Cardiac Tamponade USMLE

Definitive question for Cardiac tamponade USMLE Step 2 /3

Cardiac tamponade USMLE question no 1.

  1. A 60-year-old man with a history of aortic stenosis who underwent surgical valve replacement 4 days ago presents for a follow-up visit. He complains of severe chest pain that woke him up that morning, as well as fatigue, dyspnea, and anorexia. On physical examination, he has elevated jugular venous pressure and soft heart sounds. The rest of her examination findings are benign, although his extremities feel slightly cool. His temperature is 37°C (98.6°F), the pulse is 94/min, blood pressure is 78/58 mmHg, respiratory rate is 24/min, and oxygen saturation is 100% on room air. An ECG is ordered. What ECG findings will support the suspected diagnosis in this patient?

    A. Alternation of QRS complex amplitude between beats

    B. An ECG cannot be used to support the diagnosis for this case

    C. Diffuse ST-segment elevation on ECG

    D. Irregularly irregular rhythm

    E. ST-segment depression

The correct answer is option A. This patient has signs and symptoms consistent with cardiac tamponade, including chest pain, dyspnea, and fatigue. His JVD, distant heart sounds, and recent cardiac surgery also support this diagnosis. The classic ECG finding seen in cardiac tamponade is electrical alternans. Electrical alterans describes the alternation of QRS complex amplitude between heartbeats throughout the ECG
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Cardiac tamponade USMLE question no 2

2. A 35-year-old woman arrives at the emergency department after being stabbed. She was intubated by the emergency medical staff at the scene. On arrival, she is pale and diaphoretic, blood pressure is 74/54 mm Hg, and the pulse is 140/min. A quick initial survey reveals entry wounds in her left chest and upper abdomen. Breath sounds are equal bilaterally and the abdomen is non-tender. Her neck and forehead veins are enlarged and distended. As intravenous fluids are started, her systolic blood pressure drops to 40 mm Hg, no distal pulses can be felt, and she loses consciousness. Which of the following is the best next step in management?

A. Abdominal ultrasound

B. Administration of 2 units of packed RBCs

C. Chest tube placement

D. CT of chest and abdomen

E. Pericardiocentesis

The correct answer is option E. This patient has acute pericardial tamponade, which is the accumulation of blood in the pericardial sac. This is a clinical diagnosis that is suggested by hypotension with distended neck veins and a stab wound to the left chest in this patient. Other findings may include distant heart sounds, increased heart rate, Kussmaul’s sign (increased jugular venous pressure on inspiration), and pulsus paradoxus. In acute pericardial tamponade, there is an equalization of diastolic pressure in all four chambers. This causes impaired diastolic filling and reduced cardiac output. Evacuation of the blood with pericardiocentesis will produce an instant improvement in the patient’s symptoms
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Cardiac tamponade USMLE question no 3

3. A 48-year-old man with a history of stable angina and a positive exercise stress test presents for cardiac catheterization. During the procedure, he develops tachycardia and becomes hypotensive. The anesthesiologist notices that his systolic pressure falls even further on inspiration. His ECG shows QRS variation with each impulse. Which treatment will most likely lead to a resolution of this patient’s tachycardia and hypotension?

A. Chest tube placement

B. Emergent pericardiocentesis

C. Intravenous fluids

D. Loop diuretics

E. Nitroglycerin

The correct answer is option B. The ECG features demonstrate electrical alternans, which is a sign of fluid in the pericardial sac. This patient has likely developed cardiac tamponade secondary to laceration of a coronary artery during catheterization. If the fluid is rapidly introduced into the pericardium, it cannot stretch to accommodate the additional volume; therefore, the intrapericardial pressure rises quickly. A very small volume of fluid in the pericardium can lead to tamponade if introduced rapidly enough, as seen in this patient. During cardiac tamponade, high intrapericardial pressure limits the amount of venous return and thus cardiac output. Hypotension and compensatory tachycardia follow. Emergent pericardiocentesis is recommended in the case of cardiac tamponade in a hemodynamically unstable patient.
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Cardiac tamponade usmle
Electrical alternans, tachycardia and low voltage in a person with a large pericardial effusion.
James Heilman, MD / CC BY-SA

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