A 28-year-old man comes to the emergency department with a 3-day history of increasing chest tightness and intermittent sharp chest pains. He also reports mild dyspnea, especially on exertion. The patient has no prior chronic medical conditions but had an upper respiratory illness a week ago that resolved without treatment. ECG reveals sinus tachycardia and low voltage QRS complexes that vary in the amplitude from beat to beat. Which of the following is the most likely chest x-ray finding in this patient?

Question

A 28-year-old man comes to the emergency department with a 3-day history of increasing chest tightness and intermittent sharp chest pains.  He also reports mild dyspnea, especially on exertion.  The patient has no prior chronic medical conditions but had an upper respiratory illness a week ago that resolved without treatment.  ECG reveals sinus tachycardia and low voltage QRS complexes that vary in the amplitude from beat to beat.  Which of the following is the most likely chest x-ray finding in this patient?

Quizplus · Accepted Answer

11ec160b_355f_9374_9249_757ee657b9bb_MD0001_00 This patient with a recent history of upper respiratory infection has likely developed viral pericarditis complicated by pericardial effusion. Viral infection is the most common cause of acute pericarditis, with coxsackievirus (types A and B) and echovirus being the most common organisms. Patients with pericarditis typically experience chest pain, which may be intermittent (as in this patient) but is often pleuritic and/or positional (eg, relieved by leaning forward). As in this patient, viral pericarditis can be complicated by pericardial effusion due to fibrinous or serofibrinous pericardial inflammation. Symptoms of pericardial effusion may include a sensation of chest tightness or fullness and dyspnea on exertion (due to decreased diastolic ventricular filling that leads to decreased stroke volume). In addition, pericardial effusion often causes the following clinical findings: Tachycardia to compensate for decreased ventricular filling Low voltage QRS on ECG and diminished heart sounds to auscultation due to pericardial fluid accumulation increasing the distance between the heart and the ECG leads or stethoscope Electrical alternans on ECG due to the swinging motion of the heart in the fluid-filled pericardial cavity, causing a beat-to-beat variation in the QRS axis Patients with pericardial effusion classically have an enlarged, globular cardiac silhouette on chest x-ray, which occurs when progressive pericardial stretching over days to weeks (ie, subacute course) allows large volumes (eg, up to 1-2 L) of pericardial fluid to accumulate. Clear lung fields are typically seen because the increase in pericardial pressure (due to pericardial fluid accumulation) affects the lower pressure, right-sided heart chambers more than the left-sided heart chambers. When right-sided obstruction to blood flow is greater than left-sided obstruction, pulmonary edema is unlikely to develop. (Choice B) Hyperinflated lungs with increased bronchial markings are commonly seen in patients with chronic obstructive pulmonary disease. (Choice C) Bilateral patchy infiltrates (perihilar > peripheral) are concerning for pulmonary edema. A normal cardiac silhouette may be present (as in this x-ray) due to an acute cardiac process (eg, MI) that causes acute systolic dysfunction and pulmonary congestion. In contrast, pulmonary edema in the setting of cardiomegaly is often due to chronic heart failure. (Choice D) Absence of right-sided, peripheral lung markings surrounding a small, collapsed lung is consistent with a large right-sided pneumothorax. (Choice E) Blunting of the right costophrenic angle and loss of diaphragmatic contour are characteristic of a pleural effusion. Educational objective: Acute viral pericarditis is commonly complicated by pericardial effusion. Classic features of pericardial effusion include tachycardia and ECG findings of low voltage QRS and electrical alternans. Chest x-ray classically reveals an enlarged cardiac silhouette with clear lungs. __________ References: Diagnosis and management of pericardial effusion. (http://www.ncbi.nlm.nih.gov/pubmed/21666814)

A 28-Year-Old Man Comes to the Emergency Department with a 3-Day