Pacemaker Therapy

*pacemaker spike. *

The line that represents pacing

dysrhythmia, underlying cardiac function, age.

The type of pacemaker generator and the settings selected depend on the patient's

Transcutaneous pacing & PULSELESS Bradycardia

Transcutaneous pacing is NOT indicated for pulseless bradycardia

*VVI in patients with sinus node dysfunction* (formerly called sick sinus syndrome),

- *most common cause of bradycardias requiring* *a pacemaker, and a functioning AV node *

The generator for biventricular pacing has 3 leads:

- for the right atrium; - for the right ventricle, as with most standard pacemaker generators; and - for the left ventricle, usually placed in the left lateral wall.

The following data should be noted on the patient's record:

-model of pacemaker, - type of generator, -date and time of insertion, - location of pulse generator, -stimulation threshold, -pacer settings (e.g., rate, energy output [mA], sensitivity [mV], -duration of interval between atrial and ventricular impulses [AV delay]). -This infor is important for identifying normal pacemaker function and diagnosing pacemaker malfunction.

Pacemaker Generator Functions

Because of the sophistication and wide use of pacemakers, a universal code has been adopted to provide a means of safe communication about their function. The coding is referred to as the *NASPE-BPEG* code because it is sanctioned by the North American Society of Pacing and Electrophysiology and the British Pacing and Electrophysiology Group. The complete code consists of 5 letters; the 4th & 5th letters are used only with permanent pacemakers The pacemaker *paces the atrium and THEN the* *ventricle when no ventricular activity* is sensed for a period of time (the time is individually programmed into the pacemaker for each patient). A *straight vertical line* usually can be seen on the ECG when pacing is initiated. The line that represents pacing is called a *pacemaker spike. * The appropriate ECG complex should immediately follow the pacing spike; therefore, a P wave should follow an atrial pacing spike and a QRS complex should follow a ventricular pacing spike. Because the impulse starts in a different place than the patient's normal rhythm, the QRS complex or P wave that responds to pacing looks different from the patient's normal ECG complex. *Capture* is a term used to denote that the appropriate complex followed the pacing spike. The type of pacemaker generator and the settings selected depend on the *patient's dysrhythmia,* *underlying cardiac function, and age.* Pacemakers are generally set to sense and respond to intrinsic activity, which is called *on-demand pacing* If the pacemaker is set to pace but not to sense, it is called a *fixed or asynchronous pacemaker* ; this is written in pacing code as *AOO or VOO. * The pacemaker paces at a constant rate, independent of the patient's intrinsic rhythm. *VOO* pacing may indicate battery failure. *VVI* (V, paces the ventricle; V, senses ventricular activity; I, paces only if the ventricles do not depolarize) pacing causes loss of AV synchrony and atrial kick, which may cause a decrease in cardiac output and an increase in atrial distention and venous congestion. *Pacemaker syndrome*, causing symptoms such as chest discomfort, shortness of breath, fatigue, activity intolerance, and postural hypotension, is *most common with VVI pacing* (Tracy et al., 2012). *Atrial pacing and dual-chamber* (right atrial and right ventricular) pacing have been found to reduce the incidence of atrial fibrillation, ventricular dysfunction, and heart failure *Single-chamber atrial pacing (AAI)* or *dual-chamber pacing (DDD)* is recommended over: *VVI in patients with sinus node dysfunction* (formerly called sick sinus syndrome), - *most common cause of bradycardias requiring* *a pacemaker, and a functioning AV node * *AAI* pacing ensures synchrony between atrial and ventricular stimulation (and therefore contraction), as long as the patient has no conduction disturbances in the AV node. *Dual-chamber* pacemakers are recommended as the treatment for patients with AV conduction disturbances

