Thank you, Jesse Platt, for walking us through the complicated case of a 66 year old man with months of worsening dyspnea and hypoxia of unclear origin who was diagnosed with (very) severe pulmonary hypertension, and is thought to have either PVOD or pulmonary capillary hemangiomatosis (PCH)!

We went through the classification of pulmonary hypertension:

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Simonneau et al. JACC 2013.

Suggested approach to etiologic workup of PH

  1. Physical exam (look for clubbing, parasternal heave, S2, crackles on lung exam, signs of cirrhosis, etc)
  2. Chest X-ray (look for venous congestion, prominent PA, ILD)
  3. CT chest (looking for ILD, parenchymal lung disease, nodules, mosaic attenuation (what is that?) which may suggest areas of heterogenous blood flow or air trapping)
  4. Transthoracic echo (with bubble/contrast): looking for intracardiac (early bubbles) or intrapulmonary (late bubbles), estimate of RV and PA pressures, signs of RV dilation or volume/pressure overload
  5. Ventilation/perfusion (V/Q) scan: this is the gold standard for ruling out CTEPH. Remember that CTEPH doesn’t require a history of repeated PEs; it really represents a dysregulated healing response to vasoactive cytokines from even a single PE in the past!
  6. Consider PFTs and nocturnal polysomnography (to rule out OSA)
  7. Consider ABG (to confirm hypoxia, and also if concern for shunt physiology)
  8. Consider blood testing for other causes of PH (HIV, ANA [only send dsDNA, RNP if ANA+ ), RF, ANCA)
  9. Right heart catheterization: gold standard for diagnosing/confirming PH (defined as a mean PA pressure >25mm Hg)

Ultimately, this patient’s testing (RHC w/ severe pHTN, TTE w/ LVEF 60% but moderate RV dilation and late bubbles suggestive of pulmonary AVMs, CT chest w/ scattered basilar nodules with diffuse mosaic attenuation) suggested a diagnosis of PVOD vs PCH as the diagnosis.

In brief, PVOD is characterized by smooth muscle hypertrophy within pulmonary veins and venules, whereas PCH is marked by atypical capillary proliferation; both cause pulmonary hypertension, and can be difficult to differentiate from PH of other causes.

We learned that severe hypoxia (10L O2 in this case) is uncommon with most causes of PH, and should make you think of:

  2. CTEPH
  3. Large intracardiac/intrapulmonary shunt

See this table to see a comparison of PH, PVOD and PH:

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Chaisson 2016

Two final pearls

  1. PVOD and PCH patients are at a higher risk of pulmonary edema with vasodilator therapy given their capillary hemodynamics
  2. PASPs from echos are derived from the maximum tricuspid valve velocity; but this is reliant on good views on echo, and varies based on underlying comorbidities, etc. Generally TTE PASPs are thought to be off from RHC PASPs by about 10mm Hg (want more info?)
  3. There are case reports of PCH being treated with doxycycline, which apparently has anti-angiogenic properties! (see #1 below)


  1. Ginns et al. Pulmonary Capillary Hemangiomatosis With Atypical Endotheliomatosis: Successful Antiangiogenic Therapy With Doxycycline. Chest 2003.
  2. Chaisson et al. Pulmonary Capillary Hemangiomatosis and Pulmonary Veno-occlusive Disease. Clinics in Chest Medicine 2016.
  3. Simonneau et al. Updated clinical classification of pulmonary hypertension. JACC 2013.