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

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.

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.

Retrograde branched extension limb assembling stent of pararenal abdominal aortic aneurysm: A longitudinal hemodynamic analysis for stent graft migration

PURPOSE

Pararenal abdominal aortic aneurysms (PRAAAs) are a life-threatening disease, and hemodynamic analysis may provide greater insight into the effectiveness and long-term outcomes of endovascular aneurysm repair (EVAR). However, the lack of patient-specific boundary conditions on the periphery compromises the accuracy. Windkessel (WK) boundary conditions coupled to hemodynamic follow-up models of a PRAAA patient, aims to provide insights into the link between hemodynamics and poor prognosis.

METHOD

One PRAAA patient underwent EVAR and reintervention after one branch of stent-graft (SG) had migrated. Totally five computational follow-up models were studied. Patient-specific flow data acquired via ultrasound were used to define the boundary conditions in the ascending aorta and the following three branches. Coupled zero-dimensional WK models representing the distal vasculature were used to define the outlet boundary conditions under the abdomen.

RESULTS

Flow divisions of the main SG branches were 40.7% and 24.7%, respectively. Time-averaged wall shear stress and oscillatory shear index (OSI) increased at the junction connected the SG branch and the stent leading to the right common iliac artery (RCIA) where the stent migrated. The OSI and relative residence time (RRT) value in superior mesenteric artery increased notably after the migration, the RRT continuously increased following the reintervention.

CONCLUSION

Unbalanced flow, resulting in locally high-speed flow, high WSS and OSI might significantly affect stent stability. Results suggest that diameters and interconnection design of stents in complex cases should take the flow division into consideration and computational simulations might be considered as a tool for intervention protocol design.

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.

Functional Assessment of Intermediate Vascular Disease

Interventional treatment in various vascular beds has advanced tremendously. However, there are several problems to be considered. We searched the literature and tried to analyze major parts of it. One is safety and applicability of coronary proven methods in other vascular beds. An unresolved problem is the functional assessment of intermediate lesions, as far as various target organs have quite different circulation from the coronary one and the functional tests should be modified in order to be applicable and meaningful. In the majority of the acute vascular syndromes, the culprit lesion is of intermediate size on visual assessment. On the other hand, a procedurally successfully managed high-degree stenosis is not always followed by clinical and prognostic benefit. In vascular beds, where collateral network naturally exists, the readings from the functional assessment are complicated and thus the decision for interventional treatment is even more difficult. Here come into help the functional assessment and imaging with IVUS, OCT, high-resolution MRI, and contrast enhanced CT or SPECT. The focus of the current review is on the functional assessment of intermediate stenosis in other vascular beds, unlike the coronary arteries.

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.