Ch 96 hepatic vascular anomalies Flashcards

Question

History

Answer 1

- single congenital PSS present with signs of chronic or acute illness at a young age (1 month to 2 years) - Multiple acquired extrahepatic shunts and PVH-MVD are usually diagnosed in older animals - “failure to thrive” since birth - intermittent episodes of dullness, lethargy, or “bizarre” behaviors (41% to 90%; including stargazing, head pressing, - history of anesthetic intolerance - history of dysuria (20% to 53%) - polyuria and polydipsia - Abdominal effusion is seen in 75% of dogs with hepatic arteriovenous malformations

Answer 2

- poor medullary concentration gradient because of low blood urea nitrogen (BUN) concentration, - increased renal blood flow, - increased adrenocorticotropic hormone (ACTH) secretion with associated hypercortisolism, - psychogenic polydipsia

Answer 3

- clinical signs are milder in dogs with portoazygos or portophrenic shunts. These shunts are likely compressed by the diaphragm during respiration or with gastric distention after meals, resulting in improved portal perfusion - shunts that inserted caudal to the liver were more likely to result in clinical signs central nervous system - lethargy, ataxia, unresponsiveness, pacing, circling, blindness, seizures, and coma. gastrointestinal - vomiting, diarrhea, anorexia, pica, and, gastrointestinal bleeding - Preoperative gastrointestinal hemorrhage, may occur in 30% of large-breed dogs with intrahepatic PSS - Ptyalism is extremely common in cats (75%) urinary systems - present with signs of lower urinary tract disease - formation of ammonium urate calculi are common and can be associated with secondary bacterial urinary tract infections - calculi were documented in up to 36% - Glomerular filtration rate (GFR) and renal volume are increased in 81% congenital defects - Cryptorchidism - heart murmurs - Copper-colored irises inappropriate for the breed

Answer 4

- microcytic, normochromic, nonregenerative anemia - hypoalbuminemia (50%), - reduced BUN (70%), - hypocholesterolemia - hypoglycemia - Mild to moderate increases in serum liver enzyme activities (uncommon values >4x the high end of the reference) - ammonium biurate crystalluria - hyposthenuric or isosthenuric - bladder stones 30-36% - Hyperammonuria from the deficient hepatic urea cycle + hyperuricacidemia from a deficiency uric acid cycle > excessive ammonia and urate excretion by the kidneys. - These compounds can precipitate into crystals or stones in the kidney or bladder

Answer 5

- Bile acids are produced in the liver, stored in the gallbladder, released into the intestines for fat digestion, and then reabsorbed and recirculated. - Their levels are influenced by gallbladder contraction, intestinal transport, and liver function. - In PSS, bile acid levels remain persistently high due to improper circulation. - Increased postprandial bile acids are highly sensitive indicators of PSS, but variations exist (can be up to 100% sensitive) - Some animals show elevated levels without liver disease, such as Maltese dogs - False positives can occur due to liver disease, certain medications, or gastrointestinal disorders, - false negatives may result from delayed intestinal absorption, gallbladder dysfunction, or maldigestion.

Answer 6

- when bile acid results are inconclusive - Blood ammonia originates from the gastrointestinal tract and is converted into urea by the liver. - conversion is impaired, leading to increased ammonia levels. - Baseline ammonia levels are less sensitive 62-88% of PSS cases. - False positives and negatives occur - Sensitivity improves with postprandial ammonia testing. ammonia tolerance test - administering ammonium chloride and measuring the body's ability to clear it - highly sensitive (95-100%) for PSS - should be avoided in animals with already high ammonia levels. - Ammonia test results are influenced by diet, handling, and lab processing.

Answer 7

- significantly higher than those of healthy Beagle dogs - suspected mechanism of preattenuation increase was reduced hepatic clearance secondary to poor intrahepatic portal blood flow, which improves after shunt closure - may be useful in evaluating successful attenuation of congenital PSS

Answer 8

- loss of approximately 65% to 80% of factors needs to occur before prolongation in PT or activated partial thromboplastin time (aPTT) results. - spontaneous bleeding is very rare - prolonged aPTT (>20 seconds) - prolonged PT (>9 seconds).

Answer 9

- most common include bile duct proliferation, hypoplasia of intrahepatic portal tributaries, hepatocellular (lobular) atrophy, arteriolar proliferation or duplication, lipidosis and cytoplasmic vacuolar changes - histologic features associated with a poor prognosis included fibrosis, biliary hyperplasia, and necrosis. - Significant histologic improvement is not expected in dogs or cats that undergo partial attenuation of congenital PSS, even if those animals improve clinically - Dogs with noncirrhotic portal hypertension often have more significant fibrosis extending into the parenchyma, particularly along the portal tracts or even bridging to other portal areas or central veins

Answer 10

Abnormalities on survey abdominal radiographs that are suggestive of, but not diagnostic for, PSS include microhepatia (60% to 100% of dogs and 50% of cats with PSS) and bilateral renomegaly.

