Pacemakers

Consists of:

1. Pulse generator (power source) 2. Pacing leads (insulated wires used to carry an electrical impulse from the pulse generator to the patient's heart, also carries information about the heart's electrical activity back to the pacemaker). The pacemaker then responds to the information received either by sending a pacing impulse to the heart (triggering) or by not sending a pace impulse to the heart (inhibition).

Ok so basically...

A single-chamber pacemaker has one lead in either the R atrium or R ventricle. A dual-chamber pacemaker has two leads, in both the R atrium and R ventricle. Multisite pacemakers have three or more leads and is either biatrial (more than one pacing site in the atrium) or biventricular (more than one pacing site in the ventricle)

A dual-chamber pacemaker may also be called a DDD pacemaker, indicating that:

Both the atrium and ventricle are paced (D) Both chambers are sensed (D) And the pacemaker has both a triggered and inhibited mode of response (D)

Post-op cares for new pacemaker or ICD

Monitor for bleeding/hematoma Monitor EKG to assess for appropriate pacemaker function because leads can become dislodged Patient education

Indications for ICD

Secondary prevention for survivors of cardiac arrest due to VT/VF Primary prevention for those at high risk for VT/VF (i.e., inherited prolonged QT syndrome, or heart failure)

The ventricular demand (VVI) pacemaker is a common type of pacemaker. With this device...

The pacemaker electrode is placed in the R ventricle (v) The ventricle is sensed (v) And the pacemaker is inhibited (I) when spontaneous ventricular depolarization occurs within a preset interval. When spontaneous ventricular depolarization does not occur within this preset interval, the pacemaker fires and stimulates ventricular depolarization at a preset rate.

A cardiac pacemaker is a

batter-powered device that delivers an electrical current to the heart to stimulate depolarization. Consists of a pulse generator (power source) and pacing leads (insulated wires used to carry an electrical impulse from the pulse generator to the patient's heart

Complications of permanent pacing associated with the implantation procedure include:

bleeding, local tissue reaction, pneumothorax, cardiac dysrhythmias, air embolism, and thrombosis.

*Second letter The second letter of the code identifies the

chamber of the heart where patient-initiated (i.e., intrinsic) electrical activity is sensed by the pacemaker.

Transvenous pacemakers stimulate the

endocardium of the right atrium or ventricle (or both) by means of an electrode introduced into a central vein, such as the subclavian, femoral, brachial, internal jugular, or external jugular vein. Complications include bleeding, infection, pneumothorax, cardiac dysrythmias, MI, lead discplacement, fracture of the pacing lead, hematoma at the insertion site, perforation of the right ventricle with or without pericardial tamponade, and perforation of the inferior vena cava, pulmonary artery, or coronary arteries because of improper placement of the pacing lead. Basically the pacing electrode is advanced through a large vein into the R atrium or R ventricle or both. You can use a Swanz-Ganz pacing pulmonary artery catheter.

*First letter The first letter of the code identifies the

heart chamber (or chambers) paced (stimulated).

Long-term complications of permanent pacing may include:

infection, electrode displacement, heart failure, fracture of the pacing lead, pacemaker-induced dysrhythmias, externalization of the pacemaker generator, and perforation of the right ventricle with or without pericardial tamponade.

ICD complications:

-Infections -Inappropriate shocks **contact device manufacturer's programmer** *Often due to lead fracture *Strong magnet (donut magnet) will temporarily turn off cardioversion/defibrillation function BUT contact manufacturer first! -Failure to shock or ineffective cardioversion

Now let's talk about pacemaker identification codes

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Ok, so now let's talk about temporary pacemakers

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ICD 4 functions:

1. Anti-tachycardic pacing (In most cases of ventricular tachycardia the ICD can restore normal heart rhythm with painless pacing therapy). 2. Cardioversion (If dysrhythmia continues, the ICD automatically delivers low-energy synchronized shocks. Mild discomfort. 3. High-energy defibrillation (High-energy shock therapy for ventricular fibrillation, designed to stop the heart and instantly reset the rhythm. This feels like a sudden "kick in the chest." 4. Newer ICD models also function as a bradycardia pacemaker (ICD-B).

