Week 8 Advanced CIED Follow-Up - Advanced Follow Up

Troubleshooting: Identifying Issues

• Patient symptoms

  • Syncope/presyncope

  • Palpitations

  • Fatigue

  • Return of pre-implant symptoms

• ECG abnormalities

  • Failure to capture

  • Failure to sense

  • Failure to output

  • Variations in pacing rate

  • Magnet rate indicates ERI/EOS

• Remote monitoring

  • Arrhythmias

  • Device malfunctions

  • Heart failure

  • Advisory/recall

Patient-Related

• Underlying disease state

• Electrolyte imbalance

• Medications

• Tissue substrate changes

• Address patient-related issues first!

System-Related

• Generator

• Header/connection

• Lead integrity

• Lead tissue interface (also a patient issue)

Pacemaker Troubleshooting Process

1. Gather information

2. Run PUBLSTOP

3. Review diagnostic data

4. Simplify device settings

5. Optional:

Evaluate chest x-ray

Invasive evaluation of the system

6. Determine the cause - review

7. Take corrective action

Gather Information

• Pulse generator

• Leads

• Implant data

• Patient symptoms

• Complete device check

Gather Information: Pulse Generator

• Manufacturer

• Model #

• Device capabilities

• Advisory/recall

• Chambers

• Rate response

• Special features

• Date of implant

Gather Information: Leads

• Manufacturer

• Model #

• Date of implant

• Capped leads

• Leads may have different manufacturers/dates

• Recalls/advisories

• Unipolar/bipolar

• Fixation

Gather Information: Patient Information

• Implant data

• Medical records

• CIED indication

• May need to turn off alerts for known condition

Gather Information: Patient Symptoms

• Current symptoms?

• Duration?

• Past symptoms?

• Correlation to activities/time of day?

• Make differential diagnosis

Differential Diagnosis: Palpitations

• Palpitations: possible causes

  • Pacemaker mediated tachycardia - VA conduction test

  • DDD tracking of AF/Flutter - evaluate mode switching

  • Tracking EMI - unipolar leads?

  • VT - analyze episodes/alerts

  • PVCs - track frequency

Differential Diagnosis: Weakness

• Weakness/fatigue: possible causes

  • Failure to capture

  • Inappropriate base rate

  • Need for rate response

  • Pacemaker syndrome

Differential Diagnosis: Dyspnea

• Dyspnea/shortness of breath: possible causes

  • Pacemaker syndrome

  • Need for rate response

  • Underlying cardiac disease (eg. heart failure)

Differential Diagnosis: Syncope

• Syncope/presyncope: possible causes

  • Pacemaker syndrome

  • Underlying disease (Vascular disease, VT, etc.)

  • Crosstalk - check refractory periods/sensitivity

  • Loss of capture - threshold test

Differential Diagnosis: Hiccups

• Hiccups/coughing: possible causes

  • Diaphragmatic pacing

  • Phrenic nerve stimulation

Differential Diagnosis: Muscle Twitching

• Muscle twitching: possible causes

  • Lead insulation failure

  • Unipolar pacing

Differential Diagnosis

Before running tests/making changes, note current programmed settings:

• Mode

• LRL

• MTR/MSR

• AV delays

• Rate response

• Lead polarity

• Intervals

• Algorithms

Loss of Capture

Pacing that fails to lead to myocardial depolarization when it otherwise should have captured

• Excludes functional non capture: pseudo malfunction

• True loss of capture: identify underlying cause and correct

Lead Dislodgement

• Most likely in acute phase of lead implant (within 3 months)

