Final answer:
Beta blockers are used as first-line treatment in aortic dissection until surgery can be performed to reduce blood pressure and heart rate and relieve stress on the aortic walls.
Step-by-step explanation:
Beta blockers are commonly used as first-line treatment in aortic dissection until surgery can be performed because they help to reduce blood pressure and heart rate, which can relieve the stress on the aortic walls and reduce the risk of further tearing or rupture. By blocking the β-receptors associated with vasoconstriction and cardioacceleration, beta blockers help to dilate blood vessels and decrease the force of contraction of the heart, therefore reducing the sheer stress on the weakened aortic wall.