Interval training 800m x 6

Again, today is my weekly interval training, 800m x 6, 3 min rest, 5:00 target pace. In my previous 800m x 6, usually I have difficulty keeping my pace consistent down to the last split. Added to the problem that the last split always hit on a 200m slightly uphill slope.

Today, I finally got one with consistent pace down to the last split.
The pace of the 6 splits are - 5:00, 4:56, 4:54, 4:59, 5:00, 4:56 respectively. Though my heart rate peak up significantly in my last split. I am not sure if I can still keep the 5:00 pace for another 2 more splits.