Complications of Pacemaker Use

Complications associated with pacemakers relate to their presence within the body and improper functioning (see Chart 26-8). In the initial hours after a temporary or permanent pacemaker is inserted, the most common complication is dislodgment of the pacing electrode. Minimizing patient activity can help prevent this complication . If a temporary electrode is in place, the extremity through which the catheter has been advanced is immobilized. With a permanent pacemaker, the patient is instructed initially to restrict activity on the side of the implantation. The ECG is monitored very carefully to detect pacemaker malfunction. Improper pacemaker function, which can arise from failure in one or more components of the pacing system, is outlined in Table 26-2. The following data should be noted on the patient's record: -model of pacemaker, - type of generator, -date and time of insertion, - location of pulse generator, -stimulation threshold, and -pacer settings (e.g., rate, energy output [mA], sensitivity [mV], and -duration of interval between atrial and ventricular impulses [AV delay]). This information is important for identifying normal pacemaker function and diagnosing pacemaker malfunction. A patient experiencing pacemaker malfunction may develop bradycardia as well as signs and symptoms of decreased cardiac output (e.g., diaphoresis, postural hypotension, syncope). The degree to which these symptoms become apparent depends on the severity of the malfunction, the patient's level of dependency on the pacemaker, and the patient's underlying condition. Pacemaker malfunction is diagnosed by analyzing the ECG. Manipulating the electrodes, changing the generator's settings, or replacing the pacemaker generator or leads (or both) may be necessary. Inhibition of permanent pacemakers or reversion to asynchronous fixed rate pacing can occur with exposure to strong electromagnetic fields (electromagnetic interference [EMI]). However, recent pacemaker technology allows patients to safely use most household electronic appliances and devices (e.g., microwave ovens, electric tools). Gas-powered engines should be turned off before working on them. Objects that contain magnets (e.g., the earpiece of a phone, large stereo speakers, jewelry) should not be near the generator for longer than a few seconds. Patients are advised to place digital cellular phones at least 6 to 12 inches away from (or on the side opposite of) the pacemaker generator and not to carry them in a shirt pocket. Large electromagnetic fields, such as those produced by magnetic resonance imaging, radio and television transmitter towers and lines, transmission power lines (not the distribution lines that bring electricity into a home), and electrical substations may cause EMI. Patients should be cautioned to avoid such situations or to simply move farther away from the area if they experience dizziness or a feeling of rapid or irregular heartbeats (palpitations). Welding and the use of a chain saw should be avoided. If such tools are used, precautionary steps such as limiting the welding current to a 60- to 130-ampere range or using electric rather than gasoline-powered chain saws are advised.

Commonly, *only the first three letters* are used for a pacing code. An example of an NASPE-BPEG code is *DVI:*

D: Both the atrium and the ventricle have a pacing electrode in place. V: The pacemaker is sensing the activity of the ventricle only. I: The pacemaker's stimulating effect is inhibited by ventricular activity—in other words, it does not create an impulse when the pacemaker senses that the patient's ventricle is active.

TABLE 26-2 Assessing Pacemaker Malfunction

In addition, the metal of the pacemaker generator may trigger store and library antitheft devices as well as airport and building security alarms; however, these alarm systems generally do not interfere with the pacemaker function. Patients should walk through them quickly and avoid standing in or near these devices for prolonged periods of time. The handheld screening devices used in airports may interfere with the pacemaker. Patients should be advised to ask security personnel to perform a hand search instead of using the handheld screening device. Patients also should be educated to wear or carry medical identification to alert personnel to the presence of the pacemaker.

