A heart murmur refers to an unusual sound detected during a heartbeat. While the presence of a murmur might raise concern, many are harmless and do not indicate underlying heart disease.
Beyond the “Lub-Dub”
A healthy heart typically produces two distinct sounds, often described as “lub-dub.” The “lub” (S1) occurs when the mitral and tricuspid valves close at the beginning of the heart’s contraction phase, known as systole. The “dub” (S2) follows, resulting from the closure of the aortic and pulmonic valves as the heart relaxes and fills with blood, a phase called diastole. These sounds represent the orderly opening and closing of the heart’s valves, ensuring blood flows in one direction.
A heart murmur introduces an additional sound. It is commonly described as a “whoosh,” “swish,” or “blowing” noise. This extra sound is generated by turbulent blood flow within the heart or its major blood vessels. The murmur might be heard between the “lub” and the “dub,” or it could occur after the “dub,” depending on the specific cause and timing of the turbulent flow.
Understanding a Murmur’s Characteristics
When evaluating a heart murmur, healthcare professionals assess several characteristics to understand its nature.
Intensity
Intensity refers to the murmur’s loudness. Murmurs are graded on a scale from 1 to 6, where a Grade 1 murmur is very faint and barely audible, while a Grade 6 murmur is exceptionally loud, sometimes even audible without a stethoscope touching the chest. The loudness of a murmur does not always correlate with the severity of any underlying condition.
Pitch
Pitch describes whether the murmur sounds high-pitched, medium-pitched, or low-pitched. High-pitched sounds are often best heard with the diaphragm of a stethoscope, while low-pitched sounds are more discernible with the bell.
Timing
The timing of a murmur indicates when it occurs within the cardiac cycle in relation to the “lub-dub” sounds. Systolic murmurs happen during the heart’s contraction (between S1 and S2), diastolic murmurs occur during relaxation (between S2 and the next S1), and continuous murmurs are present throughout both phases.
Location
The location where the murmur is heard loudest on the chest provides clues about its origin, as different heart valves and areas of blood flow are associated with specific chest regions. For instance, murmurs originating from the aortic valve are often best heard at the second intercostal space at the right sternal border.
Quality
The quality of a murmur describes its unique sound, which can be characterized as harsh, musical, rumbling, or blowing. These specific characteristics help differentiate various types of murmurs and can guide further diagnostic evaluations.
Common Origins of Heart Murmurs
Heart murmurs arise from turbulent blood flow, which can occur for various reasons.
Innocent (Physiological) Murmurs
Some murmurs are categorized as innocent (physiological) murmurs, meaning they are harmless and do not indicate a heart problem. These murmurs are common, especially in children, and may be caused by normal, rapid blood flow through the heart. Factors such as fever, physical activity, pregnancy, anemia (low red blood cell count), or rapid growth spurts can temporarily increase blood flow and lead to an innocent murmur.
Abnormal (Pathological) Murmurs
Abnormal (pathological) murmurs signal an underlying heart condition that affects blood flow. These conditions often involve structural issues within the heart, such as narrowed or leaky heart valves. For example, a valve that does not open fully (stenosis) or one that allows blood to leak backward (regurgitation) can create turbulent flow and a murmur. Holes in the heart, like septal defects, or other congenital heart defects can also cause pathological murmurs.
When to Seek Medical Advice
If a heart murmur is detected, consult a doctor for a thorough evaluation. Only a medical professional can accurately assess the murmur, determine its specific characteristics, and ascertain whether it is an innocent murmur or a sign of an underlying condition. This evaluation typically involves listening to the heart with a stethoscope and may include further diagnostic tests if needed.
It is important to avoid self-diagnosis based solely on the sound of a murmur or perceived symptoms. While many murmurs are benign and require no treatment, some may indicate a more serious issue that benefits from medical attention. A healthcare provider can determine the appropriate course of action, which might range from no intervention to further investigation or treatment for any identified cardiac problem.