word: pacemaker therapy self-instructional learning...
TRANSCRIPT
PROFESSIONAL DEVELOPMENT
SPECIALTY PEDIATRIC NURSING PRACTICE
ADVANCED COMPETENCIES
PACEMAKER THERAPY:
SELF-INSTRUCTIONAL LEARNING PACKAGE
(SILP)
March 2019, version 2.0
ContentsGetting Started....................................................................................................................................................3
A Quick Review....................................................................................................................................................4
Learning Activity #1.............................................................................................................................................4
Conduction: A Brief Review.................................................................................................................................5
Electrocardiography............................................................................................................................................5
The heart has two types of cells:.........................................................................................................................6
Electrocardiography............................................................................................................................................6
Pacemaker Therapy.............................................................................................................................................7
Pacemakers and the Pediatric Patient:............................................................................................................7
What is a pacemaker?.....................................................................................................................................7
Types of Cardiac Pacing:..................................................................................................................................8
Temporary Pacemakers.......................................................................................................................................9
Types of Temporary Pacing Methods:...........................................................................................................10
Equipment and Supplies....................................................................................................................................11
Learning Activity #2...........................................................................................................................................12
Learning Activity #3...........................................................................................................................................14
Medtronic Model 5392 Pacemaker...................................................................................................................15
Principles of Pacing............................................................................................................................................16
Pacemaker Identification Codes – Describing Pacemaker Function..................................................................18
Dual-Chamber Pacemakers...............................................................................................................................20
Single-Chamber Pacemakers.............................................................................................................................22
A Closer Look at the Pacemaker........................................................................................................................23
Pacemaker Settings...........................................................................................................................................23
Rate:..............................................................................................................................................................23
Output:..........................................................................................................................................................23
Sensitivity:.....................................................................................................................................................24
A-V Interval:...................................................................................................................................................26
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Cardiac monitoring using a Philips monitor is essential when caring for a child with a temporary pacemaker:....................................................................................................................................................26
Learning Activity #4...........................................................................................................................................27
Nursing Care of Children with Temporary Epicardial Pacer Wires.....................................................................27
Learning Activity #5...........................................................................................................................................28
Considerations...................................................................................................................................................28
Summary...........................................................................................................................................................29
Troubleshooting................................................................................................................................................32
Pacer Wire Removal – Considerations...............................................................................................................35
Family Resources...............................................................................................................................................36
Learning Activity #6...........................................................................................................................................37
Pacemaker Terminology....................................................................................................................................38
Answer Key........................................................................................................................................................41
References.........................................................................................................................................................42
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Getting StartedPrior to starting this learning module, take some time to review and complete the learning activities in the “Non-Invasive Hemodynamic Monitoring” Self-Instructional Learning Package (SILP) that is available on ePOPS. Nurses working in areas of the hospital that care for children with pacemakers need to be familiar with the normal anatomy and physiology of the cardiovascular system, including the principles of cardiac conduction.
Complete the ECG Clinical Skills validation tool with a Clinical Resource Nurse or Advanced Practice Partner and correctly identify the characteristics of Normal Sinus Rhythm (NSR).
Some of the children you will care for will require cardiac pacing. It is essential that nurses understand the basics of pacemaker function and be able to identify and safely manage pacemaker problems should they occur.
The goal of this learning package is to increase the nurse’s confidence, knowledge and skill when caring for patients requiring cardiac pacing. On completion of this SILP you will have the opportunity to:
Define common terminology associated with pacemaker therapy. Identify the components of a pacemaker system. Describe basic functions of pacemakers used. Identify possible complications of pacing. Describe the nursing care required by a patient receiving pacemaker therapy. Describe ways to troubleshoot problems that can occur with temporary epicardial pacing.
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A Quick ReviewThere are three important components of the cardiovascular system.
Learning Activity #1Take a few moments to refresh on the anatomy of the heart. Label the diagram below.
Figure 1: Anatomy of the Heart (Rogers & Scott, 2011)
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The continuous network of vessels through which the heart mechanically pumps the bloodCirculatory
The electrical wiring system that stimulates the heart to pumpConduction
The arteries and veins that provide oxygenated blood to meet the metabolic needs of the heart itselfCoronary
Conduction: A Brief Review
(Coviello, 2016)
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The heart is able to beat on its own because it has its own internal pacemaker called the sinoatrial (SA) node, which stimulates the heart to beat. The SA node is a specialized bundle of pacemaker cells
located at the top of the right atrium.
Heart cells contract (shorten) when they become electrically stimulated. This is called depolarization. The heart beat is initiated when the SA node cells depolarize. The ability to depolarize spontaneously, without electrical stimulation is called automaticity. This is a property of pacemaker cells. Normally, the SA node has the fastest rate of automaticity. The firing of the SA node stimulates both the left and right atria to contract.
The impulse then travels through a network of tracts to the AV node. The AV node is at the junction between the atria and ventricles.
Once the wavefront of depolarization arrives at the AV node it is delayed for a short time (0.04 sec) to allow the ventricles to fill. This is seen as the PR interval on the ECG.
Then the impulse travels down from the AV node to specialized conduction tissue called the Bundle of His, after which the conduction pathway divides into two branches: the left and right bundle branch.
Purkinje fibers extend from the bundle branches into the endocardium and deep into the myocardial tissue.
Conduction of the electrical stimulus to the myocardial cells causes the ventricles to contract.
The lower parts of the conduction system ARE NOT accustomed to initiating impulses. This can lead to unstable rhythms, some of which can be life threatening.
