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 Patent Ductus Arteriosus (PDA): A Parent's Guide


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Patent Ductus Arteriosus (PDA): A Parent's Guide

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How is a PDA treated?
There are several treatment strategies for a PDA. The treatment that is best for any individual child depends on several factors, the most important of which is the child's age.

Premature Infants: Most children who become seriously ill with congestive heart failure in the newborn period are premature infants in whom the ductus does not close at all. There are two treatment options for these babies.

1. Indomethacin Therapy: This is a medication that is in the same class of drugs as aspirin and ibuprofen (Non-Steroidal Anti-Inflammatories). The indomethicin (sometimes called "indocin") works by indirectly stimulating the muscles of the ductus to contract. This medicine works in a large percentage of premature infants. As with any other medication, indomethicin has side effects which may include internal bleeding and kidney dysfunction. In many babies, treatment with indomethicin may be repeated if the first course is not successful, and if there are no side effects.

2. Surgical Therapy: If indomethicin is ineffective, or if the child cannot receive the medication due to other medical problems, surgical treatment of the PDA is indicated in almost all cases. The first surgical closure of PDA was accomplished in 1938. The transcatheter techniques that will be described below are not generally applicable in premature infants due to the small size of the heart and blood vessels.

With the baby under general anesthesia, the surgeon enters the chest from under the left arm, and isolates the PDA. If the PDA has enough length to it, the optimal surgical technique is to tie a suture (or place a surgical staple) around the PDA at both ends, and to cut the PDA between the two sutures. This prevents the PDA from re-opening later on. In some cases, the PDA is very short. In these newborns, the surgeon may only be able to fit a single suture. A surgical series from Scandinavia reported up to a 20% recurrence rate with this technique. Surgical closure of PDA is very reliable, has few complications, and is safe in even the smallest premature infants.

Infants and Children with PDA: It is rare for full term infants, or for older children to have congestive heart failure symptoms from a PDA, though it certainly can occur. Similar to the premature infants, there are significant size issues in children less than 6 months of age, especially those who are growing poorly due to congestive heart failure. Many institutions prefer the surgical option for children under 6 months of age who have signs of heart failure. For children older than 6 months who are otherwise well, surgery has been virtually eliminated due to successes with the newer transcatheter closure techniques.

Transcatheter Closure of PDA: There have been many devices developed for the closure of a PDA without surgery. These devices date back to the early 1970's when Dr. Porstmann first described such a device. This device was extremely bulky and carried very high complication risks. Since that time, several other devices have been developed for the purpose of closing the PDA.

Rashkind Device: The first device to gain widespread popularity was developed by Dr. William Rashkind. Though never approved by the FDA for use in the United States, the device is still in use in other countries. This device is made up of two tiny sponge umbrellas which are attached to one another. When positioned correctly, the device "straddles" the PDA, with one umbrella on the aortic side of the PDA and one on the pulmonary artery side. The size of each umbrella is larger than the orifice of the PDA, so the device cannot move. The umbrellas become coated with blood and quickly become non-porous. Eventually the natural tissue lining of the blood vessels grows to cover the device so that blood travelling past it does not "know" it is there.

This device was quite successful in closing small PDA's (> 90% success rate), but was limited by the large catheter sizes required for delivery. This precluded its use in small children. The device was removed from trials in the U.S. in 1992.

Coil Occlusion Techniques: In 1992, with the Rashkind device unavailable for closure of PDA's, Dr. John Moore first described the technique of closing a PDA with a device called a Gianturco coil.

The coil is essentially a spring made of surgical steel which is imbedded with dacron fibers over its entire length. The coil has been in clinical use since 1972, and has a long record of successful closure of other blood vessels (bleeding ulcers, brain tumors, etc.). It was only in 1992 however, that the coil was first applied to a PDA.
The principle of the coil is similar to that of the Rashkind device. The coil loops are larger than the size of the PDA opening. Once loops are placed on each side of the PDA, the spring holds it in position while the dacron fibers allow formation of a clot which eliminates flow through the PDA. The coil is then covered by the vessel lining, as is the case with the Rashkind device.

In contrast to the Rashkind device, the coil can be delivered through a catheter as small as 1.3 mm in diameter (4 French catheter), can be done in small babies, and is usually done as an outpatient procedure. The coil procedure has achieved success rates of over 95% in most series. This procedure has gained extraordinary world-wide support in a very short period of time.

There have been several techniques described for coil delivery, each of which has its own set of advantages and disadvantages:

1) Transarterial approach: The original method of Dr. Moore. A single catheter is placed in the artery of the leg, and advanced to the chest to deliver the coil. With this technique, the most significant risks in early publications related to coil positioning. With no reliable method for repositioning or removing the coil, inaccurate placement lead to incomplete closure, and "embolization" of the coil into the lungs (an unstable coil may be pushed out of the PDA by the force of the blood flow trying to get through) in up to 15% of early procedures. As the catheterizing physicians became more experienced, the risk of losing the coil into the lungs decreased. Larger PDA's were too difficult to attempt closure with this original technique. With a catheter in the artery, a very small percentage of children, particularly those under 10 kg, had complications involving the circulation to the leg, a transient problem.

