Colour-coded duplex imaging and dependent ... - IngentaConnect

Original article

Colour-coded duplex imaging and dependent Doppler ultrasonography in the assessment of cruropedal vessels M. J. McCarthy, S. Nydahl, T. Hartshorne, A. R. Naylor, P. R. F. Bell and N. J. M. London Department of Surgery, Robert Kilpatrick Clinical Science Building, University of Leicester, Leicester LE2 7LX, UK Correspondence to: Mr M. J. McCarthy

Background: It has been suggested that ultrasonography could replace diagnostic arteriography in the assessment of patients who present with leg ischaemia. This study investigated a group of consecutive patients who had femorodistal bypass and who were assessed before operation with colour-coded duplex and dependent Doppler insonation alone. Methods: Thirty-seven consecutive patients with critical lower limb ischaemia underwent surgical exploration with a view to femorodistal bypass. Results of preoperative colour-coded duplex and dependent Doppler insonation were compared with intraoperative arteriograms and surgical ®ndings. Results: There was very good agreement between colour-coded duplex imaging and dependent Doppler insonation with intraoperative angiography and surgical ®ndings in the prediction of the optimal run-off vessel (j 1á0) and the site of the distal anastomosis (j 0á85; 95 per cent con®dence interval 0á71±1á0). There was also very good agreement between dependent Doppler insonation and intraoperative arteriography (j 1á0) in predicting pedal arch patency and the predominant feeding vessel. Conclusion: Assessment of leg arteries before femorodistal bypass can be performed accurately with non-invasive colour-coded duplex imaging and dependent Doppler insonation alone, thus obviating the need for preoperative arteriography.

Paper accepted 18 July 1998

Introduction

British Journal of Surgery 1999, 86, 33±37

imaging and dependent Doppler insonation of the pedal arch alone could predict the best run-off vessel, the site of distal graft anastomosis, pedal arch patency and identify the vessel supplying the arch. The results of preoperative assessment were compared with those obtained with intraoperative angiography.

Identifying patent run-off vessels and demonstrating pedal arch patency before femorocrural bypass is essential to maximize graft patency and limb salvage rates1. The accepted `gold standard' for preoperative assessment of the infrapopliteal vessels is intra-arterial digital subtraction arteriography. Advocates of less invasive and cheaper methods of preoperative imaging, such as pulse-generated run-off2,3, colour-coded duplex imaging4±6 and dependent Doppler examination7±9, have stated that these methods are as good as, if not better than, angiography. The major advantage of colour duplex imaging and dependent Doppler examination is that they provide both anatomical and haemodynamic information. Lower limb vascular reconstruction can be performed successfully by means of preoperative colour-coded duplex imaging alone10. Colour duplex ultrasonography is comparable to arteriography for imaging infrapopliteal arteries6 and could supersede arteriography11. The aim of this study was to investigate whether colour-coded duplex

Over a 15-month interval, 283 legs in 247 patients presented with critical lower limb ischaemia as de®ned by the European Consensus Document12. All patients were assessed by means of colour-coded duplex imaging and dependent Doppler ultrasonography. If the arterial lesions demonstrated were thought suitable for angioplasty, then this was planned with the interventional radiologists. In all, 128 legs (45 per cent) were managed by percutaneous transluminal angioplasty (PTA), 24 (8 per cent) had a major primary amputation, 50 (18 per cent) had conservative treatment and 81 (29 per cent) had limb salvage surgery. From this cohort, 37 consecutive patients (37

Ó 1999 Blackwell Science Ltd


Patients and methods

33

34

Assessment of leg ischaemia M. J. McCarthy, S. Nydahl, T. Hartshorne et al.

legs) were considered for femorocrural bypass and were entered into the study. Eighteen had ischaemic rest pain alone, 19 had additional skin necrosis. There were 24 men and 13 women, with a median (range) age of 71 (49± 93) years. Eight patients had diabetes mellitus. All patients were assessed before operation using colour-coded duplex imaging to identify patent crural vessels and dependent Doppler insonation of the ankle and pedal vessels to assess pedal arch patency. Dependent Doppler ultrasonography Dependent Doppler insonation of all three crural vessels at the ankle was performed with an 8-MHz pencil probe. The probe was used to identify the presence of signals in the posterior tibial, anterior tibial/dorsalis pedis, peroneal and lateral plantar arteries. Ankle systolic pressure was measured in the supine position. The pedal arch was presumed to be patent when a signal was present in the ®rst metatarsal space over the area of the deep plantar artery. Individual tibial artery compression was performed while listening to the pedal arch signal to determine which crural vessel was the major vessel supplying the arch. Colour-coded duplex ultrasonography An ATL HDI Ultramark 9 or a Diasonics Spectra (Diasonics, Bedford, UK) ultrasound machine was used. Imaging was performed from the aortic bifurcation to the cruropedal vessels. If an in¯ow vessel had a stenosis with a velocity increase greater than 2á0, PTA was arranged before surgical reconstruction. Infrapopliteal vessels were visualized with a 5-MHz probe5. Intraoperative arteriography At operation, a medial calf incision was performed through which the below-knee popliteal artery and tibioperoneal trunk were exposed. Intraoperative arteriography was performed by inserting a 15-G butter¯y needle into the below-knee popliteal artery and then injecting 20 ml of contrast13. Arteriography was achieved by this method in 13 patients. If the popliteal artery was occluded, arteriography was performed via the tibioperoneal trunk (ten legs) or a patent proximal crural artery, as judged by the preoperative duplex image. The arteriogram was then used to identify the most suitable vessel for distal anastomosis. When the arteriogram failed to demonstrate a patent crural vessel in the calf, all ankle vessels were explored (seven legs). The vessels were opened and, if the lumen was patent, arteriography was performed; if no patent vessel running into the foot could be identi®ed, the British Journal of Surgery 1999, 86, 33±37

