Mitral stenosis deceleration time
MS DT · Same CW inflow trace as the pressure half-time; DT is the extrapolation of the E-wave downslope to baseline
Normal range & thresholds
MVA ≈ 759 / DT, which follows directly from MVA = 220/PHT and PHT = 0.29 × DT.[43]
Severe mitral stenosis (MVA ≤1.5 cm²) therefore corresponds to a DT ≥≈520 ms, and very severe (≤1.0 cm²) to a DT ≥≈760 ms. For the normal, non-stenotic mitral valve the equivalent measurement is the diastolic-function deceleration time of card 15, where 160–240 ms is normal — the same measurement carries completely different meaning depending on whether the valve is obstructed, and confusing the two is a real reporting hazard.
Severe mitral stenosis (MVA ≤1.5 cm²) therefore corresponds to a DT ≥≈520 ms, and very severe (≤1.0 cm²) to a DT ≥≈760 ms. For the normal, non-stenotic mitral valve the equivalent measurement is the diastolic-function deceleration time of card 15, where 160–240 ms is normal — the same measurement carries completely different meaning depending on whether the valve is obstructed, and confusing the two is a real reporting hazard.
Pathophysiology
Identical physiology to the pressure half-time, of which the deceleration time is simply the un-scaled form. The clinical value of reporting DT rather than PHT is that DT is what the machine measures directly and what the eye can check on the spectral display, so an implausible PHT can be caught by looking at the slope. Its limitation is identical: the slope encodes orifice area and the compliance of the receiving chambers, and the equation cannot separate them.[43]
Raised by
- Increasing severity of mitral stenosis
- Significant aortic regurgitation (falsely long → over-estimated severity)
- Reduced left ventricular compliance — elderly, hypertensive, hypertrophied, restrictive
- Bradycardia and first-degree AV block
Lowered by
- Atrial septal defect; recent balloon valvuloplasty (both falsely short)
- Tachycardia; high output states
- Coexisting significant mitral regurgitation
- Successful relief of the obstruction
Technique & pitfalls
- Extrapolate the mid-diastolic slope to the zero baseline; do not measure to where the tracing meets the baseline, and do not use the initial steep segment of a bilinear descent.
- Sweep 100 mm/s, CW Doppler aligned with inflow.
- Average 5–10 cycles in atrial fibrillation; report the heart rate.
- State clearly in the report whether a deceleration time is being used as a diastolic-function measure or as a mitral stenosis measure — and never quote the 160–240 ms normal range for a stenotic valve.
- Cross-check with planimetry, as for the pressure half-time.
Pseudo-change & artefact
- Every artefact listed for the pressure half-time applies unchanged: aortic regurgitation, altered compliance, atrial septal defect, tachycardia, recent valvuloplasty, and slope-selection error.
- The additional hazard is contextual misreading — reporting a long DT in a stenotic valve as ‘impaired relaxation’, or a short DT in a stenotic valve as ‘restrictive filling’. Neither statement is meaningful once the mitral valve is obstructed.
- Inter-observer variability of 20–30 ms translates into a clinically meaningful change in the derived area.
Treatment thresholds
- The same thresholds as the pressure half-time and mitral valve area (cards 34 and 35): MVA ≤1.5 cm² defines severe mitral stenosis and, with symptoms, indicates intervention (class I), by balloon valvuloplasty where the anatomy is favourable.[6,7,45]
- In the 2025 ASE diastolic algorithm, a deceleration time ≤160 ms in atrial fibrillation is one of the four primary criteria for elevated left atrial pressure — a completely different use of the same measurement, and one that presupposes a non-stenotic valve.[2]
- No intervention rests on DT alone.
Next step
- Next: planimetry and mean gradient; reconcile all three.
- Then: Wilkins score and TOE for left atrial appendage thrombus if intervention is contemplated.[45]
- Then: exercise echocardiography for discordant symptoms; pulmonary pressures at rest and on exercise.[28]
- Then: Heart Team; anticoagulation and rate control in the interim.
Drugs
- As for the pressure half-time: rate-limiting drugs alter the measurement as well as the symptoms, diuretics relieve congestion, vitamin K antagonists are the anticoagulant of choice in rheumatic disease, and nothing changes the orifice.[40]
Reversibility
Identical to the pressure half-time: immediate mechanical improvement with valvuloplasty or surgery, slow progression untreated, no pharmacological reversibility.[45]