Fractional shortening

Fractional shortening (FS) is a term used in cardiology to describe the fraction of any diastolic dimension that is lost during systole. It is a measure of left ventricular function and is calculated by the formula:

\[FS = \frac{LVEDD - LVESD}{LVEDD} \times 100\]

where LVEDD is the left ventricular end-diastolic diameter and LVESD is the left ventricular end-systolic diameter. The measurement is expressed as a percentage, indicating the proportion of the diastolic dimension that is reduced during systole.

Clinical Significance

Fractional shortening is an important parameter in the evaluation of heart function, particularly the performance of the left ventricle, which is crucial for pumping blood throughout the body. A normal FS value ranges from 25% to 45%. Values below this range may indicate heart failure, dilated cardiomyopathy, or other conditions leading to reduced heart function. Conversely, values above this range can be seen in conditions such as hypertrophic cardiomyopathy.

Measurement

Fractional shortening is typically measured using echocardiography, a non-invasive imaging technique that uses ultrasound waves to create images of the heart. This method allows for the direct visualization of heart structures, including the left ventricle, and the measurement of its dimensions during the cardiac cycle.

Advantages and Limitations

One of the main advantages of FS is its simplicity and ease of measurement, making it a quick and non-invasive method for assessing left ventricular function. However, it has limitations. FS does not account for changes in heart size or shape that may affect its function. It also does not provide information on the function of the right ventricle or other parts of the heart. Furthermore, its accuracy can be affected by the quality of the echocardiographic images and the precision of the measurements.

Comparison with Other Measures

Fractional shortening is one of several parameters used to assess cardiac function. Another commonly used measure is the ejection fraction (EF), which assesses the volume of blood pumped out of the left ventricle with each heartbeat relative to its filled volume. While EF provides a more direct measure of the heart's pumping ability, FS offers a simpler and quicker assessment of left ventricular function, making it a useful tool in clinical practice.

Conclusion

Fractional shortening is a valuable parameter for evaluating left ventricular function in clinical cardiology. Despite its limitations, its simplicity and non-invasive nature make it an important tool in the initial assessment and monitoring of patients with heart disease.