Heart Murmur

The world of sounds is fascinating, but heart sounds are not audible to most of us. Quite distinct from the lub-dub sound that your heart makes is the whooshing and swishing sound a doctor hears through his stethoscope. It is a murmur. Murmurs are heard when blood flow meets resistance or due to turbulent blood flow caused by valve defects. Let us explore these unheard sounds, their causes, and what they indicate.

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Types of heart murmurs

Based on when they happen in a cardiac cycle, murmurs are classified into

• Systolic murmur occurs when the heart muscle contracts or tightens
• Diastolic murmur occurs when the heart muscle relaxes
• Continuous murmur occurs during both contraction and relaxation of the heart muscle

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Usually, diastolic and continuous murmurs point to heart disease

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Systolic murmur

It is the extra sound that the doctors hear when the heart is pumping blood, a result of a turbulent blood flow.

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The heartbeat that we hear is the sound of valves closing

• The first sound is because of the closure of atrioventricular valves (mitral and tricuspid valves). 
• The second sound is due to the closure of semilunar valves (aortic and pulmonary valves).

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Systole is the first part of the heartbeat during which the atrioventricular valves close. The blood moving across the heart valve is the cause of this sound.

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Diastolic murmur

The extra sound occurs during the diastole, that is, when the heart relaxes between the beats.

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Difference between diastolic and systolic murmur

Diastolic murmurs occur when the heart relaxes between heartbeats and are often hard to hear.

Systolic murmurs occur when the heart contracts.

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Innocent heart murmurs

Heart murmurs that aren’t dangerous are called innocent murmurs. When the blood circulates normally through the heart’s chambers, valves, or blood vessels, innocent murmurs (also known as functional or physiologic murmurs) occur. 

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They occur during

• Childhood
• Exercise
• Growth spurts
• Pregnancy
• The first few days after a baby is born

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They often appear and disappear, getting louder when the heart beats faster.

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Causes of a heart murmur

Leaky heart valves

When the heart valve becomes damaged and fails to close completely, blood flows backward through the valve instead of moving forward. The sound of blood swooshing backwards creates a murmur.

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Narrow heart valves

A properly functioning heart valve opens fully to allow blood to move through the heart. When the heart valve becomes stiff and narrow, it fails to open, and the blood that is supposed to flow forward is obstructed. Consequently, 

• It takes a long time for the blood to pass through the valve 
• More pressure is needed to move it forward

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This forceful movement of blood through a narrow opening for an extended period creates an abnormal heart murmur. It is common among older adults who have hardened blood vessels and heart valves.

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Hole in the heart wall

May develop due to

•  Congenital disability: A baby born with a hole in the wall between the two heart chambers 
•  Acquired:  An adult may develop a hole after a heart attack or surgery 

They cause blood to leak through the abnormal opening between the heart chambers, and these abnormal blood flow patterns cause a heart murmur.

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Infectious diseases

• Bacterial endocarditis, an infection of the inner lining of the heart, causes a murmur.
• Rheumatic fever, caused by a Streptococcus (bacterial) infection, also damages the heart valve, potentially causing a murmur.

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Other causes

Not every murmur is associated with valve disease. Sometimes murmurs are temporary and are caused by a temporary increase in blood flow, such as during

• Exercise
• Pregnancy
• Hyperthyroidism
• Anemia
• Rapid growth spurts in children

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Symptoms of murmur

Innocent murmurs usually don’t cause any symptoms; however, abnormal murmurs cause symptoms, which include

• Blue or gray fingernails or lips
• Chest pain
• Persistent cough
• Dizziness
• Swollen liver
• Swollen neck veins
• Fainting
• Heavy sweating with little or no activity
• Shortness of breath
• Swelling or sudden weight gain

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Diagnosing heart murmurs

To better assess murmurs, the patient may be asked to hold their breath or change positions because some heart murmurs are more pronounced when a person is breathing and squatting compared to when they hold their breath or stand still.

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Tests required to detect a murmur are

• ECG measures electrical activity within the heart.
• Echocardiogram: A cardiac ultrasound that produces images of the heart, its valves, and adjoining blood vessels.
• Chest X-ray
• MRI: shows images of structures within the heart
• Cardiac catheterization is done when other tests are inconclusive. Catheterization involves inserting a thin tube into a blood vessel and threading it forward towards the heart to diagnose abnormalities.

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Loudness, location, and quality of the murmur provide clues about its cause. Loudness of the murmur is graded from 1 to 6

• Grade 1 is very faint
• Grade 2 Faint but audible
• Grade 3 Moderately loud and easily heard
• Grade 4 Loud and associated with thrill (vibration felt on the chest)
• Grade 5 Very loud, heard with a stethoscope, lightly touching the chest with a thrill
• Grade 6 is extremely loud, which can be heard without a stethoscope and even without touching the chest

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Treating murmurs

Not all murmurs require treatment. Treatment is required if a heart condition is causing a murmur. Various options to treat murmurs are:-

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Lifestyle changes

Lifestyle changes help us to deal with murmurs by

• Exercising 
• Reducing salt intake
• Limiting alcohol
• Quitting smoking
• Losing weight

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Medications

To treat the underlying heart condition, it is necessary to prescribe medications such as

• Statins to lower cholesterol
• Diuretics to reduce fluids and salts
• Aspirin and anticoagulants to prevent blood clots
• ACE inhibitors and beta blockers to lower heart rate and blood pressure

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Procedures, devices, and surgery

If no results are achieved by medication and aggressive treatment of the underlying heart problem, surgery is advisable.

• Balloon valvuloplasty is used to treat narrowed or stiff heart valves. A long, thin, flexible tube, a catheter, is directed through a vein from the groin to the heart valve that needs to be opened. A large balloon at the tip of the catheter is inflated, which opens the valve. The balloon is then deflated and removed.
• Heart valve repair is commonly performed on the mitral valve. It is a minimally invasive and robotically guided procedure that decreases complications and causes a quick recovery.
• Heart valve replacement: A bioprosthetic valve or a mechanical heart valve is used. Bioprosthetic valves do not contain metal; thus, blood thinners are not needed in the long term.
• Mechanical valves are composed of materials that can cause clot formation, requiring the use of blood thinners. Their major advantage is that they can last for years.

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Outlook for people with a heart murmur

Individuals with innocent heart murmurs don’t experience complications. Usually, in children, they disappear before adulthood.

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In cases of abnormal heart murmurs, the prognosis depends on the cause and severity of the problem. Most individuals require only monitoring if their condition does not worsen. Medication or surgery may be performed as needed to manage or improve their condition.

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Conclusion

Heart murmur is diagnosed in people of all ages, from newborns to children. A heart murmur is an unexpected sound a doctor hears with a stethoscope. Some murmurs indicate structural abnormalities within the heart, which cause problems with blood flow. They occur when valves do not open or close properly, preventing the blood from flowing through the heart.