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single chamber temporary pacemakers

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  • Pacemakers provide electrical stimuli to cause cardiac contraction during periods when intrinsic cardiac electrical activity is inappropriately slow or absent.
  • Pacing systems consist of frau sucht mann hanau a pulse generator and flirten für männer wie spreche ich eine frau an pacing leads.
  • Pacemaker output generally stimulates the cavity of the right atrium and/or right ventricle (endocardial pacing). Alternatively, epicardial leads can be implanted surgically on to the heart's surface.
  • The battery most commonly used in wie flirten männer im internet permanent pacers has a lifespan of five to nine years.[]
  • The pulse generator is internal in permanent pacemakers (subcutaneously or submuscularly) and external in temporary pacing.
  • It can be set to a fixed-rate (asynchronous) or demand (synchronous) mode.
  • In the fixed-rate mode, there is a small risk of producing dangerous dysrhythmias if the impulse coincides with the vulnerable period of the T wave.
  • On-demand pacemakers detect spontaneous ventricular activity and the output of the pacemaker is either suppressed or discharged in order to make the impulse fall within the safe period of the QRS complex.

Unipolar pacemakers

  • Permanent leads are either unipolar (where a single contact is made with the heart) or bipolar.
  • Unipolar systems (ventricular) are used in cases where atrioventricular (AV) conduction is likely to return.
  • When there is normal AV conduction and a sinoatrial (SA) disorder then the pacing wire is situated in the right atrium.

Dual-chamber pacemakers

  • Have pacing electrodes in both the right atrium and the right ventricle.
  • They allow maintenance of the physiological relationship between atrial and ventricular contraction and also allow the paced heart to follow the increase in sinus rate that occurs during exercise.

Dual-site atrial pacing

  • Newer pacing systems have two atrial leads, one in the right atrial appendage and the other either in the coronary sinus or at the os of the coronary sinus.
  • The ventricular lead is in the right ventricle, either at the apex or at the outflow tract.
  • This system has been proposed as a promising treatment option for prevention of paroxysmal atrial fibrillation.[]

Biventricular pacemakers

  • Pacemaker leads are placed in the right atrium, right ventricle and left ventricle.
  • Useful in the management er sucht sie karlsruhe of patients with heart failure who have evidence of abnormal intraventricular conduction (most often evident as left bundle branch block (LBBB) on ECG) which causes deranged ventricular contraction or dyssynchrony.[]

Implantable cardioverter defibrillators (ICDs combined with internal defibrillator)

  • Designed to treat a cardiac tachyarrhythmia directly.
  • If a patient has a ventricular defibrillator and the device senses a ventricular rate that exceeds the programmed cut-off rate of the defibrillator, the device performs cardioversion/defibrillation.
  • Alternatively, the device, if so programmed, may attempt to pace rapidly for a number of pulses, usually around 10, to attempt pace-termination of a ventricular tachycardia.

The North American Society of Pacing and Electrophysiology and the British Pacing and Electrophysiology Group have developed a code to describe various pacing modes. It usually consists of three letters, but some systems use four or five:

  • Letter 1: chamber that is paced (A = atria, V = ventricles, D = dual-chamber).
  • Letter 2: chamber that is sensed (A = atria, V = ventricles, D = dual-chamber, 0 = none).
  • Letter 3: response to a sensed event (T = triggered, I = inhibited, D = dual - T and I, R = reverse).
  • Letter 4: rate-responsive features; an activity sensor (eg, an accelerometer in the pulse generator) in single or dual-chamber pacemakers detects bodily movement and increases the pacing rate according to a programmable algorithm (R = rate-responsive pacemaker).
  • Letter 5: anti-tachycardia facilities.

A pacemaker in VVI mode denotes that it paces and senses the ventricle and is inhibited by a sensed ventricular event. The DDD mode denotes that both chambers are capable of being sensed and paced.

