The role of duplex scanning in the diagnosis of lower limb arterial disease

Peak systolic velocity ratio derived from quantitative vessel analysis for restenosis after femoropopliteal intervention: a multidisciplinary review from Endovascular Asia

With technological improvements in the endovascular armamentarium, there have been tremendous advances in catheter-based femoropopliteal artery intervention during the last decade. However, standardization of the methodology for assessing outcomes has been underappreciated, and unvalidated peak systolic velocity ratios (PSVRs) of 2.0, 2.4, and 2.5 on duplex ultrasonography have been arbitrarily but routinely used for assessing restenosis. Quantitative vessel analysis (QVA) is a widely accepted method to identify restenosis in a broad spectrum of cardiovascular interventions, and PSVR needs to be validated by QVA. This multidisciplinary review is intended to disseminate the importance of QVA and a validated PSVR based on QVA for binary restenosis in contemporary femoropopliteal intervention.

Optimal Ultrasound Criteria for Grading Stenosis of the Superficial Femoral Artery

This retrospective study determined the duplex ultrasound scanning criteria for detecting 50%-69% and 70%-99% stenosis of the superficial femoral artery (SFA). Examinations of 278 limbs in 185 patients with peripheral arterial disease were performed. Duplex ultrasound scanning was used to measure the diameter of the vascular lumen, the peak systolic velocity (PSV) at the stenotic segment of the SFA (PSV_st), the segment proximal to the stenosis (PSV_pro) and the popliteal artery (PSV_pop, distal to the stenosis). The ratios PSV_st/PSV_pro and PSV_st/PSV_pop were calculated. Receiver operator characteristic curves were plotted, with digital subtraction angiography as the reference. PSV_st and PSV_st/PSV_pop had the highest diagnostic value for stenosis. Cut-off thresholds were: for 50%-69% stenosis, PSV_st ≥ 210 cm/s, PSV_st/PSV_pop ≥ 2.5, with PSV_st the better parameter; for 70%-99% stenosis, PSV_st ≥ 275 cm/s, PSV_st/PSV_pop ≥ 4.0, with PSV_st/PSV_pop superior. PSV_st/PSV_pop may be a better parameter than PSV_st/PSV_pro for diagnosing SFA stenosis.

Characteristics of peripheral arterial disease and its relevance to the diabetic population

Peripheral arterial disease (PAD) is very frequent in diabetics, and it increases with age. Foot examination contributes poorly to diagnosis of PAD. The ankle-brachial index (ABI) measurement is considered the most accurate noninvasive diagnostic method when evaluating PAD: ABI evaluation is recommended in all diabetics aged >50 years. Many diabetic patients with PAD have a concomitant sensitive neuropathy: as a consequence, perception of ischemic pain is remarkably reduced or completely blocked. The result is that the prevalence of claudication in the diabetic population with PAD is lower than the prevalence of critical limb ischemia (CLI) in this population. CLI is a major risk factor for lower extremity amputation without revascularization. Ankle and toe pressures and oxygen tension at the foot are the noninvasive diagnostic parameters of CLI though the medial artery calcification inhibits accurate determination of the ankle and toe pressures, especially when a forefoot ulcer is present. In diabetics, the anatomical localization is mainly distal; arterial wall calcification is frequently observed and occlusion occurs more frequently than stenosis. Such anatomical features, along with the difficulties in the diagnostic approach, account for the fundamental role of CLI as the main prognostic indicator for major amputation. PAD is an expression of systemic atherosclerotic disease. Prognosis of patients with PAD is related to the presence and extent of underlying coronary artery disease (CAD) but also to the severity of PAD: in particular, patients in whom revascularization is not feasible have the highest mortality rate.

The Results of High-Frequency Duplex Surveillance After Iliac Arterial Stenting in a Single Center

Frequent duplex surveillance after iliac arterial stenting is time-consuming and costly, so solid benefits of this approach must be available. Frequent duplex surveillance was performed at our center, this was reviewed retrospectively.A total of 117 stents were assessed. Duplex was done for 84 (71.8%) of 117 patients at 1 year and 25 (21.4%) of 117 at 5 years, mean follow-up 27.6 months. Totally, 456 scans were performed; 386 (84.6%) scans were normal, 43 (9.4%) showed an abnormality for which intervention was not necessary, 27 (5.9%) showed abnormalities which needed interventions. The maximum attendance of patients was 62%. In all, 18 patients had interventions unrelated to scheduled follow-up; 15 (83.3%) of 18 had no prior abnormalities on duplex, 3 (16.6%) of 18 had prior abnormalities which were not acted upon after clinical assessment. Our findings demonstrate a high nonattendance rate with frequent emergency presentations due to acute complications. We cannot, therefore, recommend frequent duplex surveillance program both in terms of results or resource allocation.

