Differential Diagnosis

The patient presents with a complex set of symptoms and lab results, including an elevated D-dimer, occlusive thrombus on the left leg, moderate plural effusion, elevated BNP, and atrial fibrillation with rapid ventricular response (RVR). Here's a differential diagnosis organized into the requested categories:

• Single Most Likely Diagnosis

  • Pulmonary Embolism (PE): The combination of an elevated D-dimer, occlusive thrombus on the left leg (suggesting deep vein thrombosis, DVT), and moderate plural effusion, along with atrial fibrillation and elevated BNP, strongly suggests a pulmonary embolism. The presence of DVT and PE would explain the elevated D-dimer and the plural effusion could be due to the increased pressure and strain on the heart.

• Other Likely Diagnoses

  • Heart Failure: Elevated BNP and moderate plural effusion could indicate heart failure, especially with the context of atrial fibrillation with RVR, which can lead to decreased cardiac output and increased pressures.
  • Cardiomyopathy: The elevated BNP and the presence of atrial fibrillation with RVR could suggest an underlying cardiomyopathy, which might be contributing to the heart's inability to efficiently pump blood.

• Do Not Miss Diagnoses

  • Dissecting Aortic Aneurysm: Although less likely given the specific findings, a dissecting aortic aneurysm could present with acute onset of symptoms, including chest pain, shortness of breath, and could potentially lead to a plural effusion. It's critical to consider this diagnosis due to its high mortality rate if missed.
  • Cardiac Tamponade: The presence of a moderate plural effusion and elevated BNP could, in a different context, suggest cardiac tamponade, especially if there were signs of obstructive shock. This is a life-threatening condition that requires immediate intervention.

• Rare Diagnoses

  • Thromboembolic Events in Other Locations: While less likely, given the DVT and suspected PE, it's possible to consider thromboembolic events in other locations, such as the brain or mesenteric vessels, though these would likely present with different symptoms.
  • Pulmonary Arterial Hypertension (PAH): This could be a contributing factor to the elevated BNP and plural effusion, especially in the context of atrial fibrillation, but would typically require more specific diagnostic testing to confirm.

Each of these diagnoses requires careful consideration of the patient's symptoms, laboratory results, and imaging studies to determine the most appropriate management plan.