Coco is a charming three-year old Cavalier King Charles Spaniel and her pet parents anticipate years of companionship with her after seeking an “implantable solution” to her life-threatening condition at Hope Veterinary Specialists.
Earlier this year, Coco was at her primary veterinarian being examined for an issue with her paw. Coco suddenly had a fainting spell and it was determined that she had a very slow heart rate during that episode. She responded well to an IV medication to temporarily increase her heart rate and was started on an oral medication to be given twice a day every day at home to try to prevent further drops in her heart rate and subsequent collapse episodes.
Through her primary veterinarian, several electrocardiograms (ECGs) as well as an echocardiogram (ultrasound of the heart) were done to monitor her condition. While no structural heart disease was found to explain her collapse, an additional diagnostic tool was used in March 2015 to determine what her heart rate was doing when she was at home. A Holter Monitor is a portable ECG device that records cardiac activity continuously over a 24-hour period. Pet parents are instructed to record any notes about the pet’s activity level or abnormal behavior while wearing the monitor. The great thing about the Holter Monitor is that it can detect things that may not be apparent during an in-clinic evaluation and it can also detect and record events that may happen when the owner is not at home or sleeping. The Holter Monitor recording revealed new information: Coco had a 20-minute period where she was experiencing third-degree atrioventricular (AV) block. This meant that the electrical impulses from the upper chambers of her heart (atria) were not reaching the lower chambers of her heart (ventricles) and subsequently the heart was not beating at an appropriate rate to meet her body’s needs. At one point, her heart rate was as low as 32 bpm (normal range for dogs is generally from 80 to 140 bpm).
Coco was evaluated by a cardiologist in May 2015 and she was still experiencing collapsing episodes. The ECG done at that time revealed Coco’s heart rate was 70 bpm and that she had a high grade second-degree AV heart block. While this meant that some of the electrical impulses were now reaching the ventricles, there was a concern that medication would not be able to control Coco’s heart rate and clinical signs long-term.
It was at this time that Coco was referred to the Cardiology Service at HOPE Veterinary Specialists. Dr. Ellen Davison reviewed Coco’s history and evaluated her suitability to receive a permanent transvenous pacemaker- an “implantable solution” that would generate the electrical impulses her heart needed to pump reliably. During this first evaluation at HOPE, Coco’s ECG confirmed the second-degree AV block. Given Coco’s history of fainting/collapse and her Holter recording and subsequent ECG findings, a permanent pacemaker was recommended and Coco’s pet parents agreed to this procedure. Since the pacemaker would ensure her heart rate did not get too low or experience any pauses, she would no longer collapse or faint after it was placed.
Pacemakers have been available for a number of years for use in dogs. It is estimated upwards of 500 dogs receive pacemakers annually. Coco’s pacemaker was acquired from a non-profit organization that obtains donated, unused human pacemakers with sufficient battery life directly from the pacemaker manufacturers.
Coco was taken to surgery on June 10, 2015 to have her permanent pacemaker placed. Our cardiologists, Drs. Ellen Davison and Dennis Burkett, worked together to perform the procedure. Once Coco was prepped and under anesthesia, a small incision was made on the right side of her neck. The pacemaker lead was advanced under fluoroscopic guidance to her right ventricle, where it was secured. After creating a second small incision, the pulse generator (consisting of an enclosed micro-computer and battery) was implanted beneath the skin on her neck. The pacemaker was programmed with the appropriate settings prior to the procedure which meant that it started working as soon as it was placed. A post-operative radiograph documented the placement of the pacemaker. Coco recovered from anesthesia uneventfully and was discharged the following day with a heart rate of 100 bpm! At subsequent rechecks, her pacemaker settings have been fine-tuned to meet her body’s requirements based on her activity level as well as to optimize battery life. She is once again a bright and alert pup and the long-term outlook for her health and activity level is good. Coco has resumed a normal, happy lifestyle and no longer requires daily medication to try to control her heart rate.