Management of a patient with Pacemaker

Prepared by Salman Habeeb

What is a pacemaker?• A pacemaker (or artificial pacemaker) is a

medical device which uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart

History of pacemakers

• In 1838 Carlo Matteucci a Professor of Physics at the University of Pisa - discovered that an electric current accompanies each heartbeat.

• 1926- Dr. Albert Hyman created an electromechanical instrument which many believe may be the first successful pacemaker

• 1950 a Canadian electrical engineer - John Hopps paired with Dr. Wilfred Bigelow

• The new pacemaker was a great advancement but still had some shortcomings like large and heavy

• The externally placed electrode sent electric impulses great deal of pain for the patient.

• 1951-Dr. Paul Zoll a cardiologist from Boston The pacemaker used modern transistors but still was large, heavy and relied on AC power.

• In 1957 - A part time TV repairmen Earl Bakken.,developed a smaller pacemaker that could be worn around the neck

• Less pain for patients,he leads were surgically attached to the outside of the myocardium.

• In 1956 bekkan read an article related to amplification of sound

• He started to work on amplification of battery for the power to pacemaker

• Created pacemaker with mercury battery that supplied 9.4 volts and co founded medtronics company

• After these period with the size of pacemakers and the short battery life, the idea of implanting a pacemaker into a patient was unthinkable• Greatbatch -an electrical engineer

founded a implanting pacemaker

• Greatbatch joined with medtronics and created litium iodine battery that still using in pacemakers

• In 1958 Dr. Dr. Ake Senning and team done first succesful pacemaker implantation to a patient named “Arne larsson with stoke –adam syndrome

• There was some problems with pacemakers so he received 5 different lead systems and 22 pulse generators of 11 different models in his lifetime

• lived to be 86 years old dying in December 28 2001 of cancer.

• 1960s – demand pacemaker was developed • 1970- nuclear powred pacemaker battery

developed (plutonium) can last upto 20 years but due to radiation exposure and other complication withdrawn from industry

Types • Implantable pulse generators with

endocardial or myocardial electrodes for long-term or permanent use( permenant pacemakers)

2• External, miniaturized, transistorized, patient

portable, battery-powered, pulse generators with exteriorized electrodes for temporary transvenous endocardial or transthoracic myocardial pacing. (temporary pacemakers)

• 3. Console battery- or AC-powered cardiovertors, defibrillators, or monitors with high-current external transcutaneous for temporary pacing in asynchronous or demand modes, with manual or triggered initiation of pacing

what is a permenant pacemaker

• A permenant pacemaker is an electronic device, approximately the size of a pocket watch, that senses intrinsic heart rhythms and provides electrical stimulation when indicated

Indications (ACC/AHA/HRS Guidelines)

• Class I - The procedure should be performed• Class IIa – It is reasonable to perform the

procedure, but additional studies with focused objectives are needed

• Class IIb - The procedure may be considered, but additional studies with broad objectives are needed

• Class III - The procedure should not be performed; it is not helpful and may be harmful

Class I indications

• Sinus node dysfunction• Acquired atrioventricular block in adults• Chronic bifascicular block• After acute myocardial infarction• Hypersensitive carotid sinus syndrome

and neurocardiogenic syncope• After cardiac transplantation• Pacing to prevent tachycardia• Patients with congenital heart disease

Class IIa indications

• Sinus node dysfunction• Acquired atrioventricular block in adults• Chronic bifascicular block• Hypersensitive carotid sinus syndrome

and neurocardiogenic syncope• Patients with congenital heart disease• Pacing to prevent tachycardia• Permanent pacemakers that

automatically detect and pace to terminate tachycardia

Class IIb indications

• Sinus node dysfunction• Acquired atrioventricular block in adults• Chronic bifascicular block• After acute myocardial infarction• Hypersensitive carotid sinus syndrome

and neurocardiogenic syncope• After cardiac transplantation• Pacing to prevent tachycardia• Patients with congenital heart disease

Class III indications

• Asymptomatic first-degree AV block. • Asymptomatic type I second-degree

AV block at the supra-His (AV node) level or that which is not known to be intra- or infra-Hisian. 

• AV block that is expected to resolve and is unlikely to recur(e.g., drug toxicity, Lyme disease, or transient increases in vagal tone or during hypoxia in sleep apnea syndrome in the absence of symptoms

Parts of a pacemaker system

Pulse generator

• Lithium batteries lasting 6 years or more are used in most pacemakers.

• Nuclear powered pacemakers (Plutonium238 source) can last 20 years or more.

• It controls energy output, heart rate and pacing node.

Energy output

• It refers to the intensity of the electrical impulse delivered by the pulse generator to the myocardium.

