Anethesia and cardiac implantable electronic devices

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Anesthesia for patients with

Cardiac Implantable Electronic Device


WHAT IS MEANT BY CARDIAC IMPLANTABLE ELECTRONIC DEVICES?

Cardiac implantable electronic devices is a term that encompasses:

1) cardiac pacemakers for bradyarrythmias treatment.

2) implantable cardioverter-defibrillators (ICD) for tachyarrythmias treatment.3) cardiac resynchronization therapy (CRT) devices for systolic dysfunction complicating conduction delays


PERMANENT PACEMAKERS (PPM)

A permanent pacemaker (PPM)system consists of:

1. a "pulse generator” to generate the electric impulse

2. Leads and electrodes connecting the generator to the heart for sensing and pacing

It’s main function is to restore and maintain a cardiac rhythm and rate sufficient to meet the metabolic needs of the body, i.e. treatment of symptomatic bradyarrythmias.




INDICATIONS FOR (PPM)

1. At the level of the sinoatrial node: Sick sinus syndrome is the most common indication for permanent pacing. Carotid sinus hypersensitivity and exaggerated vasovagal attacks

2. At the level of tha atria: AF with slow ventricular response not responding to medical treatment.

3. Symptomatic chronotropic incompetence.4. Type II second degree AV block with symptoms

or wide QRS (>120 msec)5. Bifascicular block with symptoms or with type II

second degree heart block or post MI6. Third degree AV block.7. Congenital complete heart block or prolonged

QT interval 8. Post cardiac transplantation 9. Drug induced symptomatic bradycardia


The term “symptomatic bradycardia” is defined as a documented bradyarrhythmia that is directly responsible for the development of frank syncope or near-syncope, transient dizziness or light-headedness, and confusional states resulting from cerebral hypo- perfusion attributable to slow heart rate. Fatigue, exercise intolerance, and frank congestive heart failure may also result from bradycardia. Definite correlation of symptoms with a bradyarrhythmia is a requirement to fulfill the criteria of symptomatic bradycardia.


PACEMAKER MODE CODESTHE NORTH AMERICAN PACING AND

ELECTROPHYSIOLOGY/BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (NASPE/BPEG)

REVISED NBG CODE FOR PACING NOMENCLATURE


COMMONLY USED PACEMAKER MODES

1. Asynchronous mode: pace the heart at a fixed preset rate independent of any intrinsic cardiac electrical activity. They can be (AOO), (VOO), or (DOO). Theoretically they can induce ventricular fibrillation through the (R on T phenomenon).

2. Single chamber demand pacing: the most popular type is(VVI)in which the ventricle is only paced when the intrinsic heart rate drops below a preset rate. However, it can’t maintain the atrioventricular synchrony leading to the “pacemaker syndrome”


Patients with sick sinus syndrome and normal AV node and conducting system usually benefit from (AAI) mode.

3. Dual chamber sequential pacing: with 2 leads , the atrium is stimulated first then after an adjustable PR interval the ventricle is stimulated. Thus preserving the AV synchrony. It’s most common type is (DDD) or (DVI) which is used in patients with sinoatrial and conducting system abnormalities .

4. Rate adaptive pacemakers: mainly for patients with chronotropic incompetence.


IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR (ICD)

It is a small battery-powered electrical impulse generator that is implanted in patients who are at risk of sudden cardiac death (SCD) due to ventricular fibrillation and ventricular tachycardia. The device is programmed to detect cardiac tachy-arrhythmias and correct it by delivering a brief electrical impulse to the heart within 10-15 sec.It can also produce anti-bradycardia pacing and synchronized cardioversion.




INDICATIONS FOR (ICD’S)

1. Survivors of cardiac arrest due to VF/VT not resulting from reversible causes.

2. Spontaneous sustained VT with structural heart disease.

3. Syncope of undetermined origin in a patient with hemodynamically significant sustained VT/VF induced at electrophysiology study.

