Auscultation
1. Become comfortable with your stethescope.
2. Engage the diaphragm of your stethescope and place it firmly over the 2nd right intercostal space, the region of the aortic valve. Then move it to the other side of the sternum and listen in the 2nd left intercostal space, the location of the pulmonic valve. Move down along the sternum and listen position the diaphragm over the 4th intercostal space, left midclavicular line to examine the mitral area. These locations are rough approximations and are generally determined by visual estimation.
3. In each area, listen specifically for S1 and then S2. S1 will be loudest over the left 4th intercostal space (mitral/tricuspid valve areas) and S2 along the 2nd R and L intercostal spaces (aortic/pulomonic valve regions).
4. Note that the time between S1 and S2 is shorter then that between S2 and S1. This should help you to decide which sound is produced by the closure of the mitral/tricuspid and which by the aortic/pulmonic valves and therefore when systole and diastole occur.
5. Compare the relative intensities of S1 and S2 in these different areas.
6. In younger patients, you should also be able to detect physiologic splitting of S2. That is, S2 is made up of 2 components, aortic (A2) and pulmonic (P2) valve closure. On inspiration, venous return to the heart is augmented and pulmonic valve closure is delayed, allowing you to hear first A2 and then P2. On expiration, the two sounds occur closer together and are detected as a single S2. Ask the patient to take a deep breath and hold it, giving you a bit more time to identify this phenomenon. The two components of S1 (mitral and tricuspid valve closure) occur so close together that splitting is not appreciated.
7. You may find it helpful to tap out S1 and S2 with your fingers as you listen, accentuating the location of systole and diastole and lending a visual component to this exercise. While most clinicians begin asucultation in the aortic area and then move across the precordium, it may actually make more sense to begin laterally and then progress towards the right and up as this follows the direction of blood flow. Try both ways and see which feels more comfortable.
8. Listen for extra heart sounds. While present in normal subjects up to the ages of 20-30, they represent pathology in older patients. An S3 is most commonly associated with left ventricular failure and is caused by blood from the left atrium slamming into an already overfilled ventricle during early diastolic filling. The S4 is a sound created by blood trying to enter a stiff, non-compliant left ventricle during atrial contraction. It's most frequently associated with left ventricular hypertrophy that is the result of long standing hypertension.
9. Either sound can be detected by gently laying the bell of the stethoscope over the apex of the left ventricle (roughly at the 4th intercostal space, mid-clavicular line) and listening for low pitched "extra sounds" that either follow S2 or precede S1. These sounds are quite soft, so it may take a while before you're able to detect them.
Type / Inspiration / Expiration / CauseNormal or physiologic
Wide, fixed splitting / Atrial septal defect
Wide split, varies with inspiration / Pulmonary stenosis, RBBB
Paradoxical splitting / Hypertrophic cardiomyopathy
Listening for Extra Heart Sounds
Positioning the patient on their left side while you listen may improve the yield of this exam. The presence of both an S3 and S4 simultaneously is referred to as a summation gallop.
Murmurs
These are sounds that occur durin g systole or diastole as a result of turbulent blood flow. Traditionally, students are taught that auscultation is performed over the 4 areas of the precordium that roughly correspond to the "location" of the 4 valves of the heart.
Valves are not strictly located in these areas nor are the sounds created by valvular pathology restricted to those spaces. So, while it might be OK to listen in only 4 places when conducting the normal exam, it is actually quite helpful to listen in many more when any abnormal sounds are detected.
If you hear a murmur, ask yourself:
a. Does it occur during systole or diastole?
b. What is the quality of the sound? It sometimes helps to draw a pictoral representation of the sound.
c. What is the quantity of the sound? The rating system for murmurs is as follows:
§ 1/6? Can only be heard with careful listening
§ 2/6? Readily audible as soon as the stethescope is applied to the chest
§ 3/6? Louder then 2/6
§ 4/6? As loud as 3/6 but accompanied by a thrill
§ 5/6? Audible even when only the edge of the stethescope touches the chest
§ 6/6? Audible to the naked ear
Most murmurs are between 1/6 and 3/6. Louder generally indicates greater pathology.
Intensity of Murmur
Grade 1 / just audible with a good stethoscope in a quiet roomGrade 2 / quiet but readily audible with a stethoscope
Grade 3 / easily heard with a stethoscope
Grade 4 / a loud, obvious murmur with a palpable thrill
Grade 5 / very loud, heard only over the pericardium but elsewhere in the body
Grade 6 / heard with stethoscope off chest
d. What is the relationship of the murmur to S1 and S2?
e. What happens when you march your stethescope from the 2nd RICS (the aortic area) out towards the axilla (the mitral area)? Where is it loudest and in what directions does it radiate? By moving in small increments you will be more likely to detect changes in the character of a particular murmur and thus have a better chance of determining which valve is affected and by what type of lesion.
Auscultation over the carotid arteries: In the absence of murmurs suggestive of aortic valvular disease, you can listen for carotid bruits (sounds created by turbulent flow within the blood vessel) at this point in the exam. Place the diaphragm gently over each carotid and listen for a soft, high pitched "shshing" sound. It's helpful if the patient can hold their breath as you listen so that you are not distracted by transmitted tracheal sounds.
The meaning of a bruit remains somewhat controversial. I was taught that bruits represented turbulent flow associated with intrinsic atherosclerotic disease and that the disappearance of a bruit which was previously present was a sign that the lesion was progressing. However, a number of studies provide evidence that atherosclerotic disease is frequently absent when a bruit is present as well as the reverse situation.
