Blood pressure is governed by five elements--the strength of the heartbeat, the volume of blood, the viscosity of the blood, the resistance of the arterioles, and the elasticity of the arterial walls. An abnormality of any of these can cause the blood pressure to be too high or too low.
Depending on the complexity of the case a trial can last anywhere from one day to six months or longer. If you are asking how long a rape prosecution takes you are probably looking at 6 months to a couple of years.
The length of a trial will vary depending upon the complexity of the case, the number of witnesses. Jury trials generally take at least three days to complete, and can go as long as many months. The average length of a trial is probably between four to five days.