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A Life Saving Cardiac Procedure for Sage
The owners of a 6 month old female Labrador puppy, Sage, contacted Dr Singh as she had been recently diagnosed with a Patent Ductus Arteriosus (PDA)

A Life Saving Cardiac Procedure for Sage

The owners of a 6 month old female Labrador puppy, Sage, contacted Dr Singh as she had been recently diagnosed with a Patent Ductus Arteriosus (PDA). The owners were told that that Sage would have to fly to the East Coast to have her heart disease corrected. Luckily for her, the owners chose to do some research and contacted Dr Singh directly. Dr Singh and her team immediately arranged evaluation of the puppy in order to confirm and co-ordinate the best treatment plan for Sage.

On evaluation, Sage was bright and alert. The owners had not reported any signs of fatigue or respiratory signs. Sages heart rate was 100 beats per minute and regular. She had a grade 5/6 continuous murmur heard under her left armpit. A continuous heart murmur is one in which turbulent blood flow can be heard in both phases of the cardiac cycle (systole and diastole). This type of murmur is very suggestive of a PDA.

What is Patent Ductus Arteriosus?

In the developing foetus, blood entering the right heart is already well oxygenated as it is coming via the mother’s placenta. Hence, blood does not need to pass through the foetus’s lungs to pick up oxygen. There are a number of mechanisms in place that allow the blood to bypass the lungs in the foetus. One of these is a vessel called the ductus arteriosus. The ductus arteriosus is a small vessel that connects the pulmonary artery (the vessel that takes the blood to the lungs) to the aorta (the vessel taking oxygenated blood to the body).  The ductus arteriosus should start to close at birth and is normally completely closed by 3 days. Occasionally this does not happen and the ductus arteriosus remains open or ‘patent’.

Once born, blood flows from the high pressure aorta to the low pressure pulmonary artery, to the lungs and back to the left side of the heart. Over time, the extra blood flow to the lungs and left heart causes these chambers to increase in size. If left uncorrected, congestive heart failure (fluid in the lungs) is the result. In 65% of dogs congestive heart failure will occur by 12 months of age.

An echocardiogram confirmed that Sage did indeed have a PDA and her heart was already starting to become significantly enlarged from the extra blood flow. Hence, correction as soon as possible was advised.

How is a PDA Treated?

Surgery was the traditional method of PDA repair. In a PDA surgery, the chest is opened, the PDA carefully dissected free from the surrounding vessels and a piece of suture is used to tie off the patent vessel.  This surgery requires a specialist surgeon with complication rates of < 10% in experienced hands. With the increasing availability of specialist Veterinary Cardiologists, a non-invasive method of correction is preferred. In this method, a small nickel-titanium plug (called an Amplatz Canine Ductal Occluder) or a smaller metal coil is delivered via a catheter to plug up the PDA. The catheter is usually delivered via the femoral artery.  Minimally invasive occlusion has the advantage of not having to open the chest. Hospital stay and postoperative medications are minimized with this approach, however, it is often not feasible to use this approach in very small puppies due to the small size of their femoral artery.  In this situation, open chest surgery may be recommended.

Sage went on to have the minimally invasive occlusion performed by Dr Singh. Her PDA is now completely plugged up, her heart has returned to a normal size and Sage will go on to live a normal life.

Do you have a puppy with a heart murmur?

If you have a puppy with a heart murmur, it is essential to have this evaluated by a Veterinary Cardiologist as soon as possible. Many times, the heart murmur is innocent and no treatment is required. However, on the occasion that there is something more serious going on, receiving the correct diagnosis and treatment plan is the best way to ensure your puppy lives a long, healthy life.