A heart murmur is an auditory phenomenon, an extra or unusual sound heard during the heartbeat, rather than a direct physical sensation a person experiences. This sound is simply the noise of blood moving through the heart in a turbulent fashion. The symptoms people associate with a murmur are not the sound itself, but the physical effects of the underlying condition that causes the sound.
The Nature of a Heart Murmur
A heart murmur represents a deviation from the typical “lub-dub” sounds that a healthy heart makes. The normal sounds are produced by the rhythmic opening and closing of the heart’s four valves as blood is pumped through the chambers. A murmur, by contrast, is a whooshing, swishing, or rasping noise that interrupts this regular pattern.
This distinctive sound is created by turbulent blood flow, where the blood moves chaotically. The physics of this process is similar to water rushing through a narrowed hose, where increased velocity and obstruction cause vibrations and noise. These resulting vibrations in the heart chambers or blood vessels are what a medical professional detects with a stethoscope. Since these vibrations are sound waves, the patient does not feel the murmur, but rather the effects of the condition generating it.
Classifying Heart Murmurs
Heart murmurs fall into two broad categories defined by their cause and clinical significance. The first type is the “innocent” or functional murmur, which occurs when blood flow is temporarily faster than normal but no structural heart defect exists. These harmless murmurs are common in children, often disappearing by adulthood, and can also appear during periods of high blood flow, such as during exercise, fever, or pregnancy. Innocent murmurs are generally asymptomatic and do not require medical treatment.
The second category is the “abnormal” or pathological murmur, which signals an underlying structural problem within the heart or major blood vessels. In adults, these murmurs are typically caused by heart valve disease, such as a valve becoming stiff and narrowed (stenosis) or failing to close completely and allowing blood to leak backward (regurgitation). When a valve is defective, it forces the heart to work harder to maintain circulation, leading to the physical symptoms that patients notice. These murmurs can be associated with conditions present since birth or acquired later in life.
Physical Sensations Associated with Abnormal Murmurs
The symptoms experienced by a person with an abnormal heart murmur are directly linked to the heart’s reduced efficiency in pumping blood. One of the most common sensations is persistent fatigue or generalized weakness, which results from the body’s tissues not receiving an adequate supply of oxygenated blood. This decreased tolerance for physical activity is often one of the first signs that the heart is struggling to keep up with metabolic demands.
Patients frequently report shortness of breath, medically known as dyspnea, which can occur during even minimal exertion or sometimes while at rest. This sensation may also manifest when lying flat, as the position allows fluid to redistribute and increase pressure on the lungs. The heart’s inability to effectively move blood forward can lead to a backup of fluid in the lungs, creating this noticeable respiratory distress.
Another set of sensations involves the heart’s rhythm, presenting as palpitations, which is a feeling of the heart fluttering, racing, or skipping beats. This irregular or rapid heartbeat, called tachycardia, is the heart’s attempt to compensate for the reduced volume of blood being pumped with each contraction. Chest discomfort or pain, sometimes described as pressure or tightness, can also be a symptom, though it can have various causes.
Fluid retention is a manifestation of impaired heart function, leading to noticeable swelling, or edema, in the feet, ankles, and legs, and sometimes extending to the abdomen. A person may also experience episodes of dizziness, light-headedness, or sudden fainting spells, known as syncope. These sensations occur when the brain receives insufficient blood flow, particularly when changing position or during intense activity.
How Doctors Identify Murmurs
Since a patient cannot feel the actual sound of a murmur, medical professionals rely on specific diagnostic techniques to detect and evaluate it. The first step involves auscultation, which is the process of listening to the heart with a stethoscope. A trained ear can distinguish the unique pitch, timing, and location of the whooshing sound to gain initial clues about its potential cause.
Doctors also use a grading system to describe a murmur’s loudness, ranging from Grade I (barely audible) to Grade VI (loud enough to be heard even with the stethoscope slightly off the chest). The timing of the sound within the cardiac cycle—whether it is systolic (during contraction) or diastolic (during filling)—helps pinpoint the affected valve or structural issue. If a murmur is abnormal, the next step is typically to perform an echocardiogram. This non-invasive ultrasound uses sound waves to create moving images of the heart’s valves and chambers, providing a detailed view of the blood flow and the structural cause of the turbulence.