Pulmonary Vascular Disease - USMLE Step 2

1. Which of the following is an appropriate initial oral therapy for this patient?
   Answer: Sildenafil This patient has symptomatic (WHO class III) idiopathic pulmonary arterial hypertension (PAH) and is not a candidate for calcium channel blocker therapy because her vasoreactivity test was negative. Treatment should be initiated with an advanced PAH-specific therapy. Sildenafil, a phosphodiesterase-5 inhibitor, is a standard first-line oral agent that acts as a pulmonary vasodilator. Furosemide is for symptom management of fluid overload, and warfarin's role is debated but neither is a primary PAH therapy. Diltiazem is a calcium channel blocker and would be ineffective or harmful.
2. Which of the following is the most appropriate initial treatment?
   Answer: Rivaroxaban For a hemodynamically stable patient with an acute pulmonary embolism and no significant contraindications (e.g., severe renal or hepatic disease), a direct oral anticoagulant (DOAC) such as rivaroxaban or apixaban is a first-line option and is preferred over vitamin K antagonists. Unfractionated heparin is typically reserved for patients who are hemodynamically unstable, have severe renal insufficiency, or in whom rapid reversal of anticoagulation might be necessary. Thrombolytic therapy is reserved for massive PE with hemodynamic instability. An IVC filter is indicated only if anticoagulation is contraindicated.
3. Based on the Wells' criteria for pulmonary embolism, what is the most appropriate immediate next step?
   Answer: Proceed directly to CT pulmonary angiography This patient has a high pre-test probability for pulmonary embolism (PE). Using the Wells' criteria: active cancer (+1 point), heart rate > 100/min (+1.5 points), and PE is the most likely diagnosis (+3 points). Her total score is 5.5, which places her in the 'PE likely' category (score > 4). For patients with a high clinical probability of PE, D-dimer testing is not recommended because a negative result does not reliably exclude PE. The appropriate next step is to proceed directly to definitive diagnostic imaging with CT pulmonary angiography.
4. Which of the following is the most appropriate initial test to screen for and estimate the severity of the suspected condition?
   Answer: Transthoracic echocardiogram The clinical presentation is highly suggestive of pulmonary hypertension (PH). The best initial, non-invasive test to evaluate for PH is a transthoracic echocardiogram. It can provide an estimate of the pulmonary artery systolic pressure, assess the size and function of the right ventricle, and identify other potential cardiac causes of her symptoms. While right heart catheterization is the gold standard for confirming the diagnosis, it is an invasive procedure that typically follows a screening echocardiogram.
5. These findings are most suggestive of which of the following diagnoses?
   Answer: Acute pulmonary embolism This constellation of findings is classic for acute pulmonary embolism (PE). The risk factor (recent surgery), clinical presentation (dyspnea, tachycardia), ECG findings (sinus tachycardia, new RBBB, and anterior T-wave inversions suggesting right ventricular strain), and arterial blood gas (acute respiratory alkalosis with hypoxemia indicating an increased A-a gradient) all point towards PE. While an anterior MI can cause T-wave inversions, it would not typically cause a respiratory alkalosis.
6. Which of the following is the most appropriate next step in management?
   Answer: No further diagnostic testing for pulmonary embolism is needed This patient has a very low pre-test probability for pulmonary embolism and meets all of the Pulmonary Embolism Rule-out Criteria (PERC): age <50, HR <100, SaO2 >94%, no unilateral leg swelling, no hemoptysis, no recent surgery/trauma, no prior VTE, and no hormone use. For patients who are PERC-negative, the likelihood of PE is extremely low (<2%), and no further diagnostic testing, including D-dimer, is indicated. This approach safely avoids unnecessary testing and radiation exposure.
7. Which of the following is the most appropriate next step in management?
   Answer: Initiate anticoagulation with apixaban Current guidelines recommend anticoagulation for patients with a subsegmental pulmonary embolism (SSPE) who are symptomatic (like this patient with pleuritic pain and dyspnea) or have risk factors for VTE recurrence. Withholding anticoagulation may be considered only in highly selected, asymptomatic patients with no risk factors and a low risk of recurrence. Systemic thrombolysis is not indicated for a small, hemodynamically insignificant PE. An IVC filter is not indicated as the patient can be anticoagulated.
8. Which of the following is the most reasonable next diagnostic step?
   Answer: Obtain lower extremity compression ultrasonography In this patient, CTPA is relatively contraindicated due to renal failure, and a V/Q scan is likely to be non-diagnostic due to the abnormal chest x-ray. A practical and low-risk next step is to perform lower extremity compression ultrasonography to look for a deep vein thrombosis (DVT). If a proximal DVT is found, this confirms the diagnosis of venous thromboembolism (VTE), and the patient can be treated for PE without needing further, more risky pulmonary imaging. If the ultrasound is negative, other diagnostic options would need to be considered.
9. A 50-year-old woman with prior DVT has suspected CTEPH based on V/Q mismatch and elevated PASP on echo. Meds: none. Exam: loud P2, RV heave. She asks what therapy offers potential cure rather than symptom control. Which of the following is the most appropriate next step in management?
