Abdominal aortic aneurysms (AAAs) represent a focal dilation of the aorta exceeding 1.5 times its normal diameter. It is reported that 4–8% of men and 0.5–1% of women above 50 years of age bear an AAA. Rupture represents the most disastrous complication of aneurysmal disease that is accompanied by an overall mortality of 80%. Autopsy data have shown that nearly 13% of AAAs with a maximum diameter ≤ 5 cm were ruptured and 60% of the AAAs > 5 cm in diameter never ruptured. It is therefore obvious that the “maximum diameter criterion,” as a single parameter that fits all patients, is obsolete. Investigators have begun a search for more reliable rupture risk markers for AAA expansion, such as the level and change of peak wall stress or AAA geometry. Furthermore, it is becoming more and more evident that intraluminal thrombus, which is present in 75% of all AAAs, affects AAA features and promotes their expansion. Though these hemodynamic properties of AAAs are significant and seem to better describe rupture risk, they are in need of specialized equipment and software and demand time for processing making them difficult in use and unattractive to clinicians in everyday practice. In the search for the addition of other risk factors or user-friendly tools which may predict AAA expansion and rupture the use of the asymmetrical intraluminal thrombus deposition index seems appealing since it has been reported to identify AAAs which may have an increased or decreased growth rate.

Objective: to investigate the affect of reduced aortic compliance on cardiovascular hemodynamics. Materials and Method: fourteen Yucatan miniature swine were divided into two equal groups, a Sham Operated Group and a Banding Group. A Teflon prosthesis was wrapped around the aortic arc in order to limit proximal aortic compliance (Banding Group). Data were recorded operatively (after implantation of a pressure sensor and a flow probe in the ascending aorta), after banding (only in the Banding Group) and at 2 days postoperatively. Results: after banding, compliance decreased by 52 ± 13% (X̄ ± SEM) (p < 0.01) while systolic and pulse pressure increased by 37 ± 8% (p < 0.05) and 87 ± 31% (p < 0.01), respectively. Diastolic pressure, mean blood pressure, cardiac output and systemic vascular resistance did not change significantly. Aortic characteristic impedance increased nearly 2.5 times. Amplitudes of forward and reflected pressure waves (derived from the aortic pressure wave) increased by 96 ± 41% and 174 ± 46%, respectively (p < 0.05), while the time delay between the two decreased by 36 ± 7% (p < 0.05). Conclusions: about half of the total arterial compliance is located in the proximal thoracic aorta. Arterial reconstruction of the proximal aorta with a non-compliant graft results in a significant decrease in systemic arterial compliance, which in turn increases systolic and pulse pressure. The development of more compliant prosthesis, which matches the host artery compliance, is expected to reduce the hemodynamic changes induced after their implantation.

Aim: It was the aim of this study to investigate the long- term effects of reduced aortic compliance on cardiovascular hemodynamics and cardiac remodeling. Method: Sixteen swine, divided into 2 groups, a control and a banding group, were instrumented for pressure and flow measurement in the ascending aorta. Teflon prosthesis was wrapped around the aortic arch in order to limit wall compliance in the banding group. Hemodynamic parameters were recorded throughout a 60-day period. After sacrifice, the mean cell surface of the left ventricle was documented. Results: Banding decreased aortic compliance by 49 ± 9, 44 ± 16 and 42 ± 7% on the 2nd, 30th and 60th postoperative day, respectively (p < 0.05), while systolic pressure increased by 41 ± 11, 30 ± 11 and 35 ± 12% (p < 0.05), and pulse pressure by 86 ± 27, 76 ± 21 and 88 ± 23%, respectively (p < 0.01). Aortic characteristic impedance increased significantly in the banding group. Diastolic pressure, cardiac output and peripheral resistance remained unaltered. The mean left ventricular cell surface area increased significantly in the banding group. Conclusions: Acute reduction in aortic compliance results in a significant increase in characteristic and input impedance, a significant decrease in systemic arterial compliance and a subsequent increase in systolic and pulse pressures leading to left ventricular hypertrophy.