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Penny: Cutting Balloon Valvoplasty

by Dr. Scansen, OSU

 

From Dr. Brian Scansen

As always, it was my pleasure to work with the NCA to help Penny. I am comforted and inspired knowing that there are organizations such as the NCA, and their Charitable Trust, who work to improve the lives of dogs in need. Penny’s case was a challenge as her disease was advanced at a relatively young age. However, she was a bundle of black furry joy throughout her hospitalization and recovered beautifully. I remain hopeful that this treatment option will provide her improved survival and comfort compared to medication alone. Continued support of research studies, such as the one performed at the University of Florida with Drs. Kleman and Estrada, will enable veterinary cardiologists to advance the care of dogs with SAS and learn how best to treat this unfortunate condition.

A very special young female Newfoundland, that started out with less than desirable health and circumstances, has an opportunity to live, thanks to Dr. Brian Scansen, DVM, MS, Dipl ACVIM (Cardiology) at The Ohio State University College of Veterinary Medicine (OSU CVM) and the Newfoundland Club of America Charitable Trust

After cleaning away the dirt and removing multiple ticks, a “Lucky Penny” landed with South Central Newfoundland Rescue (SCNR) as a new foster. She had cherry eye in both eyes affecting her vision so badly she literally ran into things. She was surrendered to SCNR from another rescue organization in hopes that a forever home, familiar with subaortic stenosis (SAS), would be found. She had already had a cardiac ultrasound by a veterinary cardiologist who reported severe SAS at roughly six months of age, which is not a good prognosis for a long future.

Since there is no way to know how long dogs with severe SAS will live, SCNR decided to take it one step at a time. First, Penny had received the suggested heart medication, Atenolol, from the cardiologist. Secondly, her cherry eyes were a serious problem. In order to get better answers to these concerns, a copy of her cardiac ultrasound report was forwarded to Dr. Scansen at Ohio State. The goal was to make her comfortable and let her live her life to the fullest, whatever that may be. Dr. Scansen advised to start the medication, and said that the eye surgery, while risky, should be manageable if done either at Ohio State with extra monitoring or by an experienced surgeon who could complete the surgery quickly. Surprisingly, he added that based on Penny’s ultrasound report and her age, he felt that she was a good candidate for a novel procedure to treat SAS—cutting balloon valvuloplasty. He stated that this procedure could reduce the severity of her SAS, which could lead to improved quality of life and survival. The concern was that the procedure itself carries a moderate risk, with no long term results yet available. However, preliminary results based on a recent study from the University of Florida were positive.

Since this was such a serious issue needing more input and investigation, SCNR forwarded Dr. Scansen’s comments to Mary L. Price for her input and discussion. Mary immediately recognized the cutting balloon valvuloplasty procedure as part of the 2009 research study at the University of Florida that had been partially funded by a grant provided by the Newfoundland Club of America Charitable Trust Newfoundland Health Challenge. After more research and a lot of heartfelt consideration, it was decided to ask the NCA Trust Rescue Fund to fund Penny’s surgery. What started as just keeping Penny comfortable for whatever time she had left had now become a chance for better/longer survival and a definite impact for Newfoundland health overall. In trusting Dr. Scansen, it was apparent that he would not do this surgery unless he felt he could truly help Penny. Her survival and well-being continued to be the primary focus. In gathering more information, Dr. Scansen reported: “Initial results from the group at University of Florida showed the severity of SAS in those dogs decreased from 160mmHg to about 90mmHg. (Penny’s was at ~165mmHg which would possibly worsen as she grew).”

The Newfoundland Club of America Charitable Trust Management Board (CTMB) discussed the case and a major part of the discussion was the realization that some dogs with severe SAS live near-normal lives without intervention, while others die young. Normal life expectancy for severe SAS, without any treatment, is 2-3 years. This surgical decision was not entered into lightly, and ultimately it came down to seeing if this procedure would help this puppy. The added benefit would be that what was learned from Penny could possibly help other Newfoundlands and breeds that suffer from this horrible disease. The Trust Board unanimously approved the procedure with the understanding that all information learned would be reported back to the NCACT throughout this puppy’s life.

In discussing Penny’s overall health going forward, it was decided to proceed with the cherry eye surgery before the heart procedure. It was obviously impairing her vision and needed to be addressed. Dr. Joe D’Amico, from Waynesville Veterinary Hospital in Waynesville, Ohio, agreed to do her eye surgery with a very light anesthesia. Fortunately, with the exception of being a naughty Newfie puppy who didn’t want to stay still during recovery, she recovered quickly and completely.

To prepare for the cutting balloon valvuloplasty, Dr. Scansen did another cardiac ultrasound to verify any changes and to take measurements to determine the size of the cutting balloon needed. The heart pressures were similar to the initial report; however, over the two months that had passed Penny’s heart had enlarged, which pointed to progression of her SAS.