  • Persisting symptomatic bradycardia.
  • Complete AV block (, asymptomatic, congenital), Mobitz type II AV block, persistent AV block post anterior myocardial infarction.
  • Pacemakers may have a role in the suppression of resistant tachyarrhythmias.
  • Prevention of.[, ]
  • Pacemakers have a role in the management of some patients with or.[]

The National Institute for Health and Care Excellence (NICE) recommends that dual-chamber pacemakers can be used to treat symptomatic bradycardia in people with, AV block, or both, but that there are a number of special circumstances where dual-chamber pacemakers should not be used for symptomatic bradycardia.[]


The patient must inform the Driver and Vehicle Licensing Agency (DVLA) that they have a pacemaker.

For an ordinary driving licence

  • The patient can start driving again after one week as long as:
    • There are no symptoms such as dizziness or fainting which may affect driving.
    • The patient attends regular check-ups in the pacemaker clinic.
    • The patient has not recently had a heart attack or heart surgery.

For a large goods vehicle (LGV) or passenger-carrying vehicle (PCV) licence

  • The patient cannot drive these vehicles for six weeks after the pacemaker is fitted.
  • The patient can apply for another licence when he/she no longer has any symptoms that would affect driving - eg, dizziness or fainting.
  • The current licence is replaced with a three-year licence and the patient will have to go to a pacemaker clinic regularly.


  • Any strenuous activity should be avoided for about three to four weeks after the pacemaker has been fitted. After that, the patient can continue or start most activities and sports.
  • For contact sports, care should be taken to avoid collisions that may damage the pacemaker, and a protective pad should be considered.

Hospitals and medical treatment

  • A doctor or technician should be informed that the patient has a pacemaker before any investigations or treatment.
  • Always show the pacemaker registration card to any doctor or dentist providing treatment.
  • Most pacemaker generators have an X-ray code that can be seen on a standard.
  • Some hospital equipment, including equipment used in surgery, may interfere with pacemakers. The pacemaker may need to be protected during any operation and reprogrammed afterwards.
  • Radiotherapy may damage the pacemaker's circuits. The degree of damage is unpredictable and may vary with different systems. But the risk is significant and builds up as the radiation dose increases. The pacemaker should be shielded as much as possible and moved if it lies directly in the radiation field.
  • MRI scans can be dangerous with a pacemaker and the patient should not have an MRI scan. If an MRI scan is absolutely necessary, the pacemaker output in some models can be reprogrammed.
  • Short-wave or microwave diathermy may bypass the pacemaker's noise protection and interfere with or permanently damage the pulse generator.
  • Transcutaneous electrical nerve stimulation (TENS) may sometimes briefly inhibit unipolar pacing, which then requires reprogramming of the pulse generator.

Outside interference

  • Most pacemakers are very resistant to outside interference and the pacemaker has special circuits to detect and remove unwanted electrical activity.
  • However, devices with risk include antitheft systems in shops and other business premises and metal detectors. They are unlikely to cause clinically significant symptoms in most patients but patients should not stay nearby for longer than is necessary.
  • Any hand-held metal detector should not be held near the pacemaker for any longer than is necessary.
  • Household devices such as shavers, hairdryers and microwave ovens are not a problem, as long as they are well maintained.
  • The following items can be used when they are kept 6 inches away from your pacemaker (it is usually the motor that may cause an electromagnetic field): Hand held hair dryers and older shavers with an electrical cord; pagers; sewing machines and servers (sewing machines that overcast edges to prevent fraying); electric toothbrush and the base charger of an ultrasonic toothbrush; large stereo speakers which often have large magnets. Do not lift large stereo speakers close to your pacemaker; when using an induction range for cooking keep your pacemaker 2 feet from the range.
  • Household tools such as drills, mowers and electric screwdrivers can be used normally.
  • A mobile phone or a cordless phone can be used safely, but the phone should be kept more than 6 inches away from the pacemaker. The ear on the opposite side to the pacemaker should always be used, and the phone should not be put in a pocket over the pacemaker.

