1. Heart Rhythm Devices in the ER
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

2. Devices are common In Canada 2011 MAHI/U of A Hospital 2011/2012
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

3. 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

4. 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:

5. The Pulse Generator:
Contains a battery that provides the energy for sending electrical impulses to the heart
Houses the circuitry that controls pacemaker operations
Circuitry
Lithium-iodine is the most commonly used power source for today’s pacemakers. Microprocessors (both ROM and RAM) control sensing, output, telemetry, and diagnostic circuits.
Battery
Image

6. 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
Images

7. Pacemaker Components Combine with Body Tissue to Form a Complete Circuit
Pulse generator: power source or battery
Leads or wires
Cathode (negative electrode)
Anode (positive electrode)
Body tissue
Lead
IPG
In a bipolar system, body tissue is part of the circuit only in the sense that it affects impedance (at the electrode-tissue interface). In a unipolar system, contact with body tissue is essential to ground the IPG and allow pacing to occur.
Anode
Cathode

8. NBG Code P: Simple programmable V: Ventricle V: Ventricle T: Triggered
Chamber
Paced II
Sensed
III
Response
to Sensing IV
Programmable
Functions/Rate
Modulation V
Antitachy
Function(s)
P: Simple
programmable
V: Ventricle
V: Ventricle
T: Triggered
P: Pace
M: Multi-
programmable
A: Atrium
A: Atrium
I: Inhibited
S: Shock
D: Dual (A+V)
D: Dual (A+V)
D: Dual (T+I)
C: Communicating
D: Dual (P+S)
The first letter refers to the chamber(s) being paced
The second letter refers to the chamber(s) being sensed
The third letter refers to the pacemaker’s response to a sensed event:
T = Triggered D = Dual (inhibited and triggered*)
I = Inhibited O = No response
*In a single chamber mode, “triggered” means that when an intrinsic event is sensed, a pace is triggered immediately thereafter. In a dual chamber mode, “triggered” means that a sensed atrial event will initiate (trigger) an A-V delay.
The fourth letter denotes the pacemaker’s programmability and whether it is capable of rate response:
P = Simple Programmable (rate and/or output)
M = Multiprogrammable (rate, output, sensitivity, etc.)
C = Communicating (pacemaker can send/receive information to/from the programmer)
R = Rate Modulation
O = None
Note that this sequence is hierarchical. In other words, it is assumed that if a pacemaker has rate modulation capabilities, “R”, that it also can communicate, “C”.
The fifth letter represents the pacemaker’s antitachycardia functions:
P = Pace D = Dual (pace and shock available)
S = Shock O = None
You may want to test the audience by having them describe different pacing modes. More modes and ECG strips are found in Module 2.
O: None
O: None
O: None
R: Rate modulating
O: None
S: Single
(A or V)
S: Single
(A or V)
O: None

9. 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

11. 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
1AVID Investigators. N Engl J Med. 1997;337:

12. 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.

14. Discrimination: SVT vs VT
Heart Rate
A-V relationship
Onset
Stability
Morphology

15. Morphology Analysis

16. Re-Entry
Murgatroyd, Krahn et al. Handbook of Cardiac Electrophysiology

17. Anti-Tachycardia Pacing
Pain free way of terminating VT
Burst pacing faster than the VT rate
More effective on slower VTs
Can accelerate VT
Murgatroyd, Krahn et al. Handbook of Cardiac Electrophysiology

18. Cardiac Resychronization Therapy
right
atrium
coronary
sinus
right
ventricle
Hare, NEJM 2002;346:1902-5

21. Magnets and Devices Pacemakers
Device paces at its predefined magnet rate
Asynchronous mode (DOO, VOO)
ICDs
Disables tachycardia detection
Does NOT affect pacing therapies

22. Pacemaker Presentations
Failing to capture
Pacing spikes – no capture
Failing to sense
Pacing occurs where it shouldn’t – 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!

23. Pacing - Tachyardia
Failure to mode switch – tracking of atrial fibrillation/flutter with rapid paced ventricular rate
Medications won’t control the rate
Pacemaker Mediated Tachycardia
Retrograde conduction to the atrium from a PVC starts a rapid pacing cycle via the pacemaker

24. Hysteresis

25. 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
Clinical motivations by the device industry to develop unique algorithms (Search AV, AV Hysteresis, etc.) and/or pacing modes (AAISafeR etc.) to actively manage ventricular pacing were brought about by the well-understood relationship between the electrical-mechanical synchrony required by the heart to maintain optimal hemodynamic performance. Specifically, the atrial chamber contractions provide an important filling contribution to ventricular output. Coordinated pumping between the left and right ventricles is necessary to achieve adequate ejection fractions. When this AV synchrony and ventricular synchronization is lost, patients may suffer from poor systolic function and low cardiac output.
JAMA. 2002;288(24):

26. Outcome: DAVID Trial
The DAVID Trial Investigators, JAMA 2002;288:

27. MVP Basic Operation
DDD(R) Switch Figure: If your patient develops persistent loss of conduction, the device will automatically switch to DDD(R) operation, but continue to periodically look for restored conduction.
Details on this switch provided in subsequent slides.
DDD(R) Switch Ventricular support if loss of A-V conduction is persistent
Image

28. 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

29. 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 manufacturer’s advisory may require urgent assessment also

30. 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

31. 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

32. Post-op Site Check

33. Hematoma

34. Post AICD Implant – 12 months

35. `
Parsonnet V, Trivedi A. Circulation ;102:1192.

36. 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

37. Leads Attached to Veins by Fibrotic Tissue

38. 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

39. 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)

40. 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

41. Remember Settings/notes available from Device Clinic
Presence of patient in hospital is not an indication to check the device
We’re here to help

42. Conclusion ≠

43. 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

44. CRT requires wide complex ECG and Class II+ CHF