Indications for construction of systemic to pulmonary artery shunt

1
Indications for construction of systemic to
pulmonary artery shunt

• A. Borghi
• Centro Diagnosi e Trattamento Cardiopatie
  Congenite
• A.O. Ospedali Riuniti - Bergamo

I.Re.F. Milano, 18/1/2007
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Definition

• A systemic to pulmonary artery shunt is a
  surgical palliation aimed to increase the
  pulmonary blood flow (QP) any time it is
  insufficient
• It consists in creating a novel communication
  between the systemic and pulmonary circulations,
  deviating some blood into the relativelly empty
  pulmonary vascular bed

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History

• The first shunt, a termino lateral anastomosis
  between the L subclavian artery and the L
  pulmonary branch, was performed in 1945, on a
  boy affected by Tetralogy of Fallot, after
  suggestion of Dr. H. Taussig, prompted by the
  experimental surgery on dogs performad in
  Philadelphia by A. Blalock

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History

• This was called the Blalock-Taussig shunt.
• Some years later other types of shunt were
  introduced, named after their inventor or
  promoter.
• Potts shunt (1946) creation of a calibrated
  latero-lateral anastomosis between the descending
  aorta and the L pulmonary branch.
• Waterston shunt (1962) creation of a calibrated
  latero-lateral anastomosis between the ascending
  aorta and the R pulmonary branch.

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History

• Continuing clinical experience demonstrated
  advanteges and disadvantages of various
  operations some of them have been gradually
  abandoned (Waterston, Potts) or underwent
  significative technical adjustements (modified
  Blalock Taussig 1976)
• Nowadays the only shunts currently performed are
  the modified Blalock-Taussig and the central
  shunt, according to the clinical setting.

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Indications

• Any situation in which pulmonary blood flow (QP)
  is inadequate to provide enough oxygen for the
  metabolic needs of the systemic circulation
• and
• surgical repair is impossible or controindicated
• or
• in classic Norwood I operation for HLHS

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Haemodynamic effects

• Increase the pulmonary blood flow ideally a
  QP/QS ? 1 should be achieved
• Increase the amount of saturated blood reaching
  the systemic circulation
• Improve oxygen delivery to organs
• Promote growing of pulmonary branches

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Which shunt?

• Waterston and Potts were abandoned because of
  immediate and late problems
• sizing of the anastomosis
• difficult closure at repair
• distortion of the pulmonary branch
• development of pulmonary hypertension

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Which shunt?

• Modified B-T (calibrated PTFE conduit between R/L
  subclavian artery and the homolateral pulmonary
  branch) is currently performed, unless
  unfavourable situations suggest classic B-T or
  central shunt (short calibrated PTFE conduit
  between aorta and main pulmonary artery)
• Age of the patient, type of malformation, local
  facilities can influence the decision making in
  the single patient

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Indications in candidates to biventricular
correction

• Tetralogy of Fallot
• DORV PS
• Fallot CAVC
• TGA VSD PS
• C-TGA VSD PS
• Complex malformations with balanced ventricles,
  PS
• Selected Ebstein anomaly

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Malformations with pulmonary stenosis

• In anomalies with pulmonary stenosis the
  pulmonary circulation is usually non-dependent
  from ductus patency or from native systemic to
  pulmonary artery collaterals (MAPCAs) and the
  need of a shunt may onset at any age
• The clinical conditions (O2 saturation, metabolic
  acidosis, anoxic spells, response to stress) and
  a precise diagnosis are the fundamental elements
  for a decision making
• Prenatal diagnosis can aid to anticipate the need
  for palliation and allow to a propes choice of
  site and modality of delivery

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Tetralogy of Fallot

• Tetralogy of Fallot was the first congenital
  heart disease to be palliated by S to P shunt
  and, due also to the relatively high incidence of
  the anomaly, the number of procedures increased
  very quickly in a few years

• Today the indications are more restrictive and
  primary repair is definitely preferred whenever
  possible

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Tetralogy of Fallot

• Severe hypoplasia of the pulmonary tree in
  neonates/small infants is a commonly accepted
  indication

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Tetralogy of Fallot

• In presence of anoxic spells in infants with
  moderate hypoplasia of the pulmonary tree, a
  shunt may be an option to postpone surgical repair

