Possible expansion of blood vessels by means of the electrostrictive effect

In cases when it is desirable to transport medication through blood vessels, especially when dealing with brain cancer being confronted with the narrow arteries in the brain, the blood-brain barrier makes the medical treatment difficult. There is a need of expanding the diameters of the arteries in order to facilitate the transport of medicaments. Recent research has pointed to various ways to improve this situation; in particular, the use ultrasound acting on microbubbles in the blood stream has turned out to be a promising option. Here, a different possibility of enlarging the diameters of arteries is discussed, namely to exploit the electrostrictive pressure produced by internal strong, ultrashort and repetitive laser pulses. Each pulse will at first give rise to inward directed optical forces, and once the pulse terminates there will be a hydrodynamical bouncing flow in the outward radial direction giving an outward impulse to the vessel wall. In the absence of friction a symmetric oscillation picture emerges. Clearly, a supply of repetitive pulses will be needed (at parametric resonance) to make the effect appreciable. The effect has to our knowledge not been discussed before. We give an approximate optical and hydrodynamical theory of it. The calculations indicate promising results for the wall pressure, although experimental work is desirable to show whether the idea can be useful in practice. Our calculation is made from a general physical perspective, not necessarily linked to medical applications.