   Answer: Refer for evaluation for pulmonary thromboendarterectomy if operable This question tests USMLE Step 2 CK skills in understanding Pulmonary Vascular Disease and its management. Pulmonary Vascular Disease includes conditions like pulmonary embolism and hypertension, requiring specific diagnostic and management strategies. In this scenario, the vignette provides clinical clues such as prior DVT and V/Q mismatches suggesting CTEPH, which suggest potential for surgical cure. Choice A is correct because it aligns with the guideline to refer for PTE evaluation in operable CTEPH. Choice B is incorrect because it fails to address the thromboembolic cause, often leading to infectious misdiagnosis. Teaching strategies include emphasizing the importance of recognizing key clinical signs of pulmonary vascular disorders and applying evidence-based management protocols. Encourage practice with differential diagnosis and appropriate test selection.
10. A 65-year-old woman has sudden dyspnea after a long flight. D-dimer is elevated. CTPA shows PE. PMH: prior GI bleed 2 weeks ago requiring transfusion. Meds: pantoprazole. She is stable but high bleeding risk. Which of the following is the most appropriate next step in management?
    Answer: Place an IVC filter because anticoagulation is temporarily contraindicated This question tests USMLE Step 2 CK skills in understanding Pulmonary Vascular Disease and its management. Pulmonary Vascular Disease includes conditions like pulmonary embolism and hypertension, requiring specific diagnostic and management strategies. In this scenario, the vignette provides clinical clues such as post-flight PE with recent GI bleed, which suggest high bleeding risk. Choice A is correct because it aligns with the guideline to place IVC filter when anticoagulation is contraindicated. Choice B is incorrect because it fails to address bleeding risk, often leading to avoidance of necessary prevention. Teaching strategies include emphasizing the importance of recognizing key clinical signs of pulmonary vascular disorders and applying evidence-based management protocols. Encourage practice with differential diagnosis and appropriate test selection.
11. A 50-year-old woman reports 2 years of worsening exercise intolerance and dyspnea. She had a proximal DVT 3 years ago and stopped anticoagulation after 3 months. PMH: DVT. Meds: none. Vitals: BP 122/76, HR 92, RR 18, SpO2 94% on room air. Exam: loud P2, right ventricular heave, mild hepatomegaly, no wheezes. ECG: right axis deviation. Echocardiogram shows right ventricular enlargement with elevated estimated pulmonary artery systolic pressure. Ventilation-perfusion scan demonstrates multiple segmental perfusion defects with preserved ventilation. What is the most likely diagnosis?
    Answer: Chronic thromboembolic pulmonary hypertension from organized thrombi This question tests USMLE Step 2 CK skills in understanding Pulmonary Vascular Disease and its management. Pulmonary Vascular Disease includes conditions like pulmonary embolism and hypertension, requiring specific diagnostic and management strategies. In this scenario, the vignette provides clinical clues such as prior DVT and mismatched V/Q defects, which suggest chronic thromboembolic pulmonary hypertension. Choice B is correct because it aligns with the guideline to diagnose CTEPH based on history and imaging mismatches. Choice A is incorrect because it fails to address the thromboembolic history, often leading to misattribution to idiopathic causes. Teaching strategies include emphasizing the importance of recognizing key clinical signs of pulmonary vascular disorders and applying evidence-based management protocols. Encourage practice with differential diagnosis and appropriate test selection.
12. A 45-year-old man has 10 months of progressive exertional dyspnea and fatigue. He has untreated obstructive sleep apnea and loud snoring; he has not used CPAP. PMH: obesity. Meds: none. Vitals: BP 134/82, HR 96, RR 18, SpO2 93% on room air. Exam: accentuated P2, parasternal heave, mild bilateral ankle edema; lungs are clear. Labs: BNP mildly elevated; CBC normal. ECG: right axis deviation. CXR: prominent central pulmonary arteries. Transthoracic echocardiogram shows estimated pulmonary artery systolic pressure 62 mm Hg with right ventricular hypertrophy and normal left ventricular systolic function. Which diagnostic test should be ordered next?
    Answer: Right heart catheterization to confirm pressures and hemodynamics This question tests USMLE Step 2 CK skills in understanding Pulmonary Vascular Disease and its management. Pulmonary Vascular Disease includes conditions like pulmonary embolism and hypertension, requiring specific diagnostic and management strategies. In this scenario, the vignette provides clinical clues such as progressive dyspnea and elevated pulmonary artery pressure on echo, which suggest pulmonary hypertension likely from OSA. Choice A is correct because it aligns with the guideline to confirm pulmonary hypertension diagnosis via right heart catheterization based on echocardiographic suspicion. Choice B is incorrect because it fails to address the chronic nature, often leading to overlooking underlying causes. Teaching strategies include emphasizing the importance of recognizing key clinical signs of pulmonary vascular disorders and applying evidence-based management protocols. Encourage practice with differential diagnosis and appropriate test selection.
