abernathy and pulmonary av malformation

1. Pulmonary AV fistula in Abernethy
malformation

2. 8 year old boy..
 Recurrent minor hemoptysis
 SaO2 76 %
 Cyanosis,clubbing
 Clinically normal CVS
 ECG : SR, P normal, PR 120, QRS axis +90,no
chamber enlargement
 CXR

3.  Echo : No structural heart disease
 Anomalous channel draining into IVC,RA junction:
porto-systemic shunt
 Contrast Echo : Bubbles in LA after 3 cycles
 CT angio :
 Diffuse PAVM
 Patent ductus venosus
 Bunch of tiny, tortuous vessels surr left hilum,lower
esophagus with left bronchial artery supplying left hilar
vessles

4. Cath
 SVC 68 ; PA 63.5 ; Ao 80
 Post PA 73 ; Ao 86
 ABG : p H 7.36; p CO2 40.5; HCO3 22; SaO2 80.8
 Pressures :
 RA m 6
 RV 29 Ed 8
 PA 21/10 m 15
 LV 80 Ed10
 Ao 82/42 m 60

5. Cath
 Diffuse multiple PAVM seen B/L R>L
 Aortogram : 2 MAPCAs; left appeared to have AVM
distally
 Anomalous channel draining into IVC-RA jn

6. Pulmonary AV malformation
 Direct communications between branches of
pulmonary artery and pulmonary veins, without an
intervening pulmonary bed
 1897
 2–3 per 100 000 population
 male to female ratio varies from 1:1.5 to 1.8
 single (42% to 74%) or multiple (8-20%)

7. Pulmonary AV malformation
 Solitary PAVMs : left lower lobe most common >
right lower lobe > left upper lobe > right middle lobe
> right upper lobe
 Majority of multiple PAVMs : bilateral lower lobes
 Most commonly congenital (80%)
 47%–80% of congenital variety associated with
Osler-Weber-Render disease (HHT)
 5%–15% of HHT have PAVM

8. Embryology
 Defect in terminal arterial loops which allows
dilatation of thin walled capillary sacs
 Incomplete resorption of vascular septae that
separate arterial and venous plexuses which
normally anastomose during fetal development

9. PAVM
 Simple or complex.
 Simple : single feeding segmental artery and single
draining vein (80-90%)
 Complex : 2 or more feeding or draining vessels

10. PAVM
 Afferent supply  one or more branches of PA
 Sometimes systemic : aorta, intercostal and
bronchial arteries.
 Efferent limb : one or more branches of PV ;
sometimes directly into LA or IVC
 close proximity to the visceral pleura or outer third
of lung parenchyma

11. HHT
 PAVM in HHT : worse symptoms, multiple AVMs, rapid
disease progression, more complications
 consensus criteria of nosebleeds, mucocutaneous
telangiectasia, visceral AVMs and family history
 Chromosome 9 (9q 33–34 ) : endoglin
 Chromosome 12 (12q ) : activin receptor-like kinase 1
 Both bind TGF-b
 Endothelial cells respond abnormally to TGFb during
vascular remodeling AVM

12. Symptoms..
 Dyspnea most common : large or multiple PAVM
 Platypnea :secondary to decreased blood flow through PAVM in
dependent portions of lungs
 Hemoptysis
 Epistaxis : most common symptom in HHT : Precede
external telangiectases by 10 to 30 yr

13. Signs
 Triad of dyspnea, cyanosis, and clubbing (10%)
 Telangiectases
 Murmurs or bruits over the site of the PAVM
 Hypoxemia
 Orthodeoxia :decrease in Pa O2 or SaO2 when going from
recumbent to seated or upright position
 gravity induced increase in flow through basally
situated shunts (~ 70% of PAVMs)

15. CNS
 30%
 Paradoxic embolism across PAVM
 In situ thrombosis  polycythemia
 Coexisting cerebral AVM
 feeding arteries >3 mm in diameter

16. Complications..
 Hemoptysis :intrabronchial rupture of PAVM or
endobronchial telangiectasis,
 Haemothorax : rupture of subpleural PAVM.

17. Secondary or acquired PAVM
 chest trauma,thoracic surgery
 long standing hepatic cirrhosis
 metastatic carcinoma
 mitral stenosis :secondary to PAH
 infections (actinomycosis,schistosomiasis)
 systemic amyloidosis
 Pregnancy

18. Hepatopulmonary syndrome
 Failure of liver to clear circulating pulmonary vasodilators
 Production of circulating vasodilator
 Inhibition of circulating vasoconstrictor
 Inability of liver to metabolise various substances in portal
venous blood.
 Congenital hepatic fibrosis,portal vein thrombosis, non-
cirrhotic portal hypertension, congenital portovenous shunts
 PAVMs.
 PAVMS in palliated CHD

19.  Hepatic factor(s) (HF):
 protective role –physiologically present constrictor
influence.
 Portal venous factor(s) (PVF) :
 dilatory influences present in the portal venous blood :
substance P

20.  Plexogenic arteriopathy of cirrhosis medial
hypertrophy and fibrosis combined with dilated thin
walled distal channels,
 Constrictor and dilator influences on pulmonary
vasculature.

