CHAPTER 12 Hepatic, splenic, and portal vascular systems
Techniques for celiac and superior mesenteric arteriography are described in Chapter 11. Splenic or common hepatic arteriography is performed with a variety of catheters, including cobra and sidewinder shapes. Steerable, hydrophilic guidewires simplify catheter placement. Alternatively, high-flow coaxial microcatheters are used to select the main splenic or hepatic arteries and their branches.
The hepatic veins are studied from an internal jugular (IJ) vein approach using a multipurpose angiographic or cobra-shaped catheter. In a small percentage of patients, a femoral route is necessary because of the downgoing orientation of the main hepatic vein entering the inferior vena cava (IVC). This situation may occur after some liver transplantations or with hepatic vein anomalies (see later discussion). Wedged hepatic vein manometry and venography are done with a balloon occlusion catheter inflated within a peripheral hepatic vein branch or a 5-French (Fr) endhole catheter advanced into a peripheral vein until resistance is met. A flat pressure waveform indicates a wedged position. Measurements should be obtained before contrast injection, which may spuriously elevate the sinusoidal pressure. Overinjection can produce subcapsular extravasation and liver perforation. Retrograde filling of the portal vein is enhanced when CO2 is used as the contrast agent (30 to 60 cc of gas injected rapidly).
The splenic, superior mesenteric, and portal veins are visualized on the late phases of celiac or superior mesenteric arteriography (“indirect portography”). Direct splenoportography is rarely required in the evaluation of patients with portal hypertension.1 Iodinated contrast or CO2 (15 to 20 cc) is injected through a micropuncture catheter inserted into the substance of the spleen with ultrasound guidance. The tract is embolized with Gelfoam as the catheter is withdrawn.2,3
The liver bud develops between the pericardial cavity and the stalk of the primitive yolk sac.4 Liver cords insinuate between tributaries of the vitelline and umbilical veins to form the hepatic sinusoids. Branches of the right vitelline veins around the duodenum develop into the central portal veins.5 The right umbilical vein involutes, and the left umbilical vein becomes the primary inflow vessel to the liver. The hepatic venous outflow is directed toward the upper portion of the right vitelline vein, which ultimately forms the hepatic veins and the intrahepatic portion of the IVC. The ductus venosus connects the left umbilical vein (portal venous inflow) to the right vitelline vein (hepatic outflow). Shortly after birth, the ductus venosus and left umbilical vein close and form the ligamentum venosum and ligamentum teres, respectively.
With the advent of living-related split-liver donor transplants, more ambitious surgical techniques for segmental hepatic resection, and transcatheter methods for treatment of liver tumors, a detailed understanding of the normal, variant, and collateral hepatic circulations is critical for the vascular interventionalist. For preoperative planning, high-quality computed tomography (CT) or magnetic resonance (MR) arteriography and venography are both extremely accurate.6–9 For transarterial therapy, selective digital angiography is required, including celiac and superior mesenteric arteriography, right and left hepatic arteriography, and often more subselective catheterization.10,11
The liver is divided into right and left lobes separated by the major fissure. The right lobe has anterior and posterior segments; the left lobe has medial and lateral segments. The caudate lobe is anatomically distinct from the right and left lobes. By convention, segmental anatomy is based on the original system of Couinaud demarcated by the three main hepatic veins and a transverse plane at the level of the portal vein bifurcation12,13 (Fig. 12-1). However, the relationship between these landmarks identified on cross-sectional imaging and the true anatomic segmental anatomy is only approximate.
Figure 12-1 Segmental anatomy of the liver. A, Schematic drawing shows segmental divisions along with portal vein inflow and hepatic vein outflow. Segment I (caudate lobe) lies posterior to segments III and IV and in front of the inferior vena cava. Computed tomography scans through the upper (B) and lower (C) aspects of the liver, with segments noted.
(A,Adapted with permission from the website of the American Hepato-Pancreato-Biliary Association, www.ahpba.org.)
The liver is supplied by the common hepatic artery and portal vein. Normally, about three fourths of the blood supply to the liver comes from the portal vein. Any reduction in hepatic arterial or portal venous blood flow leads to a compensatory increase in flow through the companion system. The biliary tree is nourished by branches of the hepatic arteries.
