Cardiac Monitor Set-up and Lead Placement

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    Cardiac Monitor Setup and Lead Placement - CE/NCPD

    The content in Clinical Skills is evidence based and intended to be a guide to clinical practice. Always follow your organization’s practice.


    Alterations in electrode position may distort the appearance of the waveform significantly, leading to misdiagnosis or mistreatment.

    Do not use an EASI-derived 12-lead electrocardiogram (ECG) and its measurements for diagnostic interpretations; they are approximations to a conventional 12-lead ECG.


    Continuous cardiac electrophysiologic monitoring is performed routinely for most acute and critically ill patients. A key component of such monitoring is the ECG, which provides a continuous graphic picture of electrical activity generated by the depolarization and repolarization of cardiac tissue. These images may be used for diagnostic, documentation, and treatment purposes. Cardiac electrophysiologic monitoring by hardwire and telemetry is indicated for patients in critical care units, progressive care units, telemetry units, postanesthesia care areas, operating rooms, and emergency departments.

    Hardwire ECG monitors have electrodes and lead wires that are attached directly to the patient. Impulses are transmitted directly from the patient to the monitor. Telemetry systems have electrodes and lead wires that are attached from the patient to a battery pack transmitting impulses to the monitor via radio wave transmission. Telemetry is useful for progressive ambulation and when evaluating a patient's activity tolerance. A disadvantage of telemetry is that ambulation and activity may increase distortion of the ECG pattern, causing artifact.

    Specific areas of the chest are used for placement of electrodes to obtain a view of the electrical activity in a particular area of the heart. ECG monitors use a three-lead or five-lead wire system to provide different views of the heart’s electrical activity. The three-lead system is the oldest and simplest of all cardiac-monitoring lead systems. Only one lead is displayed, lead I, II, III, MCL1, or MCL6. This system is used in many portable monitors and defibrillators. The five-lead system is commonly used in most organizations. This system provides views from the six limb leads (I, II, III, aVR, aVL, aVF) plus one precordial (C or V) lead. Six-lead systems are also now available, and these systems allow monitoring of two precordial leads.

    Standardized placement of leads is important so the information obtained is assessed in a common frame of reference and appropriate judgments may be made on the patient's cardiac status. The two major factors that determine the views of the ECG deflection on the monitor are the location of the electrodes on the body and the direction of the cardiac impulse in relation to the position of the electrode.

    A basic rule of electrocardiography is the rule of electrical flow. This rule notes that if electricity flows toward the positive electrode, an upright pattern is produced on the monitor or graph paper. If the electricity flows away from the positive electrode (i.e., toward the negative electrode), a downward pattern or deflection is produced on the monitor or graph paper.

    Lead wires attached to the patient are coded:

    • +, P (positive) or –, N (negative)
    • RA (right arm)
    • RL (right leg)
    • LA (left arm)
    • LL (left leg)
    • V (precordial vector)
    • C (chest lead)

    Information from the bedside via hardwire or telemetry may be transferred to a central monitor for printing, storage, and analysis. Many central monitoring and bedside monitoring systems provide a continuous readout of two or more leads simultaneously. This readout provides more information and a comparison of the ECG patterns. Optimal lead selection is based on the goals of monitoring for each patient’s situation. The basic goals of ECG monitoring are to monitor patients for rate or rhythm changes, myocardial ischemia and injury (ST monitoring), and to monitor the QT or QTC interval in patients at risk of torsades de pointes.undefined#ref5">5

    Using a traditional 12-lead configuration is impractical for continuous monitoring. However, bedside EASI 12-lead monitoring provides all 12 views of the heart on a continuous basis using only five electrodes. The continuous 12-lead ECG may be accessed for information over a predetermined time per the organization’s practice, greatly expanding the information available from bedside monitors. However, an expert consensus has not been achieved for replacing 12-lead ECGs, the gold standard of cardiac monitoring, with EASI-derived ECGs.


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    • Give developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, preferred learning style, and overall neurologic and psychosocial state.
    • Explain that the patient can move about in bed.
    • Explain the importance of reporting pain, dizziness, palpitations, and chest discomfort.
    • Encourage questions and answer them as they arise.



    1. Assess the patient's cardiovascular status.
    2. Review the patient’s history for cardiac arrhythmias or cardiac problems.


    1. Assist the patient into the supine position.
    2. Assist the patient with removing clothing that covers the chest.
    3. Review the management of clinically appropriate settings for alarms per the organization’s practice.
    4. Check the cables and lead wires for fraying, broken wires, or discoloration.
      If equipment is damaged, obtain alternative equipment and notify the biomedical engineer for repair.
    5. Check individual alarms for accurate settings, proper operation, and detectability.


