Sinus Preference Feature
Sinus Preference is intended to improve cardiac hemodynamics, primarily at lower rates, by providing preference to sinus activation of the heart over sensor-driven pacing. This occurs when the sinus rate and sensor-indicated rate are nearly the same. The feature permits a slower intrinsic escape rate by occasionally searching for the sinus rate below the sensor-indicated rate or when intrinsic atrial events are tracked (sinus breakthrough).
This feature can be found in some Medtronic Pacemakers. Please go to manuals.medtronic.com or consult with your local Medtronic representative regarding device models available in your geography.
Sinus Preference is available when the pacemaker is programmed to the DDDR mode and is nominally On.
Additional programming parameters include (nominal settings are shown in image below):
- Sinus Preference Zone – The maximum drop in rate from the sensor-indicated rate while searching for or tracking the sinus rate.
- Search Interval – The amount of time between sinus search operations.
To program this feature, go to Params -> Intrinsic Activation / AV Intervals.
- If Mode Switch is On, Sinus Preference is temporarily disabled when the pacemaker switches to the non-atrial tracking mode. It is enabled once the pacemaker returns to the atrial tracking mode.
- Atrial Preference Pacing and Sinus Preference cannot be enabled concurrently.
- Sinus Preference cannot be enabled if the programmed mode is any mode besides DDDR including AAIR<=>DDDR (MVP™).
Sinus Preference operation permits the sensor-driven pacing rate to gradually drop to a lower escape rate. If the sinus rate is not present at the Lower Escape Rate for eight paced beats, the rate is gradually raised back to the sensor-indicated pacing rate. The operation is repeated for the next scheduled time.
Sinus Preference operates in two modalities: Sinus Search operation and Sinus Breakthrough operation.
During Sinus Search operation, the pacemaker searches for a sinus rate that is slightly below the sensor-indicated rate. When the Search interval expires, the pacemaker gradually drops the pacing rate until the sinus rate is sensed or until the rate drops to the Sinus Preference Zone limit.
- If the sinus rate is sensed, ventricular rate is tracked to the sinus rate.
- If no sinus rate is present in the Sinus Preference Zone, the pacemaker paces at the Sinus Preference Zone limit for eight beats, whereupon rate is gradually increased to the sensor-indicated rate.
At the end of the Sinus Preference episode, the search interval is restarted and, once the interval expires, the sinus search operation is repeated.
During Sinus Breakthrough operation, the pacemaker tracks the sinus rate to a rate that is below the sensor-indicated rate. The pacemaker can track the sinus rate down to the Sinus Preference Zone limit, but never below the Lower Rate.
Once the sinus rate falls below the Sinus Preference Zone limit, the pacemaker paces at this rate for eight beats, whereupon, the rate is gradually increased to the sensor-indicated rate.
Note that even though the search interval does not start the sinus breakthrough operation, the search interval is reset once sinus breakthrough tracking ends.
- The possible clinical consequences of pacing the right atrium include: increased intra-atrial conduction times, a reduction in left atrial filling time, and reentrant atrial arrhythmias.1,2
- Atrial dyssynchrony may reduce cardiac output.3
- Reducing unnecessary atrial pacing may potentially improve device battery longevity.4
- Byrd CL, Schwartz SJ, Gonzales M, et al. DDD pacemakers maximize hemodynamic benefits and minimize complications in most patients. PACE. November 1988;11(11, Part II):1911-1916.33.
- Spencer WH III, Zhu DW, Markowitz T, Badruddin SM, Zoghbi WA. Atrial septal pacing: a method for pacing both atria simultaneously. PACE 1997;20(11):2739-2745.
- Katsivas A, Manolis AG, Lazaris E, Vassilopoulos C, Louvros N. Atrial septal pacing to synchronize atrial depolarization inpatients with delayed interatrial conduction. PACE. November 1998;21(11, Part II):2220-2225.
- Medtronic data on file. Longevity projections are based on a Medtronic Kappa™ 701, DDD 60. Atrial and ventricular outputs programmed to 2.5 V and 0.4 ms on a 500 ohm system.
Source: Medtronic Adapta™/Versa™/Sensia™ Reference Guide.