4. Ischemic cardiomyopathy with EF<35% at least 40 days post MI.

5. Ischemic and non-ischemic dilated cardiomyopathy with EF<35% and are NYHA class II or III.

6. Brugada syndrome and HOCM.7. Arythmogenic right ventricular dysplasia8. Patients awaiting cardiac transplantation


ICD acts by measuring each cardiac R-R interval and categorize the rate as normal, too fast (short R-R interval), or too slow (long R-R interval). When the device detects a sufficient number of short R-R intervals within a period of time it will begin an antitachycardia event. The internal computer will decide between antitachycardia pacing (less energy use, better tolerated by patient) or shock. If shock is chosen, an internal capacitor is charged.An ICD with antibradycardia pacing capability will begin pacing when the R-R interval is too long


ICD’S NASPE/BPEG CODING SYSTEM


CARDIAC RESYNCHRONIZATION THERAPY (CRT)

Cardiac resynchronization therapy (CRT) is a relatively new therapy for patients with symptomatic heart failure resulting from systolic dysfunction.CRT is achieved by simultaneously pacing both the left and right ventricles. Theoretically, biventricular pacing resynchronizes the timing of global left ventricular depolarization and as a result improves mechanical contractility and mitral regurgitation.This therapy has been shown to improve the symptoms of heart failure and overall quality of life in certain patients with severe symptoms that aren't controlled with medication.




INDICATIONS OF CRT

1. CRT is indicated for patients who have LVEF less than or equal to 35%, sinus rhythm, LBBB with a QRS duration greater than or equal to 150 ms, and NYHA class II, III, or ambulatory IV symptoms.

2. CRT can be useful for patients who have LVEF less than or equal to 35%, sinus rhythm, LBBB with a QRS duration 120 to 149 ms, and NYHA class II, III, or ambulatory IV symptoms.

3. CRT may be considered for patients who have LVEF less than or equal to 30%, ischemic etiology of heart failure, sinus rhythm, LBBB with a QRS duration of greater than or equal to 150 ms, and NYHA class I symptoms.


In response to abnormal heart rhythms, it may also provide the following therapies:

1. Pacing therapy for slow heart rhythms2. Defibrillation therapies for fast or

irregular heart rhythmsThere are two types of CRT devices: a CRT pacemaker (CRT-P) and a CRT defibrillator (CRT-D). CRT-D devices, like all defibrillators, have a pacemaker function in them. Both devices help to coordinate the heart’s pumping action and deliver pacing therapy for a slow heart rate. However, the CRT-D can also treat fast heart rhythms


PERIOPERATIVE MANAGEMENT


Once a patient is identified as having a cardiac implantable electronic device, certain points have to be

covered

• the cause (underlying pathology as ISHD, malignant arrhythmia, drug

intake, other co-morbid conditions for preoperative optimization)• When it was last checked (a comprehensive check by the programmer

at least once yearly for pacemakers and every 6 months for ICD &CRT)

• Cardiological consultation (to determine The type of the device

and program mode, Is it functioning properly ? Battery longevity?)• Obtain a copy of the cardiological interrogation of the

CIED.• Consider replacing any CIED near its elective

replacement period in a patient scheduled to undergo either a major surgery or surgery within25 cm of the generator.

• Identification and avoidance of any probable sources for intraoperative electromagnetic interference

• The device response to magnet placement


Preoperative Evaluation Establish whether a patient has a cardiac rhythm management

device (CIED). 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).

Conduct a focused physical examination (check for scars and palpate for device).

Define the type of CIED. Obtain manufacturer's identification card from patient or other source. Order chest x-ray if no other data are available. Refer to supplemental resources (e.g., cardiological consultation,

manufacturer's databases). Determine the dependence on pacing function of the CIED.

Patient has history of symptomatic bradyarrhythmia resulting in CIED implantation.

Patient has history of successful atrioventricular nodal ablation. Patient has inadequate escape ventricular rhythm at lowest programmable

pacing rate with VVI mode. Determine CIED function.

Interrogate device (consultation with a cardiologist or pacemaker-implantable cardioverter-defibrillator [ICD] service is necessary).

Determine whether the device will capture when it paces (i.e., produce a mechanical systole with a pacemaker impulse).


preoperative appropriate reprogramming is the safest way to avoid intraoperative problems, especially if monopolar diathermy will be used.

