Use of Fraction Flow Reserve to Predict Changes over Time in Management of Superficial Femoral Artery

Effectiveness of intra-arterial manometry in guiding femoral popliteal stent implantation: a prospective randomized controlled trial

BACKGROUND

Femoropopliteal artery occlusion is a prevalent peripheral arterial disease, and endovascular therapy has become the preferred treatment. Accurate assessment of balloon dilation efficacy is crucial for determining the necessity for subsequent stent implantation. This study aims to investigate the use of interlesion arterial pressure gradients as a novel approach to assess balloon dilation efficacy and guide stent implantation decisions.

METHODS

A prospective, randomized, controlled trial was conducted on 100 patients with femoropopliteal artery occlusion. Patients were randomized into a control group (n=50) and an experimental group (n=50). Stent implantation was performed in the control group according to standard indications, while the experimental group underwent stent implantation only if the mean arterial pressure gradient exceeded 10 mmHg or fractional flow reserve (FFR) fell below 0.85. Post-intervention, pressure measurements and angiography were used to evaluate residual stenosis, dissection, and pressure gradients.

RESULTS

Lesions were categorized into stent-indicated and non-indicated groups. In the non-stent-indicated lesions, the experimental group demonstrated significantly higher patency rates for lesions with pFFR < 0.85 or ΔP > 10 mmHg compared to the control group (92.9% vs. 50.0%, P=0.039). There was no significant difference in patency rates between the experimental and control groups for stent-indicated lesions.

CONCLUSION

Combining pressure measurement with angiography provides a more precise evaluation of balloon dilation efficacy and stent implantation indicators in femoropopliteal artery occlusive disease. Further research is needed to establish optimal pressure threshold values and refine treatment guidelines.

Utility and optimal dose of nicorandil for physiological assessment of the femoropopliteal artery

BACKGROUND

Nicorandil is widely used as a vasodilator for the physiological assessment of coronary arteries because of its usefulness and safety; however, there are no data on its use in peripheral arteries.

AIMS

To identify the utility of nicorandil and its appropriate dose for the physiological assessment on the femoropopliteal artery.

METHODS

We retrospectively enrolled patients from three institutes in which physiological assessment was carried out with various doses of nicorandil before treatment. Twenty-four femoropopliteal artery stenotic lesions from 22 patients were included. The nicorandil doses used were 2, 4, and 6 mg. Twenty-two lesions were also assessed using 30 mg of papaverine. The pressure gradient (PG) and peripheral fractional flow reserve (pFFR) were calculated based on the mean and systolic pressure levels. We examined the correlation of each parameter with the peak systolic velocity ratio (PSVR) based on the duplex ultrasound images using Spearman's rank correlation coefficient. Systemic blood pressure was assessed for safety.

RESULTS

The correlations were higher for mean pressure-based parameters than for systolic pressure-based parameters. As the nicorandil dose increased, the correlations among PG, pFFR, and PSVR also increased (mean pressure-based PG: 2 mg, r = 0.360; 4 mg, r = 0.498; 6 mg, r = 0.694, mean pressure-based pFFR: 2 mg, r = -0.479; 4 mg, r = -0.469; 6 mg, r = -0.641). The blood pressure after the administration of 6 mg of nicorandil was low, and the median systemic mean pressure was 65 mmHg.

CONCLUSION

A 4 mg dose of nicorandil is effective and safe for the mean pressure-based physiological assessment of lesions in the femoropopliteal artery.

Intra-arterial Fractional Flow Reserve Measurements Provide an Objective Assessment of the Functional Significance of Peripheral Arterial Stenoses

OBJECTIVE

Peripheral arterial stenoses (PAS) are commonly investigated with duplex ultrasound (DUS) and angiography, but these are not functional tests. Fractional flow reserve (FFR), a pressure based index, functionally assesses the ischaemic potential of coronary stenoses, but its utility in PAS is unknown. FFR in the peripheral vasculature in patients with limb ischaemia was investigated.