Chart 26-8 Potential Complications from Insertion of a Pacemaker

Local infection at the entry site of the leads for temporary pacing, or at the subcutaneous site for permanent generator placement. Prophylactic antibiotic and antibiotic irrigation of the subcutaneous pocket prior to generator placement has decreased the rate of infection to a minimal rate. Pneumothorax; the use of sheaths marketed as "safe" reduces this risk. Bleeding and hematoma at the lead entry sites for temporary pacing, or at the subcutaneous site for permanent generator placement. This usually can be managed with cold compresses and discontinuation of antiplatelet and antithrombotic medications. Hemothorax from puncture of the subclavian vein or internal mammary artery. Ventricular ectopy and tachycardia from irritation of the ventricular wall by the endocardial electrode. Movement or dislocation of the lead placed transvenously (perforation of the myocardium). Phrenic nerve, diaphragmatic (hiccuping may be a sign), or skeletal muscle stimulation if the lead is dislocated or if the delivered energy (mA) is set high. The occurrence of this complication is avoided by testing during device implantation. Cardiac perforation resulting in pericardial effusion and, rarely, cardiac tamponade, which may occur at the time of implantation or months later. This condition can be recognized by the change in QRS complex morphology, diaphragmatic stimulation, or hemodynamic instability. Twiddler syndrome may occur when the patient manipulates the generator, causing lead dislodgement or fracture of the lead. Pacemaker syndrome (hemodynamic instability caused by ventricular pacing and the loss of AV synchrony).

nursing responsibility: PACEMAKER

Monitoring for pacemaker malfunctioning and battery failure Close monitoring of the respiratory status is needed until the patient is fully awake.

on-demand pacing

Pacemakers are generally set to sense and respond to intrinsic activity, which is called_____________

Pacemaker Design and Types- 2 COMPONENTS of Pacemaker

Pacemakers consist of two components: 1. electronic pulse generator 2. pacemaker electrodes, which are located on leads or wires.

Pacemaker Surveillance

Remote monitoring technology can now be embedded in the device that not only replaces the need for in-person follow up cardiologist visits, but it also is associated with improved survival ( In addition, with the ability to obtain ECG recordings with phone applications, which can then be sent to the primary provider at the cardiology clinic, the frequency of the in-person pacemaker checks varies significantly. Trans-telephonic transmission of the generator's information is a commonly utilized follow-up method. Special equipment is used to transmit information about the patient's pacemaker over the telephone to a receiving system at the cardiology clinic. The information is converted into tones; equipment at the clinic converts these tones to an electronic signal and records them on an ECG strip. The pacemaker rate and other data concerning pacemaker function (e.g., generator setting, battery status, sensing function, lead integrity, pacing data, such as number of pacing events) are obtained and evaluated by a cardiologist. This simplifies the diagnosis of a failing generator, reassures the patient, and improves management when the patient is physically remote from pacemaker testing facilities. A typical follow-up schedule is every 2 weeks during the first month, every 4 to 8 weeks for 3 years, and every 4 weeks thereafter.

Chart 26-7 North American Society of Pacing and Electrophysiology and the British Pacing and Electrophysiology Group Code (NASPE-BPEG Code) for Pacemaker Generator Function

The first letter of the code identifies the chamber or chambers being paced (i.e., the chamber containing a pacing electrode). The letter characters for this code are A (atrium), V (ventricle), or D (dual, meaning both A and V). The second letter identifies the chamber or chambers being sensed by the pacemaker generator. Information from the electrode within the chamber is sent to the generator for interpretation and action by the generator. The letter characters are A (atrium), V (ventricle), D (dual), and O (indicating that the sensing function is turned off). The third letter of the code describes the type of response that will be made by the pacemaker to what is sensed. The letter characters used to describe this response are I (inhibited), T (triggered), D (dual—inhibited and triggered), and O (none). Inhibited response means that the response of the pacemaker is controlled by the activity of the patient's heart—that is, when the patient's heart beats, the pacemaker does not function, but when the heart does not beat, the pacemaker does function. In contrast, a triggered response means that the pacemaker responds (paces the heart) when it senses intrinsic heart activity. The fourth letter of the code is related to a permanent generator's ability to vary the heart rate. This ability is available in most current pacemakers. The possible letters are O, indicating no rate responsiveness, or R, indicating that the generator has rate modulation (i.e., the pacemaker has the ability to automatically adjust the pacing rate from moment to moment based on parameters, such as QT interval, physical activity, acid-base changes, body temperature, rate and depth of respirations, or oxygen saturation). A pacemaker with rate-responsive ability is capable of improving cardiac output during times of increased cardiac demand, such as exercise and decreasing the incidence of atrial fibrillation. All contemporary pacemakers have some type of sensor system that enables them to provide rate-adaptive pacing. The fifth letter of the code has two different indications: (1) that the permanent generator has multisite pacing capability with the letters A (atrium), V (ventricle), D (dual), and O (none); or (2) that the pacemaker has an antitachycardia function. Commonly, only the first three letters are used for a pacing code. An example of an NASPE-BPEG code is DVI: D: Both the atrium and the ventricle have a pacing electrode in place. V: The pacemaker is sensing the activity of the ventricle only. I: The pacemaker's stimulating effect is inhibited by ventricular activity—in other words, it does not create an impulse when the pacemaker senses that the patient's ventricle is active.

