[Optimized programming during cardiac resynchronization therapy]

Cardiac resynchronization (CRT) has evolved as a therapeutic add-on tool in patients with refractory heart failure. Additional pacing of the left ventricle leads to relevant clinical and hemodynamic improvement. Optimized programming of these pacing systems may modulate therapeutic efficacy. Optimal atrio-ventricular (AV) and ventriculo-ventricular (VV) delay programming is documented to increase invasively and non-invasively determined parameters of cardiac hemodynamics. In this manuscript different options for determining optimal AV and VV delay are discussed and a pragmatic approach to optimize CRT programming is detailed. VV delay needs to be optimized as a first step of programming. Different techniques may estimate the individual need for sequential ventricular pacing. Especially electrocardiographic criteria during right and left ventricular pacing may approximate the time-delay for pre-excitation. Delay between aortic and pulmonic valve ejection can be determined using Doppler echocardiography may identify patients who benefit from sequential pacing. Optimizing AV delay is a domain of Doppler echocardiography where using a simple formula the AV delay that produces the best diastolic resynchronization of left atrial contraction and left ventricular ejection can be calculated.Using the above mentioned techniques a pragmatic, easy and fast method for increasing CRT performance can be established. In cases of worsening heart failure or relevant changes of left ventricular dimensions adaptions (re-optimization) of VV and AV delay may be needed.