Pacemaker for beginners

1. Pacemaker for beginners KITA yosuke Iizuka Hospital

2. Objectives • Review basic pacemaker terminology and function • Discuss diagnosis and management of pacemaker emergencies

3. Historical Perspective • Electrical cardiac pacing for the management of brady-arrhythmias was first described in 1952 • Permanent transvenous pacing devices were first introduced in the early 1960’s

4. Pacemaker Components • Pulse Generator • Electronic Circuitry • Lead system

5. Pulse Generator • Lithium-iodine cell is the current standard battery • Advantages: • Long life – 4 to 10 years • Output voltage decreases gradually with time making sudden battery failure unlikely

6. Electronic Circuitry • Determines the function of the pacemaker itself • Utilizes a standard nomenclature for describing pacemakers

7. Pacemaker Nomenclature

8. 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

11. Electrocardiogram During Cardiac Pacing • Pacemaker has two main functions: • Sense intrinsic cardiac electrical activity • Electrically stimulate the heart • VVI- senses intrinsic cardiac activity in the ventricle and when a preset interval of time with no ventricular activity occurs it depolarizes the right ventricle causing ventricular contraction

12. Pacer spike

13. Electrocardiogram • Dual chamber pacer is more complicated because the pacer has the ability to both sense and pace either the atrium or the ventricle • Possible to have only atrial, only ventricular or both atrial and ventricular pacing • DDD pacer is a common example of this

14. Atrial Spike Ventricular Spike

15. Ventricular Pacing AV Pacing

16. Magnet Placement • The EKG technician should perform a 12 lead cardiogram and then a rhythm strip with a magnet over the pacer • Often a very poorly understood concept by the non-cardiologist • Does not inactivate the pacer as is commonly believed • Activate a lead switch present in the pacemaker which converts the pacer to a asynchronous or fixed-rate pacing mode • Inhibits the sensing function of a pacemaker

18. Class I 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

19. Indications • 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

20. Indications • Post myocardial infarction with any of: • 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

21. 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

22. Infection • Cellulitis or pocket infection: • Tenderness and redness over the pacemaker itself • Avoid performing a needle aspiration – damage the pacer • Bacteremia: Staphylococcus • aureus and Staphylococcus epi 60-70% of the time • Empiric antibiotics should include vancomycin pending culture

23. Infection • Consult the pacemaker physician • Draw blood cultures • Give appropriate antibiotics • Frequently the pacer and lead system need to be removed

24. Case 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

26. Pneumothorax • Occurs during cannulation of the subclavian vien • Incidence - ?? Cardiologist dependent • Treatment: • Asymptomatic or small – observation • Symptomatic or large – tube thoracostomy • Notify the pacemaker physician

27. Case 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

30. 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

31. Septal Perforation • Management: • Notify the pacer service • Pacer wire has to be removed but not emergently • Small VSD which heals spontaneously

32. Conclusions • Pacemakers are becoming more common everyday • We need to understand basic pacing terminology and modes to treat patients effectively. • Most pacer malfunctions are due to failure to sense, failure to capture, over-sensing, or in-appropriate rate • Standard ACLS protocols apply to all unstable patients with pacemakers.