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Moderator : Dr Manju Mani

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1 Moderator : Dr Manju Mani
Cardiac implantable electronic devices (CIED) : Pacemakers, Implantable CARDIoverter defibrillators (ICD) Moderator : Dr Manju Mani

2 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

3 pacemaker Device that provides electrical stimulation to cause cardiac contraction when intrinsic cardiac electrical activity is slow or absent

4 Pacemaker Functions Stimulate cardiac depolarization
Sense intrinsic cardiac function Respond to increased metabolic demand by providing rate responsive pacing

5 Indications for Pacemaker
Aquired AV block - 30 AV block Symptomatic bradycardia Asystole >3 sec or escape rhythm <40bpm Post op AV block not expected to resolve Neuromuscular disease with AV block - 20 AV block Permanent or intermittent symptomatic bradycardia Class I recommendations From Rosen

6 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

7 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

8 Pacemaker Components and Anatomy

9 Pacemaker Components Pulse Generator Electronic Circuitry Lead System

10 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

11 Electronic Circuitry Sensing circuit Timing circuit Output circuit

12 Lead System Bipolar 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 Both are ONE wire. Don’t confuse bipolar and unipolar leads with single chamber and dual chamber pacemakers. Unipolar prone to oversensing because Anode may pick up myopotenials from muscle or other extrinsic source

13 Bipolar + - current travels only a short distance between electrodes
small pacing spike: <5mm + Anode - Cathode

14 Unipolar + - current travels a longer distance between electrodes
larger pacing spike: >20mm + Anode - Cathode

15 Paced Rhythm Recognition
VVI / 60

16 Pacemaker Code DEVELOPED AS JOINT PROJECT BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) REVISED 2002 I Chamber Paced II Sensed III Response to Sensing IV Programmable Functions/Rate Modulation V Antitachy Function(s) P: Simple programmable V: Ventricle V: Ventricle T: Triggered P: Pace M: Multi- programmable A: Atrium A: Atrium I: Inhibited S: Shock D: Dual (A+V) D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S) The first letter refers to the chamber(s) being paced The second letter refers to the chamber(s) being sensed The third letter refers to the pacemaker’s response to a sensed event: T = Triggered D = Dual (inhibited and triggered*) I = Inhibited O = No response *In a single chamber mode, “triggered” means that when an intrinsic event is sensed, a pace is triggered immediately thereafter. In a dual chamber mode, “triggered” means that a sensed atrial event will initiate (trigger) an A-V delay. The fourth letter denotes the pacemaker’s programmability and whether it is capable of rate response: P = Simple Programmable (rate and/or output) M = Multiprogrammable (rate, output, sensitivity, etc.) C = Communicating (pacemaker can send/receive information to/from the programmer) R = Rate Modulation O = None Note that this sequence is hierarchical. In other words, it is assumed that if a pacemaker has rate modulation capabilities, “R”, that it also can communicate, “C”. The fifth letter represents the pacemaker’s antitachycardia functions: P = Pace D = Dual (pace and shock available) S = Shock O = None You may want to test the audience by having them describe different pacing modes. More modes and ECG strips are found in Module 2. O: None O: None O: None R: Rate modulating O: None S: Single (A or V) O: None

17 Common Pacemakers VVI Ventricular Pacing : Ventricular sensing; intrinsic QRS Inhibits pacer discharge VVIR As 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 DDDR As above but adds rate responsiveness to allow for exercise Biosensors --- most are vibrations sensors that increase HR in proportion to activity sensed, but can also have pH, venous temp, resp rate, QT interval, stroke volume, O2 sat, RA pressure sensors less commonly. Dual chamber pacing allows for atrial contribution to CO (up to 30% of CO)

18 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 Pacing Fixed-Rate Pacing Piezoelectric crystal that detects mechanical signals produced by movement, mechanical signals translate into electrical signals that increase rate of the pacemaker Daily Activities

19 Determining type of pacemaker
Wallet card: 5 letter code CXR: code visible Single lead in ventricle: VVI Separate leads DDD or DVI

