The Aortic Wrap Procedure – A Surgical Method of Treating Age-Related Aortic Dilatation and Stiffness

Introduction: There is progressive stiffening and dilatation of the aorta and large elastic arteries with aging as a result of the repetitive cyclic stress they are exposed to throughout life. Aortic stiffening has a number of detrimental effects including an increase in aortic pulse wave velocity and early wave reflection, isolated systolic hypertension, ventricular-vascular mismatch, impaired coronary blood flow reserve, and is the fundamental cause of heart failure in the elderly. The aim of this thesis is to provide proof of concept for the aortic wrap procedure; a surgical treatment of stiffening and dilatation of the ascending aorta with aging. The surgical procedure involves wrapping an elastic material around the ascending aorta of elderly patients, to reduce the stiffness and diameter of the ascending aorta towards that seen in youth.

Methods: Proof of concept is investigated in the following studies.
1. The effect of the elastic wrap on the in-vivo stiffness of the normal aorta.
2. The effect of the elastic wrap on the in-vivo stiffness of the dilated and stiffened aorta.
3. The effect of the elastic wrap on the in-vitro stiffness of the aged human ascending aorta and on aortic pressure.
4. The effect of wrapping the aged human ascending aorta on pulse pressure (mathematical model).
5. The effect of chronic implantation on the structure of the normal aorta.
6. The mechanical properties of the ovine thoracic aorta and the elastic wrap material.

Results:
1. Elastic wrap application increased the in-vivo stiffness of the normal aorta.
2. Elastic wrap application decreased the stiffness of the stiffened and dilated aorta.
3. Elastic wrap application decreased the in-vitro stiffness of the elderly human ascending aorta and pulse pressure.
4. A reduction in ascending aortic stiffness was sufficient to reduce ascending aortic pulse pressure.

Conclusion: Application of the elastic wrap to the aged human ascending aorta is expected to reduce aortic stiffness, as well as systolic and pulse pressure, and to increase diastolic pressure with a reduction in cardiac load. The aortic wrap procedure may be an effective surgical procedure for the treatment of heart failure and isolated systolic hypertension.