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Difficulty: HardInterpreting Imaging Results

A 58-year-old woman is evaluated in the emergency department for sudden-onset severe dyspnea, lightheadedness, and right-sided pleuritic chest pain that began 2 hours ago. Two months ago, she underwent an uncomplicated total abdominal hysterectomy for uterine fibroids. On arrival, her temperature is 37.1°C (98.8°F), blood pressure is 108/68 mmHg, pulse is 112/min, and respirations are 24/min. Pulse oximetry shows 88% on room air. A computed tomography (CT) pulmonary angiogram reveals a large, occlusive filling defect in the main pulmonary artery extending into the right and left lobar branches. Additional review of the axial CT slices demonstrates a right ventricular to left ventricular (RV/LV) diameter ratio of 1.4, with leftward bowing of the interventricular septum, and reflux of contrast into the inferior vena cava. Immediately upon returning from the radiology suite, she becomes confused and diaphoretic; her blood pressure drops to 78/50 mmHg, and her pulse increases to 132/min. What is the most appropriate next step in patient management?

  1. Administration of systemic alteplaseAnswer
  2. B
    Transthoracic echocardiography
  3. C
    Invasive pulmonary angiography
  4. D
    Initiation of oral apixaban therapy
  5. E
    Placement of an inferior vena cava filter

Answer

Administration of systemic alteplase is the appropriate next step to rapidly relieve right ventricular outflow obstruction in this patient with massive pulmonary embolism.
This patient is presenting with a massive pulmonary embolism (PE), defined by the presence of a PE accompanied by hemodynamic instability (systolic blood pressure < 90 mmHg or a drop of > 40 mmHg). The CT imaging explicitly demonstrates pathognomonic signs of severe right ventricular strain, including an RV/LV ratio greater than 1, bowing of the interventricular septum into the left ventricle, and reflux of contrast into the inferior vena cava. When a patient with these imaging findings develops obstructive shock, immediate systemic thrombolysis (e.g., alteplase) is the standard of care. Thrombolytics accelerate clot lysis, rapidly reducing pulmonary vascular resistance and restoring right ventricular forward flow, which is life-saving in massive PE.

Step-by-Step Solution

1
Analyze the patient's initial presentation and CT imaging findings.
The CT shows a large pulmonary artery filling defect with a right ventricular to left ventricular (RV/LV) ratio > 1, leftward septal bowing, and IVC contrast reflux.
These specific imaging markers indicate severe right ventricular strain and cor pulmonale.
2
Evaluate the change in the patient's clinical status.
The patient develops profound hypotension (78/50 mmHg), confusion, and diaphoresis.
The combination of confirmed PE with acute right heart strain and new-onset hemodynamic instability establishes the diagnosis of massive (high-risk) pulmonary embolism with obstructive shock.
3
Determine the optimal immediate management for massive pulmonary embolism.
Systemic thrombolytic therapy (e.g., alteplase) is indicated.
In the absence of absolute contraindications, thrombolytics rapidly lyse the clot, reducing pulmonary vascular resistance, restoring right ventricular output, and correcting the obstructive shock.

Key Concept

Massive pulmonary embolism is characterized by hemodynamic instability and radiographic evidence of right ventricular strain (e.g., RV/LV ratio > 1, septal bowing on CT). Immediate treatment with systemic thrombolysis is indicated to prevent cardiovascular collapse.
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Interpreting Imaging Results

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