Questions included for Critical Care Competency Day 2010 - 2011 Pacing Reference Questions included for Critical Care Competency Day 2010 - 2011

Pacemaker Medtronic 5388 Dual Chamber (DDD)

Temporary Pacing Review The following slides are designed to help you review some aspects of temporary pacing. Other resources available include pacing resource book in SICU medtronic website: temporary pacing powerpoints

Indications for Temporary Pacing

Placement of Epicardial Wires

Transvenous Pacing Insertion Sites Internal Jugular Vein External Jugular Vein Internal Jugular Subclavian Vein Subclavian Brachial Vein Femoral Femoral Vein

Transvenous Pacing Wire Bipolar lead system Transvenous wire is floated into the right ventricle The negative and positive electrodes are in contact with the heart

Single Chamber Temporary Pacing Pacer Settings: Pacing rate (heart rate) Output/stimulation threshold Sensitivity

Model 5388 Dual Chamber Temporary Pacemaker 1. Pace/Sense LEDs 2. Lock/Unlock Key 3. Lock Indicators 4. Rate Dial 5. Atrial Output Dial 6. Ventricular Output Dial 7. Menu Parameter Dial 8. Parameter Selection Key 9. Menu Selection Key 10. Pause Key 11. Power On Key 12. Power Off Key 13. Emergency/Asynchronous Pacing Key 14. Lower Screen 15. Ventricular Output Graphics 16. Atrial Output Graphics 17. Upper Screen 18. Rate Graphics 19. Setup Indicators 20. DDI Indicator 21. Low Battery Indicator 22. Setup Labels Single chamber pacing: AOO, VOO, AAI, VVI Dual chamber pacing: DDD, DDI, DVI, DOO Bipolar or unipolar configuration 9-volt alkaline or lithium battery power Three-dial operation to meet most patient needs Lock/Unlock key to prevent accidental parameter changes Emergency key for immediate high output asynchronous DOO pacing Menus for pacing parameter adjustments Rapid Atrial Pacing (RAP)

Lower Screen Menus Menu 1: Pacing Parameters Menu 2: Rate-Based Menus are for manual adjustment of pacing parameters, RAP, and pacing mode selection. Currently displayed parameters are based on the current pacing mode, rate, and output. Parameters not selectable are dimmed. MENU key: Activate lower screen and page through menus. SELECT key: Scroll through and highlight parameters. MENU PARAMETER dial: Adjust the value of the highlighted parameter. Lower screen: NBG pacing code appears in upper lefthand corner. *MANUAL appears in the upper right-hand corner to indicate that a parameter has been manually adjusted. Menu 3: Rapid Atrial Pacing Menu M: Dial-A-Mode

NBG Codes 1st Letter 2nd Letter 3rd Letter Chamber paced Chamber(s) Paced A = atrium V = ventricle D = dual (both atrium and ventricle) Chamber(s) Sensed A = atrium V = ventricle D = dual O = none Response to Sensing I = inhibit (Demand mode) T = triggered D = dual O = none (Asynch) Chamber paced Chamber sensed Action or response to a sensed event

Set Up Guide

Pacemaker EKG Strips Assessing Paced EKG Strips Identify intrinsic rhythm and clinical condition Identify pacer spikes Identify activity following pacer spikes Assess for Failure to capture Assess for Failure to sense EVERY PACER SPIKE SHOULD HAVE A P-WAVE OR QRS COMPLEX FOLLOWING IT.

Depolarization of cardiac muscle following an electrical stimulus Capture Depolarization of cardiac muscle following an electrical stimulus

Sensitivity The degree that the pacing system “sees” or senses signals, controlled by the sensitivity setting which is graduated in millivolts (mV) Sensitivity (mV) 5 (mV) 2.5 (mV) 1.25 (mV)

Sensitivity The lower the setting, the more sensitive the pacemaker is to intracardial signals

Normal Pacing Atrial Pacing Atrial pacing spikes followed by P waves

Normal Pacing Ventricular pacing Ventricular pacing spikes followed by wide, bizarre QRS complexes

Normal Pacing A-V Pacing Atrial & Ventricular pacing spikes followed by atrial & ventricular complexes

Troubleshooting Pacing Look for Failure to Fire (No Output from Pacer) Failure to Capture (pacer not followed by depolarization) Failure to Sense Undersensing: pacer not sensing all intrinsic activity so may misfire at inappropriate times Oversensing: pacer sensing artifact as well as intrinsic activity so may not fire when necessary

Failure to Fire: No Output Possible Causes Corrective Measures Battery depletion •Replace battery Pacemaker OFF •Verify pacemaker settings Faulty cable connections •Check cable connections Fractured/dislodged lead •Replace/reposition lead Oversensing •Verify/adjust sensitivity Possible Causes Corrective Measures Battery depletion •Replace battery Pacemaker OFF •Verify pacemaker settings Faulty cable connections •Check cable connections Fractured/dislodged lead •Replace/reposition lead Oversensing •Verify/adjust sensitivity Possible Causes Battery depletion Pacemaker off Faulty cable connection Dislodged/fractured lead Oversensing Corrective Measures Replace battery Verify pacemaker settings Check cable connections Reposition/replace lead Verify/adjust sensitivity

Failure to Fire Indicated by absence of pacer spikes where they should be Possible Causes: Solution: Low battery Replace battery Loose connections Check and secure connections Oversensing Increase mV to lower sensitivity Lead dislodged or Fractured Place skin wire or reposition transvenous wire

