midterm outcome of stent dilatation of patent ductus arteriosus in ductal-dependent pulmonary...

Midterm Outcome of Stent Dilatation of Patent Ductus Arteriosusin Ductal-dependent Pulmonary Circulation

Arif Hussain, MD, Salem Al-Zharani, MD, Amin Arfi Muhammed, FCPS, Jameel Al-Ata, MD, andOmar Mohammed Galal, MD, PhD, MBA

Section of Pediatric Cardiology, King Faisal Specialist Hospital and Research Center, Jeddah, Saudi Arabia

A B S T R A C T

Objective. We sought to assess the outcome of transcatheter ductus arteriosus stenting in newborns with ductal-dependent pulmonary circulation.Background. Better results of ductal stenting have been reported using stents with better scaffolding and ensuringstenting of the entire length of the ductus arteriosus.Methods. Twenty-one patients with ductal-dependent pulmonary circulation were brought to the catheterizationlaboratory for ductal stenting. Five patients did not qualify because of a complex tortuous ductus arteriosus or branchpulmonary artery stenosis. Stent implantation was successful in 14 patients. The duct was accessed with a 0.014-inchguidewire. A low profile premounted coronary stent was implanted in the duct without using a long delivery sheath.Attempts were made to cover the entire length of the ductus arteriosus.Results. The mean age of the patients at the time of stent implantation was 24 � 17.5 days. The mean body weightwas 2.9 � 0.35 kg. The ductus was mildly tortuous in four, moderately tortuous in four, conical in four, and verticalin four patients. Ductal stenting was successful in 14 patients. The mean ductal diameter was 3.9 � 0.5 mm. Themean diameter and the length of the stent implanted were 3.9 � 0.72 and 15.4 � 3.16 mm, respectively. Meanfluoroscopy and procedure times were 22.16 � 12.5 and 107.9 � 34.5 minutes, respectively. Out of the 14 successfulstent implantations, the ductus arteriosus was not completely covered with the stent in five patients at the time ofprimary procedure, four of them required re-stenting for significant desaturation. One of these patients died despitesuccessful re-stenting. Another patient died due to aspiration pneumonia. Of the 12 survivors, five underwent Glennshunt (two deaths related to pulmonary hypertension), two underwent biventricular repair, one patient was lost tofollow-up, and the remaining four are doing well with a mean oxygen saturation of 85% at a mean follow-up of13 � 6 months.Conclusion. Stenting of ductus arteriosus, including moderately tortuous ducts, is a safe palliation for patients withductal-dependent pulmonary circulation. Incomplete stenting of the duct invariably results in ductal stenosis andcompromised pulmonary flow.

Key Words. Ductal-Dependent Pulmonary Circulation; Cardiac Catheterization; Stent Dilatation

Introduction

Conventional management of neonates withductal-dependent pulmonary flow entails

maintaining ductal patency using prostaglandinE1 infusion followed by surgical palliation withBlalock-Taussig shunt (B-T shunt). Present mor-tality of B-T shunt is reported to be as high as10%.1–3 In addition, complications associated withB-T shunt are not uncommon, some of which mayadversely affect future surgical interventions.4–6

Although initial results of stent dilation of ductusarteriosus were discouraging,7,8 recently, it is

suggested to be a safe and effective alternate toB-T shunt in these patients.9,10 Use of rigid stain-less steel stents, stiff wires, and long sheaths verylikely contributed to the disappointing initialresults of this palliation.9 Development of flexiblecoronary stents11 and better understanding of theprocedure, both with respect to patient selectionand technical aspects, convinced us to reexaminethe role of arterial duct stenting in this patientpopulation. This report summarizes our experi-ence with this procedure since July 2003 until thewriting of this report.

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© 2008 Copyright the AuthorsJournal Compilation © 2008 Wiley Periodicals, Inc. Congenit Heart Dis. 2008;3:241–249

Methods and Procedures

Patient PopulationAll patients with ductal-dependent pulmonary cir-culation who were sent to the cardiac catheteriza-tion laboratory for ductal stenting from July 2003to November 2006 constitute the study population.