Travelling and security systems

  • Airport screening systems and antitheft systems in shops and libraries may (rarely) cause problems and there is also a small chance that the pacemaker may trigger the alarms.
  • The pacemaker registration card should always be carried by the patient.
  • If a patient with a pacemaker has to go through a security gateway, they should go through quickly and not stand close to the gateway for too long.

At work

  • Some workplaces have strong electromagnetic fields which can interfere with the pacemaker - eg, arc welding.
  • Power-generating equipment, arc welding equipment and powerful magnets (as in medical devices, heavy equipment or motors) can inhibit pulse generators and there is a risk that the pacemaker may not work properly for patients who work closely with or near such equipment.

Further reading and references

  1. ; Cardiac pacing: the state of the art. Lancet. 2004 Nov 6-12364(9446):1701-19.

  2. ; American College of Cardiology/American Heart Association/North American Society for Pacing and Electrophysiology, 2002

  3. ; Dual-site right atrial pacing increases left atrial appendage flow in patients with sick sinus syndrome and paroxysmal atrial fibrillation. Pacing Clin Electrophysiol. 2007 Jan30(1):20-7.

  4. ; New pacing technologies for heart failure. BMJ. 2003 May 17326(7398):1073-7.

  5. ; NICE Technology Appraisal Guidance, February 2005

  6. ; Driver and Vehicle Licensing Agency

Disclaimer: Patient does not control or endorse the content of advertisements, which are supplied automatically by third parties.


  1. , RN, MS, CCRN, CCNS
  1. Devorah Overbay is a clinical transplant coordinator at Oregon Health & Science University in Portland, Ore. She is a former critical care and cardiovascular clinical nurse specialist.
  2. Laura Criddle is a doctoral student at Oregon Health and Science University.

Invasive electrical pacing is used to initiate myocardial contractions when intrinsic stimulation is insufficient, the native impulses are not being conducted, or the heart rate is too slow to maintain an adequate cardiac output. Several pacing options are available. Selection of a particular method depends on both the patient’s current condition and his or her projected future needs. Among patients with cardiac disease, noninvasive (transcutaneous), semi-invasive (esophageal), temporary invasive, and implanted (permanent) pacemakers are often indicated. In this article, however, we focus on those invasive but temporary pacemaker systems that critical care nurses often find confusing.

Temporary invasive pacing of the myocardium is used for a variety of emergent and elective conditions (Table 1). Pacing electrodes are routinely inserted during certain cardiac surgical procedures such as bypass grafting and valve repair or replacement. Another common indication for insertion of a temporary pacemaker is recent myocardial infarction. Although treatment with β-blocking agents is considered an important intervention after recent myocardial infarction, the agents slow the heart rate markedly. In addition, serious bradydysrhythmias often occur in patients with recent myocardial infarction even without drug therapy. These low heart rates interfere with successful recovery. Temporary pacing after myocardial infarction can be a lifesaving intervention, allowing patients to enjoy the benefits of β-blocker therapy while simultaneously maintaining an adequate heart rate and cardiac output.

View this table:
Table 1

Indications for temporary invasive cardiac pacing

Although the generators used with temporary pacemakers can be intimidating, familiarity with this equipment is essential for critical care nurses. In the following material, we review relevant cardiac anatomy and physiology, discuss various pacemaker components, and describe the nursing care of patients being paced with trans-venous or epicardial electrodes.

Cardiac Anatomy and Physiology

Microscopically, myocardial tissue is differentiated by the functions of its various cell types. Working myocardial cells contract, providing pumping forces; clusters of specialized pacemaker cells initiate electrical impulses; and the Purkinje fibers provide rapid conduction of these impulses. The sinoatrial node, located high in the right atrium, is the cluster of cells that initiates normal cardiac stimulation and serves as the primary pacemaker. These signals then travel across the atrium to the atrioventricular node, located close to the septal leaflet of the tricuspid valve. Conducting fibers from the atrioventricular node converge in the bundle of His, allowing rapid transmission of impulses to the Purkinje fibers of the ventricles (Figure 1). The result of this highly coordinated impulse propagation is a cardiac contraction that efficiently pumps blood throughout the entire circulatory system.

