Relationship between aortic flow propagation velocity and ankle-brachial index in peripheral artery disease

Objective: Peripheral artery disease (PAD) is primarily caused by the progressive narrowing of the arteries in the lower extremities and serves as an indicator of systemic atherosclerosis. The etiopathogenesis of PAD is fundamentally linked to atherosclerosis and its complications. Arterial stiffness plays a direct role in the progression of atherosclerosis. Cardiovascular risk factors such as hypertension, diabetes and hyperlipidemia can alter the structure, function and stiffness of the arteries. Atherosclerosis is a widespread disease that also affects large vessels, including the thoracic aorta, leading to thickening and stiffening of the arterial wall. Consequently, this results in increased arterial resistance and a subsequent decrease in flow propagation velocity within the arterial lumen. Aortic flow propagation velocity (AVP) has been evaluated as a novel parameter reflecting aortic stiffness and, consequently, atherosclerosis. The ankle-brachial index (ABI) is a well-established, simple and noninvasive procedure frequently used in clinical practice for the diagnosis of PAD. The aim of this study was to demonstrate the contribution of ABI and AVP to the noninvasive diagnosis of PAH in patients with angiographically diagnosed PAH and control group patients without PAH. Materials and Methods: The study included 101 patients diagnosed with PAD via conventional peripheral angiography (PAG) or computed tomographic angiography (CTA) (defined as having ≥50% stenosis in the peripheral arterial system) and 101 control patients without suspected PAD based on medical history and physical examination findings. All participants were recruited from the Cardiology Outpatient Clinic of Akdeniz University Hospital between November 2022 and November 2024. Systolic blood pressures of the brachial, anterior tibial, and posterior tibial arteries were measured using a mercury sphygmomanometer with an inflatable cuff. The ankle-brachial index (ABI) was calculated by dividing the highest ankle arterial pressure by the highest brachial arterial pressure. Echocardiographic examinations were performed in the Echocardiography Laboratory of the Cardiology Department at Akdeniz University, using a Philips Affiniti 70C echocardiography device equipped with a 3.5 MHz phased-array harmonic probe. Following routine echocardiographic assessments, from the suprasternal window in supine position the diameter of the descending aorta was measured just distal to the subclavian artery and color Mmode Doppler recordings were obtained by adding cursor parallel to the main flow of direction. The color Doppler Nyquist limit is adapted to 30–50 cm/s and by switching to Mmode, an M-mode spatio-temporal velocity map in the form of a flame is displayed with a recorder sweep rate of 200 mm/s. If the slope of the flame was unclear, baseline shifting was used to change the aliasing velocity until a clear delineation of the isovelocity slope was seen. AVP was then calculated by dividing the distance between the points corresponding to the beginning and end of the propagation slope by the duration between the corresponding time points. AVP thus corresponds to the velocity at which the flow is propagated down the artery. The final AVP value was recorded as the mean of at least three measurements. Findings: Among the patients included in the study, 28.2% were female, and 71.8% were male. The mean age was similar between the two groups. In the PAD group, the prevalence of male sex, diabetes mellitus (DM), hyperlipidemia (HPL) and coronary artery disease (CAD) was significantly higher (p<0.001 for DM and CAD; p=0.019 for sex). Additionally, a statistically significant difference was observed between the PAD and control groups in terms of smoking prevalence (p=0.02). However, there was no statistically significant difference in LDL levels between the two groups (p=0.098). Echocardiographic evaluation revealed that left ventricular wall thickness was significantly greater in the PAD group compared to the control group (p<0.0001 for IVSDd and p=0.001 for PWDd). The E/A ratio was also significantly lower in the PAD group (mean: 0.82±0.26) compared to the control group (p=0.001). The mean AVP value in the PAD group was 34.65±10.67 cm/s, with the lowest AVP recorded at 14.8 cm/s. In contrast, the mean AVP in the control group was 69.5±14.27 cm/s. The AVP values in the PAD group were significantly lower than those in the control group (p<0.0001). In the control group, the mean ABI was 1.19±0.07, with a minimum value of 1.0 and a maximum of 1.34. In the PAD group, the mean ABI was 0.71±0.18, with a minimum value of 0.27 and a maximum of 1.2. A statistically significant difference was observed in ABI values between the groups (p<0.0001). A statistically significant moderate positive correlation was found between AVP and ABI (r=0.697, p<0.0001). When the relationships between AVP, E/A ratio and HbA1c were examined (Table 4.8), a statistically significant weak positive correlation was found between AVP and E/A ratio (r=0.314, p<0.0001). Conversely, a statistically significant weak negative correlation was observed between AVP and HbA1c (r=-0.402, p<0.0001). Regarding the relationship between sex and AVP, AVP measurements in females were found to be significantly higher than those in males (p=0.022). Conclusion: In our study, ABI and aortic flow AVP were measured in a group of patients diagnosed with PAD and in a control group without PAD. It was found that AVP was significantly lower in patients with PAD compared to the control group (p<0.0001). Furthermore, AVP was shown to be correlated with ABI, a well-established diagnostic test for PAD (r=0.697, p<0.0001). This suggests that AVP could serve as a complementary diagnostic tool to ABI and may be particularly useful as an alternative test in cases where ABI measurement is limited or inconclusive. Key Words: Atherosclerosis, Peripheral Artery Disease, Arterial Stiffness, Aortic Flow Propagation Velocity