Noninvasive Pacing What You Should Know

1. Noninvasive Pacing � What You Should Know

2. Over the course of this discussion some important concepts in noninvasive pacing will be shared.  Cardiac pacing has been studied by researchers and clinicians since the late 1800s.1 Although utilizing somewhat rudimentary technology, in the 1950's noninvasive pacing was successfully used for the treatment of third degree heart block and recurrent ventricular asystole.2  Since those early years of pacing, improvements in pacing technology have made noninvasive pacing a valuable and respected technique in emergency cardiac care.Over the course of this discussion some important concepts in noninvasive pacing will be shared. Cardiac pacing has been studied by researchers and clinicians since the late 1800s.1 Although utilizing somewhat rudimentary technology, in the 1950's noninvasive pacing was successfully used for the treatment of third degree heart block and recurrent ventricular asystole.2 Since those early years of pacing, improvements in pacing technology have made noninvasive pacing a valuable and respected technique in emergency cardiac care.

3. Evidence Based Medicine What articles or literature support the use of pacing in the Pre-hospital arena?

5. Other Important Papers on Pacing �Prehospital TCP for symptomatic bradycardia� Pacing and Clinical Electrophysiology, 1991 51 pts tot., 27 paced Survival to dischg if palpable pulse on paramedic arrival? 80% in TCP vs 0% (p=0.02) TCP clearly benefits the bradycardic pt with pulse �The Benefits of Electricity: TCP in EMS� Emerg. Med. Svcs, 2002 Informational article supporting the use of TCP in the bradycardic patient and now also in children

6. Last revised in 2005 Emphasis on early pacing for symptomatic bradycardia Initial pacing method of choice in emergency cardiac care Quickly initiated and least invasive The Emergency Cardiac Care Committee of the American Heart Association (AHA) published the new Basic and Advanced Life Support guidelines in the 2005. The guidelines emphasize early pacing for treatment of symptomatic bradycardia. Noninvasive pacing is the initial pacing method of choice in emergency cardiac care. Noninvasive pacing is preferred because it can be implemented quickly and is the least invasive temporary pacing method available.The Emergency Cardiac Care Committee of the American Heart Association (AHA) published the new Basic and Advanced Life Support guidelines in the 2005. The guidelines emphasize early pacing for treatment of symptomatic bradycardia. Noninvasive pacing is the initial pacing method of choice in emergency cardiac care. Noninvasive pacing is preferred because it can be implemented quickly and is the least invasive temporary pacing method available.

7. The heart's natural pacemaker is the sino-atrial (SA) node located in the right atrium. The SA node initiates an impulse 60 to 100 times per minute. The impulse spreads throughout the atria and results in depolarization and contraction of the atrial muscles ejecting blood into the ventricles.  From the atria the impulse travels to the atrioventricular (AV) node where it slows to allow time for the blood to flow into the ventricles from the atria. The impulse continues through the bundle of His, down the right and left bundle branches and through the ventricles via the Purkinje fibers. This causes ventricular depolarization followed by contraction which creates a pulse.The heart's natural pacemaker is the sino-atrial (SA) node located in the right atrium. The SA node initiates an impulse 60 to 100 times per minute. The impulse spreads throughout the atria and results in depolarization and contraction of the atrial muscles ejecting blood into the ventricles. From the atria the impulse travels to the atrioventricular (AV) node where it slows to allow time for the blood to flow into the ventricles from the atria. The impulse continues through the bundle of His, down the right and left bundle branches and through the ventricles via the Purkinje fibers. This causes ventricular depolarization followed by contraction which creates a pulse.