Factors that Affect Capture and Sensing

Failure to Capture Causes Danger - poor cardiac output Insufficient energy delivered by pacer Low pacemaker battery Dislodged, loose, fibrotic, or fractured electrode Electrolyte abnormalities Acidosis Hypoxemia Hypokalemia Danger - poor cardiac output

Failure to Capture Solutions Check connections Increase pacer output (↑mA) Change battery, cables, pacer Reverse polarity

Loss of Ventricular Capture Atrial/Ventricular Stimulation Thresholds Capture Loss of Ventricular Capture Capture-Depolarization of cardiac tissue after a pacing pulse. (The ECG shows a P-wave or QRS complex after the pacing pulse.) Loss of Capture-The ECG shows no heart response after the pacing pulse. Stimulation Threshold-Minimum output (mA) needed to consistently capture the heart. Safety Margin-Ensures consistent capture and accommodates a changing threshold. Provide a 2:1 safety margin by setting output to a value at least 2 times greater than the stimulation threshold value. Procedure: 1. Set RATE at least 10 ppm above patient’s intrinsic rate. 2. Decrease output: Slowly turn OUTPUT dial counterclockwise until ECG shows loss of capture. 3. Increase output: Slowly turn OUTPUT dial clockwise until ECG shows consistent capture. This value is the stimulation threshold. 4. Set output to a value at least 2 times greater than the stimulation threshold value. This provides at least a 2:1 safety margin. 5. Restore RATE to previous value. Caution: Monitor patient’s ECG and blood pressure during procedure.

Abnormal Pacing Atrial non-capture Atrial pacing spikes are not followed by P waves

Abnormal Pacing Ventricular non-capture Ventricular pacing spikes are not followed by QRS complexes

Capture Threshold testing Capture Stimulation threshold Definition: Minimum current necessary to capture & stimulate the heart Testing Set pacer rate 10 ppm faster than patient’s HR Starting at 0 mA, increase mA until 100% capture is obtained This is your pacing threshold Set mA 2-3x greater than the pacing threshold Example: Set output at 10-15 mA if 100% capture was at 5mA

Failure to Sense : Undersensing Causes Pacemaker not sensitive enough to detect patient’s intrinsic electrical activity (mVset too high) Asynchronous pacing Insufficient myocardial voltage Dislodged, loose, fibrotic, or fractured electrode Mechanical failure: wires, bridging cables, pacemaker Low battery Danger Potential (low) for paced ventricular beat to land on T wave and lead to Vtach

Undersensing Solutions Check all connections Make sure pacer is not set for asynchronous pacing Increase pacemaker sensitivity (↓mV) until pacer spikes move away from intrinsic beats Change battery

Undersensing Possible Causes Battery depletion Decreased QRS voltage Fusion beat Dislodged/fractured lead Ventricular ectopic activity Corrective Measures Change battery Increase sensitivity (decrease number) Reposition/replace lead Reposition patient

Abnormal Pacing Atrial undersensing Atrial pacing spikes occur irregardless of P waves Pacemaker is not “seeing” intrinsic activity

Abnormal Pacing Ventricular undersensing Ventricular pacing spikes occur regardless of QRS complexes Pacemaker is not “seeing” intrinsic activity

Failure to Sense Danger – potential for paced ventricular beat to land on T wave

Oversensing Inhibition of the pacemaker by events it should ignore such as: T waves Artifact

Oversensing Causes Pacemaker inhibited due to sensing of “P” waves & “QRS” complexes that do not exist Pacemaker too sensitive Possible wire fracture, loose contact Pacemaker failure Danger – asystole or heart rate too low to maintain adequate cardiac output If pacer “thinks” intrinsic heart rate is at or above set rate, then it won’t pace

Oversensing Solution Check connections Decrease pacemaker sensitivity (↑mV) Change cables, battery, pacemaker Reverse polarity Check electrolytes

Oversensing Possible Causes Myopotential inhibition EMI T-waves outside refractory period Dislodged/fractured lead Corrective Measures Eliminate interference Reduce sensitivity (increase number) Reposition/replace lead

One Last Thing to Consider: Fusion and Pseudofusion Beats Occurs when pacer fires just after intrinsic depolarization begins. Pacer spike will appear at middle to end of R wave. Beat will be intrinsic. This is also not a malfunctoning pacemaker. The pacemaker has fired too close to time of depolarization to be able to detect it. If this were undersensing the pacer spike would be at the end of QRS or later. Fusion Beat: When Intrinsic Depolarization Initiates at Same Instant as Pacer Fires: Beat is A combination Of a paced and Intrinsic beat This is NOT a problem with The pacemaker Intrinsic Beat Paced Beat Intrinsic Beat Paced Beat Fusion Beat Pseudofusion Beat Fusion Beat Pseudofusion Beat 34

Pacing Responsibilities Check all connections are proper Assess and troubleshoot pacing problems Failure to fire Failure to capture Under or over sensing Determine pacing threshold and set mA appropriately Document threshold and setting

Pacing Responsibilities Determine underlying rhythm and document This can be done when you are determining pacing threshold By turning down the mA to below the pacing threshold, the patient’s intrinsic rhythm will become apparent Document sensitivity settings Atrial is normally < 1 mV Ventricular is usually between 2-7 mV For patient attached to pacemaker but not actively pacing, thresholds still need to be checked and documented It is important to know that the pacemaker will work if the patient needs it Additionally for transvenous pacing Check and document position of pacing wire

Pacing Questions Look at each of the following pacing strips ?fire ?capture ?sensing properly if not, is it undersensing or oversensing ?what would you do if you saw this strip

Practice Strip #1

Practice Strip #2

Pacing Strip #3

Practice Strip #4

Practice Strip #5

Pacing Strip # 6

Pacing Strip # 7