The common hepatic artery arises from the celiac artery (Fig. 12-2). After giving off the gastroduodenal artery, it becomes the proper hepatic artery. This vessel enters the porta hepatis and divides into the right hepatic artery (RHA) and left hepatic artery (LHA), which feed their respective lobes. The RHA supplies segments V to VIII (and sometimes segment I, caudate lobe). The LHA supplies segments II, III, IVa, and IVb. The inconsistent middle hepatic artery, which, if present, supplies segments IVa and IVb, usually originates from the right hepatic artery or forms a true trifurcation. Variations in hepatic arterial anatomy are common (see later discussion). Although the hepatic arteries are considered end arteries, intrahepatic and extrahepatic anastomoses do exist. The origins of important branches are outlined in Table 12-1.
Figure 12-2 Normal hepatic arterial anatomy. A, Celiac arteriography shows right (R), middle (M), and left (L) hepatic arteries. Normal left (B) and right (C) hepatic arteriograms in another patient. IV indicates the branch to segment IV.
|Vessel||Typical and Atypical Origins|
|Right gastric artery|
|Supraduodenal artery||GDA, CHA, LHA, RHA, cystic|
|Dorsal pancreatic artery|
|Falciform artery||MHA, LHA|
CHA, common hepatic artery; GDA, gastroduodenal artery; LGA, left gastric artery; LHA, left hepatic artery; MHA, middle hepatic artery; PHA, proper hepatic artery; RHA, right hepatic artery; SA, splenic artery; SMA, superior mesenteric artery.
The portal vein (PV) is formed by the confluence of the superior mesenteric vein (SMV) and splenic vein14 (Fig. 12-3). It is valveless. Normal main portal vein pressure is about 3 to 5 mm Hg. The SMV has numerous jejunal, ileal, and colonic tributaries. The inferior mesenteric vein (IMV) joins the splenic vein or the SMV.15 The right gastroepiploic, pancreaticoduodenal, and right colonic veins often merge into a common gastrocolic trunk that drains into the right side of the SMV near its junction with the PV. The right and left gastric (coronary) veins join the superior surface of the main portal or central splenic vein. Multiple coronary veins often exist.
(A,From Lundell C, Kadir S. The portal venous system and hepatic vein. In: Kadir S, editor. Atlas of normal and variant angiographic anatomy. Philadelphia: WB Saunders; 1991, p. 370.)
The portal vein runs anterior to the IVC and posterior to the head of the pancreas before entering the liver. The PV bifurcation is outside the liver capsule in about half of the population.16 The right and left PVs and their branches follow the hepatic artery into the liver. The left PV supplies segments I to IV.17 The right anterior PV supplies segments V and VIII; the right posterior PV supplies segments VI and VII. The caudate lobe is usually fed by branches of the left PV. The remnant of the umbilical vein (ligamentum teres) is connected to the left PV. A patent paraumbilical vein arising from the left PV is sometimes seen in patients with portal hypertension.
The liver is drained by the hepatic veins. The right and left hepatic veins run between the segments of the right and left lobes of the liver, and the middle hepatic vein lies in the main lobar fissure (Fig. 12-4). These vessels converge into the IVC within several centimeters of the diaphragm. The right hepatic vein (draining segments VI and VII) joins the right posterolateral surface of the IVC. The middle hepatic vein (draining segments V and VIII) and left hepatic vein (draining segments II and III) confluence enters the anteromedial surface of the IVC. Segments IVa and IVb are drained by the left or middle hepatic vein. The caudate lobe empties independently into the intrahepatic IVC.
The liver parenchyma is composed of hepatic lobules, which contain the hepatocytes and sinusoidal spaces that form the functional units of the liver18 (Fig. 12-5). Neighboring lobules are organized into acini. Hepatic arterial, portal venous, and biliary duct branches follow the borders of the lobules. Hepatic arterioles feed the sinusoids directly and through communications with portal venules that perforate the lobules. Normally, blood flows freely between acini. Central veins at the core of each lobule drain the sinusoids. These venules coalesce into the hepatic veins.
The splenic artery supplies the spleen and portions of the pancreas and stomach19 (Fig. 12-6). It follows the superior edge of the pancreas along with the splenic vein. With advancing age, the splenic artery can become extremely tortuous. Near the splenic hilum, the artery usually divides into superior and inferior branches. Superior and inferior polar arteries often arise from the midsplenic artery and supply their respective splenic segments. The left gastroepiploic artery originates from the distal inferior polar artery and then courses along the greater curvature of the stomach. Numerous short gastric branches feed the fundus of the stomach. The splenic artery also has numerous branches to the body and tail of the pancreas. The largest of these vessels are the dorsal pancreatic artery (which may originate on the celiac trunk) and the pancreatica magna artery (see Fig. 12-6).
