Pacemaker and Defibrillator

Troubleshooting

Jeffrey L. Williams, MD, MS, FACC, FHRS

Director, Invasive Cardiac Electrophysiology

Heart Rhythm Center

Lebanon Cardiology Associates

The Good Samaritan Hospital

Disclosures

• None

Objectives

• Be able to understand pacemaker and

defibrillator normal function and

troubleshoot common abnormal

conditions.

Pacemaker and ICD Topics for Boards

• Passing Score: ~65—70% correct is a pass, very few get

>90% correct. 80-85% first time pass rate

• Topics on EP Boards:

– Basic EP and Pharmacology: 5%

– Noninvasive Diagnosis and Treatment: 15%

– Invasive Diagnosis and Treatment: 42%

– Devices: 18%

– Clinical Syndromes: 7%

• Topics on General Cardiology Boards

– 13% Arrhythmias with up to 35% of these device related.

• Content not proportional to prevalence

Today’s Outline

• Pacing Functions and Timing Cycles

• Failure to Pace

• Loss of Capture

• Oversensing

• Undersensing

• Defibrillation Threshold Testing

• Arrhythmia Classification

• Sample Board Questions

Basics of Device Troubleshooting

• Use all the available information.

• Interrogate devices during your training.

• Look at the CXR’s.

Surface

EGM

Ventricular

EGM

Atrial

EGM

Markers

Pacemaker Function Codes ICHD Code

Position

Category

Letters Used

Manufac- turer’s Designation Only

I II III IV V

Chamber(s) Paced

Chamber(s) Sensed

Mode of Response(s)

Programmable Functions

Special Tachy- arrhythmia Functions

V- Ventricle A- Atrium D- Double O- None

V- Ventricle A- Atrium D- Double

T- Triggered I Inhibited D- Double O- None R- Reverse

P- Programmable rate and/or output

M- Multi- Programmable

C- Communicating O- None

B- Burst N- Normal Rate

Competition

S- Scanning E- External

S- Single Chamber

S- Single Chamber

, Comma Optional Here * Atrial Triggered & Ventricular Inhibited

Pacing Mode Selection

• AV block should have ventricular pacing support

• Sinus Node Dysfunction – atria should be supported with rate response.

• Neurocardiogenic syncope should have ―rate-drop‖ response activated.

• Atrial tachyarrhythmias need mode switching (atrial pacing paradigms likely not on boards).

Transitions of DDD Timing

Event Response

AV Interval Times Out Pace V, Begin VAI

VA Interval Times Out Pace A, Begin AVI

V sense during AVI Begin VA, No Pacing

V sense during VAI Restart VA, No Pacing

A sense during VAI Begin AVI, No Pacing

Timing Cycles

• Refractory Period: Sensed events are ignored for timing purposes.

• Blanking Period: Sensing amplifier is off and no sensing occurs.

• Maximum Tracking Rate in DDD

– TARP = AVI + PVARP

– Total Atrial Refractory Period (TARP), AV Interval (AVI), Post-Ventricular Atrial Refractory Period.

Pacemaker Timing Cycles • DDD, max track 100 ppm, AV delay 150

ms, PVARP 250 ms

Board Question #1

• Which of the following defines the

maximum tracking rate in DDD mode?

1. PVARP

2. VRP + AVI

3. TARP

4. AVI + Blanking Period

5. TARP - VRP

Troubleshooting

• Additional leads

• Magnet

• Manipulation of

pacemaker, pocket,

and leads.

• Isometric maneuvers

• CXR

• Exercise testing

– We had patient with

changing morphology

during exertion.

• Device reps and field

engineers.

Cheat Sheet

Voltage

Threshold

Current

Threshold

Lead Impedance

Wire Fracture High High/Nml/Low High

Insulation Break High/Nml/Low High Low

Lead

Dislodgement

High High Nml

Exit Block High High Nml

Pacemaker Syndrome:

Clinical Presentation

Pacemaker Syndrome

• Symptoms: malaise, weakness, cannon A

waves, CP, cough, confusion, syncope.

• Symptoms due to loss of AV synchrony.

• Most common with VVI or VVIR.

• May occur with any pacing mode if AV

synchrony lost.

Board Question 2

Patient complains of dizziness when running to his car the night prior to your

office visit. The rhythm strip is obtained during an treadmill exercise test.

The device parameters are: DDD, mode-switch detection rate 175bpm,

upper rate limit 150bpm, sensed AV interval 200msec, PVARP 400msec.

This EKG demonstrates:

A. Mode-switching

B. Rate-drop response

C. Rate-smoothing

D. Pacemaker-induced 2:1 block

E. None of the above

- Taken from Nacarelli et al, ACC EPSAPII.

