What are heart sounds?
Heart sounds are generated by blood flowing in and out of the heart’s chambers through the valves as they open and close. Listening to the heart sounds through a stethoscope (auscultation) is one of the first steps a physician takes in evaluating a patient’s medical condition.
Heart sounds provide the doctor valuable information about heart function. Auscultation is used to detect abnormal heart sounds and decide on further course of action.
How does the heart function?
The heart is a muscular organ and has four chambers that receive and pump blood:
- Right atrium
- Right ventricle
- Left atrium
- Left ventricle
- The left atrium receives oxygenated blood from the lungs and pumps it into the left ventricle.
- The left ventricle pumps the oxygen-rich blood to the rest of the body through a network of arteries.
- The right atrium receives the oxygen-depleted blood from the body through veins and pumps it into the right ventricle.
- The right ventricle pumps the blood to the lungs for oxygenation.
The left ventricle’s contractions while pumping out blood create the systolic blood pressure in the arteries (the higher number in a blood pressure reading). A web of nerve tissue runs through the heart to send electric signals to the heart muscle to initiate the heart’s contraction.
Heart valves ensure that the flow of the blood is in only one direction, by opening and closing as the heart pumps blood. The four heart valves are
What creates the heart sounds?
Blood flow creates vibrations in the heart chambers and valves which produce audible sounds that can be heard through a stethoscope. Smooth, low-resistance blood flow is called a laminar flow. When the flow is rough with high resistance it is known as a turbulent flow.
Vibrations increase along with blood flow turbulence and depend on the diameter of the blood vessel as well as the blood’s
Some of the functions of the heart that generate heart sounds are
- Opening or closing of the heart valves
- Flow of blood through the valve opening
- Flow of blood into the heart’s ventricles
- Rubbing of cardiac surfaces
What are the four heart sounds?
The cardiac cycle is made of two phases:
- Systole while the ventricles contract to pump out blood
- Diastole when the ventricles relax and fill with blood.
These two phases constitute the heartbeat.
In a healthy adult, the heart makes two sounds, commonly described as ‘lub’ and ‘dub.’
The third and fourth sounds may be heard in some healthy people, but can indicate impairment of the heart function. S1 and S2 are high-pitched and S3 and S4 are low-pitched sounds.
When the two ventricles contract and pump out blood into the aorta and pulmonary artery the mitral and tricuspid valves close to prevent the blood flowing back into the atria. The first sound S1 is generated by vibrations created by the closing of these two valves.
Normally the mitral valve closes just before the tricuspid valve, and when the two different sounds are detectable, it is called a “split S1.” A split S1 may be indicative of certain conditions affecting the heart.
After pumping the blood, the ventricles relax to receive blood from the atria, and the diastole phase starts. The aortic and pulmonic valves close and cause vibrations, giving rise to the second heart sound, S2. The increase in intensity of this sound may indicate certain conditions.
When the aortic valve closes just before the pulmonic valve, it may generate a split S2. This may indicate impairment in the heart function.
The third heart sound is a low-pitched sound audible with the rapid rush of blood from the atrium into the ventricle as it starts relaxing. This may be a normal sound in some people but in people with heart conditions, S3 may indicate heart failure.
The fourth is a low-intensity sound heard just before S1 in the cardiac cycle. The sudden slowing of blood flow by the ventricle as the atrium contracts causes this sound, which may be a sign of heart disease.
Other heart sounds
Opening snap (OS) is a high-pitched sound that is caused by rapid opening of the mitral or tricuspid valve following the aortic valve closing sound (S2). This may indicate narrowing (stenosis) of the mitral or tricuspid valve; the closer in time the OS is to S2, the more severe the stenosis.
Ejection systolic sounds
These sounds are heard during the early part of the ventricular contraction, which may be
- Valvular ejection sounds due to defects in the aortic or pulmonic valves
- Vascular ejection sounds due to defects of the aortic or pulmonary artery
- Nonejection systolic click due to mitral or tricuspid valve prolapse
In some people, heart murmurs are just the sound of blood flow characteristic to that person. Doctors call this an “innocent heart murmur.” Heart murmur may also be caused by turbulent flow of blood across the heart valves, however, which may indicate heart disease.
Latest Heart News
Daily Health News
Health Solutions From Our Sponsors
Top What Are The Four Heart Sounds Related Articles
A-Fib SlideshowAFib symptoms like heart racing, fluttering, and irregular heart beat may be caused by heart disease, obesity, alcohol use, thyroid disease, and other conditions. AFib medications may include blood thinners, drugs to control heart rate or convert the heart to a normal rhythm. AFib surgery is also a treatment possibility.