All eligible patients underwent at least a diag-nostic catheterization and none were excludedbased on echocardiographic evaluation alone.

Exclusion CriteriaPatients with chromosomal disorders associatedwith severe mental retardation, trisomy 18 or 13,weighing <1500 g, untreated sepsis, severe birthasphyxia with poor neurological outcome as perevaluation by pediatric neurologist, those withpulmonary artery branches stenosis and verytortuous patent ductus arteriosus (PDA) withmultiple turns as judged by echocardiogram orangiogram were not considered eligible for theprocedure.

ProcedureAll procedures were performed under deep seda-tion using intravenous fentanyl and midazolam.Venous access was obtained using a 5Fr sheath inthe femoral vein, and a 4Fr sheath was placedin femoral artery. Aortogram was performed instraight antero-posterior and lateral projection.Additional aortograms were performed in theright anterior oblique and/or left axial obliqueprojection to clarify the morphology of the ductusarteriosus. The PDA was anatomically classified asconical straight, vertical straight, mildly tortuous(one bend), and moderately tortuous (two bends)(Figures 1 and 2).

The diameter and length of the ductus weremeasured as shown in Figure 3. In the case ofmoderately tortuous PDA, a hand injection usingan end-hole catheter advanced over a 0.014-inchwire positioned in the pulmonary artery across theductus arteriosus was found to be very helpful inidentifying overall anatomy of PDA and its inser-tion into the pulmonary artery. To our advantage,PDA is significantly straightened by the wire,allowing correct measurement of ductus arteriosuslength and correct positioning and deployment ofthe stent. Therefore, the length of the stent to beused was selected based on this angiogram ratherthan the aortogram. The ductus was then accessedusing the same end-hole catheter over a 0.014-inchguidewire that was positioned across the duct intothe pulmonary artery. Different types of catheterswere used in different cases, but a cut 4Fr pigtailwas felt to be the best catheter for negotiating thePDA. Prostaglandin E1 infusion was discontinuedimmediately after the wire was in place across theductus in the pulmonary artery, and a coronarystent was then advanced over the same 0.014-inchwire and deployed in the PDA. In all cases, pre-mounted coronary stents with good scaffoldingproperties were used (Table 1). No long sheath orguiding catheter was used to advance and positionthe stent. Stent measuring either the same or 0.5–1 mm larger than the diameter of the duct and longenough to cover the ductus arteriosus was selectedunless the appropriate size was not available; inwhich case, two stents were used to attain therequired length. In our initial protocol, a secondstent was deployed in case more than 1 mm of theductus at the pulmonary end or more than 2 mm atthe aortic end extended beyond the stent as seen inrepeat aortogram. This was later modified to cover

Figure 1. Shows comma-shaped ductus arteriosus with one bend (arrow) before (left and middle panels) and after stenting(right panel). B-T shunt, Blalock-Taussig shunt.

Arif et al.242

Congenit Heart Dis. 2008;3:241–249

the entire length of the ductus without leaving anysegment of the duct uncovered. Like any vascularstenting, extreme care was exercised to ensureappropriate positioning of the stent. In our experi-ence, a stent protruding 1 mm in the pulmonaryartery or aorta prevents PDA constriction andensures reliable pulmonary flow and was of noclinical significance both with regard to aorticblood flow and subsequent surgical repair.

Cefazolin 50 mg/kg was given intravenouslyprophylactically to all patients immediately after

stent deployment and continued for 24 hours at8-hourly intervals at a dose of 25 mg/kg/dose.Intravenous heparin was maintained in all patientsfor 24–48 hours to keep partial thromboplastintime between 60 and 80 seconds. All patients alsoreceived aspirin 5 mg/kg/day and nine patientsadditionally received dipyridamole 5 mg/kg/day,divided every 12 hours, and these were continueduntil undergoing second-stage palliation or com-plete repair.