Synchronized biventricular pacing,

also called cardiac resynchronization therapy (CRT), -has been found to modify the intraventricular, interventricular, and AV conduction defects identified with symptomatic moderate to severe left ventricular dysfunction and heart failure . CRT has also been implemented in patients with heart failure and atrial fibrillation and is associated with improved mortality rates The generator for biventricular pacing has 3 leads: one for the right atrium; one for the right ventricle, as with most standard pacemaker generators; and one for the left ventricle, usually placed in the left lateral wall. This therapy improves cardiac function, resulting in decreased heart failure symptoms and an improved quality of life. Biventricular pacing may be used with an ICD.

Permanent pacemaker generators

are insulated to protect against body moisture and warmth and have filters that protect them from electrical interference from most household devices, motors, and appliances. Lithium cells are most commonly used; they last approximately 6 to 12 years, depending on the type of pacemaker, how it is programmed, and how often it is used. Most pacemakers have an elective replacement indicator (ERI), which is a signal that indicates when the battery is approaching depletion . The pacemaker continues to function for several months after the appearance of ERI to ensure that there is adequate time for a battery replacement. Although some batteries are rechargeable, most are not. Because the battery is permanently sealed in the pacemaker, the entire generator must be replaced. To replace a failing generator, the leads are disconnected, the old generator is removed, and a new generator is reconnected to the existing leads and reimplanted in the already existing subcutaneous pocket. Sometimes the leads are also replaced. Battery replacement is usually performed using a local anesthetic. Hospitalization is necessary for implantation or battery replacement; the patient usually can be discharged that day or the next day. If a patient suddenly develops a bradycardia, is symptomatic but has a pulse, and is unresponsive to atropine, emergency pacing may be started with transcutaneous pacing, which most defibrillators are now equipped to perform. Some AEDs are able to do both defibrillation and transcutaneous pacing. Large pacing ECG electrodes (sometimes the same conductive pads used for cardioversion and defibrillation) are placed on the patient's chest and back. The electrodes are connected to the defibrillator, which is the temporary pacemaker generator (see Fig. 26-27). Because the impulse must travel through the patient's skin and tissue before reaching the heart, transcutaneous pacing can cause significant discomfort (burning sensation and involuntary muscle contraction) and is intended to be used only in emergencies for short periods of time. This type of pacing necessitates hospitalization. If the patient is alert, sedation and analgesia may be given. After transcutaneous pacing, the skin under the electrode should be inspected for erythema and burns. Transcutaneous pacing is not indicated for pulseless bradycardia

VVI pacing V, paces the ventricle; V, senses ventricular activity; I, paces only if the ventricles do not depolarize

causes loss of AV synchrony and atrial kick, which may cause: -decrease in cardiac output -increase in atrial distention and venous congestion.

