First Aid for the USMLE Step 2 Casebook: A 70-year-old man with increasing shortness of breath
A 70-year-old man presents to the emergency department complaining of increased shortness of breath with minimal exercise, cough, and fatigue. These symptoms began 2 weeks ago and have progressed gradually. He reports he used to feel this way “all the time” years ago, but that this has not happened much since he began using his inhalers and his “water pill.” He also has a history of chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), coronary artery disease (CAD), diabetes mellitus, hypertension, and 30-pack-years of smoking. He denies swelling of the extremities, fever or chills, productive cough, chest pain, or palpitations. He cannot remember the names of his medications, but says he has not missed any doses. When asked about his diet, he says he has been eating more hot soup since the weather has gotten colder. His temperature is 37.5°C (99.5°F), blood pressure is 135/90 mm Hg, heart rate is 90/min, respiratory rate is 18/min, and oxygen saturation is 94% on room air. Examination of the neck reveals mild jugular venous distension. Examination of the lungs reveals loud crackles throughout the lung fields bilaterally. Examination of the heart reveals a laterally displaced point of maximum impulse with no murmurs, rubs, or gallops. There is mild clubbing of the extremities, as well as pitting edema of the lower extremities to the knee, bilaterally. His plasma brain natriuretic peptide level on rapid bedside assay is 500 pg/mL, and an x-ray of the chest reveals perivascular haziness, interstitial edema, and an enlarged cardiac silhouette.
>>>What conditions should be included in the differential diagnosis?
In a patient with a history of CAD, COPD, and CHF who presents with dyspnea on exertion and fatigue, the current condition is likely due to an exacerbation of one of those three underlying diseases. It is of primary importance to distinguish between them when evaluating the presenting symptoms. Shortness of breath as an anginal equivalent can be ruled out by ECG and response to nitrates. However, the causes of COPD and CHF exacerbations are many, and may overlap such that teasing apart the symptomatology proves difficult. Etiologies that, by themselves, can cause gradually worsening shortness of breath and fatigue can include both cardiac and pulmonary diseases, including:
- Heart failure secondary to ischemia/infarction, dysrhythmia, valvular dysfunction, infection, or volume overload
- Lung infections (pneumonia, bronchitis, bronchiectasis)
- Mechanical impairment of ventilation
- Pulmonary edema
- Pulmonary embolism
In addition, these conditions can “tip” patients with underlying COPD or CHF “over the edge.”
>>>What is the most likely diagnosis?
CHF exacerbation leading to pulmonary edema. This patient’s dyspnea, jugular venous distension, and tachypnea in the presence of crackles, pulmonary edema, an elevated brain natriuretic peptide (BNP) level, and cardiomegaly suggest an acute exacerbation of CHF. An exacerbation of COPD is unlikely given that this patient does not have fever, productive cough, or wheezing. Additionally, the patient reported increasing intake of soup, a particularly salty food, which can significantly increase water retention, thereby worsening CHF. A mnemonic for the causes of recurrent CHF is FAILURE:
- Forgot medication
- Lifestyle (increased sodium intake, decreased exercise); most common cause
- Upregulation (increased cardiac output due to pregnancy, hyperthyroidism, etc)
- Renal failure
- Embolus (pulmonary)
>>>How is this condition classified?
The American College of Cardiologists and American Heart Association developed guidelines in 2001 for the classification and treatment of CHF:
|A||High-risk for developing CHF (hypertension, coronary artery disease, diabetes mellitus, or family history), but no evident signs or symptoms||Manage hypertension, smoking, obesity, exercise, hyperlipidemia, alcohol use.Use ACE inhibitors in patients with DM, hypertension, atherosclerosis|
|B||Structural heart disease but have never had symptoms of CHF||ACE inhibitors, beta blockers|
|C||Structural heart disease with prior or current symptoms of CHF||Diuretics, ACE inhibitors, beta blockers, dietary salt restriction, digitalis|
>>>What are the typical laboratory/imaging findings in this condition?
In addition to an x-ray of the chest that may show pulmonary edema, patients with CHF exacerbations may have:
- Decreased hematocrit (anemia may exacerbate CHF)
- Increased potassium, creatinine, and blood urea nitrogen levels (renal failure may exacerbate CHF)
- Increased plasma BNP level, which is usually elevated in CHF exacerbations
- A chest radiograph showing cardiomegaly, cephalization of pulmonary vessels, and/or pleural effusion
- ECG changes showing left ventricular hypertrophy, arrhythmias, or ischemia or low-voltage or old infarcts (in fact, a normal ECG makes systolic dysfunction highly unlikely)
- ECG showing abnormal ventricular size (dilated, hypertrophic, or restrictive cardiomyopathy) or function (systolic or diastolic)
>>>What is the most appropriate management for this patient?
This patient appears to have stage C heart failure as defined by the table above. His physical exam and x-ray of the chest show evidence of myocardial hypertrophy, and he is having current symptoms (recurrent). He should probably be admitted to the hospital for a trial of intravenous diuresis (which often succeeds when oral diuretics fail). Upon clinical improvement and discharge, he should be prescribed an ACE inhibitor (given his atherosclerosis, hypertension, and diabetes mellitus), a diuretic (given his evidence of fluid retention), and digitalis (for symptomatic control). He should also recieve frequent blood pressure monitoring, exercise counseling, possibly spironolactone, and/or an angiotensin receptor blocker. In addition, he should take aspirin and a statin for his CAD, and should have an echocardiogram done to evaluate his ejection fraction and any structural heart disease, namely valvular abnormalities.
This case study was contributed by Brian Ash, MD, Resident in Anesthesia and Perioperative Care, University of California, San Francisco Medical Center; in association with Le TT, Schabelman E, Shivaram A, and Klein J, eds: First Aid Cases for the USMLE Step 2 CK. New York: McGraw-Hill, 2007.
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