2) Transvenous approach: Originally described by Dr. Ziyad Hijazi, in this technique the artery is not used. Rather the catheter(s) are introduced through the vein in the leg, avoiding any potential complications with the artery. While not using the artery was seen as an advantage, this technique was originally criticized for the increased potential to lose the coil into the aorta, with the potential for blocking flow to a vital structure (kidney, leg, intestinal artery, etc.). This was an infrequent complication.

3) Snare-assisted delivery: This technique, developed by Dr. Robert Sommer, uses a special snare catheter (a catheter with a cowboy's lasso on the end of it) to hold the coil while it is delivered. This allows precise positioning and repositioning of the coil (if necessary), resulting in higher closure rates. It allows for the testing of the coil stability in the PDA prior to release, and as a result, eliminates the complications of coil "embolization", in which the coil is pushed by the blood flow out of the PDA to the lungs. This complication occurred in as many as 15% of cases in early series. The use of the snare has been criticized as an unnecessary cost in patients with small PDA's.

4) Retrievable coil techniques: Special coils are used which can be detached only when they are stable in the proper position. These coils, while less likely to embolize, also seemed to have lower rates of complete closure. Newer versions of these coils are soon to be on the market.

5) Grifka-Gianturco "bag": For larger PDA's that were not ideal for coil closure, Dr. Ron Grifka developed a "bag" attached to the end of the catheter into which the coils are placed. This technique has been very successful, but is only applicable in PDA's with substantial length.

6) 0.052 inch coils: Dr. Phillip Moore first described the use of thicker coils for the closure of larger PDA's. The principle of using a thicker coil was that it would take up more space within the PDA, and would therefore obstruct blood flow more effectively within the PDA. This has been quite successful in closing larger PDA's.

7) Latson Catheter: Dr. Larry Latson has developed a delivery catheter which allows for reliable coil removal and/or repositioning (similar to the retrievable coils) in the event that the coil is not optimally straddling the PDA.

Still other, newer devices are being developed for closure of the PDA. None are yet approved for general use by the FDA, but some have started testing in the U.S. and abroad.

Any technique that can be used in older children is equally applicable to the rare adult patient diagnosed with a PDA. We have used the coil occlusion technique in adults up to 76 years of age, when they presented with symptoms for the first time in adulthood.

The specific technique of transcatheter PDA closure that is best for your child depends on the PDA size and shape, the size of your child, and the techniques with which your pediatric cardiologists are most comfortable.

Surgical Techniques

Traditional Surgical Approach: An incision 5-7cm in length is made and the chest is entered by spreading the fourth and fifth ribs apart. The PDA is then identified by clearing away the surrounding tissue, taking care to avoid injury to the nerves which go to the voicebox and the diaphragm (the phrenic nerve). A stitch is then tied around the PDA on both the aortic end and the pulmonary artery ends of the ductus (ligation), which is then cut in the middle (division) if there is enough length. Ligation and division yields the lowest incidence of recurrence (<1%).

Thoracoscopic Approach: Several centers have published series in which a small telescope is used to guide the surgical closure of the PDA. In the thoracoscopic approach, two or three smaller incisions (1cm) are made to facilitate the imaging and surgical equipment, rather than the single larger incision of the traditional approach. The results are comparable to the standard thoracotomy approach that remains the gold standard. This technique, however, requires special equipment and surgical training not available at most centers, and seems to offer few advantages over traditional surgery.

Muscle Sparing Thoracotomy: Newer techniques for cardiac surgery have resulted in the miniaturization of instruments and have allowed significant reduction in the size of the surgical incision. These "muscle-sparing" or minimally invasive techniques have resulted in faster patient recovery times and shorter hospitalizations. In some centers, these surgeries are being done on an ambulatory basis. Regardless of the surgical approach, hospital stays are seldom more than overnight.

Summary
The diagnosis of Patent Ductus Arteriosus (PDA) is relatively common, affecting 1 in 2,000 children. While the majority of children do not have symptoms, the risks are nonetheless real. It is comforting for parents to know that no matter which technique is employed for treating this problem of their child's heart, after closure of the PDA, the circulation is normal, and the child will have a normal heart with no further risks for the remainder of a normal life.


This article was reviewed prior to publication by:

Lucian A. Durham, III, M.D., Ph.D.
Director, Pediatric Cardiovascular Surgery
Strong Children's Heart Center
University of Rochester Medical Center

William B. Moskowitz, M.D.
Director of Pediatric Cardiac Catheterization Laboratory
Medical College of Virginia

Parent/ACHD Reviewers:
Wanda and Ray Tinetti
Leah Weinstein


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