Cardiac Electrophysiology & Ablation Electrophysiology study Cardiac Ablation Arrhythmias for ablation Supra-ventricular tachycardia Wolff-Parkinson White Atrial Flutter Atrial Fibrillation Atrial Tachycardia Ventricular Tachycardia Helen Eftekhari : Arrhythmia Nurse

THE HEART’S INTRINSIC CONDUCTION SYSTEM 1)Sino-Atrial node spreads depolarization wave across atria 2) Electrical Impulses collect at the atrio-ventricular node 3)Sends signals down conduction pathways depolarizing the ventricles.

Electrophysiology Study Study for diagnosis of tachycardia – induce tachy Recording of heart electrical activity Wires placed in right atrium heart to pace & sense (via RFV) Transeptal approach used to cross right atrium to left atrium Intracardiac electrogram (ICegram) records electrical activity at precise locations. 3-D mapping systems: computer-generated image of cardiac chambers

Catheter Ablation Destruction of Tissue Most Tachycardias depend on re-entry pathways (90%): can be focal Can be “cured” by destruction of tissue Energy source: Radiofrequency energy: cells destroyed by heating > 50C Cool-tip Cryoablation: specialised ablation catheter - liquid nitrous oxide released Complications: 1% permanent pacemaker, 1-2% cardiac tamponade, groin haematoma, <1% thromboembolic risk, Additional procedures: cardioversion, pericardiocentisis Post Ablation conduction block is checked.

Regular Narrow Complex Tachycardia (RNCT) SVT (supraventricular tachycardia) HR 150-250bpm Sudden Onset / Terminated by vasovagal manouvers or adenosine Atrio-ventricular re-entry tachycardia (AVRT) Atrio-ventricular node re-entry tachycardia (AVNRT)

Supra-Ventricular Tachycardia (SVT) Younger healthy people. Atrio-ventricular groove tough tissue Extra soft tissue (myocardial strands) = “Concealed” accessory pathway Extra electrical connection atria & ventricles Atrio-ventricular Re-entry tachycardia OR Dual AV node pathways (AVNRT) Slow pathway modification 70% middle aged women Success 90 – 95% : Post RFA VA block confirmed / no inducible tachycardia

Pre-Excitation

Wolf-Parkinson White Syndrome ECG : Revealed Pathway short PR interval (less 120ms) Slurring & slow rise of the QRS (delta wave) Widened QRS Complex (>0.12 milliseconds) Only ECG changes: WPW type ECG or pre-excitation Plus Palpitations = WPW syndrome ECG guides pathway location EPS diagnostic of exact position Manifest Accessory pathway: ability to conduct antegrade & retrograde Success 90% Post RFA success AV & VA block

WPWS & Atrial Fibrillation: Pre-Excited Atrial Fibrillation WPW accessory pathways conduct from atria to ventricles 20-30% of patients with accessory pathways prone to Atrial Fibrillation Not well understood why. Some pathways can rapidly conduct. Patients without a pathway who have atrial arrhythmias, the AV node acts as a brake. WPW in AF with rapidly conducting pathway = bypasses AV node = exceedingly rapid ventricular response. Diagnosis of Pre-excited Atrial Fibrillation is from ECG. Needs Urgent attention: high risk of degenerating into VF Fengler et al 2007, Gautam et el 2010)

Emergency Management Pre-excited AF this can increase conduction over pathway & high risk of VF Anti-Arrhythmic Drugs to treat Pre-Excited Atrial Fibrillation Class I: (1C class) Flecainide – usually the drug of choice (1A class) Procainamide Class III: amiodarone (to be used with caution) ibutilide Adenosine should be used with caution – although it acts on the AV node, adenosine has an extremely short half-life . Anti-Arrhythmic Drugs to Avoid in Pre-Excited Atrial Fibrillation (those which impede conduction via the AV node) Class II: Beta-Blockers Class IV Calcium Channel Blockers – Verapamil, Diltiazem Adenosine Class V Digoxin  ACC/AHA/ESC Guidelines 2003,Fengler et al 2007, Gautam et al 2010, Opie, L. Gersh, B. (2009) Drugs for the Heart. 7th Edition. Philadelphia, USA: Elsevier.  

Which Arrhythmia?

Atrial Flutter – CTI Ablation Macro-reentry circuit Commonest form: typical anti-clockwise atrial flutter (70%) Positive flutter waves V1; negative flutter waves in inferior leads Re-entry circuit in right atrium, anticlockwise dependent on tissue called cavo-tricuspid isthmus. CTI ablation.Anatomical procedure Around 90% success. Bidirectional block confirmed No transeptal approach stay on warfarin. INR’s above 2 for 3 weeks pre

Advice Post EPS & RFA /CTI Pre-Procedure stop anti-arrhythmics Successful procedure do not restart Aspirin / warfarin Heart Rhythm advice Groin Care Chest discomfort DVLA: 2 days – we recommend 1 week Flying 1 month Light activties within the 1st week- heavy activities 3-4 weeks

Which Arrhythmia?

Atrial Fibrillation – Pulmonary Vein Isolation Single source of electrical waves (pulmonary veins) 1-3 cm where myocardium fuses with pulmonary vein focus Paroxysmal Atrial Fibrillation Treatment for quality of life Transeptal approach 70% success in paroxysmal A.F. Success 50% if AF permanent. Complex add lines w/ substrate 1% risk stroke, 1% pulmonary stenosis, 1% phrenic nerve injury, 1% cardiac tamponade, 1% PPM

Ablate & Pace strategy Symptomatic atrial fibrillation Poor control w/ medical therapy No further options Implant permanent pacemaker Ablate AV node – cannot conduct fast atrial rates Poor percentage of biventricular pacing due to atrial fibrillation

Which Arrhythmia?

Atrial Tachycardia Lead V1, a negative or +/- P-wave was 100% specific for RA and a + or -/+ P-wave showed a sensitivity of 100% for an LA focus. Foci in atria drives tachycardia Difficult to ablate Needle in Haystack Complex mapping often required

Which Arrhythmia?

Different Arrhythmia?

Normal Heart Ventricular Tachycardia Right Ventricular Outflow Tract LBBB positive inferior leads Fascicular VT RBBB negative inferior leads

Ventricular Tachycardia Ventricular Tachycardia Ablation VT in normal hearts: Types of VT with good success (90%) for ablation: RVOT & fascicular. Very small numbers of patients with VT in structural heart disease are suitable for ablation. VT STIM: ventricular stimulation: EP study inducting ventricular tachycardia assess for ICD, VT ablation

Questions