Differential Diagnosis

The patient presents with significant shortness of breath, lightheadedness, palpitations, and a sensation of fullness in her chest, alongside a history of metastatic breast cancer and current chemotherapy. The clinical findings and history guide the differential diagnosis into the following categories:

• Single Most Likely Diagnosis

  • Cardiac Tamponade: The patient's symptoms of shortness of breath, lightheadedness, palpitations, and chest fullness, combined with physical examination findings of diminished heart sounds, jugular venous distention, and cool extremities, are highly suggestive of cardiac tamponade. The low-voltage electrocardiogram and enlarged cardiac silhouette on chest x-ray further support this diagnosis, as they can indicate fluid accumulation in the pericardial space, which is consistent with tamponade, especially in a patient with metastatic cancer.

• Other Likely Diagnoses

  • Pulmonary Embolism: Although the lungs are clear on physical examination, the patient's symptoms of shortness of breath and the use of Apixaban for deep venous thrombosis prophylaxis suggest that pulmonary embolism should be considered, especially given the patient's cancer history which increases the risk of thromboembolic events.
  • Congestive Heart Failure: The patient's symptoms and the use of furosemide for edema could suggest heart failure, but the absence of lung congestion on physical examination and the specific findings suggestive of tamponade make this less likely.
  • Pericarditis: Could be considered due to the patient's cancer and chemotherapy, but the clinical presentation and findings are more indicative of tamponade.

• Do Not Miss Diagnoses

  • Massive Pulmonary Embolism: Although less likely given the clear lungs, a massive pulmonary embolism could present with similar symptoms and would be catastrophic if missed.
  • Septic Shock: The patient's fever and hypotension could suggest sepsis, which would require immediate antibiotic therapy and fluid resuscitation.
  • Hemorrhagic Cardiac Tamponade: Especially in the context of anticoagulation with Apixaban, a hemorrhagic tamponade could rapidly progress and would necessitate immediate intervention.

• Rare Diagnoses

  • Constrictive Pericarditis: Could present with similar symptoms but is less likely given the acute presentation and the patient's history.
  • Restrictive Cardiomyopathy: Although possible, the clinical findings and the patient's history make this a less likely diagnosis compared to tamponade.