Answer 11

- detecting radiolucent uroliths in dogs and cats - ecreased number of hepatic and portal veins, a subjectively small liver, and an anomalous vessel - Extrahepatic shunts are more difficult to diagnose than intrahepatic PSS - Multiple extrahepatic shunts are even harder to find and are typically located near the left kidney. - variation in reported accuracy - sensitivities 68% to 95% - specificity 67% to 100% - operator and experience dependent. - color-flow and pulse-wave Doppler imaging may detect changes in flow direction - extrahepatic PSSs have hepatopetal flow through the portal vein - Ultrasound-guided percutaneous splenic injection of agitated saline > microbubbles

Answer 12

- (99mTc mebrofenin) and using transcolonic or transsplenic administration - If a PSS is present, radioisotope often reaches the heart within 4 seconds after administration - 100% sensitive and specific for diagnosis of shunting

Answer 13

- gold standard - noninvasive, fast, and accurate - Dual-phase computed tomographic angiography provides a complete evaluation of portal and hepatic vasculature - valuable for preprocedural planning - provided information about various tributary vessels that could be overlooked during surgical exploration MRI - magnetic resonance angiography provides a three-dimensional, preoperative image of the shunt - more expensive than good CT Portovenography - Operative mesenteric portography - at the time of laparotomy with a portable fluoroscope (C-arm). - Sensitivity 85%, 91%, and 100% in dorsal, right lateral, and left lateral recumbency - improved with use of digital subtraction

Answer 14

hypoglycemia, hydrocephalus, atlantoaxial subluxation, idiopathic epilepsy, gastrointestinal parasitism, hypoadrenocorticism, protein-losing enteropathy primary hepatopathies

Answer 15

Bacterial translocation or decreasing bacterial byproduct absorption (ammonia) - Cleansing enemas - Oral lactulose: 0.5–1.0 mL/kg PO q6-8hr (results in entrapment of luminal ammonia in the form of ammonium and a decrease in colonic bacterial numbers) - ab? Coagulopathy (symptomatic; postoperative) - Fresh frozen plasma: 10–15 mL/kg over 2–3 hr - Vitamin K1: 1.5–2.0 mg/kg SC Gastrointestinal ulceration (intrahepatic, AVM) - Omeprazole: 1.0–2.0 mg/kg/d PO Seizure control - Benzodiazepines (controversial) > Diazepam is not recommended for animals with hepatic encephalopathy or other causes of liver failure - Phenobarbital (16 mg/kg IV divided into four doses for loading over 12–24 hr). Maintenance: 20–30 mg/kg/d PO - Propofol: 0.5–1.0 mg/kg IV bolus; CRI at 0.05–0.1 mg/kg/min (controversial) - Keppra: 20 mg/kg (≤60 mg/kg) PO or IV every 8 hr (there is limited evidence to support this) Decrease cerebral edema - Mannitol: 0.5–1.0 g/kg bolus over 20–30 min Nutritional support - Moderate protein restriction: 18%–22% for dogs and 30%–35% for cats Hepatoprotective therapy - chronic conditions that are unable to be fixated [e.g., MVD] - SAMe: 17–22 mg/kg/d PO (hepatoprotective, antioxidant, and antiinflammatory properties) - Ursodeoxycholic acid: 10–15 mg/kg/d | Glucose should be supplemented in intravenous fluids

Answer 16

- varied outcomes. - Some dogs developed progressive liver fibrosis. - In a study of 27 dogs, MST 9.9 months, with intrahepatic shunts having worse outcomes. 51.8% euthanized within a year (encephalopathy). - Dogs with extrahepatic PSS had better survival - Another study of 27: 89% medically treated died (median survival >2.3 years), compared to 21.6% of surgically treated dogs (MST not calculated). - Long-term prognosis is generally better for dogs with primary portal vein hypoplasia (PVH-PVD), with 92% surviving surgery remains the preferred treatment for congenital PSS when feasible.

Answer 17

complete ligation 46/64 (71.9%) → 16/20 (80.0%) complete resolution of clinical signs vs 4/10 (40.0%) partial attenuation - complete ligation → longer MST (not reached) vs medical (1730d) - PANS in 1/64 – minor, self-resolving - portal hypertension 5/62 (8.1%): 2/16 (12.5%) partial, 3/46 (6.5%) complete ligation - 1/2 partial ligation with portal hypertension euthanased - outcome: good-excellent 20/20 (100%) complete, 9/10 (90.0%) partial, 19/32 (59.3%) medical

Answer 18

survival time longer with surgical attenuation - 7.3% peri-op mortality - shorter survival associated with: non-sx, HE at dx, higher neutrophil count - medical management → more common continued clinical signs and medical tx

Answer 19

- cachectic, encephalopathic, or unstable should be managed medically before sx (min. 2 weeks) - treat hypoalbuinaemia - preoperative anticonvulsant therapy remains a debated topic (retrospective study with levetiracetam, no seizure post op when give > controlled studies are needed) - generalized seizures that are not controlled by routine medical management should be placed on phenobarbital anaesthetic - avoid agents metabolized by the liver, highly protein bound, or hepatotoxic - opiod (remifentanyl) - propofol - Hypothermia should be anticipated - CVC ideal

Answer 20

- partial or complete acute occlusion with ligatures or more gradual attenuation with ameroid constrictors, cellophane bands, or hydraulic occluders. - Most animals will not tolerate acute complete occlusion - Gradual attenuation is preferred to reduce the risk for postoperative complications - should be attenuated as close to their insertion sites as possible so that blood flow from all tributaries of the shunt is redirected - diaphragm may be opened if more exposure is needed - portal vein lies within the mesoduodenum ventral to the hepatic artery and is identified by retracting the duodenum to the left.

