Surgical Removal of a Pacemaker Lead Entrapped by a Chiari Network: A Case Report

The Chiari network, one of the remnants of the right valve of the sinus venosus, is considered clinically insignificant in most cases but attention should be paid since this embryological remnant can be a potential risk for complications during procedures. We report a case of atrioventricular block in which a pacemaker lead was entrapped by a Chiari network. A 78-year-old woman underwent dual-chamber pacemaker implantation for symptomatic 2:1 atrioventricular block. A tined J-shaped atrial lead was placed at the right atrial appendage, which later became dislodged to a lower position and entrapped. After multiple unsuccessful attempts to withdraw the lead, surgical removal was performed. The lead was strictly entangled within the fibrous threads of the Chiari network that was not detected by transthoracic echocardiography before and during the implantation.