A D V A N C E D P A C I N G

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Pacemakers

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  • A D V A N C E D P A C I N G

    1. 1. ADVANCED PACING Understanding and Troubleshooting Pacemakers Sherry L. Knowles, RN, CCRN, CRNI
    2. 2. Objectives <ul><li>Understand the different pacemaker modes according to the NASPE/BPEG (NGB) universal code. </li></ul><ul><li>Recognize common pacemaker complications in a cardiac tracing. </li></ul><ul><li>Differentiate between failure to pace, loss of capture, under sensing and over sensing. </li></ul><ul><li>List appropriate nursing actions for common pacemaker complications. </li></ul><ul><li>Understand routine pacemaker settings and thresholds. </li></ul><ul><li>Identify the different types of pacemakers. </li></ul><ul><li>Understand and recognize pacemaker syndrome. </li></ul><ul><li>Be familiar with the proper use of a pacemaker magnet. </li></ul><ul><li>Understand routine nursing management of a patient with a pacemaker. </li></ul><ul><li>Recognize battery failure in temporary and permanent pacemaker devices. </li></ul>At the end of this presentation, the view will be able to:
    3. 3. Pacemaker
    4. 4. Nursing Action
    5. 5. Indications for Pacing
    6. 6. Indications for Pacing <ul><li>Symptomatic Bradycardia </li></ul><ul><li>Heart Blocks </li></ul><ul><ul><li>Second Degree AV Block – symptomatic </li></ul></ul><ul><ul><li>Complete AV Block </li></ul></ul><ul><li>Sick Sinus Syndrome </li></ul><ul><li>Overdrive Pacing </li></ul><ul><li>Malfunctioning Pacemaker </li></ul><ul><li>Support During Electrolyte or Acid-Base Disturbances </li></ul><ul><li>To Improve Hemodynamics </li></ul><ul><li>Support During Procedures </li></ul><ul><li>Backup Support With Drug Therapy </li></ul>
    7. 7. Types of Pacing <ul><li>Temporary Pacing </li></ul><ul><ul><li>Transvenous </li></ul></ul><ul><ul><li>Transcutaneous </li></ul></ul><ul><ul><li>Epicardial </li></ul></ul><ul><li>Permanent Pacing </li></ul><ul><ul><li>High/Low Rate Setting </li></ul></ul><ul><ul><li>PR and AV Intervals </li></ul></ul><ul><ul><li>Rate Response Pacing </li></ul></ul><ul><ul><li>Mode Switching </li></ul></ul><ul><li>Fixed Rate </li></ul><ul><ul><li>Controlled </li></ul></ul><ul><ul><li>Asynchronous </li></ul></ul><ul><li>Demand </li></ul><ul><ul><li>Backup </li></ul></ul><ul><ul><li>Synchronous </li></ul></ul><ul><li>AV Sequential </li></ul><ul><ul><li>Dual Chamber Pacing </li></ul></ul><ul><ul><li>Atrial & Ventricular wires </li></ul></ul>
    8. 8. Pacemaker Types
    9. 9. Epicardial Pacing
    10. 10. Transcutaneous Pacing
    11. 11. Insertion Complications <ul><li>Dysrhythmias </li></ul><ul><li>Perforation </li></ul><ul><li>Pneumothorax </li></ul><ul><li>Hematoma </li></ul><ul><li>Hemorrhage </li></ul><ul><li>Tamponade </li></ul><ul><li>Pericardial Friction Rub </li></ul><ul><li>Vein Thrombosis </li></ul><ul><li>Infection </li></ul><ul><li>Inadvertent Arterial Puncture </li></ul><ul><li>Diaphragmatic Stimulation </li></ul>
    12. 12. Modes of Pacing R D D D Chamber Paced O = None A = Atrium V = Ventricle D = Dual ( A + V) Chamber Sensed O = None A = Atrium V = Ventricle D = Dual ( A + V) Response to Sensing O = None T = Triggered I = Inhibited D = Dual ( T + I) Programmability O = None P = Simple Programmable M= Multiple Programmable R = Rate Modulation