More patient and caregiver teaching from Page 806 table 36-13

1. Maintain follow-up care w/ your cardiologist to begin regular pacemaker function checks. 2. Report any signs of infection at incision site (redness, swelling, drainage) or fever to your cardiologist immediately. 3. Keep incision dry for 4 days after implantation, or as ordered. 4. Avoid lifting arm on pacemaker side above shoulder until approved by your cardiologist. 5. Avoid direct blows to pacemaker site. 6. Avoid close proximity to high-output electrical generators, since these can interfere with the function of the pacemaker. 7. You should not have an MRI scan unless the pacemaker is approved as MRI safe or there is a protocol in place for patient safety during the procedure. 8. Microwave ovens are safe to use and do not interfere with pacemaker function. 9. Avoid standing near anti-theft devices in doorways of department stores and public libraries. You should walk through them at a normal pace. 10. Air travel is not restricted. Inform airport security of presence of pacemaker because it may set off the metal detector. If hand-held screening wand is used, it should not be placed directly over the pacemaker. Manufacturer information may vary regarding the effect of metal detectors on the function of the pacemaker. 11. Monitor pulse and inform cardiologist if it drops below the predetermined rate. 12. Carry pacemaker information card and a current list of your medications at all times. 13. Obtain and wear a Medic Alert ID or bracelet at all times.

The pacemaker can malfunction in the following three ways:

1. failure to sense/undersensing 2. failure to pace 3. failure to capture

The pacemaker has three functions:

1. sense (the pacemaker must recognize and respond to intrinsic cardiac depolarization) 2. pace (the pacemaker must send an electrical impulse to the myocardium) 3. capture (the pacing stimulus must depolarize the chamber being paced)

Indications for a permanent pacemaker and an Implantable Cardioverter Defibrillator (ICD)

2nd or 3rd degree AV block SA node dysfunction (symptomatic bradycardia or sick sinus syndrome) AFib with very slow ventricular response Congenital heart defect Heart failure

A pacemaker used to pace only a single chamber is represented by either

A (atrial) or V (ventricular)

Fixed-rate or asynchronous pacing

A pacing stimulus is delivered at a set or fixed rate regardless of the occurrence of spontaneous myocardial depolarization.

Synchronous (demand) pacing

A pacing stimulus is delivered only when the heart's intrinsic pacemaker fails to function at a predetermined rate.

Failure to pace

Absence of pacing spikes and no heart response. Can be due to: -Battery failure -Lead fracture or dislodgement -In transcutenous pacing this could be poor electrode-skin contact

What to teach patient who has a new pacemaker or ICD

Avoid lifting operative side arm above shoulder level for 1-2 weeks Keep incision dry for 4-7 days Report any signs of infection at incision site or fever Take pulse daily for 1 week than at least once weekly Avoid lifting more than 10lbs for 6-8 weeks Carry pacemaker information card at all times

A pacemaker capable of pacing in both chambers is represented by

D (dual).

Failure to capture

Failure of the pacing stimulus to depolarize the myocardium. EKG shows a pacer spike without evidence of depolarization. Can be due to: -Battery failure -Lead fracture or dislodgement -Milliamps (mA) needs to be increased due to inflammation or fibrosis

ICD support:

Patients should contact their clinic if their ICD fires, a shock from ICD is painful. A shock from ICD is painful, some patients require psychological support for anxiety. State laws vary on driving restrictions, most require no driving until shock free for 6 months. Electromagnetic field safety, same as pacemaker.

A permanent pacemaker is used to treat disorders of the

SA node (bradycardias), AV conduction pathways (second and third degree blocks) or both, that produce s/s as a result of inadequate cardiac output. The pacemaker's pulse generator is usually implanted under local anesthesia into the subcutaneous tissue of the anterior chest just below the right or left clavicle. The patient's handedness, occupation, and hobbies determine whether the pacemaker is implanted on the right or left side.

Failure to sense

The pacemaker does not recognize intrinsic beats and generates unnecessary pacemaker spikes. Can be due to: -Battery failure or lead dislodgement -Pacemaker sensitivity setting is too low or too high

A pacemaker system may be single or dual chamber. A single-chamber pacemaker is a pacemaker that paces

a single heart chamber, either the atrium or the ventricle, and has one lead placed in the heart.

Pacemaker codes are used to

assist in identifying a pacemaker's programmed pacing, sensing, and response functions.

