A heart murmur is not the same as a hole in the heart, although a structural defect can directly cause a murmur. A heart murmur is an audible swishing or whooshing sound heard during the heartbeat, distinct from the normal “lub-dub” sounds of the valves closing. This sound is a physical finding detected by a doctor using a stethoscope, indicating turbulent blood flow within the heart. While a structural problem, such as a hole, creates this turbulence, a murmur is fundamentally an acoustic phenomenon, not a diagnosis of a structural defect itself.
Decoding the Heart Murmur
A heart murmur is the sound generated by blood moving in a rapid, chaotic way through the heart’s chambers or valves. Normally, blood flows smoothly and silently, but turbulent flow creates vibrations heard as a whooshing sound. A physician uses the intensity and timing of this sound to help determine its origin.
Murmurs fall into two broad categories. The first is the “innocent” or “functional” murmur, which is not associated with any structural heart defect and is harmless. These sounds are often temporary, resulting from blood flowing faster than usual, such as during fever, intense exercise, or pregnancy, when the heart’s output is increased.
The second category is the “abnormal” or “pathological” murmur, which signals an underlying structural issue within the heart or its vessels. These problems force the blood to flow abnormally, creating the turbulent sound. Most murmurs discovered in children are innocent and typically do not require specific medical intervention.
Structural Causes The Hole in the Heart
The concern about a “hole in the heart” refers to a septal defect. The heart’s four chambers are normally divided by walls called septa, and a defect is an opening in one of these walls. These holes cause blood to flow from the high-pressure side to the lower-pressure side, a process called shunting.
Two common forms are the Ventricular Septal Defect (VSD) and the Atrial Septal Defect (ASD). A VSD is an opening in the wall separating the two lower pumping chambers (ventricles) and is one of the most common congenital heart defects. Blood shunting from the left ventricle to the right ventricle creates a high-velocity jet that generates a distinct, loud murmur.
The force of blood pushed through a small VSD opening causes significant turbulence, which is why a smaller hole can produce a louder murmur than a larger one. An ASD is a hole between the two upper chambers (atria). While it also causes shunting, the pressure difference is less dramatic, resulting in a different murmur characteristic. A septal defect is a structural problem, and the murmur is the acoustic evidence of the resulting chaotic blood flow.
Other Abnormal Causes of Murmurs
Pathological murmurs are frequently caused by problems with the heart’s four valves, not just septal defects. These valves ensure blood flows in only one direction, but damage or disease can compromise their function.
A valve that has narrowed or stiffened is called stenotic, which restricts the forward flow of blood. This forces blood through a tight opening, creating a murmur. Conversely, a valve that does not close completely allows blood to leak backward into the previous chamber, a condition known as regurgitation. This backflow also creates a specific turbulent sound heard as a murmur.
Stenosis and regurgitation can affect any of the four valves—mitral, tricuspid, aortic, or pulmonary—each producing a murmur with unique timing and location.
Another structural issue is a persistent ductus arteriosus (PDA), a blood vessel that remains open after birth, connecting the aorta and the pulmonary artery. This abnormal connection causes blood to flow continuously from the high-pressure aorta to the lower-pressure pulmonary artery, creating a distinctive, continuous “machinery-like” murmur.
Detection and Next Steps
The first step in evaluating any heart murmur is the physical examination. A doctor uses a stethoscope to assess the sound’s pitch, loudness, timing in the cardiac cycle, and location. These characteristics provide the initial clues necessary to distinguish an innocent murmur from one caused by a structural defect. If the murmur is innocent, no further testing or treatment is typically required, and it may simply be monitored.
If the murmur suggests a pathological cause, or if the patient has related symptoms like shortness of breath or dizziness, further diagnostic steps are necessary. The primary tool for investigating the heart’s structure and function is the Echocardiogram. This non-invasive test uses sound waves to create moving images of the heart, visualizing the valves, chamber size, and blood flow. It definitively confirms the presence and severity of a septal defect or valve issue.
Additional tests, such as an Electrocardiogram (ECG) to check electrical activity or a chest X-ray to look for heart enlargement, may also be used. Management for a confirmed structural defect ranges from careful monitoring for small VSDs that may close spontaneously, to medical therapy for symptoms, or surgical interventions to repair the hole or fix a damaged valve.