8. May occur anywhere in the system The farther down the system � the slower the heart rate Multiple causes Results bradycardia asystole Any portion of the specialized conduction tissue in the heart may fail. If the SA node fails to generate an impulse, conduction tissue farther down the line will initiate one. Generally speaking, the farther down the conduction system the failure occurs, the slower the heart rate. There are several reasons why the normal conductive tissue may fail. Some are coronary artery disease, acute myocardial infarction, drug or toxin overdose, acute renal failure, trauma or hypoxia. For example, if blood flow is interrupted such as in an acute MI and tissue death results, initiation of impulses may not occur from that area and conductive tissue that is not affected may need to take over.  This results in slow rates (bradycardia) or in extreme cases cardiac standstill (asystole). Any portion of the specialized conduction tissue in the heart may fail. If the SA node fails to generate an impulse, conduction tissue farther down the line will initiate one. Generally speaking, the farther down the conduction system the failure occurs, the slower the heart rate. There are several reasons why the normal conductive tissue may fail. Some are coronary artery disease, acute myocardial infarction, drug or toxin overdose, acute renal failure, trauma or hypoxia. For example, if blood flow is interrupted such as in an acute MI and tissue death results, initiation of impulses may not occur from that area and conductive tissue that is not affected may need to take over. This results in slow rates (bradycardia) or in extreme cases cardiac standstill (asystole).

9. Atropine Noninvasive pacing (Class 1 intervention) Dopamine Epinephrine Noninvasive pacing is included in the ACLS treatment algorithm for bradycardia as a Class I intervention (definitely helpful).4  Noninvasive pacing is indicated especially if the patient is unresponsive to atropine. Pacing should not be delayed awaiting IV access or for atropine to take effect.4 Noninvasive pacing is included in the ACLS treatment algorithm for bradycardia as a Class I intervention (definitely helpful).4 Noninvasive pacing is indicated especially if the patient is unresponsive to atropine. Pacing should not be delayed awaiting IV access or for atropine to take effect.4

10. Pacing is no longer recommended for aystole Poor survival rates for prehospital patients with asystole were postulated to be related in part to long patient down times prior to the initiation of pacing and the late application of pacing in treatment protocols.5 Investigators studied both variables and found that poor survival rates for asystolic cardiac arrest can be attributed to a hypoxic myocardium which is refractory to treatment over time.6 If pacing is to be effective, it must be implemented early. Pacing should be considered for patients in cardiac arrest due to drug overdose or patients with pulseless electrical activity due to acidosis or electrolyte abnormalities. Pacing patients as soon as possible while correcting the acidosis or abnormalities may stimulate effective myocardial contractions until the conduction system can recover.4Poor survival rates for prehospital patients with asystole were postulated to be related in part to long patient down times prior to the initiation of pacing and the late application of pacing in treatment protocols.5 Investigators studied both variables and found that poor survival rates for asystolic cardiac arrest can be attributed to a hypoxic myocardium which is refractory to treatment over time.6 If pacing is to be effective, it must be implemented early. Pacing should be considered for patients in cardiac arrest due to drug overdose or patients with pulseless electrical activity due to acidosis or electrolyte abnormalities. Pacing patients as soon as possible while correcting the acidosis or abnormalities may stimulate effective myocardial contractions until the conduction system can recover.4

11. MVEMSA Pacing Protocol INDICATIONS: Symptomatic Bradycardia 3rd degree Complete Heart Block or 2nd degree Mobitz type 2 RELATIVE CONTRAINDICATIONS: Hypothermia Hemodynamically stable awake patients.� Non-intact skin at the site of the electrode placement

12. Temporary Pacing Techniques Epicardial Transesophageal Trancutaneous

13. Noninvasive Pacing Self-adhesive electrodes applied to the skin Advantages easily initiated by nurse, paramedic and MD not invasive/cost effective used when invasive pacing is contraindicated / undesirable Disadvantages discomfort

14. Applications for Noninvasive Pacing Emergency Use Alternative to invasive pacing Standby Use

15. Emergency Use of Noninvasive Pacing Therapeutic bridge to stabilize the patient and plan further care symptomatic bradycardia unresponsive to drugs cardiac arrest

16. Standby Use of Noninvasive Pacing Patient is clinically stable but may decompensate cardiac patient undergoing surgery acute MI with heart block permanent pacemaker surgery cardiac catheterization/angioplasty post cardioversion bradycardias We WILL NOT be using Pacing for these purposes!

17. Preparing the patient and family ECG electrode placement Pacing electrode placement Selecting the rate, mode and current Assessing for capture Let's discuss these basic elements of the pacing procedure: preparing the patient and family, ECG and pacing electrode placement, selecting the rate, mode and current, and assessing for capture. We'll discuss each of these steps in some detail. Let's discuss these basic elements of the pacing procedure: preparing the patient and family, ECG and pacing electrode placement, selecting the rate, mode and current, and assessing for capture. We'll discuss each of these steps in some detail.

