Patent Ductus Arteriosus

Rebecca E. Gompf, DVM, MS, DACVIM (Cardiology)

BASIC INFORMATION completed all of the puppy vaccinations. Closure of the PDA is Description usually done by a specialist in veterinary surgery or cardiology. Patent ductus arteriosus (PDA) is a congenital heart defect. Prior Surgically tying the PDA closed is the oldest method of treat- to birth, all mammals have a blood vessel (ductus arteriosus) that ment. It is used in puppies that are too small to be catheterized or connects the two main arteries leaving the heart, the aorta and the that have a PDA with a shape not easily closed by other methods. pulmonary artery (to the lungs). The ductus arteriosus allows the Surgery involves opening the left side of the chest under general blood to go from the pulmonary artery into the aorta, bypassing anesthesia. the lungs, because the fetus is not breathing yet. Less invasive methods of closing PDAs also require anesthesia After the animal is born and starts to breath on its own, the ductus and insertion of a catheter into the heart. Coils or a special plug arteriosus normally closes. In 2 or 3 of every 1000 dogs, it does not (Amplatzer ) may be placed in the opening of the PDA to occlude close and is called a PDA . In these animals, some of the blood flows (block) it. These methods require the presence of veins and arter- from the aorta through the PDA into the pulmonary artery and the ies large enough to accommodate the special catheters used for lungs, then back to the left side of the heart. This extra blood flow these procedures. overloads the left heart and eventually causes left heart failure. Causes Follow-up Care The ductus may not close because the muscle that causes the sides Following open-chest surgery, the animal is usually hospitalized to contract, collapse, and fuse is lacking. In many breeds of dogs for a few days and then must be kept quiet until the incision heals. this defect may be inherited, so affected dogs should not be used Sutures can be removed in 10-14 days by your veterinarian. for breeding. PDA is one of the most common congenital defects Following closure by coils or an Amplatzer plug, the animal found in dogs. It is uncommon in cats. must also be kept quiet for a few days to allow the rear leg vessels, where the catheter was inserted, to heal. If sutures were placed in Clinical Signs the rear leg, they are removed in 10-14 days. Most puppies with PDA have no signs, and the murmur caused If the animal was in heart failure prior to PDA closure, medi- by the PDA is discovered when the puppies are examined by a cations may be continued long term, and periodic monitoring is veterinarian. Occasionally a puppy has such a large PDA that it required. If heart failure was not present, most dogs need no fur- dies before weaning. If left heart failure occurs, breathing rate and ther monitoring once their sutures are removed. effort are increased. Coughing, lethargy, and failure to gain weight Prognosis may also be noted. Prognosis is excellent in dogs that are not in heart failure and do not have atrial fibrillation. Success rates with surgery or catheter Diagnostic Tests occlusion are 90-95%. Most of these dogs have a normal life span If your veterinarian discovers a murmur suspicious for PDA, chest and few complications. Complications of surgery include death, x-rays and an echocardiogram (heart ultrasound) will be done to which usually occurs when the PDA ruptures while being dis- confirm the diagnosis and to determine the size of the left heart sected. Occasionally, ligatures can slip and break after surgery, and how well it is functioning. Blood tests may be done prior to which necessitates a second procedure; this tends to occur in older anesthesia. dogs. Complications of coil placement include dislodgement and TREATMENT AND FOLLOW-UP movement of the coils into the lungs. Occasionally, the coils do not close the PDA completely, which may or may not cause future Treatment Options problems. If the animal is in heart failure or has an abnormal heart rhythm Complications of Amplatzer occlusion are uncommon, but (atrial fibrillation), treatment is required prior to anesthesia and some PDAs cannot be closed by them. With any catheter pro- surgical correction. If the heart has not been affected much by cedure, swelling may develop at the site where the catheter was the PDA, surgery may be delayed until the pup is larger and has inserted into the leg.