. It is usually performed before surgical or percutaneous intervention. In patients with acute occlusive or nonocclusive mesenteric ischemia, urgent arteriography should be performed for prompt diagnosis and appropriate treatment.


This chapter reviews the vascular anatomy, equipment, and technique used in catheterization of the visceral arteries and in arteriographic evaluation of splanchnic artery occlusive disease.



Vascular Anatomy


Performance and interpretation of visceral angiographic procedure depend on thorough knowledge of the vascular anatomy. Many variations occur in the branching patterns of the celiac and superior mesenteric arteries as a result of differing degrees of persistence of the dual blood supply from the primitive double aortas. The three major splanchnic arteries supplying the abdominal visceral organs are celiac artery (CA), superior mesenteric artery (SMA), and inferior mesenteric artery (IMA).



Celiac Artery


The celiac trunk, also called the celiac axis, arises from the ventral surface of the aorta below the aortic hiatus of the diaphragm between the T12 and L1 vertebral bodies. It supplies blood to the supper abdominal viscera (including the stomach, duodenum, spleen, pancreas, omentum, liver, diaphragm, and distal esophagus). The first portion of the celiac trunk, the celiac artery descends caudally for 1 to 2 cm and then curves ventrocaudally or ventrocranially (Figure 1A). It gives off the left gastric artery and then divides into the splenic and common hepatic arteries.


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FIGURE 1 Normal vascular anatomy. A, Normal lateral abdominal aortogram (digital subtraction technique). The celiac artery (CA; 8 mm in diameter) arises from the ventral surface of the aorta (A) and courses anteroinferiorly for 1 cm before curving anterosuperiorly. After giving rise to the left gastric artery (arrow), the CA divides into the splenic (SA) and hepatic (HA) arteries. The common hepatic artery becomes the proper hepatic after the origin of the gastroduodenal artery (GDA). The superior mesenteric artery (SMA; 7 mm in diameter) originates from the ventral surface of the aorta 1.2 cm inferior to the lower margin of the CA. It courses ventrally for 3 cm before curving inferiorly. The inferior pancreaticoduodenal artery (arrowhead) arises from the SMA before the middle colic (MC) artery. B, Normal superior mesenteric arteriogram (digital subtraction technique). Right hepatic (RH) artery originates from the SMA. Right colic (RC) artery arises from the ileocolic (IC) artery. The middle colic artery participates in the marginal artery (MA) from which the left colic (LC) branch filled faintly. C, Normal inferior mesenteric arteriogram (cut-film technique). The inferior mesenteric artery (IMA) gives off the left colic (LC), sigmoidal (S), and superior hemorrhoidal (SHA) arteries. The branches of the left colic and sigmoidal arteries participate in the marginal artery (MA) of Drummond. The middle colic (MC) artery is filled from the marginal artery.

The inferior phrenic arteries can arise from the celiac axis proximal to the origin of the left gastric artery. Rarely, the dorsal pancreatic and middle colic arteries arise from the celiac axis as a common trunk and supply the transverse colon.


The splenic artery courses along the cranial aspect of the body and tail of the pancreas. Its branches are the dorsal pancreatic, pancreatica magna, caudal pancreatic, short gastric, and left gastroepiploic arteries. The common hepatic artery courses to the right and anteriorly, gives rise to the gastroduodenal artery, and becomes the proper hepatic artery. It then divides into the right, middle, and left hepatic arteries in the hilus of the liver. Other extrahepatic nonparenchymal branches of the hepatic artery are the right gastric (from the common hepatic), the accessory left gastric (from left hepatic), the falciform (from the middle or left hepatic) and cystic (from right hepatic) arteries.


The gastroduodenal artery supplies the duodenum and pancreas through the posterior and anterior pancreatic arcade arteries and the stomach through the right gastroepiploic artery. The celiac artery communicates with the superior mesenteric artery through the branches of the celiac artery, including the pancreatic arcade arteries of the gastroduodenal artery and dorsal pancreatic artery.


One or more of the branches of the CA can have a replaced origin from the aorta or the SMA. The left gastric artery can arise from the aorta. Rarely the splenic artery has an aberrant origin from the SMA. The left hepatic artery arises from the left gastric artery in about 25% of patients. The right hepatic artery has a completely replaced origin from the SMA in 18% of people and a partially replaced origin in 8%.



