Have you ever tried to listen to a patient’s heart sounds, and you can’t hear a thing? No lub (S1), no dub (S2). This may occur for a variety of reasons (heart failure with reduced ejection fraction, chronic lung disease, and a large body habitus, to name a few). You know the patient has a beating heart because they are walking and talking – but you hear nothing! Here are some tips for best practices for hearing distant heart sounds. Much of this will likely be a review; however, it never hurts to go back to the basics when you can’t hear heart sounds well. After all, do you really want to document “no heart sounds” in the medical record for a patient who is talking to you?
Tips on checking heart sounds
Removing any distracting noise
My first tip is to ensure that you maximize your potential to hear the loudest heart sounds possible by removing any distracting noise from the environment. This means turning off any ambient noise in the room (turn TV volume to mute, asking bystanders to mute devices, and pausing conversation with others). I also close my eyes when listening to heart sounds which, in addition to helping me hear things better, also reminds others not to talk. If the patient or bystanders start talking I slowly place my pointer finger on my lips to indicate that I am listening to their heart and need silence.
Check on bare chest wall
Second, make sure you are palpating landmarks on the chest and listening to heart sounds on the bare chest wall (not through clothing, for example). Placing the stethoscope on the bare chest wall optimizes hearing heart sounds and helps when visualizing the chest to palpate and auscultate the five landmarks on the chest. Next, locate the point of maximal impulse (PMI). As the name implies, this is the place on the chest where heart sounds should be the loudest. The PMI also referred to as the apical pulse, is at the bottom (apex) of the heart, typically at the 5th intercostal space at the mid-clavicular line. Some patients may have a displaced PMI. For example, patients with dilated cardiomyopathy who have a very large (thin) left ventricle have their PMI laterally displaced to the left (under the axilla). If you have difficulty locating the PMI, double-check to make sure your fingers are gently palpating the area (versus pushing hard into the intercostal spaces). Once you locate the PMI, gently place your stethoscope on the area and listen carefully.
Stethoscope placement
Once in position, I find it helpful to tilt my chin down as the earpieces of my stethoscope slowly adjust to the best listening angle. The earpieces should be at a 15° angle pointing towards the bridge of your nose (in the direction of your ear canals). Next, as one hand remains on the stethoscope, I place the other hand on the patient’s radial pulse to compare the (distant) heart sounds to the patient’s peripheral pulse. Comparing the peripheral pulse with what sounds like very distant heart sounds helps me concentrate on listening for S1 (lub) and S2 (dub). If S1 and S2 remain distant (or you can’t hear anything), have the patient lean forward if in the sitting position. Then have them lie down and listen to heart sounds in the left lateral position. Both maneuvers help bring the heart closer to the chest wall to help auscultate the heart sounds better. Another technique to help auscultate heart sounds better is to have the patient stop breathing for a few seconds to remove artifact from breath sounds. I find it helpful to say to the patient: “don’t breathe” (versus “take a deep breath). Then, within a few seconds, I indicate to the patient: “you can breathe now.”
Beyond listening to the PMI (to identify S1 and S2, heart rate, and rhythm), it is important to systematically listen to heart sounds in five landmarks on the chest wall to assess for murmurs, rubs, or gallops. I typically start with this by auscultating heart sounds while the patient is sitting up, then have them lie down to listen while flat (or at an angle if the patient can’t lie flat due to dyspnea) before having them lie in the left lateral position. The first place to listen is the second intercostal space to the right of the sternal border (hears the aortic valve best). Then move to the second intercostal space to the left of the sternal border (to hear the pulmonary valve best). Moving down to the 4th intercostal space to the left of the sternal border I locate and listen to the tricuspid valve before moving to the final landmark (the 5th intercostal space at the mid-clavicular line) to hear the mitral valve at the apex (or PMI) of the heart. As noted above if the heart is displaced to the left the PMI may extend to being under the axilla.
Once heart sounds (S1, S2) are identified it is important to determine if the patient has extra heart sounds or a murmur. If either is detected, it is essential to determine where in the cardiac cycle the extra sound or murmur is. To determine this, auscultate heart sounds while palpating the carotid upstroke, typically on the side closest to the examiner. For example, I typically stand on the right side of the patient so I gently palpate the patient’s right carotid artery while listening to heart sounds when the patient is in the supine position. S1 should coincide with the carotid pulse.
Interestingly, I have found what I think is S1 is in fact, S2 once I simultaneously palpate the carotid pulse. For example, I have often heart 3 heart sounds in the pulmonic area. To determine if an S4 versus a split S2 I need to palpate the carotid pulse to make sure the extra heart sound is after S2 (before S1). Once that is confirmed, I have the patient take a deep breath to see if the sound varies with breathing (typically a split S2). I then ask myself which extra sound are they likely to have given the patient’s history. For example, if they have long standing hypertension and the sound doesn’t change with breathing, it is likely an S4. I have also found that S4s are as “loud” as S1 and S2; and S4s can’t occur in a patient with atrial fibrillation (because they have not distinct atrial contraction). Or if the patient has a left bundle branch block and the sound changes with breathing the patient is more likely to have a split S2. The same holds true for heart murmurs. It is important to determine where the murmur is best heard (location) and where is relation to the cardiac cycle the murmur occurs (before, during, or after S1; or through out the whole cycle). Granted hearing extra heart sounds and murmurs are icing on the cake if you started with distant heart sounds that would nearly (or totally) undetectable at the first attempt, hopefully these tips have reinforced your skills to listen to heart sounds better.
If all else fails, before you even contemplate documenting distant heart sounds (when in fact nothing is heard), have a colleague listen to the patient to see where they hear the heart sounds best – or if at all!
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