Ultrasonography and portography in the diagnosis of shunt portoazigos in a dog: case report / Ultrassonografia e portografia no diagnóstico de shunt portoázigos em um cão: relato de caso

Portosystemic shunt (PSS) is an anomalous vascular connection between the portal venous system and the systemic circulation. These deviations connect the main portal vein (PV) or some portal branches to the vena cava (VC) or, less commonly, to the azygos vein (AV). The purpose of this case report was to describe the diagnosis of PSS in a dog classified as porto-azygos. This diagnosis is considered uncommon compared to other portosystemic shunts using ultrasonography and portography. The subject was a male dog, Yorkshire, 8 months old, presented neurological signs characterized by head press, ataxia, tremors and episodes of temporary blindness and deafness. Ultrasonographic examination revealed a dilated and curved anomalous vessel with approximately 0.6cm of diameter and turbulent flow seen through pulsed and color Doppler, and segmental dilation of the azygos vein. The portography revealed enhancement by iodinated contrast in the jejunal vein, the portal vein and an anomalous vessel flowing towards the azygos vein in the craniodorsal region of the abdomen. The PSS was surgically corrected with an ameroid constrictor. Ultrasonography and portography were effective at detecting and characterizing the portoazygos shunt despite some limitations.(AU)

Shunt portossistêmico (SPS) é uma comunicação vascular anômala entre o sistema venoso portal e a circulação sistêmica. Esses desvios comunicam a VP ou alguma de suas tributárias à veia cava ou, menos comumente, à veia ázigos (VA). O objetivo do presente estudo foi descrever o diagnóstico, por meio de ultrassonografia e portografia, de um caso de shunt extra-hepático em cão, classificado como portoázigos e considerado incomum quando comparado aos demais tipos de desvio portossistêmico. Um cão, macho, raça Yorkshire, oito meses de idade, chegou ao Hospital Veterinário da Universidade Federal de Minas Gerais apresentando sinais neurológicos, caracterizados por andar apoiando a cabeça na parede, ataxia, tremores, episódios de cegueira e surdez. Ao exame ultrassonográfico, observou-se vaso anômalo calibroso e tortuoso de aproximadamente 0,6cm de diâmetro e fluxo turbulento ao Doppler pulsado e colorido, bem como dilatação segmentar da VA. A portografia revelou realce de contraste iodado em veia jejunal, porta e vaso anômalo (shunt) seguindo em direção à VA em região dorsal do abdômen. Foi realizada a correção cirúrgica do SPS por meio de anel ameroide. A ultrassonografia e a portografia foram eficientes na detecção e caracterização do shunt portoázigos, mesmo que com algumas limitações.(AU)

Evaluation of hepatic tumor portal perfusion using mesenteric angiography: A pilot study in 5 dogs.

BACKGROUND: Mesenteric angiography is a sensitive method for visualizing portal perfusion in the dog. OBJECTIVES: To evaluate hepatic portal perfusion in dogs with incompletely resectable hepatic tumors using mesenteric angiography. ANIMALS: Five client-owned dogs with incompletely resectable hepatic tumors evaluated with mesenteric angiography. METHODS: Retrospective case series. Electronic medical records at the Animal Medical Center were analyzed to identify dogs that underwent mesenteric portography to determine blood flow to nonresectable hepatic tumors and subsequently determine ideal routes for transarterial embolization, vascular stent placement, or both. The images obtained from mesenteric angiography were analyzed and compared to those obtained from computed tomography angiography. RESULTS: Portography was accomplished using direct mesenteric venography in 3 dogs with hepatocellular carcinoma (HCC), cranial mesenteric arteriography in 1 dog with hepatic adenoma or well-differentiated HCC, and via splenic arteriovenous fistula in 1 dog with diffuse hepatic hemangiosarcoma metastases. Mean pixel densities in areas of hepatic tumor growth identified statistically significant decreases in portal blood flow (P = .02) compared to normal hepatic parenchyma. CONCLUSIONS AND CLINICAL IMPORTANCE: Initial findings indicate that the blood supply to large and metastatic hepatic tumors in dogs may correlate with that in humans, such that the majority of the tumor blood supply arises from the hepatic artery and not the portal vein. Differences in blood supply between normal hepatic parenchyma and hepatic tumors might be exploited by developing selective tumor therapies such as arterial embolization or chemoembolization that largely spare normal liver tissue. Further investigation is warranted.

