Chiari network

Chiari network

Chiari network is a vestigial structure and is seen as strand like structures within the right atrial cavity on echocardiography. It is an embryonic remnant of the right valve of the sinus venosus. Chiari network is often associated with a patent foramen ovale (PFO). Hence it may be noted in cases of paradoxical embolism and stroke.

It was described by Hans Chiari in 1897 in thirteen human right atria. It was a pathological description [1, 2]. It could be misinterpreted as right atrial thrombi, tumour or vegetation. Rare case of tricuspid regurgitation due to the attachment of the network has also been described [3].

Occasionally infective endocarditis may be associated with the network [4]. Sometimes a thrombus may be caught in the network, preventing pulmonary embolism like an inferior vena caval filter! Pacemaker leads, especially the tined ones, can get entrapped in the network during implantation. Similar way, guidewire entrapment has also been described during invasive procedures [1].

In an autopsy series, Kunwar P Bhatnagar, G S Nettleton, Ferrell R Campbell, Charles E Wagner, Nobuyuki Kuwabara and Horia Muresian noted Chiari malformations in 13.6% of the 213 cadaver hearts [5], though the often quoted prevalence is around 2%.

References

1. A K M Monwarul Islam, Lima Asrin Sayami, Shahana Zaman. Chiari Network: A Case Report and Brief Overview. J Saudi Heart Assoc
   . 2013 Jul;25(3):225-9.
2. Chiari H. Ueber Netzbildungen im rechten Vorhofedes Herzens. Beitr Pathol Anat. 1897;22:1–10.
3. Jen-Ping Chang. Tricuspid Regurgitation as a Result of Chiari Network Attachment. J Thorac Cardiovasc Surg. 2012 Jan;143(1):235.
4. Darrin M Payne, Roger J F Baskett, Gregory M Hirsch. Infectious Endocarditis of a Chiari Network. Ann Thorac Surg. 2003 Oct;76(4):1303-5.
5. Kunwar P Bhatnagar, G S Nettleton, Ferrell R Campbell, Charles E Wagner, Nobuyuki Kuwabara, Horia Muresian. Chiari Anomalies in the Human Right Atrium. Clin Anat. 2006 Sep;19(6):510-6.