Coolflow irrigation pump

Swine skeletal muscle (loin) was obtained from a butcher shop. A motor drive moving platform was created for an in vitro model simulating the beating heart. A ThermoCool SmartTouch catheter (Biosense Webster Inc., CA, USA) was placed on the tissue specimen over a vibrating platform placed within a tank filled with physiologic saline solution at 36.5°C (Fig. 1). The platform was continuously vibrated at a rate of 50 cycles per minute by an electronic motor. An RF generator (Stockert GmbH, Freiburg, Germany) was connected to deliver an RF current of 550 kHz between the catheter-tip electrode and a ground plate in the tank. A calibrated roller pump (CoolFlow irrigation pump, Biosense Webster Inc., CA, USA) connected to the irrigation port of the catheter delivered normal saline solution at a rate of 17 mL/min for ablation power below 30 W and 30 mL/min for ablation power above 30 W. The CARTO 3 system (Biosense Webster Inc., CA) used for the CF data is fully integrated into the system display and can be configured to show the data at several locations on the screen.

The patients were placed under sedation and local anesthesia for the procedure, which was performed under the guidance of TTE (iE33, Philips Medical System, Netherlands). A retrograde transaortic approach was adopted for septal hypertrophy ablation in all patients. A 4-mm irrigated-tip ablation catheter (CoolFlow Irrigation Pump, Biosense Webster, California), with the flow speed of 30 mL/min was used in the ERFA procedure. In order to reduce LVOT obstruction, each lesions were ablated for 60–120 s, with a power setting of 40–60 W. The radiofrequency energy was delivered strictly to the most proximal parts of the septum in the immediate vicinity of the LVOT. To obviate complete heart block, the tip of the ablation catheter was navigated away from the His bundle region as far as possible. Real-time TTE imaging was used to monitor the catheter location and its stable contact with the left ventricular (LV) septum (Figure 1).
ERFA was delivered to each site for 60–180 seconds with a power setting of 40–60 W. To maintain an activated clotting time of 300–350 seconds during the procedure, patients also received adjusted doses of heparin. LVOT gradients were measured by TTE at baseline and after the procedure.
A gradient reduction of >50% was regarded as the endpoint for ERFA.