AICD and Pacemaker Update

AICD and Pacemaker UpdateKathryn Gray CRNA

•Excitability: The ability of a cell to respond to a stimulus by depolarizing and propagating an action potential•Depolarization: Occurs when there is a decrease in the polarity across a cell membrane.•Hyperpolarization: Occurs when there is an increase in the polarity across a cell membrane. •Conductivity: The ability of a cell to transmit action potentials to adjacent cells. •Rhythmicity: The ability of cells to generate automatic action potentials.

Terminology:

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Where it all begins…………

Lets get nerdy… This equation is used to define the electrical

gradient across a membrane based on ion concentrations

This can be applied to cardiac myocytes which helps to explain the ion potentials during AP propagation and RMP.

Ion [Intracellular]

[Extracellular]

Equilibrium potential (Em)

Sodium 10 mM 145 mM 60 mV

Potassium 135 mM 4 mM -94 mV

Chloride 5 mM 120 mM -97 mV

Calcium 0.00000010 mM

2 mM 132 mV

Nernst Equation Em= (-RT/zF) X log [K]i/[K]o

•Em is the equilibrium potential of the ion based on transmembrane concentrations.•R-universal gas constant (8.314472 JXK -1)•T- absolute temperature (273.15 degrees kelvin)•[K]i- potassium concentration on the inside of the cell•[K]o-potassium concentration on the outside of the cell.•z- the number of electric charges carried by a single potassium ion•F- the Faraday constant (9.6485309 X104 cmol-1)

Paging Dr. Nernst

Lets get really nerdy…The Goldman-Hodgkin-Katz equation

accounts for the ionic potentials of multiple ions across a cell membrane.

EMF= 61.5 X log([Na]iPNa+[K]iPK+[Cl]oPCl)

([Na]oPNa+[K]oPK+[CliPCl)

•The SA node is made up of specialized cardiac muscle cells which do not have contractile abilities. •The SA node is the primary pacemaker in the cardiac conduction system. •It’s intrinsic rate is faster than the other latent pacemakers in the heart and thus overrides them.• It’s automaticity and intrinsic rate is dependant upon *calcium leak channels in the sarcoplasmic reticulum.

The Sinoatrial Node

At the cellular level

SA Node conduction

•This is a portion of the heart with a more rapid rate than the sinus node.•Also occurs when transmission from the SA node to A-V node is blocked (A-V block).•During sudden onset of A-V block, sinus node impulses do not get through, and next fastest area of discharge becomes pacemaker of heart beat.•Delay in pickup of the heart beat is called “Stokes-Adams” syndrome. The new pacemaker is in A-V node or penetrating part of A-V bundle.

Ectopic Pacemakers

AV nodeThe AV node contains highly specialized tissue

that slows impulse conduction considerably

thereby allowing sufficient time for complete atrial

depolarization and contraction prior to

ventricular depolarization and contraction.

Purkinje FibersLocated in the inner

ventricular walls of the heart, just beneath the endocardium.

The Purkinje fibers have the fastest conduction speed of any fibers in the heart.

The ventricles

Normal ventricular RMP is -80 to -90mVAction potential is accelerated once threshold is reached by the opening of fast Na channels and slow Ca channels.

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Depolarization during a cardiac cycle

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Innervation of the heart

Releases norepinephrine at sympathetic ending

Causes increased sinus node firing rate

Increases rate of conduction impulse

Increases force of contraction in atria and ventricles

Parasympathetic (vagal) nerves, Release acetylcholine at

their endings innervate S-A node and A-

V junctional fibers Causes

hyperpolarization because of increased K+ permeability in response to acetylcholine

Muscarinic Acetylcholine Receptors, when stimulated cause decreased heart rate

Sympathetic Parasympathetic

CNS control of Heart rate

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Causes of cardiac dysfunction

Temperature extremes pH imbalances Hypo or Hypercalcemia Malnutrition, cachexia Hypoxia/Ischemia Hypo or hyperkalemia Autonomic imbalances Hypo or hypercarbia Magnesium deficiency Drug toxicity and adverse

drug reactions Stress and catecholamine

release

CAD HTN Dilated myopathy Morbid obesity Advanced age CHF Chronic lung disease and

subsequent cor pulmonale Endocrine imbalance Hypertropic myopathy Sick sinus syndrome Increased ICP Renal disease

Physiologic Imbalances Associated Co-motbidities

Types of conduction disruptions - Atrial Fibrillation - Atrial Flutter - 1st degree heart block - 2nd degree heart block - 3rd degree heart block - Ventricular fibrillation - Ventricular tachycardia - Re-entry arrhythmias

The Solution:

And the beat goes on….

