Proper use of the stethoscope: three heads and one tale.

Years ago I heard a story about a sage practitioner who was making teaching rounds. The house staff watched as he listened to the patient's heart with his stethoscope for perhaps 5 minutes. He then stood up to stretch his back and a resident asked him what he thought about the heart murmur. The practitioner responded, “What murmur? I'm still listening to the first heart sound.” Contrast this with my experience in getting a pre-induction physical examination for the Army. At the time, I was completing my residency in internal medicine. The rather old physician who was examining my heart placed the stethoscope carefully over 4 areas of the chest and passed me on as normal. He seemed unaware that he did not have the ear pieces of the stethoscope in his ears, but rather around his neck. I said not a word, as I knew that my heart sounds were normal. One often sees practitioners examine a patient briefly in one posture, and without removing the patient's clothing. Typically, they put the stethoscope in one or two spots on the front of the chest, over clothing or hospital gown, and listen for a very few cardiac cycles before concluding, “S1, S2 normal, no murmurs.” Brief to the point of incompleteness, such a note disregards the rest of the cardiovascular examination. Cursory examinations provide little more certainty than did my armed forces pre-induction physical examination, when the examiner couldn't possibly hear any heart sounds. The creation of the stethoscope in 1816 by Rene Laennec resulted from the need to better hear the sounds that emanate from the body. By amplifying a sound's frequency and intensity, this device improved diagnosis. However, it was not long before doctors noted frustrating difficulties in the proper use of the stethoscope. Sounds could be distant or difficult to appreciate because of their pitch or the shape of the patient's chest. Some auscultations were especially challenging because of multiple abnormal sounds and murmurs. There was also the need for the doctor to have good hearing. Improper use of technology led Oliver Wendell Holmes (the physician, not the Supreme Court justice) in 1848 to pen the poem “The Stethoscope Song,” in which he says, “Now use your ears, all you that can/But don't forget to mind your eyes, …”1 Perhaps he was aware that in 1834 the London Times purportedly had the following to say about the stethoscope: That it will ever come into general use, notwithstanding its value, is extremely doubtful because its beneficial application requires much time and gives a good bit of trouble, both to the patient and to the practitioner because its hue and character are foreign and opposed to all our habits and associations. The advent and rapid evolution of echocardiography in the mid-20th century provided a more accurate noninvasive approach to cardiac diagnosis. Proper interpretation of the test results could yield information not attainable with a stethoscope alone. The traditional emphasis on clinical skills for bedside diagnosis changed to the ordering of an echocardiogram to evaluate murmurs or suspected heart disease. Indeed, some specialists in cardiology and cardiac surgery think the stethoscope should be abandoned. Yet others feel that the problem lies really with the practitioner's not knowing enough about the proper use of the stethoscope.2 An adage states that the problem isn't silence but deafness. The examiner must train the ear to hear and the brain to think about the examination while doing it. Hearing one murmur should direct the examiner to listen for other murmurs and abnormal heart sounds. Here are some examples from my own experience: It is not enough to hear the murmur of aortic insufficiency and then order an echocardiogram, which might or might not adequately visualize the ascending aorta. It is important to listen to the murmur on both sides of the sternum. If it is louder along the lower-right sternal border than to the left, aortic root disease becomes more likely than aortic valve disease, and the subsequent echocardiogram requisition can ask for a more careful look at the aortic root. In addition, a better determination of the degree of aortic insufficiency can be made by listening for “runoff signs,” rather than by relying on the intensity or duration of the murmur, which can be influenced by such things as blood pressure, blood volume, left ventricular dysfunction, and the size of the chest. Hearing aortic insufficiency should prompt a search for an Austin Flint diastolic flow rumble, an apical S3, Duroziez murmur, Quincke pulse, pistol shots, bounding pulses, wide pulse pressure, or a carotid bisferious pulse. Finding such runoff signs is especially important when the echocardiogram report says “mild aortic insufficiency.”3 In that case, either the echocardiographic report is wrong or the patient has a peripheral arteriovenous fistula that needs to be found. Moreover, how does the clinician distinguish a murmur of mitral stenosis from an Austin Flint rumble? One way is to listen at the apex for an opening snap or an S3. An opening snap indicates authentic mitral stenosis, whereas an S3 cannot occur in a left ventricle when mitral stenosis prevents rapid enough left ventricular inflow. Therefore, a mitral diastolic murmur with an S3 rather than an opening snap suggests an Austin Flint rumble. Noting—in a patient with a Starr-Edwards caged ball valve—that the prosthetic sound is a dull thud, rather than a high-frequency click, points to ball variance.4 In support of mitral valve prolapse: an early systolic click occurs earlier still when the patient stands, and later when the patient lies supine and his legs are raised passively. Not everything that clicks, however, is prolapse. A split opening snap indicates both mitral and tricuspid stenosis. The summation gallop can be separated into distinct S3 and S4 sounds by slowing the heart rate with carotid massage. On the other hand, hearing what appear to be an S3 and an S4 when the heart rate is slow might suggest that there are two S4 sounds, caused by 2:1 heart block. On hearing an apical S4, one can amplify the diagnosis by palpating the S4 while concomitantly feeling a double systolic apical impulse: such a triple impulse indicates hypertrophic obstructive cardiomyopathy. Hearing a split S2 at the cardiac apex in a patient with dyspnea is an important clue to pulmonary hypertension.5 Hearing a fixed split of S2 in a patient with a complete left bundle branch block indicates fixed paradoxical splitting and the coexistence of heart failure. When searching for the diastolic murmur of mitral stenosis, an Austin Flint rumble, or the tricuspid flow murmur of a large left-to-right shunt through an atrial septal defect, one typically listens with light pressure, using the bell of the stethoscope. However, there is a useful trick if you encounter difficulty perceiving such low-frequency sounds. Try to feel the sound on the eardrums as a vibration. In other words, try to palpate it with your tympanic membrane. These murmurs, an S3 or an S4, may be better felt than heard.* These illustrations demonstrate that the proper use of the stethoscope can be self-reinforcing, as confidence in the findings improves one's trust in the examination. Accordingly, doctors can become less reliant on technology such as echocardiography, which is often not available in the middle of the night or in the office. Moreover, the findings on physical examination will often clarify the questions that subsequent testing needs to help answer. For example, hearing a fixed split of S2 might suggest ordering a bubble study to search for an atrial septal defect when the echocardiogram is available. Obviously there are other uses of the stethoscope besides the cardiac examination. Laennec was particularly interested in listening to the lungs, including searching for signs of tuberculosis “in the summit of the lungs … below the clavicle.”6 Consider other auscultatory findings that the stethoscope can help elicit: vascular bruits including arteriovenous fistulae, hepatic and splenic friction rubs, the succession splash of a lesser-space infection in the abdomen, a thyroid bruit, crepitus in various locations (some crepitations are also palpable), bowel sounds in a scrotal hernia, bruits from internal or external renal artery compression, bruits of pulmonary artery branch stenosis or coarctation of the aorta, flow murmur in grafts, a venous hum, and a pericardial rub or knock. Systolic bruits that extend into diastole indicate tight arterial stenosis, and such bruits must be distinguished from the continuous murmur of an arteriovenous fistula.7 Our new curriculum at the Northwestern University Feinberg School of Medicine emphasizes this with its competency-based educational structure. In conclusion, the stethoscope has 3 heads—the bell, the diaphragm, and the one between the earpieces. Using all three properly forms the tale.