Comparison of contrast-enhanced multidetector computed tomography angiography and splenoportography for the evaluation of portosystemic-shunt occlusion after cellophane banding in dogs.

BACKGROUND: Many patients with a congenital extrahepatic portosystemic shunt (PSS) do not tolerate an immediate shunt closure. Therefore, slow progressive techniques were developed. To evaluate the success of shunt closure diagnostic imaging is essential to identify possible residual blood flow through the shunt vessel. There is a lack of information about the reliability of computed tomography angiography (CTA) for evaluating residual flow through a PSS after treatment. The purpose of this prospective study was to compare the results of CTA with splenoportography. Three months after cellophane banding CTA and splenoportography were performed in 20 dogs and reviewed by three independent examiners, respectively. In both imaging modalities the presences of a residual shunt was judged as present or absent and the extent of visibility of portal vasculature was recorded. RESULTS: Based on the evaluation of the splenoportography residual flow through shunt was present in 6 dogs. The classification of residual shunt present or absent showed a substantial to perfect agreement (κ = 0.65-1.00) between the observers in splenoportography and a slight to moderate agreement (κ = 0.11-0.51) for CTA. Sensitivity and specificity varied between 0.50 and 1.00 and 0.57-0.85, respectively. Significant correlation between CTA and splenoportography for the classification of residual shunt was present only in one observer but not in the other two. CONCLUSION: More studies were classified as residual shunt positive with CTA compared to splenoportography. It remains unclear which methods do reflect reality better and thus which method is superior. The greater inter-rater agreement for splenoportography suggests a greater reliability of this technique.

Imaging diagnosis--celiacomesenteric trunk and portal vein hypoplasia in a pit bull terrier.

The computed tomography (CT) imaging findings of a celiacomesenteric trunk (CMT) in a 1-year-old dog with primary hypoplasia of the portal vein (PHPV) are described. Computed tomography angiography revealed acquired porto-systemic shunts secondary to portal hypertension and a common origin of the celiac and cranial mesenteric arteries. The imaging findings and the association of a CMT with other vascular diseases have never been reported in dogs. The recognition of this rare arterial anomaly should prompt to investigate possible concurrent vascular diseases and may influence the planning of abdominal surgeries.

Histopathological findings in the livers of cats with a congenital portosystemic shunt before and after surgical attenuation.

Histopathological changes are reported in the livers of cats with congenital portosystemic shunts (CPSS) before and after surgical attenuation. Medical records, portovenograms and liver biopsies from cats treated surgically for CPSS were reviewed. Biopsies were graded for histopathological features characteristic of CPSS. Of 40 cats with CPSS included in the study, all had portal vein hypoplasia and arteriolar hyperplasia at initial surgery, 20 (50 per cent) had hepatocyte swelling with microvesicular vacuolar change, 17 (42.5 per cent) had fibrosis, 12 (30 per cent) had hepatocyte swelling with macrovesicular vacuolar change, 8 (20 per cent) had biliary hyperplasia and 2 (5 per cent) had haemosiderin within Küpffer cells. Cats with macrovesicular vacuolar change were significantly older than cats without (P = 0.001), with median ages of 18.5 months and 8.5 months, respectively. Twenty-five cats had partial attenuation of the CPSS at initial surgery, and 16 of these had follow-up biopsy samples. There were no significant differences in the histopathological features of biopsies before and after partial attenuation. From first to second surgery, there was a significant improvement in intrahepatic vasculature on portovenography both before (P = 0.001) and after (P = 0.039) temporary complete attenuation. Following partial CPSS attenuation, there was no significant change in histopathological features despite an improvement in intrahepatic vasculature on portovenography.

Association between hepatic histopathologic lesions and clinical findings in dogs undergoing surgical attenuation of a congenital portosystemic shunt: 38 cases (2000-2004).