Answer 21

Intraop mesenteric portovenography Portal catheterisation Intra-op Doppler ultrasound

Answer 22

- often terminate on the caudal vena cava cranial to the renal veins at the level of the **epiploic foramen** - epiploic foramen can be exposed by gently retracting the duodenum ventrally and to the left. - In normal: no large vessels entering the caudal vena cava between the right renal and hepatic veins - Rarely located within the caudal abdomen (e.g., colonocaval shunts) Gastrophrenic or splenophrenic shunts - travel along the lesser or greater curvature of the stomach and ventral surface of abdominal portion of the esophagus - become enveloped in the fascia transversalis of the diaphragm's central tendon

Answer 23

- usually traverse the diaphragm along its crura at the aortic hiatus or through the esophageal hiatus - may be necessary to enter the omental bursa by tearing through the ventral leaf - stomach is retracted cranially - examine the dorsal bursal recesses for abnormal vessels that **penetrate the diaphragmatic crura**.

Answer 24

commonly seen near the kidneys and within the intestinal mesentery but can occur anywhere in the abdomen

Answer 25

8-13cmH2O (6-10mmHg)

Answer 26

- max portal pressure 17-24cmH2O (12.5-17.6mmHg) - max change in portal pressure 9-10mmH2O (6.6-7.35mmHg) - max decrease CVP 1cmH2O, (0.74mmHg)

Answer 27

- When a shunt cannot be located during surgery - Before abdominal closure the surgeon should obtain a liver biopsy sample to rule out other hepatic diseases - Overdose of iodinated contrast materials can lead to hypotension, arrhythmias, cardiac arrest, and contrast-induced renal failure - Identification of congenital PSS with operative mesenteric portography depends on patient positioning - Some clinicians use operative mesenteric portography to evaluate intrahepatic portal development. A portogram is obtained before surgical attenuation and during complete temporary occlusion - the absence of arborizing intrahepatic vasculature on preligation portograms was correlated with a greater occurrence of postoperative complications

Answer 28

1200mg iodine/kg Overdose - hypotension, arrhythmias, cardiac arrest, renal failure

Answer 29

- inner ring of casein surrounded by stainless steel sheath. - Casein = hygroscopic substance that swells as it slowly absorbs body fluid, reducing the ring's **internal diameter by 32%**. - stimulates a fibrous tissue reaction that causes gradual shunt occlusion within 2 to 5 weeks after placement. - attenuation is most rapid during the first 3 to 14 days - thrombus formation could result in more rapid obstruction of partially attenuated shunts - size based on shunt diameter; preferably internal diameter larger than the shunt (5-9mm - gas sterilized and therefore should not be used until 12 to 24 hours after sterilization to allow residual ethylene oxide to be released from the casein - Measurement of portal or central venous pressures is unnecessary with ameroid constrictor placement as long as the shunt has not been attenuated at the time of surgery.

Answer 30

- from regenerated cellulose or from thin films made of polyester or olefin - reports rarely define the material with which the bands are made, making comparison of postoperative results difficult. - 1 × 10-cm strip is folded longitudinally into thirds - securing the ends together with three or four large surgical clips placed from alternating directions - cellophane bands cause fibrous tissue reaction and gradual shunt occlusion - used to attenuate shunt to less than 3 mm in diameter, complete occlusion was demonstrated in dogs and cats that underwent cellophane banding without intraoperative attenuation - Synthetic materials used to make the thin film bands in these later studies may cause greater inflammatory reaction - reduced inflammatory response in cats Real cellophane has a microscopic fiber pattern with striations, will burn like paper. There is no bubbling, blistering or melting

Answer 31

- silicone and polyester cuff connected by tubing to a vascular access port - small amount of sterile saline is injected through the port every 2 weeks - closure not depend on fibrous tissue formation

Answer 32

- Nonabsorbable synthetic monofilament (e.g., polypropylene) is recommended in cats because of the risk for shunt recanalization - Failure of silk suture has also been reported in a dog - shunt is temporarily occluded with a Rumel tournique > evaluated for evidence of portal hypertension - rapid increase in portal pressure of at least 4 cm H2O. - If necessary, a portogram can be performed to verify - a surgeon's throw is tied on the ligature, and the ligature is gradually tightened. With each incremental decrease in shunt diameter, the animal is evaluated if revision required - leave a polypropylene suture with long ends - At that time the suture is elevated, and hemostatic clips are placed across the two ends to compress the shunt while portal pressures are evaluated. - obviates the need for dissection around the vessel.

Answer 33

- Nonencephalopathic dogs can often tolerate complete shunt ligation - up to 86% of animals require partial attenuation - A second surgical procedure to occlude a partially ligated shunt is therefore not recommended unless clinical signs reoccur. portal and central venous pressures - maximum portal pressure of 17 to 24 cm H2O (12.5 to 17.6 mm Hg), maximal change in portal pressure of 9 to 10 cm H2O (6.6 to 7.35 mm Hg), - maximal decrease in central venous pressure of 1 cm H2O (0.74 mm Hg) - arterial pressure maximum of 5 mm Hg or 15% or less, and the heart rate should not increase dramatically - not be used as the sole criteria for degree of shunt attenuation because blood pressures may vary with the depth of anesthesia, hydration status visual inspection - pallor or cyanosis of the intestines - increased intestinal peristalsis, - cyanosis or edema of the pancreas - increased mesenteric vascular pulsations.