Figure 12-6 A, Normal splenic arteriogram showing the dorsal pancreatic (D), transverse pancreatic (T), pancreatica magna (M), and omental (O) branches. Proxaimal irregularity is guidewire-related spasm. B, Late-phase indirect splenoportogram. Diminished density in the main portal vein (arrow) is caused by unopacified inflow from the superior mesenteric vein.
The splenic vein lies behind the upper border of the pancreas below the splenic artery (see Fig. 12-6B). Its tributaries include the short gastric, left gastroepiploic, pancreatic, and inferior mesenteric veins (see Fig. 12-3).
Anomalies of hepatic artery origin and number are common10,20–23 (Table 12-2). The most frequent variants are accessory and replaced hepatic arteries, such as the right hepatic from the superior mesenteric artery (SMA), the left hepatic from the left gastric, and the common hepatic from the SMA (Fig. 12-7; see also Figs. 11-7 through 11-9). Accessory hepatic arteries are those in which a portion of the affected lobe is supplied by a vessel with an aberrant origin. Replaced hepatic arteries are those in which the entire lobe is supplied by a vessel with an aberrant origin. Accessory hepatic arteries supply isolated hepatic segments and are believed by most authorities not to be redundant arteries.24
|Type||Michels (%)||Recent Series (%)|
|I: Classic Anatomy||55||58-79|
|II: Replaced LHA||10||3-12|
|III: Replaced RHA||11||6-15|
|IV: Replaced RHA and LHA||1||1-2|
|V: Accessory LHA from LGA||8||3-11|
|VI: Accessory RHA from SMA||7||3-12|
|VII: Accessory RHA and LHA||1||0-1|
|VIII: Accessory RHA/LHA replaced LHA or RHA||2||1-3|
|IX: Replaced CHA to SMA||4.5||1-2|
|X: Replaced CHA to LGA||0.5||0|
|Double hepatic artery||1-4|
|Triple hepatic artery||0-7|
|Separate CHA origin from aorta||0.4-2|
|Replaced PHA to SMA, GDA origin from aorta||0.3|
CHA, common hepatic artery; GDA, gastroduodenal artery; LGA, left gastric artery; LHA, left hepatic artery; PHA, proper hepatic artery; RHA, right hepatic artery; SMA, superior mesenteric artery.
Figure 12-7 Variant hepatic arterial anatomy. A, Left hepatic artery (black arrow) replaced to the left gastric artery. B and C, Right hepatic artery (white arrow) replaced to the superior mesenteric artery.
Rarely, the hepatic or splenic artery originates directly from the aorta (see Figs. 11-11 and 11-12). An accessory left gastric artery may arise from the proximal splenic artery. Important organ anomalies include an accessory spleen (usually located in the tail of the pancreas), asplenia, polysplenia, and the ectopic or “wandering” spleen.25
Classic PV anatomy is found in 65% to 75% of the population. Surgically significant variants involve trifurcation of the main PV (type 2, 9% to 16%), origin of the right posterior branch from the main PV (type 3 or “Z type,” 8% to 13%), and separate segment VI or VII branches from the right portal vein (types 4 and 5, 7%).17,26
Accessory right hepatic veins are found in 25% or more of the population (Fig. 12-8). In about 3% of individuals, an inferior right hepatic vein (entering the IVC well below the diaphragm) is the dominant venous drainage for the right lobe.16
Figure 12-9 Acute occlusion of liver transplant hepatic artery (HA). A and B, Celiac arteriography shows complete HA obstruction along with collateral circulation from the right inferior phrenic artery (long arrow) and dorsal pancreatic artery (short arrow) into the intrahepatic branches (open arrow).
Cirrhosis is a progressive liver disease characterized by generalized necrosis, regeneration, and widespread fibrosis.27 Initially, inflammation or steatosis predominates. Fibrotic tissue then infiltrates the sinusoidal spaces and obstructs central veins while preserving portal venules. Masses (either micronodular or macronodular) begin to form, including regenerative, dysplastic, and malignant lesions. As the vascular resistance in the liver increases, PV pressure rises, but flow is still directed into the liver (hepatopetal). An imbalance in the relative activity of vasodilators (e.g., nitric oxide) and vasoconstrictors (e.g., endothelin-1) is responsible for the disturbances in hepatic, splanchnic, and peripheral hemodynamics that follow.28,29 With progression of cirrhosis, systemic and splanchnic vasodilation occurs, leading to increased cardiac output (a hyperdynamic circulatory state) and humorally mediated renal and hepatic vasoconstriction, which further impedes liver blood flow.30,31 Extrahepatic portal flow increases while intrahepatic portal flow decreases; in a compensatory fashion, hepatic arterial flow is augmented.
