Objectives:



PHYSICAL EXAMINATION FOR CARDIAC MURMURS

André N. Sofair, M.D., M.P.H.

WEEK 21

Learning Objectives:

1. To understand the grading of murmurs

2. To understand the most common systolic and diastolic murmurs

3. To discuss the appropriate physical examination maneuvers to better differentiate murmurs

A Historical Note:

Laënnec invented the stethoscope in 1816 when he needed to examine a woman with a large bosom who complained of chest pain. Too shy to put his ear to the woman’s chest, he rolled a paper booklet into a large cylinder, put it onto her chest with his ear at the other end, and heard a murmur. He called the instrument a stethoscope, meaning “breast spy.” (Am J Med 2000; 108: 614-620)

Current “state of the art”:

Recent work has demonstrated that cardiac auscultatory skills of internal medicine and family medicine trainees are poor (They were inaccurate 80% of the time while attempting to identify digitized sounds taken directly from patients.) (JAMA 1997; 278: 717-722). In the hands and ears of cardiologists, however, the examination of the heart is quite precise, with a sensitivity of 70% and a specificity of 98% (American Journal of Cardiology 1996; 77: 1327-1331).

Data on which patients should undergo a physical examination of the heart is limited. A prudent practice would be to examine all patients where a cardiovascular database is desired, those with known or suspected heart disease, and all patients in the preoperative setting, especially where prophylaxis for endocarditis might be indicated.

Data on which murmurs should be further evaluated by echocardiogram are also limited. Benign murmurs tend to be seen in women, those under age 35, and are Grade 2 or softer (JGIM 1994; 9: 479-484). In my opinion, all other murmurs, including all diastolic murmurs and murmurs suggestive of hypertrophic obstructive cardiomyopathy should be evaluated further.

Grading of murmurs:

Grade 1 is a murmur not heard immediately on auscultation. Grade 2 is heard easily but not as loudly as Grade 3. Grade 3 is a very loud murmur. Grade 4 murmurs are associated with a palpable thrill. Grade 5 murmurs are audible with one edge of the stethoscope on the chest and Grade 6 is audible with the stethoscope completely off of the chest (JAMA 1999; 281: 2231-2238).

CASE ONE:

A 65-year-old man is seen with complaints of shortness of breath upon exertion. On examination, his blood pressure is 136/78 and his pulse rate is 90 and regular. He has a normal jugular venous contour and pressure. His lungs are clear. His point of maximal impulse is in the 5th intercostal space, is laterally displaced to the anterior axillary line, and is enlarged. On auscultation, he has a Grade 3 holosystolic murmur best heard at the apex. It does not change during the respiratory cycle and is accentuated by the Valsalva maneuver. Splitting of the second heart sound is normal, and the pulmonic component of the second heart sound is normal in caliber.

Questions:

1. What is your differential diagnosis for this murmur?

The holosystolic quality of the murmur suggests a regurgitant murmur of either the mitral or tricuspid valve. The normal venous contour and pressure, the lack of a pulsatile liver, and the abnormality of the left ventricular impulse all make a left-sided murmur more likely. A VSD or ASD are possible, but the normal quality and splitting of the second heard sound make these unlikely (both are often associated with a prolonged split and a louder P2 component because of increased flow across the pulmonic valve as well as the association with pulmonary hypertension in cases with advanced presentation).

2. What is the importance of the lack of change in the intensity of the murmur during the respiratory cycle?

Right-sided murmurs typically increase with inspiration due to increased venous return to the right side of the heart due to the negative intrathoracic pressure associated with this phase of the respiratory cycle. To detect this, I usually listen where the murmur is just barely audible as I can better appreciate subtle changes in intensity associated with the maneuver. I also listen during quiet breathing, as asking the patient to “take a deep breath” often results in the patient performing a Valsalva maneuver at the same time, which has the undesired effect of decreasing venous return.

The murmur is a left sided murmur suggestive of mitral regurgitation.

3. What is the implication of the augmentation of the murmur with Valsalva maneuver?

The later stages of the Valsalva maneuver (you must wait for stage II of the Valsalva, which begins 10-20 seconds into the maneuver) will decrease venous return, thereby decreasing pre-load to both ventricles (Braunwald, E. Heart Disease, 6th ed. Saunders, Phila. 2001). Only two murmurs augment with a diminished preload. The first is hypertrophic obstructive cardiomyopathy (with diminution in preload, the left ventricular free wall and the hypertrophied septum are more likely to abut one another and create turbulence during systolic ejection of blood and also the anterior leaflet of the mitral valve is more likely to be drawn into the left ventricular outflow tract, causing mitral regurgitation). The second condition is mitral valve prolapse, with or without regurgitation. A diminished preload will decrease cavity size, making the valves relatively more redundant and more likely to balloon back into the atrium without co-apting normally. This murmur is suggestive of mitral valve regurgitation secondary to mitral valve prolapse as was demonstrated by his echocardiogram. To best hear this murmur, have the patient lie down and perform a Valsalva maneuver or ask them to stand. The murmur should be audible over the precordium or at the apex.

4. Are there any other abnormalities of the cardiac examination that you might expect to find with this cardiac condition?

