Aortic and Pulmonary Root Aneurysms in a Child With Loeys-Dietz Syndrome

Frail Silk: Is the Hughes-Stovin Syndrome a Behçet Syndrome Subtype with Aneurysm-Involved Gene Variants?

Hughes-Stovin syndrome is a rare disease characterized by thrombophlebitis and multiple pulmonary and/or bronchial aneurysms. The etiology and pathogenesis of HSS are incompletely known. The current consensus is that vasculitis underlies the pathogenic process, and pulmonary thrombosis follows arterial wall inflammation. As such, Hughes-Stovin syndrome may belong to the vascular cluster with lung involvement of Behçet syndrome, although oral aphtae, arthritis, and uveitis are rarely found. Behçet syndrome is a multifactorial polygenic disease with genetic, epigenetic, environmental, and mostly immunological contributors. The different Behçet syndrome phenotypes are presumably based upon different genetic determinants involving more than one pathogenic pathway. Hughes-Stovin syndrome may have common pathways with fibromuscular dysplasias and other diseases evolving with vascular aneurysms. We describe a Hughes-Stovin syndrome case fulfilling the Behçet syndrome criteria. A MYLK variant of unknown significance was detected, along with other heterozygous mutations in genes that may impact angiogenesis pathways. We discuss the possible involvement of these genetic findings, as well as other potential common determinants of Behçet/Hughes-Stovin syndrome and aneurysms in vascular Behçet syndrome. Recent advances in diagnostic techniques, including genetic testing, could help diagnose a specific Behçet syndrome subtype and other associated conditions to personalize the disease management.

Surgical treatment of Loeys-Dietz syndrome in a 3-year-old: case report and review of literature

Aortic complications of Loeys-Dietz syndrome (LDS) rarely present in children. Here we describe a case of LDS type 2 in a 3-year-old child with severe aortic root dilation and severe aortic regurgitation. A Bentall procedure combined with a Cabrol-type coronary modification was used to treat this child. In order to minimize the need for reintervention as the child grows. We chose a composite valve-graft by a St Jude Regent 21# mechanical valve seated within a 24 mm Gore-Tex graft to finish the Bentall procedure. Echocardiographic studies demonstrated good valve and ventricular function at 1-year follow-up. This child is one of the youngest LDS patients to receive a Bentall procedure and the way using a composite valve-graft to finish the operation can provide a reference for the surgical strategies of such patients in the future. Children with LDS and severe aortic annulus dilatation combined with severe aortic valve regurgitation require early surgical intervention, and implantation of a mechanical valved-conduit can be utilized successfully. Life-long follow-up of the valved-conduit and arterial vessels of these patients is necessary. The experience gained from this case contributes to the management of the rare LDS patient who presents at an early age with aortic root and valve pathology. Close monitoring and early intervention are important.

Potential Molecular Pathways Related to Pulmonary Artery Aneurysm Development: Lessons to Learn from the Aorta

Pulmonary arterial hypertension (PAH) is a rare disease caused by pulmonary vascular remodeling. Current vasodilator treatments have substantially improved patients’ survival. This improved survival has led to the appearance of complications related to conditions previously underdiagnosed or even ignored, such as pulmonary artery aneurysm (PAA). The presence of a dilated pulmonary artery has been shown to be related to an increased risk of sudden cardiac death among PAH patients. This increased risk could be associated to the development of left main coronary artery compression or pulmonary artery dissection. Nevertheless, very little is currently known about the molecular mechanisms related to PAA. Thoracic aortic aneurysm (TAA) is a well-known condition with an increased risk of sudden death caused by acute aortic dissection. TAA may be secondary to chronic exposure to classic cardiovascular risk factors. In addition, a number of genetic variants have been shown to be related to a marked risk of TAA and dissection as part of multisystemic syndromes or isolated familial TAA. The molecular pathways implied in the development of TAA have been widely studied and described. Many of these molecular pathways are involved in the pathogenesis of PAH and could be involved in PAA. This review aims to describe all these common pathways to open new research lines that could help lead to a better understanding of the pathophysiology of PAH and PAA and their clinical implications.