Effect of surrounding tissue-mimicking gelatin in the mechanical properties of arteries

Arterial elasticity has become an important predictor of cardiovascular diseases and mortality. Pulse wave velocity (PWV) is the most widely used method despite its disadvantages, which have prevented this technique from becoming a clinical tool. In our laboratory we have developed an ultrasound radiation force based technique to generate mechanical waves in the arterial wall. The speed and modes of propagation of these induced waves are used to estimate the mechanical properties of the vessel wall. In this work, we present a study done on excised carotid arteries from 8 healthy, young pigs. We compared the effect of surrounding tissuemimicking gelatin on the elasticity properties by testing the arteries embedded and not embedded in the gelatin as an evaluation of the effects of surround tissue. We also evaluated the effect of stretch on the Young's modulus but changing the prestretch in the artery at 3 different levels. The results showed that there was little difference in the Young's modulus of the arteries when loaded with or without gelatin. The Young's modulus increased from 80 kPa at 10 mmHg to 160 kPa at 100 mmHg. The levels of stretch significantly changed the behavior of the Young's modulus with pressure, for 7 cm stretch the modulus increased from 81 kPa at 10 mmHg to 192 kPa at 100 mmHg; for 8 cm, the modulus increased from 120 to 367 kPa and for the 9 cm stretch in increased from 623 to 734 kPa. This technique has the potential to study the mechanical properties of the arterial wall in a noninvasive, quantitative and reproducible manner. We showed that the loading of soft tissue around the arteries does not change significantly the mechanical properties, while the level of stretch plays a significant role.