Results

DemographicsTwenty-one patients were brought to the cardiaccatheterization laboratory for possible stentimplantation. Five patients did not qualify for theprocedure because of complex tortuousity of theductus arteriosus (two patients) or branch pulmo-nary artery stenosis (three patients). Sixteen (76%)patients qualified to undergo the procedure. Themean age of the patients at the time of ductal stentimplantation was 24 � 17.5 days (median 18.5days, range = 2–62 days), nine were male (56%).

Figure 2. Shows moderately tortuous ductus arteriosus (PDA) with three bends (arrows) before (left and middle panels) andafter stenting (right panel). Note that the stent has completely straightened the PDA.

1

2

Figure 3. Showing a mildly curved patent ductus arterio-sus. In order to select the accurate length of the stent,number 1 and number 2 are measured and added together.In order to choose the accurate diameter of the stent, thenarrowest diameter of the duct is measured, and this diam-eter or +1 mm is chosen as the diameter of the stent to beimplanted.

Table 1. Types of Stents Used

Trade Name Manufacturers n %

1. Driver Medtronic Inc., Minneapolis, Minnesota 6 302. S7 5 253. BE 3 154. Plamaz

GenesisCordis Corp., Johnson & Johnson, Miami,

Florida1 5

5. Costar Biotronic, Conor Medsystems, Menlo Park,California

1 5

6. Vision Guidant Corp., Santaclara, California 2 107. Express Boston Scientific Corp., Natick, MA 2 10


Patent Ductus Arteriosus Stenting in Ductal Dependent Pulmonary Circulation 243

The mean body weight was 2.9 � 0.35 kg(median = 3 kg, range = 2.2–3.4 kg) (Table 2).

Associated Congenital Heart DiseasesDetailed cardiac diagnoses of the whole group aresummarized in Table 2. Thirteen patients had pul-monary atresia (intact ventricular septum = 8, ven-tricular septal defect = 1, tetralogy of Fallot = 2,atrioventricular septal defect = 2). Three patientshad critical pulmonary stenosis. Eleven patients(68.7%) had univentricular physiology; theremaining were considered suitable for biventricu-lar or 11/2 ventricle repair.

Morphology of PDA and Results of CatheterizationThe morphology of the ductus in 16 patients whounderwent stenting was mildly tortuous (onebend) in four, moderately tortuous (two bends) infour, conical in four, and vertical in four. Themean diameter of the ductus arteriosus was3.9 � 0.5 mm (range = 3–4.5 mm). The meandiameter and length of the stent implanted were3.9 � 0.72 mm (range = 2.7–6 mm, median = 4)and 15.4 � 3.16 mm (range = 9–20 mm, median =16), respectively. During primary procedure,single stent was implanted in 12 patients and twostents were implanted in two. Mean fluoroscopy

and procedure times were 22.16 � 12.5 minutes(range = 10.9–54 minutes) and 107.9 � 34.5minutes (range = 54–175 minutes). Mean volumeof intravenous contrast received was 28 � 6.6 mL(9.6 mL/kg) (Table 3). The ductus arteriosus wasnot completely covered with stent in five patientsat the time of primary procedure; all during theinitial part of our experience. Two patients withpulmonary atresia underwent stiff wire perforationand balloon pulmonary valvuloplasty as primaryprocedure, followed by stent dilation of the duct30 days and 10 days later because of inability towean off prostaglandin E1. The stent migrated tothe right pulmonary artery in two cases due to thefact that the stent was used 1 mm smaller than thediameter of the ductus arteriosus. In one case,the PDA diameter was underestimated, and in theother, appropriate size was not available. Thesepatients underwent placement of B-T shunt alongwith removal of stents. Successful ductal stentingwas accomplished without catheterization-relatedmorbidity in 14/16 patients (Figure 4A, B).