    13. 13. Pacemaker Modes <ul><li>AOO: Atrial pacing, no sensing, atrial fixed rate </li></ul><ul><li>VOO: Ventricular pacing, no sensing, ventricular fixed rate. </li></ul><ul><li>DOO: AV pacing, no sensing, AV fixed rate. </li></ul><ul><li>AAI: Atrial Pacing, atrial sensing, inhibited response to sensing. Atrial demand pacing. </li></ul><ul><li>VVI: Ventricular pacing, ventricular sensing, inhibited response to sensing. Ventricular demand pacing. </li></ul><ul><li>DDI: A pacemaker that senses and stimulates both atrium and ventricle. The stimulation rate is fixed. </li></ul>AOO VOO DOO AAI VVI DDI
    14. 14. Pacemaker Modes <ul><li>SSI: Single chamber pacing (atrial or ventricular), same chamber sensing, inhibited response to sensing. A pacemaker that senses and stimulates one chamber at one rate. </li></ul><ul><li>AAT: Atrial pacing, atrial sensing, triggered response to sensing. Atrial demand pacing. </li></ul><ul><li>VVT: Ventricular pacing, ventricular pacing, triggered response to sensing. Ventricular demand pacing. </li></ul><ul><li>VAT: Ventricular pacing, atrial sensing, triggered response to sensing. The ventricular stimulus will fire at a set interval after sensing a spontaneous atrial depolarization. AV synchronous pacing. </li></ul><ul><li>VDD: A pacemaker that senses the atrium and ventricle and paces the ventricle (atrial synchronous, ventricular inhibited). </li></ul><ul><li>DDD: A pacemaker that senses and stimulates both atrium and ventricle. The stimulation rate, tracking rate and minimum rate are determined. </li></ul>SSI AAT VVT VAT VDD DDD
    15. 15. Pacemaker Modes <ul><li>SSIR: A pacemaker that senses and stimulates one chamber at a rate determined by a sensor. </li></ul><ul><li>AAIR: A pacemaker that senses and stimulates the atrium at a rate determined by a sensor. </li></ul><ul><li>VVIR: A pacemaker that senses and stimulates the ventricle at a rate determined by a sensor. </li></ul><ul><li>DDIR: A pacemaker that senses and stimulates both atrium and ventricle. The stimulation rate is governed by a maximum rate, the rate determined by a sensor and the minimum rate. </li></ul><ul><li>DDDR: A pacemaker that senses and stimulates both atrium and ventricle. The stimulation rate is governed by a maximum rate, the rate determined by a sensor and the minimum rate. </li></ul>SSIR AAIR VVIR DDIR DDDR
    16. 16. Single Chamber Pacing <ul><li>AAI </li></ul><ul><ul><li>Paces and senses only the atria </li></ul></ul><ul><ul><li>Must have proper AV conduction </li></ul></ul><ul><li>VVI </li></ul><ul><ul><li>Looses AV synchronicity </li></ul></ul><ul><ul><li>Used for temporary backup or with loss of AV conduction (AFib) </li></ul></ul>
    17. 17. Atrial Pacing
    18. 18. Ventricular Pacing
    19. 19. Loss of AV Synchrony <ul><li>Loss of atrial contribution </li></ul><ul><li>Decrease in LV preload </li></ul><ul><li>Decrease in stroke volume </li></ul><ul><li>Decrease in cardiac output </li></ul><ul><li>Decrease in cerebral perfusion </li></ul><ul><li>Decrease in coronary perfusion </li></ul><ul><li>Increase risk of pacemaker syndrome </li></ul>
    20. 20. Dual Chamber Pacing <ul><li>Maintains / Restores AV Synchrony </li></ul><ul><li>Optimizes heart function </li></ul><ul><li>Reduces pacemaker syndrome </li></ul><ul><li>Useful in CHF </li></ul><ul><li>Capable of mode switching </li></ul>
    21. 21. AV Pacing
    22. 22. Rate Response Pacing <ul><li>Uses sensor technology to provide rate modulation with exercise </li></ul><ul><li>AAIR </li></ul><ul><li>VVIR </li></ul><ul><li>DDDR </li></ul>
    23. 23. Rate Response Sensors <ul><li>Activity Sensors </li></ul><ul><ul><li>sensors that detect body movement. The more the patient’s body is moving (so the reasoning goes) the faster the heart rate should be. </li></ul></ul><ul><li>Breathing Sensors </li></ul><ul><ul><li>measures the patient’s rate of breathing. The faster the breathing, the faster the heart rate should be. </li></ul></ul>