Answer 34

* Extravascular ligation (usually of shunt or draining hepatic vein, occassionally of feeding portal branch) > under ultrasonic guidance, To improve exposure of the vessels, the surrounding parenchyma can be removed with suction * Intravascular ligation (not really one anymore) * Intravascular coiling

Answer 35

- left hepatic vein is responsible for draining the left hepatic division. - Shunts often appear as dilated vessels between the left lateral and medial liver lobes. - treated by ligating the shunt or the hepatic vein. - Complete ligation of the left hepatic vein may cause temporary hepatic congestion but does not have long-term effects on hepatic function in healthy dogs. - If the shunt or hepatic vein is not identifiable, attenuation of the left portal vein branch may be necessary. Surgical Dissection Approach: - transecting the left triangular ligament. - left hepatic vein is usually visible where it meets the caudal vena cava, but the rest is surrounded by hepatic tissue. - Tissue removal may be done by crushing or suctioning - forceps are used to apply sutures or constriction devices like a cellophane band or ameroid constrictor. - If the vessel is too short or thick, an ameroid constrictor may not be feasible.

Answer 36

**Dissection of the Left Portal Vein:** - left liver lobes are retracted cranially to expose the hilus (medial and lateral separated) - If the lobar hepatic artery and biliary duct obstruct, double-ligate and transect - Dissection of the left lateral portal vein branch may require cutting through the hepatoduodenal ligament. - A peritoneal window is created over the portal branch

Answer 37

- Right divisional shunts are usually detected by identifying the enlarged portal vein branch and by palpation of a soft, compressible area within the affected liver lobe - Most hepatic veins of the central and right divisions are completely encompassed within hepatic tissue > shunts of these divisions are often treated surgically by ligation of the supplying portal vein branch or by intravascular techniques. Indirect Suture Passage - If the right portal vein branch cannot be directly dissected safely, a suture can be passed around it indirectly by dissection of the main and left portal veins

Answer 38

- portal vein branch supplying the shunt is often too close to the main or left portal vein to permit dissection. - surgical repair is usually limited to intravascular approaches. - Because these are fraught with potential complications, referral for intravascular coiling is preferred.

Answer 39

- liver can tolerate up to 20 minutes of blood flow occlusion - practically limited to 10 to 15 minutes to avoid effects of prolonged hypotension and intestinal ischemia

Answer 40

- maintained on intravenous fluids - blood glucose - monitored for hypoglycemia, hypothermia, delayed anesthetic recovery, hemorrhage, seizures, and signs of portal hypertension. - A protein-restricted diet and lactulose are continued after surgery until liver function improves. - Frequently animals can be weaned off lactulose within 4 to 6 weeks. - Bile acids and a biochemical panel are evaluated 2 to 3 months after the surgery. - function is normal, medical management is discontinued> slowly weaned over 2 to 3 months after surgery, removing one treatment at a time (antibiotics, then lactulose, then diet) - In many patients, bile acid concentrations do not return to reference ranges (<10 µmol/L and <15 µmol/L for preprandial and postprandial samples, respectively); therefore assessment may be based on clinical response - moderately increased, medical management is continued, and animals are rechecked 5 to 6 months after surgery - Normalization of bile acid not correlated with long-term outcome - persistently increased bile acid concentrations ok as long as routine biochemical parameters improve and clinical signs are well controlled

Answer 41

* Hypogylcaemia 44%, 29% of which are refractory to dextrose * Haemorrhage and anaemia * Portal hypertension 2-14% with acute ligation * Seizures and encephalopathy 3-18% dogs, 8-22% cats * thrombus * arrythmia * peritonitis, * bacterial hepatitis, * sepsis * sudden death * recurrence of clinical signs

Answer 42

- reported in 44% of dogs - Toy breeds are most commonly affected. Initial treatment should include intravenous boluses of 25% to 50% dextrose and initiation of oral - 29% of affected dogs, hypoglycemia is refractory to intravenous dextrose

Answer 43

- Intraoperative and postoperative hemorrhage are uncommon - acute anemia can be seen postoperatively in dogs - Changes in coagulation usually do not cause clinical bleeding and normalize after shunting resolves and liver function improves - Portal hypertension may result in hemorrhage because of gastrointestinal or incisional bleeding. - use of gastroprotectants postoperatively, particularly in patients that have undergone intrahepatic shunt attenuation.11,125 Use of lifelong antacid therapy (omeprazole 0.5 to 1.5 mg/kg/d) in dogs with intrahepatic PSS

Answer 44

- 2% to 14% of patients undergoing acute suture ligation - less common in patients undergoing gradual shunt occlusion - Portal hypertension can be exacerbated by overhydration, vocalization, defecation, and large meals Clinical signs - hypovolemic shock - abdominal pain, - abdominal distention (ascites) - diarrhea or vomiting tx - supported with oxygen, warmth, intravenous crystalloids - omeprazole - analgesics, - systemic antibiotics. - evaluated for hypotension and DIC - clotting times are prolonged, fresh frozen plasma or fresh whole blood - Ligature removal immediately with severe clinical signs > DIC or nonresponsive hypotension. - Spironolactone or furosemide for chronic ascites - ascites may be a precursor of multiple acquired shunt formation

