PACEMAKERS AND ICDS INDICATIONS, FUNCTION AND TROUBLESHOOTING Tanja Sloan R.N., PA-C St. Vincent Healthcare Cardiac and Vascular Nursing Conference 2014
Disclosures I have no disclosures
Historical Perspective Electrical cardiac pacing for the management of brady-arrhythmias was first described in 1952 Permanent transvenous pacing devices were first implanted in the early 1960 s First ICD was implanted in 1980
Normal conduction system of the heart
Indications For Permanent Pacing Third degree AV block associated with: Symptomatic bradycardia Symptomatic bradycardia secondary to drugs required for dysrhythmia management Asystole > 3 seconds or escape rate < 40 After catheter ablation of the AV node Post-op AV block not expected to resolve Neuromuscular disease with AV block
Indications For Permanent Pacing Symptomatic bradycardia from second degree AV block Bifascicular or trifascicular block with intermittent third degree or type II second degree block Sinus node dysfunction with symptomatic bradycardia Recurrent syncope caused by carotid sinus stimulation
Indications For Permanent Pacing Post myocardial infarction with: Persistent second degree AV block with bilateral bundle branch block or third degree AV block Transient second or third degree AV block and bundle branch block Symptomatic, persistent second or third degree AV block
Miscellaneous Pacemaker Indications Hypertrophic obstructive cardiomyopathy Dilated cardiomyopathy Cardiac transplantation Termination and prevention of tachyarrhythmias Congenital heart disease in children and adolescents
Indications for Implantable Cardiac Defibrillator Placement Class I 1.Cardiac Arrest Due to VT or VF Not due to transient or reversible cause 2.Spontaneous sustained VT With structural heart disease 3.Syncope of undetermined origin with: Inducible sustained VT or VF that has clinical relevance and/or hemodynamic significance Class II 1.Sustained VT Normal or near-normal LVEF 2.Unexplained Syncope with: Significant LV dysfunction and NICM
Pacing types Temporary Permanent BiVentricular
Pacemaker Components Pulse Generator Electronic Circuitry Lead system ICD + High power
Pulse Generator Lithium-iodine cell is the current standard battery Advantages: Long life 6 to 10 years Output voltage decreases gradually with time making sudden battery failure unlikely
Lead Systems Endocardial leads which are inserted using a subclavian vein approach Actively fixed to the endocardium using screws or tines Unipolar or bipolar leads
Pacemaker Functions Stimulate cardiac depolarization Sense intrinsic cardiac function Respond to increased metabolic demand by providing rate responsive pacing Provide diagnostic information stored by the pacemaker
ICD Therapies Brady pacing Antitachycardia pacing Cardioversion (1 to 40J) Defibrillation (up to 40J)
ICD Therapy ICD Therapy Low Power (Pacing Therapies) Anti-tachycardia Pacing (ATP) Bradyarrhythmia Pacing High Power (Shock Therapies) Cardioversion Defibrillation
Pacing Function: Asynchronous/Fixed Rate Does not synchronize with intrinsic HR Used safely in pts with no intrinsic ventricular activity If pt has ventricular activity, it may compete with pt s own conduction system VT may result (R-on-T phenomenon)
Pacing Function: Synchronous/Demand Contains two circuits * One forms impulses * One acts as a sensor When activated by an R wave, sensing circuit either triggers or inhibits the pacing circuit Called Triggered or Inhibited pacers Most frequently used pacer Eliminates competition Energy sparing
Pacing Function Atrial pacing: Stimulation of right atrium produces spike on EKG preceding P wave
Pacing Function Ventricle pacing : Stimulation of RT or LT ventricle produce a spic on ECG preceding QRS complex
Pacing Function AV pacing: Direct stimulation of right atrium and either ventricles to mimic normal heart conduction
Sensing Function Sensing: Ability of the pacemaker to see intrinsic cardiac activity when it occurs. Two types: Demand: pacing stimulation delivered only if the heart rate falls below the preset limit. Fixed: no ability to sense. constantly delivers the preset stimulus at preset rate. Triggered: delivers stimuli in response to (sensing) cardiac event.
Capture Function Capture: Ability of the pacemaker to generate a response from the heart (contraction) after electrical stimulation.
Capture Function Electrical capture: Indicated by P or QRS following and corresponding to a pacemaker spike. Mechanical capture: Palpable pulse corresponding to the electrical event.