OBJECTIVE: To review hepatic histopathologic lesions in dogs undergoing surgical attenuation of a congenital portosystemic shunt (CPSS) in relation to clinical findings and tolerance of complete surgical attenuation. DESIGN: Retrospective case series. ANIMALS: 38 dogs that underwent surgical attenuation of a CPSS. PROCEDURES: Hepatic histologic examination findings and medical records of dogs undergoing surgical attenuation of a single CPSS between August 2000 and July 2004 were reviewed. Liver biopsy specimens were obtained from 38 dogs during surgery prior to complete (n = 16) or partial (22) attenuation of a CPSS and from 13 of the same dogs a median of 3 months following surgical attenuation. RESULTS: Portal tracts were inadequate for interpretation in 2 liver biopsy specimens. Liver biopsy specimens obtained prior to surgical attenuation of a CPSS had a lack of identifiable portal veins (13/36 dogs), hepatic arteriolar proliferation (25/36), ductular reaction (5/36), steatosis (16/38), and iron accumulation (32/38). Lack of identifiable portal veins on histologic examination was associated with increased hepatic arteriolar proliferation, decreased tolerance to complete surgical CPSS attenuation, and decreased opacification of intrahepatic portal vessels on portovenography. Ductular reaction was always associated with failure to tolerate complete surgical attenuation of a CPSS. Surgical CPSS attenuation resulted in significant clinical, serum biochemical, and portovenographic changes indicative of improved liver function, but only subtle changes in hepatic histologic examination findings. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs without identifiable intrahepatic portal veins that had a ductular reaction on hepatic histologic examination were less likely to tolerate complete attenuation of a CPSS.

Association of mesenteric portovenographic findings with outcome in cats receiving surgical treatment for single congenital portosystemic shunts.

OBJECTIVE: To determine whether hepatic portal vascularity assessed via intraoperative mesenteric portovenography (IMP) is related to outcome in cats undergoing surgical attenuation of a congenital portosystemic shunt (CPSS). DESIGN: Retrospective case series. ANIMALS: 25 cats, each with 1 CPSS, in which IMP was performed before and after temporary complete occlusion of the shunting vessel to provide complete (n=9) or partial (16) shunt attenuation. PROCEDURES: Medical records were reviewed for signalment, clinical history, postoperative complications, clinical outcome, and results of bile acids stimulation testing. Portovenograms obtained before and after shunt occlusion were graded to determine whether degree of intrahepatic portal branching was correlated with degree of shunt attenuation, clinical or biochemical factors, postoperative complications, or outcome. In 12 of the 16 cats that had partial CPSS attenuation, procedures were later repeated to achieve complete (n=9) and additional partial (1) CPSS attenuation. RESULTS: Degree of opacification of the intrahepatic portal vessels increased significantly (higher portovenogram grade) after CPSS attenuation. The median portovenogram grade assigned after temporary shunt occlusion at the first surgery was significantly higher in cats that did not have postattenuation neurologic complications or neurologic signs at follow-up than in cats that did. It was also higher in cats that had a better clinical response to surgery versus those that had a poor response and in cats with reduced preprandial and postprandial serum bile acids concentrations at follow-up versus those that did not. CONCLUSIONS AND CLINICAL RELEVANCE: IMP may be used to help predict complications and outcome following surgical treatment of CPSS in cats.

Comparison of transplenic multidetector CT portography to multidetector CT-angiography in normal dogs.