Answer 45

- 3% to 18% of dogs and 8% to 22% of cats - Seizures may occur up to 80 hours after surgery and are not associated with hypoglycemia, hyperammonemia, or attenuation technique - Lethargy, facial twitching, ataxia, muscle fasciculation, blindness, and abnormal vocalization are often apparent before generalized seizure activity. cause - unknwon - decreases in endogenous inhibitory central nervous system benzodiazepines agonist levels or imbalances in excitatory and inhibitory neurotransmitters tx - Hypoglycemia and electrolyte disorders should be ruled out - midazolam or diazepam (0.5 mg/kg IV). - Levatiracetam, - Phenobarbital, because of its lower lipid solubility, may take up to 30 minutes to reach therapeutic concentrations - propofol (4 to 8 mg/kg) and maintained under anesthesia on a propofol continuous rate infusion (0.1 to 1.0 mg/kg/min) - Intravenous levetiracetam and rectally instilled lactulose are continued. - Mannitol (1 g/kg over 20 minutes) is administered intravenously every 6 hours to reduce intracranial swelling. - Partial or total parenteral nutrition - propofol is discontinued after 12 to 24 hours > trial - some animals may require 72 hours of anesthesia to resolve seizure activity - In general, **half of affected dogs die or are euthanized** and those that survive often continue to have visual deficits and other neurologic problems for weeks to years.

Answer 46

theories of etiology: CNS derangement: - altered metabolism – decreased endogenous benzodiazepines (theory is that a decrease in systemic concentrations of endogenous benzodiazepines derived from the gastrointestinal tract occurs after shunt attenuation,fails to explain the occurrence of PANS after partial ligation and delayed attenuation techniques >Administration of benzodiazepines has also proven unreliable - increased manganese - not associated with post-op hyperammonemia (occurs with normal levels, absence of preoperative HE in some dogs and the refractory nature of PANS in comparison to preoperative HE suggest an alternative etiology than postoperative continuation of HE) - adapted to a state of altered metabolism and that a change in this altered metabolic state postattenuation precipitates PAS - concurrent brain disease - acquired brain disease – no strong evidence for ischemic/hypoxic injury - peri-op hypoglycemia (occurs when normal, hypoglycaemic-induced brain lesions?) - peri-op electrolyte disturbances – unclear - post-op portal hypertension – no evidence in support - infections disease – not identified PANS incidence 1.6-27.3%, post-attenuation seizures (PAS) 0-18.2% risk factors: immediate pre-op HE, increasing age, potentially breed, shunt morphology (more with extrahepatic than intra) - not associated: method/degree of attenuation ( The incidence of PAS after suture ligation 0%-18.2%, TFB 1.8%-18.2% and and AC placement is 0%- 13.0%), pre-op neuro signs/seizures, sx or ga time, post-op change in Na or serum osmolality prophylactic antiepileptics do not prevent PANS Tx - generalised PAS often refractry to tx - propfol > good for PAS - no evidence for levetiracetam survival: - 30-day 0-100 with PANS, 0-75% with PAS - PANS mortality associated with generalised seizure activity - px factors for positive survival: pre-op seizures, focal seizures only - survivors → long term survival with resolution of majority of PANS signs

Answer 47

Hyponatraemia - cause unknown

Answer 48

Continued flow through original shunt Presence of a second shunt Multiple acquired shunts Congenital PVD Unrelated disease Animals with clinical signs or biochemical changes should have repeat imaging. Surgical intervention is recommended for patients with a second congenital shunt or clinical signs related to persistent flow through the original shunt.

Answer 49

Extrahepatic: - Suture: 2-32% - Ameroid: 7% - Cellophane: 6-9% - Good-to-excellent outcome in 78-94% Intrahepatic: - Suture: 6-23% - Ameroid: 0-9% - Cellophane: 27% - Probability of long term survival withou recurrence 60-61% at 1yr, 55-56% at 2-4yr | most common death within 1 month is severe persistent neurologic signs

Answer 50

Comparing long-term outcomes is difficult because of variations in follow-up times and standards for satisfactory outcome - good to excellent outcomes were noted in 78% to 94% - Most dogs continued to have mildly increased bile acid concentrations. - Outcomes are better in patients that undergo complete shunt attenuation.95 In one study, 35% of animals were euthanized an average of 43 months after partial shunt ligation because of clinical recurrence of signs - Some dogs that have undergone partial ligation cannot tolerate complete ligation in a subsequent surgery because of portal hypertension - Good to excellent outcomes were noted in 70% to 89% of dogs with intrahepatic portosystemic shunts that underwent ameroid constrictor placement, 76% to 100%

Answer 51

* Anaemia - poorer long-term outcome * Increased BUN assoc with a decreased short-term survival * Increased WBC/neutrophils assoc with decreased survival and unsuccessful long-term outome * Higher pre-op albumin and TP assoc with better short term survive for intrahepatic PSS * Extrahepatic ameroid: for every decreased in albumin by 1g/dL, odds of continued shunting increased 3.76 times. For every increase of albumin by 1, odds of unsuccessful outcome decreased by 0.4times

Answer 52

- portal pressures before ligation and during temporary occlusion and change in portal pressure after ligation were not correlated with long-term outcome - those that tolerate complete acute ligation usually have a better outcome and are less likely to develop multiple acquired shunts - some studies show no difference in the long-term outcome when comparing complete and partial ligation

Answer 53

Ameroid: 0-4.5% mortality Cellophane: 0-22% Suture: 4-20% Good-to-excellent outcome in: - Ameroid: 33-75% - Cellophane: 57-80% - Suture: 56-75% Generalised seizures in 8-28% and central blindness in up to 44% (usually resolves within 2 months)

Answer 54

20 % | most often found in the right or central divisional lobes

Answer 55

- Multiple acquired extrahepatic PSSs are also evident - surgical treatment of hepatic arteriovenous malformations is resection of the affected lobe - Some authors recommend preplacement of Rumel tourniquets for temporary inflow occlusion - If the appropriate artery has been occluded, portal pressure should decrease. Complications - hemorrhage, - portal hypertension, - systemic hypotension, - bradycardia, - thrombus formation.

