Abstract. Background

No abstract

Open irrigation (Irrig) cools the electrode and electrode-tissue interface (ETI), preventing thrombus. Improving electrode temperature (ET) feedback by insulating the Irrig electrode internally may help prevent excessive tissue heating. The purpose was to compare an insulated Irrig electrode to a conventional Irrig electrode in ET response and lesion formation using a canine thigh muscle preparation. Methods In 11 dogs, the skin over the thigh muscle was incised and raised to form a cradle which was superfused with heparinized blood at 37°C. The 7F insulated catheter has 6 Irrig holes proximal to a 2.5mm tip electrode (spray around electrode and ETI) and one thermally insulated Irrig channel through the electrode (only external cooling, Ext Cool, St Jude Medical). The Ext Cool and a conventional 7F, 2.5mm open Irrig catheter (external and internal electrode cooling, Ext/Int Cool, St Jude Medical) were held perpendicular or parallel to thigh muscle. RF was applied for 60 sec (n=176) at 10, 15, 20, or 25W with saline Irrig at 17ml/min in low blood flow (<0.1 m/sec) to favor thrombus. ET, ETI and tissue temperatures (3 and 7mm depths) were measured. After each RF, blood was removed to examine for thrombus. Results Table and Fig Conclusions Ext Cool had: greater correlation between ET and both lesion depth (r=0.84 vs 0.54) and steam pop (ET≥51°C vs ET 32– 48°C); lower ETI temperature and less thrombus.