With end-stage cirrhosis, the liver shrinks, and portal venules and hepatic arterial branches are severely compressed by fibrotic infiltration and regenerating nodules. Hepatic vein outflow drops substantially. Intrahepatic pressure becomes so great that the portal system is decompressed through portosystemic collateral channels (see later discussion). Ultimately, flow in the PV is completely reversed (hepatofugal).
Although cirrhosis is by far the most frequent cause of portal hypertension, many other diseases can produce similar physiologic effects. Portal hypertension is traditionally classified by the site of obstruction relative to the hepatic sinusoids32 (Boxes 12-1 through 12-5). Some diseases affect one level and then extend to others. Disorders that cause elevated portal pressures proximal to or beyond the hepatic sinusoids are considered later in this chapter.
Box 12-1 Forms of Portal Hypertension
Box 12-2 Causes of Portal Vein Obstruction
Worldwide, hepatitis B and C infections are the leading cause of liver cirrhosis.33Alcoholic cirrhosis is the other common form of the disease in the United States and elsewhere. It evolves from an initial stage of fatty liver to sinusoidal scarring, formation of regenerative nodules (i.e., micronodular cirrhosis), and finally widespread fibrosis with liver shrinkage. Along with diabetes and metabolic syndrome, one consequence of the epidemic of obesity is the rapidly growing incidence of nonalcoholic fatty liver disease (NAFLD), including the particularly aggressive form of nonalcoholic steatohepatitis (NASH). These infiltrative conditions are now responsible for a significant fraction of cases of liver cirrhosis.34,35
Primary biliary cirrhosis is a cholestatic liver disease of immunologic origin that results in diffuse bile duct obstruction.36 It is typically seen in middle-aged women. In patients with chronic bile duct obstruction, portal fibrosis rather than diffuse cirrhosis is the cause for portal hypertension. Hepatic schistosomiasis, which is endemic in Africa and parts of Asia, causes infiltration of portal venules and periportal spaces, leading to presinusoidal obstruction.37Congenital hepatic fibrosis presents in late childhood with features of portal hypertension but normal liver function. Idiopathic portal hypertension and noncirrhotic portal fibrosis are rare conditions in which PV pressure is elevated without underlying liver disease.38 Destruction of intrahepatic portal radicles, portal fibrosis, and liver atrophy are characteristic. Cryptogenic cirrhosis encompasses all cases without an identifiable etiology, although many of these patients may have NAFLD or NASH.
Hyperdynamic portal hypertension, defined as increased flow through the portal venous system in the absence of resistive changes, is an unusual reason for elevated portal pressure. Two lesions that produce this physiology are an arterioportal fistula (which is often the result of penetrating trauma) or rupture of a hepatic artery aneurysm.39 In such cases, embolization of the fistula may be curative.
The most devastating consequence of portal hypertension is bleeding from ruptured gastroesophageal varices that serve as portosystemic collaterals to decompress the fibrotic liver.31 Varices develop in about half of patients with cirrhosis, but only about one third of those will bleed. Hemorrhagic risk correlates with variceal size, intraluminal pressure, and the patient’s Child-Pugh score (Table 12-3). Between 40% and 70% of patients die of the first episode of variceal hemorrhage. Bleeding is unlikely when the portosystemic pressure gradient is less than 12 mm Hg.40
Fiberoptic endoscopy is performed routinely in all patients with suspected variceal bleeding to document variceal size and stigmata of recent rupture (e.g., red wheals, cherry spots). Endoscopy may also identify an unrelated reason for acute gastrointestinal bleeding.
Ascites is another important complication of portal hypertension. The causes of ascites are manifold. Increased splanchnic blood flow elevates microcirculatory pressures and increases production of lymph, which leaks from the liver and intestines.41 In addition, peripheral arterial dilation (a response to vasoactive factors liberated from the gastrointestinal tract) leads to a reduction in effective plasma volume and retention of salt and water by the kidneys. The hepatic lymphatic system becomes overwhelmed, causing peritoneal leakage and a vicious cycle of further reduction in the plasma volume and worsening ascites.
Cirrhotic patients also are at risk for hepatic encephalopathy, spontaneous bacterial peritonitis, splenomegaly and pancytopenia, hepatocellular carcinoma, and ultimately complete hepatic failure. Less frequent complications include hepatorenal syndrome, hepatopulmonary syndrome, portopulmonary hypertension, and hepatic hydrothorax. Some of these conditions are related to the misregulation of vasodilating and vasoconstricting factors.42Hepatorenal syndrome is characterized by diffuse splanchnic and peripheral vasodilation and decreased effective plasma volume, prompting reflex renal vasoconstriction.43 Whereas the chronic form is treatable, the acute type is almost universally fatal (see later discussion).
