Pulmonary vascular disease and optical coherence tomography imaging in patients with Fontan palliation

ABSTRACT

Introduction

The Fontan procedure is the palliative procedure of choice for patients with single ventricle physiology. Pulmonary vascular disease (PVD) is an important contributor to Fontan circulatory failure.

Areas covered

We review the pathophysiology of PVD in patients with Fontan palliation and share our initial experience with optical coherence tomography (OCT) in supplementing standard hemodynamics in characterizing Fontan-associated PVD. In the absence of a sub-pulmonary ventricle, low pulmonary vascular resistance (PVR; ≤2 WU/m²) is required to sustain optimal pulmonary blood flow. PVD is associated with adverse pulmonary artery (PA) remodeling resulting from the non-pulsatile low-shear low-flow circulation. Predisposing factors to PVD include impaired PA growth, endothelial dysfunction, hypercoagulable state, and increased ventricular end-diastolic pressure. OCT parameters that show promise in characterizing Fontan-associated PVD include the PA intima-to-media ratio and wall area ratio (i.e. difference between the whole-vessel area and the luminal area divided by the whole-vessel area).

Expert opinion

OCT carries potential in characterizing PVD in patients with Fontan palliation. PA remodeling is marked by intimal hyperplasia, with medial regression. Further studies are required to determine the role of OCT in informing management decisions and assessing therapeutic responses.

KEYWORDS:

• Fontan circulatory failure
• hemodynamic assessment
• pulmonary artery remodeling
• pulmonary vascular disease
• optical coherence tomography

Article highlights

• Pulmonary vascular disease (PVD) contributes to Fontan circulatory failure. Predisposing factors include inadequate growth of the pulmonary arteries (PA), endothelial dysfunction, hypercoagulable state, and increased ventricular filling pressure.

• PVD is associated with adverse PA remodeling, reflecting long-standing non-pulsatile low shear flow. The pathophysiological process appears to be characterized by intima hyperplasia and regression of vascular smooth muscle cells.

• Optical coherence tomography (OCT) in the PA carries the potential to provide complementary information to standard hemodynamic assessment in characterizing PVD in patients with Fontan palliation.

• Promising OCT parameters in assessing PVD in the Fontan circulation include intima/media and wall area ratios.

• Future studies are required to determine the clinical utility of OCT in Fontan patients (intima/media and wall area ratios measures) in informing management strategies in patients with Fontan palliation, such as pulmonary hypertension therapy and anticoagulation.

Declarations of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

Paul Khairy is supported by the André Chagnon research chair in electrophysiology and congenital heart disease. Jean-Claude Tardif is supported by the Canada Research Chair in personalized medicine. Marie-A Chaix is supported by a ‘Fonds de recherche du Québec – Santé (FRQS)’ Junior 1 clinician-scientist award. This research was supported by Marie-A Chaix’s research funding.