optimization of the AV delay in a dependent patient

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Tracing N° 1
Medtronic Devices: CRT Field: AV & VV delays optimization
Patient

74 years old man implanted with a triple chamber pacemaker Consulta CRT-P for idiopathic dilated cardiomyopathy with complete AV block ; Pacemaker interrogation 3 days post implant, 

Graph and trace

The first line correspond to an electrocardiographic derivation with superimposed markers (MA), The second line correspond to the bipolar atrial recording (EGM1), the tird line correspond to the bipolar right ventricular EGM (EGM3) and the fourth line to the distal (tip) LV / RV coil derivation (EGM2) ;

  1. The programmed paced AV delay is short (100ms);  atrial paced rhythm and biventricular pacing (AP-BV cycles) ; On the atrial EGM, we see that the ventricular depolarization occurs just in the middle of the atrial depolarization (at least for some atrial event);
  2. Identical AV delay;
  3. programming change (extension of the paced AV delay to 180 ms) ;
  4. the appearance of the ventricular EGM is not impacted by the change of programming; however, the ventricular depolarization occur now at the end of the atrial depolarization ; 
Comments

These tracings illustrate the specificity of the AV delay programming in a pacemaker dependent patient (complete atrioventricular block). For this type of patient, regardless of the programmed AV delay, the appearance of the stimulated QRS remains unchanged since no fusion with a potential spontaneous QRS occurs. This allows you to concentrate only on the chosen optimization parameter: the longest filling time with no abbreviation of the A wave, the importance of mitral regurgitation, the dP / dt max, the cardiac output ... Ideally, the optimal AV delay corresponds to the value that allows the best compromise between all these parameters. The analysis of the depolarization time is probably insufficient.

In this patient, the echocardiography showed a sharp amputation of the A wave by a premature mitral valve closure at the first illustrated paced AV delay (100 ms). With the second and longer AV delay (180 ms), the filling time was better with a dissociation of the A wave and the E wave and the absence of truncated A wave. The quality of the mitral filling pattern seemed reproducible. In contrast, high variations from cycle to cycle of the subaortic VTI signals were observed, making them not reproducible and therefore not interpretable.

 

Theoritical features / Basic concepts

  Basic concepts : AV delay and VV delay optimization AV delay optimization VV delay optimization LV pacing alone or biventricular pacing ? AdaptivCRT algorithm   AV DELAY AND VV DELAY OPTIMIZATION Biventricular resynchronization provides significant clinical benefit, a reverse remodeling with reduction of the cardiac volume, and a decrease in morbidity and mortality in heart failure patients with wide QRS. The main limitation of this therapy is that all studies found a significant percentage of patients that do not respond favorably to the resynchronization therapy. Different approaches have been proposed to reduce the percentage of non-responders. Once the patient is implanted, a sub-optimal adjustment of the CRT device can contribute to alter the quality of the response. The principle...