Transcatheter Closure of Left Pulmonary Artery to Left Atrium Fistula in a Neonate Using Amplatzer Duct Occluder I

ABSTRACT: A direct-fistula type communication between branch pulmonary artery (PA) to left atrium (LA), particularly left PA to LA, is a very rare congenital cardiopulmonary disorder. Although surgical repair is the conventional treatment, transcatheter device or coil closure is feasible in selected cases of a relatively frequent variant — right PA to LA fistula. Ours is the first case of successful transcatheter closure of a large left PA to LA fistula with Amplatzer duct occluder in a cyanotic neonate by transseptal approach.

J INVASIVE CARDIOL 2014;26(7):E91-E94

Key words: ADO, fistula

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The pulmonary artery (PA) to left atrium (LA) fistula is a rare variant of pulmonary arteriovenous fistula (PAVF). Most cases are congenital, with a few post traumatic in origin.^1-3 Right PA to LA fistula is the most common subtype and accounts for more than 95% of PA to LA fistula cases.⁴ Only 3 cases of left PA to LA fistula have been reported in the literature.^3,5,6 PA to LA fistula is an uncommon variant of PAVF, but shares the same clinical triad of central cyanosis, normal cardiovascular examination, and a shadow parallel to the left heart border on chest x-ray. Doppler echocardiography and angiographic delineation of the anatomy are essential to define the most suitable mode of intervention. To eliminate the persistent right to left shunt with consequent deleterious complications, either surgical correction or transcatheter closure should be individualized and performed as early as possible.^7,8

Case Report. A full-term neonate weighing 3200 g was born via cesarian section to 29 years old primigravida. A fetal echocardiogram performed at the fifth month of gestation was normal. The neonate had mild central cyanosis and transcutaneous oxygen saturation was 85% on the first day of life. The screening two-dimensional echocardiography and color Doppler study within the first few hours of life showed small restrictive closing ductus; the remaining findings were normal. Persistent central cyanosis with frequent episodes of low oxygen saturation on high-flow oxygen and normal precordial examination prompted cardiac reevaluation. Follow-up echocardiography study revealed mild enlargement of LA and left ventricle (LV), disproportionate dilatation of left PA, small right PA, and no discernible ductal flow. There was unusual dilatation of the left atrial appendage (LAA) (Figure 1A). Color Doppler showed mosaic turbulent flow pattern at the LAA along with continuous venous signal on the pulse-wave Doppler analysis, which raised the possibility of an abnormal vascular communication to the LA. Except for mild pulmonary hypertension, the remaining echocardiography findings were normal. Cardiac multislice computed tomography (MSCT) scan was performed to further delineate the branch pulmonary arteries, pulmonary venous drainage, and anomalous vascular communication at the LAA. The MSCT findings confirmed a direct tubular tortuous communication with midway narrowing between the dilated left PA and LAA (Figures 1A, 2A, 2B). The main pulmonary artery segment was normal, while the right PA was hypoplastic. Written and informed consent was obtained from the parents and cardiac catheterization was planned with the intention to perform a therapeutic intervention. Under monitored anesthesia using a ketamine and midazolam combination, right femoral vascular accesses were obtained. Hemodynamic data showed systemic arterial pressure of 95/47/59 mm Hg and PA pressure of 25/10/16 mm Hg. Selective left PA angiography in left anterior oblique and lateral views with 4 Fr Judkin’s right (JR) catheter defined the large fistula between left PA and LA with mild narrowing before insertion into the appendage (Figure 3A). The conical shape of the narrow restrictive mid-distal segment of the fistula appeared suitable for the device closure. An additional left femoral venous access was obtained and a 4 Fr multipurpose catheter was placed into the LA through the small atrial septal defect. A 0.14˝ Cougar XT PTCA guidewire (Medtronic) was passed through the tubular fistulous connection into the main PA, and then exchanged with an Amplatzer stiff guidewire to advance the delivery system over it. A 6 Fr Mullins sheath (Cook Medical, Inc) was advanced over the superstiff guidewire across the fistula into the main PA. Under guidance of selective left PA angiography with 4 Fr JR, an 8/6 mm Amplatzer duct occluder (St Jude Medical, Inc) was deployed across the narrow segment by technique similar to patent ductus arteriosus device closure. Postprocedure transcutaneous oxygen saturation increased to 96%. Left PA angiography showed complete closure of fistula without any residual flow or distortion of the left PA (Figure 3B). The procedure was accomplished with 16 minutes of fluoroscopy time. The baby was shifted to the neonatal Intensive Care Unit in stable hemodynamic condition without any procedural complications. Echocardiography documented stable device in situ without any residual flow (Figure 4A). The patient was discharged on the fifth postprocedural day with normal oxygen saturation in room air. Clinical follow-up at 3 months revealed normal oxygen saturation and device in situ on echocardiography. However, proximal right PA narrowing was more obvious with mild flow acceleration. Computed tomography angiography at 3 months showed complete obliteration of the left PA to LA fistula, dilated left PA and a small left upper pulmonary vein joining the distal-most segment of the communication near the LAA (Figure 4B).

