Ultrasonic Guidance for Percutaneous Closure of Patent Ductus Arteriosus in an Adult

From the Division of Cardiology, Sharp Rees-Stealy Medical Group and Sharp Memorial Hospital, San Diego, California. The authors report no conflicts of interest regarding the content herein. Manuscript submitted February 24, 2009, provisional acceptance given March 23, 2009, and final version accepted March 30, 2009. Address for correspondence: Reinaldo Beyer, MD, 2929 Health Center Drive, Cardiology Suite 2nd floor, Sharp Rees-Stealy Medical Office Building, San Diego, California 92123. E-mail: reinaldo.beyer@sharp.com

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J INVASIVE CARDIOL 2009;21:E141-E144 Since the initial report by Porstman, several different devices have been used to percutaneously close a patent ductus arteriosus (PDA).1 One of the most frequently used devices is the Amplatzer occluder (AGA Medical Corp., Plymouth, Minnesota).2 The most commonly encountered morphologic features of a PDA are well matched by that device. The technique requires definition of the morphology, sizing of the key features and monitoring of the position and deployment of the device. These are usually achieved by fluoroscopy and aortography to image the PDA itself.2 Like any planar radiographic imaging, aortography with injection at the mouth of the PDA suffers from magnification distortion related to the distance of the imaged object from the source and image intensifier. There can also be pincushion distortion, depending on the location of the measured image within the field. Planar imaging requires perpendicular views in order to understand the three-dimensional position and shape of a structure. Monitoring the deployment requires repeated acquisition of images with repeated contrast injections. We sought to obviate some of these difficulties by adding to the X-ray images phased-array ultrasound imaging obtained with the AcuNav™ (Biosense Webster, Inc., Diamond Bar, California) catheter inserted into the descending aorta. Its features have been well described.3 Briefly, the tip of this solid 8 Fr or 10 Fr catheter has a longitudinally placed transducer that allows imaging in a 90 degree standard echocardiographic sector. The tip with the transducer can be deflected up to 160 degrees in four directions along two perpendicular planes by control knobs. We attempted to define the morphology and size of our patient’s PDA and to monitor the deployment of the occluder device with the AcuNav system. Case Presentation. An asymptomatic 38 year-old female presented to our clinic after a murmur was heard on a routine preventive physical examination. A loud continuous machinery-type murmur peaking at the second heart sound was present in the left infraclavicular area. The electrocardiogram (ECG) was normal. A transthoracic echocardiogram (TTE) showed left atrial enlargement. A high-velocity jet was noted in the pulmonary artery on color Doppler. Continuous flow was confirmed by CW-Doppler, with the highest velocity in late systole. Cardiac catheterization demonstrated a Type A PDA by aortography, no stenoses in the coronary arteries, but an anomalous circumflex arising from the right coronary artery and traveling behind the aorta. The patient’s pulmonary artery pressure was 31/13 mmHg. Her oxygen saturations were: 82.3% mixed venous (superior vena cava 81.9%, inferior vena cava 83.4%) mid-right ventricle 82.7%, main pulmonary artery 88%, pulmonary wedge 99%, ascending aorta 98% and descending aorta 97.9%, resulting in a left-to-right shunt ratio of 1.4. After reviewing the information with the patient and her family, percutaneous closure of the PDA was proposed. Given our prior experience with the AcuNav intracardiac echocardiogram system and our experience with transesophageal echocardiography (TEE) specifically in PDA closure, written informed consent for use of intra-arterial AcuNav and PDA closure was obtained. Under local anesthesia and mild sedation, right and left femoral artery and right femoral vein access was obtained using the Seldinger technique. A bolus of 0.75 mg/kg bivalirudin and then an infusion at 1.75 mg/kg/hour were used for anticoagulation. A 5 Fr multipurpose catheter was advanced over a wire into the right heart chambers and a 5 Fr marked pigtail into the aortic arch from the right femoral artery. An 8 Fr AcuNav catheter from the left femoral artery was advanced into the descending aorta and positioned at the level of the origin of the left subclavian artery (Figure 1). An aortogram injecting iodixanol (Visipaque) at 20 mL/s for 2 seconds in the left lateral projection was filmed. The Type A PDA was clearly seen (Figure 2). The PDA was imaged using the AcuNav catheter connected to a Cypress ultrasound system (Siemens Corp., New York, New York) at a frequency of 6.0 MHz. From the resting position with all marker ridges directed anteriorly (i.e., catheter straight and the imaging surface facing anteriorly), slight counterclockwise rotation revealed a funnel-like structure. Doppler imaging confirmed flow in the structure and was also helpful in confirming a structure as vascular throughout the procedure. Further advancement of the AcuNav catheter and anterior flexion allowed imaging of the length of the PDA and its connection with the pulmonary artery. The image of the left main bronchus was a useful landmark for this, with the PDA being superior and its aortic origin slightly posterior to the bright echogenic image of the left bronchus (Figure 3). The length, aortic opening diameter and pulmonary opening diameter of the PDA were then measured using both the AcuNav system and aortography. A minimal PDA diameter of 6 mm at the pulmonary artery opening was obtained by ultrasonography, and this was confirmed by the aortogram. The procedural technique, the device itself and the clinical results with the Amplatzer duct occluder have been well described.2,4 An Amplatzer device with a diameter of 10 mm at the aortic end and 8 mm at the pulmonary end (length 8 mm) was selected. The PDA was crossed with a wire and multipurpose catheter, then an exchange wire was placed in