USE OF INTRAOPERATIVE MESENTERIC PORTOVENOGRAPHY IN CONGENITAL PORTOSYSTEMIC SHUNT SURGERY

Anatomical classification of feline congenital extrahepatic portosystemic shunts based on CT angiography: A SVSTS and VIRIES multi-institutional study in 231 cats

The prevalence of anatomical-based subtypes of feline congenital extrahepatic portosystemic shunts (EHPSS) has not been completely elucidated. The goal of this study was to use CT angiography to create an anatomical-based nomenclature system for feline congenital EHPSS. Additionally, subjective portal perfusion scores were generated to determine if intrinsic portal vein development was associated with different shunt conformations or patient age at the time of CT. The SVSTS and VIRIES list services were used to recruit cases. Data collected included patient DOB, gender, breed, weight, CT date, and reported diagnosis. Shunts were classified based upon (1) the shunt portal vessel(s) of origin, (2) the shunt systemic vessel(s) of insertion, and (3) any substantial portal vessels contributing to the shunt. Additionally, hepatic portal perfusion was subjectively scored between 1 (poor/none) and 5 (good/normal) based on the caliber of the intrahepatic PVs. A total of 264 CT scans were submitted from 29 institutions. Due to exclusion criteria, 33 (13%) were removed, leaving 231 CT scans to be included. Twenty-five different EHPSS anatomies were identified with five classifications accounting for 78% of all shunts (LGP [53%], LGC-post [11%], LCG [7%], LGC-pre [4%], and PC [4%]). Shunt origin involved the left gastric vein in 75% of the described classifications. Significant differences were identified among the five most common shunt types with respect to age at the time of CT scan (P = .002), breed (P < .001), and subjective portal perfusion score (P < .001). This refined anatomical classification system for feline EHPSS may enable improved understanding, treatment comparisons, and outcome prediction for cats with these anomalies.

Congenital Portosystemic Shunts in Dogs and Cats: Treatment, Complications and Prognosis

Congenital portosystemic shunts (CPSS) are a common vascular anomaly of the liver in dogs and cats. Clinical signs of CPSS are non-specific and may wax and wane, while laboratory findings can raise the clinical suspicion for CPSS, but they are also not specific. Definitive diagnosis will be established by evaluation of liver function tests and diagnostic imaging. The aim of this article is to review the management, both medical and surgical, complications, and prognosis of CPSS in dogs and cats. Attenuation of the CPSS is the treatment of choice and may be performed by open surgical intervention using ameroid ring constrictors, thin film banding, and partial or complete suture ligation or by percutaneous transvenous coil embolization. There is no strong evidence to recommend one surgical technique over another. Medical treatment strategies include administration of non-absorbable disaccharides (i.e., lactulose), antibiotics, and dietary changes, and are indicated for pre-surgical stabilization or when surgical intervention is not feasible. After CPSS attenuation, short- and long-term post-surgical complications may be seen, such as post-operative seizures and recurrence of clinical signs, respectively. Prognosis after surgical attenuation of CPSS is generally favorable for dogs and fair for cats.

Surgical treatment and outcome of intrahepatic shunts in 12 cats

CASE SERIES SUMMARY

The objective of this case series was to describe the presentation, surgical treatment and outcome of a congenital intrahepatic portosystemic shunt (IHPSS) in 12 cats. A retrospective case series of cats undergoing surgical treatment for an IHPSS was undertaken. Signalment, clinical signs, imaging, surgical treatment, complications and short-term outcome (<30 days) were obtained using medical records. Long-term outcome (>1 year after first surgery) was obtained, where possible, using a health-related quality of life owner questionnaire. Seven cats were diagnosed with a left divisional shunt, three with a central divisional shunt and two with a right divisional shunt using intraoperative mesenteric portovenography. Three cats tolerated 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 post-attenuation neurological signs (PANS) after first surgery and two cats (17%) died or were euthanased due to severe PANS. Long-term outcome was available for eight cats (67%), with a median follow-up time of 1743 days (range 364-2228), and was described as excellent in five cats (63%), fair in two cats (25%) and poor in one cat (12%).

RELEVANCE AND NOVEL INFORMATION

Few papers exist that describe the presentation, intraoperative imaging, treatment and outcome of IHPSSs in cats. This is the first to describe surgical attenuation with a thin film band in a cat with an IHPSS. This case series reports excellent long-term outcomes in a majority of surgically treated cats with IHPSS.