Cost-effectiveness of identifying aortoiliac and femoropopliteal arterial disease with angiography or duplex scanning

OBJECTIVES

Cost-effectiveness analysis of three diagnostic imaging strategies for the assessment of aortoiliac and femoropopliteal arteries in patients with peripheral arterial occlusive disease. The strategies were: angiography as the reference strategy, duplex scanning (DS) plus supplementary angiography (S1) and DS plus confirmative angiography (S2).

DESIGN, MATERIALS AND METHODS

A decision model was built with sensitivity and specificity data from literature, supplemented with prospective hospital cost data in Euro (euro). The probability of correctly identifying the status of a lesion was taken as the primary outcome. We compared strategies by assessing the extra costs per additional correctly identified case.

RESULTS

Assuming no false positive or false negative results, angiography is the most effective strategy if the prevalence of significant obstructive lesions in the aortoiliac and femoropopliteal tract exceeds 70%, or if the sensitivity of duplex scanning is lower than 83%. In case of lower prevalence, strategy S1 becomes equally or even more effective than angiography. At a prevalence of 75%, performing angiography costs euro 8443 per extra correctly identified case compared with strategy S1.

CONCLUSIONS

In most situations angiography is more effective than diagnostic strategy S1. However, if society is unwilling to pay more than euro 8443 for knowing a patient's disease status, diagnostic strategy S1 is a cost-effective alternative to angiography, especially at lower prevalence values.

Diagnostic value of carotid intima-media thickness in indicating multi-level atherosclerosis

Carotid intima-media thickness (CIMT) is an indicator of atherosclerosis, but its association with multi-level involvement is sparsely investigated. Study aimed to examine interrelation between CIMT and number of arterial territories with significant (>50%) stenoses, including coronary, supraaortic, renal and iliac/femoral arteries.

METHODS AND RESULTS

Study formed 415 patients (294 men), aged 62.9+/-9.3 years referred to coronary angiography. CIMT assessment was performed in common, bulb and internal carotid segments, and expressed as the mean aggregate value. In all patients, both coronary, renal angiography and supraaortic, iliac/femoral arteries ultrasound was performed. Group I formed 102 patients without significant lesions in any of investigated territories; group II formed 131 patients with single territory; group III formed 102 patients with two territory and group IV formed 80 patients with three to four territory involvements. CIMT correlated with increasing number of involved territories (r=0.751, p<0.001). Aggregate CIMT, previous myocardial infarction, creatinine level, hypertension, hs-CRP, smoking were independent predictors of multi-level involvement (p<0.001, R=0.768). ROC curves showed that CIMT cut-off value of 1.308 mm could distinguish 0-1 from two to three level involvement with sensitivity of 81.6%, specificity 88.8%, PPV 85.1%, NPV 86.3% (odds ratio 35.9, range 20-65).

CONCLUSIONS

CIMT increases with number of involved territories. CIMT is an independent predictor of significant multi-level atherosclerosis, showing high sensitivity and specificity for indicating more advanced territorial atherosclerotic involvement.

Influence of multiple stenoses on echo-Doppler functional diagnosis of peripheral arterial disease: a numerical and experimental study

The objective of this paper was to evaluate the ability of the peak systolic velocity ratio (PSVR) and pressure drop (DeltaP) to detect and grade multiple stenoses in lower limb mimicking arteries. Numerical simulations and experiments in vascular phantoms allowing ultrasound duplex scanning and pressure measurements were used to investigate simple and double stenotic arterial segments. Inter-stenotic distance, severity of the distal stenosis, flow rate and flow profile (steady or pulsatile) were the tested parameters. The three-dimensional simulations considered the turbulent two-equation Wilcox model. Agreements were observed between the experimental and numerical results for DeltaP and PSVR. The maximum PSVR along the artery was shown to be mainly influenced by the severity of the most important stenosis. However, mutual interactions of both stenoses on hemodynamics were noted. By using the clinical PSVR threshold used to diagnose critical lesions (PSVR > or = 2), its longitudinal evolution along the artery poorly reflected the length of the lesion or the impact of surrounding stenoses. This investigation confirms the interaction between adjacent stenoses on hemodynamics and its impact on the Doppler ultrasound index PSVR.

Ultrasound contrast-agent improves imaging of lower limb occlusive disease

OBJECTIVES

to evaluate if ultrasound contrast-agent infusion could improve duplex-ultrasound imaging of peripheral arterial disease (PAD) and increase the agreement with digital subtraction arteriography (DSA).

DESIGN

prospective and consecutive study.

MATERIAL

of 60 consecutive PAD patients, 15 were found to have an inconclusive duplex-ultrasound scan of the trifurcation and were included in the study. All 15 patients (53% male) were scheduled for DSA, all being candidates for vascular surgery due to claudication (n = 3, 20%), rest pain (n = 5, 33%) and tissue loss (n = 7, 47%).