18. Explain procedure discomfort with cutaneous nerve and skeletal muscle stimulation Sedation or analgesia often needed Patient preparation is key to the success of pacing. Along with a general explanation of the procedure, discussing the discomfort and the skeletal muscle contractions associated with pacing will help prepare the patient and family. The level of discomfort varies according to several factors: the patient and their tolerance of pain, the polarity of the electrodes, and the level of current needed for capture.  The discomfort of pacing has two components: cutaneous nerve stimulation which result in tingling, stinging or burning sensations and the skeletal muscle contractions which results in tapping, twitching or thudding sensations. Most patients will better tolerate the procedure with sedation or analgesia.Patient preparation is key to the success of pacing. Along with a general explanation of the procedure, discussing the discomfort and the skeletal muscle contractions associated with pacing will help prepare the patient and family. The level of discomfort varies according to several factors: the patient and their tolerance of pain, the polarity of the electrodes, and the level of current needed for capture. The discomfort of pacing has two components: cutaneous nerve stimulation which result in tingling, stinging or burning sensations and the skeletal muscle contractions which results in tapping, twitching or thudding sensations. Most patients will better tolerate the procedure with sedation or analgesia.

19. Skin prep remove excessive chest hair clean, dry, and gently abrade skin Place ECG electrodes away from pacing electrodes Use quality ECG electrodes ECG signal quality is important during demand pacing for accurate sensing as well as interpretation of pacing results. In order to ensure a quality ECG signal, skin preparation under the ECG electrodes is key. Poor ECG signal quality during pacing may be avoided or reduced if the skin under the ECG electrodes is clean and dry. Excessive chest hair should be removed. Briskly rubbing the skin before placing the ECG electrodes will improve the monitoring signal quality. In order to obtain a clear ECG signal, it is important to place the ECG electrodes as far away from the pacing electrodes as possible. ECG signal quality is important during demand pacing for accurate sensing as well as interpretation of pacing results. In order to ensure a quality ECG signal, skin preparation under the ECG electrodes is key. Poor ECG signal quality during pacing may be avoided or reduced if the skin under the ECG electrodes is clean and dry. Excessive chest hair should be removed. Briskly rubbing the skin before placing the ECG electrodes will improve the monitoring signal quality. In order to obtain a clear ECG signal, it is important to place the ECG electrodes as far away from the pacing electrodes as possible.

20. Skin prep important clip excessive chest hair clean skin with soap and water dry skin and gently abrade Place pacing electrodes on clean, dry skin Skin preparation under the pacing electrode is also important. Skin preparation for pacing is often hastily done due to the emergent nature of the procedure. If chest hair under the pacing electrode is excessive, it should be removed. In concious patients, clip rather than shave the hair as tiny nicks in the skin from shaving may greatly increase patient discomfort. Excessive chest hair results in higher patient impedance and in extreme cases can result in �pacing leads off� alarms. Ideally, the skin under the pacing electrode should be cleaned with soap and water, dried and then gently abraded. Alcohol, benzoin, or antiperspirant should not be used to prep the skin. The pacing electrode should then be placed securely on the clean, dry skin.Skin preparation under the pacing electrode is also important. Skin preparation for pacing is often hastily done due to the emergent nature of the procedure. If chest hair under the pacing electrode is excessive, it should be removed. In concious patients, clip rather than shave the hair as tiny nicks in the skin from shaving may greatly increase patient discomfort. Excessive chest hair results in higher patient impedance and in extreme cases can result in �pacing leads off� alarms. Ideally, the skin under the pacing electrode should be cleaned with soap and water, dried and then gently abraded. Alcohol, benzoin, or antiperspirant should not be used to prep the skin. The pacing electrode should then be placed securely on the clean, dry skin.

21. Most common placement Preferred Improves conduction to myocardium The most common pacing electrode placement is anterior-posterior. If using �pace only� electrodes the anterior-posterior placement does not interfere with placement of defibrillation paddles. In female patients place the anterior electrode directly below the breast tissue.The most common pacing electrode placement is anterior-posterior. If using �pace only� electrodes the anterior-posterior placement does not interfere with placement of defibrillation paddles. In female patients place the anterior electrode directly below the breast tissue.

