MRCP revision battle 34.1: The first heart sound

I've just had a whole week off revising.  Very bad from a passing MRCP point of view.  Very good from a remaining sane, keeping friends and staying up-to-date with all the other bits of paper medicine in the UK requires.  Since the exam is now under a month away however I'd better buckle down to it...


MRCP revision battle 34.1: The first heart sound
MRCP revision battle 34.2: The second heart sound
MRCP revision battle 34.3: The third and fourth heart sounds
MRCP revision battle 34.4: Sodium Valproate
MRCP revision battle 34.5: Salicylate overdose
MRCP revision battle 34.6: Haemodialysis in overdose
MRCP revision battle 34.7: Cyanide poisoning
MRCP revision battle 34.8: Phentolamine





MRCP revision battle 34.1: The first heart sound



The first heart sound is made by the closure of the mitral and tricuspid valves.



A loud S1 may be due to:

• mitral stenosis
• hyperdynamic states
• short PR

A soft S1 may be due to:

• long PR
• mitral regurgitation

A    s p l i t  S1 is caused by:

• RBBB
• LBBB
• VT 
• inspiration
• Ebsteins abnormality

A variable S1 is caused by:

• complete heart block
• AF

On to the second heart sound....