Figure 1
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Figure 1

Cardiac conduction system.

Many intrinsic and extrinsic factors influence the genesis and the propagation of cardiac impulses. Dysrhythmias may arise from abnormal initiation or conduction of impulses or from both. Bradydysrhythmias can result from electrolyte imbalances, the toxic effects of drugs, inherent abnormalities in the conduction system, ischemia, or myocardial damage. By sustaining a rate sufficient to allow filling and emptying of the heart’s chambers, artificial mechanical pacemakers can be a lifesaving adjunct for maintaining an adequate cardiac output.

Components of Pacing

The mechanics of pacing involves several fundamental components. The first of these is the battery-powered generator that initiates electrical stimulation. Three basic types of pulse generators are available:

  1. single-chamber atrial pacers,

  2. single-chamber ventricular pacers, and

  3. atrioventricular sequential pacers, which pace both atrial and ventricular chambers.

Single-chamber atrial pacers are adequate for enhancing heart rate in patients with an intact cardiac conduction system. Ventricular pacers are designed for patients with normal contractility who require an increase in heart rate. Atrioventricular sequential pacers provide synchronization between the atria and the ventricles for optimal cardiac output.

The pacing generator is connected to 1 to 4 pacing wires and may or may not require a connecting cable between the wires and the generator. The last element of pacing is the patient’s own cardiac tissue. Failure to pace may be due to a malfunction or disruption of mechanical components. Failure may also be due to poor myocardial function associated with electrolyte disturbances, myocardial scarring, or any factors that affect impulse conduction or cardiac contractility.

Pacemaker Concepts

The four basic concepts of pacemaker functioning are connection, output, capture, and sensitivity.


The connection between the pacemaker generator and the heart is made through either unipolar or bipolar electrode wires. In a unipolar system, only the negative electrode is in direct contact with the heart. In a bipolar system, both negative and positive electrodes lie within the heart. Pacemakers can be either unipolar or bipolar. Distinguishing between the negative and positive electrodes is important so that the wires are connected appropriately to the pulse generator.

The 2 types of invasive temporary pacing are epicardial and transvenous. The transvenous category also includes devices that combine a specialized pulmonary artery catheter with a pacemaker. Transvenous pacing involves a pulse generator, which is externally connected to 2 electrode wires, threaded through a large vein (generally the subclavian or internal jugular) into either the right atrium or the right ventricle. These wires directly contact the endocardium within the heart (Figure 2).

Figure 2
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Figure 2

Temporary transvenous pacemaker.

Pulmonary artery catheters are the newest form of invasive temporary pacing. In specialized pulmonary artery catheters, dedicated atrial and ventricular ports provide sites for the introduction of electrode wires while still allowing routine thermodilution hemodynamic monitoring. Unfortunately, inflating the balloon to measure pulmonary artery wedge pressure may cause the electrodes to migrate out of their pacing position. Consequently, simultaneous pacing and determinations of wedge pressures are infrequently done.

The second method of temporary invasive pacing involves directly stimulating the epicardium (Figure 3). This type of pacing is initiated after cardiac surgery. Postoperatively, electrodes are lightly sutured to the epicardium before the thorax is closed. These pacing wires are pulled through the skin and secured to the external chest wall, ready for attachment to a temporary pacing generator as needed. A patient may have a single set or a double set of electrodes, but each set of electrodes includes 2 wires that protrude from a stab incision in the chest wall. When dual-wire sets are used, one set or pair paces the ventricles and the other is attached to the atria.

Figure 3
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Figure 3

Temporary epicardial pacemaker.

