Normal S1 Sounds And Variations

Front 1

Accentuated S1

Back 1

louder than S2
occurs when mitral valve is wide open and closes quickly
ex: blood velocity increases with fever, anemia, hyperthyroidsim
mitral stenosis where leaflet are still mobile but increased ventricular pressure is needed to close valve

Front 2

Diminished S1

Back 2

softer than S2
occurs when mitral valve not fully open during ventricular contraction and valve closing
ex: delayed conduction from atria to ventricles in 1st degree heart block (allows mitral valve to close b4 ventricular contraction closes it)
Mitral insufficiency w/ extreme calcification of valve limits mobility
Delayed or diminished ventricular contraction due to forceful atrial contraction into noncompliant ventricle (severe pulmonary or systemic hypertension)

Front 3

Split S1

Back 3

split sound
occurs when RV and LV contract at different times (asynchronous ventricular contraction)
ex: Conduction delaying cardiac impulse to one of ventricles (bundle branch block)
Ventricular ectopy in which impulse starts in one ventricle, contracting it first, then spreading to 2nd ventricle

Front 4

Varying S1

Back 4

occurs when mitral valve is in different positions when contraction occurs
ex: rhythms in which the atria and ventricles are beating independently of each other
Totally irregular rhythm such a Afib

Front 5

Accentuated S2

Back 5

louder than S1
occurs in conditions in which aortic or pulmonic valve has a higher closing pressure
ex: increased pressure in the aorta from exercise, excitement, or systemic hypertension (a booming S2 is heard w/ systemic hypertension)
Increased pressure in pulmonic vasculature, which may occur with mitral stenosis or congestive heart failure
calcification of SL valve in which valve is still mobile (pulmonic or aortic stenosis)

Front 6

Diminished S2

Back 6

S2 is softer than S1
occurs in conditions in which aortic or pulmonic valves have decreased mobility
ex: Decreased systemic blood pressure (weakens the valves, as in shock)
Aortic or pulmonic stenosis in which the valves are thickened and calcified, with decreased mobility

Front 7

Normal Physiologic Split S2

Back 7

normal split S2
heard over 2nd and 3rd ICS
best heard during inspiration and disappears during expiration
splitting that doesn't disappear during expiration suggest heart disease

Front 8

Wide Split S2

Back 8

increase in usual splitting that persists throughout entire respiratory cycle and widens on expiration
occurs when there is a delayed electrical activation of the RV
ex: right bundles block, delays pulmonic valve closing

Front 9

Fixed Split S2

Back 9

wide splitting
doesn't vary with respiration
occurs when delayed closure of one of the valves
ex: atrial septal defect and RV failure, delays pulmonic valve closing

Front 10

Reversed Split S2

Back 10

Split S2 that appears on expiration and disappears on inspiration
also called paradoxical split
occurs when closure of aortic valve is abnormally delayed, causing A2 to follow P2, in expiration
ex: left bundle block

Front 11

Accentuated A2

Back 11

loud over the right 2nd ICS
occurs w/ increased pressure in systemic hypertension and aortic root dilation because of the closer position of the aortic valve to chest wall

Front 12

Diminished A2

Back 12

soft or absent over the right 2nd ICS
occurs with immobility of the aortic valve in calcific aortic stenosis

Front 13

Accentuated P2

Back 13

louder than or equal to and A2
occurs with pulmonary hypertension, dilated pulmonary artery, and atrial septal deftect
wide split S2 heard even at apex indicates accentuated P2

Front 14

Diminished P2

Back 14

soft or absent P2
occurs with increased anteroposterior diameter of the chest (barrel chest)
associated with aging, pulmonic stenosis, or COPD