Ameroid Ring Constrictor Research Articles

Clinical outcomes for 20 cats with congenital extrahepatic portosystemic shunts treated with ameroid constrictor ring attenuation (2002-2020).

To report the clinical perioperative, short-term, and long-term outcomes for cats undergoing ameroid ring constrictor (ARC) attenuation of a congenital extrahepatic portosystemic shunt (EHPSS). Retrospective case series from a single veterinary teaching hospital (2002-2020). Twenty client-owned cats with EHPSS. Data collected from medical records included signalment, history, physical examination, clinicopathologic testing, medications, diagnostic imaging, intraoperative findings, perioperative complications, and postoperative clinical outcomes. Long-term clinical outcome was obtained from a standardized owner interview or medical records. Perioperative complications were reported in five cats out of 20, including blindness (two cats), ascites (one cat), head pressing (one cat), and seizures and death (one cat). Short-term clinical outcome was excellent in 14/18 cats, good in 2/18 cats, and poor in 2/18 cats that were available for follow up, and long term clinical outcome was excellent in 15/18, good in 1/18 cats, and poor in 2/18 cats that were available for follow up. Long-term clinical outcome was good or excellent in 16/18 of cats available for follow up. Perioperative complications were reported in five cats. Surgical attenuation of EHPSS with an ARC can result in resolution of clinical signs and biochemical abnormalities in the majority of cats. The perioperative complication rate for feline patients with EHPSS attenuated with an ARC was lower than reported historically. Seizures may persist in the long term despite normal bile acid stimulation test results, complete blood count, and biochemistry analysis.

External Self‐Closing Tube to Occlude a Vessel Gradually as a Therapeutic Means of Portosystemic Shunt

AbstractThe vascular network to the liver can be connected abnormally during fetal development (e.g., portosystemic shunt), thus requiring a device to close the flow connection completely. Gradual vascular occlusion is particularly important, because a sudden stop in blood flow can result in portal hypertension and cause consequential damage to the small intestine. Significant progress has been made in the development of such devices (e.g., the ameroid ring constrictor and cellophane banding) as a standard treatment for this disorder. However, incomplete occlusion is a common problem. In this study, a new vascular occlusion device is developed, enabling two major functions. First, user‐friendly deployment onto the external vascular wall is achieved by programming a recovery in the shape of the tube from open to closed in response to treatment with a warm saline solution (37 °C). Second, proinflammatory palmitic acid is released over time from the tube surface through the adventitial wall to induce gradual occlusive vascular remodeling. These unprecedented functions are demonstrated in a series of experiments on cells and rabbit veins, addressing this major issue through gradual but complete vascular occlusion over time. The external self‐closing tube represents a breakthrough proof‐of‐concept for treatment of this rare but critical developmental disorder.

Long-term clinical outcomes of dogs with single congenital extrahepatic portosystemic shunts attenuated with thin film banding or ameroid ring constrictors.

To compare long-term clinical outcomes of dogs with single congenital extrahepatic portosystemic shunts (CEHPSS) treated with thin film banding (TFB) consisting of polyolefin fiber or ameroid ring constrictor (ARC) placement in dogs. Retrospective, two-center clinical study. Client-owned dogs (n = 123) with single CEHPSS undergoing gradual attenuation via TFB (n = 85) or ARC (n = 38). Medical records of dogs with CEHPSS were reviewed. Follow-up data were collected from the referring veterinarian and/or owner via standardized questionnaire. Data were analyzed to compare short-term mortality rate and long-term outcome (>6 months). Dogs in the TFB group were older than dogs in the ARC group (median age, 19 vs 12 months, respectively; P = .01). There was no difference in survival to discharge between dogs in the TFB (81/85 [95.3%]) and ARC (37/38 [97.4%]; P > .99) groups. Preoperative levetiracetam was more frequently administered to dogs treated with TFB (64/85 [75.3%]) than to dogs treated with ARC (15/38 [39.5%;] P = .0002). Postoperative seizures were reported in 10 (8.1%) dogs; their prevalence did not differ between dogs treated with TFB (9/85 [10.6%]) and dogs treated with ARC (1/38 [2.6%]; P = .17). Median follow-up time for dogs treated with TFB (58.0 months, range 8-130) and ARC (63.3 months, range 7-138; P = .24) did not differ. Gradual attenuation of a single CEHPSS with either TFB or ARC resulted in similar long-term clinical outcomes and low postoperative morbidity and mortality rates. Thin film banding (polyolefin fiber) offers an alternative leading to clinical outcomes similar to ARC in dogs with single CEHPSS.

Outcomes of dogs treated for extrahepatic congenital portosystemic shunts with thin film banding or ameroid ring constrictor.

