Download Torsades de pointes( TdP )

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Torsades de pointes
2012. 11. 8
순환기내과
R3 오치혁 / prof. 김진배
1. Introduction
• Torsades de pointes( TdP )
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“Twisting of the spikes“ : French term
First described by Dessertenne in 1966
Rare variety of ventricular tachycardia
A polymorphic ventricular tachycardia
with twisting of the QRS complex around the isoelectric baseline
usually terminates spontaneously
Fall in arterial blood pressure → syncope
Kyunghee Cardiovascular center
Division of cardiology
2
2. Characteristics
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Rotation of the heart's electrical axis by at least 180°
Prolonged QT interval (LQTS)
Preceded by long and short RR-intervals
Triggered by an early premature ventricular contraction
(R-on-T PVC)
Kyunghee Cardiovascular center
Division of cardiology
3
3. Epidemiology of Torsades
• Prevalence : unknown
• In USA, 300,000 sudden cardiac death per year
– Torsades probably accounts for fewer than 5%
• The white > the black : prolonged QTc interval
– lower susceptibility to acquired torsade in black persion
• In women > in men : 2~3 times
– Women have longer QT intervals
• Wide age range, from newborns to the very elderly
– The highest frequency is in patients aged 35-50 years
Kyunghee Cardiovascular center
Division of cardiology
Circulation. Jul 1982;66(1):218-25
Pacing Clin Electrophysiol. Oct 2006;29(10):1130-59
J Am Coll Cardiol. Jan 1997;29(1):93-9
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4. Risk factors
• Congenital long QT syndrome
• Female gender
• Acquired long QT syndrome
– (medications and electrolyte disorders such as hypoK and hypoMg)
• Bradycardia
• Baseline electrocardiographic abnormalities
• Renal or liver failure
Kyunghee Cardiovascular center
Division of cardiology
5
5. Causes
• This life-threatening arrhythmia
may be caused by factors that prolong the QT interval.
• Electrolyte
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Low Magnesium
Low Potassium
Low Calcium
• General condition
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Diarrhea, malnourished individuals, chronic alcoholics
• Myocardial ischemia
• Bradycardia, complete atrioventricular (AV) block
• Hereditary
– 1/3 asymptomatic, Suspect if hx. Fainting
– Triggers
• emotional excitement, exercise, being startled, anger, test-taking, stress
Kyunghee Cardiovascular center
Division of cardiology
6
5. Causes
Kyunghee Cardiovascular center
Division of cardiology
7
6. Diagnosis of Torsades
• Failure to identify
– very short runs of torsade
↔ the typical twisting of the QRS complexes around the isoelectric line
– Early events usually are short-lived
– In the case of a single-lead recording
• So!!!!
– any patient with pause-dependent ventricular tachycardia
– Ventricular Bigeminy in a patient with long QT interval
– SUSPICION !!!!
Kyunghee Cardiovascular center
Division of cardiology
8
7. Treatment of Torsade
• DC cardioversion (?)
• Predisposing factor
– Any offending agent
– hypokalemia, hypomagnesemia, and bradycardia
• Magnesium
• Potassium & Calcium supply
• Isoproterenol(Beta-agonist)
– Vs Beta – blocker (?)
• Temporary transvenous pacing
• Pacemaker implantation
– associated with heart block or bradycardia
• Implantable cardioverter-defibrillators (ICDs)
– cannot be managed by avoidance of the offending agent
Kyunghee Cardiovascular center
Division of cardiology
Circulation. Feb 1988;77(2):392-7
Pacing Clin Electrophysiol. Jan 1993;16(1 Pt 1):33-8
Pacing Clin Electrophysiol. Nov 1997;20(11):2810-6
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