    24. 24. Rate Response Pacing
    25. 25. Pacemaker Syndrome <ul><li>Often due to loss of AV Synchrony and/or delayed conduction time </li></ul><ul><li>Shortness of Breath </li></ul><ul><li>Fatigue </li></ul><ul><li>Cough </li></ul><ul><li>Orthopnea </li></ul><ul><li>Headache </li></ul><ul><li>Syncope </li></ul><ul><li>Vertigo </li></ul><ul><li>Choking Sensation </li></ul><ul><li>CHF, Pulmonary Edema </li></ul><ul><li>Dizziness </li></ul><ul><li>Apprehension </li></ul><ul><li>Pulsations in the Neck </li></ul><ul><li>Palpitations </li></ul><ul><li>Chest Pain </li></ul><ul><li>Near Syncope </li></ul><ul><li>Jaw Pain </li></ul><ul><li>Confusion </li></ul><ul><li>Altered Mental Status </li></ul>
    26. 26. Troubleshooting <ul><li>Twelve Leads are Better than One. </li></ul><ul><li>Choose leads that show the P wave and QRS morphology best. </li></ul><ul><li>Look for the pacer spikes. </li></ul>
    27. 27. Failure To Pace
    28. 28. Causes of Output Failure <ul><li>Lead Fracture </li></ul><ul><li>Lead Dislodgement </li></ul><ul><li>Lead Disconnect </li></ul><ul><li>Electromagnetic Interference </li></ul><ul><li>Battery Failure </li></ul><ul><li>Component Failure </li></ul><ul><li>Over sensing </li></ul>
    29. 29. Nursing Actions <ul><li>Assess and Treat Patient </li></ul><ul><li>Temporary Pacemaker </li></ul><ul><ul><li>Make Sure Unit Is Turned On </li></ul></ul><ul><ul><li>Check Battery and Connections </li></ul></ul><ul><ul><li>Check Rate, Increase Rate As Needed </li></ul></ul><ul><ul><li>Check mA, Increase Output As Needed </li></ul></ul><ul><ul><li>Decrease Sensitivity (toward asynchronous or 20mV) </li></ul></ul><ul><li>Prepare For Transcutaneous Pacing </li></ul><ul><li>Notify MD As Necessary </li></ul>
    30. 30. Failure To Capture
    31. 31. Failure To Capture
    32. 32. Causes of Loss of Capture <ul><li>Lead Dislodgement </li></ul><ul><li>Lead Insulation Defect </li></ul><ul><li>Battery Failure </li></ul><ul><li>Exit Block </li></ul><ul><li>Elevated Pacing Thresholds </li></ul><ul><li>Acute MI </li></ul><ul><li>Electrolyte Imbalance </li></ul><ul><li>Medications </li></ul><ul><li>Metabolic Disorders </li></ul><ul><li>Defibrillation </li></ul><ul><li>Long QT Syndrome </li></ul>
    33. 33. Loss of Capture <ul><li>Causes: </li></ul><ul><ul><li>Catheter Dislodgement </li></ul></ul><ul><ul><li>Catheter Fracture </li></ul></ul><ul><ul><li>Unstable Connection </li></ul></ul><ul><ul><li>Local Myocardial Necrosis/Fibrosis </li></ul></ul><ul><ul><li>Local Myocardial Inflammation </li></ul></ul>
    34. 34. Loss of Capture <ul><li>Causes: </li></ul><ul><ul><li>Drug Effects </li></ul></ul><ul><ul><li>Metabolic Effects </li></ul></ul><ul><ul><li>Cautery (DC Cardioversion, Ablation) </li></ul></ul><ul><ul><li>Lead Conductor or Insulation Failure </li></ul></ul><ul><ul><li>Generator Malfunction </li></ul></ul>
    35. 35. Nursing Actions <ul><li>Assess and Treat Patient </li></ul><ul><li>Temporary Pacemaker </li></ul><ul><ul><li>Make Sure Unit Is Turned On </li></ul></ul><ul><ul><li>Check Battery and Connections </li></ul></ul><ul><ul><li>Check mA, Increase Output As Needed </li></ul></ul><ul><ul><li>Check Rate, Increase Rate As Needed </li></ul></ul><ul><ul><li>Decrease Sensitivity (toward asynchronous or 20mV) </li></ul></ul><ul><li>Prepare For Transcutaneous Pacing </li></ul><ul><li>Notify MD As Necessary </li></ul>
