Characterization of tibial velocities by duplex ultrasound in severe peripheral arterial disease and controls

Pathology of Critical Limb Ischemia; Comparison of Plaque Characteristics Between Anterior and Posterior Tibial Arteries

AIMS

Though the number of patients with peripheral arterial disease (PAD) and critical limb ischemia (CLI) is increasing, few histopathological studies of PAD, particularly that involving below-the-knee arteries, has been reported. We analyzed the pathology of anterior tibial artery (ATA) and posterior tibial artery (PTA) specimens obtained from patients who underwent lower extremity amputation due to CLIMethods: Dissected ATAs and PTAs were subjected to ex-vivo soft X-ray radiography, followed by pathological examination using 860 histological sections. This protocol was approved by the Ethics Review Board of Nihon University Itabashi Hospital (RK-190910-01) and Kyorin University Hospital (R02-179).

RESULTS

The calcified area distribution was significantly larger in PTAs than in ATAs on soft X-ray radiographic images (ATAs, 48.3% ±19.2 versus PTAs, 61.6% ±23.9; p＜0.001). Eccentric plaque with necrotic core and macrophage infiltration were more prominent in ATAs than in PTAs (eccentric plaque: ATAs, 63.7% versus PTAs, 49.1%; p＜0.0001, macrophage: ATAs, 0.29% [0.095 - 1.1%] versus PTAs, 0.12% [0.029 - 0.36%]; p＜0.001), histopathologically. Thromboembolic lesions were more frequently identified in PTAs than in ATAs (ATAs, 11.1% versus PTAs 15.8%; p＜0.05). Moreover, post-balloon injury pathology differed between ATAs and PTAs.

CONCLUSIONS

Histological features differed strikingly between ATAs and PTAs obtained from CLI patients. Clarifying the pathological features of CLI would contribute to establishing therapeutic strategies for PAD, particularly disease involving below-the knee-arteries.

Accuracy of the pedal acceleration time to diagnose limb ischemia in patients with and without diabetes using the WIfI classification

INTRODUCTION

Evaluation of limb hemodynamics using the ankle-brachial index (ABI) may be difficult due to skin lesions, extensive necrosis, and obesity, such as commonly present in patients with diabetes with chronic limb-threatening ischemia (CLTI). We hypothesized that the pedal acceleration time (PAT) correlates with ABI and Wound, Ischemia, and foot Infection (WIfI) scores in patients with diabetes to serve as a new modality to accurately stage CLTI.

METHODS

A single-center, cross-sectional study included patients with and without diabetes > 18 years with CLTI. Limbs were categorized in three grades of ischemia based on the ABI (ABI < 0.8, < 0.6, and < 0.4) and in two classes based on WIfI stages of amputation risk. Receiver operator characteristic (ROC) curves were used to determine PAT sensitivity, specificity, and accuracy to predict lower-limb ischemia.

RESULTS

A total of 141 patients (67 nondiabetic and 74 diabetic) and 198 lower limbs (94 nondiabetic and 104 diabetic) met the inclusion criteria. In patients without diabetes, the accuracy of PAT for detecting an ABI < 0.8 was 85%; for detecting an ABI < 0.6 was 85%; and for detecting an ABI < 0.4 was 87%. In patients with diabetes, the accuracy of PAT in detecting an ABI < 0.8 was 91%; for detecting an ABI < 0.6 was 79%; and for detecting an ABI < 0.4 was 88%. In patients without diabetes, the accuracy for detecting WIfI stages of moderate and high amputation risk was 77% and for patients with diabetes was also 77%.

CONCLUSIONS

PAT shows high correlation with the ABI as well as with the WIfI stages of amputation risk and the grades of ischemia, with high accuracy.

Pulsatility index-adjusted doppler flow measurement of pedal arteries in peripheral artery disease patients

BACKGROUND

To examine the feasibility of using pulsatility index-adjusted (PI) flow equations to accurately characterize blood volume flow changes using Doppler technique in patients with peripheral artery disease (PAD) before and after percutaneous transluminal angioplasty (PTA).