    1. Ensure that the appropriate patient sector in the central monitoring system has been activated. Refer to the manufacturer’s instructions for use (IFU) for operating the equipment.
      Rationale: When activated, the central monitoring system alarm will sound if problems with the ECG need attention.
      Assess the patient to confirm findings, verify ECG patterns, and evaluate computer interpretations.
    2. Turn on the bedside monitor. For telemetry monitoring, insert a battery into the telemetry transmitter. Refer to the manufacturer's IFU for operating the equipment.
    3. Determine whether the patient is going to be monitored with a three-lead, five-lead, or six-lead system.
      Rationale: The type of system available determines possible placement of electrodes and the leads that may be viewed.
    4. Plug the patient cable into the monitoring system or telemetry transmitter.
    5. Check that the lead wires are plugged into the patient cable correctly and securely.
      1. Manufacturers identify the lead connections by color, letter, or symbol codes.
        1. The right arm lead, marked RA, is usually white.
        2. The left arm lead, marked LA, is usually black.
        3. The left leg lead, marked LL, is usually red.
        4. The right leg lead, marked RL, is usually green.
        5. The chest lead, marked C or V, is usually brown.
          Rationale: This check reduces the chance of disconnection, distortion, or outside interference with the ECG tracing.
      2. Three-lead system:
        1. The negative wire plugs into the opening marked N, (–), or RA (usually white).
        2. The positive wire plugs into the opening marked P, (+), LL, or LA (usually black).
        3. The ground wire plugs into the opening marked G, Neutral, or LL (usually red).
      3. Five-lead system or six-lead system:
        1. The right arm wire plugs into the opening marked RA (usually white).
        2. The left arm wire plugs into the opening marked LA (usually black).
        3. The left leg wire plugs into the opening marked LL (usually red).
        4. The right leg wire plugs into the opening marked RL (usually green).
        5. The chest wire(s) plugs into the opening marked C or V (usually brown).
    6. Select a lead for monitoring considering the constraints of chest wall space for actual electrode placement (e.g., because of dressings or injuries) and the type of information needed.
      1. When using a three-lead system, select a lead:
        1. Lead I
        2. Lead II
        3. Lead III
        4. MCL1
        5. MCL6
          Rationale: The goals of bipolar monitoring using a three-lead system include tracking heart rate, detecting R waves for synchronized cardioversion, and detecting ventricular fibrillation.
      2. When using a five-lead or six-lead system:
        1. Select V1 as the first choice.
        2. If using a five-lead system, substitute V6 for V1 when the patient cannot have an electrode at the sternal border or when the QRS complex amplitude is not adequate for optimized computerized monitoring. If using a six-lead system, select V6 as the second choice.
        3. Select the limb leads appropriate for the clinical situation.
          1. Atrial flutter: Select II, III, or aVF.
          2. Inferior myocardial infarction (MI): Select the lead (II, III, or aVF) with maximum elevation of ST segment on the 12-lead ECG.
          3. Anterior MI: Select the lead (V1 to V6) with maximum elevation of the ST segment on the 12-lead ECG.
          4. After angioplasty: Select the lead (III or aVF) that has the tallest R wave.
          5. Use lead II to diagnose atrial activity and measure heart rate.3
          6. Use V1 and V6 when differentiating normal ventricular beats from ectopic beats.3
          7. For QT-interval monitoring, select the lead in which the end of the T wave is clearly visible.
            Rationale: One limb lead and one precordial lead may be displayed simultaneously with a two-channel system. V1 is the recommended precordial lead. Use leads V1 and V6 for diagnosing arrhythmias with a wide QRS complex (e.g., bundle branch blocks, ventricular pacemaker rhythms, and wide QRS tachycardias).3
        4. Select EASI 12-lead monitoring if a view of 12 leads is needed.
    7. Connect the electrodes to the lead wires before placing the electrodes on the patient.
      Rationale: Placing electrodes on the chest and then attaching the lead wires may be uncomfortable for the patient and may contribute to the development of air bubbles in the electrode gel, which may decrease conduction and distort the ECG image.
    8. Identify the sternal angle or angle of Louis.
      1. Palpate the upper sternum to identify the juncture of the clavicle and the sternum, which is called the suprasternal notch.
      2. Slide the fingers down the center of the sternum to the obvious bony prominence, the sternal angle.
        Rationale: The sternal angle identifies the second rib and provides a landmark for locating the fourth intercostal space (ICS) for accurate placement of electrodes.
      3. Locate the fourth ICS.
    9. Wash the patient's skin with soap and water and dry it briskly with gauze pads or a washcloth.2
      Rationale: Moist skin is not conducive to electrode adherence. Wiping the electrode area with a washcloth or gauze dries and roughens the skin to enhance conduction.2 Some electrodes have a skin abrader on the back that can be used to roughen the surface of the skin.
      Do not use alcohol for skin preparation because it dries the skin.2
      To obtain good skin contact with the electrodes, clip chest hair with surgical clippers as necessary.
    10. Remove the backing from the pregelled electrodes and test the centers of the pads for moistness.
      Rationale: Gel may dry out in storage. Gel should be moist to allow impulse transmission.
      Use electrodes packaged in large quantities shortly after the package is opened because exposure to air over an extended time dries out electrodes and reduces their adhesive and conductive properties. Tightly reseal the package.
    11. Place the electrodes on the patient. Apply electrodes by pressing around their entire edges. Do not press directly on the gel pads.
      Rationale: Electrodes must be placed tightly to prevent external influences from affecting the ECG. Pressing on the gel pad may cause the gel to leak onto the adhesive surfaces and create air pockets that can interfere with transmission.
      Place skin electrodes carefully and consistently to ensure accurate ECG interpretation, which is based on precise placement of skin electrodes on the torso. Inaccurate placement of skin electrodes can distort the appearance of the ECG waveform enough that misdiagnosis and therefore inappropriate treatment can occur.
      Inaccurate placement of electrodes can affect the morphology (shape) of the QRS complex and result in misinterpretation of a rhythm.1
      1. Three-lead system (Figure 1)Figure 1
        1. Apply the RA electrode just below the clavicle and close to the patient’s right shoulder near the junction of the right arm and torso.
        2. Apply the LA electrode just below the clavicle close to the patient’s left shoulder near the junction of the left arm and torso.
        3. Apply the LL electrode below the level of the umbilicus, on the left abdomen.
      2. Three-lead system (MCL1 and MCL6)
        1. Apply the RA electrode close to the patient’s right shoulder near the junction of the right arm and torso.
        2. Apply the LA electrode at the fourth ICS left sternal border.
        3. Apply the LL electrode at the left fifth ICS at the midclavicular line.
        4. Select lead I to obtain MCL1 and lead II to obtain MCL6.
      3. Five-lead system (Figure 1)Figure 1
        1. Apply the RA electrode close to the right shoulder below the clavicle.
        2. Apply the LA electrode close to the left shoulder below the clavicle.
        3. Apply the RL electrode just below the rib cage on the right side.
        4. Apply the LL electrode just below the rib cage on the left side.
        5. Apply the chest lead electrode on the selected site: V1 at the fourth ICS right sternal border or V6 at the fifth ICS left midaxillary line.
          Rationale: Only one precordial lead may be displayed. Placement of the electrode identifies the lead used.
        6. Set the lead selector to monitor the appropriate leads.
      4. Six-lead system
        1. Apply the RA electrode close to the right shoulder below the clavicle.
        2. Apply the LA electrode close to the left shoulder below the clavicle.
        3. Apply the RL electrode just below the rib cage on the right side.
        4. Apply the LL electrode just below the rib cage on the left side.
        5. Apply the chest lead electrode on the V1 position at the fourth ICS right sternal border.
        6. Apply the second chest lead electrode on the V6 position at the fifth ICS left midaxillary line.
          Rationale: Only one precordial lead may be displayed. Placement of the electrode identifies the lead used.
        7. Set the lead selector to monitor the appropriate leads.
      5. EASI system (Figure 2)Figure 2
        1. Place the E (brown) electrode on the lower part of the sternum at the level of the fifth ICS.
        2. Place the A (red) electrode on the left midaxillary line at the level of the fifth ICS.
        3. Place the S (black) electrode on the upper part of the sternum.
        4. Place the I (white) electrode on the right midaxillary line at the level of the fifth ICS.
        5. Place the fifth (ground) electrode anywhere on the patient's chest.
    12. Reduce tension on the lead wires and cables.
      Rationale: Reducing tension alleviates undue stress on wires and cables that may cause interference or faulty recordings.
      1. For hardwire monitoring, fasten the lead wire and patient cable to the patient's gown, making a stress loop.
        Rationale: Creating a stress loop minimizes pulling on the electrodes, which may be uncomfortable for the patient.
      2. For telemetry monitoring, secure the transmitter in a pouch or pocket in the patient's gown.
        Rationale: The transmitter must be secure, so it is not dropped or damaged.
    13. Display the patient’s ECG tracing in two leads, if available.1
    14. Examine the ECG tracing on the monitor for the size of the R and T waves.
      Rationale: The R wave should be approximately twice the height of the other components of the ECG to obtain proper detection by the heart rate counter in the equipment. In many cases, the accuracy of the alarm system depends on the R wave. If the T wave is nearly equal to the R wave, double counting may occur, resulting in false alarms. Manufacturers provide for calibration of the ECG to 1 millivolt, and monitors have size adjustments that may be used to increase or decrease the size of the ECG.
    15. Obtain an ECG strip (Figure 3)Figure 3 and interpret it for rhythm, rate, presence and configuration of the P waves, length of the PR interval, width of the QRS complexes, presence and configuration of the T waves, length of the QT intervals, presence of extra waves (e.g., U waves), and presence of arrhythmias.
      Rationale: This review identifies the normal conduction sequence and abnormalities that may require further evaluation or treatment.
    16. Customize the alarms to meet the patient’s needs.1 Adjust the upper and lower limits based on the patient’s current clinical status and heart rate.
      Rationale: Setting alarm limits activates the bedside or telemetry monitor alarm system. Monitoring systems allow for setting and adjusting alarms at the bedside or at the central monitoring system. The types of alarms may include rate (high or low), abnormal rhythms or complexes, and pacemaker recognition, depending on the manufacturer. Establish policies and procedures for managing the alarms.4
      Never turn off the monitor alarms.
    17. Set the ST segment parameters, if indicated and available.
    18. Set the QT-interval monitoring, if indicated and available.


