Table 2. Summary of programming recommendations.
| Parameter | Setting | Comment |
|---|---|---|
| Pacing mode | VVI(R) | Single-chamber system |
| AAI(R) | In case of single-chamber system with low detection amplitude of the His lead - allows higher sensitivity setting than with VVI(R). | |
| DDD(R) | Do not programme long AVI (e.g. 200ms) if the His lead is connected to the A port (due to risk of His pacing on the T-wave in case of intermittent loss of His lead capture). | |
| AAI(R)/DDD(R)* ADI(R)/DDD(R) |
Avoid programming if His lead connected to the A port (cf comment above), or if pacing from the LV port is desired (as only RV pacing is delivered in these modes. | |
| DVI(R) | May be programmed if the His lead is connected to the A port, but results in pacing above the upper sensor-driven rate due to ventricular-based timing. | |
| DDI(R) | With the His lead in the A port, avoid programming long AVI (c.f. comment on DDD). With the His lead in the A port, results in pacing above the upper sensor-driven rate due to V-based timing. | |
| Pacing rates | According to clinical requirement | |
| AVI | ||
| - His lead in atrial port | Delay depends on requirement | If V backup pacing is desired, programme paced AVI> Stim His-VS interval (but ≤180ms cf. comment on DDD). If His+RV/LV pacing is desired, programme a short AVI (shortest is 30ms*). |
| - His lead in RV/LV port | Usual AVI – HV interval (or stimulus-QRS onset) | AV hysteresis may be programmed if V pacing needs to be avoided. |
| Sensing vector | Bipolar | Unipolar may be tried if low sensing amplitude or if issues with P-wave oversensing. |
| Sensitivity | ||
| - His lead in A port | Lowest possible (e.g. 4mV) | Program lowest sensitivity to avoid issues with oversensing of A or His potentials (V is sensed by RV lead). |
| - His lead in RV port | As usual practice | Ensure no oversensing of A or His potentials. Consider automatic sensing threshold in case of low R-waves. |
| - His lead in LV port | Not available or inactivate | V sensing by RV lead. |
| Pacing vector | Consider unipolar or extended bipolar (if available). | Capture thresholds are usually lower than with bipolar vector, and pacing spike is visible (avoids confusion with intrinsic rhythm on ECG). Trade-off is lower impedance compared to bipolar (i.e. higher current drain). |
| Capture management algorithms | Off or monitor | Rarely yields accurate measurements. Must be inactivated in Medtronic CRT devices if configuration is His in LV port and RV output is subthreshold (as backup pacing during atrial, RV and LV automatic threshold tests is RV only at the programmed output*). Default setting is “adaptive”.* The same also applies to Boston Scientific CRT devices for the LV automatic capture threshold tests. |
| Ventricular safety pacing | On or off (non-programmable in some devices | Consider turning off in case of His lead in A port, to avoid unnecessary V pacing (and inform of loss of His lead capture -corresponding to the percentage of AP-VP). However, presence of AV crosstalk should be tested first with “worst case” scenario. |
| AdaptivCRT* | “Off” | Will yield suboptimal intervals. Nominal setting is “Adaptive BiV and LV”. |
| VV delay | His lead first. Delay dependant on requirement. | If His-only pacing is desired (and backup pacing by the ventricular lead), programme to maximum delay (with His first). In case of His-optimized CRT, programme the VV delay to optimize fusion with V lead. |
| EffectivCRT diagnostic* | Non-programmable | Feature designed to indicate LV capture. If His lead in LV port, selective His capture may be indicated by “ineffective” pacing. |
| EffectivCRT during AF* | “Off” if His lead in LV port | Feature designed to increase pacing rate during AF if “ineffective” LV pacing is diagnosed (even in case of RV pacing), which may be the case with selective His capture. Default is “on”. |
| Conducted AF response | “On” | Algorithm increases pacing rate in case of V sensing during AF, to promote CRT. Will not be activated if the His lead is in the A port. Default is “on”. |
| Ventricular sense response | “Off” | VVT pacing designed to resynchronize conducted beats (e.g. in AF). Is ineffective for HBP and will result in unnecessary battery drain. Default is “on”. |
| Non-competitive atrial pacing | “On” | Algorithm designed to avoid pacing shortly after an A refractory sensed event. Does not affect HBP. Nominal is “on”. |
| PVC response | “On” | Post PVC PVARP extension designed to avoid endless loop tachycardia. Does not affect HBP. Nominal is “on”. |
| Ventricular refractory period | >200ms (usually by default) | If His is connected to the LV port with pacing only from the LV channel, RV double-counting may occur if the Stim His to RVS interval > ventricular blanking. |
| ICD rhythm discrimination algorithms | Inactivate dual-chamber algorithms (e.g. PR logic) if His lead in atrial port! | Use single chamber discriminators instead (sudden onset, stability, morphology discrimination). Inactivate rhythm discriminators if the patient is in complete AV block. |
A: atrial; AF: atrial fibrillation; AV: atrioventricular; AVI: atrioventricular interval; CRT: cardiac resynchronization therapy; DHBP: direct His bundle pacing; ICD: implantable cardioverter defibrillator; LV: left ventricular; RV:right ventricular; RVS: right ventricular sense; Stim: stimulation; V: ventricle; VS: ventricular sense;
*
applicable to current Medtronic devices