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.
Without knowing a lot more about the case, it is not possible to know how long the actual trial will take. Generally after a defendant pleads not guilty, the case is set for a pretrial date that usually occurs between 30 and 60 days from the Omnibus hearing in Minnesota.