ECG Challenge

Drug Abuse Follows a Broken Heart

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A 26-year-old man is brought to the emergency department (ED) by three friends who hadn’t seen him for two days and went to his apartment to check on him. They found him unconscious on the floor with four empty syringes on the coffee table beside him. The patient was aroused with difficulty but remained incoherent. Rather than call 911, they carried him to their car and brought him to the ED. According to his friends, he has been an IV drug abuser since breaking up with his girlfriend two years ago. He has been increasingly despondent over the past few days after seeing her with anoth-er man. The friends state that they know he has used heroin, cocaine, marijuana, and methamphet-amines in the past, but do not know what he used on this occasion. He has not had any prior illnesses, surgical procedures, or medical conditions that they are aware of. They do not know whether the patient is taking any prescription medications, nor whether he is aller-gic to any medications. According to one of the friends, the patient works with him as a welder at a local factory. He states the patient has been absent from work since last seeing his ex-girlfriend. You are unable to obtain a review of systems. A cursory examination reveals a thin, disheveled male who is unconscious but arousable. Blood pressure is 102/62 mm Hg, and pulse, 110 beats/min. Res-pirations are shallow at a rate of 20 breaths/min-1. Examination of the skin is remarkable for multiple recent and mature needle tracks in both upper ex-tremities, as well as multiple excoriations and shallow ulcers on both lower extremities. The EENT exam is remarkable for constricted pupils that react to light. Corneal reflexes are intact. The teeth are in poor repair with multiple caries and missing teeth. The neck veins are not distended, the thyroid is normal, and there are palpable lymph nodes in the left anterior cervical chain. The lungs have diffuse, scattered dry rales. The cardiac exam reveals a regular rate at 110 beats/min with a soft, early systolic murmur best heard at the left upper sternal border. A rub is also present. Peripheral pulses are equal bilaterally in both upper and lower extremities. The abdomen is soft and nontender. The liver edge is palpable 2 cm below the right costal margin, and a firm spleen is palpable on the left. The neurologic exam reveals hyperactive deep tendon re-flexes in all four extremities. Laboratory samples are drawn; results are positive for cocaine, cannabis, and methamphetamine. Stat blood cultures are positive for Staphylococcus aureus, and the white blood count is 21,000/μL. A bedside echocardiogram performed in the ED shows evidence of a pericardial effusion and a perivalvular abscess on the septal side of the mitral valve, consistent with endocarditis. Prior to the patient’s transport to radiology for a CT scan, a quick ECG is performed. It reveals a ven-tricular rate of 110 beats/min; PR interval, 130 ms; QRS duration, 76 ms; QT/QTc interval, 352/476 ms; P axis, 59°; R axis, 96°; and T axis, 106°. What is your interpretation of this ECG?


 

ANSWER
This ECG shows sinus tachycardia at a rate of 110 beats/min, evidenced by the presence of a P wave for every QRS complex with regular R-R intervals. Left atrial enlargement is evident from the presence of P waves ≥ 110 ms (admittedly difficult to see in this example) and a terminal negativity of the P wave in lead V1 ≥ 1 mm2. A rightward axis is evidenced by the presence of an R-wave axis of 96°; however, it does not meet criteria for a true right-axis deviation 
(≥ 105°). Nonspecific T-wave abnormalities are observed in leads V5 and V6.

The most intriguing aspect of this ECG is observed in lead V3. Note the abrupt disruption of R-wave progression between leads V2 and V4. This was due to incorrect placement of the ECG electrode for V3, which occurred in the haste to obtain the ECG prior to the CT scan. This illustrates the importance of correct electrode placement for an accurate tracing.

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