the descending aorta. This maneuver could be clearly visualized by the AcuNav system (Figure 4). A 7 Fr 180 degree TorqVue catheter was advanced over the wire into the descending aorta. The Amplatzer occluder was then advanced and deployed in the usual fashion,2,4 with both fluoroscopic and ultrasonographic guidance throughout this process (Figure 5). Once good positioning and expansion of the device were observed by the AcuNav system, a repeat aortogram was filmed (Figure 6) and the device released. Bivalirudin infusion was stopped. All catheters were then removed and hemostasis achieved by manual pressure after checking the patient’s activated clotting time (ACT). On follow up 1 month later, the occluder was in good position and the abnormal jet into the pulmonary artery had disappeared by TTE with Doppler flow imaging. Discussion. A patent ductus arteriosus typically courses from the aorta, opposite to and just beyond the left subclavian artery to the left side of the bifurcation of the main pulmonary artery, adjacent to the left pulmonary artery. Most commonly, the channel is funnel-shaped, with the aortic orifice being wider than the pulmonary artery orifice (Type A PDA).5 TTE imaging of a patent ductus has been described in children specifically to assess the morphologic features necessary to plan percutaneous closure.6 In adults TTE is unlikely to penetrate adequately to allow for the image quality needed for such an assessment. Suprasternal imaging, in which a patent ductus appears as a narrow channel connecting the inferior aortic border to the pulmonary trunk, can also be limited in adults. In adults the main finding in the TTE, especially with a small defect, is the retrograde jet of high velocity in the pulmonary artery noted by color Doppler. From our prior experience, TEE is difficult and particularly cumbersome to use during a PDA closure. Localizing and visualizing the PDA was more tedious and time consuming than with the AcuNav catheter. The probe position obstructs the operators view on fluoroscopy, necessitating frequent withdrawals and reinsertions of the probe to visualize the area of interest. Imaging is largely dependent on identifying the color-Doppler high-velocity jet flowing into the pulmonary artery, and a complete image of the walls of the PDA is very difficult to obtain. General anesthesia and an additional operator are required for TEE, adding logistic difficulties to its use. Intracardiac echocardiography with the AcuNav catheter is a well established imaging procedure for guidance on cardiac interventions. It is performed with the ultrasound catheter placed in the right heart.7 In an adult patient with a PDA, the distance from the right atrium will approach the maximal imaging depth obtainable with the AcuNav system. Imaging with the transducer placed in the pulmonary artery may be feasible, but closure of the PDA requires an additional catheter in the pulmonary artery. Arrhythmias with two catheters across the right ventricular outflow tract are likely. The position of the imaging catheter is not likely to be stable, particularly with manipulation of the occluder delivery catheter immediately adjacent to it. On the other hand, and as we report here, imaging from the aorta required only slight manipulation of the catheter, its position remained stable during the procedure and it was well tolerated. The disadvantage of arterial insertion of the AcuNav catheter without the benefit of a guidewire could be mitigated by first inserting a long sheath into the descending aorta. A report using a 10 Fr AcuNav introduced with a long arterial sheath to image Type B aortic dissection found no catheter-related complications, but recommended caution handling the catheter.8 We believe that anticoagulation is prudent. The images obtained with the AcuNav system in our case were very useful in characterizing and sizing the PDA. The left main bronchus was a good landmark for imaging and precisely positioning the catheter. Monitoring the wire passage and occluder deployment by ultrasonography in addition to fluoroscopy was of great help and relatively easy to perform, increasing our confidence in the correct sizing and placement of the occluder. The only manipulations of the AcuNav catheter needed were first a slight counterclockwise rotation from the resting position in which the transducer faces anteriorly at the level of the left subclavian (Figure 1). This allowed visualization of the aortic opening of the PDA. The next maneuver of the AcuNav involved slight advancement and anteflexion to image the PDA in its length, with better definition of the tube-like structure (Figure 3). We found that after this maneuver, returning to the initial position by straightening the AcuNav and slight withdrawing of it to face the aortic opening gave better views of the occluder position in the aortic funnel of the PDA (Figure 5). We could have obtained better resolution by a frequency higher than 6 MHz, since the structures to visualize were close to the transducer. AcuNav offers an additional plane of imaging compared to fluoroscopy and aortography alone. Characterization of the shape of the PDA and precise sizing are relatively easy if the proper imaging plane is obtained and the PDA is closed as is usually done with the Amplatzer device via the pulmonary artery. We believe this may reduce the amount of radiation and contrast injections and improve the safety and reliability of PDA percutaneous occluder procedures in adults. The drawbacks are, first, the retrograde insertion of an 8 Fr catheter into the arterial system without a wire to guide it, and second, the risk of catheter-induced thrombosis in the arterial catheter. Both of these problems can be overcome by proper catheter manipulation techniques, use of a long sheath and systemic anticoagulation. Conclusion. Imaging with the 8 Fr AcuNav catheter system used retrogradely from the femoral artery into the descending aorta can be utilized for anatomical characterization and sizing of a PDA in adults. Monitoring of occluder deployment is easily accomplished, and anticoagulation is probably prudent.

