YOUR DOG - TUFTS UNIVERSITY SCHOOL OF VETERINARY MEDICINE: NEW HELP FOR HEART DISEASE
Coils and balloons correct congenital defects
When Christine Brito wanted a second Bichon Frise, the breeder offered her 5-month-old Annabelle for free. The catch: The puppy had been born with a common heart defect – patent ductus arteriosus. Unless she underwent a new high-tech operation, she would live only a year or two.
Although the procedure is costly--$2,000 to $3,000—it would give Annabelle the chance for a long, full life. Brito of Framingham, Mass., agreed and took the puppy home to play with her other Bichon. There, Annabelle tired quickly and became breathless.
After listening to Annabelle’s heart and hearing a continuous heart murmur, or turbulence in the flow of blood through the heart, her veterinarian followed up with a chest X-ray and evaluation of her heart on an echocardiogram. He confirmed Annabelle’s PDA.
Now thanks to new scientific equipment and procedures performed by veterinary cardiologists at Tufts University School of Veterinary Medicine and other veterinary hospitals, there is hope for dogs like Annabelle who have certain types of congenital heart disease—patent ductus arteriosus and pulmonic stenosis.
Veterinarians use high-tech catheters to place coils and insert balloons for valvuloplasty to alleviate these conditions. These also implant cardiac pacemakers in dogs with slow or irregular heart rates.
No Smooth Muscle
PDA occurs when the ductus arteriosus—a vessel permitting blood to bypass the lungs, which are nonfunctional in a fetus—does not close automatically at birth. The ductus lacks smooth muscle in the vessel wall to enable it to close. Because it remains open, the blood continues to flow, or leak, from the aorta through the open vessel and into the pulmonary artery. To compensate for the leak and provide a normal blood flow to the body, the left side of the heart must work harder to pump more blood.
“To repair this condition before the coil and balloon valvuloplasty techniques were available, veterinary cardiologists routinely opened the chest and made an incision into the chest cavity to tie off the vessel. Surgical closure of the patent ductus is sometimes difficult for the dog to endure. Recuperation is long, but today veterinarians at the Tufts University School of Veterinary Medicine and other schools have another option and an easier way to close the ductus.
“Now we use a coil technique, which avoids having to open the chest,” says James Ross, DVM, professor of cardiology at Tufts. “We insert a catheter in the vascular system through an artery in the leg and guide a coil, which is a tiny spring-type device covered with a material that induces blood clotting, up through the aorta to the ductus.”
The size of the coil depends upon the size of the dog. Cardiologists conduct diagnostic tests to measure the ductus’ diameter and anatomy. If it doesn’t have a long enough piece of blood vessel for the coil to lodge in, a dog would not be a candidate for the coil procedure.
We have to position the coil inside the ductus arteriosis, and sometimes it takes several coils during that same procedure to block that vessel,” Dr. Ross says. Once the dog is anesthetized, the coil procedure takes about 45 minutes to an hour and a half to complete.
“There is an excellent chance of recovery with the coil procedure,” Dr. Ross says. “Although there are risks of anesthesia, perforating the blood vessel or the coil dislodging at the time of placement or just right after, the incidence of terrible reactions is low.”
After the coil was inserted in Annabelle’s heart at Tufts, her heart healed completely and she’s as good as new. She has a lot more stamina and seldom pants.
It’s better to correct a congenital heart problem as early as possible in a dog’s life. “Many dogs are diagnosed with PDA when they are between 4 and 5 months of age, and the correction can be done when the dog is 6 to 9 months old,” says Rebecca Gompf, DVM, Diplomate of the American College of Veterinary Internal Medicine, at the University of Tennessee.
Remainder of article available upon request.