Board Question 2 (Cont’d)

• The max tracking rate is 100bpm defined by TARP (AVI+PVARP=600ms).

• When spontaneous P wave rate exceeds max tracking rate of 100,

alternative P waves fall within PVARP, and are not responded to, creating a

2:1 AV block.

• Mode-switching not present since atrial rate does not exceed 175bpm; in

addition, PV intervals are the same during slower V pacing, suggesting VVI

pacing not present.

• Rate-drop response is not present, since this feature requires an abrupt

drop in spontaneous P wave rate for activation.

• Rate smoothing not present, since this strip shows an abrupt reduction in

paced ventricular rate rather than a smoothed one.. - Taken from Nacarelli et al, ACC EPSAPII.

Common Pacemaker Mediated Tachycardia

• Surface, atrial, and

ventricular EGMs

shown.

• The intracardiac

markers indicate that

the retrograde P

waves occur 280

milliseconds after the

ventricular-paced

beats.

• Occurs at

programmed upper

rate limit.

• Treatment is to

prolong PVARP.

Surface EGM

Ventricular EGM

Atrial EGM

Uncommon Endless Loop Tachycardia

• Repetitive Non-Reentrant Ventriculo-Atrial Synchrony

• Form of endless loop tachycardia (functional atrial non-capture with retrograde ―P‖ occurring in

PVARP

• Unlike the pacemaker mediated endless loop tachycardia, RNRVAS does not occur at the

programmed upper rate interval.

• The retrograde activation of the atria occurs within the PVARP so that it is not sensed by the

atrial circuit of the pacemaker (functional undersensing). Though it is not sensed by the atrial

circuit, it makes the atria refractory to the subsequent atrial paced output (functional loss of

capture). The ventricular output is delivered by the device at the end of the programmed AV

delay. {Johnson Francis, Indian Pacing Electrophysiol J. 2010; 10(5): 203–204.}

Automatic Mode Switching (AMS)

• AMS turns off atrial tracking in the presence of intrinsic atrial activity above a programmable atrial rate cutoff

• This stops rapid ventricular pacing in response to high-rate atrial activity

• AMS can cause a sudden rate decrease as atrial tracking in DDD at 140 ppm mode switches and becomes DDI at 70 ppm—in one cycle – Programmable AMS base rate allows an interim mode-switch rate to go

into effect—higher than the base rate

– Eliminates uncomfortable abrupt rate transitions

• Set atrial rate cutoff at which automatic mode switching (AMS) goes into effect – Program it to a value at least 20 bpm above the Maximum Tracking

Rate and/or Maximum Sensor Rate

• Set atrial rate cutoff high enough to accommodate: – Patient’s lifestyle and activity level

– Presence of sinus tachycardia

Automatic Mode Switching

- Taken from St. Jude Medical

Hysteresis

• Programming of hysteresis permits prolongation of the first pacemaker escape interval after a sensed event.

• A pacemaker programmed at a cycle length of 1000 milliseconds (60 bpm) and a hysteresis of 1200 milliseconds (50bpm) allows 200 milliseconds more for another sensed QRS complex.

• If another QRS complex is not recognized, then the pacemaker continuously stimulates the heart at the programmed rate of 60bpm, an escape interval of 1000 milliseconds, until a sensed event restarts the cycle.

• The advantage of hysteresis in a single chamber pacing mode is the ability to maintain spontaneous AV synchrony as long as possible

Hysteresis

Cardiac Pacing and ICDs, 5th Edition, Kenneth A. Ellenbogen, MD, Mark A. Wood, MD

p. 291.

Board Question 3

A 68 yo woman had a VVI pacing system placed during aortic valve replacement. The

tracing shows simultaneously recorded leads I and II. The tracing most clearly

demonstrates which one of the following?

1.There is failure to sense.

2.The mode of function is VVT

3.Ventricular lead dislodgement.

4.Normal VVI function

5.The patient has a right IVCD

- Taken from Nacarelli et al, ACC EPSAPII.

Board Question 3 (Cont’d)

• Rhythm is atrial flutter. Normal VVI function.

• Spontaneous QRS complexes are LBBB.

• 5th Beat: Fusion.

• 7th Beat: Pure paced from epicardially placed (during valve

surgery) LV lead with RBBB configuration.

• VVT with intermittent undersensing cannot be ruled out

without device interrogation but is unlikely mode.

- Taken from Nacarelli et al, ACC EPSAPII.

Failure To Pace (No Output)

• Battery Failure

• Circuit Failure

• Lead Fracture

• Internal Insulation Failure

• Oversensing

• Loose Set Screw

• Crosstalk

TENS Unit

- Testing revealed no inhibition.