2. Masura J, Walsh KP, Thanopoulos B, et al. Catheter closure of moderate-to-large-sized patent ductus arteriosus using the new Amplatzer duct occluder: Immediate and short-term results. J Am Coll Cardiol 1998;31:878–882.

3. Bruce CJ, Nishimura RA, Rihal CS, et al. Intracardiac echocardiography in the interventional catheterization laboratory: Preliminary experience with a novel, phased-array transducer. Am J Cardiol 2002;89:635–640.

4. Wang JK, Wu MH, Hwang JJ, et al. Transcatheter closure of moderate to large patent ductus arteriosus with the Amplatzer duct occluder. Catheter Cardiovasc Interv 2007;69:572–578.

5. Krichenko A, Benson LN, Burrows P, et al. Angiographic classification of the isolated, persistently patent ductus arteriosus and implications for percutaneous catheter occlusion. Am J Cardiol 1989;63:877–880.

6. Ramaciotti C, Lemler MS, Moake L, Zellers TM. Comprehensive assessment of patent ductus arteriosus by echocardiography before transcatheter closure. J Am Soc Echocardiogr 2002;15:1154–1159.

7. Liu Z, McCormick D, Dairywala I, et al. Catheter-based intracardiac echocardiography in the interventional cardiac laboratory. Catheter Cardiovasc Interv 2004;63:63–71.

8. Bartel T, Eggebrecht H, Mueller S, et al. Comparison of diagnostic and therapeutic value of transesophageal echocardiography, intravascular ultrasonic imaging and intraluminal phased-array imaging in aortic dissection with tear in the descending thoracic aorta (type B). Am J Cardiol 2007;99:270–274.