INITIAL EXPERIENCE WITH A RATE-DROP PACEMAKER PROGRAM FOR NEUROCARDIOGENIC SYNCOPE.
Angas W. F. Hamer,
Cardiology Department, Box Hill Hospital, Box Hill, Vic.
Neurocardiogenic ("vasovagal") syncope has a bradycardic component that can be prevented by cardiac pacing. However, even dual chamber low rate AV sequential pacing may be unable to prevent hypotension from concurrent vasodilatation during an episode of syncope. This report is of an initial experience with pacemaker software programs that detect the onset of bradycardia and institute several minutes of high rate pacing to minimise hypotension.
Ten patients, (pts) aged 54-82 years, had a Medtronic THERA'® or KAPPA® pacemaker implanted for frequent recurrent syncope and/or presyncope; seven patients had failed to respond to up to 5 different medications previously. Their diagnosis was based on clinical history, negative tests for other causes of syncope, and a positive tilt table test (7 pts). The pacemakers were programmed to either DDD or DDI mode (low rate 60 ppm) with a rate drop detection set at 20-40 bpm. Triggered high rate pacing was for 3-5 mins at 110-120 ppm.
Follow up was for 3-15 (median 6) months. All patients continued to have multiple, characteristic rate drop episodes detected by the pacemaker during followup, indicative of a continuing syncopal predisposition. In five patients, syncopal episodes completely disappeared, with a marked symptomatic improvement overall. In the remaining 5, presyncope/syncope continued but with a noticeable reduction in frequency and severity, graded by the patients as a moderate but significant effect of pacing. No pacemaker related complications occurred. The conclusion was that pacemaker therapy with a rate drop program appears to be useful in many patients with severe, recurrent neurocardiogenic syncope, including those resistant to drug therapy.
