An 80-year-old woman with dyspnea on exertion for a month was referred to our cardiology outpatient clinic. The month before her presentation, the patient remained at home where she was only performing household chores due to severe symptoms of depression. She developed dyspnea on exertion after her depression improved.
Her vital signs on presentation were as follows: temperature 97.7°F (36.5°C), blood pressure 101/57 mm Hg, heart rate 84 beats per minute, and oxygen saturation 96% at rest while breathing room air, decreasing to 88% after walking.
Physical examination revealed a systolic murmur that was loudest at the left middle to lower sternum (intensity grade 2 of 6).
Laboratory test results revealed significantly elevated levels of D-dimer at 3.4 μg/mL (reference range ≤ 1.0) and brain natriuretic peptide at 40.5 pg/mL (≤ 18.5). Troponin and arterial blood gas tests were not performed.
Electrocardiogram showed normal sinus rhythm, prolonged PQ interval, narrow QRS complex, and negative T wave at lead III; it also detected a dilated right ventricle and D-shaped left ventricle at systole. Chest radiograph revealed a focal area of oligemia (or reduced blood flow), known as the Westermark sign, in the middle and upper zones of the right lung (Figure 1). Contrast-enhanced computed tomography confirmed a predominantly right pulmonary artery embolism (Figure 2).
Chest radiography showed a focal area of oligemia, known as the Westermark sign, in the right middle and upper zone (white arrow) and an enlarged right descending pulmonary artery (black arrow).
Contrast-enhanced computed tomography showed emboli in the right pulmonary artery (arrows).
The patient was diagnosed with pulmonary embolism. She was started on anticoagulation treatment with intravenous heparin and transitioned to oral warfarin, and her symptoms improved.
THE WESTERMARK SIGN
Our patient presented with shortness of breath and oxygen desaturation, but her Wells score was 3, based on her meeting only 1 of 7 Wells criteria, ie, that pulmonary embolism was a more likely diagnosis than others, which is a somewhat subjective finding. The Wells criteria she did not meet were symptoms of deep vein thrombosis (3 points); heart rate over 100 beats per minute, immobilization for 3 or more days or surgery in the previous 4 weeks, and previously diagnosed deep vein thrombosis or pulmonary embolism (1.5 points each); and hemoptysis and active malignancy (1 point each).1 Her score of 3 indicated that pulmonary embolism was unlikely (pulmonary embolism is likely with a score > 4). Also, the positive D-dimer complicated the clinical assessment in this case and was challenging to interpret without additional testing.1 Therefore, finding a Westermark sign on this patient’s chest radiograph added important clinical information.
The Westermark sign is a radiographic finding seen in pulmonary embolism; it represents decreased vascularization due to mechanical obstruction or reflex vasoconstriction in the area distal to the occluded pulmonary artery. It has low sensitivity (14%) and high specificity (92%) when compared with computed tomographic pulmonary angiography, the current gold standard for identifying pulmonary embolism.2
In this case, pulmonary embolism was strongly suspected due to the Westermark sign on chest radiograph, elevated D-dimer, and clinical symptoms; contrast-enhanced computed tomography was performed to confirm the diagnosis. Because the Westermark sign has low sensitivity, chest radiography alone cannot be used to make or rule out a pulmonary embolism diagnosis. However, clinicians should be aware that findings of pulmonary embolism seen on a chest radiograph, such as the Westermark sign, can aid in prompt diagnosis and treatment.
DISCLOSURES
The authors report no relevant financial relationships which, in the context of their contributions, could be perceived as a potential conflict of interest.
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