ventricle in 59 and the atrium in 3 cases. Forty-one (66.1%) patients hadpermanent device implantation during index hospitalization and 3 (4.8%)were transferred to referring facility for future re-implantation. In 9(14.5%) cases, permanent pacing was subsequently no longer indicated,and 9 (14.5%) patients died prior to permanent device placement; no deathswere due to arrhythmia. There were no procedural complications. MeanSPP implant duration was 10.0�7.7 (1 to 35) days during mean hospital-ization of 23.3�18.8 days. The 41 permanent devices were: DDDR PCM(n�27, 65.9%), VVIR PCM (n�4, 9.8%), DDDR ICD (n�7, 17.1%),VVIR ICD (n�2, 4.9%), and CRT-D (n�1, 2.4%).Conclusion: A transvenous active-fixation lead with a re-sterilized externalpacemaker generator is a safe and feasible approach to temporary pacing.Such “semi-permanent” pacing systems may be particularly useful whentemporary pacing may be required for an extended period.

AB22-2

EFFECT OF CPAP THERAPY ON ATRIAL FIBRILLATIONBURDEN IN PACEMAKER PATIENTS WITH HEART FAILUREAND CHEYNE-STOKES BREATHINGOmid Souresrafil, MD, PhD and Peter Nickolls, MBBS.University of Sydney, SCH Cardiac Hospice, Minneapolis,MN and University of Sydney, Australia.

Background: Atrial fibrillation (AF) is the most common arrhythmia andaccounts to substantial morbidity . Despite a number of therapies available topatients the management of AF remains a challenge. Continuous positivepressure therapy (CPAP) has proven an effective tool in the management ofsleep disordered breathing in patients with advance heart failure. In this studythe effects of CPAP therapy on AF burden is examined in patients withCheyne-Stokes breathing (CSB) and heart failure and a history of AF.Methods: Twenty patients implanted with a dual chamber implantablepulse generator (IPG) and advanced heart failure, Cheyne-Stokes Breathing(CSB), and at least three episodes of documented history of AF (fromdevice memory) received CPAP therapy for a period of six months. Thenumber of Apnea-Hypopneas per hour (apnea-hypopnea index [AHI]) andminimal oxygen saturation (SAO2min) were qualified by cardiorespiratorypolygraphy. All patients showed CSA (AHI�5/h) and had their sleepquality assessed by the Pittsburgh Sleep Quality Index (PSQI).Results: Figure one shows the monthly and the mean (red) amount ofmonthly AF pre and post CPAP therapy. The mean AF burden was reducedfrom 62.3� 31 hours/month prior to receiving CPAP therapy) to 14.9� 7hours/month (post CPAP therapy. This correlated to a mean reduction ofright ventricular pacing percentage from 90�10 % (pre CPAP) to 13.3 �3(3 Months post CPAP) (figure 2).Conclusions: CPAP therapy reduces the amount of AF burden in heartfailure patients, Cheyne-stokes breathing with a history of AF.

AB22-3

DO INDUCTION COOKTOPS INTERFERE WITH CARDIACPACEMAKERS?Werner E. Irnich, PhD and Alan D. Bernstein, ScD.University Hospital, Giessen, Germany and Newark BethIsrael Medical Center, Newark, NJ.

Aims: In induction cooktops (IC), coils produce magnetic fields that induceeddy currents in ferromagnetic bottoms of pots or pans, thereby heatingthem. Electromagnetic interference (EMI) with pacemaker (PM) sensingcan be produced by voltages induced (VI) directly by induction or indi-rectly by leakage currents. A worst-case PM-patient model (PPM) repre-senting left-sided implantation of a unipolar PM was used for measurementof these VI, to judge whether IC could interfere with PMs.Material and Methods: 11 ICs were tested. Using the PPM, VI due to EMIwere measured. The PM sensitivity with respect to a 24-kHz voltage,amplitude-modulated at 100 Hz, was investigated in 244 PMs. The currentpassing through the body of a grounded patient touching a pot was deter-mined by measuring VI from hand to hand and between electrodes placedon the thorax to simulate an implanted unipolar PM system.Results: If the pot is positioned concentrically, the smallest pot producedthe largest stray field, but the VI always remained below the critical valueof 100 mV. With large, eccentrically positioned pots, VI were up to 800mV. VI could always be reduced to 60 mV or less by maintaining adistance of 35 cm between the IC and PPM. The most sensitive PM reactedat 90.3 mV. Due to leakage current, about 2% of the voltage between potand ground is estimated to appear across the PM’s input.Discussion: PM patients are at risk from EMI of IC if the implant isunipolar and left-sided, if they stand as close as possible to the IC, and ifthe pot is eccentrically positioned. Unipolar PMs can sense EMI generatedby leakage currents if the patient touches the pot for a substantial period oftime. The most likely response to EMI is switching to an asynchronousEMI mode. Patients with unipolar PMs are at risk only if they are notPM-dependent.

