From VISA USA
http://usa.visa.com/business/resource_center/faq.html?it=c|/business/cards/visa_gift.html|here#anchor_15
Can the Visa Gift card be used outside of the United States?
If the card states "Valid only in the United States" on the front, the provider has issued a Domestic Use Only card. This means that the card will not be accepted at locations outside of the United States.
So if the card does not say as above, it can be used internationally.
Bank of America prepaid and gift VISA cards can be used internationally.
If you don't want to take chances, just make a trip to the nearest Banco Leon when in DR and get prepaid VISA card. each one just costs RD$50 pesos and you can put any amount on it. The card can be used internationally and recharged at any Banco Leon location or via Internet Banking.