Determinants of central aortic pressure and pulse pressure amplification changes in patients with aortic aneurysm: the role of aortic diameter and aortic aneurysm location level

Abstract

Background The presence of aortic aneurysm can alters pulse wave propagation and reflection, causing changes in central aortic pressure and pulse pressure amplification (PPA) between the aorta and the brachial artery that might be associated with unfavorable hemodynamic effects for the central arteries and the heart. However, the impact of the location of the aneurysm and increase of the aortic diameter on central blood pressure (CBP) is not fully understood. Objective To investigate central aortic pressure and PPA regarding to association with arterial stiffness and aortic diameter in patients with ascending aortic aneurysm (AA), descending thoracic and abdominal aortic aneurysm (TAA and AAA). Methods 122 patients (96 males, 65±11 years) with aortic aneurysm were enrolled before aortic repair. The parameters of the aorta were evaluated by MSCT angiography: 44 patients (30 males, 55±13 years) had AA (the maximum diameter: 59.9±14.2 mm), 13 patients (11 males, 62±11 years) had TAA (the maximum diameter: 62.8±8.0 mm) and 65 patients (54 males, 69±8 years) had AAA (the maximum diameter: 52.3±17.2 mm). Brachial blood pressure (BBP) was measured by OMRON. CBP, augmentation index (AIx), carotid-femoral pulse wave velocity (PWV) were assessed by SphygmoCor. PPA was calculated as a difference between the values of central and brachial pulse pressure (CPP and BPP). Results Patients of the three groups did not differ in BPP (AA: 59.2±17.6; TAA 56.8±12.8; AAA: 59.3±11.4 mm Hg; P=0.5). Intergroup comparison revealed a difference in CPP between the three patients groups: CPP was higher in patients with AA and AAA, lower in patients with TAA (AA: 50.3±16.2; TAA 43.8±10.8; AAA: 50.0±11.2 mm Hg; P=0.05). PPA was lower in patients with AA and AAA than in patients with TAA (9.6±6.7 and 9.3±4.2 vs. 13.0±6.5 mm Hg; P=0.05 and P=0.04, respectively). IAx was higher in patients with AA and AAA than in patients with TAA (25.2±8.1 and 27.6±8.2 vs. 17.2±8.2 mm Hg; P=0.008 and P=0.001, respectively). A decrease of PPA across all patients correlated with an increase of IAx (r = - 0.268; P=0.003). CPP decreased with an increase of the aortic diameter for each level of the aneurysm (AA: r = - 0.460, P=0.016; TAA: r = - 0.833, P=0.003; AAA: r = - 0.275, P=0.05). PWV decreased with the expansion of the maximum aortic diameter at the level of the AA, TAA and AAA: (r = - 0.389, P=0.03; r = - 0.827, P=0.02 and r = - 0.350, P=0.01, respectively). Conclusion In patients with aortic aneurysm measurements of lower central pulse pressure and reduced PWV indicate an association with increased diameter of the aneurysm. An increase in augmentation index, early return of reflected waves, thus smaller PP amplification and higher CPP were identified in patients with ascending and abdominal aortic aneurysm compared by patients with descending thoracic aortic aneurysm. Funding Acknowledgement Type of funding source: None

Signatures of obstructions and expansions in the arterial frequency response

“…14). This result correlates with in-vivo measurements in patients with aortic aneurysms, where the radius increase has been associated with a lower central pulse pressure [3]. In addition, other numerical studies have found a decrease in the amplitude of the blood pressure and flow due to aneurysms [44].…”

“…Abnormal geometry alterations caused by pathological conditions such as local expansions (aneurysms) and reductions (stenoses) of the radius, modify the pulse waveforms. For instance, in patients with aortic aneurysms, the increase in the radius has been associated with a lower central pulse pressure and a smaller PWV [3]. Waveform analysis in healthy and pathological conditions can be performed in the time or frequency domains [4][5][6].…”