In each pair of wires, one lead is positive and the other (commonly the shorter of the 2 wires) is negative; however, practice varies between institutions. Ventricular pacing wires exit through the left side of the sternum; atrial pairs are placed on the right side. Having identifying labels on the wires is helpful. If no labels are present, ascertaining which wire is which (and marking the wires accordingly) can save precious time later in emergency situations.

Distinguishing ventricular wires from atrial wires, and positive electrodes from negative electrodes, is considerably easier in patients with transvenous or pulmonary artery catheter pacemakers. Pacing wires are threaded directly into the chambers of the right atrium and right ventricle by using the appropriate prelabeled ports.

On the top of the generator of each temporary atrioventricular sequential pacemaker are connectors labeled Atrial +/−, and Ventricular +/− (Figure 4). Single-chamber pacemakers have only 2 connector ports, positive and negative; the wires must be connected and secured to the correct port.

Figure 4
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Figure 4

Pulse generator for a dual-chamber pacemaker.


Once the wires from the patient are connected to the generator, the amount of electrical output must be selected. The sole function of the generator is to supply sufficient energy to the heart muscle to stimulate a contraction. Setting the output has 3 components: rate, amount, and chamber. The rate determines the number of stimulations to be delivered per minute. The amount controls the level of energy provided, and the chamber defines the location in the heart to which the energy is delivered.

Sometimes, the most obvious step in setting up a pacemaker is also the step most forgotten: ensuring that a fresh battery is in the generator. Most institutions have a policy that requires checking a battery’s energy level, or replacing the battery, before attaching the generator for each new patient. Table 2 is a quick guide to pacemaker setup.

View this table:
Table 2

Quick guide to pacemaker setup

Each patient’s physician is responsible for providing initial direction regarding rate, output amount, and chambers to be paced. To facilitate this step, some institutions have developed preprinted temporary pacemaker orders. Other critical care units have temporary pacing policies in place to provide nurses with guidelines for initial settings.


The original rate setting depends on both the patient’s condition and the reason for pacing. Rates for a surgical patient can start as high as 90 to 110 beats/min. In medical patients, therapy is generally started at 70 to 90 beats/min. In patients who have had cardiac arrest, the initial rate is 80 beats/min. Pacing rates for overdrive suppression of tachydysrhythmias may greatly exceed these values. The heart rate on a patient’s rhythm strip should never be lower than the patient’s set pacemaker rate.


The output amount is the level of energy delivered by the pulse generator to the heart to initiate depolarization. Output is measured in milliamperes. The usual starting point is 10 mA in nonurgent situations. Output is then slowly increased until capture is obtained and the “pacing threshold” is defined. This level is not constant; it fluctuates over time as an endothelial sheath forms around the tips of the electrodes. Therefore, to prevent loss of capture, the output is set 1½ to 3 times higher than the identified pacing threshold. In emergent circumstances, starting with a high output (15–20 mA) is recommended. Threshold testing is performed to fine-tune the settings.


The atrial chamber, the ventricular chamber, or both chambers of the heart can be paced. Pulse generators for dual-chamber pacemakers have separate atrial and ventricular output controls. If both the atrium and the ventricle are paced, a separate output setting is required for each chamber. The settings for the 2 chambers may be different or identical. The chamber to be paced is selected by programming the generator.


Electrical capture, the ability of the electrical impulse to initiate a cardiac response, is detected by examining an electrocardiogram. Capture is both an electrical and a mechanical event. Electrical capture is indicated by a pacer spike followed by a corresponding P wave or QRS complex, depending on which chamber is being paced (Figures 5 and 6). If the atrium is paced, the spike appears before the P wave. If the ventricle is paced, the spike occurs before the QRS complex.

Figure 5
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Figure 5

Normal electrical capture, ventricular pacer. Normal ventricular electrical capture is demonstrated by a pacer spike (Vp) followed by a corresponding, widened QRS complex.