20 Single Chamber VVI - lead lies in right ventricle
Independent of atrial activity Use in AV conduction disease

21 Dual Chamber Typically in pts with nonfibrillating atria and intact AV conduction

22 Pacemaker Interventions
Magnet application No universal function of magnet Model-specific magnet, some activate reed switch  asynchronous pacing at pre-set rate Interrogation / Programming Model-specific pacemaker programmer can non- invasively obtain data on function and reset parameters Magnet application Useful to test pacemaker function and battery life, especially if intrinsic HR > paced rate Pre-set paced rate dec’s w/ dec’g battery life Programmable functions include lower rate limit, upper rate limit, AV interval, energy output, refractory periods, blanking period (interval after d/c during which no signals are sensed), mode of function (e.g. A, V, or D), max atrial tracking rate (fastest atrial rate pacer will keep up with), vent pacing response, algorithm for tachycardia termination, sensing parameters

23 Complications of Pacemaker Implantation

24 Complications of Pacemaker Implantation
Venous access Infection Thrombophelbitis Pacemaker Syndrome

25 Venous Access Bleeding Pneumo / haemothorax Air embolism

26 Infection 2% for wound and ‘pocket’ infection
1% for bacteremia with sepsis S. aureus and S. epidermidis Rx : If bacteremic: start antibiotics, remove system, new system to be placed

27 Thrombophlebitis Incidence 30-50%
b/c of collateralization only % devp symptoms Swelling, pain, venous engorgement Rx Heparin, lifetime warfarin

28 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 Present w/ presyncope, syncope, orthostatic dizziness, lightheadedness, fatigue, lethargy, CP, neck fullness, other non-specific complaints Can get w/ dual chamber pacer if SA node rate > paced rate in pts w/ AV block

29 Figure A 12-lead ECG from a 63-year-old woman with recurrent syncope several months after implantation of a VVI pacemaker. The arrows show the retrograde P waves of 1:1 ventricular-to-atrial conduction that may be associated with a pacemaker syndrome. Pacemaker syndrome

30 Pacemaker Malfunction

31 4 broad categories Failure to Output Failure to Capture
Inappropriate sensing: under or over Inappropriate pacemaker rate

32 Failure to Output absence 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 Cross-talk = oversensing of pacemaker generated electrical activity E.g. vent lead senses atrial pacing spike  misinterprets as vent contraction  inhibits pacer d/c  skipped beat  dizziness / syncope

33 Failure to capture spikes not followed by a stimulus-induced complex
change in endocardium: ischemia, infarction, hyperkalemia, class III antiarrhythmics (amiodarone, bertylium)

34 Failure to sense or capture in VVI
Figure A 12-lead ECG with a lead-V1 rhythm strip from an 84-year-old man who returned to a pacemaker clinic with dizziness 11 years after implantation of a VVI pacemaker. Arrows show pacing artifacts continuing regularly (68/min) not sensing for the patient's intrinsic beats and not producing paced beats. The asterisks indicate the single incidence of ventricular capture by the pacemaker Failure to sense or capture in VVI

35 Inappropriate sensing: Undersensing
Pacemaker 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

36 Scheduled pace delivered Intrinsic beat not sensed
Undersensing Pacemaker does not “see” the intrinsic beat, and therefore does not respond appropriately Scheduled pace delivered Intrinsic beat not sensed VVI / 60

37 Inappropriate sensing: Oversensing
Detection of electrical activity not of cardiac origin  inhibition of pacing activity “underpacing” pectoralis major: myopotentials oversensed Electrocautery MRI

38 Oversensing VVI / 60 ...though no activity is present Marker channel shows intrinsic activity... An electrical signal other than the intended P or R wave is detected Oversensing will exhibit pauses in single chamber systems. In dual chamber systems, atrial oversensing may cause fast ventricular pacing without P waves preceding the paced ventricular events.