• Measured in milliampers(M.A)• A setting of 1.5 MA usually is sufficient to

cause depolarization

Heart rate

• heart rate is usually set at70-80 beats/minute

PACEMAKER LEADS

• Pacemaker leads are electrical conductors (wires), covered with insulation. They transmit the electrical impulses from the pulse generator to the heart, and from the heart to the pulse generator.

• They will attach to the heart in different ways

Active fixation

• in active fixation a screw (also known as a helix) is used to fix the lead to the heart.

Passive fixation

• In passive fixation the lead has tines ,which are designed to engage the trabeculae on the inner surface of the heart

APPROACHES OF PACING

Single Chamber pacing

• With this device, 1 pacing lead is implanted in the right atrium or ventricle

Double chamber pacing

With this device, 2 pacing leads are implanted (1 in the right ventricle and 1 in the right atrium); this is the most common type of implanted pacemaker

cardiac resynchronization therapy [CRT])

• Biventricular pacing -With this approach, in addition to single- or dual-chamber right heart pacing leads, a lead is advanced to the coronary sinus for left ventricular epicardial pacing.

CONCEPTUAL BUILDING BLOCKS OF PACEMAKER FUNCTION

• Pacing refers to the regular output of electrical current, for the purpose of depolarizing the cardiac tissue in the immediate vicinity of the lead, with resulting propagation of a wave of depolarization throughout that chamber.

Sensing

• Sensing describes the response of a pacemaker to intrinsic heartbeats

• During heartbeat The heart’s intrinsic electrical activity (i.e. the P wave or QRS complex) transmits a small electrical current (a few millivolts), through the pacemaker leads, to the pulse generator. This current can be registered or sensed by the pacemaker circuitry

• sensing can be unipolar or bipolar Unipolar sensing detects electrical activity occurring between the tip of the lead, and the metal shell of the pulse generator Bipolar sensing detects the intrinsic electrical activity occurring between the tip electrode and the ring electrode of the lead

• The sensitivity setting is measured in millivolts and is initially set at about 2 to 5 mV

• If the sensitivity is set very high the generator will Fail to sense the heart’s intrinsic impulses it is called undersensing

• if the sensitivity set low, that allowing the generator to detect beats that occur at lower millivolt levels and detecting beats that are not actually occurring it is called oversensing

Inhibition of output

A pacemaker can be programmed to inhibit pacing if it senses intrinsic activity, or it can be programmed to ignore intrinsic activity and deliver a pacing stimulus anyway. If a pacemaker is set so that it can be inhibited by intrinsic beats

Pacing Threshold

• The threshold is the minimum amount of energy the pacemaker sends down the lead to initiate a heart beat.

Capture

• Electrical capture, is Cardiac depolarization and resultant contraction (atrial or ventricular) - Caused by pacemaker stimulus, is detected by examining an electrocardiogram

• Capture is both an electrical and a mechanical event

• Electrical capture –spike in ECG• Mechanical capture-pulse

Rate response

• Most of the pacemekers available today are rate responsive ,it have various sensors that will active while patient during activities and adjust the rate .

Triggered pacing

• This type of pacing is most often used in dual chamber pacemakers.

• Dual chamber pacemakers can be programmed to sense activity in one chamber (usually the atrium) and deliver a pacing stimulus in the other chamber (usually the ventricle) after a certain time delay. This is known as triggered pacing

PACING MODES

• North American Society for Pacing and Electrophysiology, and the British Pacing and Electrophysiology Group developed a standard code (the NASPE/BPEG Generic Code, known as the NBG Code)

Position and Letters

• Position 1: chamber being paced• V = ventricle• A = atrium• D = atrium and ventricle (dual)• O = no pacing.

• Position 2: chamber being sensed

• V = ventricle• A = atrium• D = atrium and ventricle (dual)• O = no sensing

Position 3: pacing response to a sensed beat

• I = inhibited• T D = inhibited or triggered (dual) depending

on the chamber• O = neither inhibited or triggered.

• Position 4: rate response or absence

• R = rate responsive• O = absence of rate response. (But this is

usually just omitted)

Example• VVI • Position 1 (v)-indicates that it will pace only in

the ventricle.• Position 2 – V indicates that it senses intrinsic

heartbeats only in the ventricle.• Position 3 – I indicates that the response to a

sensed heartbeat is inhibition of ventricular pacing.

• Position 4 – blank, indicating that it is not rate responsive

PROCEDURE

• Venous assess• subclavian vein, the cephalic vein, or (rarely)

the internal jugular vein or the femoral vein are selected.

• subclavian vein is typically accessed at the junction of the first rib and the clavicle

• a guide wire is advanced through the access needle, and the tip of the guide wire is positioned in the right atrium or the venacaval area under fluoroscopy.

