The heart of a giraffe is not smaller than 60 cm. and weigh 11 kg. The distance between it and the brain is 2-3 meters(for example in people it is only 20-30 cm.).
The blood system of the giraffe is precise. It pumps the unnecessary blood, when the head is down on the ground and prevents the blood to return again in the heart of the giraffe when it move his head up.