21. Abernethy malformation
 Type 1 : End-to-side mesocaval fistula, portal vein
terminates into IVC with no intrahepatic portal vein.
 more in women
 multiple congenital anomalies :CHD, duodenal and biliary
atresia, malrotation,annular pancreas, polysplenia, situs
inversus, anomalies of genitourinary and musculoskeletal
systems.
 Excessive involution of peri-intestinal vitelline venous
loop or total failure of vitelline veins to establish
anastomosis with hepatic sinusoids or umbilical veins

22. Abernethy
 Type 1a :SMV and splenic vein do not join to form
confluence
 Type 1b where the two veins join before entering systemic
circulation.
 Galactosemia, hypoglycemia, hyperammonemia,
encephalopathy
 Hepatic encephalopathy.
 shunt ratio > 60% may predict age of onset of hepatic
encephalopathy
 Liver transplantation

23. Abernethy..
 Type 2 : intact portal vein , some portal flow into
IVC via a side-to-side anastomosis.
 intrahepatic portal vein hypoplastic
 persistence of subcardinohepatic anastomosis with the
vitelline veins
 PAH in some
 Hepatopulmonary syndrome in others  PAVM
 Triad of liver disease, arterial hypoxemia, and
diffuse pulmonary vascular dilatation


24. Abernethy and PAH..
 CHD, Left Isomerism ,Corrected -TGA, SA-VSD , PAH –
pulmonary vascular disease
 Type 2 Abernethy
 plugging of portosystemic shunt.
 Follow-up on sildenafil :
 left-to-right shunting (2.16:1)
 Fall in PVR

25. Abernethy and PAH
 Hyperdynamic circulation due to shunt  high
shear stress on pulmonary endothelium  increase
in PVR
 Vasoactive mediators - serotonin, cytokines, growth
factors, histamine, estrogen, glucagon, and
endotoxin, normally metabolized in the liver 
vasoconstriction


26. Hemodynamics
 Cardiac output, cardiac index, PCWP, heart rate,
BP,ECG usually normal
 If minimal shunting  symptoms mild or absent.
 Right-to-left shunt > 20% : cyanosis, clubbing, and
polycythaemia

27. Pulmonary Hemodynamics
 PA pressure is normal or low : act as a low
resistance circuit.
 88 with PAVM: Mean PA pressure normal or low in
80 of 88
 8 with PAH : Mean 36 to 50 mm Hg
 Underlying chronic lung disease in 1
 Bilharzia in 1
 Chronic hypoxemia in 4
 PAH due to MS 1
 ?Idiopathic PAH 1

28.  ? Develop PAH secondary to chronic hypoxia
 No alveolar hypoxia :no hypoxic vasoconstriction

29. PAVM and PAH
 Most PAVMs have underlying HHT
 HHT carries independent risk of PAH
 1) Post-capillary PAH in high-output cardiac
failure secondary to hepatic AVMs with elevated
PAWP and normal or near-normal PVR
 2) True pulmonary arterial hypertension (PAH)
phenotype

30. PAVM and PAH
 Primary PAH : BMPR-II and ALK-1 mutations
(members of superfamily of TGF-b receptor)
 HHT : activin receptor-like kinase 1 (ALK-1) and
endoglin (ENG)
 Single-nucleotide polymorphism (SNP) in ALK1 gene
associated with HHT and PH.

31. Pulmonary hemodynamics
 New PAH or increase in baseline PAH following
embolization or resection of large PAVM

32. Diffuse PAVM..
 40% CNS complication
 Minor and major hemoptysis
 Symptomatic management if minor
 If major identification of origin of bleed
(bronchoscopy ; pulm angiogram)
 Coil occlusion if large PAVM ; surgery if massive
bleed and not amenable to percutaneous treatment
 Antibiotic prophylaxis to prevent brain abscess

33. 19 yr male
 Craniopharingioma –operated 2006 (on
replacement Thyroxine 150; Hydrocortisone 15)
 Recurrent epistaxis (endoscopy reportedly normal)
 Mild hemoptysis
 Cyanosis , FC II DOE
 Cyanosis+. Clubbing +
 SaO2 75-77% (ABG : p H 7.453; p CO2 30.3;
p O2 37.6; SaO2 72.1)

34.  Hb 20.5
 USG abd: borderline hepatomegaly with
fatty changes
 Echo : late appearance of contrast in LA
(after 3-4 cycles)

37. Treatment
 PAVMs enlarge
 Morbidity upto 50% in untreated patients
 3% in treated
 All symptomatic patients
 Feeding vessel >/= 3 mm

38. Treatment
 Surgery only treatment until 1978
 Taylor et al : percutaneous embolisation
 Currently preferred : percutaneous embolotherapy
using coils or balloons

39. Surgery
 Failed embolotherapy, serious bleeding complication
despite embolotherapy, intrapleural rupture of the PAVM,
untreatable contrast allergy and lesions not amenable to
embolotherapy.
 Local excision, segmental resection, lobectomy,
ligation,pneumonectomy

40. Our patient..
 Device closure of Abernethy malformation (12 mm
Amplatzer vascular plug)
 Coiling of right aorto-pulmonary collateral (two 035”-
2 mm – 30 mm platinum fibre coils)
 Left AP collateral could not be cannulated
 Diffuse PAVM : ? resolution following closure of
Abernethy malformation


41. Thank you