Stroke Volume Calculator LVOT VTI

Stroke Volume Equation:

\[ SV = \pi \times \left(\frac{LVOT\ diameter}{2}\right)^2 \times VTI \]

Stroke Volume (SV):

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1. What is Stroke Volume?

Stroke Volume (SV) is the volume of blood pumped by the left ventricle of the heart in one contraction. It's a key parameter in assessing cardiac function and is used to calculate cardiac output (CO = SV × heart rate).

2. How Does the Calculator Work?

The calculator uses the LVOT-VTI method equation:

\[ SV = \pi \times \left(\frac{LVOT\ diameter}{2}\right)^2 \times VTI \]

Where:

\( LVOT\ diameter \) — Left ventricular outflow tract diameter (cm)
\( VTI \) — Velocity time integral (cm)
\( \pi \) — Mathematical constant (~3.1416)

Explanation: The equation calculates the stroke volume by multiplying the cross-sectional area of the LVOT (derived from the diameter) by the distance blood travels during systole (VTI).

3. Clinical Importance

Details: Stroke volume measurement is essential for evaluating cardiac function, diagnosing heart failure, and monitoring response to therapy. It's particularly useful in echocardiography for non-invasive assessment.

4. Using the Calculator

Tips:

Measure LVOT diameter precisely from parasternal long-axis view
Obtain VTI from pulsed-wave Doppler at the LVOT
Enter values in centimeters
Normal stroke volume range is typically 60-100 mL

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for stroke volume?
A: In healthy adults, stroke volume typically ranges from 60-100 mL per beat at rest.

Q2: How does this relate to cardiac output?
A: Cardiac output = Stroke Volume × Heart Rate. Normal cardiac output is 4-8 L/min.

Q3: What are common sources of error in this calculation?
A: Errors can come from inaccurate LVOT diameter measurement (most critical), improper Doppler alignment, or failure to average multiple beats in irregular rhythms.

Q4: When is this method not appropriate?
A: May be less accurate with significant LVOT obstruction, aortic regurgitation, or irregular rhythms like atrial fibrillation.

Q5: How does this compare to other methods of measuring stroke volume?
A: The LVOT-VTI method is non-invasive and widely used in echocardiography, though other methods like thermodilution (invasive) or 3D echocardiography may be used in specific situations.