Chiari network: a protective filter against pulmonary embolism in a case of polycythaemia

Abstract

The Chiari network, a net-like structure within the right atrium, has been described as an embryonic remnant of no clinical significance. Its role in facilitating paradoxical arterial embolic events and as a potential site for thrombus formation however, has been reported in the literature. This case illustrates the protective filter-effect of the Chiari network in a 79-year-old Caucasian man with an unknown diagnosis of polycythaemia rubra vera who presented with clinical signs and symptoms of deep vein thrombosis. Transoesophageal echocardiogram confirmed entrapment of a thrombus within the Chiari network, which was not visualised following treatment on repeat scanning 1 month later. Here the authors describe how the Chiari network may have prevented the occurrence of a fatal massive pulmonary embolism in a patient with a high pro-thrombotic tendency, and review the current literature regarding the action of this anatomic variant as risk factor or protector.

A case of large Chiari network mimicking right atrial thrombus

“…It may act as a nidus for thrombus formation as well as a protective filter against pulmonary embolism. Obaji et al reported that the Chiari network may play a protective role such as inferior vena cava filter in the case of polycythemia [ 4 ]. However, Schneider et al emphasized significantly higher prevalence rates for patent foramen ovale in patients with a Chiari network and an association with a serious risk for arterial embolism [ 5 ].…”

Accidental Entrapment of Electrical Mapping Catheter by Chiari’s Network in Right Atrium during Catheter Ablation Procedure

“…The prevalence of Chiari's network is reported to be approximately 2% with estimates varying from 1.3 to 4% in postmortem findings and 0.3 to 9.5% in TTE findings [ 1 ]. The previously reported clinical complications associated with Chiari's network are the intra-RA thrombus formation [ 3 ] as well as the entrapment of thromboemboli [ 4 ], atrial tachyarrhythmia [ 5 ], and device entrapment [ 6 – 12 ]. To date, 9 cases of device entrapment with Chiari's network have been reported.…”

Chiari Network in Right Atrium of Heart

“…8,9 Still in debate, chiari network may have a protective role in preventing embolization by holding thrombus in the network in some patients with Thrombophilia. 10 …”