Figure 6
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Figure 6

Normal electrical capture, atrial pacer. Normal atrial electrical capture is demonstrated by a pacer spike (Ap) followed by a corresponding P wave.

Because the pacemaker causes the heart to depolarize in an artificial fashion, the path of depolarization is abnormal, resulting in widened P waves and QRS complexes. A pacer spike without a corresponding P wave or QRS complex indicates failure to capture (Figure 7). For a list of potential causes of loss of capture, see Table 3.

View this table:
Table 3

Factors that influence capture and sensing*

Figure 7
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Figure 7

Failure to capture, dual-chamber pacemaker. Failure to capture occurs when a pacer spike is present but is not followed by a corresponding waveform (P wave or QRS complex). Arrow indicates electrical stimulus without ventricular capture.

If loss of capture occurs, the patient is assessed first and then connections and settings are checked to detect disconnections, broken wires, or other mechanical issues. If the patient’s condition is stable, threshold testing is done. If hemodynamic compromise exists, the milliamperage is quickly increased until capture occurs. Turning the patient onto his or her left side may also improve capture by increasing contact between the electrode and myocardial tissue.

Electrical capture alone is inadequate. Adequacy of mechanical capture is assessed by feeling for a pulse or checking blood pressure. Mechanical capture exists when the pacer spike and its corresponding QRS complex are followed by a cardiac contraction.


Sensitivity is the component of pacing that often confounds even experienced clinicians. Nonetheless, sensing merely refers to the ability of the generator to detect and recognize the impulses the myocardial tissue is generating on its own. Intrinsic cardiac activity is usually more organized and global than are paced beats. Intrinsic activity stimulates better contractions, and more effective forward flow of blood, from the chambers of the heart, especially when the atria and ventricles are intrinsically beating synchronously. When atrial beats are unsynchronized or absent, as in atrial fibrillation, atrioventricular block, or sinus arrest, cardiac output decreases because less blood than usual is ejected from the atria during ventricular diastole. This concept is important because almost 30% of normal cardiac output is due to the atrial “kick,” or atrial systole, that occurs during ventricular filling when the 2 chambers perform in sync.

These physiological principles can be directly applied to the use of mechanical pacemakers. Whenever possible, intrinsic beats should be allowed to occur naturally, providing a more global and organized contraction. However, intrinsic beats must be supplemented when the rate is insufficient or conduction of the beats does not generate ventricular contractions. For maximum effectiveness, paced beats and intrinsic beats must be synchronized. To synchronize the beats, the generator first analyzes the intrinsic rhythm and then stimulates the heart only as needed.

Adjusting the sensing level sets the pacer to “look” for intrinsic beats. Pacemaker generators can be programed to deliver an impulse to the ventricle each time an atrial beat is sensed, or they can be set to stimulate only when no intrinsic beat has been detected during a predetermined interval. For example, in a patient with an intrinsic rate of 30 beats/min, the generator may be set to pace both chambers at 80 beats/min. The pacemaker will have no way of determining what the intrinsic rhythm is, or when to stimulate in synchrony, unless the sensitivity is adequately adjusted to provide pacing only on demand.

The sensitivity setting is measured in millivolts and is initially set at about 2 to 5 mV. Failure to sense occurs when the generator does not recognize the heart’s intrinsic impulses (Figure 8). The most common cause of failure to sense is displacement of the electrode (Table 3). Repositioning the patient on his or her left side may improve contact between the electrode and the myocardium. If the response is still inadequate, then the sensitivity must be increased. This increase is accomplished by turning down the millivoltage, allowing the generator to detect beats that occur at lower millivolt levels. Conversely, if the pacemaker is detecting beats that are not actually occurring (inappropriate sensing), then the sensitivity threshold must be increased to block out artifact. This increase is accomplished by turning up the millivoltage.

Figure 8
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Figure 8

Failure to sense, single-chamber atrial pacemaker. Failure to sense occurs when the generator does not detect intrinsic beats and initiates an inappropriate impulse that may or may not capture. Arrow indicates an atrial beat not sensed by the pulse generator, which is followed by a pacer spike.

