DEFIBRILLATOR, PACEMAKERS

AND ICDPresented by: rashmi bhatt

Moderator: dr dara negi

OBJECTIVES Principle of defibrillator Defibrillator vs cardioversion Principle and working of pacemaker Anesthetic implications Functioning of ICD Anesthetic implications of ICD

DEFIBRILLATION

Non synchronised delivery of energy during any phase of the cardiac cycle

Indications : VT, VF, cardiac arrest due to or resulting in these

Avoided in dysarrythmias d/t digitalis toxicity or catecholamine induced overactivity

Generally under induction or sedation unless patient is hemodynamically unstable

Hand held paddles considered better than self adhesive electrodes

DEFIBRILLATOR Types : AED, semi automated,standard

with monitor and implantable Positioning: anterolateral and

anteroposterior Anterolateral: left 4/5 ICS in midaxillary

line and right sternal edge in 2/3 ICS Anteroposterior: right sternal edge 2/3

ICS and b/w tip of left scapula and spine Anteropost is more effective for AF and

preferred in pts with implantable devices

ENERGY SELECTION Energy wave forms: monophasic and biphasic Biphasic: truncated and rectilinear Biphasic is more effective and uses lesser energy Atrial flutter: 25-50 J; AF: 50-100 J in stable

patients Polymorphic VT(unstable) or VF: 200-360 J Monomorphic VT(stable): 100-200 J In pediatric patients: 0.5J/kg Complications: arrythmias(VF),

thromboembolism(esp in AF), myocardial necrosis, ST elevation ( for upto 2 min), painful skin burns,hypoxia and rarely pulm oedema. Also injuries to the health care personnel.

CARDIOVERSION Delivery of energy is synchronised to the large R

waves or the QRS complexes Indications: SVT, AF, atrial flutter, vent tachy,

reentrant tachy with hemodynamic instability Synchronization is in the early part of QRS Internal cardioversion: preceded by anticoagulation.

Three temp catheters are inserted under fluoroscopic guidance. Two are used to deliver the shock and the third for R wave synchronisation and pacing.

1st in distal coronary sinus, 2nd in rt atrium appendix or lateral wall, both being connected to external defibrillator. 3rd(quadripolar) in apex of rt ventricle, connected to external pacemaker. Energy delivered is 5.6+-4.7 J.

PACEMAKER Temporary or permanent Consists of an impulse generator and lead(s) Leads could be transvenous or epicardial in

position, uni, bi or mutipolar in no of electrodes Unipolar: more sensitive to EMI, gas

interference Bipolar uses less energy and more resistant to

interference Placement could be transthoracic, transvenous

or transesophageal

CONVENTIONAL PACEMAKER

GENERIC CODE FOR PACEMAKER(NBG)POSITION 1 Pacing chamber(s)

POSITION 2 sensing chamber(s)

POSITION 3 response(s) to sensing

POSITION 4 programmability

POSITION 5 multisite pacing

O=none O= none O= none O= none O= none

A= atria A= atria I= inhibited

R= rate modulation

A= atria

V= ventricle

V= ventricle

T= triggered

V= ventricle

D=dual(A+V)

D=dual(A+V)

D=dual(I+T)

D=dual(A+V)

Indications: sinus node disease, av node disease, long QT syndrome, HOCM, DCM

Magnet behaviour: not all devices are sensitive

Magnet response: IFI/ERI/EOL Some pacemakers carry out TMT Pacemaker induced tachycardia

ANAESTHETIC IMPLICATIONS Pre op: optimise coexisting diseases, CXR,

reprogramming (to prevent oversensing). Spl considerations in lithotripsy, hysteroscopy, chest/abd procedures, TURP,ECT etc.

intraop: ecg filtering disabled, avoid monopolar ESU, equipment for pacing, defibrillation to be ready.

Post op: reprogramming and reinterrogation. Pacemaker failure: generator failure, lead failure,

failure of capture Failure of capture may result from increase in the

threshold for capture Correction by magnet application, temporary pacing,

sympathomimetic drugs(epi/dopa).

IMPLANTABLE CARDIOVERTER- DEFIBRILLATOR Important to differentiate from other

thoracic devices esp pacemaker in v/o electromagnetic interference(EMI)

Previously placed in an abdominal pocket; present day pectoral placement

Can be differentiated using a CXR to examine the RV lead system.

Other devices could be for pain control, thalamic stimulation to control PD, phrenic nerve stimulation, vagus stimulation for epilepsy, depression, heart failure and obesity.

DEFIBRILLATOR

Battery powered device to deliver energy in form of shock to terminate VT/VF

Believed to be superior to drug therapy in pt with EF<35%

Average life of 3-6 years Principle: measures R-R interval and categorises

as normal, fast or slow. Programmed to confirm VT/VF to avoid

inappropriate therapy(mc SVT) Delivers 6-18 shocks per minute Programmed to diff VT from SVT by onset,

stability, QRS width, AV synchrony and waveform In case of slow R-R, antibradycardia pacing

GENERIC CODE FOR ICD (NBD)

Position I: Shock Chambers(s)

Position II: Antitachycardia Pacing Chamber(s)

Position III: Tachycardia Detection

Position IV: Antibradycardia Pacing Chamber(s) *

O= none O= none E= electrogram

A= atrium A= atrium H= hemodynamic

A= atrium

V= ventricle V= ventricle V= ventricle

D= dual (A + V)

D= dual (A + V)

D= dual (A + V)

TECHNIQUES OF ICD PLACEMENT

Tranvenous or endocardial approach Surgical or Epicardial approach

Indications: vent tachy, vent fib, pts awaiting heart transplant, long QT syndrome, brugada syndrome, RV dysplasia.

Prophylactic role in HOCM, post MI with EF<30%

Magnet behaviour: suspension pf antitachycardia pacing. Generally no effect on antibradycardia pacing.

ANAESTHETIC IMPLICATIONS Pre op: optimisation of coexisting

conditions checking of battery life disable antitachycardia therapy CXR to confirm position of RV

lead Intra op: ecg monitoring facility to deliver external

cardioversion/defibrillation Post op: reinterrogation and reenabling

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