We evaluated transplenic injection of iodinated contrast medium for computed tomography (CT) assessment of the portal vasculature. Specific aims were to: (1) establish a protocol for transplenic transplenic CT portography using a 40-row multidetector scanner; (2) compare transplenic CT portography to dual-phase CT angiography in terms of image quality, opacification of the portal system, and contrast enhancement of the portal vasculature and liver; (3) compare personnel exposure during transplenic CT portography and transplenic portal scintigraphy. Seven juvenile dogs underwent transplenic portal scintigraphy, CT angiography, and transplenic CT portography. Transplenic portal scintigraphy and CT angiography were performed using previously established protocols. For transplenic CT portography, a 20- or 22 gauge needle attached to an extension set was placed into the splenic parenchyma using CT guidance. Iodinated contrast medium (175 mg I/ml) was administered, and CT acquisition was started at the time of the injection. Transplenic CT portography was simple, rapid and provided more intense enhancement of the splenic and portal veins, with a lower contrast medium dose (median dose: 525 mg I for transplenic CT portography, 7700 mg I for CT angiography), but caused inconsistent intrahepatic portal branches and parenchymal opacification due to streamlining and streak artifacts. Despite significantly lower attenuation values in the portal vein, CT angiography provided sufficient enhancement for vessel identification and more consistent parenchymal hepatic enhancement. Personnel radiation exposure rate was higher during transplenic CT portography (0.0725 mSv/min) compared with transplenic portal scintigraphy (0.000125 mSv/min). As transplenic CT portography requires an average injection time of 1 min per study; over 650 [corrected] studies must be performed before reaching the maximum permissible whole body dose of 0.05 [corrected] Sv.

Association of portovenographic findings with outcome in dogs receiving surgical treatment for single congenital portosystemic shunts: 45 cases (2000-2004).

OBJECTIVE: To determine whether hepatic portal vascularity, as assessed by intraoperative mesenteric portovenography (IMP), is related to outcome in dogs undergoing attenuation of single congenital portosystemic shunts (CPSSs). DESIGN: Retrospective case series. ANIMALS: 45 dogs, each with a single CPSS, in which IMP was performed before and after temporary complete occlusion of the shunting vessel and that underwent complete (17 dogs) or partial (28 dogs) CPSS attenuation (surgery 1). PROCEDURES: Medical records were reviewed for signalment, clinical history, and bile acids stimulation test results. Intrahepatic portal vessel (IPV) opacification in pre- and postocclusion portovenograms was graded to determine whether the degree of opacification was correlated with the degree of shunt attenuation, clinical or biochemical factors, or long-term clinical outcome. In 17 of 28 dogs that had partial CPSS attenuation, these procedures were subsequently repeated (surgery 2) to achieve complete (14 dogs) or further partial (3 dogs) CPSS attenuation. RESULTS: Compared with preattenuation findings, IPV opacification increased significantly after partial or complete CPSS attenuation. The degree of IPV opacification before and after CPSS occlusion (surgery 1) was greater in dogs that tolerated complete versus partial CPSS attenuation and was correlated positively with age. The degree of IPV opacification following CPSS occlusion (surgery 1) was maximal in all dogs without encephalopathy and was correlated negatively with follow-up preprandial serum bile acids concentrations and positively with clinical improvement. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggest that IMP can be used to assess changes in IPV blood flow and help predict outcome following attenuation of single CPSSs in dogs.

A suspected case of ornithine transcarbamylase deficiency in a cat.

An 18 month-old, intact female American Shorthair cat was presented for evaluation of stunted growth and postprandial depression. Fasting serum ammonia and serum bile acid concentrations were above reference ranges at 396 microg/dl and 6.5 micromol/ l and their postprandial concentrations were 785 microg/dl and 9.5 micromol/l, respectively. The initial tentative diagnosis of a portosystemic shunt was excluded by mesenteric portography and histopathology of the liver. The cat was then suspected of a urea cycle enzyme deficiency and its urine was analyzed by gas chromatography-mass spectrometry. A presumptive diagnosis of ornithine transcarbamylase deficiency was made on the basis of the detection of orotic acid and uracil.

Successful treatment by percutaneous transvenous coil embolization in a small-breed dog with intrahepatic portosystemic shunt.

A Miniature Dachshund, 3-month-old, 3.1 kg, was diagnosed as an intrahepatic portosystemic shunt (PSS) with the shunting vessel in 6-mm diameter. Percutaneous transvenous coil embolization (PTCE) was performed with a stainless steel coil in 8-mm diameter. Intraoperative portal pressure elevated about 2.5 times after one-stage coil occlusion. Two weeks after the PTCE, serum bile acid levels reduced within the normal range. The portogram showed complete occlusion of the shunting vessel 4 months after the PTCE. Approximately 3 years after the PTCE, the patient has shown no clinical signs. PTCE could be performed more easily and less invasively in a small-breed dog. It is therefore suggested that PTCE is a promising therapeutic technique in canine intrahepatic PSS.

