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ECHONOMY
Tools for Echocardiographic Calculations
Muhamed Saric, MD, PhD
New York University
 

AV Delay

Diagnosis of AV Delay
Technique:
Pulsed-wave Doppler of mitral inflow

Normal AV Delay:
When atrioventricular (AV) conduction is normal, mitral E and A wave are distinct (not fused) and A wave ends shortly (about 40-60 msec) before the onset of the next QRS on the EKG.

AV Delay Too Long:
The A wave gets closer and closer to the E wave as the AV delay (PR interval) gets longer and longer until E and A fuse into one wave. Furthermore, there may be diastolic mitral regurgitation after A way ends and before the next QRS starts.

AV Delay Too Short:
Terminal portion of the A wave gets progressively truncated as the AV delay (PR interval) gets shorter and shorter until the A wave completely disappears.

Source: J Am Soc Echocardiogr. 2008 Mar;21(3):191-213.
 

Timing of AV Optimization
For biventricular pacemakers, AV optimization (during monochamber LV pacing) should be done before VV optimization.
 

AV Optimization: Iterative Mitral Inflow Method
1. Obtain pulsed wave Doppler of mitral inflow at varying AV delays.

2. Start with AV delay of 200 msec; progressively shorten the AV delay by 20 msec until AV delay reaches 60 msec.

3. Select the AV delay at which mitral E and A waves are most distinct, no A wave truncation is observed an no diastolic mitral regurgitation is seen.
 

AV Optimization: Iterative Aortic Outflow Method
  1. Obtain continuous wave Doppler velocity-time integral (VTI)  of aortic valve outflow  at varying AV delays.
  2. Start with AV delay of 200 msec; progressively shorten the AV delay by 20 msec until AV delay reaches 60 msec.
  3. Select the AV delay at which the VTI (a proxy for LV stroke volume) is the largerst.
     

Caveats
  1. AV optimization may be difficult or impossible in non-sinus rhythm.
  2. AV optimization may be problematic in patients with mitral prosthetic valves.

 

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.