ElectrocardiographyThe heart has two types of cells:
Electrocardiography
The ECG Complex represents the electrical activity in one cardiac cycle, meaning that it represents the conduction of electrical impulses from the atria to the ventricles. The ECG complex is broken down into parts or waveforms which are labeled using the letters P through U.Each wave form represents specific electrical activity with in the heart.
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Myocardial Cells
Contractile units that allow the cell to contract when the cell is stimulated electrically
Pacemaker Cells
Specialized cells that can spontaneously generate and conduct electrical impulses
ALL HEARTBEATS PRODUCE AN ECG WAVE AND ALL ECG’S HAVE THE SAME BASIC ELEMENTS:
A set of P-QRS-T waves
Does this diagram look familiar? If you don’t have this on your lanyard, ask your Clinical Nurse Educator for one!
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Pacemaker Therapy
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Pacemakers and the Pediatric Patient:
Some children may require temporary epicardial pacing post cardiac surgery to temporarily increase the heart rate in the immediate postoperative period as a means of enhancing cardiac output until the heart is functioning normally again. Patients who have undergone surgical repair of congenital heart defects may develop conduction disturbances due to injury or edema of the sinoatrial or atrioventricular node.Some children may require permanent pacemakers for congenital or acquired heart block or asystole; others may need augmentation of their cardiac output or suppression of arrhythmias with the aid of a pacemaker.
As a nurse, you may have a patient that requires a pacemaker. Nurses practicing on 6 West, ACU, PICU and in the OR, maybe responsible for monitoring patients to ensure the effectiveness of pacemaker therapy. Nurses need to be familiar with pacemakers, and have a basic understanding their function, possible complications and troubleshooting.
What is a pacemaker?
A pacemaker is an artificial device that electrically stimulates the myocardium to depolarize, which begins a contraction. This device may be temporary or permanent. A pacemaker system consists of a pulse generator, pacing leads, and the electrode tip. The pulse generator houses a battery and electronic circuitry to sense (or see) and analyze the patient’s intrinsic rhythm and the timing circuitry for pacing stimulus output (Coviello, 2016).
The circuitry works like a computer, converting energy from the battery into electrical pulses. A pacing lead is an insulated wire used to carry an electrical impulse from the pacemaker to the heart. It also carries information about the heart’s electrical activity back to the pacemaker. The exposed portion of the pacing lead is called an electrode and is placed in direct contact with the heart.
An electrical stimulus from the pulse generator moves through the wires/pacing leads to the electrode tips. The leads for a pacemaker designed to stimulate a single heart chamber are placed in either the atrium or the ventricle. For dual-chamber, or AV pacing, the leads are placed in both chambers (Coviello, 2016).
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Types of Cardiac Pacing:
Pacemakers can be permanent or temporary.
Permanent pacemakers consist of leads that are anchored in or on the heart and a generator that is implanted in the body. Permanent pacemakers are usually required for life. The pacemaker’s circuitry is housed in a hermetically sealed case made of titanium that is airtight and impermeable to fluid.
The lead is placed transvenously for older children or surgically placed in the epicardium for infants and toddlers. Once the lead is in place, the pulse generator is implanted into the subcutaneous tissue of the abdomen of infants or the anterior chest in older children. The lead is then connected to the pulse generator.
Lithium batteries are almost exclusively used in modern pacemakers. Battery life depends on the following:
How much energy is required for capture. The percentage of time the device paces.
When the battery gets low, the entire pacemaker is replaced because the battery is sealed inside the pacemaker.
Temporary Pacemakers
The pulse generator of a temporary pacemaker is located externally.
Temporary cardiac pacing may be required in many situations in pediatric critical care. The purpose of a pacemaker is to deliver energy to the myocardium to stimulate depolarization when the patient’s intrinsic conduction is dysfunctional. It is most commonly initiated when one of the following conditions exists:
Advanced second or third degree block caused by certain drugs, or myocarditis.
Transient heart block associated with congenital heart surgery (usually a second or third degree block).
Tachyarrhythmia’s in which overdrive pacing may assist in reducing the heart rate or overdrive suppression of arrhythmia.
Symptomatic bradycardia in which pacemaker therapy may assist in improving the cardiac output.
(BC Children’s Hospital Pediatric Intensive Care Unit [BCCH PICU], 2007)
Types of Temporary Pacemaker Therapy
There are 4 types of temporary cardiac pacing that may be used. Temporary pacing is initiated in the critical care areas such as the OR or PICU.
Epicardial pacing is the only type of temporary pacing admitted onto 6 West.
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Types of Temporary Pacing Methods: Transcutaneous Two adhesive pads are placed on the chest wall for emergency ventricular
pacing. High energy is required due to the electrical resistance generated by the
tissue layers between the skin and the heart. Extremely painful to the child, so not usually done in a non-arrest situation. Once the child stabilized alternate pacing methods are considered. The Crash Cart Defibrillator is an example of this type.
Transvenous A pacing lead is placed via a major vein into the right atria or ventricle. The lead inserted transvenously is in contact with the endocardium of the
heart and is also referred to as endocardial pacing. Risks associated with this procedure include: pneumothorax, heart
perforation, air emboli, hemorrhage, infection and arrhythmias.Esophageal A lead is passed up the nose and fed down into the esophagus until it is
behind the left atrium. The wires are connected to a pacemaker and the current increased until
cardiac capture is obtained. Can only pace the atrium. This method is very uncomfortable as the voltage used is very high. May damage esophageal tissue if used for a continued for a prolonged
period of time.