Troubleshooting Define the problem Identify the cause of the problem Correct the problem Verify the solution
Pacemaker complications Pacemaker complications are divided into: Implant related complications Lead related complications Pacemaker malfunction
Implanted related complications 1. Procedure related/acute Subclavian puncture Traumatic pneumothorax Hemothorax, air embolism AV fistula Thoracic duct injury Brachial plexus injury
Implanted related 2. Hematoma formation at pulse generator 3. Thrombus formation/embolism/av thrombus Asymptomatic due to collaterals 4. Lead perforation/cardiac tamponade rising threshold, diaphragmatic stimulation, friction rub, hypotension 5. SVT/VT during implantation
Pacemaker Infections Pacemaker insertion is a surgical procedure: 1% risk for bacteremia 2% risk for wound or pocket infection Usually occur soon after pacer insertion Presence of a foreign body complicates management Most common S. Aureus/Epidermis Lead vegetations Local inflammation, fever, +BC
Lead related complications 1. Lead dislodgement A>V 2. Lead fracture Usually occurs adjacent to PM near venous site If fracture of bipolar lead occurs, may be possible to reprogram to unipolor configuration 3. Loss of integrity of insulation Manufacturing defects/wear & tear Crush injury
Lead related complications 4. Exit block Abnormality at myocardial-electrode interface 5. Diaphragmatic or pectoral muscle pacing Dislodgement, insulation defects, common with unipolar leads
Pacemaker Failure A. Early: electrode displacement/breakage B. Failure > 6 months Premature battery depletion Faulty pulse generator
Pacemaker Malfunction Generally Be Assigned To Five Categories: Undersensing Oversensing Noncapture No output Pseudomalfunction
Undersensing may be caused by: Inappropriately programmed sensitivity Lead dislodgment Lead failure Insulation break; conductor fracture Lead maturation Change in the native signal
Undersensing Pacer fails to detect an intrinsic rhythm Paces unnecessarily Patient may feel extra beats If an unneeded pacer spike falls in the latter portion of T wave, dangerous tachyarrhythmias or V fib may occur TX: Increase sensitivity of pacer
Undersensing An intrinsic depolarization that is present, yet not seen or sensed by the pacemaker
Oversensing may be caused by: Lead failure Poor connection at connector block Exposure to interference
Oversensing Pacer interprets noncardiac electrical signals as originating in the heart Detects extraneous signals such as those produced by electrical equipment or the activity of skeletal muscles (tensing, flexing of chest muscles, EMI) Inhibits itself from pacing as it would a true heart beat
Oversensing On ECG: pauses longer than the normal pacing interval are present Often, electrical artifact is seen Deprived of pacing, the patient suffers CO, feels dizzy/light-headed Most often due to sensitivity being programmed too high TX: Reduce sensitivity
Oversensing The sensing of an inappropriate signal Can be physiologic or nonphysiologic
Noncapture Pacer s electrical stimulus (pacing) fails to depolarize (capture) the heart There is no failure to pace Pacing is simply unsuccessful at stimulating a contraction ECG shows pacer spikes but no cardiac response CO occurs TX: threshold/output strength or duration
Noncapture No evidence of depolarization after pacing artifact
Noncapture
Noncapture can be caused by: Lead dislodgment Low output Lead maturation Poor connection at connector block Lead failure
Less common causes of noncapture Twiddler s syndrome Electrolyte abnormalities Myocardial infarction Drug therapy Battery depletion
Output failure Output failure occurs when a paced stimulus is not generated in a situation where expected. Results in decreased or absent pacemaker function. Very rare, usually a malfunctioning device.
Output failure
Pseudomalfunction Pseudomalfunctions are defined as: Unusual Unexpected Eccentric ECG findings that appear to result from pacemaker malfunction but that represent normal pacemaker function
Pseudomalfunctions May Be Classified Under The Following Categories: Rate AV interval/refractory periods Mode
Rate Changes May Occur Due To Normal Device Operation: Magnet operation Timing variations A-A versus V-V timing Upper rate behavior Pseudo-Wenckebach; 2:1 block Electrical reset Battery depletion PMT intervention Rate response
Magnet operation Magnet application causes asynchronous pacing at a designated magnet rate
Pacemaker Mediated Tachycardia (PMT) A rapid paced rhythm that can occur with atrial tracking pacemakers
PMT Retrograde conduction Tracking fast atrial rates (physiologic or nonphysiologic)
Retrograde Conduction May Be Caused By: Loss of A-V synchrony due to: Loss of sensing/capture Myopotential sensing Premature ventricular contraction (PVC) Magnet application
Pacemaker troubleshooting
Common problems with ICDs Common: Recalled device issues of varying severity SVTs causing inappropriate shocks Less common: Oversensing (electromagnetic interference, myopotentials) causing inappropriate shocks Lead failure causing inappropriate shocks, pacing problems or sensing problems
ICD with repeated shocks Place magnet over ICD Place external defibrillator pads and telemetry Initiate ACLS or critical care management as appropriate OK to do CPR or external defibrillation before magnet is placed
Case Study 1 67 year old male presents to the emergency room 12 hours after insertion of a pacemaker complaining of left sided chest pain and shortness of breath PR96, RR 33, BP 125/85, Oxygen saturation 88% RA CXR as shown
Pneumothorax Occurs during cannulation of the subclavian vien Incidence -?? Cardiologist dependent Treatment: Asymptomatic or small observation Symptomatic or large tube thoracostomy
Case Study 2 72 year old male presents to the emergency room after a fall, tripped over a bath mat, no LOC Shortened and rotated left leg Past history pacemaker, hypertension Nurse does an routine pre-op CXR and EKG
Septal Perforation Usually identified at the time of pacer insertion but leads can displace after insertion Can occur with transvenous pacer insertion Keys diagnosis are a RBBB pattern on EKG and a pacer lead displaced to the apex of the heart on CXR
Septal Perforation Management: Pacer wire has to be removed but not emergently Small VSD which heals spontaneously
Case Study 83 year old female underwent PPM implantation several hours ago Patient is doing well, VS are stable