Answer 56

Pretreatment with atropine or glycopyrrolate to prevent reflex bradycardia (Branham reflex)

Answer 57

* Perioperative survival 75-91% * Long-term outcome fair or good in 38-57% * 75% continue to require dietary or medical management (continue to have multiple acquired shunts)

Answer 58

PSS: Jugular vein AV malformations: femoral artery

Answer 59

- Portal pressures should be assessed before intervention, as ~5% of dogs have a portal-caval pressure gradient. - Procedure: Initial Access & Vessel Selection: - A guide wire is inserted via the jugular vein into the cranial vena cava, right atrium, and caudal vena cava. - A catheter is advanced to identify the shunting vessel (hepatic vein to portal vein). - Contrast angiography confirms vessel anatomy and shunt location. Stent Placement & Coil Embolization: - measure the size of the intraabdominal vena cava during positive-pressure ventilation - A self-expanding nitinol stent is deployed in the caudal vena cava to prevent coil migration. - The catheter is advanced through the stent into the shunting vessel. - places thrombogenic coils into the shunt, monitored under fluoroscopy. - Coils are added until portal pressure reaches a safe level (~7 mmHg increase, not exceeding 15 mmHg final pressure). Outcomes & Considerations: - Coil embolization immediately reduces shunt flow, allowing a clot to form and occlude the vessel. - Additional coils may be required later if liver function does not improve (~18% of cases). - In rare cases (~3%), temporary balloon occlusion is used if portal perfusion remains high. - If portal pressure changes are not excessive, complete shunt attenuation can be achieved using coils, vascular plugs, or covered stents.

Answer 60

- Increase the portal pressure by 7mmHg, but not higher than a final portal pressure of 15mmHg - Coils are added until the mouth of the shunt is coered or the portal pressure is no greater than 10cmH2O (7mmHg) above baseline or a final pressure of approx 20cmH2O (15mmHg)

Answer 61

Omeprazole to reduce the risk of GI ulceration - With addition of lifelong antacids, mortality dropped from 25% to 3.2%

Answer 62

- fewer than 15% had perioperative complications - coil migration (reduced by caval stent) - excessive bleeding at jugular catheter site, - aspiration - PANS (6%). - mortality rates are approximately 5% (gastrointestinal bleeding, cardiac arrest, or euthanasia because of neurologic sequelae) - gastrointestinal bleeding (long-term mortality rate of 30%, which was due to gastrointestinal disease/ulceration in 50% of the dogs that died > significantly reduced using antacids) - Portal hypertension has not been a problem (likely due to the fact that shunt attenuation occurs postsinusoidally) > also reduces the likelihood of restoring complete hepatic portal flow without some degree of shunting (trade-off between risk and benefit) - persistence of abnormal clinical, biochemical, and scintigraphic evaluations common

Answer 63

- Cyanoacrylate glue embolization may be used to occlude the anomalous vascular communications under fluoroscopic guidance - Within a few seconds of infusion, the glue polymerizes and occludes the small communications - All tributaries must be occluded to resolve the condition > careful evaluation of hepatic arterial perfusion after initial embolization is important to avoid incomplete occlusion - venous occlusion of hepatic arteriovenous malformation is now being investigated (safer than arterial) Complications (rare). - Nontarget vascular embolization of vessels may occur I.e. portal circulation, acquired shunts, pulmonary, gastroduodenal artery, or other branches of the hepatic artery) - second embolization and partial hepatectomy required - survival rate was 100% - most dogs require lifelong medical management because of continued shunting through multiple acquired PSSs.

Answer 64

1:1 or 1:2 ratio with Ethiodol - makes mixture radioopaque and slows polymerisation Powdered tantalum - additional radioopacity

Answer 65

- animals with chronic portal hypertension dt MVD, cirrhosis, AVM, acute or gradual attenuation of congenital PSS - often present with ascites (transudate), gastrointestinal hemorrhage, and signs of hepatic encephalopathy. tx - controlling the clinical signs of hepatic encephalopathy - slowing the progression of the liver disease - Ligation of the individual shunts is not considered effective because they are relieving the portal hypertension (unless cause of underlying liver disease is resolved) - Survival times in animals undergoing caval banding is similar to those treated medically - prognosis is poor (though mnat are asymptamostic of devveloped atyer single PSS ligation)

Answer 66

In humans, hepatic arterial blood flow changes in response to the reduction in portal blood flow. The so-called hepatic arterial buffer response (HABR) is an intrinsic regulatory mechanism,

Answer 67

Retrospective. 20 cats, PSS attenuated with ameroid constrictor long term: excellent 15/18, good 1/18 , poor in 2/18 complications 5/20 (25%) including blindness (two cats > resolved in 2 weeks), ascites (one cat), head pressing (one cat), and seizures and death (one cat) excellent or good outcome (88.9%) ARC can result in resolution of clinical signs and biochemical abnormalities in the majority of cats. Postoperative seizures 8–33% of cats undergoing gradual and 22% of cats undergoing acute partial or complete ligation