• The needle is then withdrawn, leaving the guide wire in place

2.Creation of pocket

• A 1.5- to 2-inch incision is made in the infraclavicular area parallel to the middle third of the clavicle, and a subcutaneous pocket is created with sharp and blunt dissection where the pacemaker generator will be implanted

3.Placement of lead(s)

• Over the guide wire, a special peel-away sheath and dilator are advanced

• The guide wire and dilator are withdrawn, leaving the sheath in place

• A stylet (a thin wire) is inserted inside the center channel of the pacemaker lead to make it more rigid, and the lead-stylet combination is then inserted into the sheath and advanced under fluoroscopy to the appropriate heart chamber.

• ventricular lead is positioned before the atrial lead to prevent its dislodgment

• Once correct lead positioning is confirmed, the lead is affixed to the endocardium either passively with tines (like a grappling hook) or actively via a helical screw located at the tip

• Once the lead is secured in position, the introducing sheath is carefully peeled away, leaving the lead in place

• After the pacing lead stylet is removed, pacing and sensing thresholds and lead impedances are measured with a pacing system analyzer, and pacing is performed at 10 V to make sure that it is not causing diaphragmatic stimulation

• If a second lead is indicated, it is positioned in the right atrium via a second sheath, with the lead tip typically positioned in the right atrial appendage

Positioning of pulse generator

• When the leads have been properly positioned and tested and sutured to the underlying tissue, the pacemaker pocket is irrigated with antimicrobial solution, and the pulse generator is connected securely to the leads.

Completion and closure

• The incision is closed in layers with absorbable sutures and adhesive strips. Sterile dressing is applied to the incision surface. An arm restraint or immobilizer is applied to the unilateral arm for 12-24 hours to limit movement

Complications

• Access-related complications Bleeding• Hematoma• Phlebitis or thrombophlebitis of the vein• Local infection• Arterial injury or puncture• Hemothorax• Pneumothorax

• Catheter-related thrombosis (which may lead to pulmonary embolism)

• Air embolism• Dysrhythmias• Atrial wall puncture from guide wire (which may

lead to pericardial tamponade)• Lost guide wire• Anaphylaxis• Chylothorax (possible with left-side lead insertion

• Pocket-related complications• Lead-related complications• Pacemaker generator–related complications

Cardiac Resynchronization Therapy

• Cardiac resynchronization therapy (CRT), also referred to as biventricular pacing or multisite ventricular pacing, is a component of modern heart failure therapy for qualified patients

• there is a coronary sinus lead for left ventricular epicardial pacing is present

• This reduce ventricular dyssynchrony that is frequently present in patients with ventricular dilatation or conduction system defect.

Who need CRT

• a left ventricular ejection fraction less than 35%,

• a QRS duration longer than 120 msec, sinus rhythm,

• New York Heart Association (NYHA) functional class III or ambulatory class IV heart failure symptoms with optimal medical therapy.

BENEFITS TO HEART FAILURE PATIENTS

• Reduction in ventricular electromechanical delay• Improved ventricular function• Reduced metabolic costs• Improved functional mitral regurgitation• Favorable remodeling• Reduction of cardiac chamber dimensions• Improved exercise capacity

PROCEDURE

• CRT requires left ventricular lateral wall pacing, which is achieved by placement of an epicardial lead via the coronary sinus

• A guide wire is inserted through the catheter positioned in the coronary sinus and maneuvered to the target venous branch

• The guide wire and guide catheter are withdrawn, leaving the coronary sinus lead in place.

Implantable Cardioverter-Defibrillator( ICD)

• An implantable cardioverter-defibrillator (ICD) is a specialized device designed to directly treat a cardiac tachydysrhythmia

• ICDs have revolutionized the treatment of patients at risk for sudden cardiac death due to ventricular tachyarrhythmias

Indications for ICD

• secondary prophylaxis • primary prophylaxis.

Secondary prophylaxis

• An ICD is recommended as initial therapy in survivors of cardiac arrest due to VF or hemodynamically unstable VT.