22. The anterior electrode is placed near the V2- V3 position.  Avoid placement over the nipple or sternum, if possible.The anterior electrode is placed near the V2- V3 position. Avoid placement over the nipple or sternum, if possible.

23. The posterior electrode is placed at the same level as the anterior electrode beneath the scapula, left and lateral to the spine. The posterior electrode is placed at the same level as the anterior electrode beneath the scapula, left and lateral to the spine.

24. This is a lateral view of anterior-posterior electrode placement. The anterior-posterior placement resembles a �heart sandwich�.This is a lateral view of anterior-posterior electrode placement. The anterior-posterior placement resembles a �heart sandwich�.

25. Alternate placement Convenient placement in cardiac arrest Usually the SECOND choice The anterior-lateral position may also be used for pacing. Capture thresholds and capture rates are similar for anterior-lateral and anterior-posterior placement. This placement allows easy access to the patient's torso and is usually more convenient in cardiac arrest. If using �pace only� electrodes, the anterior-lateral placement may interfere with placement of defibrillation paddles. If using �pace-defibrillation� combination electrodes, the anterior-lateral placement allows easy access. Follow manufacturer's recommendations for placement of the pacing electrodes and cables. Do not reverse the recommended placement for the pacing electrodes or pacing cable. If the electrodes or cables are reversed failure to capture or extremely high capture thresholds, may result.10 The anterior-lateral position may also be used for pacing. Capture thresholds and capture rates are similar for anterior-lateral and anterior-posterior placement. This placement allows easy access to the patient's torso and is usually more convenient in cardiac arrest. If using �pace only� electrodes, the anterior-lateral placement may interfere with placement of defibrillation paddles. If using �pace-defibrillation� combination electrodes, the anterior-lateral placement allows easy access. Follow manufacturer's recommendations for placement of the pacing electrodes and cables. Do not reverse the recommended placement for the pacing electrodes or pacing cable. If the electrodes or cables are reversed failure to capture or extremely high capture thresholds, may result.10

26. The lateral electrode is placed in the midaxillary line lateral to the nipple (V6 position). The anterior electrode is placed in the right subclavicular area lateral to the sternum. The lateral electrode is placed in the midaxillary line lateral to the nipple (V6 position). The anterior electrode is placed in the right subclavicular area lateral to the sternum.

27. Demand Non-demand (asynchronous or fixed) Depending on the manufacturer, noninvasive pacemakers may offer two modes: demand or non-demand (sometimes referred to as asynchronous or fixed rate). Depending on the manufacturer, noninvasive pacemakers may offer two modes: demand or non-demand (sometimes referred to as asynchronous or fixed rate).

28. MVEMSA Protocol Assemble the required equipment. Explain the procedure to the patient. Connect the patient to a cardiac monitor and obtain a rhythm strip. Obtain baseline vital signs.

29. MVEMSA Protocol Provide for patient sedation using Versed 2mg slow IV push, titrate in 1 mg increments, to a maximum of 6mg. DO NOT delay pacing to give sedation if the patient is critically ill and such delay may cause a detriment in patient�s care. Apply pacing electrodes (avoid large muscle masses) and attach the pacing cable and pacing device, per manufacturer�s recommendations. Select the pacing mode to demand or non-demand mode, if applicable. Set the pacing rate to 80 BPM. Set the milliamps (mA) at zero.

30. MVEMSA Protocol Activate the pacing device and increase the milliamps as tolerated (observe the patient and ECG) until capture is achieved (capture is the point when the pacemaker produces a pulse with each QRS complex). Obtain rhythm strips as appropriate. Continue monitoring the patient and anticipate further therapy.

