Dharma was referred to Dr Margiocco because her family veterinarian had detected an abnormal heart rhythm (cardiac arrhythmia) approximately two weeks earlier while investigating Dharma’s history of exercise intolerance and an episode of acute weakness (“flopping down”) while walking. Dharma was not receiving any medication at that time.
An ECG was done and revealed a heart block (second degree AV block) causing an abnormally low heart rate which was likely responsible for her episodes of weakness. The red arrows show where the blocks occur.
The next step was to give atropine, a medication used to increase the heart rate. As her heart rate did not respond as expected (it should have increased significantly), structural damage to the heart’s conduction system was suspected. An ultrasound (echocardiogram) was normal indicating the absence of other significant heart diseases.
A 24 hour Holter monitor (continuous ECG reading) recording was able to detect that Dharma’s heart rate frequently dropped down to approximately 40 beats per minute during the day, which is a quite low heart rate for a dog.
Advanced second degree AV block carries a high risk for the patient. An artificial permanent pacemaker is the treatment of choice for this condition.
Dharma was hospitalized the day prior to the pacemaker implantation surgery. On the day of the procedure, we placed two adhesive electrodes on her chest to be able to pace her heart once she was anesthetized (in case her heart rate dropped dramatically during the procedure).
Dharma’s surgery went very well and the anesthesiologist was happy with how quickly she recovered from anesthesia in the intensive care unit.
She was discharged to the care of her owners the day after the procedure.
Her ECG at discharge showed that the pacemaker was indeed taking over when her heart block (red arrow) would have caused a drop in the heart rate. The pacemaker (blue arrows) takes over and ensures that her heart rate is maintained in a normal range to allow her to go about her Lhasa Apso dog activities.
Sutures were removed 9 days later, and a brief recheck two weeks after the surgery showed that Dharma was healing without complications. We can barely see the small neck incision.
Dharma was scheduled to come back at the beginning of this year. At that time the pacemaker will be “interrogated” with a special computer via a radiofrequency “wand” placed on the patient’s skin. Modern pacemakers collect and store data that is used to optimize the settings of the device with the intention of optimizing the patient’s quality of life and of maximizing the battery duration.