Converting and Standardizing Various Measures of Arterial Stiffness to Pulse Wave Velocity

Are aortic biomechanical properties early markers of dilatation in patients with Marfan syndrome? A systematic review and meta-analysis

Although tissue stiffness is known to play an important role in aortic dilatation, the current guidelines for offering preventative surgery in patients with Marfan syndrome rely solely on the aortic diameter. In this systematic review and meta-analysis, we analyze and compare literature on in vivo aortic stiffness measures in Marfan patients. Our aim is to assess the potential of these measurements as early indicators of aortic dilatation. Following the PRISMA guidelines, we collected literature on diameter and three in vivo stiffness measures: Pulse wave velocity (PWV), β -stiffness index (SI) and distensibility, at five different aortic locations in patients with Marfan syndrome. Results were reviewed and compared against each other. For meta-analysis, an augmented dataset was created by combining data from the literature. Regression with respect to age and statistical comparisons were performed. Thirty articles reporting data from 1925 patients with Marfan and 836 patients without Marfan were reviewed. PWV was found to be higher in Marfan, but only in dilated aortas. Distensibility was found to be lower even in non-dilated aortas, and its decrease was associated with higher chances of developing aortic dilatation. β -SI was higher in Marfan patients and was positively correlated with the rate of aortic dilatation, emphasizing its role as a valuable indicator. In our meta-analysis, all stiffness measures showed a significant variation with age. Distensibility and β -stiffness index were different in Marfan patients at all locations, and the difference was more pronounced after accounting for age-related variation. From the literature, β -SI and distensibility emerge as the best predictors of future aortic dilatation. Our meta-analysis quantifies age-related changes in aortic stiffness and highlights the importance of accounting for age in comparing these measurements. Missing diameter values in the literature limited our analysis. Further investigation of criteria combining stiffness and diameter is recommended to better assist clinical decisions for prophylactic surgery.

Variations of arterial compliance and vascular resistance due to plaque or infarct in a single vascular territory of the middle cerebral artery

Background

Arterial compliance (AC) and vascular resistance (VR) are crucial for the regulation capacity of the vascular system. However, alterations of these features and hemodynamics due to atherosclerosis in a single intracranial artery territory have not been extensively investigated. Thus this study aimed to examine the AC, VR, and hemodynamic variations due to plaque and infarction in the middle cerebral artery (MCA).

Methods

Patients with symptomatic MCA atherosclerosis were recruited. Both sides of the MCA were assessed and then classified according to the following scheme: group 0, without plaque; group 1, with plaque but without infarct; group 2, with plaque and infarct in the supplying territories. Data on AC, VR, blood flow, and pulsatility index (PI) were obtained based on 4D flow magnetic resonance imaging (MRI) and the Windkessel model.

Results

A total of 63 patients were recruited. After 17 MCAs were excluded (occlusion, n=6; poor image quality, n=11), datasets on 109 MCAs were finally collected and classified into group 0 (n=39), group 1 (n=40), and group 2 (n=30). From groups 0 to 2, there was a decrease in AC (0.0060±0.0031 vs. 0.0052±0.0029 vs. 0.0026±0.0020 mL/mmHg) and an increase in VR [28.65±16.11 vs. 42.59±27.53 vs. 63.21±40.37 mmHg/(mL/s)]. Compared to group 1, group 2 had significantly decreased AC (0.0052±0.0029 vs. 0.0026±0.0020 mL/mmHg; P=0.003) and increased VR [42.59±27.53 vs. 63.21±40.37 mmHg/(mL/s); P=0.021]. From group 0 to group 2, there was a decrease in blood flow (179.29±73.57 vs. 125.11±59.04 vs. 92.05±48.79 mL/min; P<0.001). The PI varied significantly among the 3 groups (0.86±0.20 vs. 1.12±0.50 vs. 0.79±0.16; P<0.001), with group 1 having the highest PI.

Conclusions

With the occurrence of plaque and infarct, AC and blood flow progressively decrease while VR increases. The PI was the highest in the group with plaque and without infarct. Assessments of vascular function and hemodynamics in a single artery territory can clarify comprehensive alterations in the cerebral vascular system (CVS).

Periorbital venous stasis may be involved with filler induced malar edema-A duplex ultrasound-imaging-based case series

INTRODUCTION

Filler injections in the periocular region are regarded as a challenging and advanced maneuver in a high-risk area. Adverse events as malar edema due to filler treatment may occur. To evaluate the possible reasons, the ultrasound images, and medical data of patients that were prospectively referred with malar edema were evaluated.

MATERIALS AND METHODS

A total of 17 patients (26 eyes) with malar edema after hyaluronic acid filler treatment were included. All cases were assessed with an 18 MHz linear ultrasound device. Exact location of the filler material was noted. Relations with clinical data were analyzed using chi-square tests.

RESULTS

Onset of malar edema after treatment showed a wide range from immediate (0 days) to 3 years. Most patients had an early onset N = 13 (76%), a minority showed late onset N = 4 (24%). In 23 eyes, the filler material was found to be located inside the SMAS. In 3 cases filler material was located on the periosteum of the orbital rim. After duplex-ultrasound guided filler removal, restored venous flow could be seen in the superficial and/or deep fatty layer often accompanied by flow piercing through the SMAS. Minutes after treatment, clinical improvement of malar edema was observed.

CONCLUSION

Malar edema after by filler treatments in the periocular region may be caused by veno-lymphatic compression by filler deposits.

Effects of body positions on arterial stiffness as assessed by pulse wave velocity

BACKGROUND

Assessing arterial stiffness through pulse wave velocity (PWV) usually requires participants to be in a supine position. If this position is not feasible, adjustments such as tilting the bed or bending the knees may be made. The Vicorder device also recommends tilting the upper body to prevent jugular vein interference in the recorded carotid pulse.

OBJECTIVE

To examine the impact of varying body positions on PWV.

METHODS

Seventy adults were studied in the fully supine (0°) to 40° upper body tilted-up positions with and without knee bend. Carotid-femoral PWV (cfPWV) was measured using two different testing devices (Omron VP-1000plus and Vicorder) and brachial-ankle PWV (baPWV) was measured using Omron.

RESULTS

cfPWV measured at 10° tilt-up was not different from 0° position while baPWV increased significantly from 10°. Elevations in cfPWV were 7% at 20° and 15% at 40° compared with 0° position. Knee bend did not affect cfPWV but decreased baPWV at each angle ( P  < 0.05). Jugular vein interference on the Vicorder was observed in 78% of participants in supine position, decreasing as body angle increased (7% at 30°). However, cfPWV values measured by Vicorder were consistent with those obtained by Omron even with jugular vein interference.

CONCLUSION

Arterial stiffness assessed by PWV increased gradually and significantly in semi-Fowler's position ≥20°. Knee bend decreased baPWV but did not seem to affect cfPWV. PWV should be measured in supine position if possible. If the supine posture is not tolerated, knee bend followed by a slight incline position may be recommended.