Contemporary interpretations of revered operatic works are not often music to the ears of purists. But the folks behind Heartbeat Opera in New York insist that alterations are needed to overcome dated elements. Heartbeat is presenting a spring festival with two main offerings - Butterfly (with Mackenzie Whitney and Banlingyu Ban), a revamp of Italian composer Giacomo Puccini's Madama Butterfly that is trimmed to about 100 minutes; and French composer Georges Bizet's Carmen, shortened to 90 minutes.