Comprehensive Summaries of Uppsala Dissertationsfrom the Faculty of Medicine 1060

_____________________________ _____________________________

Infrainguinal PercutaneousTransluminal Angioplasty

in Limbs withSevere Lower Limb Ischaemia

BY

ANNE-MARIE LÖFBERG

ACTA UNIVERSITATIS UPSALIENSISUPPSALA 2001

Dissertation for the Degree of Doctor of Philosophy (Faculty of Medicine) in Radiologypresented at Uppsala University in 2001

ABSTRACT

Löfberg, A.-M. 2001. Infrainguinal percutaneous transluminal angioplasty in limbs withsevere lower limb ischaemia. Acta Universitatis Upsaliensis. Comprehensive Summaries ofUppsala Dissertations from the Faculty of Medicine 1060. 58 pp. Uppsala. ISBN 91-554-5079-2

Infrainguinal bypass grafting is an established method in the treatment of patients withfemoropopliteal and crural occlusive disease leading to critical lower limb ischaemia (CLI).However, complications related to surgical procedure are not negligible and percutaneoustransluminal angioplasty (PTA) has emerged as an alternative. The present thesis coverssome aspects of infrainguinal PTA in patients with chronic severe lower limb ischaemia.

The records of 217 patients undergoing 272 PTA procedures at various infrainguinal arterialsegments were analysed. The indication for intervention was subcritical ischaemia in 76limbs and critical ischaemia in 177 limbs. The role of duplex ultrasound examination in theselection of patients for PTA was retrospectively evaluated following a prospectivevalidation of the method against angiography.

A technically successful PTA was achieved in 89%. The overall 30-day mortality was2.7%. No patient underwent amputation directly related to failed PTA. The primarysuccess rates at 12 and 60 months following femoropopliteal PTA were 40% and 27%compared, to 51% and 36% in limbs undergoing crural artery PTA. Primary success rate inlimbs with SFA occlusion longer than 5 cm was only 12% after 5 years, compared to 32% ifthe occlusion was equal or less than 5 cm in length (p<0.01). In patients undergoing distalPTA through patent infrainguinal grafts, the primary and primary assisted patency rates at3 years were 32% and 53%, respectively. The sensitivity of duplex scanning in the selectionof lesions for PTA was less satisfactory in the popliteal and crural arteries compared to thesuperficial femoral arteries.

In conclusion, the results of infrainguinal PTA performed for treatment of subcritical or CLIseemed to be inferior to the results of surgical interventions reported in the literature.However, due to the fact that the PTA procedure does not preclude the performance ofbypass grafting, it might be an alternative to surgical intervention in limbs with stenotic orshort occlusive lesions.

Key words: infrainguinal, chronic ischaemia, percutaneous transluminal angioplasty,duplex, bypass grafts.

Anne-Marie Löfberg, Department of oncology, radiology and clinical immunology section,Uppsala University Hospital, SE- 751-85 Uppsala, Sweden

© Anne-Marie Löfberg 2001

ISSN 0282-7476ISBN 91-554-5079-2

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Printed in Sweden by Uppsala University, Tryck & Medier, Uppsala 2001

ORIGINAL PAPERSThis thesis is based on the following papers, which are referred to in this textby the Roman numerals given below (I–V).

I. Löfberg A-M, Karacagil S, Ljungman C, Westman B, Boström A,Hellberg A, Östholm G. Percutaneous transluminal angioplasty of thefemoropopliteal arteries in limbs with chronic critical lower limb ischaemia. JVasc Surg 2001; 34:114-121.

II. Löfberg A-M, Lörelius L-E, Karacagil S, Westman B, Almgren B,Bergqvist D. The use of below-knee percutaneous transluminal angioplasty inarterial occlusive disease causing chronic critical limb ischaemia. CardiovascIntervent Radiology 1996; 19:317-322.

III. Löfberg A-M, Karacagil S, Ljungman C, Nyman R, Ulus AT, BoströmA, Östholm G. Distal percutaneous transluminal angioplasty throughinfrainguinal bypass grafts. Submitted.

IV. Karacagil S, Löfberg A-M, Granbo A, Lörelius L-E, Bergqvist D. Valueof duplex scanning in evaluation of crural and foot arteries in limbs withsevere lower limb ischaemia- a prospective comparison with angiography.Eur J Vasc Surg 1996; 12:300-303.

V. Löfberg A-M, Karacagil S, Hellberg A, Boström A, Ljungman C,Östholm G. The role of duplex scanning in the selection of patients withcritical lower limb ischaemia for infrainguinal percutaneous transluminalangioplasty. In press (Cardiovasc Intervent Radiology).