METHODS

Patients scheduled for angioplasty and or stenting of isolated iliac and superficial femoral artery stenoses were recruited. Resting trans-lesional pressure gradient (Pd/Pa) and FFR were measured after adenosine provoked hyperaemia using an intra-arterial 0.014 inch flow and pressure sensing wire (ComboWire XT, Philips). Prior to revascularisation, exercise ABPI (eABPI) and DUS derived peak systolic velocity ratio (PSVR) of the index lesion were determined. Calf muscle oxygenation was measured using blood oxygenation level dependent cardiovascular magnetic resonance prior to and after revascularisation.

RESULTS

Forty-one patients (32, 78%, male, mean age 65 ± 11 years) with 61 stenoses (iliac 32; femoral 29) were studied. For lesions < 80% stenosis, resting Pd/Pa was not influenced by the degree of stenosis (p = .074); however, FFR was discriminatory, decreasing as the severity of stenosis increased (p = .019). An FFR of < 0.60 was associated with critical limb threatening ischaemia (area under the curve [AUC] 0.87; 95% CI 0.75 - 0.95), in this study performing better than angiographic % stenosis (0.79; 0.63 - 0.89), eABPI (0.72; 0.57 - 0.83), and PSVR (0.65; 0.51 - 0.78). FFR correlated strongly with calf oxygenation (rho, 0.76; p < .001). A greater increase in FFR signalled resolution of symptoms and signs (ΔFFR 0.25 ± 0.15 vs. 0.13 ± 0.09; p = .009) and a post-angioplasty and stenting FFR of > 0.74 predicted successful revascularisation (combined sensitivity and specificity of 95%; AUC 0.98; 0.91 - 1.00).

CONCLUSION

This pilot study demonstrates that FFR can objectively measure the functional significance of PAS that compares favourably with visual and DUS based assessments. Its role as a quality control adjunct that confirms optimal vessel patency after angioplasty and or stenting also merits further investigation.

How much flow is enough: the use of fractional flow reserve in chronic limb-threatening ischemia in a series of patients with isolated occlusive tibial disease

The role of the fractional flow reserve to guide lower extremity peripheral vascular intervention, specifically in chronic limb-threatening ischemia, has remained unclear. This series presents a novel use of the fractional flow reserve in four patients to guide lower extremity endovascular interventions in patients with chronic limb-threatening ischemia.

Efficacy of pressure gradient measurement using peripheral fractional flow reserve in common femoral artery: a case report

Background

The severity of peripheral artery disease (PAD) is usually diagnosed by physiological assessments, such as the ankle brachial index (ABI) or peak systolic velocity (PSV) on ultrasonography. We examined peripheral fractional flow reserve (pFFR: distal mean pressure divided by proximal mean pressure) measured by a pressure wire and pressure gradient to diagnose PAD patients who do not have lowered ABI or high PSV on ultrasonography.

Case summary

An 84-year-old woman with intermittent claudication in her left leg had severe calcification in the left common femoral artery (CFA) on angiography. The exercise-stress ABI of pre-endovascular therapy (EVT) was 1.05/0.98. In addition, the PSV of the left CFA on ultrasonography was 230 cm/s. However, the pFFR using papaverine and alprostadil in the left CFA was 0.86, which was a significant score. In addition, the systolic pressure gradient between the distal and proximal regions was >20 mmHg. We performed EVT for the lesion, and the pFFR improved to 0.96. The systolic pressure gradient was only 1 mmHg at the lesion.

Discussion

Symptomatic PAD patients whose ABI or PSV on ultrasonography is insufficient for EVT could be diagnosed with ischaemia using a pressure gradient and pFFR.

Ankle-Brachial Index for Risk Stratification in Patients With Symptomatic Peripheral Artery Disease With and Without Prior Lower Extremity Revascularization: Observations From the EUCLID Trial

[Figure: see text].