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DORVPS FallotCAVC

• For DORV PS the indications are likely the same
  as for Fallots tetralogy
• In Fallots tetralogy associated with CAVC shunt
  is performed relatively often, because the
  elective age of repair is usually higher than in
  the isolated malformation

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TGAVSDPS

• In TGAVSDPS a shunt is indicated when, in
  presence of a large ASD, cyanosis due to the
  LVOTO is severe and the patient is young for
  Rastelli repair

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C-TGAVSDPS

• In C-TGAVSDPS a shunt is indicated when
  cyanosis due to the LVOTO is severe and the
  patient is young physiologic or Rastelli repair
• Decision making is usually particularly
  difficult, due to the dynamic nature of the LVOTO

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Others

• Any complex malformation with balanced
  ventricles, severe PS, amenable to biventricular
  repair, can necessitate a shunt if corrective
  surgery is not yet indicated
• In very selected cases the shunt is an option in
  severe neonatal Ebsteins malformationPS

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Indications in candidates to biventricular
correction

• PA and VSD
• Selected PA intact septum
• TGA VSD PA
• C-TGA VSD PA
• Complex malformations with balanced ventricles
  PA

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Malformations with pulmonary atresia

• In anomalies with pulmonary atresia the pulmonary
  circulation is necessarily dependent from ductus
  patency or from native systemic to pulmonary
  artery collaterals (MAPCAs)
• In ductal dependent situations a shunt is
  mandatory for survival, unless a direct flow from
  the RV is restored, as in selected cases of PA
  intact septum
• In the presence of MAPCAs any single patient must
  be investigated for proper treatment

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PAVSD,confluent PAs

• Morphology of the pulmonary tree and presence or
  absence of MAPCAs care essential for the surgical
  policy

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PAVSD,confluent PAs
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PAVSD, non-confluent PAs, MAPCAs

• Number, dimensions, shape, vascular bed of
  MAPCAs, presence of PDA are the elements for
  surgical decisions

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PAVSD, non-confluent PAs, MAPCAs
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PA, intact septum

• In PA intact septum different therapeutic
  approach can be adopted, according to anatomy,
  local facilities, conditions of the patient

• Different possibilities include
• RF perforation of the valve and PTA, ? ductal
  stenting/shunt
• Shunt duct closure
• Shunt surgical valvotomy/PTA
• RVOT reconstruction ? shunt

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PA, intact septum

• Morphology and dimensions of RV, tricuspid valve,
  RVOT, are essential for the decision making

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Indications in candidates to Fontan type
circulation

• Tricuspid atresia (I A, I B)
• PA intact septum with hypoplastic RV
• Double inlet ventricles (any morphological type)
  with PS/PA
• Complex malformations with unbalanced ventricles,
  PS/PA
• HLHS

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Classification of Tricuspid Atresia
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Tricuspid Atresia IA/IB and II A/B
I B

• In TA with PA, regardless the position of the
  great arteries, a shunt is always indicated
• In TA with PS performing a shunt before the Glenn
  is not always necessary

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PA, IS, diminutive RV

• In absence of sinusoids shunt is a
  straightforward indication
• Coronary circulation dependence from the RV as a
  poor prognosis and the shunt, immediately
  life-saving, may worsen myocardial ischemia

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UVHs (any type) with PS/PA

• In univentricular hearts with PA, regardless the
  morphology and the position of the great
  arteries, a shunt is always indicated
• In univentricular hearts with PS performing a
  shunt before the Glenn is not always necessary

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Complex malformations with unbalanced ventricles,
PS/PA

• Complex spatial arrangiaments of ventricular mass
  are rare, but can occur, particularly in the
  context of isomeric sindrome
• Criss-cross and under-over ventricle are
  other examples
• When PA is present a shunt is mandatory
• With PS clinics will guide the indication

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HLHS

• In HLHS pulmonary blood flow is not reduced and
  the problem is rather the ductal dependence of
  the systemic circulation
• A systemic to pulmonary artery shunt is part of
  the classic Norwood I procedure, that is the
  therapeutic step in this malformation

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Indications in candidates to one and 1/2
circulation

• One and 1/2 definitive palliation is indicated in
  cases with PA intact septum with moderatly
  hypoplastic RV, non suitable to entirely sustain
  the pulmonary circulation
• A shunt is usually part of the treatment
  preferably on the RPA, is replaced by a Glenn
  anastomosis