Heart murmurs are unexpected and unusual sounds that can be heard in the heart through a stethoscope. These heart murmurs are mostly harmless, but sometimes they can serve as indications of problems related to a damaged heart or overworked heart valve.
When a physician or primary health caregiver listens to the heartbeat through a stethoscope, the medical attendant listens to the heart at various places on a patient’s chest to hear the sounds the heart valves make as blood travels through the heart.
A healthy heartbeat typically has two sounds- a “lub-dub” sound. The initial sound, “the lub,” is heard as the mitral and tricuspid valves close.
The second heartbeat (sound) is the aortic and pulmonic valves snapping shut. A heart murmur is like a swishing sound that a doctor hears when there is turbulent or abnormal blood flow across the heart valve, and it can present itself at birth (congenital), during pregnancy for women, or later in life.
This heart sounds frequently originate from the abnormal movement of blood through the valves and between cardiac chambers.
When this happens, it results in turbulence which produces vibrations in the sections of the heart and outflow vessels (aorta and pulmonary artery) that are diagnosed as audible, low-frequency sounds.
Heart murmurs are distinct from the normal heart sounds representing semilunar and atrioventricular valves’ closure during a cardiac cycle.
Heart murmurs can be divided into two based on origin: first are those murmurs caused by valve defects, and secondly, those caused by antechamber defects.
Just like a heartbeat, murmurs can be separated into systolic and diastolic murmurs. A systolic murmur occurs during ventricular contraction (systole), and the diastolic murmur is heard during a ventricular filling (diastole).
To effectively understand heart murmurs’ pathophysiology, it is necessary first to understand the heart’s anatomy, the hemodynamic of blood flow (the physical factors governing the flow of blood), and the cardiac cycle (sequence of events that occurs as the heart contracts and relaxes).
Epidemiology of Heart murmurs
Heart murmurs are very common in children. These murmurs are the most frequent reason for referral to the pediatric cardiologist (heart specialist in children).
In young adults, approximately 55-70% of these murmurs are clinically insignificant; that is, they are not causes for emergency (Rajakumar et al., 1999).
The prevalence of heart murmurs in neonates varies from 0.6% to 77%. Most of these reports originate from early studies, predating echocardiography and interventional cardiology, which have improved the correctness of congenital heart disease diagnosis.
Half of these murmurs in neonates are due to an underlying cardiovascular malformation. According to a published article by Hoffman and Kaplan, 2002, the incidence of congenital heart disease (CHD) varies from 4-in-1000 to 50-in-1000 live births. Roguin N.
In his article titled “High prevalence of muscular ventricular septal defect in neonates,” stated that the wide variation in the incidence of CHD is due to the ability to detect trivial lesions, notably small muscular ventricular septal defects.
Risk Factors of Heart murmurs
There are countless risk factors associated with heart murmurs. Some of the common risk factors include:
- Heart attacks and Heart failure.
- Medical conditions such as High blood pressure, pulmonary hypertension, chromosomal abnormalities (Down’s syndrome), and hyperthyroidism.
- Congenital heart defects.
- Heart valve disease.
- A blood disorder marked with a high number of white blood cells called eosinophils (hypereosinophilic syndrome).
- Endocarditis (infection of the heart’s lining).
- Some autoimmune diseases such as lupus (SLE).
- Family history of Rheumatic fever.
- Family history of heart defects.
- Family history of heart murmurs.
- Certain cancers such as carcinoid.
- Medications such as Fen-phen.
- Some women who develop German measles (rubella) or uncontrolled diabetes during pregnancy are also likely to be at a higher risk of having babies with heart murmur conditions.
Causes of Heart Murmur
The etiology of heart murmurs is widely varied. It can be heard as a systolic murmur (when the heart contracts) or as a diastolic murmur (when the heart relaxes). Persons who have a healthy heart can sometimes have murmurs.
With modern advancements in medical technology, doctors can tell the difference between varieties of heart murmurs by the sound they make, and doctors can identify murmurs that might be linked to a problem with your heart.
Some heart murmurs are heard due to a problem with one of the heart’s valves. Heart valve defects can be minor and not cause broader health problems. But there can arise more severe problems that may need treatment- for instance, if the heart valve is narrowed, leaking, or prolapsed (weak of floppy).