31. Delivers impulse only when needed Sensing inhibits pacemaker Not used in Pre-hospital environment In the demand mode, the pacemaker delivers an impulse only when it is needed. The demand pacemaker searches for intrinsic cardiac activity. If it does not detect or �sense� a beat within a designated interval it will deliver a pacing impulse. When it detects an intrinsic beat it will reset its timer and continue the search for intrinsic cardiac activity. Some pacemakers mark intrinsic electrical activity by a square or triangle on the QRS complex (sense mark). Proper sensing in demand mode pacing should be verified at the initiation of pacing and at frequent intervals during pacing.  Pace markers (sometimes represented by a spike) represent the time of current delivery. Some manufacturers may mark pace pulse timing by arrows at the bottom of ECG strip. Demand pacing is the preferred method of pacing. This mode allows the patient's intrinsic rhythm to take over when it exceeds the set pacing rate.In the demand mode, the pacemaker delivers an impulse only when it is needed. The demand pacemaker searches for intrinsic cardiac activity. If it does not detect or �sense� a beat within a designated interval it will deliver a pacing impulse. When it detects an intrinsic beat it will reset its timer and continue the search for intrinsic cardiac activity. Some pacemakers mark intrinsic electrical activity by a square or triangle on the QRS complex (sense mark). Proper sensing in demand mode pacing should be verified at the initiation of pacing and at frequent intervals during pacing. Pace markers (sometimes represented by a spike) represent the time of current delivery. Some manufacturers may mark pace pulse timing by arrows at the bottom of ECG strip. Demand pacing is the preferred method of pacing. This mode allows the patient's intrinsic rhythm to take over when it exceeds the set pacing rate.

32. Delivers current at selected rate and ignores intrinsic beats Backup mode for oversensing and motion artifact A non-demand pacemaker delivers electrical stimuli at the selected pace rate regardless of the patient's intrinsic cardiac activity. This mode of pacing may be used when oversensing occurs and other troubleshooting measures are unsuccessful. Also non-demand mode may be needed if motion artifact interferes with proper sensing. During non-demand pacing, competition between the pacing stimuli and the patient's intrinsic beats may occur. Although the pacing stimulus may fall on a T wave, it appears the risk of inducing ventricular tachycardia or ventricular fibrillation is more of a theoretical than an actual risk. In canine studies, researchers have reported the thresholds for ventricular fibrillation are above the maximum output of the noninvasive pacemaker.9A non-demand pacemaker delivers electrical stimuli at the selected pace rate regardless of the patient's intrinsic cardiac activity. This mode of pacing may be used when oversensing occurs and other troubleshooting measures are unsuccessful. Also non-demand mode may be needed if motion artifact interferes with proper sensing. During non-demand pacing, competition between the pacing stimuli and the patient's intrinsic beats may occur. Although the pacing stimulus may fall on a T wave, it appears the risk of inducing ventricular tachycardia or ventricular fibrillation is more of a theoretical than an actual risk. In canine studies, researchers have reported the thresholds for ventricular fibrillation are above the maximum output of the noninvasive pacemaker.9

33. Assure proper QRS sensing Set pace rate high enough for adequate perfusion Increase current (mA) until electrical capture Pacing current should remain at zero milliamperes (mA) until the pacing mode has been selected and proper sensing (if demand pacing is selected) has been verified. The pacing rate should be selected with a rate high enough for adequate perfusion (common range in adults: 60-90 PPM).  Current may then be adjusted upward until capture is identified. Pacing current should remain at zero milliamperes (mA) until the pacing mode has been selected and proper sensing (if demand pacing is selected) has been verified. The pacing rate should be selected with a rate high enough for adequate perfusion (common range in adults: 60-90 PPM). Current may then be adjusted upward until capture is identified.

34. Access Pacer (Green) mode (Zoll) The Pacer (Green) mode is accessed by turning the Selector Switch counter-clockwise Milliamps are the type of current which are utilized in this mode No AED capability or ANALYZE button can be used in this mode

35. Pacer Mode: Rate Dial Pacer markers (PPM) indicate the rate set to attempt to capture the ventricle Default settings of 70 PPM and 0 mA are displayed upon access of Pacer Mode To increase or decrease pacer marker (PPM) turn the Pacer Rate Dial

36. Pacer Mode: Output Dial Turn the Pacer Output dial to adjust the level of discharged milliamps. If capture is achieved, the PPM will have a wide complex reflecting ventricular contraction following the thin PPM rate marker

37. Electrical capture depolarization of the ventricles confirmed by ECG display Mechanical capture contraction of the myocardium confirmed by pulse and improved cardiac output Both must occur to benefit the patient Electrical capture occurs when a pacing stimulus leads to depolarization of the ventricles. It is confirmed by ECG changes displayed on the monitor. Mechanical capture is the contraction of the myocardium and is evidenced by presence of a pulse and signs of improved cardiac output.  Both electrical and mechanical capture must occur to benefit the patient.Electrical capture occurs when a pacing stimulus leads to depolarization of the ventricles. It is confirmed by ECG changes displayed on the monitor. Mechanical capture is the contraction of the myocardium and is evidenced by presence of a pulse and signs of improved cardiac output. Both electrical and mechanical capture must occur to benefit the patient.

