Apparatus and method for cardiac ablation

An apparatus for performing cardiac ablation includes an applicator such as a catheter 14 with multiple electrodes 16 to supply an electrical potential across cells within an area of tissue; and a controller to deliver a voltage waveform. Preferably the electrodes are annular and are distributed along the length of the catheter. The catheter may also have a sensor electrode 22 operable to detect signals from the sinoatrial node of the heart when the apparatus is used to treat cardiac arrhythmia. The controller may provide a biphasic, truncated waveform having leading edges a2 which are of greater magnitude than trailing edges b2, i.e. the waveform has a tilt. A user interface (28, figure 2) may be used to define the shape of the waveform provided by a waveform generator (18). In use the catheter may be located within the left atrium of the heart in order to form a linear lesion by electroporation or the rupturing of cells.