This is actually of clinical importance because recent data suggest that it may be beneficial to surgically repair carotid disease in patients who have significant stenosis yet have not experienced any symptoms. Thus, it is becoming increasingly important to determine the best way of identifying asymptomatic carotid artery disease... and carotid auscultation may, in fact, not be the mechanism of choice.
Identifying the Most Common Murmurs:
1. Systolic Murmurs: In the adult population, these generally represent either aortic stenosis or mitral regurgitation. To distinguish between them, remember the following: Murmurs of Aortic Stenosis (AS):
Tend to be loudest along the upper sternal borders and get softer as you move down and out towards the axilla. There is, however, a phenomenon referred to at the Gallavardin Effect which can cause murmurs of AS to sound as loud towards the axilla as they do over the aortic region. When this occurs, the shape of the sound should be similar in both regions, helping you to distinguish it from MR.
Have a growling, harsh quality (i.e. get louder and then softer also referred to as a crescendo decrescendo, systolic ejection, or diamond shaped murmur). When the stenosis becomes more severe, the point at which the murmur is loudest occurs later in systole, as it takes longer to generate the higher ventricular pressure required to push blood through the tight orifice.
Are better heard when the patient sits up and exhales.
Are heard in the carotid arteries and over the right clavicle. Radiation to the clavicle can be appreciated by simply resting the diaphragm on the right clavicle. To assess for transmission to the carotids, have the patient hold their breath while you listen over each artery using the diaphragm of your stethescope. Carotid bruits can be confused with the radiating murmur of aortic stenosis. In general, carotid bruits are softer. Also, murmurs associated with aortic pathology should be audible in both carotids and get louder as you move down the vessel, towards the chest. In settings where carotid pathology coexists with aortic stenosis, a loud transmitted murmur associated with a valvular lesion may overwhelm any sound caused by intrinsic carotid disease, masking it completely.
Carotid upstrokes refer to the quantity and timing of blood flow into the carotids from the left ventricle. They can be affected by aortic stenosis and must be assessed whenever you hear a murmur that could be consistent with AS. This is done by placing your fingers on the carotid artery as described above while you simultaneously listen over the chest.
There should be no delay between the onset of the murmur, which marks the beginning of systole, and when you feel the pulsation in the carotid. In the setting of critical aortic stenosis, small amounts of blood will be ejected into the carotid and there will be a lag between when you hear the murmur and feel the impulse. This is referred to as diminished and delayed upstrokes, as opposed to the full and prompt inflow which occurs in the absence of disease. Mild or moderate stenosis does not alter the character of carotid in-flow.
Sub-Aortic stenosis is a relatively rare condition where the obstruction of flow from the left ventricle into the aorta is caused by an in-growth of septal tissue in the region below the aortic valve known as the aortic outflow tract. It causes a crescendo-decrescendo murmur that sounds just like aortic stenosis.
As opposed to AS, however, the murmur is louder along the left lower sternal border and out towards the apex. This makes anatomic sense as the obstruction is located near this region. It also does not radiate loudly to the carotids as the point of obstruction is further from these vessels in comparison with the aortic valve. You may also be able to palpate a bisferiens pulse in the carotid artery.
Furthermore, the murmur will get softer if the ventricle is filled with more blood as filling pushes the abnormal septum away from the opposite wall, decreasing the amount of obstruction. Conversely, it gets louder if filling is decreased. This phenomenon can actually be detected on physical exam and is a useful way of distinguishing between AS and sub-aortic obstruction. Ask the patient to valsalva while you listen. This decreases venous return and makes the murmur louder (and will have the opposite effect on a murmur of AS). Then, again while listening, squat down with the patient. This maneuver increases venous return, causing the murmur to become softer. Standing will cause the opposite to occur. You need to listen for 20 seconds or so after each change in position to really appreciate any difference. Because the degree of obstruction can vary with ventricular filling, sub-aortic stenosis is referred to as a dynamic outflow tract obstruction. In aortic stenosis, the degree of obstruction that exists at any given point in time is fixed.
Murmurs of Mitral Regurgitation (MR):
Sound the same throughout systole.
Generally do not have the harsh quality associated with aortic stenosis. In fact, they sound a bit like the "shshing" noise produced when you pucker your lips and blow through clenched teeth.
Get louder as you move your stethescope towards the axilla.
Will get even louder if you roll the patient onto their left side while keeping your stethescope over the mitral area of the chest wall and listening as they move. This maneuver brings the chamber receiving the regurgitant volume, the left atrium, closer to your stethescope, accentuating the murmur.
Get louder if afterload is suddenly increased, which can be accomplished by having the patient close their hands tightly. MR is also affected by the volume of blood returning to the heart. Squatting increases venous return, causing a louder sound. Standing decreases venous return, thereby diminishing the intensity of the murmur.
Holosystolic
Midsystolic
S1 S2 S1 S1 S2 S1
itral regurgitation co-exist, which can be difficult to sort out on exam. Moving your stethescope back and forth between the mitral and aortic areas will allow for direct comparison, which may help you decide if more then one type of lesion is present or if the quality of the murmur is the same in both locations, changing only in intensity.
2. Diastolic Murmurs
Tend to be softer and therefore much more difficult to hear then those occurring during systole. This makes physiologic sense as diastolic murmurs are not generated by high pressure ventricular contractions. In adults they may represent either aortic regurgitation or mitral stenosis, neither of which is too common. While systolic murmurs are often obvious, you will probably not be able to detect diastolic murmurs on your own until you have had them pointed out by a more experienced examiner.
Aortic Regurgitation (AR):
Is best heard along the left para-sternal border, as this is the direction of the regurgitant flow.
Becomes softer towards the end of diastole (a.k.a. decrescendo).