1. What is Aortic Valve VTI?

The Velocity Time Integral (VTI) is the integral of blood flow velocity over time across the aortic valve. It represents the distance blood travels during one cardiac cycle and is used to calculate stroke volume and cardiac output.

2. How Does the Calculator Work?

The calculator uses the integral of velocity over time:

Where:

• \( v(t) \) — Blood flow velocity (m/s) as function of time
• \( t1 \) — Start time of ejection period
• \( t2 \) — End time of ejection period

Explanation: This simplified version multiplies peak velocity by ejection time. In clinical practice, the actual integral is calculated by tracing the Doppler waveform.

3. Importance of VTI Measurement

Details: VTI is essential for calculating stroke volume (SV = VTI × CSA) and cardiac output (CO = SV × HR). It's used in assessing valve stenosis, cardiac function, and hemodynamics.

4. Using the Calculator

Tips: Enter peak velocity in m/s and ejection time in seconds. For accurate clinical measurements, use Doppler echocardiography to trace the velocity-time curve.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal aortic valve VTI?
A: Normal range is typically 15-25 cm. Lower values may indicate reduced stroke volume, while higher values suggest increased flow.

Q2: How does VTI relate to stroke volume?
A: Stroke volume = VTI × cross-sectional area of the left ventricular outflow tract (LVOT).

Q3: When is VTI most clinically useful?
A: In assessing aortic stenosis severity, calculating cardiac output, and evaluating hemodynamics in shock states.

Q4: What affects VTI accuracy?
A: Proper Doppler alignment, correct velocity scale, and accurate tracing of the spectral envelope.

Q5: Can VTI be used for other valves?
A: Yes, the same principle applies to mitral, pulmonary, and tricuspid valves, though normal ranges differ.