Torsades de Pointes due to Excessive Marijuana Use in a Susceptible Patient

Figures

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  Figure 1. (a) Ventricular fibrillation detected by emergency medical services requiring defibrillation; (b) QTc measured in ECG obtained after correction of electrolyte abnormalities (measured by U-wave avoidance technique and calculated by the Bazett Formula: QTc=QT/RR); (c) measurement of QTc from baseline ECG done several years prior.

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  Figure 2. (a) Telemetry strip showing bradycardia with prolonged QTc and R-on-T premature ventricular contraction initiating Torsades de pointes; (b) ECG after starting isoproterenol drip with QTc reduction to 465 msec. (c) ECG showing atrial pacing after placement of dual-chamber ICD, with QTc of 465 msec, prior to starting nadolol.

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  Figure 3. Representation of “the perfect storm” that led up to Tdp and cardiac arrest. Normal QTc several years ago was likely secondary to lack of age/gender-based expression. However, when postpubertal and in the presence of a potent environmental trigger, she developed QTc prolongation and bradycardia resulting in Tdp and cardiac arrest.