Murmurs Flashcards
S1 and S2 heart sounds
first heart sound (S1) is caused by the closing of the atrioventricular valves (the tricuspid and mitral valves) at the start of the systolic contraction of the ventricles. “LUB”
the second heart sound (S2) is caused by the closing of the semilunar valves (the pulmonary and aortic valves) once the systolic contraction is complete “DUB”
what is the S3 heart sound?
Athird heart sound (S3) is heard roughly 0.1 seconds after the second heart sound. I think of it as rapid ventricular filling causing thechordae tendineae to pull to their full length and twang like a guitar string.
This can be normal in young (15-40 years) healthy people because the heart functions so well that the ventricles easily allow rapid filling.
In older patients it can indicated heart failure, as theventricles andchordae are stiff and weak so they reach their limit much faster than normal. Picture this like tight hamstrings in an old de-conditioned patient sharply tightening as they start to bend over.
what is the S4 heart sound?
Afourth heart sound(S4) is heard directly beforeS1. This is always abnormal and relatively rare to hear.
It indicates a stiff or hypertrophic ventricle and is caused by turbulent flow from an atria contracting against a non-compliant ventricle.
How to listen for murmurs?
Auscultate with thebellof your stethoscope to better hearlow pitchedsounds and thediaphragmto listen tohigh pitchedsounds. To remember this think of a childshigh-pitchedscreaming from theirdiaphragmvs a churchbellgiving adeep“bong”.
Listen over the4 valve areasin turn for murmurs:
- Pulmonary 2nd I.C.S left sternal border
- Aortic: 2nd I.C.S right sternal border
- Tricuspid: 5th I.C.S left sternal border
- Mitral: 5th I.C.S mid clavicular line (apex area)
Listen to “Erb’s point”. This is in thethirdintercostal spaceon theleft sternal borderand is the best area for listening to heart sounds (S1andS2).
Special manoeuvrescan be used to emphasise certain murmurs:
- Patient on their left hand side (mitral stenosis)
- Patient sat up, learning forward and holding exhalation (aortic regurgitation)
SCRIPT mneumonic for assessing a murmur
- Site: where is the murmur loudest?
- Character: soft / blowing / crescendo (getting louder) / decrescendo (getting quieter) / crescendo-decrescendo (louder then quieter)
-Radiation: can you hear the murmur over the carotids (AS) or left axilla (MR)? - Intensity: what grade is the murmur?
- Pitch: is it high pitched or low and grumbling? Pitch indicates velocity.
- Timing: is it systolic or diastolic?
Murmur grading?
Grading a murmur is quite subjective but is helpful is assessing the severity of the defect and will make you sound clever. If in doubt it is probably grade 2 or 3.
- Difficult to hear
- Quiet
- Easy to hear
- Easy to hear with a palpable thrill
- Can hear with stethoscope barely touching chest
- Can hear with stethoscope off the chest
Hypertrophy vs Dilation?
Valvular heart disease can causehypertrophy(thickening both outwards and into the chamber) ordilatation(thinning and expanding – think of blowing up a balloon) of themyocardiumin different heart areas.
When pushing against a stenotic valve the muscle has to try harder resulting in hypertrophy:
- Mitral stenosiscausesleft atrial hypertrophy.
- Aortic stenosiscausesleft ventricular hypertrophy.
When a leaky valve allows blood to flow back into a chamber it stretches the muscle resulting in dilatation:
- Mitral regurgitationcausesleft atrial dilatation.
- Aortic regurgitationcausesleft ventricular dilatation.
What is mitral stenosis?
This is a narrowmitral valvemaking it difficult for the left atrium to push blood through to the ventricle.
It causes amid-diastolic,low pitched“rumbling” murmur due to a low velocity of blood flow. There will be a loud S1 due to thick valves requiring a large systolic force to shut, then shutting suddenly. You can palpate a tapping apex beat due to loud S1.
Mitral stenosis is caused by:
- Rheumatic Heart Disease
- Infective Endocarditis
Mitral stenosis of associated with what signs?
Malar flush. This is due to back-pressure of blood into the pulmonary system causing a rise in CO2 and vasodilation.
Atrial fibrillation. This is caused by the left atrium struggling to push blood through the stenotic valve causing strain, electrical disruption and resulting fibrillation.
What is mitral regurgitation?
Mitral regurgitation is when an incompetent mitral valve allows blood to lead back through during systolic contraction of the left ventricle. It results incongestive cardiac failurebecause the leaking valve causes a reduced ejection fraction and a backlog of blood that is waiting to be pumped through the left side of the heart.
It causes apan-systolic,high pitched“whistling” murmur due to high velocity blood flow through the leaky valve. The murmur radiates to left axilla. You may hear a third heart sound.
Causes of mitral regurgitation?
- Idiopathic weakening of the valve with age
- Ischaemic heart disease
- Infective Endocarditis
- Rheumatic Heart Disease
- Connective tissue disorders such asEhlers Danlos syndromeorMarfan syndrome
What is aortic stenosis?
Aortic stenosis is the most common valve disease you will encounter. It causes anejection-systolic,high pitchedmurmur (high velocity of systole). This has acrescendo-decrescendocharacter due to the speed of blood flow across the value during the different periods ofsystole. Flow during systole is slowest at the very start and end and fastest in the middle.
Other signs of aortic stenosis?
- The murmur radiates to thecarotidsas the turbulence continues up into the neck
- Slow rising pulseandnarrow pulse pressure
- Patients may complain ofexertional syncope(light headedness and fainting when exercising) due to difficulty maintaining good flow of blood to the brain
Causes of aortic stenosis?
- Idiopathic age related calcification
- Rheumatic Heart Disease