Cholesterol Drugs SlidesWhen diet and exercise aren't enough, should you turn to drugs? Learn cholesterol basics, drug classes, and available drugs along with their benefits and side effects.
Congenital Heart DefectsCongenital heart defects are heart problems that are present at birth. Genetics may play a role in some heart defects. Symptoms can range from nonexistent to severe and life-threatening. Fatigue, rapid breathing, and decreased blood circulation are a few possible symptoms of congenital heart defects. Many cases do not require any treatment. Procedures using catheters and surgery may be used to repair severe heart defects.
Congestive Heart Failure (CHF)Congestive heart failure (CHF) refers to a condition in which the heart loses the ability to function properly. Heart disease, high blood pressure, diabetes, myocarditis, and cardiomyopathies are just a few potential causes of congestive heart failure. Signs and symptoms of congestive heart failure may include fatigue, breathlessness, palpitations, angina, and edema. Physical examination, patient history, blood tests, and imaging tests are used to diagnose congestive heart failure. Treatment of heart failure consists of lifestyle modification and taking medications to decrease fluid in the body and ease the strain on the heart. The prognosis of a patient with congestive heart failure depends on the stage of the heart failure and the overall condition of the individual.
Coronary Heart Disease Screening Tests (CAD)
Coronary heart disease or coronary heart disease (CAD) screening tests can be used to potentially prevent a heart attack or cardiac event in a person without heart disease symptoms, and can assist in diagnosing heart disease in individuals with heart disease symptoms. Examples of coronary heart disease tests include:
- electrocardiogram (ECC, EKG),
- exercise stress test,
- radionuclide stress test,
- stress echocardiography,
- pharmacologic stress test,
- CT coronary angiogram, and
- coronary angiogram.
Heart CT ScanEBCT (also referred to as a calcium-score screening heart scan). This test is used to detect calcium deposits found in atherosclerotic plaque in the coronary arteries of heart disease patients. The more coronary calcium means more coronary atherosclerosis, which can raise the risk of future cardiovascular problems.
Heart Attack (Myocardial Infarction)A heart attack happens when a blood clot completely obstructs a coronary artery supplying blood to the heart muscle. A heart attack can cause chest pain, heart failure, and electrical instability of the heart.
Heart Attack PreventionHeart disease and heart attacks can be prevented by leading a healthy lifestyle with diet, exercise, and stress management. Symptoms of heart attack in men and women include chest discomfort and pain in the shoulder, neck, jaw, stomach, or back.
Heart Attack Symptoms and Early Warning Signs
Recognizing heart attack symptoms and signs can help save your life or that of someone you love. Some heart attack symptoms, including left arm pain and chest pain, are well known but other, more nonspecific symptoms may be associated with a heart attack. Nausea, vomiting, malaise, indigestion, sweating, shortness of breath, and fatigue may signal a heart attack. Heart attack symptoms and signs in women may differ from those in men.
Heart Disease SlideshowHeart disease prevention includes controlling risk factors like diet, exercise, and stress. Heart disease symptoms in women may differ from men. Use a heart disease risk calculator to determine your heart attack risk.
Heart Disease QuizTake our Heart Disease Quiz to get answers and facts about high cholesterol, atherosclerosis prevention, and the causes, symptoms, treatments, testing, and procedures for medically broken hearts.
Am I Having a Heart Attack? Symptoms of Heart DiseaseHeart attacks symptoms vary greatly for men and women, from anxiety and fatigue to nausea and sweating. Learn the warning signs of a heart attack and know the symptoms that may require an immediate trip to the hospital.
Heart Lead ExtractionThe heart disease lead extraction procedure is needed when your leads are not working properly. This can be caused by: damage to the inside (called a fracture) or outside of the lead,large amounts of scar tissue form at the tip of the lead, causing it to need more energy to function than your pacemaker or ICD can deliver. This condition is known as "exit block," infection at the site of the device and lead implant.
What Is a Heart Transplant?Heart transplant consists of three operations: 1) harvesting the heart from the donor, 2) removing the recipient's damaged heart, and 3) the implantation of the donor heart. The selection and distribution of donor hearts is a careful process so that the hearts are distributed fairly. For the patient requiring a heart transplant, all other important organs in the body must be in good shape. The most common complication of heart transplant is organ rejection.
Heart Valve Disease SurgeryHeart valves that are diseased can be treated both surgically (traditional heart valve surgery) and non-surgically (balloon valvuoplasty). The mitral valve is the most commonly repaired heart valve, but the aortic, pulmonic, and tricuspid valves may also undergo some of these repair techniques.