A 73-year-old woman is brought in by paramedics after fainting in the mall and hitting her face. She does not remember any preceding symptoms, and she did not lose control of her bowel or bladder. Witnesses at the scene say that she was down for less than a minute, then woke up and was fairly alert. She was bleeding from a laceration on her chin and paramedics were called. When she arrived at the hospital, her initial laboratory values were normal and an EEG did not show epileptiform activity. She is placed on a cardiac monitor. The following day, she becomes lightheaded and loses consciousness while lying in bed, and her monitor shows tachycardia with the QRS complexes being uniformly longer than 120 ms.
What is the most common cause of this rhythm disturbance?A) Uncontrolled hypertension
Ischemic heart disease. The vignette describes an episode of ventricular tachycardia, which is indicated by the wide QRS complexes on her monitor. A serious arrhythmia should have been high on the differential given her episode of syncope with the red flag of head trauma, indicating a very sudden loss of consciousness without any ability to brace herself, which is typical of a cardiac etiology. The most common cause of ventricular tachycardia is ischemic heart disease. Patients that suffer a myocardial infarction have scarring of the myocardium that disrupts the normal electrical pathways and increases the risk of developing this dangerous rhythm. (A, C) Uncontrolled hypertension and accessory pathways are not the most common causes of ventricular tachycardia. (B) Distention of the pulmonary veins is thought to be a mechanism of atrial fibrillation.