Epicardial Most frequently used. Pacing wires are sutured directly to the epicardial surface of the right
atrium and ventricle during surgery. These chambers are selected because of their anterior anatomic position
when the chest is open. The epicardial wires are pulled through the chest wall before the
mediastinum is closed at the end of the surgical repair. Each set of epicardial wires splits into two distinct wires to attach to the
pacemaker. The wires in each set will function as either the “lead” or the “ground”. The designation of the wires is arbitrary so either wire can be the “lead” or the “ground”.
By international convention, the wires located to the right of the child’s sternum are atrial wires; those located to the left of the child’s sternum, are ventricular wires.
Removal of these wires is performed by a Nurse Practitioner or Physician.
(BCCH PICU, 2007; Stollery, 2011)
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Equipment and Supplies
For the majority of patients having cardiac surgery, epicardial pacing is only needed temporarily to increase heart rate in the immediate postoperative period. Patients who have undergone surgical repair of congenital heart defects may develop conduction disturbances due to injury or edema of the sinoatrial or atrioventricular node.
The surgeon attaches temporary epicardial wires during the operative course to ensure that should pacing be required in the recovery period, it is immediately available. The wires are brought through the chest wall. There are connector pins on the distal end that can be inserted into cable connectors and attached to the pacemaker if needed.
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Learning Activity #2The pacemakers used at BCCH come from the Medtronic medical device company. Medtronic clinical experts are available to provide onsite support for physicians, nurses, ECG technicians, and patients. The Medtronic rep also facilitates staff education by presenting at 6 West Advanced Cardiac education days and periodically providing in-services. There are many tools and online resources available on the Medtronic website.
Access the Medtronic website https://www.medtronic.com/ca-en/index.html and visit the education and training resources at “Medtronic Academy”. Register (free) to access the interactive courses, videos and presentations. Check out the sample learning plans and consider your own goals to guide your learning.
Write your learning goals below:
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The next 2 slides are from Medtronic and were used in a PowerPoint presentation used at the Advanced Cardiac Ed Days and can be found on the 6th floor team site under “Cardiac Resources”..If you would like the entire PowerPoint, you may print it for your own reference.
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Learning Activity #3
Access your area Teamsite and review the resources available on Pacemakers on the Cardiac Sciences subsite.
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Medtronic Model 5392 Pacemaker
This houses the controls and energy source for pacing. It is powered by 2 AA batteries and contains the internal
software to both sense the patient’s native rhythm and to provide the electrical stimulus (output) to depolarize (capture) the myocardium.
It can be used for single chamber pacing or dual-chambered pacing.
Rate is determined by the rate dial. The AV interval on dual-chambered controls the amount
of time between atrial and ventricular stimulation (electronic PR interval).
The energy delivered to myocardium is determined by setting the output.
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Principles of Pacing
Temporary pulse generators have 2 main functions: To sense or “see” the heart’s intrinsic rate. To pace - deliver an electrical energy to the epicardium to stimulate depolarization of cardiac
cells when necessary. Depolarization of the myocardial cells should result in contraction of the heart muscle.
Sensing refers to the ability of the pacemaker device to detect intrinsic myocardial electrical activity. Sensing occurs when the pulse generator is in the synchronous or demand mode. The pacemaker either is inhibited from delivering a stimulus or initiates an electrical impulse.
Pacing occurs when the temporary pulse generator is activated, and the requisite level of energy travels from the pulse generator through the temporary wires to myocardium. This is known as pacemaker firing and is represented as a line or spike on the electrocardiogram reading.
Capture refers to the successful stimulation of the myocardium by the pacemaker, resulting in depolarization. It is evidenced on the ECG by a pacemaker spike, followed by either an atrial or a ventricular complex, depending on the chamber being paced.
(BCCH PICU, 2007)
On an ECG you should see a spike whenever the pacemaker sends an electric impulse to the heart muscle. That impulse appears as a vertical line or spike.
(Coviello, 2016)
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Modes of Temporary Pacing
The mode of a pacemaker indicates its functions. There are three modes of cardiac pacing.
Fixed-Rate (Asynchronous) Pacemakers
Impulses are continuously generated at the rate set by the pulse generator regardless of the underlying electrical activity of the heart.
Does not sense the patient’s own cardiac rhythm.
Demand(Synchronous, Noncompetitive) Pacemakers
The pacemaker is able to sense and respond to the patient’s intrinsic rhythm.
This method of pacing overcomes the danger of the pacemaker firing during vulnerable periods of the cardiac cycle.
A demand pacemaker discharges only when the patient’s heart rate drops below the pacemakers preset (base) rate.
For example, if the demand pacemaker was preset at a rate of 70 impulses per minute, it would sense the patient's heart rate and allow electrical impulses to flow from the pacemaker through the pacing lead to stimulate the heart only when the rate fell below 70 beats/min.
AV Sequential (Dual Chamber)
The pacemaker senses the patient’s own atrial and ventricular heart rates. It will then pace the atrium if the atrial rate drops below the pacemaker’s preset rate and pace the ventricle after a programmed delay.
This mode mimics normal cardiac physiology.
(BCCH PICU, 2007)
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Pacemaker identification codes are used to assist in identifying a pacemaker's preprogrammed pacing, sensing, and response functions. The first letter of the code identifies the heart chamber/s paced (stimulated).
