Lena Torres
The second heart sound (S2) is produced by the closure of the aortic and pulmonic valves, with the aortic valve (A2) closing before the pulmonic valve (P2). S2 heart sounds are best heard when patients are semi-recumbent and in quiet inspiration. A2 is louder than P2 and can be heard all over the chest, while P2 is usually only heard at the left upper sternal border. A paradoxical split S2 occurs when the splitting is heard during expiration and disappears during inspiration, opposite to the normal physiologic split S2. Diagnoses such as pulmonary hypertension, severe aortic stenosis, and atrial septal defects can be suspected or confirmed by listening to second heart sounds.
| Characteristics | Values |
|---|---|
| What is S2? | The second heart sound produced by the closure of the aortic and pulmonic valves. |
| A2 | The sound produced by the closure of the aortic valve. |
| P2 | The sound produced by the closure of the pulmonic valve. |
| A2 and P2 closure | A2 closes before P2. |
| A2 and P2 intensity | A2 is normally louder than P2. |
| A2 listening position | A2 is heard widely all over the chest and is loudest at the right upper sternal border. |
| P2 listening position | P2 is usually heard at the left upper sternal border. |
| S2 splitting | S2 is normally split in about 90% of people. |
| S2 types | Persistent (widened) splitting, fixed splitting, paradoxical (reversed) splitting, absence of splitting. |
| Paradoxical splitting | P2 is heard before A2. |
| Causes of paradoxical splitting | Any setting that delays the closure of the aortic valve, including severe aortic stenosis, hypertrophic obstructive cardiomyopathy, or in the presence of a left bundle branch block. |
| Persistent (widened) splitting | Both A2 and P2 are audible during the entire respiratory cycle, and the splitting becomes greater with inspiration and less prominent with expiration. |
| Fixed splitting | A fixed delay in PV closure due to altered cardiac hemodynamics. |
Explore related products
What You'll Learn
- S2 heart sounds are heard during the phase of the cardiac cycle known as isovolumetric relaxation
- Aortic valve closure (A2) happens first
- Pulmonic valve closure (P2) happens second
- S2 heart sounds are best heard when patients are semi-recumbent
- Diagnoses like pulmonary hypertension can be suspected with close attention to second heart sounds
S2 heart sounds are heard during the phase of the cardiac cycle known as isovolumetric relaxation
The second heart sound (S2) is produced by the closure of the aortic and pulmonic valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2. A2 is usually much louder than P2 due to higher pressures in the left side of the heart. A2 can be heard widely across the chest, while P2 is usually only heard at the left upper sternal border.
The S2 heart sound can exhibit different types of splitting, including persistent (widened) splitting, fixed splitting, and paradoxical (reversed) splitting. Persistent splitting occurs when both A2 and P2 are audible during the entire respiratory cycle, with the splitting becoming greater during inspiration due to increased venous return. Fixed splitting is caused by altered cardiac hemodynamics, resulting in a fixed delay in pulmonic valve closure. Paradoxical splitting occurs when the splitting is heard during expiration and disappears during inspiration, opposite to the physiologic split.
During the cardiac cycle, the heart undergoes a period of isovolumetric relaxation, also known as isovolumic relaxation time (IVRT). This interval occurs between the aortic component of the second heart sound (closure of the aortic valve) and the onset of filling by the opening of the mitral valve. IVRT is an indicator of diastolic dysfunction and can be measured using Doppler echocardiography and M-mode sonography or phonocardiogram and transmitral Doppler.
Therefore, S2 heart sounds are heard during the phase of the cardiac cycle known as isovolumetric relaxation. Specifically, S2 corresponds to the closure of the aortic and pulmonic valves, with A2 occurring just before P2. The subtle changes in the S2 heart sound, including the presence and type of splitting, can provide valuable clues about the heart's function and potential abnormalities.
Unveiling the World of Sounds
You may want to see also
Explore related products
Aortic valve closure (A2) happens first
The second heart sound, or S2, is produced by the closure of the aortic and pulmonic semilunar valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2. The aortic valve typically closes before the pulmonic valve, meaning A2 happens first.
A2 is normally much louder than P2 and can be heard widely all over the chest. This is due to the higher pressures in the left side of the heart. A2 is the main component of S2. During auscultation, A2 can be heard at the mitral area, while P2 is usually only audible at the pulmonic region (left parasternal, intercostal space 2).
The splitting between A2 and P2 can be exaggerated by inspiration, particularly in young individuals. This is known as a physiologic split, and it occurs when the A2 sound precedes P2 by a large enough distance to allow both sounds to be heard separately. During inspiration, increased venous return to the right side of the heart delays the closure of the pulmonic valve, while decreased return to the left side of the heart hastens the closure of the aortic valve. This further separates A2 and P2, making them more distinguishable.
