Heart Rhythm Devices Soori Sivakumaran BASc MEng MD PEng FRCPC
Medical Director, Heart Rhythm Device Clinic, Mazankowksi Alberta
Heart Institute Associate Clinical Professor of Medicine University
of Alberta in the ER
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Devices are common In Canada 2011 5200 new ICDs, 2076
replacement ICDs MAHI/U of A Hospital 2011/2012 210 new ICDs, 71
ICD generator changes 261 new pacemakers, 73 pacemaker generator
changes HRDC MAHI/U of A 1598 pacemaker patients, 1035 ICD patients
5647 patient clinic visits Chrysalis report 2011, MEDEC Alberta
Health Services
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ER Device Presentations Post-operative complications Symptoms
due to the device working properly Symptoms due to the device
working improperly Bystander for unrelated presentations May impact
care of primary presentation May suspect problem with device
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Pacemakers: Bradycardia Symptomatic bradycardia Sinus node
disease AV disease advanced second degree or third degree heart
block Asymptomatic high grade AV block Not PACs with block, Type 1
second degree (inc. 2:1) Syncope bifascicular block Chronotropic
incompetence No reversible cause (ie. Rx, vasovagal etc) Epstein
AE, DiMarco JP et al. Circulation. 2008;117:2820-2840.
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Contains a battery that provides the energy for sending
electrical impulses to the heart Houses the circuitry that controls
pacemaker operations Circuitry Battery The Pulse Generator: Image
www.medtronic.com
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Images www.medtronic.com Transvenous Leads Have Different
Fixation Mechanisms Passive fixation The tines become lodged in the
trabeculae (fibrous meshwork) of the heart Active Fixation The
helix (or screw) extends into the endocardial tissue Allows for
lead positioning anywhere in the heart s chamber
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Pulse generator: power source or battery Leads or wires Cathode
(negative electrode) Anode (positive electrode) Body tissue IPG
Lead Anode Cathode Pacemaker Components Combine with Body Tissue to
Form a Complete Circuit
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NBG Code I Chamber Paced II Chamber Sensed III Response to
Sensing IV Programmable Functions/Rate Modulation V Antitachy
Function(s) V: Ventricle T: Triggered P: Simple programmable P:
Pace A: Atrium I: Inhibited M: Multi- programmable S: Shock D: Dual
(A+V) D: Dual (T+I) C: Communicating D: Dual (P+S) O: None R: Rate
modulating O: None S: Single (A or V) S: Single (A or V) O:
None
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Automatic Implantable Cardioverter Defibrillators 24/7 cardiac
monitoring and intervention Treat VT/VF Anti-tachycardia pacing
(ATP) for VT Cardioversion/Defibrillation for VT/VF Treat
bradyarrhythmias Full pacing functions (single, dual) Treat heart
failure Biventricular pacing
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www.hrsonline.org
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Secondary Prevention Survivors of VT/VF arrest w/o reversible
cause ICDs associated with a mortality reduction of 27% 1 Patients
with inducible VT on EPS Syncope and ischemic heart disease Non
sustained VT and ischemic heart disease Syncope and dilated
cardiomyopathy Unfortunately most patients don t survive first
episode 1 AVID Investigators. N Engl J Med. 1997;337:1576-1583
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Consider Primary Prophylaxis AICD EF less than or equal 35%
Ischemic cardiomyopathy (CCS Class 1) more than 4 weeks post most
recent MI more than 3 months post revascularization Dilated
cardiomyopathy with Class II, III heart failure (CCS Class II a)
more than nine months after diagnosis Benefit modest with ARR
approximately 2%/year Other high risk conditions eg. Long QT, ARVC
etc.
Re-Entry Murgatroyd, Krahn et al. Handbook of Cardiac
Electrophysiology. 2002.
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Anti-Tachycardia Pacing Murgatroyd, Krahn et al. Handbook of
Cardiac Electrophysiology. 2002. Pain free way of terminating VT
Burst pacing faster than the VT rate More effective on slower VTs
Can accelerate VT
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Cardiac Resychronization Therapy Hare, NEJM 2002;346:1902-5
right ventricle right atrium coronary sinus
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Magnets and Devices Pacemakers Device paces at its predefined
magnet rate Asynchronous mode (DOO, VOO) ICDs Disables tachycardia
detection Does NOT affect pacing therapies
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Pacemaker Presentations Failing to capture Pacing spikes no
capture Failing to sense Pacing occurs where it shouldnt like on T
wave Failing to output Oversensing no pacing spikes because the
device sees a signals it thinks are coming from heart beats but
they are not!