O (none of the chambers are paced) A (atrium paced) V (ventricle paced) D (dual - both atrium and ventricle paced)
The second letter signifies the heart chamber in which the pacemaker senses intrinsic activity. O (none of the chambers are sensed) A (atrium sensed) V (ventricle sensed) D (dual - both atrium and ventricle sensed)
The third letter indicates how the pacemaker will respond when it senses patient-initiated electrical activity: O (no sensing) T (a pacemaker stimulus is triggered in response to a sensed event) I (sensing of intrinsic impulses inhibits the pacemaker from producing a stimulus) D (dual - a combination of triggered pacing and inhibition)
Commonly encountered pacing modes are DDD, VVI, DVI, and DDDR.The fourth letter identifies whether the pacemaker can regulate the heart rate on its own, independent of the child’s own heart rate. It is most often used in permanent pacing and identifies the availability of rate responsiveness. A pacemaker's rate responsiveness may also be referred to as rate modulation or rate adaptation.
R (rate adaptive) O (not rate adaptive)
The fifth letter indicates the presence of one or more active antitachycardia functions and indicates how the pacemaker will respond to tachydysrhythmias:
O (no antitachycardia functions) P (capable of antitachycardia pacing) S (capable of delivering synchronized and unsynchronized countershocks) D (the device is capable of both of the above)
(Aehlert, 2006)
Pacemaker Identification Codes – Describing Pacemaker Function
An international code was developed by the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology (BPEG) to identify pacing modes. This code is known as the NBG code.
Although the code consists of five letters, only the first three are applicable to temporary pacemaker function.
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To trigger – initiate electrical stimulus.To inhibit – hold back electrical stimulus.
DDD VVI AAIA common mode of pacing is DDD. This mode paces and senses both atrium and ventricle. This mode also provides triggered and inhibited activity in response to sensed native electrical activity. If the sinus rate is sufficient and heart block is present, the generator will sense the P wave, wait for the preset AV interval and then begin looking for a native R wave. If the AV conduction does not occur and there is no native R wave, the generator will pace the ventricle.
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The 3 most common modes seen on 6 West are:
The 2 other modes that may be seen are:
AAI: Atria being paced, atrial sensing, inhibits when intrinsic atrial rate overrides set pacer rate. VVI: Ventricles being paced, ventricular sensing, inhibits when intrinsic ventricular rate overrides set pacer rate (V-demand).
**Approximately 80% of the children cared for on 6 West will be set in DDD mode.
Dual-Chamber Pacemakers
A pacemaker that paces both the atrium and ventricle has a two-lead system placed in the heart—one lead is placed in the right atrium, the other in the right ventricle. This type of pacemaker is called a dual-chamber pacemaker.
The AV sequential pacemaker stimulates the right atrium and right ventricle sequentially (stimulating first the atrium, then the ventricle), mimicking normal cardiac physiology and preserving the atrial contribution to ventricular filling (atrial kick).
The 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). 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 delay in conduction through the AV node (the PR interval). The “artificial” or “electronic” PR interval is referred to as an AV interval. If spontaneous ventricular depolarization does not occur within a preset interval, the pacemaker fires and stimulates ventricular depolarization at a preset rate.
The presence of a dual-chamber pacemaker does not necessarily mean that the pacemaker is in DDD mode. Dual-chamber pacemakers can be programmed to many modes including, VVI mode depending on patient need. (Coviello, 2016)
Benefits of DDD mode include: Versatility Programmability Ability to change modes automatically Ability to mimic the normal physiologic cardiac cycle, maintaining AV synchrony Ability to sense and pace the atria and ventricles at the same time according to the intrinsic
and maximal rate limit
(Coviello, 2016)
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Single-Chamber Pacemakers
A pacemaker that paces a single heart chamber (either the atrium or ventricle) has one lead placed on the heart.
Atrial pacing is achieved by placing the pacing electrode in/on the right atrium.
Stimulation of the atria produces a pacemaker spike on the ECG, followed by a P wave. Atrial pacing may be used when the SA node is diseased or damaged, but conduction through
the AV junction and ventricles is normal.
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This type of pacemaker is ineffective if an AV block develops because it cannot pace the ventricles.
Ventricular pacing is accomplished by placing the pacing electrode in/on the right ventricle.
Stimulation of the ventricles produces a pacemaker spike on the ECG followed by a wide QRS, resembling a ventricular ectopic beat.
The QRS complex is wide because a paced impulse does not follow the normal conduction pathway in the heart.
A Closer Look at the Temporary Pacemaker
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Pacemaker Settings
Rate: Low rate is the minimum number of electrical impulses, that need to be sensed or generated
per minute. The rate is the programmed rate even if the child’s heart rate is faster. The child’s lowest heart rate should be the programmed rate. If a child’s heart rate (atrial and ventricular) is above the pacing programmed rate, the
pacemaker will sense the intrinsic activity and no electrical stimulation will be given. No pacing spikes should appear on the ECG monitor.
The child’s highest heart rate, therefore, will vary according to the intrinsic rhythm. Every time the pacemaker fires, a pacing spike (a vertical line) should be evident on the ECG
monitor prior to the respective waveform.
Output: An expression of electrical power measured in milliamps (mA). Can be atrial and/or ventricular depending upon the selected pacing mode. The larger the number of mA used, the greater the electrical current delivered to the heart. The greater the required output, the higher the risk of diaphragmatic pacing. The “capture threshold” is the voltage required to generate depolarization of cardiac tissue.
The capture threshold is the output (in mA) at which the pacemaker impulse captures the myocardium and a P or QRS wave appears on the ECG monitor.
Once the “capture threshold” is determined, the output is set 2-3 times higher to provide a safety margin.
It is not uncommon for a child to require pacemaker setting adjustments either daily or every second day. Fibrous tissue build-up between the pacing wire and the surface of the heart will continue to accumulate as pacing continues. The fibrous tissue impedes the electrical stimuli, thus loss of capture can occur.