    1. Evaluate the ECG monitor pattern for the presence of P waves, QRS complexes, a clear baseline, and an absence of artifact or distortion. Obtain a rhythm strip on admission, every shift (per the organization's practice), and with rhythm changes.
      Rationale: A clear pattern is required to make accurate judgments about the patient's status and treatment.
      Reportable conditions: Changes in cardiac ECG complexes, rate, rhythm
    2. Evaluate the ECG pattern on an ongoing basis for arrhythmias, ST changes, and QT or QTC interval. Assess the patient's tolerance of the changes and provide prompt nursing intervention.
      Rationale: Changes in the ECG pattern may indicate significant problems and require immediate intervention or additional diagnostic tests (e.g., 12-lead ECG).
      Reportable conditions: Changes in cardiac rate and rhythm, hemodynamic instability
    3. Review the patient alarms per the organization’s practice.4 Reassess the alarm limits with changes in the patient’s condition.
    4. Monitor the skin for an allergic reaction to the adhesive or gel.
      1. Evaluate skin integrity around the electrodes daily.
        Rationale: Skin integrity must be maintained for a clear picture of the ECG.
      2. Change the electrodes every 242 to 48 hours5 to reduce the number of electrode-related technical alarms.
        Rationale: Replacing electrodes every 242 to 48 hours5 prevents drying of the gel and may decrease the number of false and technical alarms.2
      3. Rotate electrode sites when changing electrodes if sites are irritated.
      4. Change all electrodes if a problem occurs with one.
        Rationale: Electrode resistance changes as the gel dries, so changing all electrodes at once prevents differences in resistance among electrodes.5
        Reportable condition: Alteration in skin integrity
    5. Check electrode placement every shift.
      Rationale: Accurate interpretation of many arrhythmias depends on proper placement of the electrodes.
    6. Change the batteries in the telemetry transmitter per the manufacturer's IFU.
      Rationale: Changing batteries before they are depleted safeguards against an interruption in ECG monitoring.