In Dr. Scansen’s opinion, based on Penny’s measurements, Penny was a good candidate for the procedure, though two different approaches to enter the heart were being assessed. The Florida Study approached through the neck, basically straight down through the aortic valve. The other option was to come through the back leg which leaves easier ways to stop potential bleeding, but gives a longer path and a smaller artery to work with. Ultimately it was determined that going through the neck would be the best approach so larger balloons could be used if needed. A pediatric interventional cardiologist from Nationwide Children’s Hospital in Columbus, Ohio, Dr. John Cheatham, agreed to assist with the surgery and donated his time and the balloons necessary. Since similar procedures are commonly performed on humans, Dr. Cheatham could offer experienced insight if needed.

Through all the testing, and handling, Penny was a real trooper. She didn’t know how sick her heart was and had no idea how sick dogs were expected to act. She thoroughly enjoyed the OSU veterinary students and greeting visitors in the waiting area. At roughly eight months old, she was blowing puppy coat, so she not only left her good Newfie cheer with everyone she met, she also left the fluffy Newfie puppy coat throughout the building.

Early on a Monday morning, Penny was admitted to OSU for the cutting balloon procedure. (It was expected that we would hear in about five hours how things went or sooner if they didn’t go well.) A transesophageal echocardiogram was performed, along with other tests, at the beginning of sedation to confirm where the stricture was and that everything was okay to proceed. During this time, Penny was totally dependent on the veterinary cardiologists and anesthesiologists keeping her alive with their skilled experience and technology. The skill level of these individuals is impressive and Penny benefitted greatly, as abnormal heart rhythms (arrhythmias) were quickly brought under controlwith medications during surgery. Penny’s stricture was high near the valve area, which when ballooned could cause damage to the aortic valve itself resulting in leakage. An 8mm cutting balloon was used for Penny, followed by an 18mm Kevlar high pressure balloon, which appeared to tear the subaortic stricture.

The surgery was done by inserting a tiny wire into an artery in her neck, directing the wire across her aortic valve and into her beating heart guided by fluoroscopy (real-time X–rays), and by then placing the expandable cutting balloon over the wire. With the heart moving with every beat, the cutting portion was snaked into the heart and through the aortic valve to the stricture. Continuously monitored by video X-ray,2 the cutting balloon was expanded to expose the cutting blades a half a millimeter, which scores the stricture to weaken its band. Once scored, the larger high pressure (non-cutting) balloon was then inserted and expanded to break open the stricture more completely. (This is sort of like breaking a string tied around your finger that was decreasing the circulation but not stopping it.) The balloon expansions take 10-15 seconds, during which the blood circulating through the heart was literally stopped. Overall, Penny was under anesthesia for four hours.

Penny’s heart pressure immediately after the cutting balloon procedure was reduced by about two-thirds, which was very favorable. She recovered overnight in the Intensive Care Unit and her heart rhythm was continuously monitored. The cardiac ultrasound after surgery showed a little bit of mobile tissue, representing the torn stricture, as well as mild to moderate leakage from the aortic valve. The tissue left should be held open by the continuous blood flow through that area. With this information, Dr. Scansen was very pleased with how things looked, and that all went according to plan.

Historically, non-cutting and lower pressure balloons have been tried to open the stricture that develops with SAS. The largest study looking at the efficacy of non-cutting balloons for canine SAS was performed at The Ohio State University. They proved to stretch the opening provided initial relief, but did not have superior results in the long term.

When going over post surgery information, Dr. Scansen reemphasized Penny’s condition going into surgery. He said that her SAS appeared to be advancing quickly given the combination of her age, severity of her disease, the fact that the mitral valve was beginning to leak, and given her heart enlargement. Of course there were no guarantees either way, but he felt strongly that this was the right thing for her at this time for future longevity.

It was expected that she would be in the hospital at least two days, and if abnormal heart rhythms or other complications occurred, it might have to be a bit longer. However, she did so well that she was able to go home the day after surgery! We picked her up the very next day, sporting a nice bright red collar of Vet wrap, with three small stitches in her neck and shaved areas on all four legs as well as on her right side and her neck/chest. She was quite the sight, and the leash looped around her front legs was not holding her back, so she was quickly fitted with her very first Newfie Ruff Wear harness.

Overall, the OSU veterinary students fell in love with her, and she had a good time keeping them on their toes. She’s a sassy barker, and doesn’t like to be alone, so as soon as they walked away from her crate/cage, she let them know it. She was sent home with a few more days of antibiotic (Clavamox), was started on Enalapril, and continued on the Atenolol. The Enalapril relaxes the blood vessels and widens them for easier blood flow. The Atenolol is a beta blocker that decreases heart rate and lowers the work load of the heart, allowing the heart to require less oxygen to work properly. She will likely be on both of these heart medications the rest of her life.

