Cardiovascular diseases are a significant cause of disease and the leading cause of death worldwide. But one of the main aspects of cardiovascular disease is that its complications are usually very sudden after a chronic and very slow progression. That’s why cardiovascular system evaluation should always be a part of the physical examination, even in patients who do not report cardiovascular symptoms.
Auscultation relies on a stethoscope to listen to heart sounds, providing important insight about heart function, heart valves, main arteries, and other aspects that cannot be evidenced in plain sight.
Heart murmurs are one of the most critical physical signs of the cardiovascular system. They are sometimes very dangerous or not problematic at all. Some of them only appear in particular circumstances while others are maintained for a long time. Doctors can find them for the first time in older adults with fragile health, but also in otherwise healthy children. For these reasons, heart murmurs deserve complete chapters in medicine books and an entire article, to say the least.
Overview
Heart murmurs are abnormal heart sounds resulting from a turbulent flow of blood across the blood vessels or heart valves. They are triggered by:
- Abnormally high blood flow speed passing through blood vessels or heart valves
- Normal blood flow speed passing through an irregular or constricted space before entering into a larger chamber
- Regurgitant or backward blood flow passing through an abnormal heart valve
It is a physical sign like fever, which can be very high or almost impossible to perceive, intermittent or continuous, associated or not with chills, and can be triggered by multiple causes. Like any other sign, the only way to know why it is showing up is by registering the sound’s timing, duration, and character. Other characteristics include its irradiation to other body parts and maneuvers that increase or decrease the sound.
Causes
Heart murmurs are only a sign evaluated by doctors in the physical exam. Just like fever, bruises, and edema, there are multiple diagnoses we can consider in the presence of murmurs. These are the most important:
Aortic insufficiency
It is a type of valvular disease that compromises the aortic valve. The valve does not close appropriately, and the blood flow becomes compromised. It is sometimes a structural problem of the aortic valve but can also be caused by certain medications, especially dopamine agonists. When the problem is acute, it causes a murmur heard in the left sternal border, louder when the patient is leaning forward or sitting. When the problem is chronic, the heart murmur is high-pitched, located in the diastole and the same sternal border.
Aortic stenosis
This is also a valve problem, sometimes from a congenital heart defect but also developed due to aging. Calcium depositions and scarring in the aortic valve restrict the movement and the correct blood flow through it. This causes a systolic murmur located in the second right intercostal space or the apex. These patients usually feel dizzy or have recurrent episodes of syncope, angina, fatigue, or dyspnea.
Hypertrophic cardiomyopathy
In this case, it is not a problem in the heart valves but the heart muscle, which becomes enlarged and thick. The ventricles are usually severely taken by the disease, and the available space is reduced. It is often associated with valve changes and stiffness of the left ventricular area. In these cases, the murmur is a late systolic heart murmur with a harsh sound located at the apex of the heart. It increases with the patient sitting down and decreases with squatting.
Mitral insufficiency
This is one of the most common valvular heart conditions. It occurs when the mitral valve does not close appropriately, and the heart is unable to pump efficiently. Patients often develop fatigue, shortness of breath, and associated symptoms. In severe cases, it causes pulmonary hypertension, heart failure, and other heart conditions. In these cases, the heart murmur sounds at the heart’s apex, starting loud and fading at the end of the sound.
Mitral prolapse
This is another common valvular heart condition, and it a closure problem of the mitral valve. The symptoms are not as severe as in mitral insufficiency, but patients may grow tired more easily because a small amount of blood is leaking back to the heart instead of moving forward. In these cases, the murmuring sound is mid-systolic and associated with a systolic click sound when the valve gives in.
Mitral Stenosis
Like aortic stenosis, in mitral valve stenosis, there’s a narrowing of the mitral valve orifice due to the deposition of calcium in this area. This is a common finding as a late-stage complication of rheumatic fever and causes a rumbling and low-pitched murmur sound located in the apex and heard when the patient is laying down on his left side.
Myxomas: This is a rare connective tissue tumor found in the heart and located in different parts depending on each case. They are more common in females, and their symptoms depend on the severity of the obstruction. The features of the murmuring sound are also variable depending on the location of the tumor.
Papillary muscle rupture: Papillary muscles are attached to the heart valves and are responsible for opening and closing them in every heartbeat. A break of these muscles is a fatal complication of myocardial infarction or endocarditis that causes severe blood regurgitation, and it is potentially fatal. Luckily, it is not common, and it is immediately perceived in the physical exam because the heart murmur is very loud.
Rheumatic fever with pericarditis: This is an inflammatory disease that occurs in patients with streptococcal pharyngitis. There’s a cross-reaction against bacterial proteins, and the immune system starts attacking normal heart tissue. This causes inflammation of the pericardium, one of the heart layers, which is known as pericarditis. In these cases, heart sounds are similar to a friction rub, and there’s a galloping sound instead of the normal heart sounds. Murmurs are systolic or mid-systolic, depending on the most affected heart valves.