    • Properly applied electrodes
    • A clear ECG monitor tracing
    • Alarms set appropriately for the patient's clinical status
    • Prompt identification and treatment of arrhythmias


    • Altered skin integrity
    • 60-cycle interference (Figure 4)Figure 4
    • Wandering (erratic) baseline (Figure 5)Figure 5
    • False alarms
    • Artifact or waveform interference (Figure 6)Figure 6


    • Education
    • Cardiovascular assessment
    • Initial or baseline ECG strip, noting the lead, interpretation, any arrhythmias, and interventions
    • Routine ECG strips per the organization’s practice
    • ECG strips recorded when a change occurs in cardiac rate or rhythm, ST segment, QT interval, or lead placement; the patient reports chest pain; and the effects of antiarrhythmic agents are evaluated
    • Unexpected outcomes and related interventions


    1. American Association of Critical-Care Nurses (AACN). (2016, updated 2018). AACN practice alert: Accurate dysrhythmia monitoring in adults. Critical Care Nurse, 38(5), 84.
    2. American Association of Critical-Care Nurses (AACN). (2018). AACN practice alert: Managing alarms in acute care across the life span: Electrocardiography and pulse oximetry. Critical Care Nurse, 38(2), e16-e20.
    3. Hannibal, G.B. (2014). Cardiac monitoring and electrode placement revisited. AACN Advanced Critical Care, 25(2), 188-192. doi:10.1097/NCI.0000000000000020
    4. Joint Commission, The. (2024). National Patient Safety Goals for the hospital program. Retrieved April 11, 2024, from
    5. Sandau, K.E. and others. (2017). Update to practice standards for electrocardiographic monitoring in hospital settings: A scientific statement from the American Heart Association. Circulation, 136(19), e273-e344. doi:10.1161/CIR.0000000000000527

    Adapted from Johnson, K.L. (Ed.). (2024). AACN procedure manual for progressive and critical care (8th ed.). St. Louis: Elsevier.

    Clinical Review: Genevieve L. Hackney, MSN, RN

    Published: May 2024

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