Early modulation of macrophage ROS-PPARγ-NF-κB signalling by sonodynamic therapy attenuates neointimal hyperplasia in rabbits

Disruption of re-endothelialization and haemodynamic balance remains a critical side effect of drug-eluting stents (DES) for preventing intimal hyperplasia. Previously, we found that 5-aminolevulinic acid-mediated sonodynamic therapy (ALA-SDT) suppressed macrophage-mediated inflammation in atherosclerotic plaques. However, the effects on intimal hyperplasia and re-endothelialization remain unknown. In this study, 56 rabbits were randomly assigned to control, ultrasound, ALA and ALA-SDT groups, and each group was divided into two subgroups (n = 7) on day 3 after right femoral artery balloon denudation combined with a hypercholesterolemic diet. Histopathological analysis revealed that ALA-SDT enhanced macrophage apoptosis and ameliorated inflammation from day 1. ALA-SDT inhibited neointima formation without affecting re-endothelialization, increased blood perfusion, decreased the content of macrophages, proliferating smooth muscle cells (SMCs) and collagen but increased elastin by day 28. In vitro, ALA-SDT induced macrophage apoptosis and reduced TNF-α, IL-6 and IL-1β via the ROS-PPARγ-NF-κB signalling pathway, which indirectly inhibited human umbilical artery smooth muscle cell (HUASMC) proliferation, migration and IL-6 production. ALA-SDT effectively inhibits intimal hyperplasia without affecting re-endothelialization. Hence, its clinical application combined with bare-metal stent (BMS) implantation presents a potential strategy to decrease bleeding risk caused by prolonged dual-antiplatelet regimen after DES deployment.

The Use of Fractional Flow Reserve for Physiological Assessment of Indeterminate Lesions in Peripheral Artery Disease

Peripheral artery disease (PAD) is a prevalent disorder in the United States, associated with significant morbidity and mortality. Fractional Flow Reserve (FFR) is a physiological test used to assess the hemodynamic significance of intermediate lesions on conventional angiography. It is well studied in coronary artery disease and is as an important tool to guide decisions regarding revascularization in a significant percentage of patients with intermediate lesions. As compared to coronary FFR, the use of FFR in peripheral artery disease (PFFR) is much less prevalent. Overall data regarding the use of the PFFR is sparse. There are limited studies that have shown the correlation of PFFR with non-invasive testing including ankle-brachial index (ABI) and Doppler Imaging. Unlike coronary FFR, the optimal pharmaceutical agents and doses to induce maximal hyperemia in the peripheral vascular bed are also not well established. Moreover, there are no established standardized procedural protocols for measuring PFFR. Various studies have employed varying techniques, hyperemic agents and doses. The aim of this literature review is to summarize the current evidence on PFFR, the correlation with noninvasive studies used in PAD and to increase awareness of the potential role of the PFFR in peripheral interventions.

Fractional flow reserve in below the knee arteries with critical limb ischemia and validation against gold-standard morphologic, functional measures and long term clinical outcomes

INTRODUCTION

The aim of this study was to assess the applicability of fractional flow reserve measurement (FFR) in below-the-knee (BTK) arteries and to evaluate its correlation with non-invasive functional parameters before and after angioplasty.

METHODS

We enrolled 39 patients with severe BTK arterial lesions. Inclusion criteria were critical limb ischemia (Rutherford 4-6) and angiographically proven arterial stenosis of the distal lower limb (percent diameter stenosis ≥70%). Exclusion criteria were chronic total occlusion, diabetic foot syndrome and non-viable distal lower limb. The transstenotic distal/proximal pressure ratio was measured under resting (Pd/Pa) and hyperemic (FFR) conditions induced by 40mg intra-arterial Papaverin and was compared with quantitative angiography-, laser Doppler- and duplex ultrasound-derived measurements before and after percutaneous angioplasty (PTA).