Tricuspid insufficiency or stenosis: Similar to mitral valve insufficiency and mitral valve stenosis, the same can happen in the heart’s tricuspid valve. In these cases, the murmuring sound is high-pitched (in tricuspid insufficiency) or low-pithed and louder in inspiration (in tricuspid stenosis).
Prostatic valve replacement: After replacing valves with a prosthetic, some patients may develop a heart murmur depending on the valve. This is a variable outcome of the valve replacement surgery, and the nature of the sound depends on the location of the prosthetic valve, its composition, and the surgical technique.
Innocent murmurs in children: There is a variety of innocent murmurs found in babies and children. For example, still murmurs are located on the left side of the sternum at the same level as the nipple, and it quiets down when the child is lying on his stomach. A pulmonic murmur is located in the first left intercostal space, and there’s also a venous hum heard above the clavicles, which also quiets down when the child is looking sideways or down.
Types and diagnosis
As noted above, heart murmurs should be evaluated according to their timing, duration, character, irradiation, and other characteristics. That is the only way to take out information from them and use them to diagnose one of the diseases mentioned above.
We have different types of murmurs depending on when and where they appear. Thus, timing is fundamental for the differential diagnosis. We have systolic murmurs between the first and second heart sound or diastolic murmurs when they occur after the second heart sound and before the first sound of the next heartbeat. They can have different intensities depending on how loud they are.
- Systolic murmurs are caused by ventricular ejection problems or a mechanical issue with the systole. We can say that they are subdivided into two types: mid-systolic and holosystolic murmurs. The former has a crescendo or decrescendo sound (starting louder and decreasing intensity or vice versa), and the latter has the same intensity throughout the systole. The former is caused by valve stenosis in the aortic or pulmonic artery, and the latter is formed by valve regurgitation or a septal defect in the ventricular cavity.
- Diastolic murmurs are associated with a defect in filling the heart or a relaxation issue in the heart muscle. This type of murmur usually goes in a decrescendo and may or may not increase sound intensity at the end. They are caused by valve regurgitation in the aortic or pulmonic arteries or stenosis in the tricuspid or mitral valves.
The right way to diagnose the heart murmur’s timing requires listening to the murmur with a stethoscope, locating the point of maximum intensity, and palpating the carotid pulse at the same time. Every stroke of the carotid artery marks the start of the systole. Depending on how the examinator hears them, heart murmurs can have different intensities:
- Grade I when it is only heard in a very quiet room by an experienced doctor
- Grade II when it is easily heard by most doctors regardless of their experience
- Grade III when it is a loud murmur but does not cause a thrill
- Grade IV when it is a loud murmur and causes a thrill
- Grade V when the thrill is very noticeable, and the murmur can be heard by lightly placing the stethoscope on the chest
- Grade VI when the thrill is very noticeable, and the murmur can still be heard with a slight separation between the chest and the stethoscope.
Another fact of significant importance to diagnose this type of sound is the location of maximum intensity. Upon detecting a heart murmur, doctors would place the stethoscope in different chest areas to locate where it is heard the loudest. These areas are well-defined in physical medical exams. They include the aortic area, pulmonary area, tricuspid area, the heart’s apex, the heart’s base, the axilla, and the fourth left intercostal space. After locating the sound precisely, doctors also need to know if the sound radiates to other areas, usually the heart’s base or the axilla in mitral regurgitation and the left sternal border, the carotid arteries, or another blood vessel in aortic stenosis.
Another aspect of murmurs that contributes to the diagnosis is the character and the pitch. Some of them are high-pitched and more easily to be heard. Others are low-pitched and slightly difficult to perceive. They can have different characters or qualities, such as rumbling sounds, a blowing murmur, and a harsh, cooing, or musical character.
Finally, some doctors include a type of dynamic auscultation in the exam in which they evaluate the heart murmur in different positions and with a variety of maneuvers. They may ask the patients to inspire deeply, expire deeply, squat or stand up, raise a straight leg, and sometimes inhale a vasodilator substance known as amyl nitrate. These maneuvers, and comparing what happens with the sound in each case, give the examiner enough information to locate the source of the problem and order appropriate exams to confirm their findings.
Warning signs and treatment
Most heart murmurs are not an emergency, and they need additional tests to confirm or deny the findings made in the physical exam. However, it is possible to detect emergencies by considering warning signs such as:
- Respiratory distress
- Cyanosis
- Edema
- Abnormal electrocardiogram findings
- Finger clubbing
Diagnostic tests will be recommended, including electrocardiography, angiography, echocardiography, and treatment will be initiated after detecting the abnormality. It may include antibiotics, anticoagulant agents, a surgical replacement of an incompetent valve, or no treatment at all in innocent murmurs.