DDD Pacing with Rate Drop Response Function …

1 DDD Pacing with Rate Drop Response FunctionVersus DDI with Rate hysteresis Pacing forCardioinhihitory vasovagal SyncopeFABRIZIO AMMIRATI, FURIO COLIVICCHI, SALVATORE TOSCANO,CLAUDIO PANDOZI, MARIA TERESA LAUDADIO,* FRANCESCO DE SETA,*and MASSIMO SANTINIFrom the Department of Heart Disease, San Filippo Neri Hospital and *Medtronic Italia, Rome, ItalyAMMIRATI, F., ET AL.: DDD Pacing with Rate Drop Response Function Versus DDI with Rate HysteresisPacing for Cardioinhibitory vasovagal syncope . Background: The effectiveness of cardiac Pacing in pre-venting vasovagal syncope remains controversial. However, DDI Pacing with rate hysteresis has been re-ported to prevent the recurrence of cardioinhibitory vasovagal syncope in up to 35% of affected subjectsand to reduce the overall incidence of syncopal episodes in the others.

2 Recently, DDD Pacing with a newpromising rate drop Response Function (Medtronic Thera-I model 7960) has become available in clinicalpractice. Aim of the study: The aim of the present open trial was to test the effectiveness of this new pac-ing modality in patients with cardioinhibitory vasovagal syncope . Study population and methods: Thestudy population included 20 patients (12 males and 8 females; mean age 14 yrs) with recurrentsyncope (mean number of prior episode = , range 5-11) and cardioinhibitory responses during twohead-up tilt tests: the first diagnostic and the second during drug therapy with either ^-blockade or etile-phrine.

3 The study patients were randomized to receive either DDI Pacing with rate hysteresis (8 patients)or DDD Pacing with rate drop Response Function (11 patients). The head-up tilt test performed 1 month af-ter pacemaker implantation was positive in 3 of 12 patients (25%) with DDD Pacing with rate drop re-sponse Function and in 5 of 8 patients ( ) with DDI Pacing with rate hysteresis . The mean durationof follow-up was months. During follow-up no patients with a DDD pacemaker with rate dropresponse Function had syncope , while 3 of 8 patients with a DDI pacemaker with rate hysteresis had re-currence of syncope (P < ). Conclusions: These data suggest that DDD Pacing with rate drop responsefunction is effective in cardioinhibitory vasovagal syncope and may be preferable to DDI Pacing with ratehysteresis.

4 (PACE 1998; 21[Pt. 111:2178-2181) vasovagal syncope , pacemaker therapyIntroductionNeiu-ocardiogenic syncope represents a com-plex S3nidrome in which a specific treatment rarelyis warranted owing to the sporadic nature of thedisorder. However, in a small percentage of pa-tienfs vasovagal episodes present as a chronic re-curring disorder with a distiurbing impact on thequality of life. Moreover, in certain circumstancessyncope may he life-threatening or cause severe in-juries. Therefore a thorough clinical assessmentand proper selection of treatment is necessary insome cases of recurrent syncope .]

5 Since patientsAddress for reprints: Fabrizio Ammirati, , Department ofHeart Disease, S. Filippo Neri Hospital, Via A. Friggeri 95,00136 Rome, recurrent neurocardiogenic syncope often areresistant to medical treatment, permanent cardiacpacing has been repeatedly proposed as long-termtherapy.^"* When significant bradycardia is notedduring tilt-induced syncopal spells, cardiac pacingmay represent a valuable therapeutic option. Sev-eral studies have tested the effectiveness of pacingin ameliorating symptoms of vasovagal syncope inthe laboratory^"'' and in clinical settings.^'^ Cumu-lative data suggest that cardiac Pacing may signifi-cantly reduce symptoms, although the optimalpacing mode has not been clearly defined.

