Falling for the Heart: A Pericardial Effusion
A 69-year-old woman with a past medical history of squamous cell carcinoma of the tongue status post definitive concurrent chemotherapy and radiation 10 years prior, stage 1A breast cancer (invasive ductal carcinoma) status post left mastectomy on adjuvant hormonal therapy 2 years prior, vitamin B12 deficiency, congenital absence of the thyroid, hypertension, depression, degenerative disk disease, and gout presented with a fall, following six months of 30-pound weight gain, fatigue, and lower extremity weakness.
In the Emergency Department, the patient was noted to have low voltage QRS complexes on electrocardiogram without electrical alternans (Figure 1). Chest x-ray demonstrated an enlarged cardiac silhouette with a small right-sided pleural effusion but no pulmonary edema (Figure 2). Echocardiogram was performed revealing a moderate-sized posterior pericardial effusion measuring up to 1.6 cm and a small pericardial effusion anteriorly to the right ventricle (Figure 3). There was no tamponade physiology seen, as evidenced by several findings. The inferior vena cava measured 2.4 cm in diameter and decreased by greater than 50% with inspiration. Doppler assessment across the mitral and tricuspid valve revealed the respiratory inflow variation was 15% and 59%, respectively. Finally, there was no diastolic chamber collapse. Gated cardiac computed tomography angiography (CTA) demonstrated a circumferential pericardial effusion with simple fluid and no pericardial thickening or thoracic malignancy (Figure 4).
On physical examination, the patient appeared pale and her skin was coarse. She was overweight. Body temperature was 98.6 F°, pulse was 71 beats per minute, blood pressure was 122/73, respiratory rate was 14 breaths per minute, and oxygen saturation was 100% on room air. Cardiovascular examination revealed a normal S1 and S2, with no pericardial rub or murmurs. There was no jugular venous distention or pulsus paradoxus. Trace edema was present in the lower extremities.
Electrolytes and kidney function were normal. Complete blood cell count showed a hemoglobin of 11.5 g/dL (normal range: 11.5-15.5 g/dL) with a mean corpuscular volume (MCV) of 97.9 fL (normal range: 80.0-100.0 fL), white blood cell count of 6.5 k/uL (normal range: 3.70-11.00 k/uL), and platelet count of 271 K/uL (normal range: 150-400 k/uL). High sensitivity C-reactive protein was 2.6 mg/L (normal range: <1.0 mg/L) and erythrocyte sedimentation rate was 33 mm/hr (normal range: 0-20 mm/hr). Rheumatoid factor and antinuclear antibody (ANA) were negative. NT-proBNP was 194 pg/mL (normal range: <125 pg/mL). Thyroid-stimulating hormone (TSH) level was 102.6 uIU/mL (normal range: 0.400-5.500 uIU/mL), with free T4 of 0.54 pg/mL (normal range: 0.9-1.7 ng/dL) and free T3 of 1.1 ng/dL (normal range: 79-165 ng/dL).
What is the most likely pathophysiology of this patient's pericardial effusion?