Paul Heffernan bundled home 10 minutes from time to put Kilmarnock seemingly on course for three points, but substitute Santana rose to meet Paul McGowan's cross in the dying stages of the game to earn the Jambos a share of the spoils.
Both sides finished the game with 10 men after Dieter Van Tornhout and Jamie Hamill were both given their marching orders in the second half.
There was more drama at the final whistle as tempers flared following a handshake between Kilmarnock's Dean Shiels and Hearts manager Paulo Sergio, resulting in a shoving match between a number of players.
Tensions were running high following comments from both managers in the build-up to the game and there were two bookings inside the opening minute.
Dieter van Tornhout was carded for a reckless challenge on Hamill who also picked up a yellow for his aggressive reaction.
Van Tornhout passed up a good opportunity to head the visitors in front when he failed to trouble Jamie MacDonald after connecting with James Fowler's cross, and the Hearts goalkeeper then had to be alert to deal with Heffernan's looping header a minute later.
Hearts were enjoying the bulk of the early possession without testing Cammy Bell in the home goal and their first chance came after 15 minutes when Fowler's sliced clearance looped just over his own crossbar following a dangerous delivery from Ian Black.
Garry Hay's effort from long distance sailed over as the hosts searched for an opener as both goalkeepers remained virtual spectators.
For Hearts, Stephen Elliott went agonisingly close to getting on the end of Andy Driver's cross on the half-hour mark and Rudi Skacel then forced Bell into a low stop from the edge of the box.
Lewis Toshney was booked for a careless lunge on Danny Grainger after 35 minutes, however Hearts were unable to profit from the resulting free-kick.
Marius Zaliukas should have done better when he rose to meet Black's corner but the Lithuanian defender failed to hit the target.
Both teams began the second period brightly.
Taouil's long-range effort was comfortably dealt with by Bell in the opening minute and at the other end MacDonald punched away Dean Shiels' free-kick.
The hosts were reduced to 10 men after 53 minutes when Van Tornhout received his second booking for a clumsy tackle on Hamill.
The home players vented their fury at referee Euan Norris, with Heffernan receiving a booking for dissent.
Hearts created their best chance of the match on the hour mark, as Hmmill swung over a pin-point cross but Elliott's header drifted inches wide.
Hearts manager Sergio made his first change of the match when he replaced Grainger with Ryan McGowan, in an attempt to make his side's one-man advantage count.
After 72 minutes Hearts introduced Santana in place of Driver as they continued to look the more threatening of the two sides without really threatening Bell's goal.
Kilmarnock had an attempt of their own to grab an opener and Andy Webster did well to block Shiels' fizzing shot.
The home side grabbed the opening goal from the resulting corner. Toshney rose to meet Shiels' cross and despite an excellent block on the line Heffernan bundled the ball into the net.
Referee Norris showed his second red card of the game when Hamill was ordered off for a second booking.
The former Kilmarnock defender lunged in on Hay leaving Norris with little option but to produce a red.
Hay fired wide of goal in the final minute as Kilmarnock looked to comfortably hold on for victory.
Hearts were not finished though and McGowan's perfect cross was turned in by Santana to ensure a share of the points.