leg was amputated. All patients had completion arteriography via the vein graft. Statistical analysis The preoperative colour-coded duplex and dependent Doppler ultrasonographic results were compared with the intraoperative arteriograms and surgical ®ndings by means of the kappa (j) statistic. j < 0á2 represented a poor agreement between the tests, a value between 0á21 and 0á40 a fair agreement, 0á41±0á60 represented a moderate agreement, 0á61±0á80 a good agreement, and 0á81±1á0 a very good agreement. Three distinct comparisons were made to elucidate whether colour-coded duplex imaging and dependent Doppler insonation alone could predict (1) the best runoff vessel, (2) the predominant vessel supplying the pedal arch, and (3) the level of the distal anastomosis. The crural vessels were de®ned as tibioperoneal trunk, anterior tibial artery, posterior tibial artery and the peroneal artery; each artery was divided into upper, middle and lower thirds. Primary, primary assisted and secondary graft patency rates were generated using the Kaplan-Meier survival statistic on SPSS (Chicago, Illinois, USA) for the Power Macintosh (Apple, Crawley, UK). Results

The median (range) time taken to perform initial duplex and Doppler ultrasonographic studies was 30 (20± 60) min. Based on the duplex ®ndings 19 patients were referred for angioplasty. Four patients had a successful in¯ow angioplasty before femorocrural bypass and six had failed recanalization of a long occlusion of the femoropopliteal segment; nine were found unsuitable for angioplasty because of diffuse atheroma and heavy calci®cation of vessels. The day before surgery all 37 patients underwent repeat duplex imaging and dependent Doppler insonation. At this time all suitable veins were marked on the skin by the vascular technologist together with a suggested site for the distal anastomosis. Thirty-four infrainguinal grafts were performed (Table 1). In three legs, no patent cruropedal vessels were identi®ed and these patients underwent primary below-knee amputation. There was very good agreement between colour-coded duplex and dependent Doppler studies in prediction of the most suitable vessel for distal anastomosis as identi®ed at operation (j 1á0) (Table 2). Colour-coded duplex imaging was also able to predict, with very good agreement (j 0á85 (95 per cent con®dence interval 0á71±1á0)), the site at which the anastomosis took place Ó 1999 Blackwell Science Ltd

M. J. McCarthy, S. Nydahl, T. Hartshorne et al. Assessment of leg ischaemia 35

Site of distal anastomosis Posterior tibial artery Anterior tibial artery Peroneal artery

In situ vein graft

Reverse vein graft

8 8 2

5 3 2

Table 1 Details of 34 infrainguinal bypass

Composite (arm and leg vein)

PTFE and Miller cuff

2 3

1

PTFE, polytetra¯uoroethylene Table 2 Comparison of the ability of

Duplex prediction Anterior tibial Tibioperoneal Peroneal artery Posterior tibial No vessel artery trunk artery Operative ®ndings Anterior tibial artery Tibioperoneal trunk Peroneal artery Posterior tibial artery No vessel

procedures

colour-coded duplex imaging to predict the best patent vessel for distal anastomosis with the actual operative site of the distal anastomosis

15 0 4 15 3

Table 3 Site of distal anastomosis (upper,

Duplex prediction

Operative ®ndings Upper third Middle third Lower third No vessels

Upper third

Middle third

Lower third

12

1 10 2

8

1

No vessels

3

Dependent Doppler prediction of pedal arch supply Anterior tibial artery Operative ®ndings Anterior tibial artery Peroneal artery Posterior tibial artery No vessel or patent arch

Peroneal artery

Posterior tibial artery

No vessel or no patent arch

middle or lower third of the artery) on the patent vessel at operation compared with colour-coded duplex imaging prediction

j = 0á85 (95 per cent con®dence interval 0á71±1á0) ± very good agreement

Table 4 Dependent Doppler prediction of pedal arch patency and its major vessel supply compared with actual intraoperative arteriography and operative ®ndings

