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CARDIAC IMPLANTABLE ELECTRONIC DEVICES (CIED) :
PACEMAKERS,IMPLANTABLE CARDIOVERTER
DEFIBRILLATORS(ICD)
Moderator : Dr Manju Mani
www.anaesthesia.co.in
BRIEF HISTORY First totally implantable pacemaker :
into the chest of 43 yr old Arne Larsson by Dr Ake Senning in Stockholm on Oct 8 ,1958.
Introduction of external defibrillators in 1962
First internally implanted defibrillator in 1980
PACEMAKERDevice that provides electrical
stimulation to cause cardiac contraction when intrinsic cardiac electrical activity is slow or absent
PACEMAKER FUNCTIONS1. Stimulate cardiac depolarization2. Sense intrinsic cardiac function3. Respond to increased metabolic
demand by providing rate responsive pacing
INDICATIONS FOR PACEMAKER
1. Aquired AV block
- 30 AV block
Symptomatic bradycardiaAsystole >3 sec or escape rhythm <40bpmPost op AV block not expected to resolveNeuromuscular disease with AV block
- 20 AV block
Permanent or intermittent symptomatic bradycardia
2. After MI
Symptomatic 20 AVB or 30 AVB Infranodal AV block with LBBB
3. Bifascicular or Trifascicular block
intermittent complete heart block with symptoms
2 AV block Bundle branch block
4. Sinus Node Dysfunction - with symptoms as a result of long term
drug therapy - symptomatic chronotropic
incompetence
5 . Hypertensive carotid sinus & neurocardiac symptoms
- recurrent syncope associated with carotid sinus stimulation
- Asystole of > 3 sec duration in absense of any medication
PACEMAKER COMPONENTS
AND ANATOMY
PACEMAKER COMPONENTS
Pulse Generator Electronic Circuitry Lead System
PULSE GENERATOR Subcutaneous or submuscular Lithium battery 4-10 years lifespan long life and gradual decrease in power
sudden pulse generator failure is an unlikely cause of pacemaker malfunction
ELECTRONIC CIRCUITRY Sensing circuit Timing circuit Output circuit
LEAD SYSTEMBipolar Lead has both
negative, (Cathode) distal and positive, (Anode) proximal electrodes
Separated by 1 cm Larger diameter:
more prone to fracture
Compatible with ICD
Unipolar Negative
(Cathode) electrode in contact with heart
Positive (Anode) electrode: metal casing of pulse generator
Prone to oversensing
Not compatible with ICD
BIPOLAR
current travels only a short distance between electrodes
small pacing spike: <5mm
Anode
Cathode
+
-
UNIPOLAR
current travels a longer distance between electrodes
larger pacing spike: >20mm
Anode
Cathode
+
-
PACED RHYTHM RECOGNITION
VVI / 60
PACEMAKER CODE DEVELOPED AS JOINT PROJECT BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) - REVISED 2002
IChamber
Paced
IIChamberSensed
IIIResponseto Sensing
IVProgrammableFunctions/Rate
Modulation
VAntitachy
Function(s)
V: Ventricle V: Ventricle T: Triggered P: Simple programmable
P: Pace
A: Atrium A: Atrium I: Inhibited M: Multi- programmable
S: Shock
D: Dual (A+V) D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S)
O: None O: None R: Rate modulating O: None
S: Single (A or V)
O: None
O: None
COMMON PACEMAKERS VVI
Ventricular Pacing : Ventricular sensing; intrinsic QRS Inhibits pacer discharge
VVIRAs above + has biosensor to provide Rate-
responsiveness DDD
Paces + Senses both atrium + ventricle, intrinsic cardiac activity inhibits pacer d/c, no activity: trigger d/c
DDDRAs above but adds rate responsiveness to
allow for exercise
RATE RESPONSIVE PACING
When the need for oxygenated blood increases, the pacemaker ensures that the heart rate increases to provide additional cardiac output
Adjusting Heart Rate to Activity
Normal Heart Rate
Rate Responsive PacingFixed-Rate Pacing
Daily Activities
DETERMINING TYPE OF PACEMAKER
Wallet card: 5 letter code
CXR: code visible
Single lead in ventricle: VVI
Separate leads DDD or DVI
SINGLE CHAMBER
VVI - lead lies in right ventricle
Independent of atrial activity
Use in AV conduction disease
DUAL CHAMBER
Typically in pts with nonfibrillating atria and intact AV conduction
PACEMAKER INTERVENTIONS
Magnet applicationNo universal function of magnetModel-specific magnet, some activate reed
switch asynchronous pacing at pre-set rate
Interrogation / ProgrammingModel-specific pacemaker programmer can