Virtually all patients with suspected cirrhosis or portal hypertension undergo radiologic tests to prove the existence and assess the extent of liver disease and to detect occult hepatic malignancies. The primary indications for diagnostic invasive procedures are confirmation or quantitation of portal hypertension and transvenous liver biopsy.
Direct measurement of PV pressure is hardly ever needed for diagnosing portal hypertension; clinical studies have shown that the hepatic vein wedged (HVW) pressure is equal to PV pressure in most patients.44 The difference between HVW and IVC (or right atrial) pressure is the corrected sinusoidal pressure, which reflects the portosystemic gradient. However, the measurements are valid only when the PVs and hepatic sinusoids are in continuity. In patients with extrahepatic PV obstruction, splenic vein obstruction (“segmental” portal hypertension), or presinusoidal portal hypertension, this disconnection leads to a spuriously low HVW pressure. Normally, the portosystemic gradient is less than 5 mm Hg. Portal hypertension is defined as a gradient more than 6 mm Hg. The risk of bleeding from gastroesophageal varices becomes significant when the gradient is greater than 12 mm Hg.40
Free hepatic venography is done to assess the hepatic veins if obstruction is suspected, during the transjugular intrahepatic portosystemic shunt (TIPS) procedure, and sometimes during transvenous liver biopsy. Balloon-occluded or catheter-wedged hepatic venography with CO2 is routinely performed before creating TIPS to provide a target for the PV puncture. Hepatic veins have a pinnate (feather-like) branching pattern; portal veins branch dichotomously (Fig. 12-10).
With advanced cirrhosis, the hepatic arteries take on a “corkscrew” appearance because of increased arterial flow and liver shrinkage, and the spleen and splenic artery are enlarged (Fig. 12-11). The demand for hepatic artery flow can become so great that flow in the gastroduodenal artery is reversed. Occasionally, arterioportal shunting is seen (Fig. 12-12).
In the early stages of cirrhosis, PV flow is relatively normal. As the disease advances and portal hypertension becomes significant, several changes occur. The most important is the appearance of portosystemic collateral pathways, which include the following principal channels (Fig. 12-13):
Figure 12-13 Portosystemic collateral pathways. A through C, On reformatted coronal computed tomography (CT) scans, blood is diverted up the coronary vein (arrowhead), through large gastroesophageal varices (black arrows), and then to the azygous venous system (white arrow). Note shrunken nodular liver, enlarged spleen, ascites, and large bilateral pleural effusions. Paraumbilical vein drains the left portal vein through internal iliac venous channels into the inferior vena cava seen on CT scan (D,arrow). E, Early and (F) late phases of a direct portogram. Splenorenal shunt drains short gastric varices from the splenic hilum into the left renal vein (arrow), and then the inferior vena cava on early (G) and late (H) phases of a direct splenic venogram through a transjugular intrahepatic portosystemic shunt. Such shunts are occasionally embolized to prevent bleeding, relieve hepatic encephalopathy, or improve overall liver perfusion (I). Cecal varices (arrow) fill by direct portal vein injection (J) and then drain through systemic pelvic collaterals into the inferior vena cava (K,arrow).
Less common routes of decompression are gastric veins to pulmonary or intercostal veins, duodenal varices ultimately draining into the right gonadal vein (Fig. 12-14), left colic vein to left renal vein through the left gonadal vein, ileocolic vein to the IVC through hemorrhoidal veins, and intrahepatic portal venous branches to diaphragmatic veins. Gastroesophageal varices may be present but not seen on indirect portography.
Figure 12-14 Duodenal varices treated with embolotherapy. A, Late phase of celiac arteriogram shows splenic hilar varices and duodenal varices (arrow). B, The duodenal varices are better seen with selective gastroduodenal arteriography through a coaxial microcatheter. C, Pelvic collaterals were found to drain into the right ovarian vein and then into the inferior vena cava. D, The ovarian vein is catheterized, a microcatheter is negotiated to the site of the varices, and ethanolamine oleate was injected to induce sclerosis.
The direction of flow in the PV switches as portal hypertension worsens. With mild cirrhosis, PV flow is hepatopetal (see Fig. 12-3). As resistance increases, bidirectional flow in the PV may develop and the PV may not fill at all. With severe portal hypertension, the PV becomes an outflow conduit for the liver, and flow is hepatofugal (Fig. 12-15).
This imaging study is rarely (if ever) necessary. Before CT and MR angiography became so accurate, direct contrast injection of the splenic parenchyma was occasionally required to document patency of the splenic vein in patients with massive splenomegaly.