Increased output (mA) may be required in children post cardiovascular surgery due to tissue or electrolyte abnormalities or medications used.
If the child requires 20-25 mA to consistently pace the heart, epicardial pacing may soon fail. Depending upon the child’s intrinsic rhythm, permanent or temporary transvenous pacing may be considered.
Sensitivity: The pacemaker’s ability to detect (sense) intrinsic cardiac electrical activity measured in
millivolts (mV).
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The pacemaker’s sensitivity is programmed to sense and respond to intrinsic cardiac events. This prevents competition between intrinsic cardiac depolarization and paced depolarization.
Sensing can be atrial, ventricular, or both, depending upon the mode used. The pacemaker senses an intracardiac signal of specific programmed amplitude (strength),
according to the programmed SENSITIVITY. Usually when intrinsic cardiac activity is sensed, the pacing impulse is inhibited and the
pacemaker resets so that pacing occurs only when the heart fails to maintain an adequate heart rate.
The smaller the mV setting, the more sensitive the pacemaker is to intrinsic cardiac activity. The larger the mV setting, the less sensitive the pacemaker is to intrinsic cardiac activity.
Sensitivity Threshold: The minimum P or R wave amplitude needed for the pacemaker generator to detect or "see" is known as the sensitivity threshold.
If the intrinsic electrical signal is lower than the programmed amplitude, the pacemaker will pace the chamber(s) as per the pacemaker settings. For example, if the sensitivity is set at 10 mV, the intrinsic electrical impulse must be at least 10 mV in strength before the pacemaker will detect it.
If the pacemaker sensitivity is set at 1 mV, the intrinsic cardiac electrical impulse only needs to be 1 mV in strength to be sensed.
“The parameter we program to determine what size signal the pacemaker will sense is the SENSITIVITY. Increasing the value means the pacemaker is LESS ABLE to sense smaller signals, or is less sensitive. Decreasing the number of the sensitivity setting will allow the pacemaker to “see” more of the intrinsic signal (Medtronic PPP 2016)”.
The simple analogy to sensing is a fence. In this example the sensitivity number is set to 5.0 mV which is higher than the signal size = signal not sensed.
If we programmed the pacemaker is so it is unable to see any intrinsic activity we would call it undersensing. Undersensing means the pacemaker is unable to “see” intrinsic cardiac events.
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In this example the sensitivity value is much less. By programming a lower value it’s made the pacemaker MORE sensitive. The pacemaker can sense not only the QRS, but also the T-wave. This is an example of oversensing.
A-V Interval: The time interval between atrial activity (sensed or paced) and ventricular electrical
impulses, in milliseconds (mS). The AV interval ensures synchronization of atrial and ventricular depolarizations. Once an atrial impulse is sensed or delivered, the pacemaker will wait for the programmed
amount of time (A-V interval). If no QRS is sensed, the pacemaker will send an electrical impulse to the ventricle. If a QRS is sensed with the allotted time interval, the pacemaker will not deliver an electrical impulse, but will wait for the next beat.
Cardiac monitoring using a Philips monitor is essential when caring for a child with a temporary pacemaker : Printing or recording a rhythm strip is essential to evaluate the effectiveness of cardiac pacing.
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When monitoring the rhythm in a child that is paced: Ensure that the “PACED” function is turned on. If the pacemaker is sensing the child’s intrinsic rhythm, no pacing spikes should be seen on the
monitor. If the pacemaker is actively pacing the child, there should be a pacing spike prior to the
respective waveforms. If the pacing function is not turned on, the pacing spikes will be integrated into the rhythm.
Pacing spikes differ from ECG waveforms in that they have no area under the curve. Normally, they are perfectly straight vertical lines.
If the atria are paced, the pacing spike should appear immediately preceding the P wave. If the ventricles are paced, the pacing spike should appear immediately preceding the QRS
waveform. If both the atria and ventricles are paced, there should be a pacing spike prior to the P wave and
again prior to the QRS waveform.
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Assess and document the programmed settings on the pacemaker each shift.
Verify that the settings are the same as the Physician’s orders. If the ordered and programmed settings do not match, inform the Nurse Practitioner or Physician so that the order or the pacemaker settings may be changed as soon as possible.
Learning Activity #46 West has a designated backup pacemaker located in the team care station. Feel free to remove the pacemaker from the case and have it nearby to refer to and practice with as you watch the following videos on the Medtronic Website:Video 1: 5392 Dual Chamber Temporary External Pacemaker Overview of Physical Features & EnhancementsVideo 2: 5392 Temporary External Pacemaker Basic Functionality and User Interface OverviewVideo 3: 5392 Temporary External Pacemaker User Interface Overview Part IIVideo 4: 5392 Temporary External Pacemaker Single Chamber FunctionalityVideo 5: 5392 Temporary External Pacemaker Instructions for Preparation Before Use
https:// www.youtube.com/watch?v=AXr0CgKWr4g&list=PLMoNIeP0yzd9LDUnG6GOK-5OUy1zfwTDH
Nursing Care of Children with Temporary Epicardial Pacer Wires
The physician establishes and documents the pacing parameters, which must include the mode of pacing and the number of impulses (heart rate) per minute and settings for output and sensitivity.
Documentation must include rate and mode of pacing, output, sensitivity and A-V interval settings. The nurse must perform hourly site to source checks on the equipment ensuring that there is no
tension on the wires and all connections are tight and secure and that the pacemaker light indicators (Sense/Pace boxes) are flashing indicating atrial sensing or pacing and ventricular sensing or pacing.
