Heart Murmurs Flashcards
Murmur vs Bruit
- 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
Causes of murmurs
- Blood forced through tight area (stenosis): worse= louder except in HF (adequate pressures for murmurs not achieved so lessen/ disappear)
- Valvular insufficiency (backflow through incompetent valve creating turbulence when meets forward blood flow)
- Blood forced through congenital abnormality from chamber to another (ASD/ VSD)
- Increased flow of blood through normal valve in high output states (anaemia, thyrotoxicosis, sepsis)
What are the categories for describing heart murmurs?
- Timing
- Grading
- Shape
- Pitch
- Location
- Radiation
Timing of murmurs
-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
Systolic murmurs
- Midsystolic (just after S1 and terminates just before S2)
- AS
- Pulmonary stenosis
- ASD
- Hypertrophic obstructive cardiomyopathy - Holosystolic (begins with or immediately after S1 and extends up to S2 so difficult to hear)
- MR
- Tricuspid regurgitation
- VSD - Late (begins significantly after S1)
- Mitral valve prolapse
Diastolic murmurs
- Early
- AR
- Pulmonary regurgitation
- Austin-Flint - Mid/late
- MS
- Tricuspid S
Grading systolic murmurs
- Barely audible
- Audible but soft
- Easily audible
- Easily audible and associated with a thrill
- Easily audible, associated with a thrill, and still heard with a stethoscope only lightly on the chest
- Easily audible, associated with a thrill, and still heard with the stethoscope off the chest
Grading diastolic murmurs
- Barely audible
- Audible but soft
- Easily audible
- Loud
-Intensity determined by volume/ velocity of blood through defect and distance between stethoscope and lesion
Shape of murmur
-Describes the change of intensity throughout the cardiac cycle =crescendo =decrescendo =crescendo-decrescendo =uniform
Pitch of murmur
-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.
Location of murmur
- 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”
Radiation of murmur
- 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.
Aortic Stenosis murmur
-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
Pulmonary stenosis murmur
- 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.
ASD murmur
-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