non-invasively obtain data on function and reset parameters
COMPLICATIONS OF PACEMAKER IMPLANTATION
COMPLICATIONS OF PACEMAKER IMPLANTATION Venous access Infection Thrombophelbitis Pacemaker Syndrome
VENOUS ACCESS
Bleeding Pneumo / haemothorax Air embolism
INFECTION 2% for wound and ‘pocket’ infection 1% for bacteremia with sepsis S. aureus and S. epidermidisRx : If bacteremic: start antibiotics, remove
system, new system to be placed
THROMBOPHLEBITIS Incidence 30-50% b/c of collateralization only 0.5-3.5%
devp symptoms Swelling, pain, venous engorgement Rx Heparin, lifetime warfarin
PACEMAKER SYNDROME Presents with worsening of original
symp post-implant of single chamber pacer
- hypotension, syncope,vertigo, exercise intolerance etc
AV asynchrony retrograde VA conduction atrial contraction against closed MV + TV jugular venous distention + atrial dilation sx of CHF
Rx : dual chamber pacer
Pacemaker syndrome
PACEMAKER MALFUNCTION
4 BROAD CATEGORIES1. Failure to Output2. Failure to Capture3. Inappropriate sensing: under or over4. Inappropriate pacemaker rate
FAILURE TO OUTPUTabsence of pacemaker spikes despite
indication to pace dead battery fracture of pacemaker lead disconnection of lead from pulse
generator unit Oversensing Cross-talk: atrial output sensed by
vent lead
spikes not followed by a stimulus-induced complex
change in endocardium: ischemia, infarction, hyperkalemia, class III antiarrhythmics (amiodarone, bertylium)
FAILURE TO CAPTURE
Failure to sense or capture in VVI
INAPPROPRIATE SENSING: UNDERSENSINGPacemaker incorrectly misses an
intrinsic deoplarization paces despite intrinsic activity
Appearance of pacemaker spikes occurring earlier than the programmed rate: “overpacing”
may or may not be followed by paced complex: depends on timing with respect to refractory period
AMI, progressive fibrosis, lead displacement, fracture, poor contact with endocardium
UNDERSENSING Pacemaker does not “see” the intrinsic
beat, and therefore does not respond appropriately
Intrinsic beat not sensed
Scheduled pace delivered
VVI / 60
INAPPROPRIATE SENSING: OVERSENSINGDetection of electrical activity not of
cardiac origin inhibition of pacing activity
“underpacing” pectoralis major: myopotentials
oversensed
Electrocautery MRI
OVERSENSING
An electrical signal other than the intended P or R wave is detected
Marker channel shows intrinsic
activity...
...though no activity is present
VVI / 60
INAPPROPRIATE PACEMAKER RATE Rare reentrant tachycardia seen w/
dual chamber pacers Premature atrial or vent contraction
sensed by atrial lead triggers vent contraction retrograde VA conduction sensed by atrial lead triggers vent contraction etc etc etc
Tx: Magnet application: fixed rate, terminates tachyarrthymia,
reprogram to decrease atrial sensing
CAUSES OF PACEMAKER MALFUNCTION Circuitry or power source of pulse
generator Pacemaker leads Interface between pacing electrode
and myocardium Environmental factors interfering with
normal function
PULSE GENERATOR
Loose connectionsSimilar to lead fracture Intermittent failure to sense or pace
MigrationDissects along pectoral fascial planeFailure to pace
Twiddlers syndromeManipulation lead dislodgement
TWIDDLER’S SYNDROME
LEADS
Dislodgement or fracture (anytime) Incidence 2-3%Failure to sense or paceDiagnosed with CXR, lead impedance
Insulation breaksCurrent leaks failure to captureDiagnosed with measuring lead impedance
(low)
CARDIAC PERFORATION
Early or late Usually well tolerated
Asymptomatic inc’d pacing threshold, hiccups
Diagnosis : hiccups, pericardial friction rub CXR, Echo
ENVIRONMENTAL FACTORS INTERFERING WITH SENSING
MRIElectrocauteryArc weldingLithotripsyMicrowavesMypotentials from muscle
PSEUDOMALFUNCTION: HYSTERESIS Allows a lower rate between sensed
events to occur; paced rate is higher
Lower Rate 70 ppm Hysteresis Rate 50 ppm
47
ANAESTHESIA FOR INSERTION
MACTo provide comfortTo control dysrhythmiasTo check for proper function/capture
Have external pacer & Atropine readyContinuous ECG and peripheral pulse
monitoring
48
PACEMAKER INSERTION
TEMPORARY PACING METHODS Invasive (Direct) cardiac Pacing
Epicardial Stainless steel Teflon coated wires.
