Percutaneous Occlusion of Patent Ductus Arteriosus with the
Nit-Occlud® Device in an Adult Patient

Percutaneous occlusion of a patent ductus arteriosus (PDA) is actually a standard procedure for the treatment of this congenital heart defect. Different devices have been used for the last 20 years with high rates of success.^{1,2,4,8,11,13,14} A few exceptions include low-weight premature newborns and ductus endarteritis. Anatomic features of the ductus, the presence of an aortic ampulla and its minimal diameter are to be considered when the closing device is selected.⁶ We report the case of an adult patient with a PDA, a large aortic ampulla and mild-to-moderate pulmonary hypertension; the PDA was successfully closed using a Nit-Occlud^® PDA occlusion device (pfm AG, Cologne, Germany). Although this device is frequently used in the pediatric population, adult patients may present different challenges in proper management such as poor visualization, calcification and pulmonary hypertension.^3–5,7

Case Report. The patient is a 68-year-old female with a medical history of a cardiac murmur detected in childhood, overweight, functional class II–III, systemic high blood pressure, hypertensive cardiomiopathy and permanent atrial fibrillation. On physical examination, she had a 2–3/6 continuous murmur at the left infraclavicular region and a second heart sound that was moderately increased in intensity. There was mild-to-moderate cardiomegaly, aortic calcification and increased pulmonary vascular markings on chest X-ray, and the electrocardiogram (ECG) reported atrial fibrillation with no T-wave or ST-segment changes. Transthoracic color Doppler echocardiography showed the following measurements: left atrium (LA) = 51 mm; aorta (Ao) = 43 mm; left ventricular diastolic diameter (LVDD) = 53 mm; left ventricular systolic diameter (LVSD) = 35 mm; interventricular septum (IVS) = 13 mm; posterior wall (PW) = 11 mm; shortening fraction (SF) = 32%; large LA and Ao root; LV hypertrophy with normal SF; and PDA detected by Doppler colormapping of the pulmonary arterial trunk. The patient was unable to bear the probe of transesophageal color Doppler echocardiography, so a diagnostic cardiac catheterization was performed and showed the following: (1) coronary arteries without significant lesions; (2) normal LV systolic function; (3) persistent ductus arteriosus; (4) moderate pulmonary hypertension; (5) an estimated Qp/Qs = 2.
An interventional procedure for ductus closure was scheduled. We selected the Nit-Occlud device due to the fact that the shunt was primarily left-to-right, and according to the Toronto Hospital classification, an anatomic type A is optimal for this device. Pulmonary hypertension was a constant concern, thus we considered the possibility of occluding the ductus with a balloon and monitoring the patient’s pressure. The day before the scheduled procedure, the patient was admitted for signs and symptoms of biventricular heart failure, breathlessness, fatigue and swollen legs. An ECG showed atrial fibrillation with rapid ventricular response, and a chest X-ray showed pulmonary edema and moderate cardiomegaly. Successful medical treatment was administered for 6 days, focusing on negative water balance, diuretics and heart rate control. A new chest X-ray before the postponed interventional catheterization showed evidence of improvement, no pulmonary edema and almost normal cardiac size.

Under local anesthesia, 7 Fr sheaths were inserted in the right femoral artery and vein. Heparin was administered (5000 IU), and right and left standard catheterization showed the following pressures: right atrium (RA) = 10 mmHg; right ventricle (RV) = 65/10 mmHg; main pulmonary artery (MPA) = 56/36 mmHg (m 42); Ao = 142/72 mmHg (m 95); LV = 149/12 mmHg; and the estimated Qp/Qs = 2.9. Using the artery line, we advanced a 7 Fr 4 line wedge pressure balloon catheter (Interventional SA, Buenos Aires, Argentina) with the aid of a Hi-Torque^® Balance Middleweight guidewire 0.014 x 190 cm (Guidant Corp., Indianapolis, Indiana) and passed through the ductus into the pulmonary artery. The balloon was inflated and the catheter was pulled back against the ductus for test occlusion. The patient’s pulmonary pressure was registered through the end-hole of the catheter located in the pulmonary side.We witnessed a drop in pulmonary pressure from 56/36 mmHg (m 42) to 36/25 mmHg (m 28).
After balloon test occlusion, an angiogram was performed in the transverse thoracic aorta with a high-flow pigtail marked catheter (Cook Cardiology, Bloomington, Indiana) in the lateral projection for measurement of the previously confirmed type A ductus (Figure 1). After maneuvers through the ductus due to vasospasm, it looked more like a type D ductus (Figure 2).
Measurement results were 3.2 mm at the narrowest point, and 9 mm at the aortic ampulla, with 8 mm of length. We selected a 11/6 mm Nit-Occlud device from the spiral coil system for PDA occlusion. The system consists of: (1) a 5 Fr introducer sheath with a marker ring at its distal tip; (2) a transportation sheath; and (3) a coil attached to a delivery system of flexible material with 2 marks and a disposable handle for release.

