**Core Concept**
Buerger's disease, also known as thromboangiitis obliterans, is a rare, non-atherosclerotic, inflammatory, and occlusive vascular disease primarily affecting the small and medium-sized arteries and veins of the limbs. It is characterized by recurring episodes of vasculitis, thrombosis, and inflammation, leading to ischemia and tissue damage.

**Why the Correct Answer is Right**
Xanthinol nicotinate, a vasodilator, is used to manage Buerger's disease by improving blood flow to the affected limbs. It acts by relaxing the smooth muscle cells of the blood vessels, thereby increasing their diameter and promoting vasodilation. This helps to alleviate the symptoms of ischemia and pain associated with Buerger's disease. Xanthinol nicotinate also has anti-inflammatory properties, which may contribute to its therapeutic effects in this condition.

**Why Each Wrong Option is Incorrect**
**Option B:** Propranolol is a beta-blocker, which would actually worsen the symptoms of Buerger's disease by reducing blood flow to the affected limbs. Beta-blockers are generally contraindicated in patients with peripheral vascular disease.

**Option C:** Calcium channel blockers (CCBs) may also worsen the symptoms of Buerger's disease by causing vasodilation, which can lead to a decrease in blood pressure and a reduction in blood flow to the affected limbs.

**Option D:** This option is incorrect because not all of the above options are used to treat Buerger's disease.

**Clinical Pearl / High-Yield Fact**
Xanthinol nicotinate is a vasodilator that should be used cautiously in patients with Buerger's disease, as it may worsen symptoms if not used correctly. A thorough medical evaluation and monitoring are essential to ensure the safe and effective use of this medication.

**✓ Correct Answer: A. Xanthinol nicotinate**