Endocardial Flow directed balloon electrodes Catheter with guidewire With PA catheter- Side port for ventricular pacing
Non Invasive (Indirect) Transcutaneous Pacing
Combined pacing, cardioversion and defibrillation with ECG monitoring in a single unit
Instituted quickly Safely by minimally trained person
CONT.. Disadvantages of transcutaneous pacing
Inability to obtain reliable capture in Emphysema Pneumothorax Morbid obesity
Difficulty with lead placement Surgical Field Patient position
Failure of TCP to preserve AV synchrony For patients with poor ventricular diastolic
function
TRANSESOPHAGEAL PACING Uses
Noninvasive electrophysiological studiesTermination of reentrant tachydysrhythmiasTemporary bradycardia pacing
DisadvantagesNot suitable for ventricular pacing Intact AV conduction is required
IMPLANTABLE CARDIOVERTER DEFIBRILLATOR
S
AUTOMATED IMPLANTABLE CARDIOVERTER DEFIBRILLATOR (AICD) Indications
Recurrent VT/VFNot responding to medical therapyPoor risk for surgical ablation
2/3rd patients still require medical therapy
High cost Survival rate is similar
54
SETTINGS
Gives a shock at 0.1-30 joules Usually 25 joulesTakes 5-20 seconds to sense
VT/VFTakes 5-15 seconds more to
charge 2.5-10 second delay before next
shock is administeredTotal of 5 shocks, then pausesIf patient is touched, may feel a
buzz or tingleIf CPR is needed, wear rubber
gloves for insulation
AICD IN SITU
ICD
PG assembly 2010
209 cc 120 cc 80 cc 80 cc 72 cc 54 cc
62 cc 49 cc 39.5 cc 39.5 cc 36 cc38 cc39.5 cc
Implantable Defibrillators (1989-2003)
PG assembly 2010
GENERIC DEFIBRILLATOR CODE DEVELOPED AS JOINT PROJECTS BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) - REVISED 2002
Position 1Shock chambers
Position 2Anti tachycardia pacing chambers
Position 3Tachycardia detection
Position 4Anti bradycardia pacing chambers
O = none O = none E = electrocardiogram
O = none
A = atrium A = atrium H = haemodynamic
A = atrium
V = Ventricle V = ventricle V = ventricle
D = dual (A+ V) D = dual (A + V)
D = dual (A + V)
SURGICAL TECHNIQUES Non thoracotomy (More common)
Fluoroscopically Transvenous Monitored anesthesia care. General anesthesia- if repeated induction of
arrhythmia. Thoracotomy ( For Pediatric patients- epicardial
leads)Median sternotomyLeft thoracotomySubxiphoid approachSubcostal approach
61
ANESTHESIA
MAC vs GeneralUsually general due to induction of
VT/VF so AICD can be checked for performance
Lead is placed in heart
Generator is placed generally in upper chest
ASA PRACTICE ADVISORY FOR PERI OPERATIVE MANAGEMENT OF PATIENTS WITH CARDIAC IMPLANTABLE ELECTRONIC DEVICES
PRE OPERATIVE EVALUATIONA. Establish whether a patient has a
cardiac rhythm management device (CIED).
1. Conduct a focused history (patient interview, medical records review, and review of available chest x-rays, electrocardiograms, or any available monitor or rhythm strip information).
2. Conduct a focused physical examination (check for scars and palpate for device).
3. Define the type of CIED.
a. Obtain manufacturer’s identification card from patient or other source.
b. Order chest x-ray if no other data are available.