    36. 36. Pacemaker Sensitivity <ul><li>Low Sensitivity </li></ul><ul><ul><li>Towards Asynchronous </li></ul></ul><ul><ul><li>Toward Higher mV (20mV) </li></ul></ul><ul><ul><li>Decreases pacemaker sensing ability </li></ul></ul><ul><li>High Sensitivity </li></ul><ul><ul><li>Maximal Sensitivity </li></ul></ul><ul><ul><li>Toward Lower mV (1mV) </li></ul></ul><ul><ul><li>Increases pacemaker sensing ability </li></ul></ul>
    37. 37. Failure To Sense
    38. 38. Failure To Sense
    39. 39. Nursing Actions <ul><li>Assess and Treat Patient </li></ul><ul><li>Temporary Pacemaker </li></ul><ul><ul><li>Make Sure Unit Is Turned On </li></ul></ul><ul><ul><li>Check Battery and Connections </li></ul></ul><ul><ul><li>Increase Sensitivity (toward synchronous or 1mV) </li></ul></ul><ul><ul><li>Check mA, Increase Output As Needed </li></ul></ul><ul><ul><li>Check Rate, Increase Rate As Needed </li></ul></ul><ul><li>Prepare For Transcutaneous Pacing </li></ul><ul><li>Notify MD As Necessary </li></ul>
    40. 40. Pacemaker Interference <ul><li>Electromagnetic Interference (EMI) </li></ul><ul><ul><li>Electromagnetic fields </li></ul></ul><ul><ul><li>Defibrillation </li></ul></ul><ul><ul><li>Electrocautery </li></ul></ul><ul><ul><li>Ablation </li></ul></ul><ul><ul><li>Lithrotripsy </li></ul></ul><ul><ul><li>Magnetic Resonance imaging (MRI) </li></ul></ul><ul><ul><li>High dose radiotherapy </li></ul></ul><ul><ul><li>Cellular telephones </li></ul></ul><ul><ul><li>TENS </li></ul></ul><ul><li>Twiddler’s Syndrome </li></ul>
    41. 41. Fusion Beats
    42. 42. Pacemaker Magnet <ul><li>A pacemaker magnet placed over a pacemaker generator typically eliminates sensing and returns the pacemaker to an asynchronous pacing mode (AOO, VOO or DOO). </li></ul><ul><li>When using a pacemaker magnet, the rhythm changes to a controlled paced rhythm. </li></ul><ul><li>Use caution when removing a pacemaker magnet because it can cause a reentry tachycardia. The last asynchronous beat is conducted through the AV node to the atrium. In this case, treat this dysrhythmia by reapplying the magnet. </li></ul>
    43. 43. Pacemaker Magnet Tracing
    44. 44. Transvenous Pacing <ul><li>Transvenous Pacing </li></ul><ul><ul><li>Start with new battery </li></ul></ul><ul><ul><li>Secure leads and connections </li></ul></ul><ul><ul><li>Set mA to 5 and adjust for capture </li></ul></ul><ul><ul><li>Keep mA 2-3 times the threshold </li></ul></ul>
    45. 45. Transvenous Threshold <ul><li>Transvenous Threshold </li></ul><ul><ul><li>Gradually decrease mA from 5 (to 0) until 1:1 capture is lost. Then increase mA until 1:1 capture is reestablished. </li></ul></ul><ul><ul><li>Set the mA 2-3 times the threshold. </li></ul></ul><ul><ul><li>Check threshold qd and prn, unless directed otherwise by physician. </li></ul></ul>
    46. 46. Transcutaneous Pacing <ul><li>Transcutaneous Pacing </li></ul><ul><ul><li>Keep pads off pacemaker/ICD devices </li></ul></ul><ul><ul><li>Set mA to 40 and adjust for capture </li></ul></ul><ul><ul><li>Remove paste from chest wall </li></ul></ul><ul><ul><li>Avoid arching </li></ul></ul><ul><ul><li>Keep mA 2 X threshold </li></ul></ul>
    47. 47. Transcutaneous Threshold <ul><li>Transcutaneous Threshold </li></ul><ul><ul><li>Gradually decrease mA from to 40 until 1:1 capture is lost. Then increase mA until 1:1 capture is reestablished. </li></ul></ul><ul><ul><li>Set the mA 2 times the threshold. </li></ul></ul><ul><ul><li>Check threshold qd and prn, unless directed otherwise by physician. </li></ul></ul>
    48. 48. Epicardial Pacing <ul><li>Epicardial Pacing </li></ul><ul><ul><li>Start with new battery </li></ul></ul><ul><ul><li>Secure leads and connections </li></ul></ul><ul><ul><li>Set mA to 3-5 and adjust for capture </li></ul></ul><ul><ul><li>Keep mA 3 X threshold </li></ul></ul>
