Designing an Experimental Protocol for Separating Active Diameter Response from Passive Response in Small Blood Vessels

Abstract: The knowledge of blood vessel biomechanics is used for understanding and developing treatments for cardiovascular disease. The objective of this project was to develop an experimental protocol, for education and research, that separates active diameter response from the passive, as a function of the intraluminal pressure in a pressure myograph. The design process was performed in three steps. First the protocol was designed for an artificial vessel and then expanded to include passive properties of blood vessels, finally further developments needed to analyze active blood vessels were suggested. The system was built as a pressure myograph containing a vessel chamber where the vessel was mounted on two cannulas, two pressure sensors for calculating the intraluminal pressure, and one microscope equipped with a camera for diameter observations. Reference data for the artificial vessel material was acquired from a uniaxial tensile test. The results was in the form of stress-stretch relations. Both the results from the artificial vessel and the passive blood vessel was in a acceptable reference range. The results indicate that the experimental protocol can be used for testing passive properties of both artificial vessels and small blood vessels. No results were obtained for active blood vessels, thus the experimental protocol can not be used for separating the active response to diameter change of blood vessels. However, further developments of the experimental protocol are discussed.