Pacemaker coding system

Chamber Paced

Chamber Sensed

Response to Sensing

Programmability

Antiarrhythmia Function

A=Atrium A=Atrium T=Triggered P=SimpleC=Communicating

P=Pacing

V=Ventricles V=Ventricles I=Inhibited R=Rate modulation

S=Shock

D=DualBoth atria and ventrical

D=DualBoth atria and ventrical

D=DualBoth triggered and inhibited

M=Multiprogram

D=DualBoth pacing and shock

O=None O=None O=None O=None O=None

Who gets what?

CODE What is it? Who gets it?

AOO Atrial pace, no sense no inhibitions

SSS with intact conduction in the OR with bovie

AAI Atrial pace, atrial sense, inhibition by the atrium

SSS with intact conduction system

VOO Ventricular pace, no sense no inhibition

Third degree heart block in OR with atrial fibrillation

VVI Ventricular pace, ventricular sense and ventricular inhibition

Third degree heart block with atrial fibrillation

DOO Dual pace, no sense no inhibitions

Third degree heart block in OR with bovie

DVI Dual pace, ventricular sense, ventricular inhibition

Third degree heart block with SVT

DDD Dual pace, dual sense dual inhibit

Third degree heart block

The name is Bond, James Bond

This is a schematic of how each pacemaker will affect the EKG depending on the intrinsic beat and pacemaker mode

Rate Responsive Pacemakers

Rate-Responsive Direct metabolic sensors: 1. Mixed Venous O2 saturation 2. Central venous pH

In-Direct metabolic sensors: 1. Ventilation rate 2. Mixed Venous Temperature

Non-Metabolic Physiological sensors 1. QT interval 2. Ventricular Depolarization Gradient 3. Stroke Volume 4. Mean Arterial Blood Pressure

Direct Activity sensors 1. Motion detection

Pacemaker effects on CO

Anesthesia and in situ pacemakersElectromagnetic interference is

always a problem when taking a person into the OR for a surgical procedure.

Increase in Pacemaker threshold with some drugs in the OR setting.

Physiologic alterations can change pacemaker function.

Questions you need to ask before going into the OR What is the device?

What brand and model? Does your hospital have a programmer for this

make and model? What is the magnet mode? Why does the patient have a pacemaker? What rhythm does the patient have when the

pacemaker is shut off? When was the last time it was interrogated? How long has it been since the battery has been

changed?

AICD’s

Indications for AICD insertionCommon indications for AICD implantation

Class I indications Class II indications

History of prior MI •LVEF < 35% & NYHA class II/III•LVEF <30% & NYHA class I•Hemodynamically unstable•History of VF and VT inducible in the EP lab

•LVEF < 30% or 35% & NYHA class I•Recurrent VF and normal LVEF

Chronic myocarditis, pericardial disease, hypertrophic or infiltrative cardiomyopathy

• History of spontaneous, sustained VF/VT associated with primary pathology

Non-iscemic dilated cardiomyopathy

•History of sustained VF/VT and significant LV dysfunction

•Unexplained syncope & LV dysfunction•Reccurrent VF/VT normal LVEF

Hyoertrophic cardiomyopathy

•History of documented VT/VF

IT DEPENDS!!

What do you do when your patient has an

existing pacemaker or AICD?

•Questions to ask the patient:•Why do they have an AICD? •How long have they had it?•Who is the manufacturer?•When was the last time it was interrogated?•When was the last time they received an AICD shock?•How often do they get shocked?

Anesthesia for patients with AICD’s

Danger in the O.R.

Electrocautery

Bipolar vs UnipolarWhy do we need a grounding pad?

Why are we afraid of bovie with pacemakers and AICD’s?

Electromagnetic interference in the O.R.

Electrocautery MRIESWLDefibrillationMotor evoked potentialsNerve stimulators

Oversensing Cause

Insulation breach Bipolar impedance

Pacemaker oversensing

Pacemaker undersensing

Failure to capture

Innapropriate AICD shock

The Magic Magnet

The magnet IS NOT magical!!!

