A 56-year-old woman is brought to the emergency department due to shortness of breath, which she says began suddenly 2 hours ago while she was enjoying her favorite television show. She also reports sharp, left-sided chest pain that worsens with cough. Medical history includes diabetes mellitus for the past 10 years and hypertension for the past 6 years. Family history is significant for heart disease in her father, who died at age 40. The patient has a 30-pack-year smoking history but does not smoke currently. On physical examination, she is in acute distress and diaphoretic. Temperature is 38.1 C (100.5 F), blood pressure is 110/60 mm Hg, pulse is 140/min and irregular, and respiratory rate is 30/min. Oxygen saturation is 84% on room air by pulse oximetry. BMI is 38 kg/m². Jugular venous pressure is slightly elevated. The lungs are clear to auscultation. Laboratory results are as follows: Chest x-ray is unremarkable. ECG reveals irregular RR intervals with no definite P waves and narrow QRS complexes. Which of the following is the most likely cause of this patient's current symptoms?

Question

Quizplus · Accepted Answer

The manifestations of pulmonary embolism (PE) are nonspecific and variable. Acute-onset dyspnea and pleuritic chest pain are the most common symptoms, occurring in 73% and 66% of patients, respectively. Hemoptysis occurs in <20% and symptoms of deep venous thrombosis in <30%. This patient has multiple physical examination findings consistent with PE, including tachypnea (~55%), tachycardia, hypoxemia, low-grade fever (~5%), and jugular venous distension (~15%). She does not have the classic findings of PE on ECG (ie, prominent S in lead I, Q in lead III, and inverted T in lead III [S1Q3T3]) or chest x-ray (eg, Hampton hump, Westermark sign), but such findings are present in only a minority of cases. Atrial fibrillation (recognized by irregular RR intervals with narrow QRS complexes and an absence of organized P waves) is commonly associated with PE and may result from PE-induced right atrial dilation or increased sympathetic tone. In some cases, the atrial fibrillation may be the cause (rather than result) of PE due to embolization of thrombus from the right atrial appendage into the pulmonary circulation. Hypoxemia and atrial fibrillation are both associated with poor prognosis in PE. (Choice A) Bronchoconstriction (eg, asthma, chronic bronchitis) may present with dyspnea, tachypnea, tachycardia, and hypoxemia. The absence of wheezing and presence of pleuritic chest pain in this patient make bronchoconstriction less likely. Hyperinflation is common on chest x-ray. (Choice B) Cardiac tamponade may present with dyspnea, tachypnea, and tachycardia. However, it is less likely to cause sharp chest pain and hypoxemia, and this patient's lack of distant heart sounds and hypotension make this diagnosis less likely. (Choice C) Mitral stenosis is a common cause of atrial fibrillation resulting from left atrial dilation. However, for mitral stenosis to cause abrupt-onset shortness of breath, pulmonary edema would be expected on chest x-ray. (Choice D) This patient's risk factors for myocardial infarction include hypertension, diabetes, and family history. However, pleuritic chest pain, hypoxemia without pulmonary edema, and the absence of ischemic ECG changes (eg, ST elevation, T wave inversion, Q waves) make PE more likely. (Choice F) Tension pneumothorax presents with acute-onset shortness of breath and pleuritic chest pain. Examination would reveal hypotension and unilaterally absent breath sounds, and chest x-ray is typically diagnostic. Educational objective: The manifestations of pulmonary embolism are nonspecific and variable. The diagnosis should be suspected in any patient who presents with sudden-onset shortness of breath and pleuritic chest pain. Tachypnea, tachycardia, hypoxemia, low-grade fever, and jugular venous distension are common examination findings. References: Findings from 12-lead electrocardiography that predict circulatory shock from pulmonary embolism: systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/26394330)

A 56-Year-Old Woman Is Brought to the Emergency Department Due