RESULTS

Comparing measurements before and after PTA, we found significant improvements in the resting Pd/Pa values (0.79 [0.67-0.90] vs 0.90 [0.85-0.97]; p<0.001) and FFR values (0.60±0.19 vs 0.76±0.15; p<0.001), respectively. At baseline, Pd/Pa ratio and FFR were significantly albeit weakly correlated with % area stenosis (r:-0.31, p=0.05 and r:-0.31, p=0.05, respectively). After PTA, neither Pd/Pa nor FFR remained correlated with % area stenosis. Similarly, prior PTA, Pd/Pa ratio and FFR were significantly correlated with TcO2% and perfusion unit change (r:0.48, p<0.01 and r:0.34, p<0.05, respectively), but after intervention, these significant correlations vanished. Pd/Pa and FFR values did not show correlation with duplex ultrasound-derived measurements. At 1year, major adverse events (MAEs) and major adverse cardiovascular and cerebrovascular (MACCEs) were observed in 7 (17.9%) and in 9 (23.1%) patients, respectively.

CONCLUSION

CLI due to severe BTK arterial disease was associated with several impediments of baseline pressure measurements which were significantly improved after successful PTA and stenting. Significant relationships between pressure data and functional and imaging parameters existed prior intervention but vanished after. Further studies are required to determine the clinical value of pre- and post-PTA pressure measurements in BTK arterial disease.

How to define the hemodynamic significance of an equivocal iliofemoral artery stenosis: Review of literature and outcomes of an international questionnaire

Purpose

The goal of the study was to review current literature regarding the diagnosis of equivocal (50–70%) iliofemoral artery stenosis and compare these findings with the daily practice of an international panel of endovascular experts.

Methods

The Medline Database was searched for relevant publications, and an electronic survey was sent to experts in the field covering the following topics: definition of an equivocal iliofemoral artery stenosis, angiographic visualization and investigation protocols of an equivocal stenosis, intra-arterial pressure measurements, and definition of hemodynamic significance of an equivocal iliofemoral artery stenosis using a physiologic measure.

Results

Of the 37 invited endovascular experts, 21 (53.8%) agreed to participate in the survey. Analysis of existing literature shows that the level of evidence for diagnosing equivocal iliofemoral artery stenosis is mediocre and is not being implemented by experts in the field.

Conclusion

Studies have shown that a stenosis of between 50% and 70% iliofemoral lumen diameter reduction shows a wide range of trans-stenotic pressure gradients. Equivocal iliofemoral artery stenosis can best be identified using three-dimensional quantitative vascular analysis software. Although evidence for a clear hemodynamic cutoff point is weak, performing trans-lesion intra-arterial pressure measurements at rest and during maximal hyperemia is preferred. Diagnosing iliofemoral artery stenosis solely on lumen diameter reduction is inadequate.

Ability of Fractional Flow Reserve to Predict Restenosis After Superficial Femoral Artery Stenting

PURPOSE

To evaluate the clinical efficacy of poststenting fractional flow reserve (FFR) in terms of predicting restenosis in superficial femoral artery (SFA) disease.

METHODS

This prospective, single-center, nonrandomized study enrolled 48 patients (mean age 76±9 years; 38 men) with 51 SFA lesions from July 2013 to June 2014. Mean FFR (distal mean pressure/proximal mean pressure) and systolic FFR (distal systolic pressure/proximal systolic pressure) were calculated, and the relationship between these FFR values and restenosis at 12 months was investigated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Poststenting FFR was significantly lower in the restenosis group (poststenting mean FFR 0.85±0.07 vs 0.93±0.05, p=0.001; poststenting systolic FFR 0.76±0.14 vs 0.87±0.08, p=0.015). The area under the ROC curve for restenosis in poststenting mean FFR was higher, but not statistically significant, than that in poststenting systolic FFR (0.84 vs 0.74, p=0.08). The best poststenting mean FFR cutoff value for predicting restenosis was 0.92 (sensitivity 0.64, specificity 0.91). The 4.5% restenosis rate at 12 months in the high (>0.92) poststenting mean FFR group was significantly lower (35.7%, p=0.008) than in the low (≤0.92) poststenting mean FFR group.

CONCLUSION

Poststenting mean FFR is useful for predicting restenosis in SFA disease.

