Heart Murmurs
A heart murmur is an extra heart vibration that results in an abnormal sound caused when there is a disturbance in the blood flow. The detectable noise is one that is distinguishable from a regular heartbeat and can be heard by a doctor with the use of a stethoscope. Heart murmurs can be broken down into three types: systolic, diastolic, and continuous. They are graded on a scale of 1 to 6, with 1 being the softest and hardest to hear, and 6 being the loudest. Veterinarians go by the number scale to determine the cause of the murmur and the best course of action to take, if necessary.
If your cat has a murmur, it is not an immediate cause for panic. Talk with your vet about heart disease and what it might mean for your cat should there be something more serious going on. Many cats diagnosed with heart murmurs never need any treatment and go on to live long and healthy lives.
Heart Murmur Symptoms:
Irregular heartbeat
Hacking, persistent cough
Excessive panting even when resting
Tires easily
Lack of energy
Collapses or faints
Gums and/or tongue are bluish in color
Racing pulse
Lack of appetite
Severe water retention
Grades of Heart Murmurs
Grade 1 – These are the least serious. They are extremely soft in sound and barely audible.
Grade 2 – A soft sound heard through the use of a stethoscope.
Grade 3 – Intermediate loudness and radiates to more than one location.
Grade 4 – These murmurs are moderate to intense and can be heard on each side of the chest.
Grade 5 – Very loud and can be heard even when the stethoscope is barely touching the chest. They can also be felt by holding a hand against the chest.
Grade 6 – Like a grade 5, these murmurs are very loud and can be felt by touching the chest; they are also the most severe.
Types Of Heart Murmurs
Systolic murmur: Most heart murmurs are systolic and occur during systole, the phase of the heart cycle when the heart contracts to pump blood out. The most common cause of this murmur is a leaky mitral valve (the valve between the left upper and lower chambers of the heart). Pulmonic stenosis or subaortic stenosis, which is a narrowing of the blood vessel that obstructs the blood flow, are less common causes of systolic murmurs.
Diastolic murmur: This type of murmur is uncommon in dogs. The most common condition associated with this type of murmur is aortic insufficiency, which occurs when the aortic valve leaks as a result of the fact that it does not close tightly.
Continuous murmur: This type of murmur is most often caused by patent ductus arteriosus (PDA), which is a failure of a large blood vessel, the ductus arteriosus, to close just after birth. It is the most frequent congenital defect in dogs and cats.
"Innocent" heart murmurs
Typically outgrown by 5-12 months of age
Innocent heart murmurs are sounds made by blood circulating through the heart’s chambers and valves, or through blood vessels near the heart. Innocent murmurs are common in children and are harmless. These heart murmurs may also be referred to as “functional” or “physiologic” murmurs.
A high percentage of human children, dogs and cats are likely to have had an innocent heart murmur at some time. Innocent murmurs may disappear and then reappear. When a heart rate changes, such as during excitement or fear, these innocent murmurs may become louder or softer. This still doesn’t signal that the innocent murmur is cause for concern.
Unless testing suggests that further inquiry is warranted, no next steps may be necessary. With an innocent heart murmur, your child won’t need medication, and doesn't have a heart problem or heart disease. You don't need to pamper or restrict diet or activities. Most innocent murmurs disappear at adulthood, but some adults still have them.
Articles
https://www.heart.org/en/health-topics/heart-murmurs
https://www.heart.org/en/health-topics/heart-valve-problems-and-disease/heart-valve-problems-and-causes/innocent-heart-murmur