Echocardiographic optimization of the atrioventricular and interventricular intervals during cardiac resynchronization

Europace. 2008 Nov;10 Suppl 3:iii88-95. doi: 10.1093/europace/eun220.


An optimized atrioventricular (AV) interval can maximize the benefits of cardiac resynchronization therapy (CRT). If programmed poorly, it may curtail beneficial effects of CRT. AV optimization will not convert non-responder to responder, but may convert under-responder to improved status. There are many echocardiographic techniques for AV optimization but there is no universally accepted gold standard. The optimal AV delay varies with time, necessitating periodic re-evaluation. As the optimal AV delay may lengthen on exercise, a rate-adaptive AV delay should not be routinely programmed. Intra- and interatrial conduction delays may require AV junctional ablation when AV optimization is impossible in patients with a poor clinical response. Fusion with the spontaneous QRS complex may be acceptable on a trial basis to seek a better clinical response or with a short PR interval. Routine VV optimization is presently controversial but programming may prove beneficial in some patients with a suboptimal CRT response where no cause is found. It may partially compensate for less than optimal left ventricular (LV) lead position and may correct for heterogeneous ventricular activation including a prolonged LV latency interval and slow conduction (scarring) near the LV pacing site. VV timing is generally programmed using the aortic velocity-time integral, and long-term variations of the optimal value necessitate periodic re-evaluation.

Publication types

  • Review

MeSH terms

  • Cardiac Pacing, Artificial / methods*
  • Echocardiography / methods*
  • Heart Failure / diagnostic imaging*
  • Heart Failure / prevention & control*
  • Humans
  • Image Enhancement / methods
  • Outcome Assessment, Health Care / methods*
  • Quality Control
  • Treatment Outcome
  • Ultrasonography, Interventional / methods*