Don’t be lured in to a false sense of security of “I’ll just put a magnet on it” to fix any problems.

Magnet Mode

The pacemaker mode temporarily switches to VOO in single chamber devices and DOO in dual chamber devices.

Asynchronous pacing delivers output regardless of intrinsic activity

Pacing rate will be 85 bpm for pacemaker battery levels above ERI (elective replacement indicator) and 65 bpm for battery levels below ERI*

When the magnet is removed, the previously programmed mode returns*

Use when:Checking pacemaker battery levelEMI is present (surgery, TENS, etc.)Device troubleshooting (breaking a PMT, assessing capture,

etc.)

What happens when a magnet is applied over a pacemaker?

Magnet Mode What happens when a magnet is placed

over an AICD? If the patient is not pacemaker

dependant…. If the patient is pacemaker dependant…

So what are the recommendations?

De-fasciculation prior to succinylcholine is recommended if the patient has a RR pacemaker

Question the use of Nitrous if the pacemaker is new

Inhalation agents and propofol do not affect pacing thresholds.

What other monitors do I need? YOU DO NOT ALWAYS NEED TO TURN OFF THE

AICD OR PACEMAKER!

Recommendations Atropine should be close at hand if

the patient should have severe bradycardia.

A patient with an AICD or pacemaker should NEVER be sent home without the device being interrogated by a representative of the device’s company if a magnet has been used.

What about ACLS with AICD’s and pacemakers?

Recommendations:

Perioperative management of these patients should be individualized.

The best type of anesthesia for the patient with an AICD or pacemaker depends on the type of surgery and the patient’s co-morbidities

Bipolar is better If using monopolar cautery, place pad close to incision

site and keep bursts to less than 5 seconds. Cardioversion will reset the device If below the umbilicus the risk of EMI is very low with a

pacemaker. Surgery below the umbilicus in the patient with an AICD

may still create risk of innapropriate shock.

Recommendations All volatile anesthetics depress cardiac contractility

by decreasing calcium into cells during depolarization

NEVER TURN OFF A PACEMAKER OR AICD WITHOUT HAVING THE PATIENT HOOKED UP TO EXTERNAL PACING/DEFIBRILLATION PADS!!!!

Important phone numbers Biotronik 800.547.0394 Boston Scientific 651.582.4000 Sorin Ela 800.352.6466 Medtronic 800.328.2518 St. Jude Medical 800.722.3774

Preoperative Recommendations: All patients with pacemakers undergoing

elective surgery should have had a device check as part of routine care within the past 12 months that identifies the required elements specified below.

• All patients with ICDs undergoing elective surgery should have had a device check as part of routine care within the past 6 months.

Emergency recommendations Identify the type of device Determine if the patient is pacing Pacemaker dependent— Yes: pacemaker (not ICD)— Yes: ICD and pacemaker— No: pacemaker (not ICD)— No: ICD and pacemaker What if I need a central line?

Procedure specific recommendations Monopolar electrosurgery CIED evaluated within 1 month from

procedure External cardioversion CIED evaluated prior to discharge or transfer

from cardiac telemetry Radiofrequency ablation CIED evaluated# prior to discharge or transfer

from cardiac telemetry Electroconvulsive therapy CIED evaluated# within 1 month from

procedure unless fulfilling Table 9 criteria Nerve conduction studies (EMG) No additional CIED evaluation beyond

routine Ocular procedures No additional CIED evaluation beyond routine Therapeutic radiation CIED evaluated prior to discharge or transfer from

cardiac telemetry; remote monitoring optimal; some instances may indicate interrogation after each treatment (see

text) TUNA/TURP No additional CIED evaluation beyond routine Hysteroscopic ablation No additional CIED evaluation beyond routine Lithotripsy CIED evaluated# within 1 month from procedure unless

fulfilling Table 9 criteria Endoscopy No additional CIED evaluation beyond routine Xray/CT scans/mammography No additional CIED evaluation beyond

routine #This evaluation is intended to reveal electrical reset. Therefore, an

interrogation alone is needed. This can be accomplished in person or by remote

Pacemaker and AICD policyEach facility should have a

pacemaker and AICD policy. You should find and become familiar with yours.

When dealing with patients who have pacemakers or AICD’s, please use these policies to guide you since these are what you will be measured by if there are any problems.

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Questions?Thank

You!!!