The effectiveness of intraoperative mesenteric portography for preventing misdiagnosis of congenital absence of the portal vein in dog with extrahepatic portosystemic shunt: a case report

A 5-month-old mixed-breed dog and a 10-month-old Welsh corgi dog were presented for evaluation with signs of congenital portosystemic shunt. In both dogs, computed tomography angiography revealed a single extrahepatic portosystemic shunt with the absence of the portal vein cranial to the shunt origin. Intraoperative mesenteric portography (IOMP) was performed after temporary complete occlusion of the shunt, revealing the portal branches faintly opacified with contrast medium. A cellophane band was applied around the shunt vessel without intraoperative attenuation. Postoperatively, both the dogs showed significant clinical improvement and the portal veins, not observed on preoperative ultrasonography, were visualized on postoperative ultrasonography. This study suggests the efficacy of IOMP, enabling the appropriate surgical procedure to be determined.

Use of percutaneous transvenous coil embolization in the treatment of intrahepatic portosystemic shunts in four cats

CASE DESCRIPTION

4 cats (6 to 9 months old) were evaluated because of clinical signs consistent with a portosystemic shunt (PSS).

CLINICAL FINDINGS

Among the 4 cats, 3 had neurologic abnormalities including ataxia, head pressing, disorientation, and obtundation. One cat was evaluated because of urethral obstruction; a retrieved urethral stone was determined to have urate composition. Clinicopathologic findings (hypoproteinemia, low BUN concentration, and high serum bile acids concentration) were consistent with a PSS in all cats. A diagnosis of intrahepatic PSS (IHPSS) was made for all cats on the basis of ultrasonographic and CT findings.

TREATMENT AND OUTCOME

All cats underwent percutaneous transvenous coil embolization (PTCE). No major intraprocedural complications were encountered, and all cats were discharged from the hospital. For the 3 cats that were presented with neurologic signs, an evaluation performed at 12, 14, or 48 months after the procedure revealed resolution of the neurologic signs, and owners reported that the behavior of each cat appeared normal. One cat that initially had neurologic and gastrointestinal signs had lower urinary tract signs after PTCE and developed an acquired extrahepatic PSS.

CLINICAL RELEVANCE

Although IHPSSs in cats are uncommon, the outcomes of PTCE for the 4 cats of the present report suggested that this treatment may benefit cats with an IHPSS. No short-term complications were encountered, and all cats had improvement in clinical signs following PTCE, although an acquired extrahepatic PSS was later identified in 1 cat. Further investigation of the use of endovascular techniques for the treatment of IHPSSs in cats and other species is warranted.

Astrocyte lesions in cerebral cortex and cerebellum of dogs with congenital ortosystemic shunting

Background

Congenital portosystemic shunt (cPSS) is one of the most common congenital disorders diagnosed in dogs. Hepatic encephalopathy (HE) is a frequent complication in dogs with a cPSS and is a major cause of morbidity and mortality. Despite HE been a major cause of morbidity in dogs with a cPSS, little is known about the cellular changes that occur in the central nervous system of dogs with a cPSS.

Objectives

The objective of this study was to characterise the histological changes in the cerebral cortex and cerebellum of dogs with cPSS with particular emphasis on astrocyte morphology.

Methods

Eight dogs with a confirmed cPSS were included in the study.

Results

Six dogs had substantial numbers of Alzheimer type II astrocytes and all cases had increased immunoreactivity for glial fibrillary acidic protein in the cerebral cortex, even if there were minimal other morphological changes.

Conclusions

This study demonstrates that dogs with a cPSS have marked cellular changes in the cerebral cortex and cerebellum. The cellular changes that occur in the cerebral cortex and cerebellum of dogs with spontaneously arising HE are similar to changes which occur in humans with HE, further validating dogs with a cPSS as a good model for human HE.