The fourth letter of the code identifies the

availability of rate modulation (the pacemaker's ability to adapt its rate to meet the body's needs caused by increased physical activity and then increase or decrease the pacing rate accordingly).

An artificial pacemaker can be __________________ or __________________.

external (a temporary intervention) or implanted An external pacemaker may be used to control transient disturbances in heart rate or conduction that result from drug toxicity or that occurs during an MI, or following cardiac surgery when increased vagal tone is often present. Patients who have chronic dysrhythmias that are unresponsive to medication therapy and that result in decreased cardiac output may require the surgical implantation of a permanent pacemaker or ICD.

The pulse generator of a temporary pacemaker is located

externally. Temporary pacing can be accomplished through transvenous, epicardial, or transcutaneous means.

Transcutaneous pacing delivers pacing impulses to the heart using

large electrodes that are placed onto the patient's chest. Also called temporary external pacing or non-invasive pacing. Monitor comfort level (adjust output mA to lowest level necessary to consistently capture the myocardium and administer analgesics or sedatives as needed). Monitor skin integrity under the electrodes.

The fifth letter denotes

multisite pacing

Epicardial pacing is the placement of pacind leads directly

onto the or through the epidcardium. Epicardial leads may be used when a patient is undergiong cardiac surgery and the outer surface of the heart is easy to reach. Pacing electrodes are sewn to the epicardium during cardiac surgery. To prevent microshock -wear gloves when handling pacing wires -cap or insulate pacing wires when not in use -keep wires dry -instruct patient not to manipulate pacing wires or pulse generator

The third letter of the code indicates how the

pacemaker will respond when it senses patient-initiated electrical activity.

Pacing, which is also called pacemaker firing, occurs when the

pacemaker's pulse generator delivers energy through the pacing electrode to the myocardium. Evidence of pacing can be seen as a vertical line or spike on the ECG.

An ICD is a

programmable device that can deliver a range of therapies including defibrillation, antitachycardia pacing (overdrive pacing), synchronized cardioversion, and bradycardia pacing, depending on the dysrhythmia detected and how the device is programmed. A physician determines the appropriate therapies for each patient. ICDs are now small enough to be surgically placed in the pectoral area. *During overdrive pacing, the pacemaker is set to pace at a rate faster than the rate of the tachycardia. After a few seconds, the pacemaker is stopped to allow the return of the heart's intrinsic pacemaker.

Pacemaker lead systems may consist of _____, ______, or ______ leads.

single, double, or triple

Capture is the

successful conduction of an artificial pacemaker's impulse through the myocardium, resulting in depolarization. Capture is obtained after the pacemaker electrode is properly positioned in the heart; with one-to-one capture, each pacing stimulus results in depolarization of the appropriate chamber. On the ECG, evidence of electrical capture can be seen as a pacemaker spike followed by an atrial or ventricular complex, depending on the cardiac chamber that is being paced.

Sensitivity is

the ability of the pacemaker to detect the heart's intrinsic electrical activity. When the sensitivity is low, the pacemaker can't sense the intrinsic activity of the heart. When the sensitivity is high the pacemaker can sense the intrinsic activity of the heart.

Output is

the amount of electrical current (milliamps mA) that will be delivered to the atria or ventricle to initiate depolarization.

Pacemakers and ICDs store information about the activities of the patient's heart, as well as information about the device itself, such as

the number of dysrhythmia episodes, provoking rhythm, dates of pacing, defibrillation, or both. The stored information is periodically retrieved and reviewed by the patient's physician and, if necessary, changes in the device's settings are made.

Rate is

the number of impulses that will be delivered to the heart per minute.

Dual-chamber pacemakers use

two leads, one in the right atrium and one in the right ventricle. Stimulates the right atrium and right ventricle simultaneously (first atrium, then ventricle) mimicking normal cardiac physiology and thus preserving the atrial contribution to ventricular filling (atrial kick). When spontaneous atrial depolarization does not occur within a preset interval, the atrial pulse generator fires and stimulates atrial depolarization at a preset rate. The pacemaker is programmed to wait, simulating the normal conduction through the AV node. If spontaneous ventricular depolarization does not occur within a preset interval, the pacemaker fires and stimulates ventricular depolarization at a preset rate.