Reprints have been made with the permission of the publishers

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CONTENTSABBREVIATIONS 6INTRODUCTION 7AIMS OF THE THESIS 9MATERIAL AND METHODS 10Data collection 10Inclusion and exclusion criteria 10Patient characteristics 12Definitions of lower limb ischaemia 13Guidelines for selection of treatment modalities 13Duplex scanning 14PTA Technique 15Level of PTA 16Follow-up 19Analysis of data 20Statistic analysis 20RESULTS 21Technical success 21Early complications (within 30 days) 22Results of femoropopliteal PTA 23Results of crural artery PTA 27Results of infrapopliteal PTA through infrainguinal grafts 28Accuracy of infrapopliteal arterial duplex scanning 30Selection of patients for infrainguinal PTA 31DISCUSSION 33Femoropopliteal PTA 33Crural artery PTA 35Infrapopliteal PTA through infrainguinal grafts 37Accuracy of infrapopliteal duplex scanning 38Selection of patients for infrainguinal PTA 39CONCLUSIONS 41ACKNOWLEDGEMENTS 42REFERENCES 44

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ABBREVIATIONSABPI Ankle brachial pressure indexCAD Coronary artery diseaseCLI Critical limb ischaemiaCTA Computed tomography angiographyCVD Cerebrovascular diseaseDA Distal anastomosesHT HypertensionMRA Magnetic resonance angiographyNA None availableNPV Negative predictive valueNS Not significantPPV Positive predictive valuePSV Peak systolic velocityPTA Percutaneous transluminal angioplastyPTFE PolytetrafluoroethyleneSFA Superficial femoral arterysub-CLI Subcritical limb ischaemiaSVS Society for Vascular SurgeryISCVS International Society for Cardiovascular SurgeryTASC Trans Atlantic Inter-society ConsensusTP Tibioperoneal

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INTRODUCTIONThe incidence of atherosclerotic disease affecting the lower leg arteries,determined by objective testing, ranges from 2.2% of a population aged 38 to82 years to 17% of a population aged 55 to 74 years (Crigui 85, Fowkes 91).Chronic occlusive arterial disease in the femoropopliteal segment is three tofive times more frequent than iliac disease. Occlusive lesions are morecommon than stenosis in the femoropopliteal arteries (Martin 92).

Most of the patients with lower limb occlusive disease are asymptomatic.Clinical symptoms range from mild claudication to critical lower limbischaemia (CLI). In most instances, an accurate history, physical examinationand ankle pressure measurements by a hand-held Doppler instrument establishthe diagnosis in patients with lower limb ischaemia. In limbs where there isclinical indication for surgical or endovascular intervention duplex scanningis the most common first choice of objective diagnostic modality. Duplexscanning which combines B-mode ultrasound imaging with pulsed-Dopplerfrequency spectral analysis allows direct visualisation of the arteries, togetherwith measurement of the arterial flow velocities. The recent development ofcolour-flow imaging has facilitated the identification of the vascular anatomyand the localisation of the lesions. Measurement of the specific components ofthe flow-velocity waveforms by spectral Doppler analysis, such as peaksystolic velocity (PSV), indicates the severity of atherosclerotic lesions(Legemate 91, Karacagil 94, 96).

Duplex scanning has been widely used for the selection of treatment modalityin patients with lower limb arterial insufficiency (Jager 85, Edwards 91,Elsman 96, Levi 98, van der Zaag 98, Sarkar 98, Schneider 99, Ascher 99).It is also commonly used for surveillance after surgical or endovascularintervention (Moody 89, Lundell 95, Bergamini 95, Dougherty 98, Quinn98). Magnetic resonance angiography (MRA), as another non-invasivemodality, has been proved to have an even greater sensitivity thanconventional angiography for detecting distal runoff vessels. It is not asoperator dependent as duplex scanning and is less time consuming. (Levy 98,Cambria 97, Carpenter 92, Owen 92). Computed tomography angiography(CTA) for depicting infrainguinal vessels is still controversial and the amountof contrast agent needed still high (Kramer 98, Lawrence 95, Hayashi 99,Sugahara 98). During recent years more and more patients have been selectedfor endovascular or surgical interventions from the findings obtained solely

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from duplex scanning or MRA (Carpenter 94, Elsman 95, 96, Schmiedl 96,Huber 97).

