An ablation instrument for applying ablative energy to epicardial tissue via a subxiphoid access surgical approach to treat cardiac arrhythmia, the ablation instrument comprising: head assembly sized and shaped for a subxiphoid surgical approach to a patient's heart, the head assembly defining a contact face and including: a paddle body defining an outer perimeter of the head assembly, a first elongated ablation electrode, a second elongated ablation electrode, wherein the first and second ablation electrodes are coupled to the paddle body in a spaced apart, electrically isolated fashion such that a spatial relationship between the first and second ablation electrodes is fixed, the ablation electrodes being exteriorly exposed at the contact face and entirely within the outer perimeter; a tubular member extending from the head assembly; and wiring electrically connected to the first and second ablation electrodes for delivering energy to the first and second ablation electrodes, the wiring extending through the tubular member; wherein the instrument is manipulable to locate the contact face on epicardial tissue of a patient's heart via a subxiphoid surgical approach, wherein the paddle body includes: a head; a first skirt projecting from the head and surrounding a perimeter of the first ablation electrode to define a first suction region; a second skirt projecting from the head and surrounding a perimeter of the second ablation electrode to establish a second suction region; a first suction aperture formed by the head within the first suction region for applying a suction force to the first suction region; and a second suction aperture formed by the head within the second suction region for applying a suction force to the second suction region. head assembly sized and shaped for a subxiphoid surgical approach to a patient's heart, the head assembly defining a contact face and including: a paddle body defining an outer perimeter of the head assembly, a first elongated ablation electrode, a second elongated ablation electrode, wherein the first and second ablation electrodes are coupled to the paddle body in a spaced apart, electrically isolated fashion such that a spatial relationship between the first and second ablation electrodes is fixed, the ablation electrodes being exteriorly exposed at the contact face and entirely within the outer perimeter; a paddle body defining an outer perimeter of the head assembly, a first elongated ablation electrode, a second elongated ablation electrode, wherein the first and second ablation electrodes are coupled to the paddle body in a spaced apart, electrically isolated fashion such that a spatial relationship between the first and second ablation electrodes is fixed, the ablation electrodes being exteriorly exposed at the contact face and entirely within the outer perimeter; a tubular member extending from the head assembly; and wiring electrically connected to the first and second ablation electrodes for delivering energy to the first and second ablation electrodes, the wiring extending through the tubular member; wherein the instrument is manipulable to locate the contact face on epicardial tissue of a patient's heart via a subxiphoid surgical approach, a head; a first skirt projecting from the head and surrounding a perimeter of the first ablation electrode to define a first suction region; a second skirt projecting from the head and surrounding a perimeter of the second ablation electrode to establish a second suction region; a first suction aperture formed by the head within the first suction region for applying a suction force to the first suction region; and a second suction aperture formed by the head within the second suction region for applying a suction force to the second suction region.