Computed Tomography Fractional Flow Reserve Can Identify Culprit Lesions in Aortoiliac Occlusive Disease Using Minimally Invasive Techniques

BACKGROUND

Currently, the gold standard diagnostic examination for significant aortoiliac lesions is angiography. Fractional flow reserve (FFR) has a growing body of literature in coronary artery disease as a minimally invasive diagnostic procedure. Improvements in numerical hemodynamics have allowed for an accurate and minimally invasive approach to estimating FFR, utilizing cross-sectional imaging. We aim to demonstrate a similar approach to aortoiliac occlusive disease (AIOD).

METHODS

A retrospective review evaluated 7 patients with claudication and cross-sectional imaging showing AIOD. FFR was subsequently measured during conventional angiogram with pull-back pressures in a retrograde fashion. To estimate computed tomography (CT) FFR, CT angiography (CTA) image data were analyzed using the SimVascular software suite to create a computational fluid dynamics model of the aortoiliac system. Inlet flow conditions were derived based on cardiac output, while 3-element Windkessel outlet boundary conditions were optimized to match the expected systolic and diastolic pressures, with outlet resistance distributed based on Murray's law. The data were evaluated with a Student's t-test and receiver operating characteristic curve.

RESULTS

All patients had evidence of AIOD on CT and FFR was successfully measured during angiography. The modeled data were found to have high sensitivity and specificity between the measured and CT FFR (P = 0.986, area under the curve = 1). The average difference between the measured and calculated FFRs was 0.136, with a range from 0.03 to 0.30.

CONCLUSIONS

CT FFR successfully identified aortoiliac lesions with significant pressure drops that were identified with angiographically measured FFR. CT FFR has the potential to provide a minimally invasive approach to identify flow-limiting stenosis for AIOD.

Validation of pressure gradient and peripheral fractional flow reserve measured by a pressure wire for diagnosis of iliofemoral artery disease with intermediate stenosis

Objective

To examine the pressure gradient and peripheral fractional flow reserve (pFFR) measured by a pressure wire as indicators of hemodynamic significance in iliofemoral angiographic intermediate stenosis.

Background

The utility of pressure measurements using a pressure wire with vasodilators is unclear in cases with intermediate iliofemoral stenosis.

Methods

The mean pressure gradient (MPG) and mean pressure ratio (MPR) were measured at baseline and after injection of isosorbide dinitrate in 23 lesions with angiographically intermediate iliofemoral stenosis. Patients with complex lesions, infrapopliteal artery lesions, chronic total occlusion, and surgical bypass grafts were excluded. Hyperemic MPR was considered equivalent to pFFR. Changes in parameters in response to vasodilators were assessed and correlations of peak systolic velocity ratio (PSVR) with hyperemic MPG and pFFR were examined using duplex ultrasound.

Results

After injection of isosorbide dinitrate, hyperemic MPG increased significantly (from 9.0±5.7 to 16.3±6.2 mmHg; P<0.05) and hyperemic MPR (pFFR) decreased significantly (from 0.92±0.06 to 0.81±0.07; P<0.05). PSVR was significantly correlated with hyperemic MPG (R=0.52; P<0.05) and pFFR (R=−0.50; P<0.05). The optimal cut-off value of pFFR as an indicator of significant hemodynamic stenosis (PSVR >2.5) was 0.85 (area under the curve 0.72; sensitivity 94%; specificity 50%, P<0.05).

Conclusion

pFFR measured using a pressure wire is reliable for prediction of hemodynamic significance in iliofemoral intermediate stenosis.

Measuring Procedure and Maximal Hyperemia in the Assessment of Fractional Flow Reserve for Superficial Femoral Artery Disease

AIM

The optimal fractional flow reserve (FFR) measurement method for superficial femoral artery (SFA) lesions remains to be established. We clarified the optimal measuring procedure for FFR for SFA lesions and investigated the necessary dose of papaverine for inducing maximal hyperemia in SFA lesions.