To compare the outcomes of dogs treated at a single institution for single extrahepatic congenital portosystemic shunts (CPSS) by thin film banding (TFB) or by placement of an ameroid constrictor (AC). Retrospective case series. Seventy-six client-owned dogs with CPSS treated with TFB (n = 53) or AC (n = 23). Records were reviewed for signalment, preoperative, intraoperative, and postoperative management and short-term outcomes. Data on second surgeries were reviewed. Long-term outcomes were obtained via an owner-directed health-related quality of life questionnaire. The rates of complications, mortality, and revision surgery were compared between the treatment groups. Postoperative complications occurred in 15 (28%) dogs with TFB (9% mortality, n = 5) and 8 (35%) dogs with an AC (4% mortality, n = 1). Long-term follow-up was available in 41 of 56 dogs at a median of 55 months (range, 15-89). Revision surgery for persistent shunting was performed in 14 (29%) dogs treated initially with TFB and in no dogs treated initially with AC (P = .007). Median long-term outcome scores were good in both groups; nine of 14 revision surgeries led to favorable outcomes. Persistent shunting requiring revision surgery was more common when CPSS were treated with TFB than with an AC, but both treatments achieved favorable long-term outcomes. Treatment of CPPS by placement of an AC rather than TFB seems more reliable for shunt attenuation and prevention of revision surgeries.

Comparative outcomes between ameroid ring constrictor and cellophane banding for treatment of single congenital extrahepatic portosystemic shunts in 49 dogs (1998-2012).

To compare outcomes and identify prognostic factors in dogs with single congenital extrahepatic portosystemic shunt (CEHPSS) gradually attenuated with an ameroid ring constrictor (ARC) or cellophane banding (CB). Retrospective, multi-institutional study. Forty-nine dogs with CEHPSS (n = 23 for ARC; n = 26 for CB). Medical records of dogs with CEHPSS treated by ARC or CB were reviewed for postoperative (<1 month), midterm (1-6 months), and long-term (> 6 months) outcomes. Data were evaluated to detect factors associated with postoperative complications, residual shunting, and long-term outcome. Postoperative complication rates did not differ between ARC (26.1%) and CB (23.1%, P = .89) and were negatively associated with body weight (P = .03). Overall, postoperative mortality was low (2.0%). Clinical long-term outcome was excellent in 45.0% and 39.1% and good in 55.0% and 60.9% of dogs after ARC and CB, respectively. Suspected residual shunting rate upon abdominal ultrasonography was greater after CB (31.6%) than after ARC (0%). ARC and CB were both effective for attenuation of CEHPSS, resulting in good to excellent outcomes with low morbidity and mortality. Residual shunting was suspected in a higher proportion of dogs treated with CB on the basis of abdominal ultrasonography results. However, further prospective randomized studies must be conducted with validated evaluation methods to verify this assumption.

Surgical correction of a splenophrenic shunt in a dog: a case report

A 4.3 kg, nine-year-old, spayed female Shih Tzu was presented for a two-month history of seizures, ataxia, and hyper-salivation. A diagnosis of a splenophrenic shunt was made by use of computed tomography angiography with volume-rendered imaging. A cellophane band was placed around the shunt after its isolation from the central tendon of the diaphragm. Clinical signs continued to wax and wane. Preprandial and postprandial bile acids levels were still elevated 10 months after surgery. An ameroid ring constrictor was placed around the shunt vessel before the vessel entered the diaphragm from its caudal aspect. At three months after the second surgery, the dog was near the normal ranges of preprandial and postprandial bile acids. Although a study of the anatomy of different types of extrahepatic portosystemic shunts has been reported in dogs, to the authors&amp;rsquo; knowledge, there is a lack of information on clinical presentation, treatment, and postoperative results in a specific type of extrahepatic portosystemic shunt, such as a splenophrenic shunt. Cellophane banding should be avoided for occlusion of a splenophrenic shunt passing along the central tendon of the diaphragm. &amp;nbsp;

Long‐term outcome after surgical ameroid ring constrictor placement for treatment of single extrahepatic portosystemic shunts in dogs

To report long-term clinical outcome in dogs treated for single congenital extrahepatic portosystemic shunt (CEHPSS) with a ameroid ring constrictor (ARC) and to identify perioperative variables associated with outcome. Retrospective, multi-institutional study. Dogs (n = 206) with CEHPSS. Medical records of dogs with CEHPSS treated by ARC were reviewed for perioperative and short-term (<1 month) data. Long-term follow-up information was obtained by telephone interview with referring veterinarians and/or owners. Kaplan-Meier analysis was used to estimate median survival time. Factors associated with short-term survival, outcome grade, and total survival time were identified. Fifteen dogs died <1 month after ARC placement. Follow-up data were obtained for 112 of 191 dogs that survived >1 month; median follow was 54 months (range, 1-175 months) and 103 (92%) dogs had no clinical signs. Estimated median survival time was 152 months. Variables significantly associated with short-term survival included being intact and a low total white blood cell (WBC) count. Variables significantly associated with a successful outcome included having surgery later in the study period and negative postoperative nuclear scintigraphy. In the long-term survival analyses, intact dogs and those with higher WBC counts and occlusion pressures and lower bile acid concentrations were more likely to survive. Dogs with CEHPSS treated by ARC generally have a good prognosis and prolonged postoperative survival.

Complications and long-term outcomes of the ligation of congenital portosystemic shunts in 49 cats

Only two of 49 cats undergoing surgical ligation of congenital extra- and intrahepatic portosystemic shunts died perioperatively, a mortality rate comparable with the mortality rates of dogs undergoing surgical attenuation...

