Arrhythmias — MCQs

A 73-year-old man noted a rapid onset of severe dizziness and difficulty swallowing while watching TV at home. His wife reports that he had difficulty forming sentences and his gait was unsteady at this time. Symptoms were severe within 1 minute and began to improve spontaneously after 10 minutes. He has had type 2 diabetes mellitus for 25 years and has a 50 pack-year smoking history. On arrival to the emergency department 35 minutes after the initial development of symptoms, his manifestations have largely resolved with the exception of a subtle nystagmus and ataxia. His blood pressure is 132/86 mm Hg, the heart rate is 84/min, and the respiratory rate is 15/min. After 45 minutes, his symptoms are completely resolved, and neurological examination is unremarkable. Which of the following is the most likely cause of this patient’s condition?

A 22-year-old immigrant presents to his primary care physician for a general checkup. This is his first time visiting a physician, and he has no known past medical history. The patient’s caretaker states that the patient has experienced episodes of syncope and what seems to be seizures before but has not received treatment. His temperature is 98.1°F (36.7°C), blood pressure is 121/83 mmHg, pulse is 83/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam is notable for sensorineural deafness. Which of the following ECG changes is most likely to be seen in this patient?

A 68-year-old man presents to the emergency department with palpitations. He also feels that his exercise tolerance has reduced over the previous week. His past history is positive for ischemic heart disease and he has been on multiple medications for a long time. On physical examination, his temperature is 36.9°C (98.4°F), pulse rate is 152/min and is regular, blood pressure is 114/80 mm Hg, and respiratory rate is 18/min. Auscultation of the precordial region confirms tachycardia, but there is no murmur or extra heart sounds. His ECG is obtained, which suggests a diagnosis of atrial flutter. Which of the following findings is most likely to be present on his electrocardiogram?

A 56-year-old man with chronic kidney failure is brought to the emergency department by ambulance after he passed out during dinner. On presentation, he is alert and complains of shortness of breath as well as chest palpitations. An EKG is obtained demonstrating an irregular rhythm with QRS amplitudes that vary in height over time. Other findings include uncontrolled contractions of his muscles. Tapping of his cheek elicits twitching of the facial muscles. Over-repletion of the serum abnormality in this case may lead to which of the following?

A 59-year-old man presents to the emergency department with right-sided weakness and an inability to speak for the past 2 hours. His wife says he was gardening in his backyard when he suddenly lost balance and fell down. The patient has a past medical history of hypertension, diabetes mellitus, and coronary artery disease. Two years ago, he was admitted to the coronary intensive care unit with an anterolateral myocardial infarction. He has not been compliant with his medications since he was discharged. On physical examination, his blood pressure is 110/70 mm Hg, pulse is 110/min and irregular, temperature is 36.6°C (97.8°F), and respiratory rate is 18/min. Strength is 2/5 in both his right upper and right lower extremities. His right calf is edematous with visible varicose veins. Which of the following is the best method to detect the source of this patient’s stroke?

A 33-year-old man presents to the emergency department with severe anxiety. He has had multiple episodes in the past treated with low dose lorazepam. The patient states that he feels as if he is going to die and that he cannot breathe. His past medical history is notable for depression and anxiety. His temperature is 98.1°F (36.7°C), blood pressure is 122/83 mmHg, pulse is 153/min, respirations are 13/min, and oxygen saturation is 98% on room air. The patient is given a low dose of lorazepam and reports a complete resolution of his symptoms. An ECG is performed and demonstrates prolongation of the P-R interval. There is a P wave preceding every QRS complex, no dropped QRS complexes, and the P-R interval does not change. His initial lab values are unremarkable. Which of the following is the best management of this patient?

A 51-year-old man is brought to the local emergency room in severe respiratory distress. The patient is an industrial chemist and was working in his lab with a new partner when a massive chemical spill occurred releasing fumes into their workspace. The patient and his lab partner attempted to clean up the spill before they realized it was too large for them to handle. They were not wearing protective equipment at the time, except for a pair of goggles. The fumes caused them both to begin coughing; however, this patient has a history significant for asthma. His condition worsened, which prompted lab management to call for an ambulance. On arrival at the emergency room, the patient’s respiratory rate is 42/min and oxygen saturation is 96% on room air. He is unable to speak on account of his coughing. He is clearly using accessory muscles with inspiration. A pulmonary exam reveals bilateral wheezes. He is given multiple nebulizer treatments of albuterol and is started on intravenous (IV) methylprednisolone. After 2 successive nebulizer treatments, the arterial blood gas test result shows pH 7.36, partial pressure of carbon dioxide (PCO2) 41 mm Hg, and partial pressure of oxygen (PO2) 79 mm Hg. He is now able to speak and the respiratory rate is 32/min. Which of the following is the best next step in this patient’s management?

An 80-year-old woman presents to her cardiologist for a scheduled appointment. She was shown to have moderate atrial dilation on echocardiography 3 years ago and was started on oral medications. The patient insists that she does not want aggressive treatment because she wants her remaining years to be peaceful. She has not been compliant with her medications and declines further investigations. Her heart rate today is 124/min and irregular. Which of the following organs is least likely to be affected by complications of her condition if she declines further management?

A 22-year-old man is brought to the emergency department 25 minutes after an episode of violent jerky movements of his arms and legs. He has no recollection of the episode. The episode lasted for 3–4 minutes. His girlfriend reports that he has not been sleeping well over the past month. He is only oriented to place and person. His temperature is 37°C (98.6°F), pulse is 99/min, respirations are 18/min, and blood pressure is 110/80 mm Hg. Neurologic examination shows no focal findings. A complete blood count as well as serum concentrations of glucose, electrolytes, and calcium are within the reference range. Urine toxicology screening is negative. An MRI of the brain shows no abnormalities. Which of the following is the most appropriate next step in management?

A 67-year-old woman comes to the emergency department 1 hour after her husband saw her faint shortly after getting out of bed from a nap. She regained consciousness within 30 seconds and was fully alert and oriented. She has had 2 similar episodes in the last 5 years, once while standing in line at the grocery store and once when getting out of bed in the morning. 24-hour Holter monitoring and echocardiography were unremarkable at her last hospitalization 1 year ago. She has hypertension, depression, and asthma. Current medications include verapamil, nortriptyline, and an albuterol inhaler as needed. Her temperature is 37°C (98.4°F), pulse is 74/min and regular, respirations are 14/min, blood pressure is 114/72 mm Hg when supine and 95/60 mm Hg while standing. Cardiopulmonary examination shows no abnormalities. Neurologic examination shows no focal findings. A complete blood count and serum concentrations of electrolytes, urea nitrogen, creatinine, and glucose are within the reference range. Bedside cardiac monitoring shows rare premature ventricular contractions and T-wave inversions in lead III. Which of the following is the most likely cause of this patient's symptoms?