38. Depolarization is initiated in the ventricle. Electrical capture is represented by a widening of the QRS and a tall, broad T wave which is typical of a beat originating in the ventricle. The deflection of the captured beat may be positive or negative. It resembles the captured beats seen in permanent or temporary ventricular pacing. The pace marker or �spike� is a software generated marker which represents the time of current delivery. Its design may vary among manufacturers. The arrows below the ECG tracing indicate the timing of current delivery. Pacing annotation varies among manufacturers. Electrical capture is seen here as negatively deflected QRS complexes and tall T waves. First beat seen is the intrinsic beat. The rest are captured beats.Depolarization is initiated in the ventricle. Electrical capture is represented by a widening of the QRS and a tall, broad T wave which is typical of a beat originating in the ventricle. The deflection of the captured beat may be positive or negative. It resembles the captured beats seen in permanent or temporary ventricular pacing. The pace marker or �spike� is a software generated marker which represents the time of current delivery. Its design may vary among manufacturers. The arrows below the ECG tracing indicate the timing of current delivery. Pacing annotation varies among manufacturers. Electrical capture is seen here as negatively deflected QRS complexes and tall T waves. First beat seen is the intrinsic beat. The rest are captured beats.

39. 100% electrical capture.100% electrical capture.

40. 100% electrical capture100% electrical capture

41. Interpretation of electrical capture may be challenging. Intermittent electrical capture is seen here along with artifact. Electrical capture is represented here as wide, positively deflected QRS complexes followed by broad T waves. Note that two of the intrinsic QRS complexes are not sensed. These complexes fall in the pacemaker's refractory period. Many patients achieve capture between 50 and 100 mA; however, individual thresholds vary markedly. Hypoxia, acidosis, recent thoracic surgery, pericardial tamponade, emphysema, air or fluid in the chest, mild hypothermia, ischemia or other physiological variables may lead to higher thresholds.11  Current must be adjusted upward until capture is achieved. Capture thresholds are not related to body surface area or weight.  The most common error in pacing is not advancing the current high enough to achieve capture. Interpretation of electrical capture may be challenging. Intermittent electrical capture is seen here along with artifact. Electrical capture is represented here as wide, positively deflected QRS complexes followed by broad T waves. Note that two of the intrinsic QRS complexes are not sensed. These complexes fall in the pacemaker's refractory period. Many patients achieve capture between 50 and 100 mA; however, individual thresholds vary markedly. Hypoxia, acidosis, recent thoracic surgery, pericardial tamponade, emphysema, air or fluid in the chest, mild hypothermia, ischemia or other physiological variables may lead to higher thresholds.11 Current must be adjusted upward until capture is achieved. Capture thresholds are not related to body surface area or weight. The most common error in pacing is not advancing the current high enough to achieve capture.

42. 2nd and 4th beats are �captured�2nd and 4th beats are �captured�

43. Determining Mechanical Capture Check pulse (Doppler helpful) Look for increase in blood pressure Check on opposite side of pacing if possible. Use Doppler if possible.Check on opposite side of pacing if possible. Use Doppler if possible.

44. Determining Mechanical Capture Use of pulse oximetry during pacing may assist in determining capture PLEASE DON�T FORGET THIS IMPORTANT POINT!