You might expect to hear a midsystolic click (due to the prolapse) which is mobile with different maneuvers. Maneuvers, which diminish pre-load (going from squatting to standing, Valsalva), will accentuate the click and move it closer to S1. This mobility is not found with valvular ejection clicks (usually due to opening of the pulmonic or aortic valve) where the position in the cardiac cycle should remain constant. With late stages of mitral valve prolapse with regurgitation, this click may be absent.

Transient arterial occlusion (inflating two blood pressure cuffs to 20-40 mm above systole in both upper arms) will also accentuate the murmur of mitral regurgitation by augmenting afterload.

CASE TWO:

A 23-year-old woman is in the hospital for Group A streptococcal sepsis related to injection drug use-related septic thrombophlebitis of her axillary vein. Her admission cardiovascular examination and a transthoracic echocardiogram were unremarkable. Although her blood cultures rapidly turned negative, she is noted during her second week of hospitalization to have both a systolic and diastolic murmur (both Grade 3) heard best at the 2nd right intercostal space. Her jugular venous contour and both left and right ventricular point of maximal impulses are normal. Her blood pressure is 140/40 and her pulse volume is hyperdynamic. There are no other stigmata of endocarditis, and her CBC is normal.

5. What is your differential diagnosis for these murmurs?

Their location around the base of the heart suggests either an aortic or a pulmonic murmur. The location over the right side of the chest, the high pulse pressure (greater than 50% of systolic), and the hyperdynamic pulse are more consistent with a left sided lesion.

The combined systolic and diastolic murmurs suggest aortic stenosis/sclerosis and aortic insufficiency. The fact that she had no murmur of aortic stenosis audible on initial examination and the fact that her echocardiogram also failed to reveal this suggests an acquired lesion related to her bacteremia. The hyperdynamic circulatory state associated with aortic insufficiency may produce a systolic flow murmur across a non-stenotic aortic valve (JAMA 1999; 281: 2231-2238). This is a similar phenomenon to the benign flow murmurs associated with pregnancy, hyperthyroidism, anemia, or fever.

The patient’s repeat echocardiogram revealed severe aortic regurgitation with a perivalvular abscess. To best hear this murmur, place the patient in the sitting position, have them exhale (to remove air from the lungs which may muffle the murmur) and listen over the base of the heart.

6. What other manifestations may be associated with this murmur?

As in the case of mitral regurgitation, transient arterial occlusion will augment the murmur of aortic insufficiency. Other associated signs include the deMusset head bobbing sign (forward head-bobbing with each pulse) and pistol shot femoral sounds (heard with the diaphragm over the femoral arteries), both due to increased stroke volume. Quinke’s pulse (pulsations of the nail bed blood vessels visible with light compression of the nail plate) has not been adequately studied.

7. What is the Austin-Flint murmur?

This is a diastolic sound heard over the apex of the heart in the setting of aortic regurgitation, which may mimic the murmur of mitral stenosis. It is heard best with the patient in the left lateral decubitus position and is caused by the regurgitant jet striking the apex or causing the anterior leaflet to close and cause functional but clinically insignificant mitral stenosis. It may be differentiated from mitral stenosis by the absence of the mitral opening snap associated with mitral stenosis and the softening of S1 associated with aortic insufficiency (and not mitral stenosis) due to higher left ventricular preload closing the mitral valve in the former case.

CASE THREE:

An 80-year-old woman is found to have a Grade 2 systolic murmur, which is heard best over the right 2nd intercostal space, radiating to both carotids. It is early peaking, has no diastolic component, and decreases in intensity with Valsalva maneuver. You are able to hear both components of S2 normally, and her carotid pulse volume is normal. Her left ventricular point of maximal impulse is normal, and she has no apical-carotid delay (her apical systolic impulse and her radial pulse occur simultaneously).

8. What is this murmur? Are her findings worrisome?

This murmur suggests either aortic sclerosis or stenosis. The fact that she has an early-peaking murmur, has a normal carotid pulse volume, and that you can hear both components of the second heart sound suggests that her valve is not critically stenotic (usually defined as a valve are of less then 0.8 cm2or a peak transvalvular gradient of more than 50 mm Hg (JAMA 1997; 277: 564-571)). I generally confirm my findings with an echocardiogram unless the murmur appears to be a benign flow murmur (usually a grade 1-2 systolic murmur heard in the left upper sternal border without radiation). An echocardiogram revealed a calcified tricuspid aortic valve with sclerosis but no significant stenosis.

9. What would you have considered had the murmur increased in intensity with a Valsalva maneuver?

As mentioned earlier, only two murmurs should increase in intensity with Valsalva: mitral valve prolapse and hypertrophic cardiomyopathy. The location of this murmur would make mitral valve prolapse very unlikely. Other associated physical findings with hypertrophic obstructive cardiomyopathy include a double carotid impulse (due to the initial systolic outflow of blood, transient outflow obstruction, and second outflow of blood) and a diminution in the murmur with transient arterial occlusion outlined above as slowing the contraction of the ventricle can limit turbulence.

References:

1. Etchells, E, et.al. Does this patient have an abnormal systolic murmur? JAMA.

1997; 277: 564-571.

2. Choudhry, NT, et.al. Does this patient have aortic regurgitation? JAMA. 1999;

281: 2231-2238

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