Transcatheter closure of large right pulmonary artery-to-left atrial fistula.

We report the successful transcatheter closure of right pulmonary artery fistula to left atrium in a six-year-old boy, who had presented with cyanosis and shortness of breath. The two-dimensional echocardiogram with bubble contrast study demonstrated the communication between right pulmonary artery and left atrium. Computerized tomography confirmed the diagnosis and delineated the anatomy. The fistula was closed successfully by a transcatheter trans-septal approach using an 18/20 duct occluder.

INTRODUCTION

Right pulmonary artery (RPA)-to-left atrial (LA) fistula is one of the rare causes of central cyanosis.[1] Untreated cases may suffer from hyperviscosity syndrome due to chronic hypoxemia, brain abscess, systemic thromboembolism, or cerebrovascular accident.[12] There are nearly 60 cases of RPA-to-LA communication reported in the literature.[3] Management of these cases comprises surgical ligation of the fistulous tract or transcatheter closure by using a device or coils.[14] We report the successful closure of an RPA-to-LA fistula by a transcatheter trans-septal approach using a duct occluder in a child with severe cyanosis.

CASE REPORT

A six-year-old child was referred for the evaluation of cyanosis and dyspnea. On examination, there was severe cyanosis (SpO2: 68%) with grade III clubbing. Examination of the cardiovascular system revealed normal heart sounds and no murmurs. Chest roentgenogram showed homogenous opacity noted in the right hilar region. Electrocardiogram showed no abnormality. Transthoracic echocardiogram (TTE) showed communication between RPA and LA [Figure 1a] in high-parasternal short-axis view. Bubble contrast study confirmed the shunt between RPA and LA [Figure 1b]. A computerized tomography confirmed the large tortuous communication between RPA and LA [Figure 2].

Figure 1

(a) TTE showing fistulous communication between right pulmonary artery and left atrium in high parasternal short-axis view; (b) bubble contrast echocardiogram demonstrating filling of left atrium from the pulmonary vein (thick arrow); (c) well-positioned duct occluder device within the fistulous tract

Figure 2

Computerized tomogram angiography in axial (a) and sagittal (b) planes showing a large right pulmonary artery-to-left atrial fistula (arrow)

The child was planned for transcatheter closure of the RPA-to-LA fistula after informed consent, under intravenous general anesthesia. Access from both the femoral veins and right femoral artery were obtained. An angiogram was performed to profile the RPA-to-LA communication [Figure 3a]. A 5F multipurpose catheter (Cook Inc, Bloomington, IN) could be easily negotiated from the RPA to LA through the fistulous communication. Balloon sizing was done using an 18 × 40 mm Atlas balloon (C. R. Bard. Inc, USA) due to nonavailability of low-profile compliant balloons [Figure 3b] and the narrowest diameter measured was 18 mm. The widest diameter was at the RPA and appeared suitable for transcatheter closure; hence, it was decided to close the fistula from the LA side. Trans-septal puncture was performed using a pediatric Brockenbrough needle and Mullins sheath. A 0.032” angulated glide wire (Terumo Medical corp., Somerset, NJ) was advanced into the LA and snared using a gooseneck snare (ev3 Endovascular Inc., Plymouth, Minnesota, USA) leading to the formation of venovenous loop from the left femoral vein - RPA - LA - RA to the right femoral vein [Figure 3c]. A 9F delivery sheath was advanced over the glide wire from the right femoral vein across the interatrial septum and then through the fistulous tract from LA to RPA. An 18/20 mm duct occluder (Heart R, Lifetech Scientific, Shenzhen) was selected to close the RPA-to-LA fistula. The retention disc of the device was positioned on the floor of the RPA and the remaining disc released in the fistulous tract. A selective RPA angiogram showed a well-positioned device and no residual leak [Figure 3d]. The systemic saturation improved from 68 to 96% immediately after closure of the fistula. There were no procedure-related complications. The child was observed for 48 hours prior to discharge, and was asymptomatic at a follow-up after six months.

Figure 3

(a) Cine angiogram demonstrating right pulmonary artery-to-left atrial (RPA-to-LA) fistula in right anterior oblique view; (b) fluoroscopy showing balloon sizing of the narrowest diameter of the communication; (c) cine fluoroscopy in anterioposterior projection showing formation of venovenous loop; (d) angiogram after deployment of the device (white arrow) showing complete abolition of shunt from RPA to LA

DISCUSSION

Presentation of direct RPA-to-LA fistula ranges from mild to severe central cyanosis, exertional dyspnea, or rarely a complication of right-to-left shunt when presented later in life. De Souza e Silva et al. described three types of RPA-to-LA fistula based on its opening site.[5] In type I, RPA branches and pulmonary veins are normal but a fistulous channel connects the RPA to LA. In type II, the right lower pulmonary vein is absent and the lower lobe RPA branch drains directly into the LA, as an aneurysmal sac at the insertion site of the right lower pulmonary vein. In type III, pulmonary veins drain into the abnormal channel that connects the RPA and LA as a fistula. Subsequently, the fourth type was added by Ohara et al., which is similar to type II where the pulmonary veins enter into the aneurysmal sac.[6] Our case is a classic example of type II where the RPA opens into a chamber proximal to the LA.

No definite embryological explanation has been described for the RPA-to-LA communication. Some hypothesized that this anomaly may result from a communication between the RPA and a primitive pulmonary vein and later the pulmonary vein would become incorporated into the wall of the LA, resulting in a fistulous connection between the RPA and LA.[78] An atrial septal defect is the most commonly associated intracardiac anomaly; however, pulmonary abnormalities include absence of the lower or middle lobe, right lung sequestration, and diverticulum of the right main bronchus, as have been reported in the literature.[910] We did not notice any such abnormality in our patient.

In our case, the RPA-to-LA fistula is large and type II. The aneurysmal sac is directly communicating with the superior aspect of LA. We thought that forming a venovenous loop after the trans-septal puncture maybe ideal to position the sheath in the proximal RPA.[1112] The duct occluder can be positioned easily on the floor of the fistula if we place the delivery sheath. The antegrade deployment from the right ventricle to the main pulmonary artery maybe an alternative method; however, only double-disc devices should be used. It maybe difficult to position the double-disc device and may compromise the distal RPA flow if the device is not deployed properly. The major advantage of the venovenous route is (i) to deploy the duct occluder and (ii) that it can be pulled as distally as possible to prevent distal RPA obstruction.

We conclude that systematic evaluation and assessment can accurately diagnose an RPA-to-LA fistula. Choice of the procedure is usually determined by the anatomy and type of the fistula. Transcatheter closure using a duct occluder appears to be a good alternative.