Tissue samples for histologic diagnosis of diffuse liver disease are usually obtained by percutaneous biopsy. For patients with certain conditions, transhepatic biopsy may be relatively unsafe and transvenous biopsy preferred (Box 12-6). This approach is used also in patients already undergoing hepatic vein catheterization for other reasons (e.g., diagnosis of portal hypertension, during the TIPS procedure).
From the right (or left) IJ vein, a 40-cm 10-Fr vascular sheath is advanced into the right or middle hepatic vein to the mid-portion of the vessel (Fig. 12-16). A stainless steel stiffening cannula is placed through the sheath. A flexible biopsy needle (e.g., Quick-Core or TLAB Patel set) is then inserted through the cannula and torqued within the hepatic vein until resistance is met. The device is buried in the parenchyma and triggered, and a piece of tissue is removed. Three or four specimens are needed to ensure that sufficient material is obtained for diagnosis.45,46
Figure 12-16 Transjugular liver biopsy in a posttranplant patient. Note prior coil embolization of gastroesophageal varices and placement of stents for portal vein stenosis. A, An angled catheter and sheath have been advanced well into the middle hepatic vein and venography done. B, With the metal cannula in place within the sheath, the entire mechanism is rotated anteriorly. The inner biopsy needle is advanced into the liver parenchyma and triggered to obtain liver tissue.
Liver tissue can be extracted in more than 97% of attempts. It may be slightly more difficult to obtain tissue in liver transplant patients with a “piggyback” type hepatic vein anastomosis47 (see later discussion). Biopsy samples are adequate for pathologic diagnosis 96% to 97% of the time.48–52 The major risk of the procedure is liver capsule perforation. Minor complications (including access site bleeding and cardiac dysrhythmias) are reported in up to 12% of cases. Less than 1% of patients experience serious life-threatening hemorrhage (usually from liver capsule perforation with intraperitoneal bleeding).46,48,49,52
Prophylactic treatment with beta-adrenergic blocking agents (often combined with isosorbide nitrate) is routinely prescribed in patients with documented gastroesophageal varices to lower portal venous pressure and thereby prevent initial or recurrent bleeding.53,54 If bleeding occurs, emergent management starts with resuscitation, prophylactic antibiotics, and pharmacologic therapy: somatostatin (or its analogue octreotide), vasopressin, or synthetic terlipressin (which constrict mesenteric arteries and reduces portal venous pressure and flow).55–57
Variceal band ligation or sclerotherapy is highly effective for the initial management and primary or secondary prevention of variceal hemorrhage.53,54,56–59 A sclerosing agent such as ethanolamine oleate or polidocanol injected into or around varices causes variceal thrombosis. Variceal banding is probably safer and more durable.54,57 About 70% to 90% of patients stop bleeding after one or two treatment sessions. However, sclerotherapy does not remedy the underlying hemodynamics of portal hypertension. Rebleeding is observed in about 10% to 15% of cases.31 Serious complications occur about 10% of the time.
The standard treatment for cirrhosis-related ascites is sodium and fluid restriction and diuretic therapy. Some cirrhotics with massive (tense) ascites are largely resistant to these measures. Intractable ascites can have a marked impact on overall quality of life. In such cases, frequent large volume paracentesis (>4 to 5 L) is necessary to diminish pain, nausea, and respiratory compromise. The application of volume expanders (e.g., intravenous [IV] albumin infusion) in this setting is controversial. However, large volume paracentesis is inconvenient for patients and does have risk.
Embolization of the coronary vein was quite popular before the widespread use of endoscopic sclerotherapy.60 Coils, with or without a sclerosing agent, are placed to obstruct the inflow vein. Although immediate results are excellent, rebleeding occurs in more than 50% of cases as new collateral channels develop.61 This procedure has limited use as an adjunct to TIPS placement (see later discussion) and for obliteration of ectopic varices.62
In Japan and other parts of Asia, balloon-occluded retrograde transvenous obliteration (BRTO) has become a popular modality for prevention or control of bleeding from isolated variceal clusters.63–65 Gastric and duodenal varices are notoriously difficult to treat with endoscopy because of their location and size. In some individuals, these massive shunts can also cause intractable hepatic encephalopathy.
Before BRTO, indirect portography via celiac and SMA arteriography is done to establish the portal venous anatomy and hemodynamics. The outflow vein for the varices (typically the left inferior phrenic/adrenal to left renal vein for gastric varices, right gonadal vein for duodenal varices) is selectively engaged with a diagnostic catheter (see Fig. 12-14). A 6-Fr balloon occlusion catheter (e.g., 11- or 20-mm diameter) is advanced into the main trunk and inflated, and venography is performed to classify the varices and collateral veins.
