2. Torsade de pointes or torsades is a French
term that literally means "twisting of the
points" is a ventricular tachycardia associated
with a long QT time on the resting ECG.
During Torsade de pointes the ventricles
depolarize in a circular fashion resulting in
QRS complexes with a continuously turning
heart axis around the baseline (hence the
name Torsade de Pointes).
It was first described by Dessertenne in 1966 .
17. Drugs Withdrawn for TdP
Drug Class
Terfenadine Antihistamine
Sertindole Antipsychotic
Astemizole Antihistamine
Grepafloxacin Antibiotic
Cisapride GI Prokinetic
18. CLINICAL FEATURES
Symtoms : syncope
palpitations
sudden death
ECG signs:
Long QT interval
Wide QRS
Continuously changing
QRS morphology
19. Diagnosis
First measure the QT interval
Secondly, correct it for the heart rate, if heart
rate is above 60.
Determine if it is greater than 0.5 seconds (500
msec) in duration.
Lastly, compare QTc to previous QTc’s to
determine if it is lengthening.
QTc for man:440ms and females:460ms.
20. QT Interval
• Measure from
beginning of q wave
to where the t wave
returns to baseline.
• “Rule of thumb” is it
Should be less than
50% of R-R interval.
•If =/> 500 msec 0.50
seconds) or > 50% of
R-R interval: risk for
Torsades de Pointes!
24. LONG TERM MANAGEMENT:
Beta blockers: Propranolol
Esmolol,Nadolol
Limitations:SCD can occur
Long term compliance
S/E:
IMPLANTABLE CARDIOVERTER
DEFIBRILLATOR:
Indications: Patients with VT,VF,aborted
cardiac arrest.
used with beta blockers.
25. Management of congenital long QT
syndrome:
Beta blockers:
ICDs:
Prevention of drug induced Tdps:
26. RECENT ADVANCES:
Genetic testing for carriers of long QT syndrome:
FAMILION LQTS TEST:
USES:
NOVELTHERAPY: Sodium channel blockers
CCBs
Atropine
Protien kinase inhibitors
Alpha blockers
Potassium chanl.openers
27. Drug Induced QT Prolongation
Preclinical Screeing
In vitro APD effects
Isolated myocytes
(dog,rabbit,g. pig)
Purkinje fibers (dog,rabbit)
Papillary muscle (guinea pig)
In vivo models
Conscious rabbit
Concious Hypokalemic
dogs
Canine models with