Download PSS – PortoSystemic Shunts Introduction Introduction Portal vein

9/17/2013
PSS – PortoSystemic Shunts
Introduction
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Anomalous connection between the portal
and systemic venous systems
James Y Kim DVM,
DACVS
Providing the best quality care and
service for the patient, the client, and
the referring veterinarian.
Introduction
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Bypass of the liver
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Normal in utero
(ductus venosus)
Abnormal
postpartum
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Patent ductus
venosus
Intrahepatic
Extrahepatic
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Single
Multiple
Portal vein hypoplasia –
Microvascular dysplasia
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Abnormal hepatic bloodflow
Histopathologic finding
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Communication between
portal & systemic circulation
at microvascular level
Occur concurrently w/ PSS
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Small intrahepatic portal
vessels
58% of dogs & 87% of cats
PVH-MVD alone have
similar signs to PSS
Cairn & Yorkshire Terriers
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Liver physiology
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Protein metabolism
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Albumin
Coagulation proteins
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Gluconeogenesis
Glycogenolysis
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Bile acids
Cholesterol production
Neurologic
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Lethargy, ataxia,
obtundation, pacing,
circling, blindness,
seizures, coma
Gastrointestinal
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Vomiting, diarrhea,
anorexia, pica,
melena,
hematemesis
Extrahepatic
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Small/toy breeds
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Vitamins
Fats
Glycogen
Trace minerals
Clinical signs
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Kupffer cells
Toxic metabolites
Bacterial endotoxins
Drug metabolism
Storage
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Fat metabolism
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Immune/Clearance
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Carbohydrate
metabolism
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Signalment
Intrahepatic
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Yorkies
Maltese
Havanese
Pugs
Terriers
Large breeds
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Irish Wolfhounds
Retrievers (labs &
goldens)
Australian cattle dogs
Australian shepherds
Cats
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DSH, Persians,
Siamese, Himalayans,
& Burmese
Hepatic Encephalopathy (HE)
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Urinary
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Hematuria,
stranguria,
pollakiuria, urethral
obstruction
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Pathophysiology
largely unknown &
complex
>20 compounds in
excess w/ PSS
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Ammonia, aromatic AAs,
benzodiazepines, GABA,
glutamine, short chain
FAs, tryptophan
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Ammonia
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Excitotoxic
↑glutamate
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Excitatory
neurotransmitter
Chronicity leads to ↑
to inhibitory factors
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GABA
Endogenous
benzodiazepines
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Diagnostics
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Complete blood count
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Diagnostics
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Microcytosis
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+/- normochromic, nonregenerative anemia
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Target cells
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Poikilocytes
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Leukocytosis
Serum chemistry
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associated with a poor prognosis
Diagnostics
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Urinalysis
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Hyposthenuria to isosthenuria
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Diagnostics
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Bile acids
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Hepatic encephalopathy (psychogenic PD)
Poor renal medullary gradient (decreased BUN)
Crystaluria
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Ammonium biurates
Glomerular sclerosis secondary to antigen exposure
Paired samples
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12 hour fasting
2 hour postprandial
Normal values
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Proteinuria
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Hypoalbuminemia
Reduced BUN
Hypocholesterolemia
Hypoglycemia
Fasting 1.7 ± 0.3µM
Postprandial 8.3 ± 2.2µM
Some normal Maltese dogs
have increased serum bile
acids
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Diagnostics
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Baseline Ammonia
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Abnormal in 62-88% of animals w/ PSS
Ammonia tolerance test (ATT)
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Administration of ammonium chloride per os or
per rectum
Samples taken at prior administration & 30
minutes post
Contra-indicated in animals exhibiting HE
Imaging Diagnostics
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Nuclear Scintigraphy
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Great screening tool
Highly sensitive
Noninvasive, requiring
no anesthesia
Technetium
pertechnetate
Protein C
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Vit K dependent serine protease enzyme
Test to differentiate PSS from PVH-MVD
Normal >70%
PSS < 70%
PVH-MVD >70%
Imaging Diagnostics
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Transcolonic
scintigraphy
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Isotope infused per
rectum into the colon
Radioactivity is
visualized sooner
and in higher
concentration at the
heart
Liver
Heart
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Imaging Diagnostics
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Transplenic
scintigraphy
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Sedation required
Ultrasound guided
injection
Identify location and
number of shunts
Imaging Diagnostics
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Abdominal
Ultrasound
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Highly operator
dependent
Sensitivity and specificity
increases with sedated
or anesthetized patients
Findings
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Morandi F, Cole RC, Tobias KM, et al. Use of 99mTcO4 transplenic portal scintigraphy for diagnosis of portosystemic
shunts in 28 Dogs. Vet Radiol Ultrasound 2005;46:153–161.