• Interview patient

• Confirm lead type

• Compare current data to implant data

Macro vs. Micro Dislodgement

• May recommend chest x-ray

• Compare to post-implant x-ray

• Macro dislodgement: can be seen on x-ray

• Micro dislodgement: cannot be seen on x-ray

  • More common with passive fixation

Lead Dislodgement Characteristics

• Intermittent loss of capture

• Different morphology when capturing

• Sensing abnormalities

  • Far field oversensing

  • Undersensing

• Normal impedance values

Cross-Chamber Stimulation

• Lead from one chamber stimulates the opposite chamber

• Atrial lead dislodgement across tricuspid valve

• Ventricular depolarization in response to atrial pacing

Cross-Chamber Stimulation Testing

• Pace AAl or AOO to confirm ventricular activation

• Verify with VVI

• Differential diagnoses

  • Lead dislodgement

  • Unipolar pacing

  • Atypical lead placement

  • Leads reversed in header

Perforation

• Lead penetrates through cardiac tissue

• Cathode no longer in contact with myocardium

• Reported in 1-5% of patients

• Chest x-ray or cardiac CT

• Acute perforation: hemodynamically unstable due to tamponade

• Late-occurring perforation: asymptomatic

Perforation Signs and Symptoms

• More likely in patients with weaker heart walls (apical MI)

• Failure to sense

• Loss of capture

• Hematoma

• Pneumonia

• Muscle twitching

• Liver perforation

• Hiccups

Loss of Lead Integrity

• May cause change of impedance: systemic impedance determined by several factors

  • Conductor wires

  • Lead tip

  • Lead-header interface

• Clavicular crush: common cause

Lead Safety Switch

• Automatically changes to unipolar in response to high impedance

• Coaxial leads: eliminates outer conductor

• Only in brady leads

Loose Set Screw

• Usually acute

• Set screw can work loose over time

• Manifests differently depending on degree of contact

  • Failure to output

  • Failure to sense

  • Intermittent loss of capture

  • Intermittent oversensing

Loose Set Screw vs. Dislodgement

• Dislodgement: no change in impedance

• Loose set screw: impedance rises

  • Check unipolar vs. bipolar impedances

  • Loose anodal set screw: high bipolar, normal unipolar

  • Loose cathodal set screw: high bipolar, high unipolar

• Manipulate pocket: may cause

Electromyocardial Interface

• Patient-related issues

  • Myocardial infarction

  • Infiltrative cardiomyopathy (ARVD)

  • Post-shock pacing threshold rise (cardioversion, defibrillation)

• Pacemaker exit block: system-related issue

  • Virtual electrode: fibrous capsule that forms around lead tip

  • Excessive fibrous can cause chronic high thresholds

  • Reduced by steroid-eluting leads

  • Attributed to unknown causes

  • Difficult to differentiate from dislodgement: exit block usually more chronic (> 3 months)

Other Causes of High Thresholds

• Metabolic abnormalities

• Electrolytes

• Medications

• Diabetes

• Hemodialysis

• Dehydration

• Antiarrhythmics

Pseudomalfunctions

• Fusion

• Pseudofusion

• Functional non-capture

• Latency

  • Pacing location (LV, His, epicardial)

  • Near loss of capture

• Isoelectric lead

Loss of Capture Troubleshooting Steps

• Reestablish capture

  • Max outputs

  • Threshold test

  • Reprogram

• Check bipolar impedance

  • High impedance: conductor fracture, loose set screw

  • Low impedance: insulation break

• Check for normal unipolar impedance

  • Outer insulation break

  • Outer conductor fracture

  • Loose anodal set screw

• Chest x-ray: look for macrodislodgement

Undersensing

Device fails to sense and time off of intrinsic signals: any condition that causes change to intrinsic complex

• Metabolics/medications

• Abnormal rhythms

• Myocardial infarction

• Lead dislodgement

• Magnet application

• Battery depletion

• Component failure

• Header abnormalities

• Functional undersensing

Undersensing Effects

• Overpacing: device fails to inhibit

• Competitive pacing: shortly after intrinsic signal

• Secondary effects

  • Functional non capture

  • PAV rather than SAV

  • Safety pacing off of intrinsic QRS

  • Mislabeling of intrinsic QRS as PVC

Medications and Metabolics

• Class IC antiarrhythmics (flecainide): most common medication causing undersensing

