Murmurs

The stethoscope is almost 200 years old, invented in 1816 by René Laennec, a French doctor who was clearly tired of pressing his ear to the naked chests and bosoms of his countrymen.  In those days—long before the invention of antiperspirant, Dove soap, and daily hygiene—doctors who wanted to auscultate (medical term for listen to) the heart or lungs had to assume a posture of intimacy that in today’s world would result in immediate revocation of one’s medical license and a hefty lawsuit.  In the early 19th century it was entirely expected that a doctor would press his head to someone’s chest even if the patient hadn’t taken a bath since Napoleon was in grammar school.  “Doctor, after you treat my crabs and lice would you mind taking a close listen to my heart?  Merci.”

Some physicians protected themselves from tossing their croissant lunch by carrying with them handkerchiefs that served as a barrier between them and the skin of those in their care.  Others simply disregarded auscultory examination of the heart and made guesses about the cardiac condition based on clues from other parts of the body.

Dr. Laennec struck upon the idea of the stethoscope not so much for sanitary reasons, but rather out of practical considerations and to avoid offending the Victorian sensibility of a young female patient (with “great degree of fatness”) he was tasked to visit:

In 1816, I was consulted by a young woman laboring under general symptoms of diseased heart, and in whose case percussion and the application of the hand were of little avail on account of the great degree of fatness. The other method just mentioned [direct auscultation] being rendered inadmissible by the age and sex of the patient, I happened to recollect a simple and well-known fact in acoustics, . . . the great distinctness with which we hear the scratch of a pin at one end of a piece of wood on applying our ear to the other. Immediately, on this suggestion, I rolled a quire of paper into a kind of cylinder and applied one end of it to the region of the heart and the other to my ear, and was not a little surprised and pleased to find that I could thereby perceive the action of the heart in a manner much more clear and distinct than I had ever been able to do by the immediate application of my ear.

And, with that, the stethoscope—a device carried by doctors of nearly every specialty for a hundred years—was born, although the new-fangled device was not immediately accepted widely (as cited in Wikipedia):

Not all doctors readily embraced the new stethoscope. Although the New England Journal of Medicine reported the invention of the stethoscope two years later, in 1821, as late as 1885 a professor of medicine stated, "He that hath ears to hear, let him use his ears and not a stethoscope."

 

These days most doctors (dermatologists excluded) accept the stethoscope as a useful tool that is indispensable in the thorough examination of the patient.  While you can listen to lots of different body parts with the stethoscope, my interest lies mostly with the heart and it’s this subject that I’d like to briefly discuss.

I own several stethoscopes (and have lost several, too) that I stash in my various offices and in the trunk of my car (for emergency calls to the hospital—I’d hate to have to resort a rolled-up piece of paper if I don’t have a stethoscope at hand).  The fanciest of them is an electronic model that is meant to magnify the meaningful sounds (lub-dub) and suppress the ambient noise that interferes with examination.  I find this works better in theory than reality, but it looks cool.

When I listen to a patient’s heart I can tell a few things.

1. Rhythm.  Generally it’s fast, slow, or normal.  The timing of the beats is also important.  Most people have a pretty steady heart rate with beats as regular as a clock.  Others (those with atrial fibrillation or premature beats) will have a chaotic, unpredictable pattern.  Feeling a wrist pulse will provide the same information (helpful hint to all dermatologists who have forgotten which end of the stethoscope fits in the ears).
2. A generalized idea about the structure and function of the heart.  A large, weakened heart will result in a palpable contraction that is larger and slower than it should be.  Since the “lub-dub” sound we’re all familiar with arises from the slamming shut of heart valves, we can get a sense of the functional integrity of these structures by listening for changes in what we usually hear.  Additional sounds (murmurs, clicks, rubs, plops, gallops—unusual names for unusual sounds) can provide additional clues to valve and muscle dysfunction.

Many patients have been told at one point or another that they have a murmur, yet few know exactly what this implies.  The term murmur arises from Latin and means a soft utterance spoken under the breath.  This term is not the strangest in the auscultory lexicon.  A particularly loud murmur can produce a vibratory sensation called a thrill that can be felt by the examiner.  In such a case the clinician might ask permission to “palpate your chest for a thrill,” although I would strongly discourage such communication unless the doctor enjoys catching a right hook to the jaw.

In the medical world a murmur is the sound that blood makes when it flows through the heart in a turbulent manner.  Normal flow of blood through the heart valves is smooth and quiet.  In the healthy heart, the valves open widely (when blood traverses into the next chamber or artery) and close tightly (in order to keep blood from leaking back the wrong way).  If a valve fails to open adequately (possibly due to calcification or scarring) the flow through the valve becomes turbulent, much like the flow of water through a garden hose with a pinch in it.  This sound can be perceived as a quiet “whooshing” noise heard in the chest over the region where that valve is found.  Similarly, blood leaking back through a valve or across a septal defect produces a comparable, although distinct, sound.  The most common abnormal murmurs in adults relate to narrowing of the aortic valve or leakage back through the mitral valve (click here to listen to murmurs of aortic stenosis, mitral regurgitation, and ventricular septal defect)

The soft utterances of heart murmurs can imply problems with the valves or can be what we call physiologic, functional, or innocent—all ways of saying that the murmur doesn’t correspond to any significant structural or functional abnormality.  This is the most common murmur heard in children and pregnant women.  In infants, the turbulence arises from the blood flow through the pulmonary artery, a structure that is small and not fully developed at birth.  This murmur will typically disappear by 6 months of age.

In pregnant women, the mother’s cardiac output increases dramatically in order to support the metabolic demands of the fetus and it’s this increased flow that produces turbulence.  If I listen hard I can hear a murmur in most pregnant women I examine.  In what is perhaps the most strangely named of all chest sounds, the mammary soufflé is a murmur heard in about 15% of pregnant women and is thought to arise from prominent blood flow through the mammary arteries.

Conditions of exaggerated blood flow can arise in patients other than neonates and expecting mothers.  Adults with otherwise healthy hearts can develop a physiologic murmur if they suffer from illnesses—such as overwhelming infection or severe anemia—that drive the heart to beat harder and faster.  These unusual sounds will dissipate once the patient recovers and the cardiac output returns to normal.

Careful auscultation by an experience doctor can generally differentiate innocent murmurs from those that require further investigation.  Any sound that doesn’t fit the mold of the benign murmur can be easily clarified with an echocardiogram (cardiac ultrasound).

As you can see, many of us either have a murmur or have had a murmur at some point in our lives, and anything out of the ordinary won’t remain a mystery for long in the world of modern echocardiography.  So, there’s no need for you to freak out if your doctor diagnoses a quiet murmur after he carefully presses his ear to your chest.

Or, maybe there is.