Heart Blocks and Pacing PDN Julie Allen SN Solon Avanzado The Queen Elizabeth Hospital King’s Lynn

PQRST in Normal Sinus Rhythm Explanation of NSR, ask group to come up with what is happening at each point – useful to draw diagram with conduction system

Conduction system

FIRST Look at the patient! Convey the importance of the patients condition and troubleshooting ie not assuming asystole when leads are off!

Arrhythmias – at a glance! Patient? – poorly or well Rate? – Too fast or too slow Complexes? – Narrow or Wide Treatments? Drugs or electricity Simplified assessment process

Heart Blocks Block in normal conduction Could be at any part of the conduction system Ranging in severity Transient or permanent Can deteriorate May require pacing Introduction to heart blocks

1st Degree Block Ask the students what they see. Explain characteristics, possible causes, effects on the patient, appropriate management

2nd Degree Block Mobitz Type 1: Wenckebach Ask the students what they see. Explain characteristics, possible causes, effects on the patient, appropriate management

2nd Degree Block Mobitz Type II

Complete Heart Block Ask the students what they see. Explain characteristics, possible causes, effects on the patient, appropriate management

Pacing Temporary – Permanent – Implanted device Transcutaneous (Emergency use with external pacing/defib unit, precordial thump!!!!!) Transvenous (Emergency use with external pacemaker) Permanent – Implanted device

Indications for Temporary Bradycardia with unstable haemodynamics unresponsive to Atropine. Bradycardia with symptomatic escape rhythms unresponsive to medication. PEA - overdose, electrolyte abnormalities, acidosis Over ride pacing – refractory tachycardias (failed cardioversion or medication) Inferior MI with Heart Block

Contraindications to temporary pacing Severe hypothermia Prolonged bradyasystolic arrest

Types of pacing box Single Chamber Dual Chamber

Indications for permanent • Symptomatic CHB CHB that does not recover following: - MI after 2 weeks - Valve replacement after 1 week - CABG after 2 weeks Bifascicular block, BBB or CHB post anterior infarct Symptomatic sinus arrest or AV block not related to drugs

Permanent Pacing Single/Dual chamber Pacing and defibrillate Magnets and MRI scanners

Atrial pacing Indications : • Sinus bradycardia • Supression of ventricular ectopics • Slow junctional rhythms • Overdrive pacing of supra-ventricular tachycardias NB – atrial pacing is ineffective in atrial fibrillation and fluter

Atrio-ventricular pacing (Sequential pacing) Indications : • Complete block • Second degree block to achieve 1:1 conduction • First degree block if PR interval too long AV pacing is always preferable to single chamber pacing.

Ventricular pacing Indications : • Slow ventricular response to atrial fibrillation/flutter • Failure of atrial pacing to maintain heart rate NB – ventricular pacing is the least effective mode for optimising haemodynamics.

Pacing Modes Fixed rate: Pacing Mode stimulates the heart at a pre-set interval Does not respond to intrinsic heart activity !!Fixed ventricular pacing can trigger VT/VF!!

Pacing Modes Demand: Pacemaker initiates an impulse only when a pre-set R-R interval has elapsed without spontaneous cardiac activity The escape interval is determined by the rate the pacemaker is set The pacemaker is inhibited by intrinsic cardiac activity

Complications Permanent Temporary Pneumothorax Pericardial effusion Infection – endocarditis Hematoma Wire displacement Avoid placing defibrillator pads directly over permanent pacing devices Transvenous – All the same as Permanent with increased risk of wire displacement Transcutaneous – Poor contact resulting in non-pacing Skin burns (abrasions, prolonged usage without changing pads regularly)

Other issues with permanent MRI scanning – myth that unable to go in MRI Travel – Pacemaker cards are carried for travelling through security. Driving – 1 week after implantation for ordinary (Group1) 6 weeks for vocational (Group 2) Batteries - 7-10 years depending upon usage. MRI 1.5% of 438pts & 500 scans resulted in heart device to reverting to default settings . Circulation 2006; 114 (12):1277-1284

Analysis of Pacing Problem Need to obtain rhythm strip or 12 lead ECG Establish pacemaker settings (if possible) If there are pacing spikes with no corresponding P-QRS = pacing/capture problem If there are no pacing spikes where you would expect them = sensing problem

Atrial pacing, Ventricular pacing, failure to capture, failure to sense

Nursing Care Transcutaneous Transvenous Explain to patient Skin prep – trim hair, dry skin Good skin contact – avoid electrodes & transdermal patches Avoid carotid pulse check use femoral Pain relief & sedation Monitor & record Hr rate & rhythm Monitor & record pacing (rate, current output, mode) Monitor & record Hr, B/P & rhythm to assess response Observe sensing of intrinsic beats & appropriate device pacing Secure wire and device – extreme care with confused patients Immobility - bedrest