Canine intrahepatic portosystemic shunt insertion into the systemic circulation is commonly through primary hepatic veins as assessed with CT angiography

Congenital intrahepatic portosystemic shunts (IHPSS) in dogs are traditionally classified as right, left, or central divisional. There are few descriptive studies regarding the variation of IHPSS within these categories. This multicenter, analytical, cross-sectional study aimed to describe a large series of dogs with CT angiography (CTA) of IHPSS, hypothesizing that there would be variation to the existing classification. Ninety CTA studies were assessed for IHPSS type, insertion, and the relationship of the insertion to the primary hepatic veins. Ninety-two percent of IHPSS inserted into a primary hepatic vein (HV) or phrenic vein, 8% inserted directly into the ventral aspect of the intrahepatic caudal vena cava. The most common IHPSS type was a single right divisional (44%), including those inserting via the right lateral HV or the caudate HV. Left divisional IHPSS (33%) inserted into the left HV or left phrenic vein. Central divisional IHPSS (13%) inserted into the quadrate HV, central HV, dorsal right medial HV, or directly into the ventral aspect of the intrahepatic caudal vena cava. Multiple sites of insertion were seen in 9% of dogs. Within left, central, and right divisional types, further subclassifications can therefore commonly be defined based on the hepatic veins with which the shunting vessel communicates. Relating IHPSS morphology to the receiving primary HV could make IHPSS categorization more consistent and may influence the type and method of IHPSS attenuation recommended.

Treatment of congenital extrahepatic portosystemic shunts in dogs: A systematic review and meta-analysis

Background

Several options have been proposed for the treatment of congenital extrahepatic portosystemic shunts (cEHPSS) in dogs, but formal comparisons among different treatment options are currently unavailable. A previous evidence‐based review (2012) found low quality of evidence for papers assessing the treatment of cEHPSS in dogs.

Objectives

To assess the quality of evidence available in the treatment of cEHPSS, summarize the current state of knowledge with respect to outcome after cEHPSS management, and compare different treatment techniques.

Animals

Not used.

Methods

A bibliographic search was performed without date or language restrictions. Studies were assessed for quality of evidence (study design, study group sizes, subject enrollment quality, and overall risk of bias) and outcome measures reported (perioperative outcome, clinical outcome, and surgical or interventional outcome), all reported with 95% confidence intervals. A network meta‐analysis was performed.

Results

Forty‐eight studies were included. Six retrospective studies (grade 4b) compared 2 techniques and 7 were abstracts (grade 5). The quality of evidence was low and risk of bias high. Regarding surgical outcome, statistically significant superiority of ameroid constrictor over thin film band was observed (P = .003). No other comparisons were statistically significant.

Conclusions and Clinical Importance

The evidence base of choice of treatment of cEHPSS in dogs remains weak despite recent publications on the subject. Ameroid is superior to thin film band in causing EHPSS closure. Blinded randomized studies comparing different treatment modalities, which routinely include postoperative imaging to assess cEHPSS closure and acquired portosystemic shunt development are essential.

Feasibility of complete surgical ligation on 72 dogs with singular extrahepatic congenital portosystemic shunt based on portal pressure and comparison of intraoperative mesenteric portovenography

The relation between complete or partial ligation of extrahepatic portosystemic shunting and intraoperative mesenteric portovenography (IMP) was evaluated in 72 canines. Of the 72 dogs, 55 had complete ligation and 17 underwent partial ligation of abnormal vessels. IMP allowed evaluation of the number of intrahepatic portal branches and ratio of the diameter of cranial (CrPV) and caudal main portal vein (CaPV) at the shunt location. Nearly all cases in the complete ligation group and nearly half of the cases in the partial ligation group had three or more portal vein branches. CrPV/CaPV was 0.75 ± 0.24 in the complete ligation group and 0.29 ± 0.15 in the partial ligation group. CrPV/CaPV can be an effective new method for assessing IMP.

Survey of surgical specialists' content preferences in radiology reports for extrahepatic portosystemic shunts