• Hyperkalemia: most common metabolic issue causing undersensing

Functional Undersensing

• Intrinsic event falls within blanking/refractory period

• Not sensed or tracked: may influence mode switch

• Pseudomalfunction

Undersensing Troubleshooting

• Determine underlying cause

• Run sensing test: measure intrinsic amplitude

• Fix underlying cause if possible

• If not, make device more sensitive by lowering mV value

• Be careful to avoid oversensing

• Check unipolar sensing if needed

• Check impedance and capture

Oversensing

Device inappropriately senses and times off of signals other than intrinsic depolarizations

• Inappropriate inhibition of pacing: underpacing

• Inappropriate triggering of algorithms

• Inappropriate triggering of ICD therapy

Noise vs. Artifact

• Noise: noncardiac signals sensed by CIED

• Artifact: noncardiac signals seen on EGM by not sensed by CIED

EMI

Electromagnetic interference

• Usually in 30-300 Hz range

• Commonly cyclical appearance

• 60 Hz: standard frequency

• Pacemakers: atrial channel more sensitive

• ICDs: ventricular channel more sensitive

Myopotentials

• Extracardiac muscular activity

• Typically only in one channel

• Can be initiated by physical maneuvers: be careful with pacemaker dependent/ICD patients

Conductor Fractures

usually on one channel

Sensing Conductor Fracture vs. Loose Set Screw

• Loose set screw presents similarly:

  • More acute

  • Test with pocket manipulation

• Check impedance to differentiate from dislodgement

T Wave Oversensing

• Sensing of ventricular repolarization as depolarization

  • Long QT syndrome

  • Hyperkalemia

  • Brugada syndrome

  • Inappropriate programming

• Troubleshooting

  • Extend VREF

  • Adjust sensitivity value

  • Other sensing parameters

  • Switch to integrated bipolar

R Wave Double Counting

• Sensing ventricular depolarization twice

  • Delays in ventricular conduction

  • Bundle branch block

  • Class IC antiarrhythmics

  • Hyperkalemia

  • Loss of capture

• Address underlying cause

• Adjust blanking period if needed

Farfield Oversensing

• Intrinsic signals in one chamber sensed in opposite chamber

  • R wave/T wave oversensing on atrial channel: most common cause of inappropriate mode switching

  • P wave oversensing on ventricular channel: His bundle lead

• Run sensing test

• Decrease sensitivity by increasing mV value

• Increase PVAB/PAVB if necessary

Crosstalk

• VA crosstalk: sensing V pacing pulse on atrial channel

• AV crosstalk: sensing A pacing pulse on ventricular channel

• Run sensing test

• Decrease sensitivity

• Increase blanking period

  • Increase PVAB to prevent VA crosstalk

  • Increase PAVB to prevent AV crosstalk

• Lower outputs if possible

ICD Leads

• All leads vulnerable

  • Millions of cardiac cycles

  • Hostile environment

• ICD leads: particularly vulnerable

  • More components

  • Higher voltages

  • Multilumen design

  • Single or dual coil

  • Dedicated or integrated bipolar

  • IS-1/DF-1 or DF4

ICD Lead Recalls

• Medtronic Sprint Fidelis

  • Highly flexible

  • Conductor fractures of tip electrode coil and ring electrode cable

• St. Jude Riata Family

  • Large-diameter lumens

  • Inside-out insulation breach

  • Externalized cables

  • Connections between conductors

Pace-Sense Failure

• Seen with conductor fractures and insulation breaches

  • Oversensing of fast nonphysiologic signals

  • Inhibition of pacing

• Inappropriate therapy

• Loss of capture

• Undersensing

Shock Component Failure

• Likely underreported

• Failed defibrillation

• Complete pulse generator failure

• Hopefully catch beforehand

Analyzing EGMs

• Signals on sensing channel but not farfield: usually noncardiac

• Look at stored episodes

• Use real time EGMs

  • Pocket manipulation to rule out poor lead-header connection

  • Exercises to rule out myopotentials

Insulation Breaches

• EGMs less fully studied

• Abnormal signals generated by secondary effects

  • Outside-in breach: myopotentials

  • Inside-out breach: spikes on sensing and shock channels from cables rubbing against each other

