Torsades de pointes: Difference between revisions

Revision as of 06:45, 5 April 2019

Background

Form of polymorphic VTach
- Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
Associated with congenital or acquired prolonged QT

Common Causes

POINTES mnemonic:

Phenothiazines
Other medications (ie TCAs)
Intracranial bleed
No known cause (idiopathic)
Type I anti-arrhythmics (quinidine, procainamide, disopyramide)
Electrolyte abnormalities (hypoK & hypoMag)
Syndrome of Prolonged QT (aka Long QT Syndrome)

Clinical Features

Syncope
Dizziness
Lightheadedness
Palpitations
Sudden Cardiac Death

Differential Diagnosis

Drug induced
Congenital long QT
Hypocalcemia
Hypomagnesemia
Hypokalemia
Hypothermia
POINTES as above

Wide-complex tachycardia

Assume any wide-complex tachycardia is ventricular tachycardia until proven otherwise (it is safer to incorrectly assume a ventricular dysrhythmia than supraventricular tachycardia with abberancy)

Regular
- Monomorphic ventricular tachycardia
- PSVT with aberrant conduction:
  - PSVT with bundle branch block^
  - PSVT with accessory pathway
  - Atrial flutter with bundle branch block^
- Sinus tachycardia with bundle branch block^
- Accelerated idioventricular rhythm (consider if less than or ~120 bpm)
- Metabolic
  - Hyperkalemia
  - Digoxin toxicity
  - Severe metabolic acidosis
Irregular
- Atrial fibrillation/atrial flutter with variable AV conduction AND bundle branch block^
- Atrial fibrillation/atrial flutter with variable AV conduction AND accessory pathway (e.g. WPW)
- Atrial fibrillation + hyperkalemia
- Polymorphic ventricular tachycardia
  - Torsades de pointes
  - Nonsustained ventricular tachycardia

^Fixed or rate-related

Evaluation

Workup

ECG
BMP, Mg, Phos

Diagnosis

Classic torsades in 12-lead

Torsades de Pointes (TdP) in patient with a potassium of 2.4 mmol/L and a magnesium of 1.6mg/dL.

ECG showing the QRS complexes “twisting” around the isoelectric line

Management

Increasing HR decreases QT interval

Magnesium sulfate - decreases calcium influx
- 1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
  - Danger of hypermagnesemia → depressed neuromuscular function and respiratory drive, so monitor closely
  - Supplement with K+
Isoproterenol - Increases HR / AV conduction
- 2-8 mcg/min
- Target HR > 90 bpm
Overdrive Pacing - Atrial > Ventricular pacing
- Goal HR 90-120
- Note: Not a treatment for TdP, but useful in maintaining sinus rhythm
Defibrillation / synchronized cardioversion - Patient in extremis
AVOID amiodarone and procainamide, which may worsen prolonged QT
Lidocaine (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes.

Disposition

Admit

References

Authors:

@@ Line 1: / Line 1: @@
 ==Background==
-*Most commonly occurs in pts w/ prolonged QT due to heart diseaes or meds:
+*Form of polymorphic VTach
-**Procainamide
+**Gradual change in the amplitude of QRS complexes and twisting around isoelectric line
-**Phenothiazine
+*Associated with congenital or acquired [[prolonged QT]]
-**TCAs
-**Qunidine
-**Disopyramide
-==Treatment==
+===Common Causes===
-#Magnesium
+'''POINTES''' mnemonic:
-##1-2gm IV over 1-2 min; then 1-2gm/hr gtt
+*'''P'''henothiazines
-#[[Overdrive Pacing]]
+*'''O'''ther medications (ie TCAs)
-##Goal HR 90-120
+*'''I'''ntracranial bleed
-#Isoproterenol
+*'''N'''o known cause (idiopathic)
-##2-8 mcg/min
+*'''T'''ype I anti-arrhythmics (quinidine, procainamide, disopyramide)
+*'''E'''lectrolyte abnormalities (hypoK & hypoMag)
+*'''S'''yndrome of Prolonged QT (aka Long QT Syndrome)
+==Clinical Features==
+*Syncope
+*Dizziness
+*Lightheadedness
+*Palpitations
+*Sudden Cardiac Death
+==Differential Diagnosis==
+*Drug induced
+*Congenital long QT
+*Hypocalcemia
+*Hypomagnesemia
+*Hypokalemia
+*Hypothermia
+*POINTES as above
+{{Tachycardia (wide) DDX}}
+==Evaluation==
+===Workup===
+*[[ECG]]
+*BMP, Mg, Phos
+===Diagnosis===
+[[File:12leadTorsade.jpg|thumb|Classic torsades in 12-lead]]
+[[File:Torsades de Pointes TdP.png|thumb|Torsades de Pointes (TdP) in patient with a potassium of 2.4 mmol/L and a magnesium of 1.6mg/dL.]]
+*[[ECG]] showing the QRS complexes “twisting” around the isoelectric line
+==Management==
+Increasing HR decreases QT interval
+#[[Magnesium sulfate]] - decreases calcium influx
+#*1-2gm IV over 1-2 min, repeat in 5-15min; then 1-2gm/hr (3-10mg/min) drip
+#**Danger of [[hypermagnesemia]] → depressed neuromuscular function and respiratory drive, so monitor closely
+#**Supplement with K+
+#[[Isoproterenol]] - Increases HR / AV conduction
+#*2-8 mcg/min
+#*Target HR > 90 bpm
+#[[Overdrive Pacing]] - Atrial > Ventricular pacing
+#*Goal HR 90-120
+#*Note: Not a treatment for TdP, but useful in maintaining sinus rhythm
+#[[Defibrillation]] / [[synchronized cardioversion]] - Patient in extremis
+#'''AVOID''' amiodarone and procainamide, which may worsen prolonged QT
+# Lidocaine (a class Ib antiarrhythmic drug) shortens the QT interval and may be effective especially for drug-induced torsades de pointes.
+==Disposition==
+*Admit
 ==See Also==
@@ Line 19: / Line 65: @@
 *[[ACLS (2010 Guidelines)]]
-==Source ==
+==References==
-*Tintinalli
+<references/>
-[[Category:Cards]]
+[[Category:Cardiology]]