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Learning Activity #5
There are 4 resources available on ePOPS to support your learning and to guide your practice. Access the “Monitoring Patients with a Temporary External Epicardial Pacemaker” policy and review it with your advance practice partner or NP.http://policyandorders.cw.bc.ca/resource-gallery/Documents/BC%20Children's%20Hospital/CC.09.05%20Monitoring%20Patients%20with%20a%20Temporary%20External%20Epicardial%20Pacemaker.pdf
Considerations
The Medtronic 5392 pacemaker has no audible alarm. A low battery indicator will flash in the left-hand corner of the LED screen. From the time the battery indicator begins to flash until the pacemaker stops, there is a 24-hour leeway. Upon noting a flashing battery, it is best practice to have the battery changed as soon as possible.
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Monitor the patient for systemic signs of infection, such as fever, chills, and malaise. Perform site care according to policy.
Arrhythmias can occur when the pacemaker is not sensing appropriately.
(BCCH PICU, 2007) Continuous ECG monitoring is required for all patients with temporary epicardial pacing.
It provides a tool for ongoing assessment of the pacemaker’s function and ensures rapid response if pacemaker failure occurs.
Setting cardiac monitor alarms just below and above the prescribed pacing heart rate so that failure to sense and/or capture is recognized immediately. The Philips cardiac monitoring system requires manually programming “pacemaker” mode.
Record/print an ECG rhythm strip at the beginning of each shift and with any changes in patient’s condition or pacemaker settings. Confirm that a palpable heart rate (mechanical cardiac function) correlates with heart rate on monitor.
Monitor vital signs, peripheral pulses, oxygenation, level of consciousness, skin temperature, color, PEWS and urine output every 4 hours and with any changes in settings.
Checking the security of all lead connections and the pacemaker at every assessment. This is especially important for ambulatory patients.
Assess pacing wire exit site for signs of infection or possible lead tension (pulling). Ensure the wires are fixed to the skin with tape or other securement device to prevent traction or displacement. Document any redness, edema, and drainage.
Safety precautions are vital with epicardial pacing since the wires provide a direct route to the myocardium. A microshock, an electrical current that passes through the body to the myocardium, can cause an atrial or ventricular dysrhythmia. Sources of microshock are stray electrical current, electricity, and ungrounded equipment. To prevent a microshock, wear gloves when handling the wires.
When epicardial pacing wires are not in use, they must be insulated. Temporary Epicardial Pacemaker Policy
Labeling the pulse generator with the date and time of each battery change. Verify that the battery has been changed within the previous 7 days.
Ensuring spare AA batteries and the backup pacemaker is available at the 6 West team care station all times.
Summary
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Troubleshooting Despite careful monitoring and fine-tuned settings, problems may occur. For example, the pacemaker may not deliver a pacing stimulus, the pacing stimulus may not cause a depolarization, the pacemaker may not sense the patient’s intrinsic heart rate, or the generator may sense irrelevant electrical signals that it interprets as the patient’s intrinsic rate.
Undersensing or failure to sense occurs when the pacemaker generator fails to see intrinsic beats. Causes include: • Sensitivity set too high• Inappropriate mode selection • Loose cable connections • Lead displacement • Generator failure • Myocardial factors• Electrode issues
Measures to correct undersensing include: • Lowering the sensitivity. • Checking all connections. • Changing the pacemaker generator
Failure to Sense
Oversensing occurs when the pacemaker generator senses events in addition to intrinsic patient QRS or ventricular depolarization. Pauses in the rhythm strip tracing show up as the generator senses adventitious signals. Causes include:• Electromagnetic interference (EMI) • Muscle or myopotentials • Improperly grounded equipment • T waves • Sensitivity set too low
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Measures to prevent oversensing include:• Identifying all sources of EMI and eliminating them. • Lowering the sensitivity of the pacemaker generator by increasing the sensitivity number.
Failure to pace results in the absence of pacing artifact. Causes include:• Loose cable connections • Oversensing • Electromagnetic interference • Battery depletion • Generator failure • Problems with the epicardial wires
If pacing spikes are absent on the ECG monitor, check all connections. If all are secure, try decreasing the sensitivity by dialing up to a higher number. Other nursing interventions include changing the battery or generator, eliminating any source of EMI, and changing the polarity of the epicardial wires.
Failure to Pace (no output) on a bradycardic rhythm
Loss of capture is classified as pacing artifact on the ECG tracing not followed by the P wave or QRS complex. Cause of loss of capture may be due to:• Loose cable connections • Increased pacing threshold • Displaced or defective pacing electrodes • Depleted battery • Output set too low • Metabolic or electrolyte disorder
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Measures to troubleshoot loss of capture include: • Checking all connections from the epicardial wires to the pacemaker generator. • Trying a change of polarity of the epicardial wires if all connections are secure. • Increasing the mA if the change in polarity doesn’t work.
Loss of Capture – no wave followed by pacemaker spike
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Nurses play a vital role in the care of patients undergoing temporary epicardial pacing as they assess pacemaker function, monitor for complications, and educate patients and family members. MRI Safety: TEMPORARY PACING WIRE/SYSTEMS ARE NOT COMPATIBLE WITH MRI SCANNERS. http://www.bcchildrens.ca/radiology%20site/Documents/BCCH%20MRI%20Patient%20Screening%20Form.pdf https://health.clevelandclinic.org/are-mri-scans-safe-if-you-have-a-pacemaker-or-implanted-device/
Pacer Wire Removal – Considerations
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Before discharge from 6West the NP or cardiothoracic surgeon will remove the epicardial pacing wires. This is done at the bedside. After removal, the patient must be monitored for signs and symptoms of arrhythmias, bleeding and cardiac tamponade. If blood or fluid collects in the pericardial sac, the build-up will compresses the heart and interfere with normal contraction and cardiac output.
