Br Heart3r 1993;70:474-475

Recanalisation of an occluded modifiedBlalock-Taussig shunt by balloon dilatation

Narayanswami Sreeram, Kevin Walsh, Ian Peart

Heart Clinic, RoyalLiverpool Children'sHospitalN SreeramK WalshI PeartCorrespondence to:Dr N Sreeram, Heart Clinic,Royal Liverpool Children'sHospital, Eaton Road,Liverpool L12 2AP.

AbstractA four year old boy with pulmonary

atresia and ventricular septal defect hadan acute cyanotic episode three years

after undergoing a right-sided, 6 mmdiameter, modified Blalock-Taussigshunt. On admission no continuous mur-mur could be heard from the shunt andthe typical high velocity, continuous flowprofile of the shunt could not be identi-fied by Doppler echocardiography. Atcatheterisation a right subclavian arteryangiogram confirmed shunt occlusion.From the subclavian artery, an 0 035inch wire was used to enter the occludedshunt and then the pulmonary artery.Balloon angioplasty of the entire lengthof the shunt was performed with 6 mmdiameter balloon. After angioplasty thearterial oxygen saturation increasedfrom 63% to 83%. The patient was

treated with intravenous heparin fol-lowed by warfarin. Repeat catheter-isation and angiography eight days laterconfirmed wide patency ofthe shunt.

(Br HeartJ 1993;70:474-475)

Figure 1 Right subclavian artery angiogram showing occlusion of the right sided

modified Blalock-Taussig shunt (arrow).

Modified Blalock-Taussig shunts with inter-position tube grafts between the subclavianartery and pulmonary artery are standardpalliative treatment for various cyanotic con-genital heart defects.' A major complicationis shunt occlusion, which often requiresemergency surgical revision.2 Transcatheterballoon dilatation of both occluded peripheralarteries and of stenosed (but not occluded)Blalock-Taussig shunts have been describedpreviously. We describe successful recanalisa-tion of an occluded modified Blalock-Taussigshunt in a child.

Case reportA four year old boy presented shortly afterbirth with moderate central cyanosis. A diag-nosis of pulmonary atresia with ventricularseptal defect, confluent central pulmonaryarteries, and multiple aortopulmonary collat-eral vessels was based on echocardiographyand cardiac catheterisation. At the age of 12months he underwent a right-sided modifiedBlalock-Taussig shunt (6 mm Gore-texgraft), after which he was treated with oralaspirin and dipyridamole at standard doses.He presented to his local hospital three yearslater with acute onset of cyanosis, associatedwith absence of a continuous murmur fromthe shunt. He was referred to our hospital.

At admission he had severe cyanosis with asystemic arterial oxygen saturation of 63%.Doppler echocardiography did not show thecontinuous high velocity flow profile associ-ated with the shunt. His parents gaveinformed consent and cardiac catheterisationwas performed the next day. A retrogradefemoral arterial approach was used to obtaina right subclavian artery angiogram with a 5FCobra (Cordis) catheter. This confirmedcomplete occlusion of the shunt (fig 1). An0035 inch stiff, angled hydrophilic wire (180cm, Terumo) was introduced into the shuntand advanced to the left pulmonary artery (fig2A), followed by the catheter. The wire wasexchanged for an 0'018 inch (175 cm) Ultra-Select nitinol guidewire (Microvena) with a4 cm angled flexible tip. A 6 mm diameterTyshak balloon (NuMed) was advanced intothe shunt over the wire and multiple infla-tions were performed along the length of theshunt. The arterial oxygen saturationincreased to 83%. Angiography showed a

widely patent shunt (fig 2B). Initially intra-venous heparin was given as anticoagulanttherapy and subsequently oral warfarin was

given. The patient was discharged from

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Recanalisation ofan occluded modified Blalock-Taussig shunt by balloon dilatation

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Figure 2 (A) Radiograph after introduction ofa wire through the occluded Blalock-Taussig shunt (arrow) and into the left pulmonary artery.(B) Angiogram after baloon dilatation of the shunt showing a widely patent shunt (arrows) fiUling both branch pulmonary arteries.

hospital 12 days later. Before discharge,repeat cardiac catheterisation and angiogra-phy confirmed that the shunt was patent.

DiscussionThe modified Blalock-Taussig shunt is thestandard palliative surgical treatment for vari-ous cyanotic heart lesions.' For complexlesions, further corrective surgical interven-tions may not be feasible, and prolongedpatency of the shunt is essential for long-termpalliation. However, interposition shuntsbetween the subclavian and pulmonary arteryare liable to become stenosed or occluded.2Transcatheter balloon dilatation of stenosedshunts has been proposed as an alternative tosurgical revision. Most have been performedfor stenosed classical Blalock-Taussig shunts,where direct end-to-side anastomosis of thesubclavian artery to the pulmonary artery hasbeen performed.?5 There is, however, awealth of experience with balloon dilatationand recanalisation of occluded peripheralarteries in adult patients." A major limitationin the application of this technique foroccluded systemic to pulmonary artery shuntsin children is that patients in whom the shuntwas the major (or singular) source of pul-monary blood flow often have severe hypoxiaand metabolic acidosis at presentation andtherefore require emergency surgical inter-vention. Prolonged attempts at transcatheter

recanalisation of the shunt are not withoutrisk in such situations. When other sources ofpulmonary blood flow in the form of aorto-pulmonary collateral arteries or a patent butstenosed pulmonary valve are present, how-ever, the patient is often in a stable haemo-dynamic state despite shunt occlusion. Insuch patients transcatheter balloon dilatationand recanalisation of a recently occludedshunt may have an important role.

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