USMLE PRACTICE QUESTION #46
TOPIC: Patient Management (Cardiovascular Medicine)
Today’s question will test your ability to perform two crucial USMLE tasks: Make a diagnosis and identify the most appropriate next step in management.
A 54-year-old female presents to the emergency department with palpitations and lightheadedness that started suddenly while gardening earlier in the day. She has a history of hypertension, well-controlled with hydrochlorothiazide 25 mg daily. Her vital signs are: temperature 98.4°F (36.9°C), blood pressure 112/70 mmHg, heart rate 160/minute, respiratory rate 16/minute, and oxygen saturation 98% on room air. A physical exam revealed clear lung fields and no jugular venous distention or lower extremity edema. Cardiac auscultation demonstrates an irregularly irregular rhythm without murmurs or gallops. Electrocardiogram reveals atrial fibrillation with a rapid ventricular response. Labs show a normal complete blood count, basic metabolic panel, and troponin level. Chest X-ray is unremarkable. The patient has no history of heart failure, valvular disease, or syncope. Which of the following is the most appropriate next step in managing this patient?
A) Transesophageal echocardiogram
B) Cardiac magnetic resonance imaging
C) Electrophysiology study
D) Exercise stress test
E) 24-hour Holter monitor
F) Rate control with IV beta-blockade
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The mental model for this question comes from our detailed test-taking skills masterclass (if you’re struggling with USMLE questions, be sure to check it out). Here’s how to think through this question:
Step 1. Determine what the question is asking: What’s the most appropriate next best step in caring for the patient?
Ask yourself: Is this a first, second, or third-order question?
Answer: It’s second-order (need to diagnose to know the next best step in management)
Step 2. Read the vignette to determine a diagnosis.
Step 3. Ask yourself what you should do based on the diagnosis and the patient’s current state.
Step 4. Look at the answer choices and select the option most closely resembling your thoughts from “Step 3” above.
GENERAL ANALYSIS
This question involves a 54-year-old female presenting with palpitations and lightheadedness, diagnosed with atrial fibrillation with a rapid ventricular response. The primary concern is to manage her symptoms and prevent complications by controlling her heart rate. The question asks for the most appropriate next step in her care.
ANSWER CHOICES:
ANSWER CHOICE A: Transesophageal echocardiogram
TEE can visualize the heart's structures and is useful in checking for thrombi in the left atrium before cardioversion. While helpful in assessing thrombi, TEE is not the immediate step for managing rapid heart rate in atrial fibrillation.
ANSWER CHOICE B: Cardiac magnetic resonance imaging
MRI provides detailed images of the heart's structure and function. MRI is not typically used in the acute management of atrial fibrillation as it doesn’t address the immediate need for rate control.
ANSWER CHOICE C: Electrophysiology study
An electrophysiology study is used to examine the heart's electrical activity and diagnose arrhythmias. It is not an immediate intervention for rate control in atrial fibrillation.
ANSWER CHOICE D: Exercise stress test
This test evaluates the heart's response to physical stress. It is not relevant to the acute management of atrial fibrillation with rapid ventricular response.
ANSWER CHOICE E: 24-hour Holter monitor
A Holter monitor records the heart's electrical activity over 24 hours. This is used for long-term monitoring, not for immediate rate control.
ANSWER CHOICE F: Rate control with IV beta-blockade
Intravenous beta-blockers, such as metoprolol, effectively control the heart rate quickly by slowing conduction through the AV node. Rate control is the primary goal in managing atrial fibrillation with rapid ventricular response, and IV beta-blockers are a standard treatment to achieve this.
FINAL VERDICT…
In atrial fibrillation with a rapid ventricular response, the management goal is to control heart rate to alleviate symptoms and prevent hemodynamic instability. IV beta-blockers, like metoprolol, are effective for rapid rate control. They work by slowing conduction through the AV node, reducing the ventricular rate. This approach is particularly suitable for patients without contraindications to beta-blockers and helps stabilize the patient's condition quickly.
CORRECT ANSWER: F) Rate control with IV beta-blockade
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