This unusual spiral galaxy most likely got its somewhat unusual structure through tidal interactions between it and another neighboring galaxy. Both most likely belong to the Hickson 44 group. All are located some 60 million light-years away (in the direction of the Leo constellation).
This particular member, known as NGC 3190, is seen here almost edge-on, which allows astronomers to make out the asymmetric spiral arms with clarity. As you can see, this effect is most clear near the central region of the galaxy (it's also easy to see the slight warping near the galactic disk).
NGC 3190 spans some 75,000 light-years across. If you look closely, some other background galaxies are visible as well.
See a larger image here.