METHODS

on the day before DSA, a duplex-ultrasound scan of the trifurcation was performed. If the duplex-ultrasound scan was found inconclusive, it was repeated during continuous ultrasound contrast-agent infusion. DSA was performed unaware of the duplex-ultrasound results and served as the gold standard.

RESULTS

after contrast-agent administration, the number of inconclusively diagnosed segments was significantly reduced by 26 (70%), from 37 to 11(p < 0.001). In 19 segments (73%) contrast-agent infusion changed the diagnosis in accordance with the DSA (p < 0.05). Values of sensitivity and positive predictive value were improved from 0.20 (0.04-0.62) to 0.47 (0.26-0.69) and 0.50 (0.10-0.91) to 0.80 (0.49-0.93), respectively. Specificity and negative predictive value were unchanged. Agreement between duplex-ultrasound and DSA were improved from poor (kappa = 0.18 (95% CI: 0-0.82)) to moderate (kappa = 0.45 (0.17-0.74)) (p = 0.44).

CONCLUSION

ultrasound contrast-agents improve the diagnostic ability of duplex-ultrasound when scanning difficult arterial segments in patients suffering from PAD.

The additional value of angiography after colour-coded duplex on decision making in patients with critical limb ischaemia. A prospective study

OBJECTIVE

to investigate prospectively the additional value of intra arterial digital subtraction arteriography (IADSA) for decision making in patients with critical limb ischemia (CLI). Treatment plans based on colour-duplex imaging (CDI) were compared with treatment plans based on IADSA.

METHODS

ninety-eight consecutive patients with 112 legs with CLI were investigated by CDI and IADSA. Treatment plans based on CDI and IADSA were made separately during a multidisciplinary meeting. Both plans were retrospectively analysed with the outcome of the operation or the endovascular procedure as a reference.

RESULTS

eighty-eight patients with 101 legs could be analysed. In 91 out of the 101 legs (90%) CDI offered the same strategy as the IADSA. In 10 legs IADSA provided additional information. Most of the additional information concerned the crural vessels.

CONCLUSION

the preoperative planning of treatment in patients with chronic critical ischaemia of the lower limbs can be based on CDI alone in most patients. For planning crural revascularisation additional information may be needed. If severe calcification prevents adequate visualisation of the crural vessels or no patent anterior or posterior tibial artery with outflow across the ankle is present, IADSA should be performed.

Screening for aortoiliac lesions by visual interpretation of the common femoral Doppler waveform

OBJECTIVE

to study the accuracy of simple visual interpretation of the common femoral artery Doppler waveform for screening the aorto-iliac segment for significant occlusive disease.

DESIGN

prospective and semi-blinded study. Material ninety-four consecutive and elective patients having arteriography due to chronic lower limb ischaemia, presenting symptoms of severe claudication (23%), ischaemic rest pain (34%) or ischaemic skin lesions (43%).

METHODS

one day prior to conventional arteriography a Doppler waveform was obtained in the common femoral artery. Based on visual interpretation, the waveforms were immediately categorised as normal or abnormal. Comparison with single plane arteriography with respect to significant aorto-iliac occlusive disease was undertaken.

RESULTS

visual Doppler waveform interpretation had a sensitivity of 98% (95% CI: 90-100%), a specificity of 81% (CI: 67-90%), a positive predictive value of 86% (CI: 75-93%) and a negative predictive value of 97% (CI: 86-100%) for prediction of significant aorto-iliac occlusive disease using conventional arteriography as the gold standard. The kappa value for the agreement between Doppler waveform interpretation and arteriography was 0.81 (0.68-0.93), representing very good agreement.

CONCLUSION

a normal common femoral Doppler waveform can safely exclude significant upstream aorto-iliac lesions and is a useful timesaving screening tool in the busy vascular laboratory. The method is well tolerated, easy to perform and requires no additional equipment.

The role of duplex scanning in decision making for patients with claudication

The aim of this study was to compare the accuracy of clinical decisions made for patients presenting with claudication on the basis of the ankle/brachial index (ABI) (at rest and postexercise) and duplex scanning with that made on the basis of angiograms. Fifty-six patients presenting with a history suggestive of claudication had the ABI taken at rest. Seven patients could not be exercised but their resting ABI was <0.8. Additional exercise testing was done in 49 patients; two were then excluded as there was no fall in the ABI. Thus, 54 patients were entered into the study and underwent color-flow duplex scans and angiography. A clinical decision was reached independently on the basis of the results of ABI and duplex scans as to a) conservative treatment, b) angioplasty, and c) surgery. This was compared to the decision reached on the basis of angiograms. The results show that the combined use of ABI (as a screening test) and duplex scanning can replace angiography for clinical decision making in nearly 80% of claudicants. Angiography will only be needed when duplex scans are inconclusive.