39 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

40 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

41 Pulse Generator Loose connections Migration Twiddlers syndrome
Similar to lead fracture Intermittent failure to sense or pace Migration Dissects along pectoral fascial plane Failure to pace Twiddlers syndrome Manipulation  lead dislodgement

42 Twiddler’s Syndrome

43 Leads Dislodgement or fracture (anytime) Insulation breaks
Incidence 2-3% Failure to sense or pace Diagnosed with CXR, lead impedance Insulation breaks Current leaks  failure to capture Diagnosed with measuring lead impedance (low) Fractures occur at sharp turns (pulse generator, entry into vein, in ventricle, most commonly occurring at the clavicle/first rib location Measure lead impedance w/ pacemaker programmer Insulation break like leaky garden hose

44 Cardiac Perforation Early or late Usually well tolerated
Asymptomatic  inc’d pacing threshold, hiccups Diagnosis : hiccups, pericardial friction rub CXR, Echo

45 Environmental Factors Interfering with Sensing
MRI Electrocautery Arc welding Lithotripsy Microwaves Mypotentials from muscle

46 Pseudomalfunction: Hysteresis
CorePace Module 4: Troubleshooting Pseudomalfunction: Hysteresis Allows a lower rate between sensed events to occur; paced rate is higher Hysteresis Rate 50 ppm Lower Rate 70 ppm Hysteresis provides the capability to maintain the patient’s intrinsic heart rhythm as long as possible, while providing back-up pacing if the intrinsic rhythm falls below the hysteresis rate. Because hysteresis exhibits longer intervals between sensed events, it may be perceived as oversensing.

47 Anaesthesia for insertion
MAC To provide comfort To control dysrhythmias To check for proper function/capture Have external pacer & Atropine ready Continuous ECG and peripheral pulse monitoring

48 Pacemaker Insertion

49 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

50 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

51 Transesophageal pacing
Uses Noninvasive electrophysiological studies Termination of reentrant tachydysrhythmias Temporary bradycardia pacing Disadvantages Not suitable for ventricular pacing Intact AV conduction is required

52 Implantable Cardioverter Defibrillators

53 Automated Implantable Cardioverter Defibrillator (aicd)
Indications Recurrent VT/VF Not responding to medical therapy Poor 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 joules
Takes 5-20 seconds to sense VT/VF Takes 5-15 seconds more to charge second delay before next shock is administered Total of 5 shocks, then pauses If patient is touched, may feel a buzz or tingle If CPR is needed, wear rubber gloves for insulation

55 AICD in situ

56 ICD

57 Implantable Defibrillators (1989-2003)
120 cc 209 cc 80 cc 80 cc 72 cc 54 cc 62 cc 49 cc 39.5 cc 39.5 cc 36 cc 39.5 cc 38 cc PG assembly 2010

58 PG assembly 2010

59 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 1 Shock chambers Position 2 Anti tachycardia pacing chambers Position 3 Tachycardia detection Position 4 Anti bradycardia pacing chambers O = none E = electrocardiogram A = atrium H = haemodynamic V = Ventricle V = ventricle D = dual (A+ V) D = dual (A + V)

60 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 sternotomy Left thoracotomy Subxiphoid approach Subcostal approach

61 Anesthesia MAC vs General Lead is placed in heart
Usually 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


A. 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).

64 3. Define the type of CIED. a
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.

65 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.

66 C. Determine CIED function. 1
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).

67 Pre operative preperation
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.

68 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

69 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.

70 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.

71 Factors that increase pacing threshold:
Acidosis / alkalosis Hypothermia Hyperkalemia Hypoglycemia Severe hypoxia Hypothyroidism Myocardial ischemia/ infarction

72 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.

73 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

74 Radiofrequency ablation
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.

75 lithotripsy 1. 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.

76 Magnetic resonance imaging
1. 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.

77 Radiation therapy 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.

78 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.

79 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.

80 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.

81 Post operative management
A. Continuously monitor cardiac rate and rhythm and have back-up pacing and defibrillation equipment immediately available throughout the immediate postoperative period.

82 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

83 Thank You

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