Other noted and reported causes of heart murmurs, and other abnormal heart sounds include:
- Congenital malformations: Mostly in children, heart murmurs may be caused by a congenital heart malformation. These can be benign and cause no further complications or symptoms, or they can be severe malformations that require surgery or even a heart transplant. Some innocent murmurs (harmless) include a venous hum, a Still’s murmur, and pulmonary flow murmurs.
- Tetralogy of Fallot is one of the severe congenital problems that cause heart murmurs in children. Tetralogy of Fallot is a group of quadruple defects that co-occur in the heart that led to cyanosis episodes (a condition when the child’s skin turns blue from lack of oxygen) during an activity such as feeding and crying.
Another heart condition that causes a murmur is patent ductus arteriosus (PDA), a situation where a connection between the aorta and the pulmonary artery fails to close correctly after birth.
Some other congenital causes of heart murmurs include:
- Coarctation of the aorta
- Holes in the heart (severity depending on size and location of hole)
- Cardiac shunts
- Atrial septal defect
- Ventricular septal defect
Heart Valve defects
The heart has four valves, the aortic, tricuspid, mitral, and the pulmonary valve. Heart murmurs in adults are usually a result of problems with heart valves.
Causes of heart valve defects may include infection, such as infection cases of endocarditis, valve calcification, and rheumatic fever. Valve issues can also occur as part of the aging process; due to wear and tear, thickening, or stiffening of the heart.
When the valves do not close properly, regurgitation or backflow may occur:
- The aortic valve can have aortic regurgitation.
- The tricuspid valve can have regurgitation, usually caused by an enlargement of the right ventricle.
- The mitral valve can either experience an acute case of regurgitation caused by a sudden infection or heart attack or a chronic regurgitation caused by high blood pressure or a mitral valve prolapsed.
- Pulmonary regurgitation is caused by a backflow of blood into the right ventricle when the pulmonary valve cannot close completely.
Stenosis is the stiffening or narrowing of the heart valves. The heart has four valves, and each of these valves can develop stenosis in different ways:
- Aortic stenosis can occur because of rheumatic fever, and it may cause heart failure.
- Tricuspid stenosis usually occurs because of rheumatic fever or a heart injury.
- Mitral stenosis can also be caused by rheumatic fever, a complication of scarlet fever, or strep throat. As a result of mitral stenosis, fluid can back up into the lungs, resulting in pulmonary edema.
- Pulmonary valve Stenosis is primarily a congenital problem, and it usually runs in families. Aortic and tricuspid stenosis can also be congenital.
- Another rare type of stenosis that causes heart murmur is caused by hypertrophic cardiomyopathy. In this case, the heart muscles thicken, which makes it more difficult for the heart to pump blood. This thickening results in heart murmurs. It also runs in families.
Symptoms of Heart Murmur
Harmless heart murmurs are simply asymptomatic. Depending on the cause of a severe heart murmur condition, signs and symptoms may include:
- Swelling of the feet or legs and sudden weight gain
- Skin appearing blue, mostly on fingertips, lips, and joints.
- Shortness of breath after mild exercises
- Chronic cough
- Enlarged liver.
- Enlarged neck veins.
- In infants and children, poor appetite and failure to grow normally.
- Heavy sweating with no or less activity
- Chest pain
- Increased heart rate or heart palpitations
- Dizziness and lightheadedness
Diagnosis of Heart Murmurs
The primary diagnosis for heart murmurs is using a stethoscope to listen and observe patients’ heartbeats by a doctor. To confirm if the murmurs are harmless or detrimental, a cardiologist (a doctor specializing in heart conditions and treatments) takes note of the loudness of the murmurs and heartbeat phases in which the murmur occurs, the pitch of the sound.
He also checks if he can hear the heart murmurs in the neck or back and whether the sound changes with body position.
If a detrimental abnormal heart sound is suspected, confirmation is deduced with further testing. Tests may include:
- Cardiac MRI: For a scan to examine the structure of the heart.
- Blood tests: To ascertain levels of blood cells and increased levels of blood antibodies.
- Electrocardiogram (ECG): This test records the heart’s electrical activity.
- Echocardiogram: This is a test that entails an ultrasound scan of the heart
- Chest X-ray: To observe the size of the heart.
The doctor will subsequently look for other signs and symptoms of heart problems and investigate the medical history of a patient and his/her family to exclude a differential diagnosis of heart murmurs.
He may also listen to the patient’s lungs and examine if a patient has signs of liver enlargement. These symptoms, observations, and routine checks provide information about the type of heart problem a patient is experiencing.
