|
ECHONOMY
Tools for Echocardiographic Calculations
Muhamed Saric, MD, PhD
New York University
|
|
 |
1. Diagnosis of Intra-LV Dyssynchrony
|
 | Used in patients being considered for implantation of biventricular
(CRT) devices |
|
| Preferred technique: Color
tissue Doppler in A4C, A3C and A2C views as described
here. |
|
| What to measure: Opposing wall delay (OWD; time difference between S
wave peaks of opposing walls). Report the largest OWD value. |
|
| Abnormal cutoff value : OWD
>65 msec |
|
| |
2. Pacemaker Optimization
|
| Step 1: AV Optimization |
|
| Step 2: VV Optimization |
|
| |
2.1. AV Optimization
|
| Exclude patients in atrial fibrillation; note that AV optimization in
patients with mitral prosthetic valves may be challenging. |
|
| Used in patients with dual-chamber (RA/RV) or biventricular
pacemakers. In patients with biventricular systems, the pacemaker is
usually set to a monochamber LV pacing mode during AV optimization. |
|
| Preferred technique:
Pulsed-wave Doppler of mitral inflow and/or continuous-wave spectral
Doppler VTI of aortic outflow described
here. |
|
| What to measure:
 | Mitral inflow - Look for AV delay at which E and A are separate from
each other, the A wave is not truncated and there is no diastolic mitral
regurgitation. |
| Aortic outflow - Look for AV delay at which the aortic VTI is the
largest. |
| Start with AV delay of 200 msec
and decrease it in 20-msec steps until AV delay is 60 msec.
|
|
|
2.2. VV Optimization
|
| Used in patients with biventricular pacemakers. |
|
| Preferred technique:
Continuous-wave spectral Doppler VTI of aortic outflow described
here. |
|
| Note that VV delay can usually
be programmed from +80 msec
(LV
before RV) to -80 msec
(RV before LV). |
|
| What to measure: Look for VV delay at which the VTI is the largest.
Optimal VTI is often at VV delay = +20 msec (LV before RV). |
|
| When VV delay is used to pre-excite RV (negative VV delay), AV delay
obtained in step 1 above (initial AV delay) should be adjusted as follows:
: New AV delay = Initial AV delay
- VV delay of RV pre-excitation
|
|
2.3. Intra-LV Optimization
|
|
Once a biventricular pacemaker is implanted, intra-LV
optimization is usually unfeasible. |
|
| Measurements of intra-LV delays are primarily used to assess for LV
dyssynchrony prior to biventricular pacemaker implantation as described
here.
|
|
References
|
| Gorcsan J 3rd, Abraham T, Agler DA, Bax JJ,
Derumeaux G, Grimm RA, Martin R, Steinberg JS, Sutton MS, Yu CM; American
Society of Echocardiography Dyssynchrony Writing Group.
Echocardiography for cardiac resynchronization therapy: recommendations for
performance and reporting--a report from the American Society of
Echocardiography Dyssynchrony Writing Group endorsed by the Heart Rhythm
Society. J Am Soc
Echocardiogr. 2008 Mar;21(3):191-213. Barold SS, Ilercil A, Herweg
B. Echocardiographic optimization of the atrioventricular and
interventricular intervals during cardiac resynchronization.
Europace.
2008 Nov;10 Suppl 3:iii88-95. |
| |
