Heart Murmurs

Question 1

Murmur vs Bruit

Answer 1

• When normal laminar blood flow within the heart is disrupted, an audible sound is created by turbulent blood flow.
• Outside of the heart audible turbulence is referred to as a bruit, while inside the heart it is called a murmur

Question 2

Causes of murmurs

Answer 2

1. Blood forced through tight area (stenosis): worse= louder except in HF (adequate pressures for murmurs not achieved so lessen/ disappear)
2. Valvular insufficiency (backflow through incompetent valve creating turbulence when meets forward blood flow)
3. Blood forced through congenital abnormality from chamber to another (ASD/ VSD)
4. Increased flow of blood through normal valve in high output states (anaemia, thyrotoxicosis, sepsis)

Question 3

What are the categories for describing heart murmurs?

Answer 3

• Timing
• Grading
• Shape
• Pitch
• Location
• Radiation

Question 4

Timing of murmurs

Answer 4

-Systolic (between S1 and S2): aortic/ pulmonary stenosis vs mitral and tricuspid regurgitation
=mid/holo vs pan/ late
-Diastolic (between S2 and S1): a/p regurgitation vs m/t stenosis
=early/late
-Continuous: patent ductus arteriosus/ combination murmurs

Question 5

Systolic murmurs

Answer 5

1. Midsystolic (just after S1 and terminates just before S2)
   - AS
   - Pulmonary stenosis
   - ASD
   - Hypertrophic obstructive cardiomyopathy
2. Holosystolic (begins with or immediately after S1 and extends up to S2 so difficult to hear)
   - MR
   - Tricuspid regurgitation
   - VSD
3. Late (begins significantly after S1)
   - Mitral valve prolapse

Question 6

Diastolic murmurs

Answer 6

1. Early
   - AR
   - Pulmonary regurgitation
   - Austin-Flint
2. Mid/late
   - MS
   - Tricuspid S

Question 7

Grading systolic murmurs

Answer 7

1. Barely audible
2. Audible but soft
3. Easily audible
4. Easily audible and associated with a thrill
5. Easily audible, associated with a thrill, and still heard with a stethoscope only lightly on the chest
6. Easily audible, associated with a thrill, and still heard with the stethoscope off the chest

Question 8

Grading diastolic murmurs

Answer 8

1. Barely audible
2. Audible but soft
3. Easily audible
4. Loud

-Intensity determined by volume/ velocity of blood through defect and distance between stethoscope and lesion

Question 9

Shape of murmur

Answer 9

-Describes the change of intensity throughout the cardiac cycle
=crescendo
=decrescendo
=crescendo-decrescendo
=uniform

Question 10

Pitch of murmur

Answer 10

-High pitched= large pressure gradient across the pathologic lesion (diaphragm)
-Low pitched= pressure gradient is low (bell)
=AS high pitched since there is usually a large pressure gradient between the LV and the aorta, may radiate to apex
=MS low pitched since there is a lower pressure gradient between the LA and the LV during diastole.

Question 11

Location of murmur

Answer 11

• A = aortic valve post (right upper sternal border or RUSB)
• P = pulmonic valve post (left upper sternal border or LUSB)
• T = tricuspid valve post (left lower sternal border or LLSB)
• M = mitral valve post (apex)
• E = “Erb’s point”

Question 12

Radiation of murmur

Answer 12

• AS frequently radiates to the carotid arteries
• MR radiates to the left axillary region.
• It is often difficult to distinguish if one murmur is radiating to multiple sites or if there are multiple murmurs present from many different causes.
• Dynamic auscultation and echocardiography is helpful in determining the exact lesion present.

Question 13

Aortic Stenosis murmur

Answer 13

-High pitched
-Crescendo-decrescendo (diamond shaped)
-Aortic listening post and radiates to carotid, can also radiate to apex (Gallavardin dissociation)
=Dynamic auscultation/ echo to determine coexisting MR
-Worsens= LV failure= ejection fraction declines= insufficient force for turbulent flow= decreased intensity
-Worsens= longer for blood to eject through valve= later in systole
-Paradoxically split S2 as A valve heavily calcified, intensity of S2 declines

Question 14

Pulmonary stenosis murmur

Answer 14

• Midsystolic high-pitched crescendo-decrescendo
• Pulmonary listening post and radiates slightly towards the neck (nor as widely as AS)
• Mild= early, severe= later
• Increasing intensity during inspiration due to increased venous return to R heart= greater flow across P valve
• Severe PS= decreased mobility of the pulmonic valve leaflets= softer P2
• Worsens= delayed closure (longer to eject blood)= widely split S2 heart sound that still exhibits inspiratory delay.

Question 15

ASD murmur

Answer 15

-Increased flow through pulmonic valve= similar to PS
=Intensity of S2 unchanged/ accentuated if pulmonary hypertension develops
=S2 fixed-split (not widened in PS)
=Murmur not increased intensity with inspiration

Question 16

Hypertrophic obstructive cardiomyopathy (HOCM) murmur

Answer 16

-High pitched
-Crescendo- decrescendo
-Mid systolic
-Left lower sternal border
-Does not radiate to carotids
-Distinguish from AS through dynamic auscultation
=HOCM more intense after standing and less intense after rapid squatting compared to AS

Question 17

MR murmur

Answer 17

• High-pitched, “blowing” holosystolic murmur best heard at the apex
• Radiation depends on nature of disease but usually axilla
• Intensity of murmur does not increase with inspiration

Question 18

Tricuspid regurgitation murmur

Answer 18

• High pitched, holosystolic murmur however it is best heard at the left lower sternal border and it radiates to the right lower sternal border
• Intensity increases significantly with inspiration (Carvallo’s sign)

Question 19

VSD murmur

Answer 19

• Blood abnormally flows from the LV (high pressure) to the RV (low pressure) creating turbulent blood flow and a holosystolic murmur heard best at “Erb’s point”.
• The smaller the ventricular septal defect, the louder the murmur.