16 1 14

(Table 3). There was also very good agreement between dependent Doppler prediction of pedal arch patency and the major vessel supplying the arch with the intraoperative arteriograms and operative ®ndings (Table 4). However, no arch signal was present in six patients and exploration of all ankle vessels was performed. In three patients, no distal vessels were found at exploration and amputation was required. The other three had a patent distal posterior tibial artery and underwent common femoral artery to posterior tibial artery bypass using in situ long saphenous vein. One of these patients died 2 months after operation with a patent graft. Another developed graft occlusion within 24 h which could not be salvaged and underwent Ó 1999 Blackwell Science Ltd

j = 1á0 ± very good agreement

6

j = 1á0 ± very good agreement

above-knee amputation. The third patient had a primary assisted graft patency at 21 months. The 12-month primary, primary assisted and secondary graft patencies for 34 grafts were 36, 53 and 69 per cent respectively (Fig. 1). Discussion

Over the past 10 years, improvements in the technology of duplex scanners and greater operator experience at imaging leg arteries have greatly enhanced the preoperative assessment of patients with lower limb ischaemia. It has been claimed that colour duplex imaging is superior to arteriography at visualizing cruropedal vessels11. Duplex British Journal of Surgery 1999, 86, 33±37

36

Assessment of leg ischaemia M. J. McCarthy, S. Nydahl, T. Hartshorne et al.

Fig. 1 Cumulative graft patency for 33 vein grafts. One

infrainguinal bypass was performed with polytetra¯uoroethylene and Miller cuff. This graft had a primary patency of 3 months, primary assisted patency of 4 months and then occluded; following this belowknee amputation was performed

imaging also provides a haemodynamic assessment, is non-invasive and is well tolerated by patients. Duplex imaging of the entire lower limb arterial tree may eventually supersede arteriography for the assessment of patients with leg ischaemia11. None of the 37 consecutive patients with critical lower limb ischaemia in this study had preoperative diagnostic arteriography; all were assessed by means of colour-coded duplex imaging and dependent Doppler insonation alone. Very good agreement between colour-coded duplex imaging and the intraoperative arteriographic and operative ®ndings was found, ®rst, in identi®cation of the optimal run-off vessel and, second, in prediction of the site of distal anastomosis. There was also very good agreement in predicting pedal arch patency and the major vessel supplying the arch. The combined preoperative predictions of colour-coded duplex imaging and dependent Doppler insonation obviated the need for preoperative arteriography. This agrees with previous studies that have stated that preoperative diagnostic arteriography is unnecessary for patients before femorodistal bypass grafting8,11. The results question whether intraoperative arteriography is necessary. A future study could omit intraoperative arteriography and compare the results with the postreconstruction completion angiography. Colour-coded duplex imaging and dependent Doppler ultrasonography can be performed in 30 min, including imaging of the arterial tree from the aortic bifurcation to the cruropedal vessels. Clinical decisions about managing patients with peripheral vascular disease can be based entirely on duplex imaging ®ndings alone, although the results obtained are dependent on the level of skill and experience of the vascular technologist. The primary, primary assisted and secondary patency rates of the 33 vein grafts compare well with rates published from this14±16 and other European centres17. British Journal of Surgery 1999, 86, 33±37

While it has been stated that the pedal arch must be patent to achieve long-term patency after femorocrural grafting18±20, Simms et al.21 have argued that femorocrural bypass should still be performed in patients with a patent cruropedal vessel, but no arch. Long-term graft patency can be achieved in this subset of patients but there is an increased risk of amputation. In this study all six patients with no patent arch on Duplex imaging or Doppler ultrasonography were consented ®rst for surgical exploration of the cruropedal vessels but also for primary below-knee amputation if femorocrural bypass was not possible. In this study three patients had no arch signals found before operation but did have suitable distal vessels for grafting. Although the numbers are small, there is still no justi®cation for amputation without exploration. This study supports the ®ndings of others8,9,11 that duplex ultrasonography and Doppler insonation are as good as diagnostic arteriography for imaging and assessing the cruropedal vessels before bypass surgery. A large prospective randomized study is needed to con®rm that preoperative angiography is unnecessary; to date none exists. The results in this study were dependent largely on the skill and experience of the vascular technologist; before abandoning preoperative angiography, any centre should undertake a prospective audit of the results of their noninvasive assessment. References 1 Bell PRF. Femoro-distal grafts ± can the results be improved? Eur J Vasc Surg 1991; 5: 607±9. 2 Koelemay MJW, Legemate DA, van Gurp J, Ponson AE, Reekers JA, Jacobs WHM. Colour duplex scanning and pulsegenerated run-off for assessment of popliteal and cruropedal arteries before peripheral bypass surgery. Br J Surg 1997; 84: 1115±19.


M. J. McCarthy, S. Nydahl, T. Hartshorne et al. Assessment of leg ischaemia 37

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