Answer 68

Prospective. 20 dogs. blood tests in dogs with EHPSS to assess shunt closure Transsplenic portal scintigraphy to confirm closure. Fasting ammonia: highest specificity 100% with 81.5% sensitivity Serum hyaluronic acid: highest sensitivity 96.9% and 81% specificity Test performances can be improved by combining these tests Ammonia > within normal limits, further blood tests recommended due to false negatives. Increased FA > suggestive of persistent shunting SBA > do not seem of added value after surgical attenuation. unclear to what extent they should decrease as a measure of surgical attenuation. Ideal sensitivity of 100% > ruled out persistent shunt without further imaging required. If persistent shunting > imaging is always advised to differentiate original EHPSS or due to development of MAPSS stainless steel staples/ameroid > small tributaries can also be missed using CTA because of streaking artifacts

Answer 69

high specificity (Spin) - chance of a negative test when the disease is not present - highy likely to give a negative result in an animal without disease - thus, if positive result, very likely animal has the disease (good confirming test)

Answer 70

A retrospective case series Seven cats were diagnosed with a left divisional shunt, three with a central divisional shunt and two with a right Three > complete acute suture attenuation, eight cats underwent partial suture attenuation, four of which received complete suture ligation at a second surgery, and one cat underwent partial attenuation with a thin film band. Six cats (50%) developed postattenuation neurological signs (PANS) after first surgery and two cats (17%) died or were euthanased due to severe PANS long term excellent in five cats (63%), dissected extravascularly immediately cranial to the liver at insesion at cranial vena cava

Answer 71

polyethylene band attenuation in 60 dogs Post-op complications (16.7%), mortality 6.7%. Persistent shunting (17%) Long-term outcomes excellent or good in 81.8%, poor in18.2%. (68.2%) not receiving any medical treatment comparable to previous reports of TFBs with the benefit of being pre-sterilised and pre-folded. 9% to 47% persistent shunt cellophane band noncellulose material for thin film banding (polyolefin), good long-term outcomes (Nelson 2016,Otomo 2020)

Answer 72

Intercostal thoracotomy for portoazygos PSS in 3 dogs right-sided intercostal thoracotomy was performed. No surgical complications or post-attenuation seizures were observed when vessels are attenuated prior to their final insertion > distal tributaries may still enter cranial to the attenuation site, resulting in persistent shunting all PAS cross the diaphragm to terminate within the thorax > thoracic or abdominal approach best?

Answer 73

laparoscopic PSS attenuation (TFB) in 20 dogs - conversion 5/20 (25%) - complications: self-limiting portal hypertension 3/20 - can be performed in dogs, in particular for a CEPSS located in the epiploic foramen (3 or 4 port technique) severe portal hypertension requiring revision 1/20 - good outcome in all dogs after resolution of complications - right paramedian approach for epiploic foramen, otherwise left paramedian

Answer 74

Percutaneous shunt vessel embolisation with Amplatzer vascular plugs with splenophrenic shunts: four cases No major intraop complications. No seizures or signs of portal hypertension. improvements in ammonia values were observed in all cases. AVP > increase density and flow disturbance and result in rapid occlusion

Answer 75

25 client-owned dogs that underwent gradual attenuation of a cEHPSS, of which 19 had a closed cEHPSS and 6 developed multiple acquired portosystemic shunts (MAPSS) following surgery 1 of 19 (5%) dogs with closed cEHPSS and 4 of 6 (67%) dogs with MAPSS had urolithiasis at long-term follow-up. Three (50%) dogs with MAPSS developed new uroliths. Dogs that developed MAPSS following cEHPSS surgery are at greater risk of urolithiasis compared to those with closed cEHPSS. Furthermore, ammonium urate uroliths might dissolve (partially) if portosystemic shunting ceases to exist.

Answer 76

incidence: PANS: 14.3-62.0%, PAS 0-32.0% - risk factors: lower grade intra-op postocclusion mesenteric portovenography, - not associated: shunt morphology, signalment, method/degree of attenuation, presence of pre-op neuro signs - no evidence/support for the use of prophylactic anti-epileptics - px for recovery variable, dependent on severity of signs - cats surviving to discharge (PANS: 66.7-100%, PAS 25.0-100%) → possible long-term survival - persistence/recurrence of neuro signs not uncommon

Answer 77

morphology: dogs: spleno-caval, left gastro-phrenic, left gastro-azygous and right gastric vein account for 94% cats: spleno-caval, left gastro-phrenic, left gastro-caval, left gastro-azygous - first 3 → 92% of shunts - proposed development of majority of shunts developing as a result of preferential blood flow → subsequent formation of shunt from essentially normal portal vasculature

Answer 78

revealing five distinct shunt types: left gastrophrenic, right gastrocaval (types Ai, Aii and Aiii), splenocaval, colocaval and left gastro-azygos confirmed four consistent sites of communication between the anomalous shunting vessel and the systemic venous system: 1. the caudal vena cava at the level of the epiploic foramen; 2. the left phrenic vein at the level of the oesophageal hiatus; 3. the azygos vein at the level of the aortic hiatus; 4. caudal vena cava or iliac vein at the level of the 6th or 7th lumbar vertebrae.