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Shunting vessel
Microhepatica
Renomegaly
Cystic calculi
Imaging Diagnostics
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Computed
Tomographic
Angiography
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Gold standard in
human medicine
Dual-phase CT
angiography
superior
Identify non-surgical
PSSs
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Other Imaging Diagnostics
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Portovenography
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Antibiotics
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Treat bacteremia
Decrease bacterial
ammonia production
Metronidazole
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Ampicillin
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Neomycin
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7.5mg/kg
22mg/kg
22mg/kg
MRI
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85% in dorsal
91% in right lateral
100% in left lateral
Medical treatment
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Performed during
laparotomy w/
fluoroscopy
Injection into splenic or
jejunal vein w/ iohexol
Sensitivity
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Other Imaging Diagnostics
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Extended
anesthesia
Cost prohibitive
CT provides superior
detail
CT is extremely
quick w/ multi-sliced
scanners
Medical treatment
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Lactulose
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Convert ammonia
(NH3) to ammonium
(NH4+)
Decrease intestinal
transit time
0.5-1.0 ml/kg PO q
6-8hrs
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Medical treatment
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Gastroprotectants
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Sucralfate
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Loading 16mg/kg divided over 4 doses during a 12-24hr
period
Maintenance 2-4mg/kg PO divided into 2-3 doses/day
Potassium bromide
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Loading 400-600mg/kg divided over 1-5 days
Maintenance 20-30mg/kg/day
Keppra(levetiracetam)
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40mg/kg
Protein-restricted
diet
20mg/kg PO q 8hrs
Fryer KJ, Levine JM, Peycke LE, Thompson JA, Cohen ND. Incidence of postoperative seizures with and without
levetiracetam pretreatment in dogs undergoing portosystemic shunt attenuation. J Vet Intern Med. 2011 NovDec;25(6):1379-84.
Medical treatment
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Hepatosupport
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SAMe
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Ursodeoxycholic acid
(ursodiol)
18-22% dogs
30-35% cats
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Vit E
Dairy & vegetable
protein sources
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Milk thistle (silymarin)
Moderate protein
restriction
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2-3µg/kg
Medical treatment
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1.0-2.0mg/kg
Misoprostol
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Phenobarbital
0.5-1.0mg/kg
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Anti-convulsants
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Omeprazole
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Gastrointestinal ulcerations
Famotidine
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Medical treatment
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17-22mg/kg/d
10-15mg/kg/d
15 IU/kg/d
8-20mg/kg divided q
8hrs
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Medical treatment outcomes
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Long term survival1
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51.9% for medically treated patients
87.9% for surgically treated patients
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Did not affect survival
Intrahepatic vs
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Poor prognostic
indcators
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Age1
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Predictors of outcome
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Extrahepatic2
64.7% vs 33% were euthanized due to
uncontrolled signs
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1Greenhalgh
SN, Dunning MD, McKinley TJ, Goodfellow MR, Kelman KR, Freitag T, O'Neill EJ, Hall EJ, Watson
PJ, Jeffery ND. Comparison of survival after surgical or medical treatment in dogs with a congenital portosystemic
shunt. J Am Vet Med Assoc. 2010 Jun 1;236(11):1215-20.
2Watson PJ, Herrtage ME. Medical management of congenital portosystemic shunts in 27 dogs--a retrospective
study. J Small Anim Pract. 1998 Feb;39(2):62-8.
Surgical treatment
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Suture ligation
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2-0 silk
Complete
attenuation
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Partial attenuation
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86% cannot tolerate
Low albumin
Anemia
Leukocytosis
Low body weight
(IHPSS)
Neurologic signs
(HE)
Surgical treatment
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Ameroid ring
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Ring of casein
surrounded by
stainless steel
Hygroscopic
substance that
swells after
absorbing fluid
Incites fibrous tissue
reaction
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Surgical treatment
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Cellophane banding
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Clear nonmedical
grade cellophane
1 x 10cm strips
folded into thirds
Hemoclips used to
secure the band
Fibrous tissue
reaction leading to
gradual occlusion
Surgical treatment
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Surgical video
Percutaneous transjugular
coil embolization
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Fluoroscopic guidance
Caval stent placed via
jugular vein
Embolization coils inserted
through a vascular catheter
Surgical treatment
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Liver biopsies
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Identify PVH-MVD
58% of canine cases
87% of feline cases
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Surgical complications
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Hypoglycemia
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Portal hypertension
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44% of cases
2-14% of cases usually
w/ suture ligation
Seizures
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3-18% dogs, 8-22% cats
w/in 80hrs post-op
Concurrent disease
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Recurrence
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Post-operative management
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Failure of attenuation
Second shunt
Development of multiple
extrahepatic shunts
PVH-MVD
Continued medical
management
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Antibiotics,
lactulose, protein
restricted diet
Recheck
technesium scan
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Recheck bloodwork
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@ 3 months
Bile acids
Albumin
BUN
@ 6 weeks
GME, hypoxia, epilepsy
Questions ?
Thank you!
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