Primary prophylaxis

TEMPORARY PACEMAKERS

• Temporary cardiac pacing involves electrical cardiac stimulation to treat a bradyarrhythmia or tachyarrhythmia until it resolves or until long-term therapy can be initiated

TYPES

-Invasive approach • Transvenous pacing • Epicardial pacing– Non invasive

• Transcutaneous pacing

• Medtronic’s Single Chamber Temporary External Pacemaker

• Medtronic’s Dual chamber Temporary External Pacemaker Model

Connection

• EITHER unipolar or bipolar electrode wires• OUT Of the several methods for temporary

pacing of the heart (transcutaneous, transvenous, transesophageal, transthoracic, and epicardial), transvenous and transcutaneous cardiac pacing are the most commonly used

TRANSVENOUS PACING

• Transvenous cardiac pacing can be used as a bridge to permanent pacing when permanent pacing is not available, when the pacing need is only temporary, or when further evaluation is required

INDICATIONS • Injury to the SA node or other parts of the conduction

system after cardiac Chest and cardiac trauma associated with either temporary SA node or AV node dysfunction

• Metabolic and electrolyte derangements (eg, hyperkalemia)

• Drug-induced bradyarrhythmia (eg, digitalis toxicity); if treatment with the drug must be continued and there is no alternative, permanent pacing should be considered

• Other diseases (eg, Lyme disease, bacterial endocarditis) that may be associated with temporary damage to the SA node or the AV node

PROCEDURE

• Venous access Local anesthesia internal jugular and subclavian common sites

Other sites

• Central Venous Access, Internal Jugular Vein, Anterior Approach, Tunneled

• Central Venous Access, Internal Jugular Vein, Posterior Approach

• Central Venous Access, Subclavian Vein, Subclavian Approach

• Central Venous Access, Subclavian Vein, Supraclavicular Approach

• Femoral Central Venous Access

Placement of pacing lead

• a semirigid pacing lead may be used• The lead is advanced until it reaches the RA• To reach the RV, the catheter is passed

through the tricuspid valve; this may be accomplished more easily if the clinician forms a loop in the atrium and rotates the catheter

• When the lead is in place, it is connected to the external generator, and the appropriate mode is selected

• In an emergency, the highest output should be tried first; it should then be gradually reduced until the capture is lost

If the situation is not an emergency,

• the rate is set 10-20 beats/min above the intrinsic heart rate

• the output is initially set very low and then gradually increased until capture occurs

• The output should be set to a value at least 2-3 times higher than the threshold to ensure a safe margin for any change that occurs in the capture threshold, which is usually less than 1 mA

• To check the sensing threshold (if it is needed in the demand pacing mode), the pacing rate should be set lower than the intrinsic heart rate

• The value of the sensing threshold should then be gradually increased until the pacemaker fails to sense the intrinsic activity and consequently begins firing

• The sensing threshold is usually more than 5 mV in the ventricle and is much lower in the atrium

• Confirmation of pacing lead position ECG,chest X ray

ECG changes

• A paced QRS should exhibit left bundle-branch block (LBBB) morphology because the lead is located in the right ventricle

• If the pacing lead is in the right ventricular outflow tract, the paced QRS complexes show LBBB morphology and an inferior axis (which might also be rightward)

• A pacing lead in the coronary sinus will show right bundle-branch block (RBBB) morphology

• Complications Sequelae of venous access Loss of capture and undersensing Oversensing Ventricular arrhythmia Myocardial perforation

EPICARDIAL PACING

• This type of pacing is initiated after cardiac surgery

• Indications for temporary epicardial pacing The main indication for insertion of epicardial pacing wires is perioperative arrhythmias

• bradycardia, • nodal or junctional arrhythmias • atrioventricular block

procedure

• Commonly single or double set of electrodes• Each elctrode contains positive and

negative(smaller)• Ventricular-left of sternum• Atrium – right to sternum

Insertion of ventricular pacing wires

• Left ventricular electrodes may be placed in the apex just to the left of the distal left anterior descending artery or along the obtuse margin

• Wires should be inserted into the bare muscular portion of the ventricle to ensure adequate myocardial contact

Removal of pacing wires

• Pacing wires are usually removed on the fourth postoperative day

Complications

• Bleeding from the site of insertion • Dislodgement and fracture of pacing wires • ventricular arrhythmias

TRANSCUTANEOUS PACING

• also called external pacing• accomplished by delivering pulses of electric

current through the patient's chest, which stimulates the heart to contract

Indications

• It can be used until permanent pacing becomes available

• is indicated primarily for the treatment of bradycardia and various types of heart block, intermittent overdrive pacing can also be used as an antitachycardic treatment for various atrial and ventricular tachycardias (eg, postoperative atrial flutter and monomorphic ventricular tachycardia)

• It is the pacing method of choice in patients who received thrombolytic therapy for acute myocardial infarction when the risk of bleeding from surgical incisions is high.

PROCEDURE

• Patient Preparation Anesthesia –patient may have pain so sedation by midazolam is used Positioning- remove the hair anterior electrode placed either over the cardiac apex or at the position of lead V3

• posterior electrode, positive polarity, placed inferior to the scapula or between the right or left scapula and the spine

• Turn the pacemaker on, and choose the pacing mode

• The demand mode is usually preferable and should be used initially

• the pacing threshold is usually less than 80 mA

NURSING MANAGEMENT

HEALTH EDUCATION

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