Basics of Heart Sounds

What are the 2 main heart sounds that can be heard during auscultation?

• S1 = lub = corresponds to the closing of the mitral and tricuspid valves during systole

  • during systole = ventricular pressure rises, leading to opening of aortic and pulmonary valves + closing of mitral and tricuspid valves

• S2 = dub = corresponds to the closing of aortic and pulmonary valves at beginning of diastole

What can S2 be subdivided into?

• S2 may be subdivided into aortic A2 and pulmonary P2 sounds as aortic valve closes slightly before pulmonary valve

• the splitting between A2 and P2 can be exaggerated by inspiration in particularly young individuals

When can be pulse be felt?

• during systole between S1 and S2 heart sounds

• important for differentiating between systolic ad diastolic murmurs

What causes ejection systolic click?

• Aortic stenosis

• Pulmonary stenosis

Just after S1

What causes mid-systolic click?

• mitral valve prolapse

In middle of systole

What causes an opening snap?

• Mitral stenosis

• Tricuspid stenosis

Just after P2

What are S3 and S4 heart sounds?

• arise after S2

• S3 = after ventricular filling = normal in people 40 and under

• S4 = when atria contract against a stiff ventricle (e.g. ventricular hypertrophy)

What ate the pathological causes of S3?

• Ischaemic heart disease

• Dilated cardiomyopathy

• Hypertrophic cardiomyopathy

• Mitral regurgitation

Just after P2

What are the pathological causes of S4?

• Hypertension

• Pulmonary hypertension

• Aortic stenosis

• Hypertrophic cardiomyopathy

Just before S1

What is a tumour plop?

A rare diastolic heart sound classically associated with the movement of the tumour in atrial myxomas

What can the loudness of heart sounds be altered?

changes in the force of valve closure

What are the causes of a loud S1 heart sound?

• Mitral stenosis

• Atrial fibrillation

What is a cause of a loud A2 heart sound?

Systemic hypertension

What are the causes of a loud P2 heart sound?

• Pulmonary hypertension

• Atrial septal defect

What is a wide-splitting S2 heart sound?

Splitting increases with inspiration

What are the causes of a wide-splitting S2 heart sound?

• Right bundle branch block

• Pulmonary stenosis

• Mitral regurgitation

• Ventricular septal defect

What is a fixed splitting S2 heart sound?

splitting not affected by breathing

What is a cause of a fixed splitting S2 heart sound?

• Atrial septal defect

What is a reversed splitting S2 heart sound?

Splitting decreases with inspiration (so much that it can lead to P2 arising before A2)

What are the causes of a reversed splitting S2 heart sound?

• Left bundle branch block

• Aortic stenosis

• Coarctation of the aorta

• Patent ductus arteriosus