Fact Check: Are ejection fraction and stroke volume the same?

Are Ejection Fraction and Stroke Volume the Same?

The claim under scrutiny is whether ejection fraction (EF) and stroke volume (SV) are the same. These terms are frequently used in cardiovascular physiology, but their definitions and implications may lead to confusion.

What We Know

1. Definitions:

   • Ejection Fraction (EF): EF is defined as the percentage of blood that is ejected from the left ventricle during each heartbeat relative to the total volume of blood in the ventricle at the end of diastole (end-diastolic volume, EDV). Mathematically, it is expressed as: [ EF = \frac{SV}{EDV} \times 100 ] where SV is stroke volume 13.
   • Stroke Volume (SV): SV is the volume of blood pumped from the ventricle with each heartbeat. It is calculated as the difference between the end-diastolic volume (EDV) and the end-systolic volume (ESV): [ SV = EDV - ESV ] 14.

2. Normal Ranges:

   • The normal range for EF is typically between 55% and 75% 5.
   • SV varies based on individual factors such as heart size and physical condition, but specific normal ranges are less frequently cited.

3. Clinical Relevance:

   • Both EF and SV are critical indicators of heart function. EF is often used in clinical settings to assess the heart's pumping efficiency, while SV provides insight into the volume of blood being circulated with each heartbeat 29.

Analysis

Source Evaluation

1. StatPearls: The information from StatPearls is derived from a reputable medical database and is authored by medical professionals. It provides a detailed explanation of both EF and SV, making it a reliable source for understanding these concepts 12. However, it is essential to note that StatPearls is a resource that may be used for educational purposes, and while it is generally credible, it should be corroborated with other peer-reviewed literature.

2. Wikipedia: The Wikipedia entries on ejection fraction and stroke volume provide a broad overview and are often updated by various contributors. While Wikipedia can be a useful starting point, it is not always the most reliable source due to potential biases and inaccuracies in the editing process. However, the information presented aligns with definitions found in more authoritative sources 34.

3. FindAnyAnswer and Osmosis: These sources offer simplified explanations of the differences between EF and SV. However, they may lack the depth and rigor found in peer-reviewed medical literature. Their reliability can be questioned, especially since they may cater to a general audience rather than medical professionals 58.

4. Clinical Guidelines: Articles from clinical guidelines or peer-reviewed journals would provide the most reliable information regarding the definitions and clinical implications of EF and SV. Such sources would be beneficial for a more comprehensive understanding of how these measurements are used in practice.

Methodology and Evidence

The definitions provided by the sources are consistent with established medical knowledge. However, the claim that EF and SV are the same is incorrect, as they measure different aspects of cardiac function. EF is a ratio expressed as a percentage, while SV is an absolute volume. This distinction is critical for understanding cardiac performance.

Conflicts of Interest

Most of the sources cited do not appear to have clear conflicts of interest. However, it is always prudent to consider the potential for bias in any medical literature, especially those that may be funded by organizations with vested interests in cardiovascular health.

Conclusion

Verdict: False

The claim that ejection fraction (EF) and stroke volume (SV) are the same is false. The key evidence supporting this conclusion lies in the definitions of the two terms: EF is a percentage that indicates the efficiency of the heart's pumping ability, while SV is an absolute volume of blood ejected with each heartbeat. This fundamental difference highlights that they measure distinct aspects of cardiac function.

It is important to note that while both EF and SV are critical indicators of heart health, they serve different purposes in clinical assessments. The available evidence consistently supports the distinction between these two measurements, although the nuances of their clinical implications may vary based on individual patient circumstances.

However, it is essential to acknowledge that the understanding of these concepts can evolve with ongoing research, and new findings may further refine their definitions and applications. Readers should remain aware of the limitations in the available evidence and the potential for updates in medical knowledge.

As always, it is advisable for readers to critically evaluate information and consult multiple sources when seeking to understand complex medical concepts.

Sources

1. Left Ventricular Ejection Fraction - StatPearls - NCBI Bookshelf. Link
2. Left Ventricular Ejection Fraction - StatPearls. Link
3. Ejection fraction - Wikipedia. Link
4. Stroke volume - Wikipedia. Link
5. What is difference between stroke volume and ejection fraction? Link
6. Key Concept: Ejection fraction is another character in the stroke ... Link
7. Stroke Volume And Ejection Fraction: What's The Relationship? Link
8. Stroke volume, ejection fraction, and cardiac output - Osmosis. Link
9. Ejection fraction (EF): Physiology, Measurement & Clinical Evaluation. Link
10. Stroke volume, ejection fraction, and cardiac output - Osmosis. Link