From the Guidelines
The S2 heart sound is a result of the closure of the semilunar valves, specifically the aortic and pulmonic valves, at the beginning of ventricular diastole. This sound occurs when the ventricles begin to relax and the pressure in the ventricles drops below the pressure in the aorta and pulmonary artery, causing blood to flow back toward the ventricles. The semilunar valves then snap shut to prevent this backflow, creating the S2 sound. The S2 sound is typically higher-pitched and shorter than the S1 sound and is best heard at the base of the heart. Normally, S2 has two components: A2 (aortic valve closure) and P2 (pulmonic valve closure), which may be heard separately during inspiration due to respiratory variation. This physiological splitting occurs because inspiration decreases intrathoracic pressure, increasing venous return to the right heart and slightly delaying pulmonic valve closure while aortic valve closure remains relatively constant 1.
Some key points to consider when evaluating the S2 heart sound include:
- The presence of a single or paradoxically split second heart sound (S2) can confirm the presence of severe aortic stenosis 1
- A normally split second heart sound is a reliable finding in excluding the possibility of severe aortic stenosis 1
- The S2 sound can be affected by various factors, including respiratory variation, and should be evaluated in the context of the patient's overall clinical presentation 1
- Echocardiography can provide valuable information about the severity of valve stenosis and regurgitation, but should be used in conjunction with a thorough history and physical examination 1
In clinical practice, it is essential to consider the S2 heart sound as part of a comprehensive evaluation of the patient's cardiovascular system, taking into account the patient's symptoms, medical history, and physical examination findings. By doing so, clinicians can make more accurate diagnoses and develop effective treatment plans that prioritize morbidity, mortality, and quality of life.
From the Research
S2 Heart Sound
- The S2 heart sound is a result of the closure of the pulmonary and aortic valves.
- There is no direct evidence in the provided studies to support the claim of what the S2 heart sound is a result of, as the studies focus on pulmonary hypertension in patients with aortic stenosis and mitral regurgitation 2, 3, 4, 5, 6.
- However, it is known that the S2 heart sound is related to the pulmonary and aortic valves, and pulmonary hypertension can affect the sound due to changes in pressure and valve function.
- The studies provided discuss the relationship between pulmonary hypertension and aortic stenosis, but do not directly address the S2 heart sound 2, 3, 4, 5, 6.
Pulmonary Hypertension and Aortic Stenosis
- Pulmonary hypertension is a common complication of aortic stenosis, and is associated with increased morbidity and mortality 2, 3, 4, 5, 6.
- The studies discuss the determinants and prognostic significance of pulmonary hypertension in patients with aortic stenosis, including exercise-induced pulmonary hypertension 3, 6.
- However, the relationship between pulmonary hypertension and the S2 heart sound is not directly addressed in the provided studies.