Where is s1 louder

This forces the tricuspid valve closed earlier, resulting in complete overlap of M1 and T1, and thus no audible split S1 sound. Four factors affect the intensity of the first heart sound. Because the M1 portion of S1 is much louder than T1, it is only important to discuss what affects the intensity of M1. The second heart sound 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.

Like the S1 heart sound, the S2 sound is described regarding splitting and intensity. The S2 heart sound can exhibit persistent widened splitting, fixed splitting, paradoxical reversed splitting or the absence of splitting.

The S2 heart sound intensity decreases with worsening aortic stenosis due to immobile leaflets. In severe aortic stenosis, the A2 component may not be audible at all. Normally, A2 occurs just before P2, and the combination of these sounds make up S2. A physiologic split S2 occurs when the A2 sound precedes P2 by a great 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 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. During expiration, the distance narrows, and the split S2 is no longer audible. A paradoxical split S2 heart sound occurs when the splitting is heard during expiration and disappears during inspiration — opposite of 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.

Enlarge Persistent Widened Split S2 Persistent widened splitting occurs when both A2 and P2 are audible during the entire respiratory cycle, and the splitting becomes greater with inspiration due to increased venous return and less prominent with expiration.

This differs from a fixed split S2, which exhibits the same amount of splitting throughout the entire respiratory cycle and is explained below. Any condition that causes a nonfixed delay in the closure of the pulmonic valve, or early closure of the aortic valve, will result in a wide split S2. In mitral regurgitation, this is due to a large proportion of the left ventricular stroke volume entering the left atrium, causing the left ventricular pressure to decrease faster.

Enlarge Fixed Split S2 A fixed split S2 is a rare finding on cardiac exam; however, when found, it almost always indicates the presence of an atrial septal defect. A fixed split S2 occurs when there is always a delay in the closure of the pulmonic valve, and there is no further delay with inspiration; compare this to a widened split S2, as described above. To explore why an ASD results in a fixed split S2, we must consider the altered cardiac hemodynamics present, which result in a fixed delay in PV closure.

During inspiration, as usual, there is an increase in venous return to the right side of the heart and thus increased flow through the PV — delaying its closure. The alteration in a person with an ASD occurs during expiration. As the person expires, the pressure in the right atrium decreases because there is less venous return. The decreased pressure allows more blood to flow abnormally through the ASD from the high pressured left atrium to the right atrium, ultimately resulting again in increased flow through the pulmonic valve — again, delaying its closure.

The S3 sound is actually produced by the large amount of blood striking a very compliant LV. Enlarge If the LV is not overly compliant, as is in most adults, a S3 will not be loud enough to be auscultated. A S3 can be a normal finding in children, pregnant females and well-trained athletes; however, a S4 heart sound is almost always abnormal. A S3 can be an important sign of systolic heart failure because, in this setting, the myocardium is usually overly compliant, resulting in a dilated LV; this can be seen in the image below.

During inspiration you should hear the inspiratory splitting of S2 into A2 and P2. To the untrained ear this sounds more like a prolongation of sound rather than two distinct sounds. In general the interval between A2 and P2 is quite short, although in some situations the patient may have a widened interval. Next, listen for splitting of S2 to disappear during expiration.

If there is splitting during expiration, this is abnormal and is termed paradoxical splitting. Click on the interactive icon to practice listening to the intensity and splitting of S1 and S2. The First and Second Heart Sounds When listening to the first and second heart sounds with the diaphragm of the stethoscope, note the intensity of each sound, note if each is a single or split sound, and note any respiratory variation.

Best Heart Position During Auscultation Because S1 heart sounds occur when the mitral and tricuspid valve close, the best heart is locations for the stethoscope chestpiece are at the tricuspid left lower sternal border and mitral cardiac apex locations. Listen Listening Tips Audio Playback. Heart Sounds Reference Guide Our auscultation reference guide provides quick access to this sound as well as many other adventitious sounds.

Each sound is described also with an audio recording and waveform. Heart Sounds Reference Guide. Quick Links to Other Breath Sounds While we have many breath sound lessons and quick references on this website. Basics of Lung Sounds The goal of this basic course in lung sounds is to improve auscultation observational skills. We focus on describing important breath sounds and in providing recordings of each.

Many students find that waveform tracings aid in learning lung sounds; we have included dynamic moving cursor waveforms with each lesson. The anatomy pages use illustrations to reveal an example of each lung sound anatomy not yet available on smartphones. Intermediate Lung Sounds The goal of this intermediate course is to expand your observational skills when auscultating breath sounds.