    49. 49. Epicardial Threshold <ul><li>Epicardial Threshold </li></ul><ul><ul><li>Gradually decrease mA from to 5 until 1:1 capture is lost. Then increase mA until 1:1 capture is reestablished. </li></ul></ul><ul><ul><li>Set the mA 3 times the threshold. </li></ul></ul><ul><ul><li>Check threshold qd and prn, unless directed otherwise by physician. </li></ul></ul>
    50. 50. Pacemaker Sensitivity <ul><li>Low Sensitivity </li></ul><ul><ul><li>Towards Asynchronous </li></ul></ul><ul><ul><li>Toward Higher mV (20mV) </li></ul></ul><ul><ul><li>Decreases pacemaker sensing ability </li></ul></ul><ul><li>High Sensitivity </li></ul><ul><ul><li>Maximal Sensitivity </li></ul></ul><ul><ul><li>Toward Lower mV (1mV) </li></ul></ul><ul><ul><li>Increases pacemaker sensing ability </li></ul></ul>
    51. 51. Sensitivity Threshold <ul><li>Sensitivity Threshold </li></ul><ul><ul><li>Set rate just below patient’s intrinsic rate, the pacemaker should stop pacing and the sensor light should start flashing. </li></ul></ul><ul><ul><li>Gradually decrease sensitivity until the pacemaker begins to fire. This is the sensitivity threshold. </li></ul></ul><ul><ul><li>Set sensitivity to 2-3 times the sensitivity threshold. </li></ul></ul>
    52. 52. Other Pacemaker Settings <ul><li>High/Low Rate </li></ul><ul><ul><li>Sets the highest and lowest rates that the pacemaker can pace. </li></ul></ul><ul><li>AV Interval Control </li></ul><ul><ul><li>Set between 150-250 msec to preserve AV synchrony. </li></ul></ul><ul><li>Refractory Periods </li></ul><ul><ul><li>Sets a period of msec in which the pacemaker will not respond after a sensed or paced beat. </li></ul></ul>
    53. 53. Special Considerations <ul><li>Not necessary to disconnect temporary pacemaker during cardioversion or defibrillation </li></ul><ul><li>Changes in pacing threshold may occur with electrolyte imbalance, myocardial ischemia, anemia, CHF, hypoxia, or a change in drug therapy </li></ul><ul><li>  Pacing threshold increases over time </li></ul>
    54. 54. Nursing Management <ul><li>Continuous Cardiac Monitoring </li></ul><ul><ul><ul><ul><li>Watch for pacemaker complications </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Always evaluate cardiac tracings </li></ul></ul></ul></ul><ul><li>Electrical Safety Measures </li></ul><ul><ul><ul><ul><li>Use rubber gloves when handling external pacemaker components </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Regularly inspect all connections </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Replace batteries as needed ( have spares available) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Avoid EMI sources </li></ul></ul></ul></ul><ul><li>Monitor Thresholds </li></ul><ul><li>Monitor All Imbalances </li></ul><ul><ul><ul><li>Temperature, Acid-Base, Electrolytes </li></ul></ul></ul><ul><li>Monitor Medication Effects </li></ul><ul><li>Watch For Pacemaker Syndrome </li></ul>
    55. 55. Nursing Assessment <ul><li>Assess the Patient </li></ul><ul><ul><ul><ul><li>Vital Signs </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Cardiac Rhythm (always run strips) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Patient Complaints </li></ul></ul></ul></ul><ul><li>Assess the Pacemaker </li></ul><ul><ul><ul><ul><li>Maintain Electrical Safety </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Inspect and Secure Connections </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Assess the Effectiveness of the Pacemaker </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Check Thresholds </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Change Battery As Needed (keep spares available) </li></ul></ul></ul></ul>
