Abstract
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.