This 32-year-old woman is found unconscious by a friend on her apartment’s floor. Near her was an empty medication bottle:

• Sinus rhythm, 63/min
• Wide P waves (P wave duration 200 msec)
• First degree AV block (PR = 240 msec)
• Right bundle branch block
• Marked prolongation of the QT interval (QT = 614 msec., QTc = 614 msec.)
• Tricyclic antidepressant overdose is a strong probability

Comments: Urine toxicology screen showed the presence of benzodiazepine, cocaine metabolites and tricyclic antidepressant (TAD) metabolites. The empty  bottle found on the floor near the patient had contained amitryptyline. The most important toxic effect of TADs is the slowing of the depolarization by inhibition of sodium influx with delay of conduction in the myocardium and conducting tissue. This explains the marked PR, QRS and QT prolongation. Marked PR, QRS and QT prolongation in the ECG of a patient found comatose strongly suggests the possibility of TAD overdose.

ref:  G W Kerr, A C McGuffie, S Wilkie – Tricyclic antidepressant overdose: a review Emerg Med J 2001;18:236-241

The patient was intubated and ventilated in the Emergency Department and admitted to the ICU. She received sodium bicarbonate IV. ECG 2 was recorded 37 hours after the first tracing (ECG 1). The patient had become responsive, but she still required ventilation:

Comments: Brugada type 1pattern has been noted in the ECG of patients with tricyclic antidepressant overdose.

E.G.Yap, E.R.Behr, A.J.Camm – Drug-induced Brugada: Tricyclic  Antidepressants – www.medscape.com/viewarticle/712193_5

The clinical course was complicated by staphylococcus aureus pneumonia, which made weaning from ventilation and extubation very difficult. Significant improvement of the ECG was noted 1 week after admission:

• Sinus rhythm, 78/min
• Rightward axis

• Prolonged QT (QT = 422 msec, QTc = 481 msec)

The patient made a complete recovery. This ECG is recorded just prior to discharge from hospital (10 days after admission):

• Normal sinus rhythm
• Normal ECG