What is the formula to assess mitral valve Diastolic Velocity Index (DVI)?

Formula for Mitral Valve Diastolic Velocity Index (DVI)

The formula for mitral valve Diastolic Velocity Index (DVI) is the ratio of IVRT (Isovolumic Relaxation Time) to TE-e' (time interval between onset of mitral E velocity and annular e' velocity). 1

Understanding the Components

1. IVRT (Isovolumic Relaxation Time):

   • The time interval between aortic valve closure and mitral valve opening
   • Normally ≤70 msec in healthy subjects
   • Prolonged in patients with impaired LV relaxation but normal LV filling pressures
   • Shortens when left atrial pressure (LAP) increases

2. TE-e' (Time interval):

   • The time delay between the onset of mitral inflow E velocity and the onset of early diastolic mitral annular velocity (e')
   • Increases in patients with impaired relaxation
   • Reflects LV relaxation properties

Clinical Significance and Application

• DVI (IVRT/TE-e') correlates well with mean pulmonary capillary wedge pressure (PCWP) and left atrial pressure (LAP) 1, 2
• Particularly valuable in patients with mitral valve disease where other parameters like E/e' ratio may be less reliable 1, 3
• An IVRT/TE-e' ratio < 3 predicts PCWP > 15 mm Hg in patients with mitral regurgitation 1

Measurement Technique

• Obtain IVRT using continuous wave (CW) or pulsed wave (PW) Doppler
• Measure TE-e' by recording:
  1. Mitral inflow E velocity onset using pulsed wave Doppler
  2. Mitral annular e' velocity onset using tissue Doppler imaging
  3. Calculate the time difference between these two events

Advantages Over Other Methods

• Less load-dependent than conventional Doppler parameters 4
• Remains accurate in settings where E/e' ratio is unreliable:
  • Severe mitral regurgitation 3
  • Mitral stenosis 1
  • Mitral annular calcification
  • Prosthetic mitral valves

Clinical Pitfalls and Considerations

• Measurement requires precise timing and matching of cardiac cycles
• More challenging to acquire in patients with:
  • Atrial fibrillation
  • Tachycardia
  • Poor acoustic windows
• Requires careful attention to location, gain, and filter settings 1
• Septal e' measurements may be more reliable than lateral measurements for overall LV relaxation assessment 5

When to Use DVI

• When assessing diastolic function in patients with mitral valve disease
• When E/e' ratio yields indeterminate results
• As part of a comprehensive diastolic function assessment in patients with heart failure with preserved ejection fraction (HFpEF) 6
• When standard diastolic parameters are inconclusive or contradictory

This index provides valuable information about LV relaxation and can help estimate filling pressures in clinical scenarios where conventional parameters may be limited.