To induce thrombosis of simple varices, 10 mL of ethanolamine oleate 10% mixed with 10 mL of contrast material is slowly injected with the balloon inflated until the dilated veins are completely filled. The agent is left in place from 1 to 24 hours and then aspirated; the balloon is removed. More complex types of variceal communications may require use of a microcatheter or initial partial splenic embolization to reduce flow through the shunts.63,64 Obliteration of varices is documented with contrast CT.
In experienced hands, BRTO is successful in preventing further bleeding and improving encephalopathy in more than 80% of attempts.66 A major drawback to this approach is that purposefully closing down these natural shunts causes elevation of portal pressure and greater risk for esophageal variceal bleeding.67,68 There are some risks to using ethanolamine oleate, including renal failure, pulmonary edema, and anaphylaxis. In Asia it is routine to administer IV haptoglobin, which binds free hemoglobin, to prevent hemolysis-induced kidney damage.
In the past, surgical portocaval shunts were commonly recommended for management of these difficult patients.69,70 Side-to-side portacaval and mesocaval shunts are nonselective conduits that direct all portal blood flow away from the liver and return PV pressure to normal levels. The distal splenorenal (Warren) shunt is a selective communication that diverts flow from gastroesophageal varices but maintains intestinal portal flow to the liver. In this procedure, the splenic vein is divided, and the left gastric, right gastric, and gastroepiploic veins are ligated. Surgical mortality rates for all operative shunts are similar (10% to 20%). Rebleeding from varices occurs in about 5% to 15% of cases and is more frequent with selective shunts. Encephalopathy can be problematic.71 In most centers, operative shunts are rarely performed anymore.
Liver transplantation is the definitive treatment for relieving portal hypertension from chronic liver disease and provides the best long-term outcome compared with all other methods. The current overall 5-year survival rate for primary liver transplantation in the United States is 79%.72 Not all patients are candidates for transplantation, and donor organs are in short supply.
Current indications for TIPS have been formulated by several expert groups, including the American Association for the Study of Liver Diseases (AASLD)73–75 (Box 12-7). TIPS is most commonly performed for prevention of recurrent gastroesophageal variceal hemorrhage and management of refractory ascites. Given the inherent risks of the intervention, the fact that many patients with varices will never bleed and that only about half of those who do will rebleed, TIPS is reserved for patients who suffer one or more bleeding episodes that have failed endoscopic methods. However, this stipulation is being questioned. A recent randomized trial in high-risk cirrhotic patients with first variceal hemorrhage compared best medical therapy and endoscopic treatment against initial endoscopic treatment followed by urgent TIPS.76 Rebleeding was significantly less likely and survival significantly longer in the TIPS arm.
Refractory ascites implies that sodium restriction and maximum diuretic therapy are inadequate therapy. TIPS may afford better quality of life than repeated large-volume paracentesis, but encephalopathy often gets worse and survival is not clearly improved.77,78
Figure 12-17 Transjugular intrahepatic portosystemic shunt (TIPS) procedure with hepatocellular carcinoma and portal vein (PV) thrombosis. A, Contrast-enhanced magnetic resonance image shows a large hypervascular heterogeneous mass invading most of the right lobe of the liver. Right and left main portal veins are patent. Patient suffered several variceal bleeds, and a shunt was requested as a palliative measure. B, By the time the TIPS was performed, the tumor had invaded the portal vein (long arrow), and “cavernous transformation” has begun to bypass the obstructed PV (arrowheads). Note retrograde flow into the splenic vein (short arrow) and inferior mesenteric vein (curved black arrow).C, A portosystemic shunt was created with two Viatorr stent grafts from the patent central portal vein to the inferior vena cava.
Figure 12-18 Transjugular intrahepatic portosystemic shunt procedure with portal vein thrombosis. A, Entry is made into a distorted portal venous system. A stiff angled glidewire was ultimately advanced into the main portal vein. B, Portography shows tapered occlusion of the main portal vein (long arrow). Prominent gastric varices are seen (short arrow) along with a splenorenal shunt (C,arrowheads). D, Viatorr stent graft has been inserted; shunt is widely patent.
The decision to construct a TIPS demands thoughtful consideration by the patient, family, referring physician, and interventionalist. The procedure has a small but significant morbidity, and the immediate mortality rate approaches 1% to 2%. In addition, a substantial number of patients die soon afterward, largely from underlying liver disease but partly as a consequence of diversion of portal venous flow, which can precipitate fulminant hepatic failure.
