A group of physicists has solved a surgical mystery that has puzzled doctors for over 70 years. When a patient suffers high blood pressure, small blood vessels tend to alternately constrict and dilate along their length, forming a "sausage-string" pattern that is damaging to the patient. Previously physicians had thought that the blood vessels had suffered a "blow-out", but closer examination by Finn Gustafsson and colleagues in Denmark and Spain reveals that the blood pressure is too small to cause such an effect. Instead they suggest that the elasticity characteristics of the vein cause the problem. The work has been submitted to Physical Review Letters.