Surgical Management of Left‐Divisional Intrahepatic Portosystemic Shunts: Outcome After Partial Ligation of, or Ameroid Ring Constrictor Placement on, the Left Hepatic Vein in Twenty‐Eight Dogs (1995–2005)

To evaluate outcome in dogs with left divisional intrahepatic portosystemic shunts (PSS) treated by partial ligation (PL) or ameroid ring constrictor (ARC) placement on the left hepatic vein. Retrospective study. Dogs (n=28) with left divisional intrahepatic PSS. Retrieved data from medical records of dogs with left divisional intrahepatic PSS that had PL (n=17) or ARC (n=11) were signalment, history, clinical signs, preoperative blood work, portal pressure measurements, ARC size, complications and postoperative technetium scintigraphy. Outcome assessed by owner interview 6 months-10 years after surgery was classified as excellent, good or poor. Differences were tested by exact chi2 test. Major complications occurred in 3 dogs: coagulopathy (1 PL dog died), ascites (1 PL dog survived) and seizures (1 ARC dog died). Eight PL dogs had technetium portal scintigraphy; 1 dog was negative and 7 dogs positive for persistent shunting. Seven ARC dogs had scintigraphy; 4 dogs were negative and 3 positive for persistent shunting. In PL dogs, long-term clinical outcome was excellent (92%) or good (8%) whereas, in ARC dogs it was excellent (20%), good (50%) or poor (30%). This outcome difference between treatment groups was significant (P=.0012). Dogs treated by PL had significantly better long-term outcome compared with ARC treated dogs. Based on these data, ARC placement on the left hepatic vein in dogs with left-divisional intrahepatic PSS cannot be recommended.

Evaluation of ameroid ring constrictors for treatment for single extrahepatic portosystemic shunts in dogs: 168 cases (1995–2001)

To evaluate use of an ameroid ring constrictor (ARC) for treatment for single extrahepatic portosystemic shunts (PSSs) and identify factors associated with postoperative death, continued portosystemic shunting, and long-term outcome in dogs. Retrospective study. 168 dogs with a single extrahepatic PSS. Medical records of dogs that had a single extrahepatic PSS and were treated with an ARC were reviewed. Signalment, history, clinical signs, results of preoperative blood analyses and portal pressure measurements, PSS location, ARC size, postoperative complications, and postoperative scintigraphy results were recorded. Owners were interviewed 6 months to 6 years after surgery. Results-Postoperative complications developed in 10% of dogs. Postoperative mortality rate was 7.1%. Predictive factors for postoperative death included high preoperative WBC count and postoperative complications. Twenty-one percent of dogs in which portal scintigraphy was performed 6 to 10 weeks after surgery had continued shunting. Predictive factors for persistent shunting included low preoperative plasma albumin concentration, high portal pressure after complete occlusion, and high portal pressure difference (postocclusion minus baseline). Clinical outcome in 108 dogs was classified as excellent (80%), good (14%), or poor (6%). Predictive factors for excellent long-term clinical outcome included high preoperative plasma albumin concentration, low preoperative leukocytosis, low portal pressure after complete occlusion, absence of postoperative seizures, and absence of continued shunting. Use of an ARC for treatment for a single extrahepatic PSS resulted in low morbidity and mortality rates. Certain preoperative factors were associated with increased risk of postoperative death, continued portosystemic shunting, and long-term outcome.

Evaluation of ameroid ring constrictors for the management of single extrahepatic portosystemic shunts in cats: 23 cases (1996–2001)

To document the signalment; history; clinical signs; clinicopathologic, diagnostic imaging, and surgical findings; perioperative complications; and long-term clinical results of ameroid ring constrictor (ARC) placement on single extrahepatic portosystemic shunts (PSS) in cats. Retrospective study. 23 cats treated with an ARC on a single extrahepatic PSS. An ARC was placed surgically around the PSS. Portal pressure was measured prior to ARC placement, with complete temporary PSS occlusion, and after ARC placement. Cats were scheduled for recheck transcolonic portal scintigraphy 8 to 10 weeks after surgery. Follow-up information was obtained by telephone interview with the owners. An ARC was successfully placed in 22 of 23 cats. Intraoperative complications, consisting of PSS hemorrhage, occurred in 2 cats. Mean (+/- SD) portal pressure (n = 15) was 6.7+/-2.9 mm Hg before PSS manipulation, 18.6+/-7.7 mm Hg with complete temporary PSS occlusion, and 6.9+/-2.7 mm Hg after ARC placement. Postoperative complications developed in 77% (17 of 22) of cats after ARC placement, and included central blindness, hyperthermia, frantic behavior, and generalized motor seizures. Perioperative mortality rate was 4.3% (1 of 23). Persistent shunting was identified in 8 of 14 cats. Overall, 75% (15 of 20) of cats had an excellent long-term outcome. Placement of an ARC on single extrahepatic PSS in cats resulted in low surgical complication and perioperative mortality rates, but most cats did have substantial postoperative complications. Persistent shunting was common, although many cats with persistent shunting were clinically normal.