Which of the following is a type of ablation for atrial fibrillation?

Segmental ostial pulmonary vein isolation is recognized as a type of ablation for atrial fibrillation because it specifically targets the electrical pathways that cause the arrhythmia. This procedure involves isolating or blocking specific areas of the heart—particularly the pulmonary veins that enter the left atrium—where abnormal electrical signals that initiate atrial fibrillation often originate.

By creating scar tissue through the ablation process, the abnormal signals can be disrupted, leading to a reduction in episodes of atrial fibrillation or even a potential cure in some patients. This method is a key part of catheter ablation techniques, which are widely employed for managing atrial fibrillation when medications are ineffective or not well-tolerated.

In contrast, the other options listed, such as ventricular pacing, cardiac defibrillation, and pacemaker implantation, are not categorized as ablation techniques. Instead, ventricular pacing and pacemaker implantation are designed to manage heart rhythm and support the heart's function, while cardiac defibrillation is used to restore normal rhythm during life-threatening arrhythmias, none of which address the root causes of atrial fibrillation like ablation does.