Care of Patients With Pacemakers

Once the wires are inserted into the pacemaker box, the generator is turned on, settings are adjusted, and pacing should begin. However, if the device is set to pace only when a patient’s heart rate is lower than a certain value, no pacing will occur until the designated limit is reached.

Electrical safety practices are especially important in caring for patients with pacemakers. To prevent micro-shocks, nurses should always wear gloves when handling electrodes and should cover unused transthoracic wires with the fingertip of a disposable glove. Microshocks are associated with ventricular dysrhythmias. The pulse generator must be placed in a location where it will not be dropped on the floor. Lengthy cables attached to the pacemaker need careful attention so that wires are not inadvertently dislodged.

Routine nursing care of patients with temporary pacemakers consists of regular cardiovascular assessment to evaluate pulses, level of consciousness, heart rhythm, pacer activity, and hemodynamic response. Daily management also includes an assessment of the insertion site. Depending on the type of connection, the site will be either a transthoracic or a central venous catheter insertion site. The wires must be secure and not at risk for dislodgement. Nurses should check to see if the wires are intact and should note the number and location. Care for a transvenous wire site is the same as care for a central vascular access site; dressing are changed as prescribed by institutional protocol. Usually, the site is cleaned with povidoneiodine or another antimicrobial agent, and a sterile occlusive dressing is applied, with changes every 48 to 72 hours.

In the first 48 hours after cardiac surgery, epicardial wires usually are under the initial dressing of the chest tube or midsternal incision. Once these bulky dressings are removed, care of the epicardial site should be performed daily whether the site is left open to air or covered with a light dressing. The area is cleaned with isotonic sodium chloride solution and assessed for redness or drainage. The wires must be taped securely to the skin to prevent accidental dislodgement.

Capture and sensitivity threshold testing should be performed every 12 to 24 hours to determine the best settings for the generator (Table 4). As time passes, both transvenous and epicardial wires acquire endothelial sheaths around their tips and thus require more milliamperes to capture and fewer millivolts to sense. The ability to capture and sense is also influenced by patients’ fluid volume status and changes in cardiac tissue. Therefore, thresholds must be tested regularly to ensure proper pacing and prevent loss of capture or inappropriate stimulation. Chambers are tested one at a time; atrial and ventricular chambers should not be tested simultaneously. Threshold testing is generally contraindicated when patients are being paced more than 90% of the time because of the risk of losing capture while the patients are dependent on generator-initiated beats.

View this table:
Table 4

Threshold testing procedure


Competent management of patients with an invasive temporary pacemaker is an important skill for nurses who provide care for critically ill patients with cardiac disease. Such management requires familiarity with normal cardiovascular anatomy and physiology, conduction system defects, and rhythm interpretation. With an understanding of the basic concepts of rate, output, chambers, sensitivity, and capture, pacing can be done with ease. Care of patients with a temporary invasive pacemaker requires monitoring cardiac tissue and hemodynamic status, observing for changes that would indicate the need for modifications in the pacemaker settings. Nursing interventions include physical assessment, care of the insertion site, routine threshold testing, and management of the pulse generator.


  • To purchase reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA 92656. Phone, (800) 809-2273 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, reprints{at}


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  2. Wood M, Belz M, Ellenbogen K. Cardiac pacemakers and implantable defibrillators in the intensive care unit setting. In: Grenvi A, Ayres S, Holbrook P, Shoemaker W, eds. Textbook of Critical Care. 4th ed. Philadelphia, Pa: WB Saunders Co; 2000:1061–1078.

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  7. Paschall FE, McErlean ES. Temporary trans-venous and epicardial pacing. In: Lynn-McHale DJ, Carlson KK, eds. AACN Procedure Manual for Critical Care. 4th ed. Philadelphia, Pa: WB Saunders Co; 2001:285–297.

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