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Pacing - Tachyardia Failure to mode switch tracking of atrial
fibrillation/flutter with rapid paced ventricular rate Medications
wont control the rate Pacemaker Mediated Tachycardia Retrograde
conduction to the atrium from a PVC starts a rapid pacing cycle via
the pacemaker
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Hysteresis
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The DAVID Study Adverse Effects of RV Pacing Objective To
compare the efficacy of dual chamber pacing with back-up VVI pacing
in patients with a standard ICD indication 506 patients randomized
to DDDR pacing at 70 bpm vs VVI back-up pacing at 40 bpm No
indication for bradycardia pacing Maximal tolerated medical therapy
JAMA. 2002;288(24):3115-3123
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Outcome: DAVID Trial The DAVID Trial Investigators, JAMA
2002;288:3115-3123.
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MVP Basic Operation DDD(R) Switch Ventricular support if loss
of A-V conduction is persistent Image www.medtronic.com
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Complex Pacing Algorithms Minimize RV Pacing Mode switching
algorithms AV delay extension algorithms Prevention of atrial
fibrillation Atrial overdrive / PAC suppression Rate smoothing in
persistent atrial fibrillation Pacing in ventricle may result in a
slower average ventricular rate
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Patient Shocks Normal function of the AICD Patient feels well
post shock(s) Leave message with AICD Clinic Scheduled assessment
within few days Patient feels unwell post shock(s) Go to nearest ER
Patient with an device/lead under a manufacturers advisory may
require urgent assessment also
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Inappropriate Shocks Shocks received for reasons other than
VT/VF Causes include: Sinus tachycardia Atrial fibrillation with a
rapid ventricular response Other supraventricular tachyarrhythmias
Lead Fracture External noise
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Complications Lead dislodgement 2.3% Early ICD system infection
1.9% Pneumothorax 0.6% Device malfunction 0.5% Serious bleeding
0.4% Venous thrombosis 0.2% Cardiac perforation 0.1% CCS/CHRS
Position Paper on Implantable Cardioverter Defibrillator (ICD) Use
in Canada
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Post-op Site Check
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Hematoma
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Post AICD Implant 12 months
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` Parsonnet V, Trivedi A. Circulation. 2000;102:1192.
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Lead Infection Clinical symptoms suggestive of systemic
infection and positive blood cultures warrant further evaluation
with TEE Strands and clot on leads can be a normal finding
Sometimes appearance can be highly suggestive of infection
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Leads Attached to Veins by Fibrotic Tissue
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Preventing Infections ECG Electrode on device site can cause
erosion Starting heparin or low molecular weight heparin will cause
a large hematoma Central lines provide a route for sepsis and lead
infection Sepsis from any source can settle on the device
leads
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Peri-Operative Device Management Device type and indication
Pacemaker dependence Surgery location Accessibility to device site
during procedure Canadian Cardiovascular Society/Canadian
Anesthesiologists/Canadian Heart Rhythm Society Joint Position
Statement on the Perioperative Management of Patients with
Implanted Pacemakers, Defibrillators and Neurostimulating Devices.
CJC 28(2012) 141-151.
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Reason for a device check Patient symptoms Shocks
Syncope/Significant presyncope Palpitations Also consider: SOBOE:
chronotropic incompetence, loss of BiV pacing Documented device
failure (on ECG) Patient lost to device follow-up
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Remember Settings/notes available from Device Clinic Presence
of patient in hospital is not an indication to check the device
Were here to help
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Conclusion
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Heart Rhythm Device Clinic Pacemaker Clinic Nurse run,
physician supervised 4 weeks, 3 months, 6 months, 12 months Assess
patient symptoms Lead performance Battery Status Programming
changes ICD Clinics EP Physician attended Anti-arrhythmic
medications checked Episodes recorded by the device reviewed