Ten days post surgery the sutures were removed and her blood work checked for kidney and liver values, which were well in the normal range. Her blood pressure was checked, and it was within normal range for an SAS dog.

Five weeks post surgery; she had a follow up cardiac ultrasound with Dr. Scansen and everything looked great! He was very pleased that the left side of her heart had slightly decreased in size, making her overall heart size smaller. The pressure going through the aortic valve was still reduced—from 165 mmHg before surgery to 78 mmHg after surgery. Overall, Dr. Scansen said she looked great and he was thrilled with these results.

Penny has gained another five pounds, but is still on the thin side even though her food has been increased again. She’s a little high in the rear right now, so she’s growing and thriving like a normal Newfie puppy.

Eleven weeks post surgery, Penny acts like a normal Newfoundland puppy that thinks she’s a goat and can climb the highest mountain. She loves squeaky toys and has learned some basic house manners. We don’t know how this is going to end, but Penny has been given the opportunity to live and what we learn from her, we hope will help others just like her. Now we wait; the rest is up to her.

1. $10,000 for AKC/CHF Grant #1142, “Cutting Balloon Valvaplasty for Dogs with Subaortic Stenosis”, chief investigator Amara H. Estrada, DVM, DACVIM, University of Florida - $42,704. This study explored a balloon valvaplasty procedure for canines with SAS, using a balloon procedure that incorporates cutting blades to score/cut the fibrous ring inherent to SAS to prevent it from re-forming—to increase the lifespan of the dog.
2. http://www.ncanewfs.org/health/diseasearticles/balloonvalvoplasty.html

SubAortic Stenosis in Newfoundlands

by Jennifer Zablotny, DVM

Subaortic stenosis is a congenital, genetic heart defect. It can affect any breed of dog, but is most commonly seen in Newfoundlands, Golden Retrievers, and Rottweilers. It is typically diagnosed in puppies 16 weeks of age or older, although more severe cases will present with a murmur at younger ages.

SAS is a narrowing (stenosis) of the left ventricular outflow tract just past the aortic valve (subvalvular). In a normal dogheart, blood lacking oxygen flows from the body to the right atrium and into the right ventricle where it is pumped through
the pulmonary artery and into the lungs. After picking up oxygen from the lungs, the blood returns to the heart through the left atrium and then into the left ventricle where it is pumped out into the body via the aorta. Pumping blood into the lungs doesn’t require much effort, so the right ventricle has a thinner wall than the left ventricle. Pumping blood into the body, however, requires a lot of force, so the wall of the left ventricle is much thicker. Muscles get larger when they are used.

When a dog is affected by SAS, there is a fibrous band of tissue just past the aortic valve. This band can range from a mild narrowing of the outflow tract to a severely narrowed tract. The narrower the tract, the harder the left ventricle has to work to push blood into the aorta and the body. Think of putting your hand over the end of a garden hose and narrowing the opening. Since the left ventricular muscle is working harder, it gets thicker than it should be. This can cause two scenarios. In the first, the muscle is so thick that it doesn’t get enough oxygen and part of it dies. This causes scar tissue to form, and scar tissue doesn’t conduct electrical impulses as well as normal muscle. Abnormal electrical impulses cause arrhythmias in the ventricle, and death occurs suddenly. In the second scenario, the left ventricular wall is so thick that it is making the chamber smaller and not enough blood is able to flow from the left atrium into the left ventricle. This can overload the lungs and the right ventricle causing congestive heart failure. This is not typical of SAS, but it can occur.

A related disease is pulmonic stenosis (PS). This is a narrowing of the right ventricular outflow tract. Since the right ventricle isn’t very thick to begin with, it has a lot more room to enlarge before there are problems. PS is also genetic and affected individuals shouldn’t be bred, but they aren’t in as much danger from sudden death as individuals affected with SAS. Dogs with a loud PS murmur can live a normal life span.

Diagnosis of SAS is anything but straightforward. The narrowed artery produces turbulent flow, which causes a murmur best heard on the left side of the chest at the heart base. In general, the louder the murmur and the earlier that it is heard, the more severe the disease. Many breeders have their puppies screened for cardiac diseases by a veterinary cardiologist prior to leaving for their new homes at eight to 10 weeks of age. This helps breeders avoid placing puppies with potentially serious heart defects. The problem with this is that not all murmurs that are heard at eight weeks are pathologic, and puppies with a mild narrowing may not have a murmur when they are checked.