AB22-4

IMPEDANCE MEASUREMENTS ON HUMAN FETAL SKINEvgueni Fayn, MD, Daniel H. Zavitz, Howard A. Chou, PhD,Betina F. Cuneo, MD, Emine Kubra Dindar, Terence Harper,MD, Jack Garon, MD, David Lipson, Boris M. Petrikovsky,MD, PhD and Marc Ovadia, MD. University of Illinois andMichael Reese Hospital, Chicago, IL, The Heart Institute forChildren, Rush-Presbyterian Medical Center, Chicago, IL,Mount Sinai Hospital and Medical Center, Chicago, IL,Cornell University, Ithaca, NY and Nassau UniversityMedical Center, East Meadow, NY.

The monolithic fetal pacemaker is a unipolar pacemaker for pacing the fetalheart with the anode external to the fetus’ body, in amniotic fluid. In thiselectrode arrangement current passes through fetal skin in the pacing circuit.Cutaneous impedance reported for adult skin is not relevant because matureskin includes dehydrated layers and a hydrophobic (oily) phase. In contrast,fetal skin (a developing tissue bathed in amniotic fluid) may have a largeraqueous conductive component. In these experiments we measured AC im-pedance with determination equivalent circuit and use of broadband imped-ance spectroscopy to derive the Nyquist (Complex impedance) plot.Methods: With an IRB approved protocol human tissue was collected fromunselected human fetuses. Full thickness chest wall samples were studiedin 3 electrode potentiostatic configuration. AC current was applied (18Hzto �400kHz) with AD 744 single op-amp current/voltage converter, withdigital signal acquisition at 100MS/s. This allowed derivation of theNyquist plot and deduction of equivalent circuit.Results. 82 determinations of complex impedance were made on 8 sam-ples. Impedance plots showed real axis intercept of 220 � 43 � (min100�, max 200� with intraadipose electrode). A diffusional impedancewas present in all interfaces consistent with consistent with ionic conduc-tion and semisolid matrix. In at least one case 2 discrete elements were

S43Session 21

present. The Randles’ plot (|Z| vs. 1/√�) differential coefficient was 15614�.s1/2 in a single superior experiment where this was able to be determined.The underlying equivalent circuit is a bulk resistance in series with aYARC-class diffusional element.Conclusion Human fetal skin is a well-behaved circuit element with apredictable equivalent circuit and aggregate resistance for pacing. Thissupports the practicability of the monolithic fetal pacemaker. Support:National Institute of Health NIH HHS 1R43 HL 67520-01.

AB22-5

CHRONIC THERAPY WITH NON-EXCITATORY CARDIACCONTRACTILITY MODULATION ELECTRIC SIGNALS IMPROVESLEFT VENTRICULAR FUNCTION, REDUCES MYOCARDIALOXYGEN CONSUMPTION AND INCREASES MYOCARDIALMECHANICAL EFFICIENCY*Hani N. Sabbah, PhD, Makoto Imai, MD, Sharad Rastogi,MD, Naveen Sharma, PhD, Margaret P. Chandler, PhD,*Walid Haddad, PhD, *Yuval Mika, PhD and *William C.Stanley, PhD. Henry Ford Health System, Detroit, MI, CaseWestern Reserve University, Cleveland, OH and ImpulseDynamics, Mount Laurel, NJ.

