CRT and Optimizing Cardiac Function with Echocardiography

Anne Jacobson

doi:10.1177/155989771007009

Summary

Cardiac resynchronization therapy (CRT) devices are often used to treat heart failure and cardiac dysrhythmias. Optimization of CRT devices enriches cardiac health, as demonstrated by improved ejection fraction and NYHA functional class, as well as extended distance that is covered during the 6-minute hall walk. This article discusses various ways of optimizing CRT devices and how to make the most of imaging modalities, such as echocardiography.

Interventional Techniques & Devices
Cardiac Imaging Techniques Clinical Trials
Imaging Modalities

Cardiac resynchronization therapy (CRT) devices are often used to treat heart failure and cardiac dysrhythmias. Leads that are placed in the cardiac muscle create electrical pulses that stimulate coordinated contractions within the atrium, right ventricle, and left ventricle, which fosters optimal diastolic filling and systolic contraction. Optimization of CRT devices enriches cardiac health, as demonstrated by improved ejection fraction and NYHA functional class, as well as extended distance that is covered during the 6-minute hall walk. John R. Dylewski, MD, FACC, South Miami Heart Center, Miami, Florida, USA, discussed various ways of optimizing CRT devices and how to make the most of imaging modalities, such as echocardiography.

Atrioventricular (AV) delay may be optimized using 2-dimensional echocardiography to evaluate mitral regurgitation and septal wall motion. Ideally, AV delay should be the shortest possible to allow for maximal ventricular filling while reducing mitral regurgitation and increasing left ventricular function. However, if AV delay is too short, E/A wave diastasis may ensue, resulting in almost no atrial kick. The atrium contracts too late; so, the AV delay should be increased. Conversely, E/A wave fusion occurs when the AV delay is too long. Thus, an excess of atrial kick with little or no E wave occurs, and truncation of A wave may occur by premature closure of the mitral valve. AV optimization results in improved diastolic function.

Echo-driven V-V optimization improves systolic function and is also vital to the management of CRT devices. Using the parasternal long axis view of M-Mode echocardiographic imaging, the timing between septal and posterior wall contractions should be coordinated. When the ventricles are synchronized, V-V optimization has been achieved.

Optimal delays do change over time. Therefore, it is important to check timing, recalibrate rhythm, and ensure optimization regularly. Timing is everything, and cardiac rhythm synchronization can greatly influence the burden of disease.

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