Any heart disease that causes turbulent or abnormal blood flow will create a murmur. Pulmonic stenosis and patent ductus (PDA) are two other congenital heart diseases that are also seen in Newfoundlands. A PDA murmur is very characteristic and wouldn’t be confused with a murmur caused by SAS. Innocent murmurs in puppies are usually gone by 16 weeks of age. These murmurs aren’t caused by any underlying disease process and are fairly common across breeds. Puppies without a SAS murmur at eight weeks may have one by 12 or 16 weeks. That doesn’t mean they didn’t have SAS at eight weeks, it just means that the narrowed outflow tract was big enough for the eight-week-old puppy and didn’t grow. The puppy did and now the opening is abnormally small for the larger dog. Waiting as long as possible to check puppies will help avoid this problem.

Adult Newfoundlands should be ausculted by a veterinary cardiologist after a year of age. They have reached most of their growth, so any stenotic areas should be causing a murmur. While auscultation is a very cost effective and accurate method to screen adult dogs for SAS, any dog, especially breeding animals or puppies over the age of 16 weeks, that has a murmur should have an echocardiogram or ultrasound of the heart. Innocent murmurs are not uncommon in large and giant breed, athletic dogs. Exercise alone is enough to cause a murmur in some individuals. This is not pathologic, and an echo will confirm a normal heart.

In dogs affected by SAS, an echo can grade the severity. Colorflow Doppler measures the velocity of the blood across the aortic valve. Severe narrowing causes increased speed. (Remember the garden hose.) Gray areas occur when a dog may or may not have a murmur, there is no visible sign of a band of tissue below the aortic valve, left ventricular wall thickness is normal, and velocities are at the upper end of normal. Does this dog have SAS or is it an athletic heart in a giant breed
dog? Unfortunately, there are no established normal ranges for
blood flow velocity specific to large or giant breed dogs. (OFA
Cardiac database statement)

Definitive and accurate diagnosis of SAS is only possible with a necropsy. There are some individuals that will not have a murmur, will have a normal echo, and the SAS lesion will be found at necropsy. The use of this diagnostic is undesirable in breeding stock and most pets, so for now, we are left with auscultation and echocardiogram for diagnosis of SAS in living dogs. It is wise to perform a necropsy in breeding animals that die suddenly, regardless of previous auscultation or echo results.

Treatment of SAS varies with the severity of the disease. Mildly affected dogs can have normal lifespans without treatment. Medical therapy can increase the lifespan of moderately affected dogs and also improve quality of life if they are suffering from congestive heart failure. Severely affected dogs will require surgical intervention and medical therapy. The NCA Charitable Trust has funded a study examining the efficacy of cutting balloon valvuloplasty. The narrowed band of tissue is expanded and cut at the same time with a balloon on a catheter. This appears to be a promising technique as the narrowed section of artery is enlarged reducing the stress on the left ventricle and the cuts don’t allow it to narrow again. Prevention of this disease is the better course of action. Unfortunately, the genetics of the condition are muddled at best.

There are several genes involved in SAS with different modes of inheritance. Screening puppies prior to placement prevents unsuspecting owners from acquiring a heartache dog, and breeders can avoid investing time and money in a promising puppy. What to do with puppies that have murmurs is controversial. Some breeders euthanize all puppies with murmurs. That may be fine if the puppy has SAS, but these breeders may be euthanizing normal puppies with innocent murmurs or puppies with less serious pulmonic stenosis unless they are echoing all puppies with murmurs.

A veterinary cardiologist should listen to all Newfoundlands a year of age or older, regardless of the their breeding status. Cardiac clinics are commonplace in many areas at dog showsand there is always a cardiology clinic at the National. Results should be reported back to the breeder, at the very least. There is considerable controversy over whether all breeding animals should have an echocardiogram performed. Many cardiologists feel that auscultation is sufficient and detects the majority of SAS affected individuals. Echo is a more sensitive test, but it is also more expensive and may not detect enough affected individuals to make it cost effective for the population. If a dog is producing a high percentage of SAS puppies, it may be beneficial to echo that dog and make sure that individual is not affected.

Phenotypic testing obviously has its limits. Testing for the gene that actually causes SAS would be ideal. Dr. Linda Meurs at the North Caroline State University Cardiology lab is working on that. With funding from the NCA Charitable Trust, she is recruiting samples of normal and affected Newfoundlands. The dogs must have had an echo to confirm SAS or normal and copies of that report along with a three generation pedigree need to be sent with two to three cc’s of blood in a lavender top tube. For more information, please visit: http://www.cvm. ncsu.edu/vhc/csds/vcgl/newfoundlandcardiacresearch.html SAS can be a frustrating and heartbreaking disease to deal with. Educating breeders and potential puppy purchasers has raised awareness of this disease and the steps needed to reduce the incidence in Newfoundlands. Ultimately, identification of the abnormal gene will make it possible to eliminate SAS from our dogs.

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