Lead Impedance

Effective resistance of an electric component to alternating current, arising from combined effects of ohmic resistance and reactance

• Higher impedance: lower current flow at same voltage

• Ohm's law: V = IR

• Pacing impedance: measured through subthreshold impulse

  • Lead-tissue interface (most of systemic impedance)

  • Conductors

  • Lead-header interface

• Normal range: 300-1800 ohms

• Changes to impedance more indicative of failure

Shock Impedance

• Measured through low-energy shock

• Shock circuit:

  • Lead-header connection

  • High-voltage conductors

  • Shocking coils

  • Anatomical features

• Single coil leads: 30-110 ohms

• Dual coil leads: 20-70 ohms

• Low-voltage measurement not very accurate

High Voltage Failure

• High voltage conductor fracture

  • Abrupt impedance increase

  • Absolute value > 100 ohms

• High voltage insulation breach

  • May cause impedance decrease

  • Difficult to diagnose with low voltage pulses

  • Can cause catastrophic short-circuit

Lead Failure Algorithms

• Rapid oversensing

• Impedance changes

• Lead safety switch: change to unipolar

  • Cathodal conductor only

  • Works best with coaxial brady leads

• Lead integrity alert: ICD leads

  • Impedance changes

  • Frequent isolated rapid intervals

  • Nonsustained VT with rapid intervals

  • Audible tone, RM alert, extends detection durations

  • Some algorithms withhold shocks for nearfield-only signals

Impedance Troubleshooting

• Impedance not very sensitive or specific, especially low-voltage shock impedance

• Monitor single out of range impedance or gradual rise over time

• Reprogram to unipolar/integrated bipolar

• Assess time frame

• Chest x-ray if needed

• Patients with at-risk leads

  • Education

  • Remote monitoring

  • Programming changes

  • Often replace during gen. change

Pacemaker Syndrome Definition

• Initially associated with RV pacing

• Later associated with several factors:

  • Loss of AV synchrony

  • Loss of V-V synchrony

  • Retrograde VA conduction

  • Lack of rate response

Loss of AV Synchrony

• Atrial systole: 10-30% cardiac output

• Ventricles contract too late: blood flows backward

• Ventricles contract too early: atria contract against closed valve

• Symptoms:

  • Dizziness

  • Syncope

  • Dyspnea

  • Fatigue

  • Palpitations

  • Distended neck veins

  • Hypotension

  • Heart failure

Pacemaker Syndrome Causes

• VVI devices

  • No AV synchrony

  • Retrograde VA conduction

  • Only indicated for permanent AF w/SVR or ICD patients with no pacing indications

• DDD devices

  • Chronotropic incompetence with no rate response

  • RV pacing: V-V dyssynchrony

  • Algorithms to promote intrinsic conduction: AV dyssynchrony

Pacemaker Syndrome Symptoms

• Dyspnea on exertion

  • Decreased CO

  • Chronotropic incompetence

  • Worsening heart failure

• Heart failure:

  • Nocturnal dyspnea

  • Orthopnea

  • Edema

  • Weight gain

  • Lung sounds

• Vascular symptoms

  • Hypotension

  • Syncope/presyncope

  • Related to decreased CO

• Fatigue

• Headache

• Dizziness

Physical Examination

• Palpitations

• Drop in systolic BP of > 20 mmHg when turning pacing on

• Cannon A waves

  • Atria contract against closed AV valves

  • Blood regurgitates backward

  • Pulsation in neck/abdomen

  • Waveform on central venous pressure tracing

  • Seen with RVAC, CHB, pulmonary HTN, VT

Pacemaker Syndrome at Follow Up

• Run tests in a way that feels best for patients

• DDD maintains AV synchrony

• Be careful when coming on pacing

• Monitor patient for symptoms

Programming Considerations

• VVI: reduce pacing

  • Decrease rate

  • Rate hysteresis

  • Rate response off

• Permanent AF: compensate for loss of atrial kick

  • Increase base rate

  • Turn rate response on

• DDD: balancing act

  • Algorithms that promote intrinsic conduction reduce RV pacing, can cause AV dyssynchrony