Answer 79

retrospective Complication and survival rates in this cohort were similar to or better than those reported in previous studies evaluating PTCE and open surgical techniques for treatment of IHPSS in dogs. Intra- and postoperative complication rates were 20% (4/20) and 5% (1/20), respectively, and included hypotension, bradycardia, hypercapnia, ventricular premature contractions, hypothermia, and regurgitation. all dogs survived to discharge. Clinical signs resolved in 95% (19/20) of the dogs a median of 21 days after the procedure. One- and 2-year survival rates were 92%. Three dogs had died by the time of data collection; 2 of these dogs died of causes related to the IHPSS

Answer 80

- for those that survive >30 days - 30/50 (60%) PAS and 20/50 had other neuro signs; 24/50 (48%) resolved neuro signs by discharge - 15/30 PAS dogs had recurrence of seizures - 50% new neuro signs after discharge - >6 month survival 45/50 (90%) - outcome: 27/33 (82%) owner-assessed QOL ‘high’ - 67% of neuro signs (other than seizures) present at discharge resolved within 1 month - blindness or vision impairment less likely to resolve Twenty-nine (88%) dogs were alive at the time of questionnaire completion a mean of 1,986 days (SD, 1,237 days) postoperatively, whereas 4 (12%) dogs had died or been euthanized **Half of the dogs with postattenuation seizures had a reoccurrence.**

Answer 81

theories of etiology: CNS derangement: - altered metabolism – decreased endogenous benzodiazepines (theory is that a decrease in systemic concentrations of endogenous benzodiazepines derived from the gastrointestinal tract occurs after shunt attenuation,fails to explain the occurrence of PANS after partial ligation and delayed attenuation techniques >Administration of benzodiazepines has also proven unreliable - increased manganese - not associated with post-op hyperammonemia (occurs with normal levels, absence of preoperative HE in some dogs and the refractory nature of PANS in comparison to preoperative HE suggest an alternative etiology than postoperative continuation of HE) - adapted to a state of altered metabolism and that a change in this altered metabolic state postattenuation precipitates PAS - concurrent brain disease - acquired brain disease – no strong evidence for ischemic/hypoxic injury - peri-op hypoglycemia (occurs when normal, hypoglycaemic-induced brain lesions?) - peri-op electrolyte disturbances – unclear - post-op portal hypertension – no evidence in support - infections disease – not identified PANS incidence 1.6-27.3%, post-attenuation seizures (PAS) 0-18.2% risk factors: immediate pre-op HE, increasing age, potentially breed, shunt morphology (more with extrahepatic than intra) - not associated: method/degree of attenuation ( The incidence of PAS after suture ligation 0%-18.2%, TFB 1.8%-18.2% and and AC placement is 0%- 13.0%), pre-op neuro signs/seizures, sx or ga time, post-op change in Na or serum osmolality prophylactic antiepileptics do not prevent PANS Tx - generalised PAS often refractry to tx - propfol > good for PAS - no evidence for levetiracetam survival: - 30-day 0-100 with PANS, 0-75% with PAS - PANS mortality associated with generalised seizure activity - px factors for positive survival: pre-op seizures, focal seizures only - survivors → long term survival with resolution of majority of PANS signs

Answer 82

Congenital portosystemic shunts in 50 cats included 40 extrahepatic and 10 intrahepatic shunts. Postattenuation neurological signs were recorded in 31 (62%) Five of 31 cats with PANS did not survive to discharge Preoperative levetiracetam did not prevent

Answer 83

there was a significant difference between the median sHA concentration in dogs with closed EHPSS vs. those with persistent shunting sHA is a promising non-invasive biomarker that can help to determine liver perfusion after surgical attenuation of EHPSS. Hyaluronic acid is locally metabolised and, when it reaches the blood via the lymphatic system, it is rapidly catabolised, mainly by hepatic sinusoidal endothelial cells. Consequently, increased serum (s)HA concentrations in dogs with PSS can be an indication of decreased clearance secondary to decreased liver perfusion.

Answer 84

- TFB (polyolefin fibre = polypropylene) placed to result in no attenuation - no difference in survival to discharge (TFB 95.3%, AC 97.4%) - post-op seizures: 10/123 (8.1%) overall, TFB 10.6%, AC 2.6% - not different - incidence not associated with levetiracetam administration - ongoing clinical signs at follow up: overall 22% - TFB 19.0%, AC 21.6% - not different - similar long-term outcomes with low post-op morbidity and mortality non–cellulose-based TFB led to short- and long-term outcomes similar to ARC Neither reimaging nor revision surgery was performed in any dog, so persistent shunting could not be confirmed.

Answer 85

cohort of dogs treated with suture attenuation and compare results with those obtained from a healthy control cohort The median long-term health-related quality of life score was excellent for both intrahepatic and extrahepatic shunt cases and similar to that of control dogs. The long-term portosystemic shunt clinical sign scores for both intrahepatic and extrahepatic congenital portosystemic shunt dogs were significantly worse than

Answer 86

The overall incidence of PAS was low (8%). Prophylactic treatment with LEV does not afford protection against development of PAS. Surgically treated dogs should continue to be monitored closely during the **first 7 days postoperatively for seizures** 30 day survival 23/75 (30.7%)

Answer 87

recommended 4-layer TFB with medium polymer locking ligation clip or titanium ligation clip to secure TFB

Answer 88

Dogs treated with CB sustained more minor postoperative complications and were hospitalized longer than dogs treated with PTCE. The 1-year and 2-year survival rates were 89% for the CB group and 87% and 80% for the PTCE group, respectively. The proportion surviving at 5 years was 75% and 80% for CB dogs and PTCE dogs, respectively. Conclusion: CB and PTCE are associated with similar short-term and intermediateterm survival. PTCE is a minimally invasive alternative to CB via celiotomy. However, CB allows concurrent abdominal procedures requiring the same approach.

Ch 96 hepatic vascular anomalies Flashcards

(121 cards)