Signs and symptoms of tamponade include: jugular venous distention muffled heart sounds hypotension tachycardia/ tachypnea diaphoresis cool extremities/decreased peripheral pulses decreased oxygen saturation pale and/or mottled extremities pulsus paradoxus
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Epicardial pacing wires are usually one of the last items to be removed from the child before discharge. These wires are left in place until the child is almost ready for discharge. Nurse practitioners or physicians remove the pacemaker wires.
To remove the wires the NP or physician will pull them out one at a time. Consider providing analgesics 30 minutes prior to the procedure and coordinating with the Child Life Specialist to assist with distraction and age appropriate coping techniques.
Bleeding may occur due to the possible removal of fibrous tissue that has formed between the heart and the wire.
It is uncommon to have a large amount of bleeding. The potential for excessive blood loss and cardiac tamponade exists, especially with a child that has had a prolonged recovery time, has had temporary pacing for an extended period of time, is nutritionally deficient, or is receiving anticoagulation therapy.
In preparation for pacing wire removal, the NP will review the patients’ blood work (platelet count and coagulation studies). If the child is receiving therapeutic heparin, Enoxaparin or Coumadin, they may consider holding the drug for several hours prior to and after removal.
Following removal of the pacing wires, the child requires continuous cardiorespiratory monitoring, also monitor vital signs (HR, RR and BP) every 15 minutes for one hour and observe the child for possible complications for at least 4 hours following removal. Encourage low key, calm activities immediately post removal.
Monitor for signs and symptoms of cardiac tamponade. Immediately notify the physician /NP when patient experiences: unexplained tachycardia, tachypnea, hypotension, decreased cardiac output with poor peripheral perfusion, decreased urinary output, change in level of consciousness, and muffled heart sounds.
Document on the Daily Flowsheet and record an ECG rhythm strip before wires are removed. Once wires are removed - repeat Q 30 minutes 30 minutes x2 then as needed if abnormalities observed.
An echocardiogram will be done post drain removal and prior to discharge.
Family resources
The online BCCH Family Resource Center has some helpful resources for families with Permanent (Implanted) pacemakers. Check out a few of the links. http://www.bcchildrens.ca/Resource-Centre-site/Documents/P-Q/BCCH1392_CareOfYourChildWithPacemaker_2013.pdf
http://www.bcchildrens.ca/Heart-Centre-Site/Documents/travel_checklist_sept%20_2012.pdf
About Kids Health and Children’s Hospital of Philadelphia (CHOP) also have some great resources for caregivers and families.
Learning Activity #6
Congratulation you have completed the Pacemaker SILP. Please access and review the Clinical Skills Validation tool on ePOPS with an Advanced Practice Partner. Complete the checklist, review your learning goals, and plan to have your skills validated at the bedside.
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Pacemaker Terminology
A wave: Atrial paced event; the atrial stimulus or the point in the intrinsic atrial depolarization (P wave) at which atrial sensing occurs; analogous to the P wave of intrinsic waveforms.
AA interval: Interval between two consecutive atrial stimuli, with or without an interceding ventricular event; analogous to the P-P interval of intrinsic waveforms.
Asynchronous pacemaker: (Fixed-rate) pacemaker that continuously discharges at a preset rate regardless of the patient's intrinsic activity. No sensing.
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Atrial pacing: Pacing system with a lead attached to the right atrium designed to correct abnormalities in the SA node (sick sinus syndrome).
Automatic interval: Period, expressed in milliseconds, between two consecutive paced events in the same cardiac chamber without an intervening sensed event (e.g., AA interval, VV interval); also known as the demand interval, basic interval, or pacing interval.
AV interval: In dual-chamber pacing, the length of time between an atrial sensed or atrial paced event and the delivery of a ventricular pacing stimulus; analogous to the PR interval of intrinsic waveforms; also called the artificial or electronic PR interval.
AV sequential pacemaker: Pacemaker that stimulates first the atrium, then the ventricle, mimicking normal cardiac physiology; a type of dual-chamber pacemaker.
Base rate: Rate at which the pulse generator paces when no intrinsic activity is detected; expressed in pulses per minute (ppm). Same as low rate.
Bipolar lead: Pacing lead with two electrical poles that are external from the pulse generator; * the negative pole is located at the extreme distal tip of the pacing lead; the positive pole is located several millimeters proximal to the negative electrode; the stimulating pulse is delivered through the negative electrode. (*Note, this only applies to permanent transvenous leads).
Capture: Ability of a pacing stimulus to successfully depolarize the cardiac chamber that is being paced; with one-to-one capture, each pacing stimulus results in depolarization of the appropriate chamber.
Demand (synchronous) pacemaker: Pacemaker that discharges only when the patient's heart rate drops below the preset rate for the pacemaker.
Dual-chamber pacemaker: Pacemaker that stimulates the atrium and ventricle; dual-chamber pacing is also called physiologic pacing.
Escape interval: Time measured between a sensed cardiac event and the next pacemaker output.
Fusion beat: In pacing, the ECG waveform that results when an intrinsic depolarization and a pacing stimulus occur simultaneously, and both contribute to depolarization of that cardiac chamber.
Hysteresis: Programmable feature in some demand pacemakers that allows programming of a longer escape interval between the intrinsic complex and the first paced event; the longer escape interval allows intrinsic beats an opportunity to inhibit the pacemaker.
