Now that we’ve covered the various types of valvular heart disease, let’s look at it from a different perspective and discuss heart murmurs. Most patients think that a heart murmur and a valve problem are identical, but there are important differences. Understanding this will help you make sense of why you don’t always need to be concerned about a heart murmur.
A heart murmur is a sound that is made during the cardiac cycle. When the ventricles contract (pump), they force the mitral and tricuspid valves to close—this creates what we call the first heart sound (abbreviated “S1”). The second heart sound (“S2”) occurs when the ventricles start to relax, leading to closure of the aortic and pulmonic valves. In popular phrasing, we refer to the sounds of S1 and S2 as “lub-dub.”
Heart murmurs are extra sounds that occur in between the two heart sounds and usually have a blowing or whooshing quality when listened to with a stethoscope. Murmurs occur because there is some turbulence in the blood flow. Think of a river: if the flow is steady and the water isn’t bouncing off rocks or the sides, you don’t hear it. Only when there is turbulence does the river make noise. Similarly, we can’t normally hear the blood flowing from one chamber to the next across a heart valve. But if a valve doesn’t open well (stenosis), the normal volume of blood trying to get across that valve moves more turbulently, leading to a heart murmur. And, if a valve doesn’t close all the way and blood regurgitates backward, that blood is also going through a smaller opening (the small residual opening of the incompletely closed valve), which again creates turbulence. Murmurs can also occur due to holes in the heart—between two chambers—as the blood passing through this opening becomes turbulent.
So why aren’t murmurs always bad? If the heart is pumping more blood across the valves—even if they aren’t narrowed—the extra blood flow can lead to turbulence and thus a heart murmur. Situations where extra blood is being pumped include exercise, pregnancy, if a person is anemic, if a person has a fever, or if the thyroid is overactive, just to name the most common reasons. Furthermore, heart murmurs can be noted in adolescence, when the body is growing rapidly.
Another thing to keep in mind is that the loudness of a murmur doesn’t necessarily correspond to how serious the problem is. People can have a valve that regurgitates or is stenotic—but is not severe and may never become severe—but have a clearly discernible heart murmur.
Finally, it’s important to keep in mind that murmurs can mean different things at different points in a person’s life. Many people have been told that they had a heart murmur when they were a child or a teenager. When they are noted later in life to have a heart murmur, they may assume “I’ve always had that.” But for the vast majority of people with heart murmurs in childhood or adolescence, the heart murmur goes away once a person is an adult. A heart murmur later in life thus represents something completely different, perhaps a valve that doesn’t open or close properly.
So, what should a person do who is told he or she has a heart murmur? Generally, get an echocardiogram—that is the best test to look at the valves and also make sure there is no “hole” in the heart. Once you’ve had that, ask your doctor what is causing the heart murmur. If it is a valve problem, is it mild or severe? How likely is it to become severe? These are all questions that a cardiologist should be able to answer for you. And, while not all heart murmurs represent a serious problem, it’s important for you to know whether your heart murmur does or doesn’t. Take the initiative to ask questions and find out.
Greg Koshkarian, MD, FACC