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CTEPH Pathophysiology

CTEPH is the result of a single PE or recurrent pulmonary emboli arising from sites of venous thrombosis.6

According to the widely held “embolic hypothesis,”10 these PE result in endothelialized residua that obstruct or significantly narrow pulmonary arteries.

  • The reduced bioavailability of endogenous vasodilators, like nitric oxide, may contribute to endothelial dysfunction.11
  • The development of distal, small-vessel arteriopathy may also contribute to PH and right ventricular overload.
    • Small vessel arteriopathy is characterized by medial hypertrophy, intimal proliferation and thickening, microthrombi formation, and plexiform lesions.1
    • The pathogenesis of this arteriopathy remains unclear.6
  • Previous venous thromboembolic disease has also been linked to development of CTEPH.12

With CTEPH, if you know what you’re looking for, it’s relatively easy to spot. If you’re not looking for it, it’s easy to miss.3

Features of pulmonary vasculature in CTEPH1:

  • CTEPH results from persistent macrovascular obstruction and a vasoconstrictor response that lead to a secondary small-vessel arteriopathy
  • Reductions in the pulmonary-artery diameter due to thrombosis and vasoconstriction result in adverse vascular remodeling

Multiple mechanisms of small-vessel disease are operative in CTEPH.13

Microvascular disease in CTEPH may adversely impact selection for pulmonary thromboendarterectomy surgery or may affect surgical outcomes.13

  • Can a patient who recovers from an acute pulmonary embolism develop CTEPH? Find out in this video.

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CTEPH is not pulmonary arterial hypertension (PAH).

Distinguishing CTEPH from PAH (WHO Group 1 pulmonary hypertension) is essential:

  • CTEPH is caused by macrovascular obstructions in the pulmonary arteries.1
  • In appropriate surgical candidates, such obstructions can be removed via pulmonary thromboendarterectomy* (PTE) surgery.
  • PTE surgery is the first-line recommended treatment for CTEPH, and it is potentially curative.3
  • PAH is not caused by macrovascular obstructions, and PTE surgery is not indicated for PAH.
  • Though there is no cure for PAH, it can be effectively managed with medical therapies.
  • It is important to distinguish CTEPH from PAH and other types of pulmonary hypertension, because CTEPH is the only potentially curable form of pulmonary hypertension.
  • The screening tool of choice for CTEPH is ventilation/perfusion (V/Q) scanning.3
  • All patients in whom pulmonary hypertension is suspected should have a V/Q scan to exclude CTEPH.3
  • Patients who are already diagnosed with other forms of pulmonary hypertension but who have not had a V/Q scan should get one to exclude CTEPH.3

*Also called pulmonary endarterectomy or PEA.

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CTEPH can be a serious complication of pulmonary embolism.

The Pathophysiology of CTEPH


Victor F. Tapson, MD, of Cedars-Sinai Medical Center, Los Angeles, looks at how CTEPH develops, how it manifests, and several important considerations in distinguishing CTEPH from PAH.

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