No additional procedure was performed intwo patients with critical pulmonary stenosis.Femoral arterial pulse was palpable followingductal stenting in all patients. This may bebecause, as per our protocol, heparin infusion

Table 2. Demographics and Clinical Profiles of Patients

Diagnosis Age (days) Weight (kg) Sex

1 PA, IVS 2 3 Female2 TA, PA, IVS Small RV 19 2.4 Male3 EBSTEIN ANOMALY, PA, IVS 18 2.7 Female4 PA, IVS Hypoplastic RV 10 2.5 Male5 TA, PA, IVS 6 2.8 Female6 PA, IVS PDA 5 3 Male7 PA, IVS, Sever TR 13 3 Female8 PA, IVS HRV 9 3.1 Male9 DEXTROCARDIA, PA AVSD. 6 3 Female

10 PA, VSD, Hypoplastic RV 42 3.1 Female11 TOF, PA 17 3.3 Male12 TOF, PA, 8 3 Male13 PA, AVSD 63 3.2 Male14 Critical PS, PDA 19 2.7 Male15 Critical PS, PDA 3 2 Female16 d-TGA, PS, VSD 30 2.2 Male

AVSD, atrioventricular septal defect; IVS, intact ventricular septum; PA, pulmonary atresia; PDA, patent ductus arteriosus; PS: pulmonary stenosis; RV, rightventricle; TA, tricuspid atresia; TGA, transposition of great arteries; TOF, tetrology of Fallot; TR, tricuspid regurge; VSD, ventricular septal defect.

Table 3. Angiographic Data of Patients

PDADiameter (mm)

StentDiameter (mm)

StentLength (mm)

FluoroscopyTime (minute)

ProcedureTime (minute)

Contrast(mL)

Mean 3.9 3.9 15.4 22.16 107.9 28Range 3–4.5 2.7–6 9–20 10.9–54 54–175 20–46Mode 4.5 3.5 18 19.3 103 30

PDA, patent ductus arteriosus.

Arif et al.244


was initiated immediately after the procedure tomaintain stent patency and continued for 48hours in all cases. Also, aspirin in all and dipy-ridamole in nine cases was also started immedi-ately after the procedure.

Short-term Follow-upOf the nine patients in whom the ductus arteriosuswas covered completely, only one patient requiredredilation of the stent for reduced oxygen satura-tion, presumably due to intimal proliferation 3months after the initial procedure. In threepatients, 2 mm of the duct remained uncovered bythe stent at the aortic side and in two patients only1 mm of the duct was not covered at the pulmo-nary side (Figure 5). Four of them developedductal stenosis and significant oxygen desatura-tion. They presented at a mean of 53 � 36 days(range 7 days–10 weeks) after the procedure.

Three of them responded well to the placement ofthe second stent to cover the unstented segmentof the duct, but one expired. He had unbalancedcomplete atrioventricular canal defect and pulmo-nary atresia and presented with severe oxygendesaturation and subtotal occlusion of the stent7 weeks after the initial procedure. Oxygen satu-ration improved to 75% after placement ofsecond stent, but he died of multi-organ failureas he had a suffered prolonged period of severehypotension and hypoxemia. Another patient diedpost-stenting; he had tetralogy of Fallot with pul-monary atresia and was doing well post-stentingbut died 3 days later of aspiration pneumonia.

Midterm Follow-upOf the remaining 12 patients, seven had univen-tricular physiology. One was lost to follow-up, fiveunderwent and one is waiting to undergo Glenn

A

Total number of patients with Ductal Dependent Pulmonary circulation

21

Stent not done

5Stent attempted

16

Complex Tortous duct

2

Pulmonary branch

stenosis 3 Stent migration

2Successful

stenting 14

BT Shunt

B

Successful stent 14

Biventricular physiology 5 Univentricular physiology 9

Biventricular

repair 2Waiting for

Biventricular orone and half

ventricular repair

3

Glenn

shunt 5

Died

2Survive

3

Died

2Waiting

for Glenn 1Lost follow

up 1

Figure 4. (A) Outcome of all the study patients considered suitable for possible stent dilation of patent ductus arteriosus. (B)Outcome of patients who underwent successful primary stent dilation of patent ductus arteriosus.