45. During routine monitoring the ECG electrodes pick up small electrical signals from the heart which are then amplified and displayed on the ECG display.During pacing, strong electrical current is transmitted across the chest and to the heart muscle. The ECG electrodes pick up the energy caused by this current. An artifact signal may be displayed on the screen. In extreme cases the artifact could mask an underlying rhythm such as ventricular fibrillation as well as distort the response to pacing.4This artifact is present with all noninvasive pacemakers. In order to minimize this artifact on the ECG display, a brief period of the ECG is blanked. The blanked period usually begins when the pace pulse is delivered and lasts 40 to 80 milliseconds, depending on the manufacturer.Although this brief loss of data may not seem ideal, having an interpretable ECG signal is clearly beneficial. If this artifact were not blanked there would be large offsets obliterating the ECG signal on the display screen. For example, if monitoring is attempted with a monitor that is not integral to the pacemaker, the signal on the monitor may be greatly distorted. During routine monitoring the ECG electrodes pick up small electrical signals from the heart which are then amplified and displayed on the ECG display.During pacing, strong electrical current is transmitted across the chest and to the heart muscle. The ECG electrodes pick up the energy caused by this current. An artifact signal may be displayed on the screen. In extreme cases the artifact could mask an underlying rhythm such as ventricular fibrillation as well as distort the response to pacing.4This artifact is present with all noninvasive pacemakers. In order to minimize this artifact on the ECG display, a brief period of the ECG is blanked. The blanked period usually begins when the pace pulse is delivered and lasts 40 to 80 milliseconds, depending on the manufacturer.Although this brief loss of data may not seem ideal, having an interpretable ECG signal is clearly beneficial. If this artifact were not blanked there would be large offsets obliterating the ECG signal on the display screen. For example, if monitoring is attempted with a monitor that is not integral to the pacemaker, the signal on the monitor may be greatly distorted.

46. Artifact may mimic electrical capture If ECG signal distortion is severe it may be necessary to select another lead or reposition the ECG electrodes far away from the pacing electrodes.  This ECG strip demonstrates pace pulses followed by artifact. The artifact resembles QRS complexes. Electrical capture, which would be represented by a wide QRS and tall T wave, is not seen. Artifact may increase in size as current is increased.If ECG signal distortion is severe it may be necessary to select another lead or reposition the ECG electrodes far away from the pacing electrodes. This ECG strip demonstrates pace pulses followed by artifact. The artifact resembles QRS complexes. Electrical capture, which would be represented by a wide QRS and tall T wave, is not seen. Artifact may increase in size as current is increased.

47. Artifact may mimic electrical capture Despite the presence of the blanking period all of the ECG artifact may not be completely blanked and a portion of it may be seen immediately following the pace stimulus (pace pulse).  The morphology of artifact is variable. At times it may resemble a QRS complex and is sometimes confused with electrical capture. It is important to distinguish between electrical capture and artifact during pacing. Traces displaying ECG signal distortion return to the baseline without evidence of a T wave. This ECG strip demonstrates pace pulses followed by artifact. No electrical capture is seen.Despite the presence of the blanking period all of the ECG artifact may not be completely blanked and a portion of it may be seen immediately following the pace stimulus (pace pulse). The morphology of artifact is variable. At times it may resemble a QRS complex and is sometimes confused with electrical capture. It is important to distinguish between electrical capture and artifact during pacing. Traces displaying ECG signal distortion return to the baseline without evidence of a T wave. This ECG strip demonstrates pace pulses followed by artifact. No electrical capture is seen.

48. ECG electrodes pick up artifact from pacing current Artifact is sometimes displayed on monitor May mask VF and distort response to pacing Blanking period attempts to filter out artifact and limit distortion of ECG signal

49. Discomfort Failure to capture Undersensing Oversensing Let's discuss some ways to effectively troubleshoot common pacing problems: discomfort, failure to capture, undersensing, and oversensing.Let's discuss some ways to effectively troubleshoot common pacing problems: discomfort, failure to capture, undersensing, and oversensing.

50. Explain procedure Reposition anterior electrode Use sedation or analgesia As with any procedure, a simple explanation of how pacing works and why it is necessary may help the conscious patient and their family cope with the procedure. If using anterior-posterior placement, moving the anterior electrode to the V6 position may also reduce discomfort in certain patients. Use of analgesia with incremental doses of a narcotic, or sedation with a benzodiazepine may be needed.4As with any procedure, a simple explanation of how pacing works and why it is necessary may help the conscious patient and their family cope with the procedure. If using anterior-posterior placement, moving the anterior electrode to the V6 position may also reduce discomfort in certain patients. Use of analgesia with incremental doses of a narcotic, or sedation with a benzodiazepine may be needed.4