Inhibition: Pacemaker response in which the output pulse is suppressed (inhibited) when an intrinsic event is sensed.
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Interval: Period, measured in milliseconds, between any two designated cardiac events; in pacing, intervals are more useful than rate because pacemaker timing is based on intervals.
Intrinsic: Inherent; naturally occurring.
Milliampere (mA): Unit of measure of electrical current needed to elicit depolarization of the myocardium.
Output: Electrical stimulus delivered by the pulse generator, usually defined in terms of pulse amplitude (volts) and pulse width (milliseconds).
Pacemaker: Artificial pulse generator that delivers an electrical current to the heart to stimulate depolarization.
Pacemaker spike: Vertical line on the ECG that indicates the pacemaker has discharged.
Pacemaker syndrome: Adverse clinical signs and symptoms that limit a patient's everyday functioning and occur in the setting of an electrically normal pacing system; common signs and symptoms include weakness, fatigue, dizziness, near or full syncope, cough, chest pain, hypotension, dyspnea, and congestive heart failure; pacemaker syndrome is most commonly associated with a loss of AV synchrony (e.g., VVI pacing) but may also occur because of an inappropriate AV interval or inappropriate rate modulation.
Pacing interval: Period, expressed in milliseconds, between two consecutive paced events in the same cardiac chamber without an intervening sensed event (e.g., AA interval, VV interval); also known as the demand interval, basic interval, or automatic interval.
Pacing system analyzer (PSA): External testing and measuring device capable of pacing the heart during pacemaker implantation; used to determine appropriate pulse generator settings for the individual patient (e.g., pacing threshold, lead impedance, pulse amplitude).
Parameter: Value that can be measured and sometimes changed, either indirectly or directly; in pacing, parameter refers to a value that influences the function of the pacemaker (e.g., sensitivity, amplitude, mode).
Pulse generator: Power source that houses the battery and controls for regulating a pacemaker.
Rate modulation: Ability of a pacemaker to increase the pacing rate in response to physical activity or metabolic demand; some type of physiologic sensor is used by the pacemaker to determine the need for an increased pacing rate; also called rate adaptation or rate response.
R wave: In pacing, R wave refers to the entire QRS complex denoting an intrinsic ventricular event.
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RV interval: Period from the intrinsic ventricular event and the ventricular-paced event that follows; the pacemaker's escape interval.
Sensing: Ability of a pacemaker to recognize and respond to intrinsic electrical activity; the pacemaker's response to sensed activity depends on its programmed mode and parameters.
Threshold: Minimum level of electrical current needed to consistently depolarize the myocardium.
Unipolar lead: Pacing lead with a single electrical pole at the distal tip of the pacing lead (negative pole) through which the stimulating pulse is delivered; in a permanent pacemaker with a unipolar lead, the positive pole is the pulse generator case.
V-A interval: In dual-chamber pacing, the interval between a sensed or ventricular-paced event and the next atrial-paced event.
V-V interval: Interval between two ventricular-paced events.
V wave: Ventricular-paced event; the ventricular stimulus or the point in the intrinsic ventricular depolarization (R wave) during which ventricular sensing occurs.
Ventricular pacing: Pacing system with a lead attached in the right ventricle.
(Coviello, 2006)
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Answer Key
Figure 1: Anatomy of the Heart
(Rogers & Scott, 2011)
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References
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American Association of Critical Care Nurses. (2007). Procedure Manual for Pediatric Acute and Critical Care. St. Louis: Elsevier.
BC Children’s Hospital Pediatric Intensive Care Unit. (2007). Pacemaker Therapy Learning Package. Vancouver, BC.
Bolton, J., & Mayer, J. (1992). Unusual complication of temporary pacing wires in children. Annals of Thoracic Surgery, 54(4), 769 - 770.
Boyle, J, Rost, M.K. (2000). Present state of cardiac pacing: A nursing perspective. Critical Care Nursing Quarterly, 23 (1), p. 1-19.
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Craig, J., Bloedel Smith, J., Fineman, L.D. (2001): Tissue perfusion. In Curley, M., Maloney-Harmon, P.A.: Critical care nursing of infants and children. Second edition. Philadelphia: Saunders.
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Medtronic (1998). Model 5388 Temporary pacemaker in-service participant handout.
Merva, J.A. (1992). Temporary pacemakers. RN, 55(5), 28-33.
Minninni, N. C. (2012). The beat goes on: a pacemaker primer. American Nurse Today, 7(3), 26–31.
Overbay, D., & Criddle, L. (2004). Mastering temporary invasive cardiac pacing. Critical Care Nurse, 24(3), 25 – 32.
Park, M.K. (2002). Pacemakers in children. In Pediatric cardiology for practitioners, 4th Ed. Boston, Massachusetts: Mosby
Pitfield, S. (2013) Pacemakers. [Powerpoint slides]. BC Children’s Hospital. Vancouver, BC.
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Reynolds, J., & Apple, S. (2001). A systemic approach to pacemaker assessment. AACN Clinical Issues: Advanced Practice in Acute and Critical Care. 12(1), 114 – 126.
Rogers, K. M. A., & Scott, W. N. (2011). Nurses! Test Yourself in Anatomy and Physiology. Berkshire, England: McGraw-Hill Education.
Stollery Children’s Hospital. (2011). Pediatric Pacing Learning Package. Edmonton, Canada.
Timothy, P. R., & Rodeman, B. J. (2004). Temporary pacemakers in critically ill patients. AACN Clinical Issues, 15(3), 305 – 325.
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