procedure. Of the five patients who underwentGlenn procedure, two expired but the remainingthree are doing very well, and their mean oxygensaturation is 85% (range = 80%–90%) at a meanfollow-up of 8 months. The two patients whoexpired had pulmonary atresia with intact ventricu-lar septum and hypoplastic right ventricle. Glennshunt appeared to have failed because of pulmonaryhypertension. The first one had conical PDA,ductal stenting was performed at 2 days of age, and3 months later underwent stent dilation for partialocclusion of the stent possibly due to intimal pro-liferation. Glenn shunt was performed at 4 monthsof age. Cardiac catheterization prior to Glennshowed systemic oxygen saturation of 63%, meanpulmonary artery pressure (PAP) was 16 mm Hg,left ventricular end-diastolic pressure was8 mm Hg, pulmonary vascular resistance index was3.4 wu/m2, and normal pulmonary arteries. Thepatient developed severe upper body edema andoxygen desaturation despite maximum pulmonaryvasodilator therapy including nitric oxide inhala-tion. Repeat catheterization showed a mean PAP of20 mm Hg on 100% oxygen and NO inhalation at40 ppm. He developed severe upper body edema,severe hypoxemia, metabolic acidosis, and multi-organ dysfunction and expired. In the second case,ductal stenting was uneventful and requiredno additional intervention. Glenn shunt was per-formed 3 months later at an age of 41/2 months.Cardiac catheterization showed systemic satura-tion of 77%; mean PAP was 25, pulmonary vascularresistance index was 4 wu/m2, left ventricular end-diastolic pressure was 7 mm Hg. Postoperativecourse was very similar to the first patient.

All the five patients deemed suitable for biven-tricular or 11/2 ventricular repair are doing very

well. Two have undergone successful biventricularrepair and right ventricular over hall 18 months and22 months after ductal stenting. Two of them havesuccessfully undergone bi-ventricular repair. Theremaining three patients are doing well and theirmean oxygen saturation is 82.3% � 6.4% on roomair at a follow-up of 12.75 � 6.1 months. Two ofthem have required no further intervention andone underwent redilation of the stent and the otherunderwent implantation of the second stent torelieve oxygen desaturation. Follow-up of all the 14patients is summarized in Figures 4A and B.

Need for Second StentA total of six patients required second stent as thefirst stent failed to cover the PDA completely. Intwo patients, the second stent was implanted at thetime of primary procedure to ensure completestenting of PDA. The remaining four had under-gone stenting during the initial part of our expe-rience; part of their PDA was not covered withstent during the initial procedure, and they pre-sented with significant oxygen desaturation atfollow-up. Morphology of the PDA was tortuousin three, conical in two, and vertical in one. Noneof our last six patients required any reinterven-tion over a mean follow-up of 12.2 months(range = 4–29 months).

MortalityThere was no catheterization-related mortality.Two patients (14.3%) died during short-termfollow-up and two more patients died after under-going Glenn procedure. Thus, the cumulativemortality was 4/14 (28.5%).

Figure 5. Shows the segment of the duct (black interrupted arrow) not covered by the stent (A), which was covered byimplanting the second stent (black arrow—B).

Arif et al.246


Discussion

Stent dilation of ductus arteriosus has been pro-posed as an alternate to B-T shunt for newbornswith ductal-dependent pulmonary. Initial disap-pointing clinical experience led to recommen-dations against routine stenting of the ductus arte-riosus.7,8 However, better results have beenrecently reported in ductal-dependent pulmonarycirculation9,10 with the use of soft wires and stentsused for coronary artery stenting and by makingsure to completely stent the ductus in its entirelength.

