Cardiac side effects Flashcards
Heart rate for which QTc estimate the QT interval
60 bpm
Normal QTc in women
470ms
Normal QTc in men
440ms
QTc associated with an increased risk of torsades de pointes
> 500ms
Type of arrhythmia seen in torsade de pointes
Polymorphic ventricular tachycardia
Type of ventricular arrhythmia which is often self-terminating
Torsade de pointes
Symptoms seen in torsade de pointes
Often asymptomatic
Syncope
Cardiac death if degenerates into VF
Formula most often used to calculate QTc
Bazett’s formula
Physiological causes of prolonged QTc
Extreme physical exertion Stress Extremes of age Female sex Bradycardia
Metabolic causes of prolonged QTc
Hypokalaemia
Hypomagnesaemia
Hypocalcaemia
Issues with using Bazett’s formula to measure QTc
Over-corrects at HR >100bpm
Under-corrects at HR <60bpm
Medical causes of prolonged QTc
Hypothermia MI Anorexia nervosa Raised ICP Congenital long QT syndrome Myocarditis LVH
Antipsychotic with high impact on QTc
Pimozide
Antipsychotics with moderate effect on QTc
Haloperidol Quetiapine Chlorpromazine Ziprasidone Amisulpride
Antipsychotics with low effect on QTc
Clozapine Olanzapine Risperidone Aripiprazole Palperidone
Antipsychotic with no effect on QTc
Lurasidone
SSRI which causes prolonged QTc
Citalopram
Non-psychotropic medications which cause prolonged QTc
Ampicillin Erythromycin Clarithromycin Amiodarone Sotalol Chloroquine Quinine Methadone Tamoxifen Amantadine
Leads the QTc should be measured from
II
V5
V6
Part of the ECG the QT measures
Beginning of the QRS complex to the end of the T wave
Effect of SSRIs and mirtazapine on mortality post-MI
Neutral or positive
Least cardiotoxic TCA
Lofepramine
Antidepressants known to cause QTc prolongation at therapeutic doses
Trazodone
Citalopram
Antipsychotic with highest risk of prolonged QTc which has now been discontinued
Thioridazine
Medication used in addiction treatment associated with prolonged QTc
Methadone
Effect of meclobamide on QTc
No effect at therapeutic doses
Prolongation in overdose
Size of QTc effect of citalopram
Moderate
Cardiac side effects associated with lithium therapy
PR prolongation T wave flattening Sinus node dysfunction Higher variation in QT (higher QT dispersion ratio) Unmasking of Brugada syndrome
Cardiac side effects often associated with TCA treatment even at therapeutic levels
Prolonged QTc
Flattened T wave
Depressed ST segment
Tachycardia