  • CHB and CRT patients should have shorter AV delays

  • Rate response drives pacing in the atrium: physiologic

  • CRT: algorithms to promote BIV pacing

P Wave Abnormalities

• Right atrial abnormality: change to beginning of P wave

  • Tall, peaked P wave

  • COPD

  • Pulmonary HTN

  • Congenital heart disease

  • RVHF

• Left atrial abnormality: change to end of P wave

  • Wide, notched P wave

  • CAD

  • Cardiomyopathy

  • HTN

  • Valvular heart disease

Aberrancy

• Abnormal intraventricular conduction of a supraventricular impulse

• One or more components of distal conduction system refractory when impulse arrives

  • Different conduction pathway

  • Any supraventricular impulse that is early enough

PACs: Three Possible Outcomes

A: Nonconducted PAC

B: Aberrant RBBB Pattern

C: Normal QRS Complex

Importance of Underlying Rate

• Refractory periods determined by heart rate

  • Slower rate: longer

  • Faster rate: shorter

• Longer PAC intervals will cause aberrancy at slower rates

Atrial Extrastimulus Pacing

Mimics PAC: can cause aberrancy

Drug Toxicity and Electrolytes

Anything that alters the action potential can cause aberrancy:

• Electrolyte abnormalities

  • Hypocalcemia

  • Hypercalcemia

  • Hyperkalemia

• Medications

  • Class IC antiarrhythmics (flecainide)

Rate Related Aberrancy

• Aberrancy can result from rapid acceleration and deceleration as well as high overall rates

• Rate related bundle branch block:

  • Every beat falls within bundle branch refractory period

  • Usually RBBB pattern

  • Occurs at critical rate: similar to Wenckebach

  • Rate is lower in diseased hearts

Aberrancy in ICDS

• Transvenous ICD: morphology discriminator

  • Patient exercising: sinus rate reaches VT zone

  • Morphology discriminator will label aberrancy as VT

  • Turn morphology off or turn on other discriminators

• SICD: subcutaneous ECG

  • Aberrancy can cause R wave double-counting

  • Changes to T wave can cause T wave oversensing

  • Rate appears double

  • Change sensing vector

Ashman Phenomenon

Aberrant ventricular conduction due to changes in QRS cycle length

• Associated with AF: irregularly irregular conduction

• Long-short rule: the earlier in the cycle the PAC occurs and the longer the preceding cycle, the more likely the PAC will be conducted aberrantly

Rhythm Differentiation

• VT, SVT with aberrancy, or antidromic AVRT?

• 12 lead: AV relationship, axis, R wave progression, durations

• EGMs: more difficult

  • Don't assume one or the other

  • Physician may want additional testing

Rhythm vs. Rate Control

• Rhythm control:

  • Prevent arrhythmias

  • Terminate arrhythmias

  • Restore normal sinus rhythm

• Rate control:

  • Slow conduction through the AV node

  • Reduce ventricular rate during supraventricular arrhythmias

Mechanisms of Tachycardia

Antiarrhythmics target different mechanisms: most commonly reentrant circuit by altering conductivity/refractoriness