Pacemaker syndrome: SYMPTOMS

chest discomfort, shortness of breath, fatigue, activity intolerance, postural hypotension, -is most common with VVI pacing

2 COMPONENTS of Pacemaker Generator & electrodes

contains the circuitry and batteries that determine the rate (measured in beats per minute) and the strength or output (measured in *milliamperes* [mA]) of the electrical stimulus delivered to the heart. The generator also has circuitry that can detect the intracardiac electrical activity to cause an appropriate response; this component of pacing is called sensitivity and is measured in *millivolts* (mV). Sensitivity is set at the level that the intracardiac electrical activity must exceed to be sensed by the device. Leads, which carry the impulse created by the generator to the heart, can be threaded by fluoroscopy through a major vein into the heart, usually the right atrium and ventricle (endocardial leads), or they can be lightly sutured onto the outside of the heart and brought through the chest wall during open heart surgery (epicardial wires). The epicardial wires are always temporary and are removed by a gentle tug a few days after surgery. The endocardial leads may be temporarily placed with catheters through a vein (usually the femoral, subclavian, or internal jugular vein [transvenous wires]), usually guided by fluoroscopy. The leads may also be part of a specialized pulmonary artery catheter However, obtaining a pulmonary artery wedge pressure may cause the leads to move out of pacing position. The endocardial and epicardial wires are connected to a temporary generator, which is about the size of a small paperback book. The energy source for a temporary generator is a common household battery. Monitoring for pacemaker malfunctioning and battery failure is a nursing responsibility. The endocardial leads also may be placed permanently, passed into the heart through the subclavian, axillary, or cephalic vein, and connected to a permanent generator. Most current leads have a fixation mechanism (e.g., a screw) at the end of the lead that allows precise positioning and avoidance of dislodgement. The permanent generator, which often weighs less than 1 oz and is the size of a large book of matches, is usually implanted in a subcutaneous pocket created in the pectoral region, below the clavicle, or behind the breast, especially in young women (see Fig. 26-26). This procedure usually takes about 1 hour, and it is performed in a cardiac catheterization laboratory using a local anesthetic and moderate sedation. Close monitoring of the respiratory status is needed until the patient is fully awake.

AAI pacing

ensures synchrony between atrial and ventricular stimulation (and therefore contraction), as long as the patient has no conduction disturbances in the AV node.

Atrial pacing and dual-chamber (right atrial and right ventricular) pacing

have been found to reduce the incidence of atrial fibrillation, ventricular dysfunction, and HF

pacemaker

is an electronic device that provides electrical stimuli to the heart muscle.

fixed or asynchronous pacemaker

is called if the pacemaker is set to pace but not to sense pacing code: AOO or VOO. The pacemaker paces at a constant rate, independent of the patient's intrinsic rhythm.

Pacemaker syndrome:

is most common with VVI pacing

VOO pacing

may indicate battery failure.

Single-chamber atrial pacing (AAI) or dual-chamber pacing (DDD)

recommended over *VVI in patients with sinus node dysfunction* (formerly called sick sinus syndrome), - *most common cause of bradycardias requiring* *a pacemaker, and a functioning AV node *

NASPE-BPEG code

refers to universal code used to provide a means of safe communication re: pacemaker function - it is sanctioned by the North American Society of Pacing and Electrophysiology and the British Pacing and Electrophysiology Group.

Dual-chamber pacemakers

treatment for patients with AV conduction disturbances

*Capture*

used to denote that the appropriate complex followed the pacing spike.

USES of PACEMAKER

usually used when a patient has a permanent or temporary slower-than-normal impulse formation, or a symptomatic AV or ventricular conduction disturbance. used to control some tachydysrhythmias that do not respond to medication. Biventricular (both ventricles) pacing, also called cardiac resynchronization therapy (CRT), may be used to treat advanced heart failure. used in an ICD (e.g., in patients with coronary artery disease and a reduced ejection fraction). can be permanent or temporary. Temporary pacemakers are used to support patients until they improve or receive a permanent pacemaker (e.g., after acute MI or during open heart surgery) Temporary pacemakers are used only in hospital settings.