Stent Implantation of the Arterial Duct in an Infant with Duct-Dependent Circulation

Ductus stenting is indicated mainly in duct-dependent cyanotic lesions where Blalock-Taussig shunt is indicated in simillar ground. Baby L was a 5 months old girl who had history of severe cyanosis and respiratory distress for about a week and immediate work up in paediatric cardiology unit of combined military hospital (CMH) Dhaka after admission reveiled critical pulmonary stenosis , intact ventricular septum and a small patent ductus arteriosus (PDA). She was taken into the catheterization laboratory on urgent basis and stenting of PDA done with a 3.5mm X 11mm coronary stent. Her oxygen saturation steps up to 90% following the procedure. Patient was discharged from hospital 72 hours after the procedure.

Introduction:

Use of surgical aortopulmonary shunt is well established for improving pulmonary blood flow in infants with a critical reduction in pulmonary blood flow 1. Recently stenting of the patent ductus arteriosus (PDA) has emerged as a safe alternative in some selected case of cyanotic heart disease with reduced pulmonary blood flow2. Unlike the patent ductus arteriosus as isolated or combined lesion in cyanotic heart diseases, the ductus in cyanotic lesions has a remarkable morphological variation. Ductus tends to arise more proximally under the aortic arch giving rise to a vertical ductus or may arise from other arch vessels. It also has anatomical variations and it may also insert in an abnormal area like branch pulmonary arteries with stenosis at the insertion site. Ductus Stenting may be done retrograde through the femoral artery or antegrade through the femoral venous approach depending on ductus anatomy. Acute stent thrombosis is a major complication which should be treated urgently by a thrombolytic agent and mechanical disruption of thrombus if required. Stent migration to pulmonary artery may occur which should be treated as a semi-urgent basis. The stent should be removed surgically. A carefully selected case in an experienced
hand provides reasonable short to medium term palliation in duct-dependent cyanotic heart disease.

Case History:

A 5 months old baby girl was admitted to Combined Military Hospital Dhaka on 14th September 2009 with
the complaints of a cough for 1 month and cyanosis since birth, On examination, she was found extremely
dyspnoeic. Her oxygen saturation was around 50%. Her chest X-ray showed cardiomegaly with enlarged
right atrium and oligaemic lungs. ECG of the baby showed right axis deviation and right bundle branch block.

Echocardiography with color doppler study showed critical pulmonary valve stenosis with very little forward flow of blood to the pulmonary artery. Moderate tricuspid regurgitation and large atrial septal defect (ASD) was noticed. A small patent ductus arteriosus (PDA) of 1.5mm size was also seen. Because of very low oxygen saturation, injection prostaglandin E1 was started but there was not that much improvement of the oxygen saturation as a baby was already 4 months old. She was taken into the catheterization laboratory of CMH Dhaka on next day for urgent pulmonary balloon valvuloplasty. But right ventricular angiography showed

completely atretic right ventricular outflow tract. Her aortogram showed a tiny PDA which was almost closed. So a decision was changed and PDA stenting was done as a life-saving measure.

Procedure:

Equipment required :

a. Guiding catheter 6F
b. Y connector
c. PTCA wire .014 × 180 cm (Galio-hydro M)
d. 3.5mm X 11mm Gazelle coronary balloon mounted stent.
e. Pediatric drape
f. Diagnostic trolly with puncture set and sheath.
g. Pigtail catheter 4f
h. Terumo guides wire 0.32 mm
i. Behrman balloon angiographic catheter

A patient was sedated with injection ketamine and injection midazolam. Diagnostic RV angiography and aortogram were performed.

A guiding catheter was engaged in the aortic end of PDA and PTCA wire was forwarded through the Y connector and catheter to the pulmonary artery. Balloon mounted stent was forwarded to PDA over the wire and balloon dilated 2/3 times after checking the position of the stent. Hand injection of dye showed the good positioning of the stent. Wire and balloon were withdrawn slowly. The guiding catheter was taken out and aortogram repeated with a multipurpose catheter. Good flow through PDA noticed.

All lines removed and hemostasis ensured. The patient was on heparin infusion for next 48 hours (15u/kg/hr). Aspirin tablet was added from 2nd day.

A patient was discharged from the hospital 72 hours after the procedure.

Discussion:

Patent ductus arteriosus stenting has been proposed as an alternative to surgical shunt on account of postoperative morbidity and complication of surgical shunting 3. For a patient with the only ductal pulmonary flow, PDA stenting is an effective transcatheter approach to improve pulmonary circulation.

Initial results and medium term follow up of stent implantation of PDA in duct-dependent pulmonary circulation was studied in National Heart Institute of Malaysia and concluded that PDA stenting is an attractive alternative to surgical shunt in a majority of duct dependent circulation.

Another study was conducted in Istambul, Turkey where the efficacy and safety of stent implantation into stent inside PDA after balloon inflation  Aortogram showing large PDA with inflated stent inside Stent Implantation of the Arterial Duct in an Infant with Duct-Dependent Circulation the ductus arteriosus in infants with cyanotic heart disease was studied 7. A coronary stent was implanted in eight out of ten cases. All of them had adequate relief of cyanosis and was discharged home. This study recommends stenting as an effective alternative to surgical systemic-pulmonary artery shunt.

A study conducted in Hamburg University of Germany among 21 neonates where Palmaz stents were used
successfully in all cases and the medium-term result was found satisfactory.

Many other studies were conducted in other centers and overall survival rate up to six years was found 86 %.

After the Initial stenting, Fontan type operations are planned in some cases, few patients may require additional BT shunt even and some patient may need additional perforation of an atretic pulmonary valve or valvuloplasty.

Some of the patients have the risk of restenosis of the stent and therefore re-intervention. Re-stenosis is common in morphologically abnormal PDA. For the present case, Fontan type operation is planned. She already has passed 6 months follow up time and maintaining good oxygen saturation.

Conclusion:

The growth of pulmonary vascular bed after PDA stenting determines the type of surgery. In some patients even corrective surgery is possible, some patient goes for palliation and some patient can even be completely cured by intervention alone.

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