The aim of this prospective, survey study was to assess the opinions of specialist surgeons as to the preferred content, nomenclature, and classification of extrahepatic portosystemic shunts for inclusion in radiology reports. A link to an online survey was sent by email to members of the European College of Veterinary Surgeons and the Association of Veterinary Soft Tissue Surgeons, and was made available on the American College of Veterinary Surgeons web forum and Facebook page. There were 93 respondents (survey sent to over 2500 email addresses and made available in two online locations). Most respondents agreed that they both review the images themselves (87/92, 95%) and read the radiology report (82/92, 89%) prior to surgery. Most respondents believed that the radiology report should contain a detailed anatomic description of the insertion (83/92, 90%), origin (54/91, 59%), and course (70/92, 76%) of the shunt, as well as a measure of the diameter of the shunting vessel at its insertion (54/92, 59%). Most respondents (70/90, 78%) disagreed that a brief description of shunt type, such as portocaval or portophrenic, was sufficient. Respondents were undecided regarding the use of an alphanumeric classification system (36/92, 39% agree; 32/92, 35% disagree). There was agreement that details of the presence or absence of urolithiasis (91/93, 98%), renomegaly (54/93, 58%), and peritoneal fluid (72/92, 78%) should be included in the report. The results of this study will help to guide reporting radiologists in providing descriptions of extrahepatic portosystemic shunts that include information most preferred by the recipient surgeons.

Interventional Radiology Management of Vascular Malformations: Portosystemic Shunts and Vascular Fistulae/Malformations

Vascular malformations are abnormal connections between blood vessels that can have various endothelial characteristics. Although uncommon, these malformations can present challenging diagnostic and therapeutic scenarios. The use of interventional radiology techniques in the management of various vascular malformations is an attractive option because of the ability to treat these malformations at the most appropriate anatomic location and in the most effective manner. Techniques such as coil embolization of intrahepatic portosystemic shunts and liquid embolization of arteriovenous fistulae/malformations have shown tremendous potential as treatments for these challenging diseases.

Congenital Extrahepatic Abdominal Arteriovenous Fistula and Apparent Patent Ductus Venosus in a Dog

A 3 mo old male German shepherd dog presented with a 2 wk history of diarrhea with possible melena followed by inappetence and progressive abdominal distension. Clinical findings, serum biochemical analysis, and abdominal ultrasound were highly suggestive of an extrahepatic abdominal arteriovenous fistula and concurrent patent ductus venosus, which were confirmed during an abdominal exploratory surgery. Renal biopsies taken at the time of surgery confirmed a chronic glomerulopathy. The dog made a good initial recovery from the procedure but was euthanatized 6 wk postoperatively for medically unresponsive renal disease.

Hyperammonemia and systemic inflammatory response syndrome predicts presence of hepatic encephalopathy in dogs with congenital portosystemic shunts

Hepatic encephalopathy (HE) is an important cause of morbidity and mortality in patients with liver disease. The pathogenesis of he is incompletely understood although ammonia and inflammatory cytokines have been implicated as key mediators. To facilitate further mechanistic understanding of the pathogenesis of HE, a large number of animal models have been developed which often involve the surgical creation of an anastomosis between the hepatic portal vein and the caudal vena cava. One of the most common congenital abnormalities in dogs is a congenital portosystemic shunt (cpss), which closely mimics these surgical experimental models of HE. Dogs with a cPSS often have clinical signs which mimic clinical signs observed in humans with HE. Our hypothesis is that the pathogenesis of HE in dogs with a cPSS is similar to humans with HE. The aim of the study was to measure a range of clinical, haematological and biochemical parameters, which have been linked to the development of HE in humans, in dogs with a cPSS and a known HE grade. One hundred and twenty dogs with a cPSS were included in the study and multiple regression analysis of clinical, haematological and biochemical variables revealed that plasma ammonia concentrations and systemic inflammatory response syndrome scores predicted the presence of HE. Our findings further support the notion that the pathogenesis of canine and human HE share many similarities and indicate that dogs with cPSS may be an informative spontaneous model of human HE. Further investigations on dogs with cPSS may allow studies on HE to be undertaken without creating surgical models of HE thereby allowing the number of large animals used in animal experimentation to be reduced.

Congenital portosystemic shunts in cats: investigation, diagnosis and stabilisation

PRACTICAL RELEVANCE

Although a relatively uncommon condition, the investigation, diagnosis and initial medical management of feline congenital portosystemic shunts is often undertaken within general practice. Early recognition and appropriate treatment are important to ensure a good outcome.

CLINICAL CHALLENGES

Clinical signs associated with CPSSs in cats are extremely variable and can be intermittent. Signs can affect a variety of organ systems including the nervous system, and gastrointestinal and urinary tracts. Thus, the differential diagnosis list may be very long and a CPSS may not be suspected initially. More specific diagnostic tests and diagnostic imaging are indicated but may not be 100% accurate and may not be readily available to the general practitioner.

