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ARRHYTHMIAS. TACHYCARDIA >100/min BRADYCARDIA <50/min CARDIAC ARREST Electrical activity Chaotic VF Absent asystole. Action potential. 0. -60. Propagating action potential. 0. -60. Propagating action potential. 0. -60. Propagating action potential. 0. -60.
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ARRHYTHMIAS • TACHYCARDIA >100/min • BRADYCARDIA <50/min • CARDIAC ARREST Electrical activity • Chaotic VF • Absent asystole
Action potential 0 -60
TREATMENT STRATEGY • PROLONG ACTION POTENTIAL • MODIFY CONDUCTION • STABILISE AUTOMATICITY • INTERRUPT REENTRY • PHARMACOLOGICAL • PHYSICAL • ELECTRICAL STIMULATION • ATP/SHOCK TACHY • PACE BRADY
DEPOL Inward REPOL outward
TREATMENT STRATEGY • PROLONG ACTION POTENTIAL • MODIFY CONDUCTION • STABILISE AUTOMATICITY • INTERRUPT REENTRY • PHARMACOLOGICAL • PHYSICAL • ELECTRICAL STIMULATION • ATP/SHOCK TACHY • PACE BRADY
DEPOL Inward REPOL outward
DEPOL Inward REPOL outward
AUTOMATICITY Physiological: Sinus node Pathological: Reduction/depolarisation of resting membrane potential (e.g. Ischaemia)
TREATMENT STRATEGY • PROLONG ACTION POTENTIAL • MODIFY CONDUCTION • STABILISE AUTOMATICITY • INTERRUPT REENTRY • PHARMACOLOGICAL • PHYSICAL • ELECTRICAL STIMULATION • ATP/SHOCK TACHY • PACE BRADY
Tachyarrhythmias • Antiarrhythmic drugs • Vaughan-Williams Classification • Drugs divided according to EP effects on cells • All are negatively inotropic • Can also be pro-arrhythmic
Tachyarrhythmias • Class I • Impede Na transport across cell membrane • Ia increase AP duration eg quinidine, disopyramide, procainamide • Ib shorten AP duration eg lignocaine, mexilitene, propafenone • Ic little effect on AP eg flecainide
Tachyarrhythmias • Class II • Interfere with effects of SNS on the heart eg beta blockers • Class III • Prolong AP duration but do not effect initial Na dependent phase eg sotalol, amiodarone • Class IV • Antagonise Ca transport across cell membrane • SA and AV node particularly susceptible eg verapamil, diltiazem
TREATMENT STRATEGY • PROLONG ACTION POTENTIAL • MODIFY CONDUCTION • STABILISE AUTOMATICITY • INTERRUPT REENTRY • PHARMACOLOGICAL • PHYSICAL • ELECTRICAL STIMULATION • ATP/SHOCK TACHY • PACE BRADY
AV Nodal block • [Class II • Interfere with effects of SNS on the heart eg beta blockers] • Class III • Prolong AP duration but do not effect initial Na dependent phase eg sotalol, amiodarone • Class IV • Antagonise Ca transport across cell membrane • SA and AV node particularly susceptible eg verapamil, diltiazem • Adenosine • Specific AV nodal block
TREATMENT STRATEGY • STABILISE AUTOMATICITY • PROLONG ACTION POTENTIAL • SLOW CONDUCTION • INTERRUPT REENTRY • PHARMACOLOGICAL • PHYSICAL • ELECTRICAL STIMULATION • ATP/SHOCK TACHY • PACE BRADY
RFA: success rates • AVJ 98% • AVNRT 97% • AP 93% (L 95%, R 89%) • AFl 95% • Infarct VT 60-90%, long term 50% • Idiopathic VT 90% • Focal AF 60%
RFA: treatment of choice • AVJ 98% • AVNRT 97% • AP 93% (L 95%, R 89%) • AFl 95% • Idiopathic VT 90% ______________________________ • Infarct VT 60-90%, long term 50% • Focal AF 60%
Atrial Flutter: RFA vs AA drugsJACC2000;35:1898 prospective, randomised – 61 pts • SR at 21 months: 36%AAD vs 80% RFA • Rehospitalised: 63% AAD vs 22% RFA • AF: 53% AAD vs 29% RFA • QOL: no change AAD improvement RFA
TREATMENT STRATEGY • PROLONG ACTION POTENTIAL • MODIFY CONDUCTION • STABILISE AUTOMATICITY • INTERRUPT REENTRY • PHARMACOLOGICAL • PHYSICAL • ELECTRICAL STIMULATION • ATP/SHOCK TACHY • PACE BRADY
Concepts of AF: 1900-2000 MULTIPLE WAVELETS Ines, Garrey MOTHER WAVE Lewis HYPEREXCITABILITY Engelmann, Winterberg