One division of the Akshavedamsha spans 40 minutes of arc, two thirds of a degree, forty five to a sign and 540 in the zodiac. The ascendant crosses that arc in about two minutes and forty seconds.
Only the D-60 is finer. At this scale the ascendant is a function of the seconds of the birth time, and no ordinary record carries seconds, so the honest position is that the D-45 ascendant is unavailable for almost every chart an astrologer will ever be handed. Saying so is more useful than producing one.
The planetary placements hold up better, as they do in every high varga. The Moon crosses 40 minutes of arc in about an hour and thirteen minutes, the Sun in about sixteen hours, and the rest of the grahas move too slowly for a day of uncertainty to matter.
The Akshavedamsha belongs only to the shodashavarga. Its subject is character and conduct, and the tradition associates it with the paternal line, making it the counterpart of the D-40 and its maternal one.
There is a further consequence of the fineness. A varga this narrow amplifies any error in the underlying longitudes as well as in the time, so a chart cast against a different ayanamsha will differ throughout the D-45 even where the D-1 is identical.