Crosstalk • Lack of Anodal Circuit Contact

– All electricity travels in a circuit (circle) from a

positive pole (anode, ring) to a negative pole

(cathode, tip).

• Incompatible Lead / Header

• Pseudomalfunction

• Most Common: Atrial output sensed by the

ventricle and resetting the VAI.

Board Question 4 • DDI programmed to rate of 86 (VV=697ms), AVI=165ms,

blanking period=13ms.

• Referred for evaluation of abnormal pacemaker function.

• Most appropriate option: 1. Lengthen the PVARP

2. Lengthen the blanking period

3. Lengthen the AVI

4. Lower the rate -Taken from David Hayes, Cardiac Pacing Review for

EP Boards.

Crosstalk: Most Common Presentation

• DDI programmed to rate of 86 (VV=697ms), AVI=165ms, blanking period=13ms.

• Note: All intrinsic V activity, Rate~100?

• VV=AV+VA, VA=VV-AV, VA=697-165=532ms. – 532ms is longer than what we see on strip.

• Measured VV=575ms, 575-532=43ms .

• Blanking period of >43ms should avoid crosstalk. – Decrease atrial stimulus (if adequate safety margin)

– Decrease ventricular sensitivity.

-Taken from David Hayes, Cardiac Pacing Review for

EP Boards.

Crosstalk: Ventricular Safety Pacing • EGM confirming atrial pacing

coinciding with intrinsic ventricular

rhythm and retrograde P-wave in

alternate beats without pacing stimuli.

Note ventricular safety pacing in

alternate beats with atrial pacing (2

vertical lines in marker channel).

• Following atrial pacing, the pacer is

designed to trigger a ventricular pacing

output if ventricular sensing occurs

during the first portion–e.g., 110 ms of

the programmed A-V interval.

• It is difficult to determine whether these

ventricular paced events represent

ventricular safety pacing (VSP) or the

ventricular sense response (VSR)

algorithm. In cases in which both VSP

and VSR are enabled, the VSP

algorithm takes precedence during the

VSP interval within the paced AV delay

interval. Lim S, ―Ventricular safety pacing, ventricular sense response, and

ventricular tachycardia,‖ Heart Rhythm, Vol 7, No 4, April 2010.

Crosstalk: Ventricular Safety

Pacing

• Normal Atrial Capture

• Normal Ventricular Capture with two beats of functional

loss of capture

• Ventricular Sensing Unknown

• Atrial Undersensing with a Pseudo Pseudofusion beat

causing crosstalk with Ventricular Safety Standby seen

- Taken from St. Jude Medical

Failure to Pace:

Lead Fracture / Pseudofracture

Failure to Pace: Air in Header

Atrial EGM

Ventricular

EGM

This patient not pacer dependent.

Loss of Capture

• Dislodgement

• Elevated Thresholds

• Inappropriate Lead

Placement

• Fracture

• Insulation Failure

• Loose set screw

• Exit Block (>4 weeks)

• Perforation

• Battery/circuit Failure

• Air in Pocket

• Metabolic/Drugs

(Flecainide)

Loss of Atrial Capture?: 64 Year Old Female for

Device Check

Loss of Capture in Atrium

Friend of a Friend Calls Two

Weeks after Implant at OSH • Admitted with syncope and tachy-brady.

• DDD placed on right side. Pt is right handed and

hunts.

• Since implant patient sleeps sitting upright and

feels chest ―throb‖ when he lies flat.

• One week f/u with surgeon and device

functioning fine per report and told to ―live with

it.‖

• Pt. calls cardiologist and he echoes implanter’s

recs…‖you’ll have to get used to it.‖

Loss of Capture

• After discussion with friend, I told them to

mention the word ―perforation‖ to the

implanter.

• Implanter’s Response: ―If I perforated,

you’d be dead by now.‖ They did however

check a CXR and then scheduled patient

for ―heart surgery.‖

• Upon evaluation in our device clinic, R

waves sensed at 1.4mV and no V capture

at 2.5V@1.5ms (+diaph capture).

Loss of RV Capture

Other Examples of Perforation

Heart

Border

Signs of RV Perforation

• RBBB paced QRS morphology

– Can see RBBB configuration and

diaphragmatic stimulation in RV apical

position.

• Intercostal muscle or diaphragmatic

stimulation

• Friction rub after implant.

• Pericarditis, pericardial effusion, or cardiac

tamponade.

Failure to Pace after DDD?