When counseling patients and referring physicians, it is important to provide a frank assessment of the likelihood of survival following shunt creation. Patients can be stratified in several ways. The severity of liver failure is graded by the Child-Pugh classification (see Table 12-3). The MELD score (Mayo Endstage Liver Disease) has been adopted by many centers to predict outcomes in patients being considered for liver transplantation or TIPS. This score incorporates the serum bilirubin, creatinine, international normalized ratio, and recent need for dialysis (for calculation, go to www.mayoclinic.org/gi-rst/mayomodel6.html). Early mortality after TIPS insertion is especially high in patients with a MELD score greater than 18, Child-Pugh score greater than 12 (class C), APACHE severity of illness score greater than 18 to 20, or bilirubin greater than 3 mg/dL.93–96
Acute bleeding is controlled with variceal banding or sclerotherapy, systemic terlipressin or octreotide infusion, placement of an esophageal tamponade balloon, or some combination of these measures. Coagulation defects should be corrected and broad-spectrum antibiotics given before the procedure. Some cross-sectional imaging must be obtained beforehand to assess portal vein patency and exclude a large tumor. Color Doppler sonography is adequate. However, three-phase contrast-enhanced CT angiography is certainly better for assessing these parameters (PV patency, status of the hepatic veins, degree of ascites, liver size, presence of liver tumors or polycystic liver disease). Just as important, the operator can determine beforehand the suitability of the individual hepatic veins along with the best trajectory and distance to the portal vein.
The TIPS procedure can be performed with moderate sedation under the direction of the interventionalist. However, deep sedation or general anesthesia administered by a dedicated anesthesiologist is mandatory in unstable or uncooperative patients and helpful in all cases.
The standard access site is the right IJ vein (Fig. 12-19). The left IJ vein is preferred by some operators and should be considered if a second try is made after a failed first attempt. A 40-cm 10-Fr vascular sheath is advanced into the right atrium. Right atrial and IVC pressures are measured. If right atrial pressure is markedly elevated (>20 to 25 mm Hg), the interventionalist should proceed with caution. Fulminant right heart failure can occur after the shunt is created.
Figure 12-19 Transjugular intrahepatic portosystemic shunt procedure. A and B, Reformatted coronal computed tomography scans show small liver and enlarged spleen along with gastroesophageal varices (arrowheads) and a prominent splenorenal portosystemic shunt (long arrow). Also note bilateral pleural effusions. C, From the right internal jugular vein, the right hepatic vein has been catheterized. An 8.5-mm occlusion balloon was advanced deep into the vein and inflated. Carbon dioxide wedged hepatic vein injection opacifies the portal venous system to provide a target for portal vein puncture. The Roesch Uchida metal cannula was inserted. The cannula was rotated anteromedially, and the 5-Fr catheter stylet advanced. The crotch of the portal vein was entered. A marking pigtail was advanced for direct portography (D). The distance from portal vein entry to inferior vena cava entry was measured at 6 cm (arrowheads).E, A 10 mm × 2 cm × 6 cm Viatorr stent graft was inserted. Repeat portography shows a widely patent shunt with no filling of intrahepatic portal venous branches. Portosystemic gradient was 6 mm Hg. F, The coronary vein was catheterized. Gastroesophageal varices still opacify with forced injection, but portal decompression has been achieved and embolization is not necessary.
The right or middle hepatic vein is entered with a multipurpose angiographic catheter and steerable guidewire. If the right hepatic vein is small, has a very acute angle with the IVC, or is difficult to catheterize, TIPS can be created from the middle (or even left) hepatic vein. It is important to establish which vein is being used so that the intrahepatic puncture toward the PV is made in the appropriate direction. This step can be accomplished with steep oblique/lateral fluoroscopy or ultrasound interrogation. About 3% of the population has a dominant inferior right hepatic vein. In this situation, TIPS must be formed from the right common femoral vein (Fig. 12-20; see also Fig. 12-8).
Figure 12-20 Femoral transjugular intrahepatic portosystemic shunt (TIPS) procedure. A, From right internal jugular vein access, the major draining vein is an inferior right hepatic vein. TIPS cannot be created from above. B, Through a right common femoral vein approach, the standard TIPS set is used to enter the right portal vein. C, An uncovered Wallstent is placed to create the shunt (procedure done before advent of covered stents).
The site of PV puncture is critical. Because the portal vein bifurcation is extrahepatic in about one half of individuals, entry should be at or peripheral to this point to avoid extrahepatic puncture and the possibility of exsanguinating hemorrhage.16,100