Our ExperienceIn this series, we were able to stent ductus arterio-sus in 14 of the 16 patients who met the selectioncriteria. Seven of these patients had mild to mod-erately tortuous ductus with one or two bends,respectively. Thus, our experience further sup-ports that ductal stenting in ductal-dependent pul-monary circulation is technically feasible and safein a selected population, and it further shows thatductal stenting can be performed not only instraight conical but also in ductus arteriosus withone or two bends.

Exact measurement of the length of a tortuousduct is difficult to ascertain, especially using theimages obtained at initial aortogram only. Asmentioned in the methods section, a hand injec-tion after positioning the 0.014-inch wire consid-erably straightens the PDA and allows betterdefinition of its anatomy and selection of appro-priate size stent to cover the entire length ofPDA. In our experience, this technique is quitehelpful to achieve successful stenting of theentire length of moderately tortuous PDA.Despite these measures, exact measurement ofthe length of a tortuous PDA still remains a chal-lenge and a small segment of the ductus may beleft uncovered in some cases, necessitating use ofsecond stent. In this series, two stents were usedin six of seven patients with tortuous PDA.Application of the software used to measurelength for coronary artery stenting might be auseful tool to overcome this limitation of theprocedure but has not been utilized by any of thegroup to our knowledge.

Patients with no other source of pulmonaryflow such as those with pulmonary atresia deserveadditional comments. Manipulation of wires andcatheters in the ductus arteriosus occasionallyinduces ductal spasm. Therefore, patients with noadditional source of pulmonary blood flow are at

risk of developing oxygen desaturation. However,severe oxygen desaturation occurs rarely and werecommend rapid deployment of stent if oxygendesaturation is not associated with bradycardia;otherwise, removal of wires and catheters invari-ably results in improvement of oxygen desatura-tion and stable hemodynamics. In one case,prostaglandin E1 infusion was reinitiated tempo-rarily after such an event, and ductal stenting wassuccessfully performed. In the current series,no procedure was abandoned because of thiscomplication.

Our experience also supports the findings ofother investigators9,10 that leaving any segmentof the duct left uncovered with stent invariablyresults in ductal stenosis and a need forre-stenting, and that using a stent 1–2 mm longerthan the ductus itself protects against ductal steno-sis. This approach has worked well and in the lastsix patients in this series in whom the ductus arte-riosus was completely covered by stent; reliablepulmonary flow is maintained in five patients overa mean period of about 9 months without anyfurther intervention. One patient with a conicalduct that was stented completely developed partialocclusion of the stent over a long segment dueto intimal proliferation requiring re-stenting.Thus, intimal proliferation can result in occlusionof the stent and, therefore, a strict follow-up ismandatory to achieve a successful outcome,although sudden occlusion of the stent appears tobe rare.

Pulmonary Vasculature and PDA StentingFour out of five patients subjected to Glenn pro-cedure developed elevated mean PAP and pulmo-nary vascular resistance even as early as 3 monthsafter stenting (Table 4). This is in contrast topatients who undergo palliation with B-T shunt,who rarely develop pulmonary hypertension andelevated pulmonary vascular resistance even after6–8 months or longer. This is an important and

Table 4. Pre-Glenn Hemodynamic Data

Arterial Oxygen Saturation % 67 63 77 87 64

Qp : Qs 0.7 0.9 1.5 7 2Mean PAP (mm Hg) 17 16 25 23 13–14PVR (Wood Unit/m2) 4.3 3.4 4 3 ?LVEDP (mm Hg) 13 8 7 4 12Age at Cath (months) 11 4 4.5 6 5Follow up after stenting (months) 11 4 3 6 5

Qp, pulmonary cardiac index; Qs, systemic cardiac index; PAP, pulmonaryartery pressure, LVEDP, left ventricular end-diastolic pressure; Cath, cardiaccatheterization; PVR, pulmonary vascular resistance.