We flushed the system as usual with heparinized solution. With the aid of a 0.035 x 260 cm Wholey floppy wire (Mallinckrodt Inc., St. Louis, Missouri), the introducer sheath was moved across the ductus transvenously and positioned it distally into the descending aorta; the transportation sheath and introducer sheath were connected. We advanced the coil through the transportation and the introducer sheath by pushing the delivery system. At this point, the position of the introducer sheath became unstable and moved back from the aorta to the pulmonary artery. We had to retrieve the coil back into the transportation sheath, disconnect it from the introducer sheath and maneuvers were repeated to reposition the tip of the introducer sheath, this time into the descending aorta near the diaphragm. We advanced the delivery system and configured the first cone of the coil and then, fixing the delivery system to the transportation sheath, we pulled the entire system back until the spirals of the first cone were packed in the aortic ampulla. Although the configuration of the first cone was not done in the usual manner, the device seemed to be fixed.
Knowing that the more material there was in the aortic ampulla the faster it would close, we continued with the configuration of the second cone until reaching the first mark of the delivery system. The second cone was well configured, so we pulled the catheter back over the second mark of the delivery system, configuring the pulmonary side-winding. The gap between the coil and the delivery system was entirely on the pulmonary side, thus we proceeded to release the device. After 5 minutes, angiography showed very little residual shunt (Figure 3). The continuous murmur disappeared while the patient was in the catheterization laboratory. Transthoracic color Doppler echocardiography was performed the day after, and no shunt was detected. The patient was discharged home after an uneventul hospital stay.

Discussion. Percutaneous occlusion is currently the preferred method to treat PDA in adults at several centers.^2,4,5,7,9 This procedure is more often performed in children by pediatric interventionalists. As a result, pediatric interventionalists are more familiar with devices for PDA closure, but it is importantto consider that adult patients may present different challenges. In this case report, for example, we encountered tortuous femoral vessels, dilated great vessels, poor visualization with a large amount of contrast media compared to pediatric patients, aortic calcification and chronic arrhythmia — all conditions that are not typically present in children.^4,5,7 Cooperation therefore between adult and pediatric interventionalists is a must in these cases.
The device selection, a Nit-Occlud in this case, was based on two important factors, the first of which was the patient’s type- A ductus according to Toronto Hospital’s anatomic classification, although after maneuvers, it looked more like a type-D ductus.⁶ This device was originally designed for a type-A ductus (approximately 70% of all ductus are type-A), with a wide aortic ampulla and a narrow-diameter pulmonary artery. The Nit-Occlud could also be considered for other types of ductus which are less frequently found (types B, C, D and E) as long as the narrowest diameter measures 6 mm or less. The Nit-Occlud has also been used lately in the treatment of other types of defects such as coronary fistulae.¹² The device consists of a nitinol coil over two positioned cones and is offered in three models: (1) Flex: 4 x 4 mm, 4 x 5 mm and 4 x 6 mm; (2) Medium: 7 x 6 mm, 9 x 6 mm and 11 x 6 mm; and (3) Stiff: 10 x 6 mm, 12 x 6 mm and 14 x 6 mm. We selected the medium 11 x 6 mm device because of its length and flexible spiral. The fact that the first cone configured itself like the “tower of Pisa” and packed itself in the ductus ampulla was a great advantage. The second cone was well configured and the gap was entirely on the pulmonary side. Delivery and released of the device were successful.
The second important factor we considered was the presence of a primarily left-to-right shunt and the absence of significant pulmonary hypertension in our patient. Moderate-to-severe pulmonary hypertension can jeopardize this procedure, and stabilizing this device, as with many others, can be challenging. This has led interventionalists to use devices not specially designed for ductus repair, with double disks to ensure stabilization and avoid probable embolization, as well as devices designed for auricular septal defects, especially with type-B ductus.^4,6,7 Although some interventionalists may disagree with the method we employed to occlude our patient’s ductus, we felt that inflating a balloon that would stretch the ductus ampulla in a calcified aorta of a 68- year-old woman could cause tissue laceration and endothelial dissection. In this case, moderate pulmonary hypertension, a Qp/Qs of 2 and a positive occlusion test with a monitored drop in pulmonary pressure were all positive arguments for the selection of this device.
In conclusion, adult patients with a type-A ductus may benefit from percutaneous occlusion using the Nit-Occlud PDA device. An occlusion test balloon demonstrating low pulmonary pressure must be performed in these cases. For larger ductus, the presence of pulmonary hypertension or other ductus types (B, C, D and E), the Stiff Nit-Occlud model, or other devices, should be considered. Furthermore, it was both crucial and exciting to involve both adult and pediatric interventionalists in the treatment of this adult PDA patient.

References

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