Some other heart conditions might present similar symptoms as heart murmurs, and they can also serve as causes of heart murmurs.
These conditions or disease may include:
- Flow thyrotoxicosis
- Pregnancy anemia
- Stenosis of the heart valves
- Hypertrophic cardiomyopathy
- Aortic Coarctation
- Systolic Ejection
Other Abnormal Heart Sounds
Some other abnormal heart sounds that are different from normal heart sounds and heart murmurs that can occur due to complications or abnormalities in heart functions include:
A heart click is caused by problems associated with the mitral valve. Prolapses of the mitral valve are a common cause of heart clicks. It occurs when one or both flaps of the mitral valve are too long. These long flaps cause some blood to regurgitate into the left atrium.
This case is sporadic. It is a galloping rhythm of the heart with a third or fourth heartbeat. This heart has a regular two beats (S1 and S2), a third beat (S3 sound) is a sound that occurs after an S2 diastole “dub” sounds.
It is likely to be caused by an increased amount of blood within the ventricle. This S3 sound is most often harmless in young athletes and pregnant women, but in an older adult, it can indicate underlying heart problems, such as Cognitive Heart Failure.
If present, an S4 sound is an extra sound before the S1 systole “lub” sound. It is a result of blood forced into a stiff left ventricle. An S4 beat is a sign of severe heart problems.
These are caused by frictions between the layers of the pericardium, a lining sac around the heart. These frictions usually are caused by infection of the pericardium due to a bacteria or virus.
Treatment of Heart Murmurs
A harmless heart murmur does not require any treatment because the heart is healthy. Suppose a heart murmur is presented as a complication of an illness, such as a fever or hyperthyroidism (an over-active thyroid gland). In that case, the murmur will go away immediately after such a condition is treated.
On the other hand, an abnormal murmur is closely monitored by the doctor over time. Treatment largely depends on the heart condition causing the murmur. These treatments may include medications and surgery. Some medications that the doctor might prescribe for a patient include:
Anticoagulants are also known as blood thinners. This group of medications prevents blood clots from forming in the heart, which causes a stroke. A cardiologist may prescribe common anticoagulants such as aspirin, clopidogrel (Plavix), and warfarin (Jantoven).
Direct-acting oral anticoagulants (newer blood thinners) are also prescribed. Examples of newer blood thinners include rivaroxaban (Xarelto), apixaban (Eliquis), and dabigatran (Pradaxa).
Angiotensin-Converting Enzyme (ACE) inhibitors
ACE inhibitors help to lower blood pressure. Hypertension and pulmonary hypertension worsen underlying conditions that cause heart murmurs.
Diuretics (water pills) reduce excess fluid from the body. Diuretics can help treat other conditions that might worsen a heart murmur.
These are drugs that lower the heart rate and blood pressure of a person. They are administered for some types of heart valve problems.
These are medications that help lower cholesterol levels in the body. Having high levels of cholesterol seems to worsen some heart valve problems, including some heart murmurs.
Antibiotics were medically recommended for most people with abnormal heart murmurs before visiting the cardiologist or having surgery to prevent pericardium- bacterial infection of the heart’s lining.
But recently, doctors no more recommend antibiotics before procedures, except for patients who have an artificial heart valve, heart valve infection history, or a congenital heart defect.
A damaged or leaky valve that causes a heart murmur may require surgery. Some of the heart valve treatments that may be recommended by a cardiologist, depending on the heart condition, include:
- Balloon valvuloplasty
- Valve leaflet repair
- Repair of structural support
- Options under this category include:
- Open-heart surgery
- Ross procedure
- Transcatheter aortic valve replacement (TAVR)
It is quite impossible to prevent heart murmurs. However, most murmurs are innocent (harmless) and may not cause any health complications. Treatments to manage underlying causes are available for people with an abnormal heart murmur. Individuals diagnosed with heart murmurs due to valve problems are at a higher risk of developing infections in the valves (endocarditis) during specific medical procedures due to the risk of bacteria entering the bloodstream. A doctor should be contacted immediately when any sign or symptom is noticed in a child or adult.
- Heart Murmur; https://www.cincinnatichildrens.org/health/h/murmurs
- What Are Heart Murmurs? https://www.webmd.com/heart-disease/guide/heart-murmur-causes-treatments.
- Heart Murmur: Symptoms & Treatments; https://healthcare.utah.edu/cardiovascular/conditions/heart-murmur.php
- Heart murmurs; https://medlineplus.gov/ency/article/003266.htm