worrisome observation that has not been reportedin previous reports. We lack a definite explanationfor development of pulmonary hypertension at anaccelerated rate at this point. However, while theB-T shunt and stented ductus are physiologicallysimilar in some respect as a source for pulmonaryflow, the two might be different in other aspects.The Goretex tube used for B-T shunt is about3–3.5 cm long in contrast to the stented ductusarteriosus that is only 1.5–2 cm long. In addition,the B-T shunt is anastomosed to distal innominateartery, which also has a much smaller diameterthan the ductal ampulla in general and, therefore,further contributes to the length of a narrow tubewith small diameter between aorta and the pulmo-nary artery (Figure 6). Based on Poiseuille’s law,12

longer length of the B-T shunt should offer higherresistance and may restrict transmission of aorticpressure to the pulmonary artery compared toshorter ductus arteriosus. This could be theoreti-cally a plausible explanation for the disparity in therate at which elevated PAP develops in those pal-liated with ductus arteriosus stenting and B-Tshunt, but remains to be proven.

Both patients who died after undergoing Glennshunt manifested clear sign and symptoms of ahypertensive poorly functioning Glenn shunt andcontributed to overall high mortality in this series.Therefore, it might be prudent in the meantime tooffer second-stage palliation 2–3 months afterductal stenting rather than later as this approachmay help in reducing overall mortality to accept-able level.

Ductal MorphologyIn our experience, very tortuous ducts with mul-tiple bends and curves are not suitable for stentingat present for two reasons. First, these ducts aretechnically much more challenging because ofgreat difficulty in clearly defining the anatomy ofthe duct with the current technology. This in turnmakes the selection of appropriate size stent verydifficult for the operator, which has a great impacton the outcome of the procedure. Second, often itis not possible to maintain the wire in a positionstable enough to advance the stent into the ductusarteriosus. For these reasons, such cases wereexcluded in this study.

However, stenting can be successfully per-formed even in large PDA as an area of stenosis/narrowing is invariably present at the site of ductalinsertion into the pulmonary artery despite re-ceiving intravenous prostaglandin infusion. Thisallows a 3.5–4-mm diameter stent to hold verywell even if the rest of the PDA is larger in diam-eter as it constricts on the stent and further stabi-lizes it. During our initial experience, we ended upusing a 6-mm diameter stent for a large PDA.Later, we modified our approach because ofpotential concerns of pulmonary over circulation,congestive heart failure, and development of pul-monary hypertension with the use of such a largestent. The 3.5–4 mm stent, just like a standardB-T shunt, allows adequate pulmonary flow.Hypothetically, in case of a large tubular PDA,B-T shunt should be preferred over PDA stenting,especially in patients with univentricular

B–T SHUNTSTENT IN PDA

Figure 6. Shows the comparative lengths of a Blalock-Taussig (B-T) shunt (left panel) and a stented patent ductusarteriosus (PDA; right panel). The stented PDA is much shorter in length than the combined length of the innominate arteryand the B-T shunt. According to the Poiseuille’s law, shorter length of the stented PDA could contribute to the relatively earlydevelopment of pulmonary hypertension compared to the B-T shunt.

Arif et al.248


physiology because of concerns of congestive heartfailure and pulmonary hypertension.

Conclusion

Ductal stenting appears to be a suitable alternateto placement of B-T shunt in patients with ductal-dependent pulmonary flow. It is technically fea-sible even in patients with mild to moderatelytortuous ductus arteriosus having one or twobends. Full-length stenting of the duct withoutleaving any ductal tissue extending beyond thestent is mandatory for satisfactory outcome. Twostents are often needed in case of tortuous PDA, asexact estimation of the length is difficult in thesecases. Elevated PAP and pulmonary vascular resis-tance may develop at an accelerated rate in somecases after ductal stenting, which has importantimplication as to the timing of offering second-stage surgical repair especially for those withuniventricular physiology and over all outcome ofPDA stenting.

Corresponding Author: Arif Hussain, MD, Section ofPediatric Cardiology, King Faisal Specialist Hospitaland Research Center, MBC J-16, PO Box 40047,Jeddah, Saudi Arabia. Tel: (+966) 0-5033-69806;Fax: (+966) 0-2-663-7581; E-mail: [email protected]

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