Discussion. The PA to LA fistula, a clinical and embryologic variant of PAVF, is an uncommon congenital or acquired cardiopulmonary vascular anomaly.^1,2 Since the first surgical repair by Blalock, nearly 70 cases of right PA to LA fistula have been described, while left PA to LA fistula is a much less common variant.^4-6,8,9 The clinical presentation of fistula is primarily dependent on the magnitude of the right to left shunt. Newborns with large fistulas often present with central cyanosis, low oxygen saturation, and respiratory distress, which necessitates urgent intervention. Although the tubular opacity on routine chest x-ray in a patient with central cyanosis and normal precordial examination raises the possibility of a fistula, documentation of a pouch-like aneurysmal sac posterior to the LA with communication to the LA on echocardiography is diagnostic. The provisional echocardiographic diagnosis of left PA to LA fistula in our case was primarily based on disproportionately large left PA and mosaic turbulent flow in aneurysmal LAA. In our patient, MSCT angiographic volume-rendered three-dimensional images provided an excellent overview of the entire course of the fistula that had guided us to plan transcatheter closure. Surgical closure of fistulas in neonates was disappointing in the initial era, but recent reports have shown encouraging results with surgical treatment and in selected cases with transcatheter intervention as well.^3,10,11 The conventional technique of transcatheter closure of PAVF or variants conceptualizes the antegrade delivery of coil or device at the narrow segment of the fistula. The fistula closure in our case was accomplished by transatrial septal approach and an Amplatzer ductal occluder (ADO) was deployed to achieve complete closure. Other embolization materials used for similar purpose are coils, septal occluders, and vascular plugs.^7,10-12 The inherent risk of distal embolization of coils into the systemic circulation and higher rate of recanalization are the major limitations and precluded the use of coils into PA to LA fistula. The Amplatzer vascular plug appears the most suitable alternative to ADO, as this can be delivered to the desired site by using a small-caliber guiding catheter.¹² In our patient, the targeted mid-distal segment of the tortuous tunnel-like fistula had abrupt narrowing after the dilated sac at the distal end of the left PA. To minimize the potential risk of distal migration or embolization of the ADO device into the LA, we planned to deploy the distal skirt first into the sac, so the waist of the ADO can fit into the narrow restricted angulated part of the fistula. A small patent foramen ovale-like ostium secundum atrial septal defect in our patient facilitated the retrograde approach. In fact, the technique of transseptal retrograde approach to close the right PA to LA fistula using duct occluder has already been reported.¹¹ The persistent improvement in clinical status corroborating with complete closure of the shunt on MSCT evaluation at 3 months further establishes the safety and efficacy of innovative transcatheter approach in neonates with a rare congenital disorder. To our knowledge, ours is the first case report of transcatheter device closure of large left PA to LA fistula using ADO in a neonate presented with severe cyanosis.

Conclusion. Transcatheter closure of left PA to LA fistula in a neonate by transseptal approach using an ADO is a safe and feasible option in the short term. In addition to diagnostic and therapeutic evaluations, MSCT pulmonary angiography plays a crucial role in deciding the intervention strategy to close the pulmonary fistula in neonates.

References

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From the UNM Institute of Cardiology and Research Centre, Ahmedabad, Gujarat, India.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted July 1, 2013, provisional acceptance given August 19, 2013, final version accepted February 27, 2014.

Address for correspondence: Bhavesh M. Thakkar, MD, DM, Associate Professor, UNM Institute of Cardiology and Research Centre, 09, Shreedher Tenament, Bapunagar, Ahmedabad, Gujarat 380024, India. Email: bthakkarin@yahoo.co.in