Diseases of the Heart – Chapter 1: The Cardiac “Rhythm Section”

The term "heart disease" refers to any abnormality of the heart

On my way home from high school one afternoon, one of my classmates asked me if I would like to adopt a kitten. Right away I called my mom and got her permission. “Sphinx” was adorable and I was so happy to be able to give him a home and take care of him.

During Sphinx’s first veterinary visit I was immediately told by the veterinarian that he had “something wrong with his heart.” While the veterinarian was still listening with his stethoscope, I started thinking about Sphinx and how he’s probably going to suffer and die very young. Even before the veterinarian finished his exam, I had already imagined about a dozen scenarios, all of which were sad and some tragic. At the end of the exam I was informed that Sphinx only had a mild murmur which would most likely not cause any complications. Although that was welcome news, I was still very concerned since “heart disease” sounds serious no matter what kind it is. I was glad to find out year after year during his annual exams that although he still had a mild murmur, it still was nothing to be worried about. Sphinx lived to become 15 and he remained active and happy for most of those years.

“Heart Disease” includes any abnormality of the heart. This is a very broad diagnosis which can include many different categories, some serious and some less serious or more manageable. During the next few weeks I will try to cover many different diseases of the heart and their treatments. This week I will briefly summarize murmurs and disturbances in cardiac rhythm. Next week I will discuss Heart Failure in more detail.

  • Heart Murmurs- These are generally caused by a turbulent blood flow and are usually categorized from Grade I all the way to Grade VI. Grade I is the lowest intensity murmur which is typically detected only if the room is quiet and Grade VI is an extremely loud murmur that can be heard even as the stethoscope is being removed from the chest.
  • Abnormal Rhythms- Arrhythmias are abnormalities of cardiac rate and regularity. There are several different classifications such as “Sinus bradycardia” which is a slow heart rate; “Respiratory sinus arrhythmia” which is a condition when the rate increases with taking in a breath and decreases when the breath is exhaled. “AV block” is when the cardiac impulse to beat is delayed. If this block becomes a full block then a pacemaker may be required. “SA block” is when the heart fails to generate impulses. In many of these cases treatment may include a drug called theophylline or one called atropine. If still unresponsive to treatment then a pacemaker may be required.
  • Atrial fibrillation- This is characterized by a rapid and irregular cardiac rhythm. In dogs and cats, atrial fibrillation with fast heart rates usually is an indication of severe cardiovascular disease. The goal of treatment is to slow the heart rate down with medications such as digoxin, amlodipine, and atenolol.

It is important to remember that not all cardiac diseases are immediately life-threatening. Some can be managed by simply giving a daily dose of the required medication. Others may not need any medication at all but may require that you limit certain types of activities or foods.  Getting regular veterinary examinations is the best way to find out what condition your pet has and the best treatment options. Additionally if you have any questions relating to the medications that your pet is taking, you may call your 1800PetMeds pharmacist who will be happy to help answer any questions that you may have.

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  1. I had a question about lymphoma in the chest cavity. My dog has Erlichiosis from a tick bite. He has now developed enlarged lymph nodes in his chest cavity due to the Erlichiosis. I should add he is part Sheperd. He is on prednisone and doxycycline. If these medications remove the Erlichiosis will the lymphoma threat also be removed or is he stuck with that for the rest of his life?

  2. Dr. Michael Dym, VMD veterinarianJuly 31, 2013 at 1:22 pm

    I would make sure your pet has been diagnosed accurately for lymphoma with lymph node aspirate or biopsy. If lymphoma is confirmed, then treatment options include chemotherapy, or working with a holistic/homeopathic veterinarian on more natural long term treatment options.

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