Diagnostic imaging of congenital porto-systemic shunts in dogs and cats: a review.

An overview of clinical, laboratory, and diagnostic imaging features of congenital porto-systemic shunt (PSS) in dogs and cats is presented through the analysis of recent literature, and personal case log. Particular emphasis is given to diagnostic accuracy of ultrasonographic examination of PSS in the evaluation of shunt vessel anatomy, and of ancillary findings such as abnormalities of portal vein flow, portal branches, and liver size. Operative mesenteric portography to obtain information on PSS morphology and position, and quantitative hepatic scintigraphy, which allows the calculation of shunt fractions, are also described. Limitations for each diagnostic imaging technique are given.

Use of portocaval venografts with ameroid constrictor placement and hepatic lobectomy for treatment of intralobular intrahepatic portocaval shunts in four dogs.

Liver lobectomy for complete attenuation of intrahepatic portosystemic shunts appears to be a safe and effective surgical treatment. When the intrahepatic shunt vessel can be definitively palpated within a liver lobe or its presence confirmed portographically, liver lobectomy represents a technically simple and effective method of complete shunt attenuation. To maintain portal pressure at an acceptable value after lobectomy, an extrahepatic portocaval shunt vessel can be created by use of an external jugular vein graft. A second shunt vessel can be created if portal pressure remains increased after placement of 1 shunt. Gradual and safe attenuation of the shunt vessel is achieved by placement of an ameroid constrictor on the extrahepatic graft at the time of the initial surgery.

Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs.

Transvenous retrograde portography for identification and characterization of portosystemic shunts in dogs A method for transvenous retrograde portography (TRP) in dogs suspected to have a portosystemic shunt (PSS) and results in 20 dogs are described. For TRP, dogs were anesthetized and positioned in left lateral recumbency A dual-lumen balloon-tipped catheter was inserted into the right jugular vein and advanced into the azygos vein. The balloon was inflated to occlude the azygos vein, and contrast material was injected during fluoroscopic evaluation. The catheter was then positioned in the caudal vena cava just cranial to the diaphragm. The balloon was again inflated to occlude the vena cava, and contrast material was again injected. Once a shunt was identified, selective catheterization was attempted with a guide wire and angled catheter. A PSS was identified in 18 of the 20 dogs. In 10 of the 18, the shunt vessel could be selectively catheterized, allowing measurement of portal pressures while the shunt was occluded with the balloon. In 1 dog, results of TRP were normal, but subsequent exploratory celiotomy revealed a single extrahepatic PSS, which was surgically attenuated. The other dog in which results of TRP were normal did not have a macroscopic PSS. In dogs suspected to have a PSS, TRP may be a useful adjunctive diagnostic test that is less invasive than operative mesenteric vein portography and allows measurement of portal pressures before and after temporary shunt occlusion.

Portosystemic shunt in an alpaca cria.

A 5-month-old alpaca cria was examined for chronic poor growth and repeated episodes of diarrhea. Examination of feces for parasites yielded negative results. Serum bile acid and blood ammonia concentrations were high. Subsequent examination by ultrasonography, percutaneous splenic portography, and colonic scintigraphy did not reveal evidence of a portosystemic vascular anomaly. Exploratory celiotomy with mesenteric vein portography revealed a colonic vein shunt in the caudal portion of the abdomen from the caudal vena cava to the portal vein. The shunt vessel was ligated without incident. Following surgery, the cria began to gain weight and was more alert. Eighteen months after surgery, the cria was doing well, although it had loose feces and was slightly small for its age. Portosystemic shunts are rare in cattle and horses but should be considered in alpacas with chronic poor growth when parasitism has been ruled out.

Influence of patient positioning on sensitivity of mesenteric portography for detecting an anomalous portosystemic blood vessel in dogs: 34 cases (1997-2000).

