New developments for upper rate response in DDD pacing

Although widely accepted as an effective method of dealing with rapid atrial rates in a DDD pacemaker, Wenckebach-type and multiblock-type upper rate behaviors may exacerbate pacemaker-mediated tachycardia through AV dissociation. In addition, pathologic atrial rates (e.g., atrial fibrillation, atrial flutter, automatic atrial tachycardia, etc.) frequently result in ventricular pacing at inappropriately high rates. New, more sophisticated algorithms available in today's microprocessor-based DDD pacing systems provide the capability to discriminate successfully a normal atrial rate response to exercise from a pathologic atrial rate. These and other improved capabilities allow the clinician to provide safe rate-responsive pacing to patients in whom rate-responsive pacing was previously contraindicated.