How to programme and follow up a pacemaker BCS Glasgow 2006 Technical Aspects of a Pacemaker

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How to programme and follow up a pacemakerBCS
Glasgow 2006 Technical Aspects of a Pacemaker

• Mr Stuart Allen.
• Southampton General Hospital.

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Goals of a Pacemaker ClinicTechnical
Physiological

• Satisfy BPEG/HRuk Guidelines
• Electrical characteristics/Battery Check
• Histograms/Diagnostics/ Arrhythmia
  analysis/evaluation
• Physiological needs of patient
• Prediction of potential problems
  Clinical/electrical
• Troubleshooting
• Majority of patients fall in to the category of
  routine follow up

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Common Referrals for Pacemaker Checks

• My SHO/Registrar told me to ask for it!
• No Pacing spikes on ECG.
• Patient has a pacemaker implanted. Can we check
  it? (no other reason given)
• Syncope/Dizzy Spells/Palpitations. ?Pacemaker
  working.
• If the ECG shows normal pacing and the patient
  is free of any symptoms there is unlikely to be a
  pacemaker/lead problem
• Pre/ Post surgery
• Augment cardiac output
• .

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Ask the right questions!

• Pacemakers can help answer key clinical questions
  regarding device status, clinical status and
  arrhythmia status of the patient.
• Pacemakers can give useful insight into disease
  progression and long-term patient management
  questions.

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Most Pacemakers Perform Four Functions

• Stimulate cardiac depolarization
• Sense intrinsic cardiac function
• Respond to increased metabolic demand by
  providing rate responsive pacing
• Provide diagnostic information stored by the
  pacemaker

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Potential Problems Identifiable on an ECG Can
Generally Be Assigned to Five Categories

• Undersensing
• Oversensing
• Noncapture
• No output
• (Pseudomalfunctions)

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Paced Rhythm Recognition
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Electrical Characteristics

• Lead threshold(s)
• Lead Impedance(s)
• Sensing threshold(s)
• Battery voltage/Current drain
• Battery impedance
• Longevity

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Typical Follow-Up Activities
Percent of Follow-Up Time
Marshall M, Butts, L, Flaim, G, et al. Predictors
of time requirements for pacemaker clinic
evaluation. PACE 1995 18 Pt II952.
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Stimulation Threshold
2.0 v
1.5 v
1 v

• The minimum output pulse neededto consistently
  capture the heart

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Threshold Trending
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Sensitivity

• The degree that the pacing system sees or
  senses signals, controlled by the sensitivity
  setting which is graduated in millivolts (mV)

Sensitivity (mV)
5 (mV)
2.5 (mV)
1.25 (mV)
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Undersensing

• An intrinsic depolarization that is present, yet
  not seen or sensed by the pacemaker

Atrial Undersensing
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Undersensing May Be Caused By

• Inappropriately programmed sensitivity
• Lead dislodgment
• Lead failure
• Insulation break conductor fracture
• Lead maturation
• Change in the native signal

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Oversensing

• The sensing of an inappropriate signal
• Can be physiologic or non-physiologic

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Noncapture May Be Caused By

• Lead dislodgment
• Lead perforation
• Low output
• Lead maturation
• Poor connection in the header
• Lead failure

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Less Common Causes of Noncapture May Include

• Twiddlers syndrome
• Electrolyte abnormalities
  e.g. hyperkalemia
• Myocardial infarction
• Drug therapy
• Battery depletion
• Exit block

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Non Capturedue to Atrial Lead Displacement
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Lead Impedance Measurement

• High Lead Impedance
• Open Circuit e.g. lead not connected to device
  (Set Screw)
• Lead fracture
• Low Lead Impedance
• Partial lead/insulation break fluid ingress
• Fluid/blood in header

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An Insulation Break Around the Lead Wire Can
Cause Impedance Values to Fall

• Insulation breaks expose the wire to body fluids
  which have a low resistance and cause impedance
  values to fall
• Current drains through the insulation break into
  the body which depletes the battery
• An insulation break can cause impedance values to
  fall below 300 ohms

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A Wire Fracture Within the Insulating Sheath May
Cause Impedance Values to Rise

• Impedance values across a break in the wire will
  increase
• Current flow may be too low to be effective
• Impedance values may exceed 3,000 ohms

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Normal Impedance Trend
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High Lead Impedance indicating possible lead
fracture
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Pseudomalfunctions

• Pseudomalfunctions are defined as
• Unusual
• Unexpected
• ECG findings that appear to result from pacemaker
  malfunction but that represent normal pacemaker
  function eg Pacemaker Mediated Tachycardia (PMT).

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Pseudomalfunctions Pacemaker Mediated Tachycardia
PVC
Retrograde P waves
PVARP
PVARP
PVARP
PVARP
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Pacemaker DiagnosticsLead Monitoring

• Automatically included on this initial
  interrogation report

Measured Data includes Lead impedance lead Status
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Diagnostics, Histograms Arrhythmia analysis

• Majority of pacemaker
• patients fall into the category of routine
  follow-up.
• Routine Follow-up
• Interrogate Review
• Remaining Longevity
• A and V Thresholds
• A and V Impedances
• P- and R-Wave Ampl
• Histograms and Pace/Sense History

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Atrial High Rate Episode

• AF Verified
• Effect on Ventricular Rate suspected

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Ventricular Rate Histogram DuringAtrial High
Rate Episodes

• Evaluate
• Rate Distribution
• Time in High Rate
• V-pace vs. V-sense
• Ventricular Histogram

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Patient Presenting with TIA12 lead ECG shows
NSR/ 24hr Holter monitor NAD
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Patient Presenting With Syncope
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Physiological Programming

• Rate Rate Response
• Promotion of intrinsic conduction
• Anti Arrhythmic functions

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Rate Responsive Pacing

• When the patients exercise increases, the
  pacemaker ensures that the heart rate increases
  to provide additional cardiac output

Adjusting Heart Rate to Activity
Normal Heart Rate
Rate Responsive Pacing
Fixed-Rate Pacing
Daily Activities
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A Variety of Rate Response Sensors Exist

• Those most accepted in the market place are
• Activity sensors that detect physical movement
  and increase the rate according to the level of
  activity
• Minute ventilation sensors that measure the
  change in respiration rate and tidal volume via
  transthoracic impedance readings
• Blended sensor of activityMV
• QT interval
• Sensitivity of the Rate Response sensor can be
  set in each patient

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Why Promote Intrinsic Conduction

• Right ventricular (RV) pacing alters the normal
  myocardial electrical activation sequence leading
  to regional wall motion abnormalities of the left
  ventricle (LV).
• Histopathologic abnormalities of the myocardium
  have been identified with prolonged ventricular
  pacing of the mature and immature heart.

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Promoting Intrinsic Conduction

• Programming AV interval (Search AV)

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Arrhythmia Management

• Atrial Pacing Preference for suppression of APCs
  that may cause AF
• Anti Tachycardia pacing for Atrial flutter
• Ventricular Rate Regulation for AF

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The future.Remote Patient Management

• Internet-based system providing full device
  interrogation data
• All programmed parameters
• Stored episodes with electrograms
• 10 second electrogram captured at interrogation
• All reports available on programmer available for
  display and printing

Secure Network
CareLink? Monitor
Patient Website
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Thank You