A 45-year-old man comes to the emergency department due to shortness of breath. His symptoms began when he woke up today and have not diminished since. The patient also reports mild chest pressure but has no cough, fever, wheezing, or chest pain. He was diagnosed with idiopathic membranous nephropathy 6 months ago during evaluation of anasarca, and cyclophosphamide and prednisone therapy were begun due to persistent heavy proteinuria. The patient is a lifelong nonsmoker and does not use alcohol or illicit drugs.
Temperature is 37.2 C (99.0 F), blood pressure is 144/84 mm Hg, pulse is 112/min and regular, and respirations are 18/min. Oxygen saturation is 91% while breathing ambient air. There is no jugular venous distension. The lungs are clear on auscultation, and cardiac examination shows no abnormalities with the exception of tachycardia. The patient has 2+ bilateral, lower extremity pitting edema. There is no calf tenderness.
Laboratory results are as follows:
ECG shows sinus tachycardia with nonspecific ST-T changes.
Which of the following conditions is most likely associated with this patient's current symptoms?

Question

A 45-year-old man comes to the emergency department due to shortness of breath.  His symptoms began when he woke up today and have not diminished since.  The patient also reports mild chest pressure but has no cough, fever, wheezing, or chest pain.  He was diagnosed with idiopathic membranous nephropathy 6 months ago during evaluation of anasarca, and cyclophosphamide and prednisone therapy were begun due to persistent heavy proteinuria.  The patient is a lifelong nonsmoker and does not use alcohol or illicit drugs.
Temperature is 37.2 C (99.0 F), blood pressure is 144/84 mm Hg, pulse is 112/min and regular, and respirations are 18/min.  Oxygen saturation is 91% while breathing ambient air.  There is no jugular venous distension.  The lungs are clear on auscultation, and cardiac examination shows no abnormalities with the exception of tachycardia.  The patient has 2+ bilateral, lower extremity pitting edema.  There is no calf tenderness.
Laboratory results are as follows:
 ECG shows sinus tachycardia with nonspecific ST-T changes.
Which of the following conditions is most likely associated with this patient's current symptoms?

Quizplus · Accepted Answer

11ec193a_98fa_4a5a_853d_c5f153aee6e9_MD0002_00 This patient with membranous nephropathy (a nephrotic syndrome) and acute-onset shortness of breath, chest pain, and tachycardia likely has a pulmonary embolism (PE). In patients with nephrotic syndrome, PE is often the presenting manifestation of chronic renal venous thrombosis (RVT). Patients with nephrotic syndrome (urine protein >3.5 g/day, albumin <3 g/dL, edema) have a markedly increased risk of (venous > arterial) thrombosis, with 12%-30% of patients developing PE. The hypercoagulable state is likely due to both urinary loss of antithrombin III and plasminogen and increased levels of fibrinogen with platelet activation. Membranous nephropathy, the most common cause of nephrotic syndrome, carries the highest risk of thrombosis; up to 60% of patients with membranous nephropathy will develop RVT. This risk is particularly high in patients with >10 g/day of urinary protein or <2 g/dL of serum albumin. RVT that develops in membranous nephropathy is typically chronic, asymptomatic, and often not associated with worsening renal function or proteinuria (as opposed to acute RVT, which presents with pain, hematuria, and renal failure). The thrombus can propagate into the inferior vena cava and embolize into the pulmonary vasculature, resulting in PE (often the only manifestation of chronic RVT). Diagnosis of RVT can be made by selective venography, Doppler ultrasound, CT scan, or MRI; however, routine screening in membranous nephropathy is not recommended. Treatment is anticoagulation. (Choice A) Cyclophosphamide pulmonary toxicity typically results in a pneumonitis with symptoms of cough, fatigue, and dyspnea. It would be unlikely to cause acute chest pain, tachycardia, and a troponin elevation. (Choice B) Right coronary artery myocardial infarction causes an inferior wall myocardial infarction, which in turn causes chest pain and dyspnea; however, an ECG would show ST elevations in the inferior leads (II,III, and aVF). If the right ventricle is involved, hypotension and elevated jugular venous pressure will predominate. The troponin elevation is likely due to right heart strain from acute PE. (Choice C) Pericardial effusions can cause shortness of breath and tachycardia; however, patients typically have elevated jugular venous distension, hypotension, and low voltages on ECG. (Choice D) Bilateral renal artery stenosis can cause flash pulmonary edema (Pickering syndrome); however, this typically presents with hypoxia, severe hypertension, and jugular venous distension. Educational objective: Nephrotic syndrome, particularly membranous nephropathy, is associated with a high frequency of thromboembolic events, predominately deep venous and renal venous thrombosis. Renal venous thrombosis is often asymptomatic; pulmonary embolism may be the presenting sign. __________ References: High absolute risks and predictors of venous and arterial thromboembolic events in patients with nephrotic syndrome: results from a large retrospective cohort study. (http://www.ncbi.nlm.nih.gov/pubmed/18158362) Thromboembolic complications in the nephrotic syndrome: pathophysiology and clinical management. (http://www.ncbi.nlm.nih.gov/pubmed/15990160)

A 45-Year-Old Man Comes to the Emergency Department Due to Shortness