AUDIENCE

This review highlights challenging aspects of the investigation and management of CPSSs for the practising veterinarian, but is also relevant to postgraduate students and provides a practical summary for specialists.

PATIENT GROUP

In practice, domestic shorthairs make up the majority of cats with CPSSs. However, Siamese, Persian and Himalayan cats may be more commonly affected than other purebreeds. While cats with CPSSs are typically under 6 months old, the condition is seen in mature animals, which may not have exhibited clinical signs for months or years.

EVIDENCE BASE

Despite several retrospective studies of cats with CPSSs, the evidence base for management of the condition remains limited.

Congenital portosystemic shunts in cats: surgical management and prognosis

PRACTICAL RELEVANCE

Although the surgical management of feline congenital portosystemic shunts (CPSSs) is normally performed at specialist centres, a good knowledge of treatment options and prognosis is important for the general practitioner when advising clients.

CLINICAL CHALLENGES

A variety of surgical techniques are described for the correction of CPSSs in cats. Choosing between the different techniques is a challenge, given the limited availability of evidence supporting one technique over another. In addition, postoperative complications, and in particular neurological complications, are seen more frequently in the cat than the dog and thus postoperative monitoring and treatment is critically important in feline patients.

AUDIENCE

This article summarises current evidence in surgical management and is aimed at practising veterinarians, postgraduate students and specialists alike.

EQUIPMENT

Surgical management of CPSSs typically requires advanced surgical and critical care facilities. The precise nature will depend to some extent on the technique employed.

EVIDENCE BASE

The evidence base for decision making in the surgical management of CPSSs is relatively sparse. In reviewing the evidence that is available, as well as the areas in which information is still lacking, this article may hopefully serve as a stimulus for further investigation into this condition.

Intravascular occlusion for the correction of extrahepatic portosystemic shunts in dogs

BACKGROUND

Congential extrahepatic portosystemic shunts (EHPSS) are common in dogs. An effective minimally invasive technique for correction of EHPSS could result in reduced morbidity, reduced costs, and reduced hospitalization times.

HYPOTHESIS

Use of an intravascular occlusion device can effectively and safely result in acute complete occlusion of EHPSS in dogs.

ANIMALS

Seven dogs with naturally occurring EHPSS that presented to the Purdue University Veterinary Teaching Hospital.

METHODS

Prospective, clinical trial. The 7 dogs were consecutively enrolled over a 2-year period. Results of serum biochemistry, total serum bile acids, fasting plasma ammonia, abdominal radiography, and ultrasonography suggested the diagnosis of portosystemic shunts in all dogs. Definitive diagnosis of EHPSS was achieved with cranial mesenteric arterial portography and acute occlusion was attempted by the deployment of the Amplatzer vascular plug (AVP).

RESULTS

EHPSS were identified in all dogs consisting of 5 portocaval and 2 portoazygous variants; 1/7 dogs (14%) were intolerant to temporary complete occlusion of the EHPSS. Of the remaining 6 dogs, 5 (83%) had complete occlusion of the EHPSS by the AVP. There were no complications and resolution of abnormal clinical signs and laboratory values was achieved in 4/5 (80%) dogs with complete occlusion.

CONCLUSIONS AND CLINICAL IMPORTANCE

Intravascular correction of EHPSS by the AVP is a viable option to surgical correction while larger studies will be required to determine the clinical applicability of this procedure in the broader portosystemic shunt population.

Plasma lactate concentrations and blood gas values in dogs undergoing surgical attenuation of a single congenital portosystemic shunt

Plasma concentration of lactate and the values of pH, pO(2) and pCO(2) were measured in the portal, systemic venous and, when possible, systemic arterial blood of 31 dogs with a single congenital portosystemic shunt, before and shortly after the temporary complete occlusion of the shunt, and at the end of surgery. At completion of the surgery, the shunt in 16 of the dogs had been occluded completely whereas in the other 15 it had been occluded only partially. There were no significant differences between any of the measurements of these variables in the portal venous, systemic venous or arterial plasma of any of the dogs, or between the values measured in the groups in which the shunts had been occluded completely or partially. Furthermore, there were no significant differences between the two groups of dogs in the arteriovenous gradients calculated at any of the sampling sites or sampling times. None of the variables was associated with the development of postoperative complications.

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.