Different types of heart murmurs—and what yours is telling you

If you've ever listened to your heartbeat, you know it's a noisy organ. With its famous "lub dub, lub dub" sound, it makes quite the racket inside your body as it works to send blood throughout your body. 

"In most hearts, the beating is fairly rhythmic. But if you have a heart murmur, you have an additional sound when your heart beats, like a whooshing, rasping or blowing sound," says Tarun Mathur, MD, FACC, a cardiologist at Bryn Mawr Hospital, part of Main Line Health. "While often harmless, heart murmurs can also mean there's a problem occurring in your heart."

There are different kinds of heart murmurs, as well as a range of causes. Here's an overview of heart murmurs, including the types and what yours might be saying about your heart's health.

What is a heart murmur?

Your heart is like a large building with rooms and hallways. These rooms (or chambers) and hallways (or valves) work together to efficiently pump blood throughout your body.

There are four chambers—two atria (upper chambers) and two ventricles (lower chambers). As for the valves, they are situated between the chambers. They close every time your heart beats, making your blood flow in only one direction.

"Heart murmurs can happen for a few reasons, including a valve not closing tightly enough, (causing blood to leak in the wrong direction) or blood moving through a stiff or narrowed valve (called stenosis). Sometimes, this abnormal blood flow can indicate a problem in your heart," says Dr. Mathur.

The heart murmur sound meter

Heart murmurs are classified or "graded." The first categorization of heart murmurs is based on how loud they are. Your healthcare provider can determine this by listening to your heart with a stethoscope.

Grading is on a scale of 1 to 6, where 1 is barely able to be heard. A grade 6 heart murmur is very loud, and it doesn't require the stethoscope to come into contact with your chest to be heard.

"Some murmurs can also be felt with the palm of your hand over the heart, called a "thrill." This means your murmur is at least a grade 4," says Dr. Mathur.

Heart murmurs are also classified by when the abnormal sound occurs. They're either systolic (when the ventricles are pushing blood out) or diastolic (when the ventricles are filling back up with blood).

Innocent and non-innocent heart murmurs

Heart murmurs can be innocent or non-innocent, depending on their cause.

Innocent heart murmurs are harmless. They don't cause symptoms or health problems, and they don't need treatment. These murmurs are often caused by rapid blood flow to the heart from things like exercise or pregnancy. They can also be caused by anemia or hyperthyroidism.

"Innocent heart murmurs are also common in children and are a normal part of the heart's development. In fact, most children have one at some point. In most cases, they disappear by adulthood, but sometimes they remain for life," says Dr. Mathur.

Non-innocent heart murmurs—also known as abnormal heart murmurs—can indicate a problem in the heart, such as:

• Heart valve disease
• Hypertrophic cardiomyopathy, which is when the heart muscle is too thick, making it more difficult for blood to leave or fill the heart
• Mitral regurgitation, which is when the valve between the left heart chambers doesn't completely close, causing blood to leak backwards across the valve
• Aortic stenosis, which is a narrowing of the valve that leads to the aorta (large blood vessel branching off the heart) that reduces blood flow to the body, causing the heart to work harder

If you have multiple murmurs, that may mean there is more than one problem in your heart's function.

Ways to treat a heart murmur

Heart murmurs are often diagnosed at routine health check-ups. You may also have symptoms, such as shortness of breath, dizziness, chronic cough, enlarged neck veins or bluish-colored skin, that can indicate a heart murmur.

To diagnose a heart murmur, including if you have one and what kind, your healthcare provider will use a stethoscope to listen to your heart. They'll ask about your symptoms and review your personal and family health history. You may also need additional testing, such as an electrocardiogram (EKG), chest X-ray or echocardiogram.

"Innocent heart murmurs don't need treatment, and they don't come with any limitations to activity or lifestyle," says Dr. Mathur.

Treatment for non-innocent heart murmurs centers on treating the root cause of the murmur. In many cases, this involves medicine. In more serious cases, it may require surgery.

Being diagnosed with a heart murmur might feel scary at first. However, they are often harmless. What's more, they can be an important sign of how well your heart is functioning. Whether you need routine monitoring or further treatment, knowing you have a heart murmur helps support your heart's health for many years to come.

Next steps:

Make an appointment with Tarun Mathur, MD, FACC
Learn about heart and vascular care at Main Line Health
Should I worry if my heart skips a beat?