METHODS

Forty-eight patients with SFA lesions who underwent measurement of peripheral FFR (pFFR: distal mean pressure divided by proximal mean pressure) after endovascular treatment by the contralateral femoral crossover approach were prospectively enrolled. In the pFFR measurement, a guide sheath was placed on top of the common iliac bifurcation and pressure equalization was performed. After advancing the pressure wire distal to the SFA lesion, sequential papaverine administration selectively to the affected common iliac artery was performed.

RESULTS

There were no symptoms, electrocardiogram changes, and significant pressure drops at the guide sheath tip with increasing papaverine dose. pFFR changes following 20, 30, and 40 mg of papaverine were 0.87±0.10, 0.84±0.10, and 0.84±0.10, respectively (P＜0.001). Although not significantly different, pFFR decreased more in several patients at 30 mg of papaverine than at 20 mg. The pFFR at 40 mg of papaverine was almost similar to that at 30 mg of papaverine. The necessary papaverine dose was not changed according to sex and number of run-off vessels.

CONCLUSIONS

The contralateral femoral crossover approach is useful in FFR measurement for SFA lesions, and maximal hyperemia is induced by 30 mg of papaverine.

Pathogenesis of the limb manifestations and exercise limitations in peripheral artery disease

Patients with peripheral artery disease have a marked reduction in exercise performance and daily ambulatory activity irrespective of their limb symptoms of classic or atypical claudication. This review will evaluate the multiple pathophysiologic mechanisms underlying the exercise impairment in peripheral artery disease based on an evaluation of the current literature and research performed by the authors. Peripheral artery disease results in atherosclerotic obstructions in the major conduit arteries supplying the lower extremities. This arterial disease process impairs the supply of oxygen and metabolic substrates needed to match the metabolic demand generated by active skeletal muscle during walking exercise. However, the hemodynamic impairment associated with the occlusive disease process does not fully account for the reduced exercise impairment, indicating that additional pathophysiologic mechanisms contribute to the limb manifestations. These mechanisms include a cascade of pathophysiological responses during exercise-induced ischemia and reperfusion at rest that are associated with endothelial dysfunction, oxidant stress, inflammation, and muscle metabolic abnormalities that provide opportunities for targeted therapeutic interventions to address the complex pathophysiology of the exercise impairment in peripheral artery disease.

Diagnostic value of peripheral fractional flow reserve in isolated iliac artery stenosis: a comparison with the post-exercise ankle-brachial index

PURPOSE

To examine in claudicant patients with aortoiliac lesions the relationship between the post-exercise ankle-brachial index (ABI) and the peripheral fractional flow reserve (p-FFR), a physiological test that has heretofore been used to assess coronary and renal artery stenosis.

METHODS

Sixteen male patients (mean age 68.1±7.5 years) with isolated iliac artery lesions detected by ultrasound in 17 limbs were enrolled in this study. Resting ABI was measured and a treadmill test was administered to measure the post-exercise ABI. During angiography, the p-FFR was measured using a pressure guidewire after administration of papaverine to induce hyperemia. Changes in the ABI during exercise and p-FFR at hyperemia were calculated.

RESULTS

The mean resting ABI and post-exercise ABI were 0.87±0.12 and 0.65±0.24, respectively. There was no complication during the measurement of p-FFR. The mean p-FFR at hyperemia was 0.71±0.14. A significant linear correlation was observed between post-exercise ABI and p-FFR at hyperemia (r=0.857, p<0.001), which was stronger than the correlation between post-exercise ABI and peak-to-peak pressure gradient at hyperemia (r= -0.626, p=0.013).

CONCLUSIONS

Measuring p-FFR appears to be a feasible and safe procedure, and there is a significant linear correlation between post-exercise ABI and p-FFR in aortoiliac lesions. The p-FFR was more accurate than a peak-to-peak pressure gradient in assessing the physiological significance of a stenosis. Though larger studies are required, p-FFR might be used to physiologically assess stenosis in PAD patients with isolated aortoiliac lesions.