• Reentry: electrical impulse caught in self-propagating loop

• Abnormal automaticity: non-pacemaker cells display automaticity

• Triggered activity: afterdepolarizations trigger new action potential

Antiarrhythmic Actions

• Phase 0: increase/decrease conduction velocity

• Phase 3: change duration of ERP

• Phase 4: suppress abnormal automaticity and triggered activity

• Autonomic tone: chronotropy, inotropy, dromotropy

Vaughan-Williams Classification

• Class I: sodium channel blockers

• Class II: beta blockers

• Class III: potassium channel blockers

• Class IV: calcium channel blockers

• Class V: parasympathetic stimulation

Class I: Sodium Channel Blockers

Divided into three subclasses:

• Class IA: moderate influence on phase 0

• Slow conduction velocity

• Prolong repolarization

• Extend AP duration

• Procainamide, quinidine, disopyramide

• Risk of Torsades de Pointes, GI upset, enhanced AV conduction, hypotension

• Class IB: weak influence on phase 0

• Little impact on conduction velocity

• Shorten repolarization

• Decrease AP duration

• Lidocaine, mexiletine, phenytoin, tocainide

Class IC: strong influence on phase 0

• Repolarization unchanged

• No effect on AP duration

• Slow conduction to break or prevent arrhythmias

• Flecainide, propafenone, encainide, moricizine

Class IC Risks

• Flecainide: contraindicated for CAD/SHD patients

• Flecainide/propafenone: VT, CHF, enhanced AV conduction

• Flecainide: most documented impact on pacing thresholds

Classes Subclasses Explained

Class 1a: A affects all

Class 1b: B brings the Back end in

Class 1c: C changes conduction and capture

Class II: Beta Blockers

• Decrease sympathetic tone

• Block myocardial beta-adrenergic receptors

• Prevent binding of norepinephrine/epinephrine

• Impact SA node, AV node, blood pressure

• "Lol" drugs: esmolol, metoprolol, propranolol...

Class III: Potassium Channel Blockers

• Prolong repolarization

• Increase AP duration

• Longer refractory periods, no effect on conduction velocity

• Blocks reentry

• Amiodarone, sotalol, dronedarone, ibutilide, dofetilide

Class III Risks

• Lengthen QT interval: risk of Torsades de Pointes

• Monitor during initial dosing

• Sotalol: Torsades, CHF, bradycardia, bronchospasms, lowers DFTs

Aminodarone

• Low risk of Torsades

• Most commonly used antiarrhythmic

  • Stable monomorphic VT

  • Hemodynamically unstable AF

  • AF refractory to electrical cardioversion

• Cross-class characteristics

• Side effects: lung toxicity, pulmonary fibrosis, hepatic upset, vision problems, hyperthyroidism, neurologic toxicity, blue-gray skin, AV block, hypotension, GI upset, bradycardia, photosensitivity, arrhythmias, death

• Raises DFTs

Class IV: Calcium Channel Blockers

• Influence SA and AV nodes

• Affect transition from phase 4 to phase 0 of slow AP

• Depress automaticity

• Slow heart rate

• Decrease contractility

• Diltiazem, verapamil

Class V: Parasympathetic Stimulation

• Increased parasympathetic stimulation

• Similar effect to beta blockers

• Rhythm and rate control

• Digitalis/digoxin, adenosine, magnesium sulfate

Digitalis

• Activates vagal nerves

• Slows signals from SA node

• Slows AV conduction

• Prolongs AV node refractory period

• Positive inotrope: used to treat heart failure

• Toxicity: nausea/vomiting, neurological effects, tachyarrhythmia

Adenosine

• Transient depression of SA node and AV node

• Temporary AV nodal block

• Cardioversion of AV nodal dependent SVTs (AVRT, AVNRT)

• Diagnosis of non AV nodal dependent SVTs (AT, AFlutter)

Antiarrythmics Drawbacks

• Only moderately effective:

  • 40-50% during initial usage

  • 30% during prolonged usage

  • 10% discontinue due to side effects

• Many physicians seek nonpharmacologic treatments

Antiarrhythmics Effect on CIEDs

• AF burden

• PVC count

• Episodes

• Beta blockers: brady indication

• Flecainide: increased pacing thresholds

• Amiodarone: increased DFTs