Superior Mesenteric Artery


The superior mesenteric artery arises from the ventral surface of the aorta approximately 1 to 2 cm below the origin of the celiac axis at the level of the disc space of the first and second lumbar vertebral bodies (see Figure 1A). Rarely the SMA arises from the celiac axis as a celiacomesenteric trunk or caudal to the origins of the renal arteries. The proximal part of the SMA courses behind the body of the pancreas in close proximity to the uncinate process in a 45- to 60-degree angle to the aorta. This angle may be more severe in patients with chronic mesenteric ischemia, making transfemoral stenting of SMA stenosis difficult. It ranges 8 to 10 mm in width at angiography. It supplies the duodenum, the pancreas, the small intestine, the cecum, and the ascending and transverse parts of the colon.


The branches of the SMA are the inferior pancreaticoduodenal, middle colic, jejunal, ileal, right colic, and ileocolic arteries, respectively (see Figure 1B). The first branch of the SMA usually is the inferior pancreaticoduodenal (IPD) artery, which arises from the SMA or from the proximal jejunal branch. The anterior and posterior branches of the IPD ascend and anastomose with the anterior and posterior branches of the gastroduodenal artery. The jejunal (2–7) and ileal (7–17) branches arise from the left side of the SMA. These arteries form multiple mesenteric arcades, which increase in number distally. The vasa recta from the terminal arcades enter the bowel wall without intercommunication.


The middle colic artery usually arises from the anterior surface of the SMA, distal to the origin of the IPD. The right branch runs along the mesenteric border of the proximal part of the transverse colon and anastomoses with the ascending branches of the right colic and ileocolic arteries. The left branch of the middle colic artery courses along the distal transverse colon and anastomoses with the left colic branch of the IMA.


The right colic artery has various origins. It can arise from the SMA as a common right colic–middle colic trunk or as an ileocolic-right colic trunk. A true right colic artery is present in only 13% of persons. Differentiation of the right colic from the middle colic and ileocolic arteries is difficult because of their anatomic variations and position changes of the bowel.


The ileocolic artery is usually the terminal branch of the SMA and courses to the right side of the abdomen. Its ascending branch anastomoses with the descending branch of the right colic artery. Inferiorly it gives rise to cecal, appendicular, and ileal branches.



Inferior Mesenteric Artery


The IMA arises from the left ventral surface of the abdominal aorta, usually at the level of the third lumbar vertebra. It courses caudally for 3 to 4 cm before giving off the left colic artery (see Figure 1C). The left colic artery gives rise to the marginal artery and one or more sigmoidal arteries. The branches of the left colic and sigmoidal arteries participate in the marginal artery of Drummond in the mesocolon. After giving off the left colic and sigmoidal branches, the IMA terminates as the superior rectal (superior hemorrhoidal) artery, which communicates with the middle rectal artery arising from the left internal iliac artery.



Technique


The percutaneous transfemoral catheterization technique (Seldinger technique) is used most often in the evaluation of splanchnic artery occlusive disease. When the femoral arteries are occluded, the left brachial artery is used. The access site is prepped and draped in a sterile fashion, and the puncture site is anesthetized with either 1% or 2% lidocaine.


A small skin nick using a No. 11 scalpel blade is made in the groin crease over femoral head, and the artery is punctured at a 45- to 60-degree angle to the artery using an 18-, 19-, or 21-gauge needle. The 18-gauge needle is used for a through-and-through puncture; the 19- and 21-gauge needles are appropriate for an anterior wall puncture. The 18- and 19-gauge needles allow insertion of 0.035-inch guidewires, and the 21-gauge needle allows insertion of 0.018-inch guidewires such as Torq-Flex wire guide (Cook Medical, Bloomington, IN).


Over the 0.018-inch wire the 3-Fr–4-Fr coaxial catheter pair is introduced. The inner dilator and wire guide are removed, and a 0.035-inch guidewire is inserted for placement of an introducer (vascular sheath). This technique is the micropuncture access and causes less trauma to the artery and has lower bleeding complication rates. When the 0.018-inch guidewire cannot be passed smoothly after femoral artery puncture using the 21-gauge needle, the inner 3-Fr dilator is inserted over the guidewire, and contrast medium, or preferably carbon dioxide, is injected to evaluate a tortuous or occluded iliac artery or subintimal passage of the guide wire.


Sheath material depends on the size of the catheter and device to be introduced for the splanchnic arterial procedure (diagnostic or interventional). A 4-Fr sheath is used in pediatric patients, a 5- or 6- Fr sheath is used in adults, and a 6- or 7-Fr sheath is used in stent placement to treat chronic mesenteric ischemia caused by celiac or superior mesenteric artery stenosis.


