Implanting the Duct Occluder
Perform a right heart catheterization in routine fashion. There are two options for angiographic demonstration of the patent ductus arteriosus. The first is to introduce an exchange guidewire through the ductus and pass a pigtail catheter with side holes in the communication. Perform a biplane angiogram to opacify the PDA (Figure 1). The second option is to pass a pigtail catheter into the proximal descending aorta via the femoral artery and perform the biplane angiogram to opacify the PDA (Figure 2).
Angiographic appearances of the patent ductus arteriosus are classified according to the categories that Krichenko et al 1 previously described. Figure 3 lists the 9 types of PDAs.
Select an AMPLATZER® Duct Occluder based on the smallest diameter measured in the PDA (refer to Figure 4 “B” measurement). It is recommended to select a device so that the smaller end of the device is at least 2-mm larger than the narrowest portion of the PDA. The device size is a two-digit number. For example in the 8/6 device, the 8 refers to the diameter inside the retention skirt of the device, and the 6 refers to the opposite smaller end of the device. If the “B” measurement in the ductus is 4 mm, select the AMPLATZER Duct Occluder with the smaller end of at least 6 mm. Therefore, the 8/6 device would be selected.
Introduce an exchange J-tipped guidewire. Remove the catheter. Advance the introducing sheath with dilator over the exchange wire into the aorta and position the sheath in the descending aorta while removing the dilator. (Figure 5). Position can be confirmed by a test injection of contrast medium.
Pass the delivery cable through the loader and screw the AMPLATZER Duct Occluder clockwise onto the tip of the delivery cable (Figure 6).
Immerse the device and the loader in saline solution and pull the AMPLATZER Duct Occluder into the loader.
Introduce the loader into the delivery sheath and without rotation, advance the device into the descending aorta (Figure 7).
Deploy the retention skirt only and pull firmly against the orifice of the patent ductus arteriosus. This can be observed by fluoroscopy, or it can be clearly felt as a tugging sensation in synchrony with the aortic pulsation. The position of the device is confirmed with repeated angiograms in the aorta using the pigtail catheter. The device can be adjusted until the retention skirt is well seated in the ampulla. Retract the delivery sheath and deploy the cylindrical portion of the device securely in the patent ductus arteriosus while applying slight tension (Figure 8).
Perform an aortogram to verify correct position of the device. Perform and record on cine a power injection through the catheter using 1 cc per kilogram of contrast at 12 ml per second at 400 psi. To have optimal visualization of the anatomy, angulate the AP camera at 35 degrees LAO and 35 degrees cranial, and the lateral camera straight. These views will allow you to delineate the length of the device protruding into the pulmonary artery lumen.
WARNING: Remove the device if >3mm extends into the pulmonary artery, or if more than half of the left pulmonary artery lumen is occupied by the device. In questionable cases, perform transthoracic echocardiography before release of the device with Doppler measurement of left pulmonary artery flow velocity. The device should be removed if left pulmonary artery flow is >3.0 m/s (or >75% greater than the LPA velocity before cardiac catheterization).
If position is not satisfactory, recapture the device into the sheath by pulling back on the delivery cable.
NOTE: Do not release the device from the delivery cable if the device does not conform to its original configuration or if device position is unstable. Recapture the device and redeploy. If still unsatisfactory, recapture the device and replace with a new device.
Screw the plastic vise on the delivery cable and detach the device by rotating the cable counter clockwise as indicated by the arrow on the vise. (Figure 9). Repeat aortogram.
Footnote:
1. 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 of Card 1989;63:877-80.