What is the relationship between an S4 heart sound and diastolic dysfunction?

From the Guidelines

The S4 heart sound is closely associated with diastolic dysfunction, particularly in its early stages, and its presence should prompt further cardiac evaluation including echocardiography to assess ventricular function, wall thickness, and other parameters of diastolic function. Diastolic dysfunction occurs when the left ventricle becomes stiff and cannot relax properly during diastole, leading to impaired filling. An S4 sound is produced when blood from the atrium enters a non-compliant ventricle during late diastole, causing vibrations that can be heard as a low-pitched "lub" just before the normal S1 sound. This finding is particularly common in conditions that cause left ventricular hypertrophy such as hypertension, aortic stenosis, and hypertrophic cardiomyopathy.

Key Points to Consider

• The relationship between an S4 heart sound and diastolic dysfunction is well-established, with the S4 sound being a marker of abnormal diastolic function 1.
• Diastolic dysfunction can be evaluated using echocardiography, which can assess ventricular function, wall thickness, and other parameters of diastolic function 1.
• The presence of an S4 sound should prompt further cardiac evaluation, including echocardiography, to assess for diastolic dysfunction and guide management 1.
• Management of diastolic dysfunction focuses on treating the underlying cause, typically with medications like ACE inhibitors or ARBs for hypertension, beta-blockers to improve diastolic filling time, and diuretics to reduce fluid overload.
• Lifestyle modifications, including sodium restriction, weight loss, and regular exercise, are also important in managing diastolic dysfunction.

Diagnostic Evaluation

• Echocardiography is a key diagnostic tool in evaluating diastolic dysfunction, and can assess parameters such as mitral inflow velocity, mitral annular velocity, and left atrial volume index 1.
• The use of advanced echocardiographic techniques, such as tissue Doppler imaging and speckle tracking, can provide additional information on diastolic function and guide management 1.
• The assessment of diastolic function should include evaluation of left ventricular relaxation, restoring forces, and lengthening load, as well as estimation of left ventricular filling pressures 1.

From the Research

Relationship between S4 Heart Sound and Diastolic Dysfunction

• The S4 heart sound is associated with diastolic dysfunction, as it is often heard in patients with conditions that lead to diastolic dysfunction, such as hypertension and heart failure 2, 3, 4, 5, 6.
• Diastolic dysfunction is characterized by impaired relaxation and compliance of the left ventricle, leading to increased filling pressure and symptoms of heart failure 2, 3, 4, 5, 6.
• The presence of an S4 heart sound can indicate increased stiffness of the left ventricle, which is a hallmark of diastolic dysfunction 5, 6.
• Echocardiography is an important tool for diagnosing diastolic heart dysfunction, and can help identify indicators of diastolic dysfunction, such as abnormal left ventricular relaxation and stiffness 5.

Clinical Implications

• Diastolic heart failure is an important clinical disorder, mainly seen in elderly patients with hypertensive heart disease, and is associated with a lower annual mortality rate compared to heart failure with systolic dysfunction 3.
• Early recognition and appropriate therapy of diastolic dysfunction is advisable to prevent further progression to diastolic heart failure and death 3, 4.
• Treatment of diastolic dysfunction is often empirical and lacks clear-cut pathophysiologic concepts, but may include calcium channel blockers, beta-blockers, ACE-inhibitors, and ARB, as well as nitric oxide donors 3, 4.