6 In par-ticular, single chamber WI Pacing is unlikely to beeffective,^"^ while dual chamber DDI Pacing withrate hysteresis (RH) is more promising.^ DDD pac-ing with a new rate drop Function (RDR) recently2178 November 1998, Part IIPACE, Vol. 21 DDD-RDR VS DDI-RH Pacing FOR vasovagal SYNGOPEhas become available in clinical practice.^'^" Tbeaim of this open clinical trial was to test tbe effec-tiveness of tbis new Pacing modality (DDD-RDR)compared to the best known Pacing tberapy (DDIwitb RH) in patients witb recurrent cardioin-bibitory vasovagal Population and MethodsTbe study population included 20 patients(12 males and 8 females; mean age years,range 27 to 81 years) witb recurrent unexplainedsyncope despite a complete diagnostic evaluation(mean number of syncopal events before tilt test-ing = ; range 5 to 11).

7 Nine (45%) patients badsuffered severe trauma from one or more addition, 5 male patients were engaged in po-tentially dangerous occupations (2 bus drivers, 2lorry drivers, 1 taxi driver). To be eligible for in-clusion in tbe study all patients bad to fulfill tbefollowing criteria: (1) a positive cardioinbibitoryresponse (VASIS type 2B)" to a first head-up tilttest performed according to the Westminster pro-tocoF^; (2) a positive cardioinhibitory Response toa second bead-up tilt test performed witbin 1montb of tbe first test using pbarmacological treat-ment witb eitber etilepbrine (50 mg/day; 7 pa-tients) or atenolol (100 mg/day; 13 patients).

8 Aftertbe second positive bead-up tilt test, tbe patientswere randomized to receive one of two types ofpermanent pacemaker. Twelve patients received aDDD pacemaker witb RDR Function (MedtronicThera-I model 7960, Medtronic, Inc. Minneapolis,MN, USA) and eight patients received a DDI pace-maker with RH programmed at 40/80 beats/min(Biotronik Pbysios TC 01, Biotronik, Lake Os-wego, OR, USA). One montb after pacemaker im-plantation all patients underwent a tbird head-uptilt test and were followed ProgrammingConstant cardiac Pacing is not necessary inpatients witb recurrent isolated vasovagal syn-cope, wbile a proper Pacing intervention shouldbe delivered for incipient syncopal episodes.

9 Con-sequently, tcjaveid inappropriate Pacing botbpacemakers were programmed witb a lower rate at40 beats/min and an AV delay of 300 ms, tberebyfavoring spontaneous cardiac RDR AlgorithmTbe RDR algoritbm offers tbe following pro-grammable parameters: (1) top rate (tbe beart ratefrom wbicb tbe pacemaker recognizes tbe onset ofdrop in beart rate); (2) bottom rate (tbe beart rate atwbicb tbe pacemaker recognizes tbat beart rate basfallen sufficiently to warrant Pacing intervention);(3) widtb beats (if tbe beart rate falls between topand bottom rates in fewer tban tbis number of beatspacing is triggered); (4) confirmation beats (tbebeats below tbe bottom rate necessary before tbeneed for Pacing is confirmed); (5) intervention rate( Pacing rate following confirmation); (6) interven-tion duration (tbe duration of Pacing before grad-ual return to intrinsic beart rate).

10 RDR ProgrammingBecause of tbe complexity of eacb pacemakerparameter, careful individual progranmiing is nec-essary. We believe tbat a critical assessment of theindividual Response to head-up tilt testing is re-quired to optimize the Pacing intervention duringan episode. Therefore, the RDR parameters wereprogrammed on the basis of the heart rate bebaviorduring bead-up tilt testing in all patients as follows:(1) tbe beart rate just before tbe onset of symptomswas used as tbe top rate; (2) tbe bottom rate was setat 20 beats/min above tbe beart rate at wbicb tbepatient lost consciousness, (3) tbe widtb beats wereprogrammed as tbe number of beats occurring be-tween top rate and bottom rate during tbe vasova-gal reflex induced by bead-up tilt testing, (4) toavoid inappropriate pacemaker interventions twoconfirmation beats were programmed.