51. Increase current Reposition electrode across precordium Correct metabolic acidosis, hypoxia Check pacemaker function The most common reason for not obtaining capture is failure to increase the current sufficiently to electrically stimulate the heart. Increase the current as much as needed for electrical capture. Capture thresholds vary markedly among individuals and are not related to body weight or body surface area. Moving the electrode across the precordium may facilitate capture. Determine if underlying pathophysiology of the patient, such as metabolic acidosis or hypoxia, is preventing cardiac response to pacing.  The pacemaker including the electrodes and cable may need to be examined for proper function. Attempting another form of temporary pacing, if available, may be necessary. The most common reason for not obtaining capture is failure to increase the current sufficiently to electrically stimulate the heart. Increase the current as much as needed for electrical capture. Capture thresholds vary markedly among individuals and are not related to body weight or body surface area. Moving the electrode across the precordium may facilitate capture. Determine if underlying pathophysiology of the patient, such as metabolic acidosis or hypoxia, is preventing cardiac response to pacing. The pacemaker including the electrodes and cable may need to be examined for proper function. Attempting another form of temporary pacing, if available, may be necessary.

52. Hypoxia Acidosis Air, fluid in the chest Emphysema, pericardial effusion Positive pressure ventilation Ischemia Mild Hypothermia

53. Increase ECG size Select different ECG lead Reposition ECG electrodes Re-prep skin and replace ECG electrodes Sensing is the ability of the pacemaker to identify electrical activity which stems from the myocardium. If the pacemaker does not sense intrinsic activity, it will deliver current.  Troubleshooting measures include selecting a different lead or repositioning the ECG electrodes. All these troubleshooting measures focus on changing the ECG signal appearance to the monitor so proper sensing may occur.Sensing is the ability of the pacemaker to identify electrical activity which stems from the myocardium. If the pacemaker does not sense intrinsic activity, it will deliver current. Troubleshooting measures include selecting a different lead or repositioning the ECG electrodes. All these troubleshooting measures focus on changing the ECG signal appearance to the monitor so proper sensing may occur.

54. Decrease ECG size Select different ECG lead Reposition ECG electrodes Select non-demand mode if available Inappropriate inhibition of the pace pulse delivery may occur with oversensing. Also, the set pacing rate may not be maintained. Oversensing can normally be corrected by decreasing the ECG size. If oversensing persists, change to a different ECG lead or reposition the ECG leads. It may be necessary to select non-demand pacing mode if all other troubleshooting measures fail.Inappropriate inhibition of the pace pulse delivery may occur with oversensing. Also, the set pacing rate may not be maintained. Oversensing can normally be corrected by decreasing the ECG size. If oversensing persists, change to a different ECG lead or reposition the ECG leads. It may be necessary to select non-demand pacing mode if all other troubleshooting measures fail.

55. The typical patient who will benefit from pacing is one with a primary conduction disturbance or transient disorder such as a post-cardioversion bradycardia or drug ingestion. Early intervention is key. Pacing is less likely to benefit patients that have been in prolonged cardiac arrest or have extensive myocardial damage or cardiac trauma. Pacing will not convert rhythms such as ventricular fibrillation, atrial fibrillation or atrial flutter. The typical patient who will benefit from pacing is one with a primary conduction disturbance or transient disorder such as a post-cardioversion bradycardia or drug ingestion. Early intervention is key. Pacing is less likely to benefit patients that have been in prolonged cardiac arrest or have extensive myocardial damage or cardiac trauma. Pacing will not convert rhythms such as ventricular fibrillation, atrial fibrillation or atrial flutter.

56. Valued and respected technique in emergency cardiac care Basic principles of invasive pacing apply to noninvasive pacing Allows rapid initiation of emergency pacing In summary, noninvasive pacing is a valued and respected therapy. The basic principles of invasive pacing apply to noninvasive pacing. Noninvasive pacing allows rapid initiation of emergency pacing.In summary, noninvasive pacing is a valued and respected therapy. The basic principles of invasive pacing apply to noninvasive pacing. Noninvasive pacing allows rapid initiation of emergency pacing.

57. Noninvasive pacing �buys time� to stabilize the patient and plan further care.Noninvasive pacing �buys time� to stabilize the patient and plan further care.