S2 is normally split because the aortic valve (A2) closes before the pulmonary valve (P2). The closing pressure (the diastolic arterial pressure) on the left is 80 mmHg as compared to only 10 mmHg on the right. This higher closing pressure leads to earlier closure of the aortic valve.

Why does physiologic splitting occur?

Physiological S2 splitting is thought to occur due to changes in the timing of the closure of the pulmonary and aortic valves during the respiratory cycle.

Why is S2 split in ASD?

The most characteristic feature of an atrial septal defect is the fixed split S2. As mentioned in the murmur overview, a split S2 is caused physiologically during inspiration because the increase in venous return overloads the right ventricle and delays the closure of the pulmonary valve.

What is responsible for the second Auscultated heart sound?

The most tenable to date suggests that closure of the aortic and pulmonic valves initiates the series of events that produces the second heart sound. The main audible components, however, result from vibrations of the cardiac structures after valve closure.

What is physiological splitting?

Physiologic Split S2 This happens during inspiration when increased venous return to the right side of the heart delays the closure of the pulmonic valve (major effect), and decreased return to the left side of the heart hastens the closure of the aortic valve (minor effect), thereby further separating A2 and P2.

What is paradoxical splitting of S2?

A paradoxical split S2 heart sound occurs when the splitting is heard during expiration and disappears during inspiration, the opposite of the physiologic split S2.

Is a split S2 a murmur?

Valvular Heart Disease Physical examination may reveal a prominent jugular A wave, an RV heave, and a thrill on the left sternal border. Auscultation shows a normal S₁, a single or split S ₂ with a weakened P₂, and a systolic ejection murmur that is best heard on the second intercostal space at the left sternal border.

When would you expect to hear a split S2?

Splitting of the S2 can happen during inspiration. It is heard when the aortic valve closes earlier than the pulmonic valve. Instead of it sounding like “dub” it sounds like “T-Dub”. You will hear this sound at the apex in the left lateral position.

Why does the second heart sound occur after the T wave?

The second heart sound, called S2, makes a “dub” sound caused by the closure of the semilunar (aortic and pulmonary) valves following ventricular systole. S2 is split because aortic valve closure occurs before pulmonary valve closure.

What is the second heart sound called?

The second heart sound, or S₂, forms the “dub” of “lub-dub” and is composed of components A₂ (aortic valve closure) and P₂ (pulmonary valve closure).

What action causes the second heart sound heard through a stethoscope?

what action causes the second heart sound heard through a stethoscope? closing of the semilunar and blood hitting against the valves.

What does a split S1 heart sound mean?

A split S1 sound is common in the setting of a right bundle branch block or ventricular tachycardia/premature ventricular contractions, or PVCs, with a right bundle branch block morphology. A RBBB causes the electrical impulse to reach the left ventricle before the right ventricle.

Why is the second heart sound louder than the first?

The second heart sound (S₂) (see Figure 1-9) is produced by passive closure of the aortic and pulmonic valves. It is short, high pitched, and sharp. It is loudest over the aortic and pulmonic areas. A split S₂ (see Figure 1-9) is due to closure of the pulmonic valve after the aortic valve.

What does a loud second heart sound mean?

Loud second heart sounds can be loud A2 or a loud P2. loud A2 occurs in systemic hypertension where there is a dilated proximal aorta. a loud P2 is heard in pulmonary hypertension. a loud P2 occurs in an atrial septal defect without pulmonary hypertension.