ECG interpretation Amarpal Bains

ECG Leads Derived leads; I, II, III Limb leads; aVR, aVL, aVF Precordial leads; V1, V2, V3, V4, V5, V6

Normal Sinus Rhythm Regular, 60-100, P-QRS-T PR interval 0.12-0.2s QRS <0.12s No ST changes

ECG checklist Patient Identity Rate and Rhythm Axis P waves PR interval QRS morphology/duration ST morphology

Torsades de Pointes Distinctive polymorphic VT where QRS amplitude varies and the complexes oscillate around the baseline because of >QTc Recurrent syncope/dizziness/palpitations, sudden cardiac death Congenital, post MI, electrolyte disturbances, DRUGS Resuscitation, Defibrillation, IV Magnesium, IV Isoprenaline, treat the cause

Drugs accepted to increase risk of >QTc/TdP; Haloperidol, Chlorpromazine, Methadone Drugs which possibly increase risk of >QTc/TdP; Risperidone, Quetiapine, Lithium, Clozapine, Escitalopram, Venlafaxine Inhibit cardiac delayed potassium rectifier channel (IKr) - extends ventricular repolarisation - >QTc

Things to consider Detailed cardiac FH/PMH Screen for electrolyte/metabolic disturbances (U&Es, Mg2+, Ca2+, TFTs) ECG (QTc >450ms/>470ms) Age >65/Female are risk factors

References Antipsychotic drugs: A review with a focus on QT prolongation. Journal of Pharmacy and Alternative Medicine ISSN 2222-5668 (Paper) ISSN 2222-4807 (Online)Vol. 2, No. 4, 2013 Drug-induced Long QT Syndrome. Pharmacol Rev. 2010 Dec; 62(4): 760–781. Torsades de Pointes. Professional references, patient.co.uk Drug-induced QT prolongation and Torsades de Pointes - the facts. Medsafe 31(4): 27-29