    56. 56. Pacemaker Evaluation <ul><li>What is the rhythm? </li></ul><ul><li>Is the pacemaker functioning properly? </li></ul><ul><li>What is the immediate nursing action? </li></ul>
    57. 57. Pacer Rhythm Evaluation <ul><li>What is the pacing Mode? </li></ul><ul><li>What is the underlying rhythm? </li></ul><ul><li>Is the pacer firing appropriately? </li></ul><ul><li>Is the capture appropriate? </li></ul><ul><li>Is the sensing appropriate? </li></ul><ul><ul><ul><li>What is the low rate limit? </li></ul></ul></ul><ul><ul><ul><li>What is the high rate limit? </li></ul></ul></ul><ul><ul><ul><li>What is the AV delay? </li></ul></ul></ul>
    58. 58. Nursing Management <ul><li>Continuous Cardiac Monitoring </li></ul><ul><ul><ul><ul><li>Watch for pacemaker complications </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Always evaluate cardiac tracings </li></ul></ul></ul></ul><ul><li>Electrical Safety Measures </li></ul><ul><ul><ul><ul><li>Use rubber gloves when handling external pacemaker components </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Regularly inspect all connections </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Replace batteries as needed ( have spares available) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Avoid EMI sources </li></ul></ul></ul></ul><ul><li>Monitor Thresholds </li></ul><ul><li>Monitor All Imbalances </li></ul><ul><ul><ul><li>Temperature, Acid-Base, Electrolytes </li></ul></ul></ul><ul><li>Monitor Medication Effects </li></ul><ul><li>Watch For Pacemaker Syndrome </li></ul>
    59. 59. PRACTICE
    60. 60. AAI AAI: A pacemaker that stimulates and senses the atrium at one rate
    61. 61. VVI VVI: A pacemaker that stimulates and senses the ventricle at one rate
    62. 62. DDI DDI: A pacemaker that senses and stimulates both atrium and ventricle. The stimulation rate is fixed.
    63. 63. DDD
    64. 64. DDD or VVI?
    65. 65. DDDR
    66. 66. DDI
    67. 67. What’s the Mode?
    68. 68. What’s the Mode?
    69. 69. References <ul><li>Guidelines for Pacemakers and Defibrillators Updated. Journal Watch General Medicine 1998: 2-2. </li></ul><ul><li>Wood, D.A., Fox, K.F., Gibbs, S.R. (2001). Rapid cardiology--for chest pain, breathlessness and palpitations. QJ Med 94: 177-178.   </li></ul><ul><li>HAMMILL, S. C., HUBMAYR, R. D. (2000). The Rapidly Changing Management of Cardiac Arrhythmias. Am J Respir Crit Care Med 161: 1070-1073. </li></ul><ul><li>Bauersfeld, U., Nowak, B., Molinari, L., Malm, T., Kampmann, C., Schonbeck, M. H., Schuller, H. (1999). Low-energy epicardial pacing in children: the benefit of autocapture. Ann. Thorac. Surg. 68: 1380-1383. </li></ul><ul><li>KURBAAN, A S, SUTTON, R (1999). Pacing for vasovagal syncope. Heart 82: 649-650 </li></ul><ul><li>Braunwall, e. (1992) Heart Disease : a textbook of cardiovascular disease, 4 th edition, WB Saunders </li></ul><ul><li>American Radio Relay League, Inc., Technical Information Service, 225 Main St., Newington, CT 06111 (860) 594-0214. </li></ul><ul><li>Thelan, Lynne A., Davie, Joseph K., Urden, Linda D., Lough, Mary E. (1994) Critical Care Nursing: Diagnosis and Management. Second Edition. Pg 313-322. </li></ul><ul><li>Graver, K (1998) A Practical Guide to EKG Interpretation, 2 nd edition </li></ul><ul><li>On-line: http://www.emedicine.com/emerg/topic699.htm </li></ul>

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