A Novel Aortic Coarctation Model for Studying Hypertension in the Pig

Abstract

We have developed a reproducible renovascular model of hypertension via a controllable, suprarenal aortic coarctation in the pig. This model has many potential applications, including investigation of the effects of acute hypertension in the conscious animal; identification of cardiac and vascular adaptations to chronic hypertension and their reversal; determining the effect of pharmacologic agents or other interventions on hypertension; and furthering our understanding of the implications of chronic hypertension on neurologic function. A totally implantable system was devised by attaching a reinforced silicone vascular occluder to a vascular access port. The occluder was placed around the suprarenal aorta proximal to the diaphragm. Ten pigs were made hypertensive by sequentially inflating the occluder. In six pigs, telemetric monitoring of blood pressure was used to determine when the pigs had reached target pressures (mean arterial blood pressure >150 mm Hg). Four pigs did not have telemetry units placed and blood pressure and heart rate were monitored for 4 weeks by periodically restraining the pigs in a sling. Two pigs reversed their occlusion due to presumed technical errors; the remaining pigs were studied for 4 (n = 5) or 8 (n = 3) weeks and then euthanized. Advantages of this model of aortic coarctation are that the occlusions are performed in awake animals and excessive occlusion of the aorta resulting in neurologic dysfunction or other distress to the animal can be easily corrected by simply withdrawing a small amount of the fluid used for inflation of the occluder. Additionally, removal of the constriction does not require a second surgical procedure.

Automated measurement and statistical modelling of elastic laminae in arteries

“…Nevertheless, despite our fundamentally different methods of analysis, our findings are consistent with those of [14, 22, 30], that is, LT is not uniformly distributed along the radial direction in general. As such, gross averages of point-wise measurements may fail to detect subtle changes of LT and ILD with time or location within the wall.…”

“…Cylindrical segments of excised porcine thoracic aorta from another study [22] were cut to release residual stresses and processed using standard histological methods (e.g., embedded, sectioned, and stained). Sections were stained with Verhoeff Van Gieson (VVG) to focus on intramural elastin (the main component of elastic laminae).…”

Biomechanics of the Porcine Basilar Artery in Hypertension

“…6 Briefly, a balloon-expandable occluder is pre-filled with a 50% dextrose solution, placed over a Gor-Tex soft tissue patch, and secured with suture around the aorta proximal to the diaphragm. The occluder is connected via stiff tubing to a vascular access port that is placed subcutaneously in the neck, which allows the occluder to be inflated or deflated in the conscious animal.…”

Modeling and Measurement of Elastic Laminae in Arteries

“…Recently developed porcine aortic coarctation model was used to study hypertension-induced G&R [2]. The porcine aorta represents a better model for studying potential stress-induced G&R than rodent arteries since the many elastic laminae enable us to study possible spatial changes, or gradient-mediated expressions, across the vessel wall.…”