METHODS

PTA was performed on 17 PAD patients (23 target vessels treated, 16 anterior tibial arteries, and 7 posterior tibial arteries). Arterial diameter, peak systolic velocity, PI, time-averaged mean velocity, and measured volume flow (MVF) of dorsalis pedis artery (DPA) and common plantar artery (CPA) were measured with duplex Doppler ultrasound before and after PTA. PI-adjusted volume flows (PIVF) were calculated as part of the MVF/PIVF relative percentage metric.

RESULTS

Significant changes (p < 0.001) of the MVF (mean: 33.0 mL/min, range: -20.9-102.2 mL/min) and MVF/PIVF relative percentages (mean: 51.8, range: 5.1-127.2%) in the DPA existed between before and after PTA, whereas no significant changes could be found in the CPA (mean:10.9 mL/min, p = 0.148 and mean: 21.3%, p = 0.146, respectively). Of the 7 treated posterior tibial arteries, the increments of the MVF/PIVF (mean: 60.4%, p = 0.033) was significant but not in the MVF (mean: 26.5 mL/min, p = 0.125). The ankle-brachial index also showed non-significant changes (p = 0.081). All PI-adjusted results matched clinical observations after blood flow restoration.

CONCLUSION

No conclusions can be drawn from the comparison of actual measured volume flow between before and after PTA. However, using the MVF/PIVF relative percentage allows for a more objective framework upon which to base clinical observations and provides clarity in situations where direct measurement provides a counter-intuitive or contradictory picture.

Abnormal Lower Extremity Hemodynamics at Doppler US in Children with Sickle Cell Anemia

Background Children with sickle cell anemia (SCA) are predisposed to developing leg ulcers in early adolescence; however, the underlying physiologic mechanisms are not well understood, which hinders the development of prophylactic antiulcer interventions. Purpose To determine if occlusive arterial disease or abnormal hemodynamics exist in the lower limb peripheral arteries of children with SCA. Materials and Methods This was a prospective cross-sectional study conducted between July 2020 and May 2021. Two groups of participants were enrolled: children with SCA and healthy controls. Each child had their anthropometric measurements taken, followed by B-mode, color Doppler, and spectral Doppler US evaluation of the distal anterior and posterior tibial arteries. Ankle-brachial index evaluation was also performed. Hemodynamic values were compared between children with SCA and healthy controls, with statistical significance set at the P < .05 level. Results Forty-five children with SCA (mean age, 9.5 years ± 3.7 [SD]; 26 boys) and 45 healthy controls (mean age, 9.3 years ± 3.8; 25 boys) were evaluated. Children with SCA had higher peak systolic velocities, end-diastolic velocities, and blood volume flow in their distal anterior and posterior tibial arteries compared with the healthy participants (P < .001 across all 12 measurements). Children with SCA also had lower resistive index and pulsatility index values compared with healthy controls in at least one of the anterior and posterior tibial arteries bilaterally. Monophasic spectral patterns were exclusively observed in participants with SCA. The ankle-brachial index values for the participants with SCA (mean, 1.09 ± 0.08) and healthy participants (mean, 1.06 ± 0.02) were within normal range. Conclusion Abnormal peripheral hemodynamic characteristics were found in the lower limbs of children with sickle cell anemia. No evidence of occlusive peripheral artery disease was present. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Paltiel in this issue.

Volume Flow and Peak Systolic Velocity of the Arteriovenous Circuit in Patients after Percutaneous Deep Venous Arterialization

Percutaneous deep venous arterialization (pDVA) is a developing technique for limb salvage in patients with chronic limb-threatening ischemia by creating an arteriovenous (AV) circuit. After pDVA, patency of the AV circuit is evaluated using duplex ultrasound (DUS) imaging. Peak systolic velocity (PSV) and volume flow (VF) values for maintaining a patent AV circuit are undefined; therefore, guidance about when a reintervention should be performed is lacking. The objective of this study was to interpret post-pDVA PSV and VF values in relation to AV circuit preservation. This was performed by analyzing DUS results of 22 post-pDVA patients. A total of 670 PSV and 623 VF measurements were collected. A PSV value of ≤55 cm/s and a VF value of ≤195 mL/min were found predictive for failure. The reliability of PSV and VF measurements in patent AV-circuits was good (intraclass correlation coefficient; PSV, 0.85; VF, 0.88). In conclusion, this study is the first to analyze DUS measurements in post-pDVA patients and showed that DUS can be used to anticipate for failure. The thresholds found can be used to help interpret DUS measurements in post-pDVA patients. More research in a larger patient population is needed to prospectively validate these thresholds.

