From the Guidelines
S3 and S4 heart sounds are best heard at the apex of the heart (left ventricular area) or the left sternal border with the patient in the left lateral decubitus position, using the bell of the stethoscope. The location for auscultation of these sounds is crucial for accurate detection. Key points to consider when listening for S3 and S4 heart sounds include:
- Using the bell of the stethoscope to detect these low-pitched sounds
- Placing the patient in the left lateral decubitus position to bring the heart closer to the chest wall
- Listening at the apex of the heart (left ventricular area) or the left sternal border for both S3 and S4 sounds
- S3 sounds occur early in diastole, while S4 sounds occur just before S1 during late diastole 1. It is essential to note that the provided evidence does not directly describe the location for auscultation of S3 and S4 heart sounds, but based on general medical knowledge and the information given, the apex and left sternal border are the recommended locations. The clinical significance of S3 and S4 heart sounds, as mentioned, typically relates to volume overload or ventricular dysfunction for S3, and decreased ventricular compliance often due to hypertension, aortic stenosis, or ischemic heart disease for S4.
From the Research
Location of S3 and S4 Heart Sounds
- The S3 (third heart sound) and S4 (fourth heart sound) can be heard in specific locations during auscultation, as noted in 2.
- The S3 sound is typically heard over the apex of the heart or the xiphoid or epigastric area, especially in patients with cardiac decompensation associated with coronary heart disease, hypertensive heart disease, and dilated cardiomyopathy 2.
- The S4 sound is most frequently found in patients who have coronary heart disease and hypertension, and it can be heard over the apex of the heart or the xiphoid or epigastric area 2.
Detection of S3 and S4 Heart Sounds
- The detection of S3 and S4 heart sounds can be improved using digital signal processing techniques, such as the Hilbert-Huang Transform (HHT) 3.
- A statistical analysis of phonocardiographic (PCG) signals can also be used to analyze the characteristics of the four heart sounds, including S3 and S4 4.
- The presence of S3 and S4 heart sounds can be associated with myocardial fibrosis in patients with hypertrophic cardiomyopathy, as noted in 5.
Clinical Significance of S3 and S4 Heart Sounds
- The S3 heart sound is often associated with cardiac decompensation and heart failure, while the S4 heart sound is associated with coronary heart disease and hypertension 2, 5.
- The detection of S3 and S4 heart sounds can be useful in the diagnosis and management of patients with heart failure, as noted in 6.