B. Determine the dependence on pacing function of the CIED.
1. Patient has history of symptomatic bradyarrhythmia resulting in CIED implantation.
2. Patient has history of successful atrioventricular nodal ablation.
3. Patient has inadequate escape rhythm at lowest programmable pacing rate.
C. Determine CIED function.
1. Interrogate device (consultation with a cardiologist or pacemaker-ICD service may be necessary).
2. Determine whether the device will capture when it paces (i.e., produce a mechanical systole with a pacemaker impulse).
PRE OPERATIVE PREPERATIONA. Determine whether EMI (electromagnetic
interference) is likely to occur during the planned procedure.
The pacemeker senses cautery signal as electrical activity, & may be inhibited causing asystole.
In case of ICD, it may sense cautery as ventricular fibrillation and deliver a shock.
1. Determine whether reprogramming pacing function to asynchronous mode or disabling rate responsive function is advantageous.
2. Suspend antitachyarrhythmia functions if present.
3. consider use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel.
4. Temporary pacing and defibrillation equipment should be immediately available
INTRA OPERATIVE MANAGEMENT
Monitor operation of the CIED.
1. Conduct electrocardiographic monitoring per ASA standard.
2. Monitor peripheral pulse (e.g., manual pulse palpation, pulse oximeter plethysmogram, and arterial line).
3. Pacemaker is not an indication for insertion of pulmonary artery & central venous catheter.
INDUCTION & MAINTENANCE Narcotics & inhalational agents can be
used successfully.
Succinylcholine fasciculations can inhibit stimulation and hence should be avoided.
Etomidate & ketamine should be avoided : cause myoclonic movements
Cases of pacemeker dislodgement by IPPV
Nitrous oxide entrapment in pacemeker pocket.
Factors that increase pacing threshold:
- Acidosis / alkalosis- Hypothermia- Hyperkalemia- Hypoglycemia- Severe hypoxia- Hypothyroidism- Myocardial ischemia/ infarction
ELECTROCAUTERY
1.Assure that electrosurgical receiving plate is positioned so the current pathway does not pass through or near the CIED system. It placed on a site different from the thigh (e.g., the superior
posterior aspect of the shoulder contralateral to the generator position for a head and neck case).
2. Avoid proximity of the cautery’s electrical field to the pulse generator or leads.
3. use short, intermittent and irregular bursts at the lowest feasible energy levels.
4. consider the use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel in place of a monopolar electrocautery system if possible
RADIOFREQUENCY ABLATION1. Avoid direct contact between the
ablation catheter and the pulse generator and leads.
2. keep the RF’s current path as far away from the pulse generator and lead system as possible.
LITHOTRIPSY1. Avoid focusing the lithotripsy beam
near the pulse generator.
2. If the lithotripsy system triggers on the R-wave, consider preoperative disabling of atrial pacing.
MAGNETIC RESONANCE IMAGING1. MRI is generally contraindicated in
patients with CIEDs.
2. If an MRI must be performed, consult with the ordering physician, the patient’s cardiologist, the diagnostic radiologist, and the CIED manufacturer.
RADIATION THERAPY
1. Radiation therapy can be safely performed in patients who have CIEDs.
2. Surgically relocate the CIED if the device will be in the field of radiation.
EMERGENCY DEFIBRILLATION OR CARDIOVERSION
A . terminate all sources of EMI while the magnet is removed.
b. Remove the magnet to reenable antitachycardia therapies.
c. If the above activities fail to restore ICD function, proceed with emergency external defibrillation or cardioversion.
FOR EXTERNAL DEFIBRILLATION
a. Position defibrillation/cardioversion pads or paddles as far as possible from the pulse generator.
b. Position defibrillation/cardioversion pads or paddles perpendicular to the major axis of the CIED to the extent possible by placing them in an anterior-posterior location.
c. If it is technically impossible to place the pads or paddles in locations that help to protect the CIED, then defibrillate/cardiovert the patient in the quickest possible way and be prepared to provide pacing through other routes.
POST OPERATIVE MANAGEMENTA. Continuously monitor cardiac rate and
rhythm and have back-up pacing and defibrillation equipment immediately available throughout the immediate postoperative period.
B. Interrogate and restore CIED function in the immediate postoperative period.
1. Interrogate CIED; consultation with a cardiologist or pacemaker-ICD service may be necessary.
2. Restore all antitachyarrhythmic therapies in ICDs.
3. Assure that all other settings of the CIED are appropriate