13. Which of the following is the most appropriate next diagnostic step?
    Answer: CT pulmonary angiography This patient has a high clinical probability of pulmonary embolism (PE) based on the Wells criteria (recent surgery, tachycardia, clinical signs of DVT). In patients with high pre-test probability, a D-dimer assay is not useful as it has a low negative predictive value and is likely to be positive. The most appropriate next step is definitive diagnostic imaging. CT pulmonary angiography (CTPA) is the gold standard for diagnosing PE in hemodynamically stable patients and should be performed promptly. While a lower extremity ultrasound may confirm a DVT, a negative result does not rule out PE, and CTPA would still be required.
14. Which of the following is the most appropriate recommendation for long-term management?
    Answer: Continue apixaban indefinitely For a patient with a first unprovoked venous thromboembolism (VTE), such as this patient's PE, the risk of recurrence after discontinuing anticoagulation is high. Current guidelines recommend extended (indefinite) anticoagulation for these patients, provided their bleeding risk is low to moderate. Apixaban, a DOAC, is an excellent choice for extended therapy. Limiting therapy to 3 or 6 months carries a significant risk of a recurrent, potentially fatal VTE. Aspirin is significantly less effective than anticoagulation for secondary prevention of VTE.
15. This patient's clinical presentation is best classified as which of the following?
    Answer: Submassive pulmonary embolism This patient is hemodynamically stable (systolic blood pressure >90 mmHg), which rules out a massive PE. However, he has evidence of right ventricular (RV) strain, as indicated by the RV dilation/hypokinesis on echocardiogram and the elevated troponin (a marker of myocardial injury). This combination of hemodynamic stability with RV dysfunction defines a submassive (or intermediate-risk) pulmonary embolism. These patients require close monitoring as they are at risk of decompensating into a massive PE.
16. Which of the following is the most appropriate and potentially curative treatment for this patient?
    Answer: Pulmonary thromboendarterectomy Pulmonary thromboendarterectomy (PTE) is the definitive, potentially curative treatment for patients with CTEPH who have surgically accessible chronic clots in the major pulmonary arteries. This procedure involves surgically removing the organized fibrous material from the pulmonary arterial tree, which can lead to a dramatic improvement in hemodynamics and symptoms. While all CTEPH patients require lifelong anticoagulation, it is not a curative therapy. Medical therapies like vasodilators are reserved for patients who are not surgical candidates or have persistent PH after surgery. Lung transplantation is a last resort.
17. Which of the following is the most appropriate next step in management?
    Answer: Order a D-dimer assay This patient has a low pre-test probability for pulmonary embolism (PE) based on the Wells score of 1.5 (≤4 is low probability). According to diagnostic algorithms, for patients with low clinical probability of PE, the next step is to use a sensitive screening test like a D-dimer assay. A negative D-dimer result in this setting has a high negative predictive value and can effectively rule out PE, avoiding the need for radiation exposure and contrast from imaging. A positive D-dimer would then prompt further imaging.
18. Which of the following is the most appropriate next diagnostic test to evaluate for the most likely cause of his pulmonary hypertension?
    Answer: Ventilation-perfusion (V/Q) scan The patient's history of prior PE followed by the insidious onset of progressive dyspnea and signs of pulmonary hypertension (PH) is highly suggestive of chronic thromboembolic pulmonary hypertension (CTEPH). The recommended screening test of choice for CTEPH is the ventilation-perfusion (V/Q) scan. It is more sensitive than CTPA for detecting the chronic, organized, and often peripheral thrombi characteristic of CTEPH, which appear as mismatched perfusion defects. If the V/Q scan is positive, further evaluation with right heart catheterization and pulmonary angiography would follow.
19. Which of the following is the most appropriate management for this patient?
    Answer: Placement of an inferior vena cava filter This patient has an absolute contraindication to anticoagulation due to his recent hemorrhagic stroke. In such situations, the primary indication for an inferior vena cava (IVC) filter is to prevent additional thrombi from the lower extremities from embolizing to the pulmonary circulation. Any form of anticoagulation, even at lower doses, would carry an unacceptably high risk of catastrophic intracranial hemorrhage. Surgical embolectomy is an invasive procedure reserved for patients with massive PE who have failed or have contraindications to thrombolysis, not for stable patients.
20. Assuming no absolute contraindications, which of the following is the most appropriate immediate intervention?
    Answer: Administer intravenous alteplase This patient presents with a massive pulmonary embolism, which is defined by the presence of hemodynamic instability (hypotension, SBP < 90 mmHg). In the absence of absolute contraindications (e.g., active bleeding, recent hemorrhagic stroke), the treatment of choice is systemic thrombolysis with a tissue plasminogen activator like alteplase. This intervention can rapidly dissolve the clot, reduce right ventricular afterload, and improve hemodynamics. Anticoagulation with heparin alone is insufficient for a massive PE. Delaying treatment for further imaging is inappropriate in a critically ill patient.

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