Normal Stroke Volume
Normal stroke volume in adults ranges from 50 to 90 mL per beat at rest. 1 This represents the volume of blood ejected from the left ventricle with each cardiac contraction.
Definition and Measurement
Stroke volume (SV) is defined as the amount of blood ejected from the heart with each contraction. It can be calculated as the difference between left ventricular end-diastolic volume and end-systolic volume, or measured using various echocardiographic techniques:
- Doppler echocardiography
- 2D echocardiography
- 3D echocardiography
Normal Values by Demographics
Sex Differences
- Men typically have higher stroke volumes than women
- When indexed to body surface area (stroke volume index), these differences persist 2
Age-Related Changes
- Stroke volume index decreases with aging 2
- This decline is observed across all measurement techniques
Ethnic Variations
- Whites tend to have larger stroke volumes
- Asians typically have smaller stroke volumes
- These differences persist even after normalization for body surface area 2
Measurement Techniques and Considerations
Echocardiographic Methods
- Different echocardiographic techniques (Doppler, 2D, and 3D) yield different values
- These methods are not interchangeable 2
- 2D measurements typically yield lower values than Doppler or 3D methods
Clinical Context
- Normal stroke volume assumes normal heart rate (50-80 bpm) 1
- Values are valid for near normal or normal diastolic filling periods
- Measurements may be affected by:
- Heart rate
- Left atrial compliance
- Left ventricular compliance
- Presence of valvular disease
Abnormal Stroke Volume
Low Stroke Volume
- May indicate:
- Systolic dysfunction
- Valvular stenosis
- Hypovolemia
- Restrictive cardiomyopathy
High Stroke Volume
- May indicate:
- Chronic aortic or mitral regurgitation
- High-output states
- Athletic heart
Clinical Implications
Stroke volume is a critical parameter for assessing:
- Cardiac function
- Hemodynamic status
- Response to therapeutic interventions
- Valvular function
When evaluating stroke volume, it's important to consider the measurement technique used, as well as the patient's age, sex, and ethnicity, as these factors significantly influence normal values.