Algorithm to Minimize Ventricular Pacing

Oversensing

• Lead fracture (increased impedance)

• Insulation Defect (decreased impedance)

• EMI

• Isoelectric ventricular event

• Sensing T/P waves

• Diaphragmatic potentials from integrated

bipole lead. (Bipole is tip to RV coil giving

larger antenna with which to receive signals)

Shock During Central PA Flooding

• Patient went into flooded basement with socks only.

• Intervals less than 140msec are nonphysiologic.

• Noise is on both atrial and ventricular channels.

13 Year Old Family Friend

Shocked at YMCA

T Wave Oversensing

Undersensing

• Change in intrinsic complex (BBB, VT/VF,

AF)

• MI

• Lead dislodgement / Poor positioning

– Tined leads

• Lead insulation failure

• Magnet application

• ERI

Undersensing

• Normal Atrial Capture with one beat

showing functional loss of atrial capture

• Atrial Undersensing

- Taken from St. Jude Medical

Management of High DFT’s • Reversible Causes: Amiodarone or PTX

• Reverse Shock Polarity

• Remove SVC Coil from Circuit (esp. if Z<40 Ohms)

• Reposition RV Lead

• Add Subcutaneous Array

• Additional Lead: Coronary Sinus or Azygous Vein.

• Optimize waveform tilt (SJM only)

• Consider using sotalol (or dofetilide)

- Mainigi S, Callans D, ―How to manage the patient with a high defibrillation

Threshold,‖ Heart Rhythm, V. 3, No. 4 (April 2006), pp. 492-495.

Failed DFT’s

- I know, there is no ICD.

Board Question 5

• Which of the following configurations is

likely to have the lowest DFT?

1. Distal coil to proximal coil

2. Proximal Coil and can to Distal Coil

3. Distal Coil to SC Array + Can

4. SC Array to Can

- Avoid using Distal Coil + Can to Proximal Coil

What Hardware is Present?

37yo Admitted with Failed DFT

RV lead with high septal position and there is old epicardial patch.

Failed DFT’s in Lab

• EGM1 = Rvtip-Rvring

• LEKG = Can-SVC

• EGM3 = Rvtip-Rvcoil

• EGM2 = Can-RVcoil

Initial Configuration

Corrected Configuration

Arrhythmia Classification

• Use all the available information: surface,

atrial, and ventricular EGMs.

• What ―drives‖ what.

• How does arrhythmia terminate?

• Response to ATP and shocks.

• Morphology during sinus versus

arrhythmia.

What are the Rhythms?

Atrial fibrillation Note morphology

Change to VT

Antitachycardia

Pacing

Diagnose this Arrhythmia

• VAV Response with AVNRT

• When atrium entrained during Vpacing, examine the EMG sequence

immediately after the last paced ventricular complex: – AVNRT = V-A-V response (may also indicate ORT)

– Atrial Tachycardia = V-A-A-V response

- EGM from Ellenbogen, ―ICD’s: Evaluation

and Troubleshooting, 2008 HRS Board Review.

Diagnose this Arrhythmia

• VAAV Response to Overdrive V pacing

with entrainment indicates atrial

tachycardia. - EGM from Ellenbogen, ―ICD’s: Evaluation

and Troubleshooting, 2008 HRS Board Review.

Board Question 6

• A 80 yo male with nonischemic cardiomyopathy (EF15%) and neurofibromatosis

underwent implantation of an ICD for rapid sustained hypotensive ventricular

tachycardia and syncope. He was treated with amiodarone and is undergoing ICD

implant from left subclavian position. He has an existing DDDR pacemaker in the

right subclavian position. The figure shows part of the testing procedure performed

at the time of device implantation. The pacemaker mode is DOO and the output is

programmed to maximal values. It demonstrates which of the following? 1. Testing for double counting.

2. Inhibition of atrial and ventricular pacing by VF.

3. Failure of the ICD to deliver a shock.

- Taken from Nacarelli et al, ACC EPSAPII.

4. Appropriate ICD function during dual

chamber pacing.

5. The requirements for multiple shocks

during pacing to terminate VF.

Board Question 6 (cont’d)

• Appropriate ICD function during dual-chamber pacing.

• Pacer is programmed to DOO at max outputs on atrial

and ventricular channels.

• VF is induced; DOO pacing continues.

• The device is able to sense VF and delivers a shock

to terminate it.

- Taken from Nacarelli et al, ACC EPSAPII.

Acknowledgements • Good Samaritan Hospital

• Lebanon Cardiology Associates

• PA Chapter of the American College of Cardiology

• Drs. Dave Schwartzman, Samir Saba, David Hayes,

Kenneth Ellenbogen.

• Our patients

- Please email me (Jwilliams@lebanoncardiology.com) with

any interesting device-related CXR’s.