S3 and S4 Heart Sounds

Mid-diastolic sounds are,either normal or abnormal S3 sounds, and most late diastolic or presystolic sounds are S4 sounds.

Low frequency sounds heard with the bell of stethoscope

LV S3, S4 heard over the left ventricular apex with the patient in the left lateral decubitus position

RV S3, S4 heard over the lower left sternal edge, occasionally subxiphoid with the patient supine becoming more prominent during inspiration.

A left sided S3 AND S4 is augmented post-tussively and with sustained handgrip exercise.

S3 heart sound Ventricular gallop sound

Heard during the rapid ventricular filling phase

Physiological: Children and young adults

A normal S3 sometimes persists beyond the age of 40, especially in women. Often associated with a thin, asthenic body habitus

Decreased prevalence with increasing age

Triple rhythm-S1+S2+S3 OR S4

Quadruple rhythm-S1+S2+S3+S4

Pathological S3

-Ventricular dysfunction- poor systolic function, increased end-diastolic and end-systolic volume, decreased EF, and high filling pressures

1. Idiopathic DCM2. IHD3. Valvular heard disease- Chronic MR, Chronic AR4. Congenital heart disease-VSD, PDA, ASD with

high flow across tricuspid valve5. Systemic and pulmonary hypertension

-Excessive rapid early diastolic ventricular filling

1. HYPERKINETIC STATES- Anemia, Thyrotoxicosis, AV fistula

2. AV valve incompetence- Left-to-right shunts

-Restrictive myocardial or pericardial disease

S4 heart sound Atrial gallop sound – atrial diastolic gallop or the presystolic gallop

Follows the onset of P wave on ECG by approximately 70 ms

S4 coincides with a waves of the atrial pressure pulse, atrial systole and with the apical impulse.

Sometimes heard in healthy old adults without clinical evidence of heart disease, particularly after exercise

Pathological S4

1. Severe LVH- systemic hypertension, valvular AS (peak transvalvular gradient more than 70 mmHg), hypertrophic cardiomyopathy

2. IHD- acute episode of angina and in the early phases of transmural MI

3. LV aneurysm (with S3)4. Idiopathic or ischemic cardiomyopathy (with S3)5. Acute AV valve regurgitation 6. Heart block- First degree, 2:1, Complete

A loud S4 that is also usually palpable is a frequent finding in acute and severe MR or AR. It is almost always associated with an increased LV end-diastolic pressure (>15 mmHg).

PERICARDIAL KNOCKVentricular filling is confined to early diastole in constrictive pericarditis and terminates with a sharp S3. This is termed pericardial knock. Its timing is earlier than a normal S3 and typically occurs 0.1 to 0.12 seconds after S2.

Dr Nikita J.Mehra

II year MD General Medicine Post Graduate