Tibial artery velocities in the diagnosis and follow-up of peripheral arterial disease

Physiologic assessment of lower limb peripheral artery occlusive disease is based on indirect physiologic measurement of ankle-brachial systolic pressure index (ABI) and recording ultrasound tibial artery waveforms. Duplex ultrasound testing affords direct tibial artery imaging and assessment of pulsed-Doppler tibial artery waveforms, which is more accurate then measurement of ABI for peripheral artery occlusive disease severity assessment. Tibial artery peak systolic velocity (PSV) is of particular value in the evaluation of patients with incompressible tibial arteries producing a falsely elevated ABI. Calculation of the ankle-profunda index (average tibial artery PSV/proximal profunda femoris artery PSV) also correlates with ABI reduction and can be used as an additional measure of peripheral artery occlusive disease. Tibial artery PSVs can be used to supplement ABI as an objective outcome measure after peripheral arterial interventions, and this aspect of duplex scanning warrants further clinical research.

Platelets reflect the fate of type II endoleak after endovascular aneurysm repair

OBJECTIVE

The management of type II endoleak (T2E) remains controversial because of the heterogeneous outcome. For blood-based screening to detect malignant T2E, we focused on platelets after endovascular aneurysm repair (EVAR) and compared them with the prognosis of T2Es.

METHODS

From 2007 to 2015, there were 249 patients treated with EVAR for abdominal aortic aneurysm who were evaluated retrospectively. The mean follow-up period was 3.5 ± 0.2 years. T2Es that had aneurysm sac enlargement or converted to type I or type III endoleak were defined as malignant; the other T2Es were considered benign. Cases without any complications, including T2E, were defined as completed. We compared the platelet count on postoperative days (PODs) 1 to 7 with preoperative baseline values among the three groups. Sequentially, we calculated the cutoff of the platelet ratio on POD 7 to the baseline value in relation to malignant T2E using receiver operating characteristic analysis, and the cutoff ratio was 113% (sensitivity, 79%; specificity, 58%). We then reclassified T2E patients into T2E-high platelet (T2E-HP; ≥113%) or T2E-low platelet (T2E-LP; <113%) groups. The influence of platelets on T2E was evaluated with reintervention rate and cumulative aneurysm sac enlargement rate using the Kaplan-Meier method.

RESULTS

T2Es were found in 70 patients (28%), and 179 patients were assigned to the completed group. Malignant and benign T2Es were found in 33 and 37 patients, respectively. No difference was found in the preoperative baseline values. On POD 7, the platelet count in the malignant T2E group was significantly lower than that in the completed and benign T2E groups (168 × 10³/μL vs 207 × 10³/μL and 201 × 10³/μL; P = .0124). Then, 27 and 43 patients were assigned to the T2E-HP and T2E-LP groups, respectively. The reintervention-free survival rate in the T2E-LP group was lower than that in the completed group (at 3 years, 66.4% ± 8.0% vs 71.9% ± 4.0%; P = .0031). Among T2E patients, the cumulative aneurysm sac enlargement rates in the T2E-LP group were significantly higher than those in the T2E-HP group (at 3 years, 34.6% ± 8.2% vs 20.6% ± 8.2%; P = .0105). Univariate Cox proportional hazards analysis for the cumulative aneurysm sac enlargement rates among T2E patients showed that sex, dual antiplatelet therapy, and lower platelet ratio (<113%) were significant predictors; multivariate analysis showed that T2E-LP was the only significant predictor (hazard ratio, 2.60; P = .0355).

CONCLUSIONS

The platelet count of patients with malignant T2Es on POD 7 was definitively lower than that of patients with completed EVAR or with benign T2Es. The lower platelet count on POD 7 could be a risk factor for aneurysm sac enlargement among patients with T2Es.