Question 20

Mitral valve prolapse murmur

Answer 20

-Mid-systolic click usually followed by a uniform, high-pitched murmur.
-The murmur is actually due to mitral regurgitation that accompanies the mitral valve prolapse, thus it is heard best at the cardiac apex.
-Mitral valve prolapse responds to dynamic auscultation.
=Extends with sudden standing and decreases with sudden squatting

Question 21

AR murmur

Answer 21

• Soft, high-pitched, early diastolic decrescendo murmur usually heard best at the 3rd intercostal space on the left (Erb’s point)/ right upper sternal border if due to aortic root disease at end expiration with the patient sitting up and leaning forward.
• Worsens= pressure between the left ventricle and the aorta equalize much faster, thus the murmur becomes significantly shorter
• Systolic ejection murmur may be present in people with severe aortic regurgitation at the right upper sternal border simply due to the large stroke volume passing through the aortic valve with each systolic contraction of the LV

Question 22

Austin Flint murmur

Answer 22

In people with aortic regurgitation, an early diastolic rumble may also be heard at the apex due to the regurgitant jet striking the anterior leaflet of the mitral valve causing it to vibrate.

Question 23

Pulmonic regurgitation murmur

Answer 23

• Often indistinguishable from that of AR.
• soft, high-pitched, early diastolic decrescendo murmur heard best at the pulmonic listening post (LUSB).
• Increases in intensity during inspiration, unlike that of AR.
• Graham-Steell murmur

Question 24

MS murmur

Answer 24

• Uniquely shaped, low-pitched diastolic murmur best heard at the cardiac apex.
• Opening of the mitral valve= “opening snap” due to the high left atrial pressures, which is immediately followed by a decrescendo murmur as blood flows passively from the left atrium to the left ventricle through the stenosed mitral valve creating turbulence.
• Immediately before the S1 sound, active left ventricular filling occurs when the left atrium contracts and forces more blood through the stenosed mitral valve creating a late diastolic crescendo murmur.
• In the presence of AF, the active left ventricular filling phase does not take place and the latter part of the MS murmur disappears.
• Worsens= left atrial pressure increases forcing the mitral valve open earlier in diastole= opening snap occurs earlier as does the initial decrescendo part of the murmur.
• The opening snap and murmur of mitral stenosis also respond to dynamic auscultation.

Question 25

Patent ductus arteriosus murmur

Answer 25

- Continuous throughout systole and diastole - Often S2 difficult to detect - Begins just after S1 and crescendos peaking at S2 and decrescendos to S1

Question 26

What is dynamic auscultation?

Answer 26

Manoeuvres to alter hemodynamic parameters during cardiac auscultation in order to diagnose the aetiology of a heart sound or murmur

Question 27

Valsalva manoeuvre

Answer 27

- Patient “bear down” like they are going to have a bowel movement and exhaling forcefully with the airway closed. - The hemodynamic changes that occur are complex, however the ultimate result is a decrease in left ventricular preload. - AS vs HOCM/ bring for the murmur of HOCM. =AS will soften or not change while the murmur of HOCM becomes quite loud with Valsalva. - If the Valsalva manoeuvre fails to reduce the left ventricular pressure in the setting of diastolic heart failure, then grade IV diastolic dysfunction is said to be present which indicates a poor prognosis

Question 28

Squatting from standing position

Answer 28

- Squatting forces the blood volume that was stored in the legs to return to the heart increasing preload and thus increasing left ventricular filling - Decrease HOCM as the increased left ventricular volume helps displace the hypertrophied interventricular septum causing less outflow tract obstruction. - Also causes click of mitral valve prolapse to move later in systole

Question 29

Standing from a squatting position

Answer 29

- Causes blood to move from the central body to the legs resulting in less blood returning to the heart decreasing left ventricular preload - Increase HOCM and decrease AS. - Click of mitral valve prolapse to move earlier in systole

Question 30

Leg raising

Answer 30

- Raising the legs high in a patient lying supine. =Blood that was pooled in the legs returning to the heart increase left ventricular filling and preload - Decrease HOCM as the increased left ventricular volume helps displace the hypertrophied interventricular septum causing less outflow tract obstruction. - Click of mitral valve prolapse to move later in systole.

Question 31

Isometric handgrip exercise

Answer 31

-Patient squeeze hand repetitively =Increased blood pressure (similar to exercise) and thus increased afterload. -Elderly= transient arterial occlusion can be used instead. -Increase the intensity of left-sided regurgitant murmurs including MR and AR. -No effect on the murmur of AS which helps distinguish the presence of coexistent MR from that of the Gallavardin phenomenon.

Question 32

Transient arterial occlusion

Answer 32

-Blood pressure cuff on both arms and inflating it to 20 to 40 mmHg above the systolic blood pressure for 20 seconds. =Increased afterload. -Increase the intensity of left-sided regurgitant murmurs including MR and AR and is especially useful in elderly individuals who are not able to perform adequate handgrip exercises.

Question 33

Amyl nitrate inhalation

Answer 33

-Decreases left ventricular afterload by dilating the peripheral arteries. -Decrease MR. =When the afterload is decreased, there is less resistance to blood flow from the left ventricle through the aortic valve and thus less blood regurgitates through the mitral valve, decreasing the intensity of the murmur. -Reduce afterload for diagnostic purposes in the cardiac catheterization laboratory (to invoke a LV outflow tract gradient in HOCM) or as a diagnostic tool during cardiac physical examination. -Not commonly used any longer.