OBJECTIVE: To determine whether sensitivity of detecting an anomalous portosystemic blood vessel during operative mesenteric portography varied with patient positioning. DESIGN: Retrospective study. ANIMALS: 34 dogs with a portosystemic shunt diagnosed via scintigraphy or surgery. PROCEDURE: Portograms were evaluated for a portosystemic blood vessel. Sensitivity was calculated from results obtained with dogs in left lateral, right lateral, and dorsal recumbency and from results obtained with dogs in 2 or 3 positions. Differences in sensitivity among positions and between 2 examiners were evaluated. RESULTS: Sensitivity was 85, 91, and 100% in dorsal, right lateral, and left lateral recumbency, respectively. Sensitivity was lower in dorsal recumbency than in left lateral recumbency, although differences were not significant. There was no significant difference between sensitivity of results obtained in dorsal and right lateral recumbency or right lateral and left lateral recumbency. Sensitivity for combined right lateral and dorsal positions was 97%, which was better than that in dorsal recumbency alone, although the difference was not significant. Because sensitivity in left lateral recumbency was 100%, there was no need to evaluate the improvement obtained by combining the result of this position with the results of other positions. CONCLUSION AND CLINICAL RELEVANCE: Results of mesenteric portography varied with patient positioning. The optimal position varied among patients but left lateral recumbency may be better and dorsal recumbency worse. Sensitivity may be improved by performing the test with the patient in orthogonal recumbent positions.

Transvenous coil embolization of an intrahepatic portosystemic shunt in a dog.

To treat an intrahepatic portosystemic shunt in a young dog, thrombogenic material was placed into the vessel lumen (transvenous coil embolization) under fluoroscopic control. One coil was placed into the shunt, followed one month later by two additional coils. Transvenous embolization may become a useful method in the treatment of some portosystemic shunts.

Detection of portal and systemic bacteremia in dogs with severe induced hepatic disease and multiple portosystemic shunts.

OBJECTIVE: To determine existence of portal and systemic bacteremia in dogs with induced severe hepatic disease, compared with clinically normal dogs, before and after vena caval banding. ANIMALS: 6 control dogs and 10 dogs with induced severe hepatic disease and multiple portosystemic shunts (PSS). PROCEDURE: Dogs of the diseased group were given dimethylnitrosamine (2 mg/kg of body weight, PO) twice weekly until multiple PSS developed. Surgery was performed on dogs of both groups, and blood for baseline aerobic and anaerobic bacterial culture was collected from catheters placed in the portal and hepatic veins and caudal vena cava. All dogs underwent vena caval banding, and blood for aerobic and anaerobic bacterial culture was collected from the portal and hepatic venous catheters at 120, 240, and 360 minutes after banding. RESULTS: Compared with control dogs (16% gram-positive and 84% gram-negative bacteria), diseased dogs had significantly higher percentage of gram-positive bacteria (42% of positive culture results, P < or = 0.01) and significantly lower percentage of gram-negative bacteria (58% of positive culture results, P < or = 0.01) isolated. Pseudomonas aeruginosa was isolated most frequently from dogs of both groups; more than 1 organism was isolated from 5 dogs of each group. Antimicrobial susceptibility included that to aminoglycosides (particularly amikacin), fluorinated quinolones, and imipenem. CONCLUSION: Portal and systemic, predominantly gram-negative, bacteremia is present in catheterized, clinically normal dogs and dogs with dimethylnitrosamine-induced hepatic disease and multiple PSS.

Surgical management of multiple congenital intrahepatic shunts in two dogs: case report.

OBJECTIVE: To present details of an unusual type of portosystemic shunt and its surgical management in two dogs. ANIMALS: Two young dogs that had a tentative diagnosis of a portosystemic shunt on the basis of clinical signs and serum biochemical abnormalities. Abdominal ultrasonography and contrast portography demonstrated multiple intrahepatic shunts. In both cases, the multiple shunts arose from a single branch of the portal vein. OUTCOME: It was possible to locate and attenuate flow through the shunts via a transportal venotomy under conditions of hepatic vascular occlusion. Clinical and biochemical abnormalities resolved after surgery in both dogs. Postoperative sonography revealed complete obliteration of the shunt plexus in one of the dogs.