1. Program minute ventilation rate responsiveness off if present.

2. Program all rate enhancements and modulation off.

3. Consider increasing the pacing rate to optimize oxygen delivery to tissues for major cases.

4. Disable anti-tachycardia therapy if a defibrillator by shifting its mode to “monitor only”

5. In case of central line insertion, Preoperative CXR for CRT to confirm the position of the coronary sinus lead and deactivation of ICD.

6. Establish a rapport with the proceduralist to identify and minimize the intraoperative causes of electromagnetic interference.


Regarding pacemakers: Reprogramming the pacing mode to asynchronous, at a rate greater than the patient’s underlying rate, usually ensures that no over- or under-sensing from EMI will take place. However, setting a device to asynchronous mode has the potential to create a malignant rhythm, the “R on T phenomenon”


THE MAGNET…TO USE OR NOT TO USE??

Placement of a magnet over a generator might produce no change in pacing since NOT ALL PACEMAKERS SWITCH TO A CONTINUOUS ASYNCHRONOUS MODE WHEN A MAGNET IS PLACED. Also, not all models from a given company behave the same way. Magnet behavior can be altered or disabled via programming in many devices. only a magnet test or interrogation with a programmer can reveal current settings. Heart rhythm society recommends magnet placement to create asynchronous pacing when needed where the magnet behavior is known, appropriate for the patient, the patient is supine, the magnet can be observed, and access to the magnet is possible


SERUM POTASSIUM LEVEL

Preoperative serum potassium level should be correct in patients with CIED ONCE DETECTED as hyperkalemia can have deleterious effects on those patients through increasing the resting membrane potential to a more positive value thus increasing pacing and the risk of VT/VF.


INTRAOPERATIVE MANAGEMENT 1. Temporary pacing “transcutanuoes and transvenous”,

defibrillation equipment, and resuscitation drugs should be immediately available.

2. Availability of appropriate cardiac personnel.

3. Continues ECG and peripheral pulse monitoring.(disable the artifact filter and pacing mode of monitor)

4. Regional anesthesia can be used (caution if anticoagulant is used)

5. Better to avoid drugs that inhibit the SA or the AV nodes like dexmedetomidine or potent opiates.

6. Etomidate and ketamine can induce myoclonus

7. Succinylcholine could interfere with CEID by either elevating serum potassium level or inducing fasciculations “myopotentials” which are misinterpreted as cardiac electrical activity

8. some potent inhalational agents (isoflurane, sevoflurane, and desflurane) might exacerbate the long Q-T syndrome

9. Avoid N2O in recently implanted pacemakers.

10. Avoid intraoperative hyperventilation


ELECTROCAUTERY Assure that the electrosurgical receiving plate

is positioned so the current pathway does not pass through or near the CIED system.

Advise the individual performing the procedure to avoid proximity of the cautery's electrical field to the pulse generator or leads.

Advise the individual performing the procedure to use short, intermittent and irregular bursts at the lowest feasible energy levels.

Advise the individual performing the procedure to reconsider the use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel in place of a monopolar electrocautery system if possible.

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INTRAOPERATIVE DEFIBRILLATION AND CIED

Emergency defibrillation or cardioversion For the patient with an ICD and magnet-disabled therapies: Advise the individual performing the procedure to terminate all sources of EMI while the

magnet is removed. Remove the magnet to re-enable anti-tachycardiac therapies. Observe the patient and the monitors for appropriate CIED therapy for 10 seconds If the above activities fail to restore ICD function, proceed with emergency external

defibrillation or cardioversion. For the patient with an ICD and programming-disabled therapies:

Advise the individual performing the procedure to terminate all sources of EMI while the magnet is removed.

Re-enable therapies through programming if the programmer is immediately available and ready to be used.

Observe the patient and the monitors for appropriate CIED therapy for 10 seconds If the above activities fail to restore ICD function, proceed with emergency external

defibrillation or cardioversion. For external defibrillation:

Position defibrillation/cardioversion pads or paddles as far as possible from the pulse generator.

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.

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.

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POSTOPERATIVE CARE postoperative care should include transferal to the ICU, avoid postoperative shivering, pain, and a full telemetric check and re‐programming back to the original setting if preoperative re‐programming was required. Anti‐tachycardia therapies of implantable defibrillators should obviously be re‐programmed to their original settings.


Date post:	02-Jun-2015
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Anethesia and cardiac implantable electronic devices

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