After inserting a sheath in the femoral or brachial artery, the sheath side arm is continuously flushed with heparinized saline at a rate of 30 mL/hour. Another 3000 U of heparin is given if arterial spasm develops at the introduction of a sheath or if severe arterial occlusive disease is present to prevent accumulation of thrombus on the catheter and thrombotic complication at the puncture site.


The angiographic evaluation of splanchnic artery occlusive disease should begin with a lateral aortogram in full inspiration. In patients with suspected median arcuate ligament compression, repeat lateral aortography is performed in full expiration. After the lateral aortogram, an anteroposterior (AP) aortogram is performed. The frame rates for the lateral aortogram should cover the arterial phase at 3 to 4 frames per second. A flush catheter (4–6 Fr pigtail or Omni Flush) should be placed so that the side holes are at the level of the celiac axis. Contrast medium should be injected at 15 to 20 mL/sec for 2 seconds. Carbon dioxide (CO2) may be used as an alternative contrast agent in patients with contrast medium allergy or kidney failure. Because of the buoyancy of the gas, the injection of 15 to 20 mL of CO2 in the supine position will fill the origins of the celiac and superior mesenteric arteries well at the cross-table lateral projection.


The lateral aortogram documents the origins of the CA and SMA, and the AP aortogram visualizes the origin of the renal arteries, aortic bifurcation, and collateral circulation between the SMA and IMA in splanchnic artery occlusion. The origin of the IMA may be difficult to visualize on the standard AP and lateral abdominal aortograms with the injection of contrast medium, but it usually fills well with CO2 in a supine position. The demonstration of collateral circulation from the SMA branches to the IMA branches indicates occlusion of the IMA. If the major splanchnic arteries are occluded, the contrast medium is injected into the aortic bifurcation to visualize collateral circulation to the splanchnic arteries from the the hypogastric arteries.


After the lateral and anteroposterior aortograms, the flush catheter is exchanged over a guide wire for a curved tip catheter (4- or 5-Fr cobra or shepherd’s hook catheter). The catheter is then positioned in the CA and SMA, respectively, and angiography is performed in supine position with injection of contrast medium at a rate of 5 or 6 mL/sec for 5 or 6 seconds at full expiration. These demonstrate splanchnic artery occlusive diseases, including occlusion, stenosis, dissection, aneurysms, neoplasms, and associated collateral circulation. During the venous phase of the superior mesenteric angiogram (approximately 10 seconds after the injection of contrast medium), the superior mesenteric and portal veins are demonstrated. With the injection of contrast medium in the celiac axis, the splenic, coronary, and portal veins can be visualized. In the presence of reversal of portal blood flow in cirrhosis, the portal vein might not be seen during the portal venous phases of celiac and superior mesenteric angiograms.


A reverse-curve catheter is used to catheterize the inferior mesenteric artery. Inferior mesenteric angiography is performed with the injection of contrast medium at a rate of 2 mL/sec for 6 to 8 seconds, and imaging is acquired of the entire rectum, sigmoid colon, and transverse flexure of the colon. In the venous phase the inferior mesenteric vein is seen draining into the splenic or superior mesenteric vein. Blood flow in the inferior mesenteric vein may be reversed in cirrhosis where the inferior mesenteric vein is filled during the portal venous phase of the celiac or superior mesenteric angiograms.


To avoid femoral artery occlusion from femoral artery catheterization in pediatric patients, intravenous digital subtraction arteriography (IV DSA) may be performed to visualize the aorta and the origins of the celiac and superior mesenteric arteries. IV DSA is usually suboptimal in opacifying splanchnic arterial branches because of dilution of the contrast medium, opacification of all the abdominal arteries, and misregistration artifacts from bowel peristalsis. Contrast medium is injected into the superior vena cava (SVC) or right atrium through a 4- or 5-Fr pigtail catheter introduced through an antecubital vein or a jugular vein. Timing of imaging in the abdomen is important because the exposure should be made during the passage of the contrast medium through the abdominal aorta. The exposure delay is 3 to 5 seconds in pediatric patients and 8 to 10 seconds in adult patients. The injection rates for contrast medium is 8 to 12 mL/sec for 2 seconds in pediatric patients and 20 to 25 mL/sec for 2 seconds in adult patients.

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Aug 25, 2016 | Posted by in CARDIOLOGY | Comments Off on Arteriography Evaluation of Splanchnic Artery Occlusive Disease

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