In contrast, a paradoxical split of S2 occurs when the splitting is heard during expiration and disappears during inspiration, which is the opposite of the physiologic split. This can happen in settings that delay the closure of the aortic valve, such as severe aortic stenosis or hypertrophic obstructive cardiomyopathy, or in the presence of a left bundle branch block.
The "Why Are You Gay?" Sound Clip Explained
You may want to see also
Explore related products
Pulmonic valve closure (P2) happens second
The second heart sound (S2) is produced by the closure of the aortic and pulmonic valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2. The aortic valve (A2) closes before the pulmonic valve (P2), making P2 the second of the two sounds.
The A2 sound is normally much louder than the P2 due to higher pressures in the left side of the heart. A2 radiates to all cardiac listening posts and is loudest at the right upper sternal border. On the other hand, P2 is usually only heard at the left upper sternal border as it is softer than A2. The combination of these two sounds makes up S2.
A physiologic split S2 occurs when the A2 sound precedes P2 by a significant enough distance to allow both sounds to be heard separately. This happens during inspiration when increased venous return to the right side of the heart delays the closure of the pulmonic valve. At the same time, decreased return to the left side of the heart hastens the closure of the aortic valve, further separating A2 and P2. During expiration, the distance narrows, and the split S2 is no longer audible.
The venous return to the right ventricle increases during inspiration due to negative intrathoracic pressure, which delays P2 even more. As a result, it is normal for the split of the second heart sound to widen during inspiration and narrow during expiration. This phenomenon is more noticeable with slower heart rates.
Turn Off Charging Case Sounds: Quick Guide
You may want to see also
Explore related products
S2 heart sounds are best heard when patients are semi-recumbent
The second heart sound (S2) is produced by the closure of the aortic and pulmonic valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2. The A2 sound is normally much louder than the P2 due to higher pressures in the left side of the heart. The S2 heart sound can exhibit persistent (widened) splitting, fixed splitting, paradoxical (reversed) splitting, or the absence of splitting.
Additionally, the semi-recumbent position aids in cardiac function by promoting venous return and optimizing cardiac output. This position is particularly beneficial for patients with heart conditions as it can enhance circulation and cardiac performance.
When a patient is in the semi-recumbent position, the heart sounds are more clearly audible due to the enhanced circulation and the improved respiratory function. The subtle changes in the second heart sound, such as the intensity and splitting of the A2 and P2 components, can provide valuable clues about the patient's cardiac health. For example, an elevated P2 intensity, where P2 is louder than A2, can indicate pulmonary hypertension or an atrial septal defect.
In summary, S2 heart sounds are best heard when patients are semi-recumbent as this position optimizes respiratory and cardiac function, allowing for clearer auscultation of the heart sounds. This position also facilitates the diagnosis of cardiac conditions by enabling a more detailed analysis of the second heart sound components.
Ball Joint Failure: Noises to Warn You
You may want to see also
Explore related products
Diagnoses like pulmonary hypertension can be suspected with close attention to second heart sounds
The second heart sound (S2) is produced by the closure of the aortic and pulmonic valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2. The A2 sound is normally much louder than the P2 due to higher pressures in the left side of the heart. Thus, A2 radiates to all cardiac listening posts (loudest at the right upper sternal border), and P2 is usually only heard at the left upper sternal border. Therefore, the A2 sound is the main component of S2.
The cardiac second sounds can provide valuable clues about the heart's condition. Diagnoses like pulmonary hypertension, severe aortic stenosis, an atrial septal defect, and delays in electrical conduction can be suspected or diagnosed by paying close attention to the second heart sounds.
In pulmonary hypertension, the intensity of P2 is considered elevated if P2 is louder than A2 at the pulmonic region (left parasternal, intercostal space 2). This is because the pulmonary artery is able to tolerate more volume of blood before the pressure above the valve during inspiration due to its lower vascular resistance.
A paradoxical split S2 heart sound occurs when the splitting is heard during expiration and disappears during inspiration, opposite to the physiologic split S2. A paradoxical split S2 occurs in any setting that delays the closure of the aortic valve, including severe aortic stenosis and hypertrophic obstructive cardiomyopathy, or in the presence of a left bundle branch block. A fixed split S2 is caused by an atrial septal defect, which results in a fixed delay in pulmonic valve closure.
Cat Wheezing: What's Wrong and How to Help?
You may want to see also
Frequently asked questions
The second heart sound (S2) is produced by the closure of the aortic and pulmonic valves. The sound produced by the closure of the aortic valve is termed A2, and the sound produced by the closure of the pulmonic valve is termed P2.
The S2 heart sound is heard during the phase of the cardiac cycle known as isovolumetric relaxation. This marks the beginning of diastole.
The S2 heart sound can exhibit persistent (widened) splitting, fixed splitting, paradoxical (reversed) splitting, or the absence of splitting.
