As the valves close, S1 and S2 are produced.

• S1 indicates closure of the mitral and tricuspid valves, is heard the loudest in those areas of the heart and occurs during systole.

• S2 indicates closure of the aortic and pulmonic valves, is heard the loudest in those areas of the heart and occurs at the end of systole and beginning of diastole.

• If there is stenosis in the valve, a click may be heard as the valve snaps open.

At times, there are more than two sounds heard. So, instead of just “Lub, Dub, Lub, Dub”, other sounds such as an S3 and S4 gallop are present. Both are low pitched sounds and heard best with the bell of stethoscope. A summation gallop is when both S3 and S4 are heard.

S3 (gallop)
• Caused by turbulence on ventricular filling.
• Indicates heart failure and will be heard before crackles develop.
• Heard in systolic dysfunction which is a problem with contraction.
• An S3 may be normal in children and those under the age of 40 years.

S4 (gallop)
• Produced when the atria contract.
• Heard in several conditions, including myocardial ischemia or infarction.
• Will also be heard in hypertension, ventricular hypertrophy, AV blocks, and severe aortic or pulmonic stenosis.
• Heard in diastolic dysfunction, which is a problem with filling.
• It will not be heard in atrial fibrillation due to the lack of coordinated atrial contraction.

Some medical professionals feel like they want to “listen” to audio recordings of heart sounds. While this may be beneficial, it is difficult to translate what is heard on a demo into clinical practice.

Instead, try listening for “sounds” in words which can be used to describe the heart sounds.

Left-sided events are loudest on expiration
• Mitral and aortic valve closure which typically occur before the tricuspid and pulmonic.
• S3 and S4 are heard at the mitral area with left ventricular failure and left ventricular myocardial infarction.

Right-sided events are loudest on inhalation
• Tricuspid and pulmonic valve closure.
• S3 and S4 are heard at the tricuspid area with right ventricular failure and right ventricular infarction in conjunction with an inferior wall MI.

Splits occur when the right-side events occur before the left-side
• Split S1 (tricuspid before mitral) sounds like “La-Lub-Dub”. It is always abnormal and is heard in right bundle branch block and with PVCs.
• Split S2 (pulmonic before aortic) sounds like “Lub-Da-Dub”. It is considered normal on inspiration. It is abnormal when heard on exhalation and is heard in atrial septal defect, right or left bundle branch block, and pulmonary hypertension.

Heart tones are an important part of assessment and changes often signify deterioration. Developing a systematic approach and consistently listening to all four areas of the heart valves leads to enhanced expertise in clinical practice. The most important sounds to evaluate are S1 and S2 and determine if an S3 or S4 are present if an extra sound is heard. Listening for the sounds of murmurs such as “Swish-Dub” (systolic murmur) and “Lub-Swish-Dub” (diastolic murmur) should also be incorporated into clinical practice.

To enhance care provided for all patients, check out Advanced Assessment in Clinical Practice. It is on-line, on-demand, with voice-over-power-point. The extensive handout will provide an invaluable reference for future use. It is written in an outline format and includes various tables and bullet points to make the information easy to review and retain. Activities and “Memory Hints” are presented throughout to reinforce knowledge at the clinical level and critical thinking.