Background: In dogs with heart failure (HF), left ventricular (LV) ejectionfraction (EF) increases during acute (2-4 hours) therapy with non-excita-tory cardiac contractility modulation (CCM) electric signals delivered tothe cardiac muscle during the absolute refractory period. The chroniceffects of CCM therapy, however, are not known and were examined inthis study.Methods: Studies were performed in 14 dogs with multiple sequentialintracoronary microembolization-induced HF. All dogs were implantedwith CCM leads and generators (OPTIMIZERTM-II, Impulse DynamicsUSA). CCM leads, one each, were fixed to the right ventricular anterior andposterior mid-septal grooves. A third sensing lead was positioned in theright atrium. Dogs were randomized to 3 months of no therapy (Sham-Controls, n�7) or to 3 months of CCM monotherapy (CCM-Treated,n�7). The CCM therapy regimen was 5 hours/day based on a duty cycleof one hour ON (CCM signal � 7.73 volts) and 3 hours and 48 minutesOFF. LV EF, end-systolic (ESV) and end-diastolic (EDV) volumes, myo-cardial oxygen consumption (MVO2), and myocardial mechanical effi-ciency (EFF) were measured before (PRE) and 3 months after initiatingtherapy (POST).Results: The results are shown in the table. In Sham-Controls, LV EF andEFF decreased while EDV, ESV, and MVO2 increased. In contrast, CCMtherapy increased LV EF and EFF and reduced EDV, ESV, and MVO2.Conclusion: In dogs with HF, chronic CCM therapy leads to markedimprovement in LV function that is associated with reduced MVO2 andincreased myocardial EFF all of which are desirable features of therapiestargeted to the treatment of HF.

AB22-6

LONG-TERM MONITORING OF SLEEP APNEA USING ANIMPLANTED DEVICE*Christoph Scharf, MD, *Sameh Sowelam, PhD, *Yong K.Cho, PhD, *Ulla Strobel, *Mark Erickson, BS, *TobyMarkowitz, BS and *Konrad Bloch, MD. University Hospitalof Zurich, Zurich, Switzerland and Medtronic, Inc.,Minneapolis, MN.

Background: Patients with cardiovascular disease are at high-risk for sleeprelated respiratory disorders. Untreated sleep apnea in the pacemaker (PM)population has recently gained attention of researchers. We investigated aPM-based algorithm to detect sleep apnea syndrome based on sensingminute ventilation (MV). Also, nightly variability of sleep apnea status wasassessed through ambulatory monitoring during 12 consecutive nights.Methods: 9 Patients (70 � 7y, 6 m) with a Medtronic Kappa 400 PMunderwent an overnight sleep study via polysomnography (PSG). Simul-taneously, the PM automatically measured sleep-disordered breathing(PMSDB) in real-time using MV. Data were stored in PM memory. A sleepphysician, blinded to the PM memory, analyzed the PSG according tostandard criteria and reported apnea-hypopnea index (AHI). PMSDB per-formance was compared to AHI. PMSDB was monitored and stored for 11subsequent nights while ambulatory.Results: PMSDB and AHI for the first night correlated significantly (r �0.9, p � 0.001, AHI � 0.23 * PMSDB). AHI of 15 is an often-used clinicalthreshold for initiation of sleep apnea therapy. 0.23 * PMSDB correctlypredicted AHI to be above or below 15 in all but one patient. PMSDB didnot significantly differ night to night (repeated measures ANOVA, p �0.97) and did not affect prediction of AHI above or below 15.Conclusion: PM-based sleep apnea screening is feasible and may be usefulin monitoring of night-to-night variability.

ABSTRACT SESSION 23: PEDIATRIC/ADULT CONGENITAL HEARTDISEASE I: Pediatric ElectrophysiologyThursday, May 5, 20054:30 p.m.–6:00 p.m.

AB23-1

PHENOTYPIC CHARACTERIZATION OF TIMOTHY SYNDROME -A COMPLEX CARDIAC AND MULTISYSTEM DISORDERRaffaella Bloise, MD, Katherine W. Timothy, BS, CarloNapolitano, MD, PhD, Igor Splawski, BS, Peter J. Schwartz,MD, Mark T. Keating, MD and Silvia G. Priori, MD, PhD.IRCCS, Fondazione Salvatore Maugeri, Pavia, Italy,University of Utah, Salt Lake City, UT, IRCCS FondazioneSalvatore Maugeri, Pavia, Italy, Children’s Hospital,Harvard Medical School, Boston, MA, University of Pavia,Pavia, Italy and IRCCS Fondazione Salvatore Maugeri -University of Pavia, Pavia, Italy.

Timothy syndrome (TS) is a rare variant of Long QT Syndrome (LQT8).We have recently reported a mutation in the cardiac voltage-gated calciumchannel (Cav1.2) in several TS patients (pts). However, the clinical fea-tures and genotype-phenotype correlation of TS remain poorly investi-gated. Here, we report the phenotypic characterization of the largest seriesof TS patients studied so far. Twenty children with TS have been thor-

S44 Heart Rhythm, Vol 2, No 5, May Supplement 2005