Despite recent advances in noninvasive methods for imaging the lower legarteries, such as duplex scanning and MRA with or without contrast agents,conventional contrast angiography remains the ‘gold standard’ by which allother investigations are judged. In cases where noninvasive diagnosis revealsnondiagnostic findings or if the clinical findings are not in accordance withthe noninvasive results, there is still a definite need for diagnosticangiography in planning interventions.

The documentation of lower limb arterial insufficiency is not an absoluteindication for intervention. Only 5–7% of patients with claudication willcome to amputation (Boyd 62, Imparato 75, Dormandy 91). After carefuljudgement of the symptoms and risk factor analysis, an individual treatmentplan is decided in limbs with claudication, either conservative or invasive,endovascular or surgical. The incidence of CLI among all patients withsymptomatic ischaemia of the leg is 1–3% (Dormandy 88, Varty 96).However, CLI constitutes a definite indication for arterial intervention (Bolin88, Lepänto 96).

The prognosis of patients with CLI in terms of life expectancy is notoriouslypoor. Patients with CLI have a 50% survival rate after 5 years regardless oftreatment (ICAI 97, Wolfe 97). Improved peripheral circulation cannotprolong survival but may save the legs. The decision between endovascularand surgical intervention is usually guided by anatomical factors such as thelocalisation, the extent of atherosclerosis and the status of the runoff vessels.During recent years, as the complications related to endovascular procedureshave diminished with the introduction of modern catheters and balloons, theindications for angioplasty have increased (Johnston 92, Stanley 96)). Insome patients with CLI and associated severe risk factors, conventionalsurgical procedures might be contraindicated and endovascular interventionmight be the only alternative to prevent amputation. Less durable proceduresmight be acceptable in these patients with limited life expectancy (Muluk 01,Källero 85, Sec Eur Cons 92).

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AIMS OF THE THESISThe present thesis was designed to analyse the outcome following PTA inlimbs with severe lower limb ischaemia and to study the role of duplexscanning in the selection of limbs for infrainguinal PTA. The first part of thethesis (studies I, II and III) covers the results of infrainguinal PTA. Theoutcome of infrainguinal PTA is dependent on symptoms, the extent and thelocalisation of atherosclerotic lesions. It is reasonable to speculate that theresults might be easier to interpret if the outcomes of endovascular proceduresare analysed in homogenous groups with less debatable indications, especiallywhen the number of procedures is limited. This was the reason for theevaluation of only infrainguinal endovascular procedures in limbs withsubcritical or CLI. In order to achieve more specific outcome analysis, thetype or localisation of PTA was further divided into three groups:femoropopliteal, crural and infrapopliteal through patent infrainguinal bypassgrafts.

In the second part of the thesis (studies IV and V), the accuracy of duplexscanning was validated against conventional angiography. Following thisvalidation study, the role of duplex scanning in selection of patients for PTAwas evaluated.

In summary, the specific aims were as follows:

1 – to evaluate the results of PTA of femoropopliteal arteries in patientswith subcritical or CLI.

2 – to determine the efficacy, safety and long-term results of crural arteryPTA in limbs with CLI.

3 – to evaluate the results of PTA performed through infrainguinal bypassgrafts for stenotic or occlusive lesions at the distal anastomosis and/or inthe runoff arteries.

4 – to study the accuracy of duplex scanning in the evaluation of theinfrapopliteal arteries.

5 – to investigate the role of duplex scanning in the selection of patients withsubcritical or CLI for infrainguinal PTA.

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MATERIALAND METHODS

Data collectionWritten reports of all lower limb angiographies performed during the studyperiods and the medical files of these patients were retrospectively analysed inorder to select those who were included in studies I, II and III. Following thisselection, the angiographies of those who were included in the thesis were re-evaluated. Relevant data from medical and duplex scan files, together withinformation from the Swedish Population Registry were gathered forevaluation of outcome.

During the study period, 18,000 arterial duplex scans were performed in ourvascular laboratory. Retrospective analysis of all these scans gave theopportunity of evaluating the noninvasive selection of patients for PTA. Italso contributed to objective analysis of the results of PTA as all patientsincluded in study III and 78% of those included in study I were followed byduplex scanning.

Inclusion and exclusion criteriaThe study periods, design and localisation of PTA are summarised in Table I.

Table I. Study designs

Study Study period Study design Inclusion/PTA localisation

I 1992-1999 Retrospective Limbs with subCLI/CLIPTA of femoropopliteal arteries

II 1989-1993 Retrospective Limbs with CLIPTA of crural arteries

III 1992-2000 Retrospective Limbs with infrainguinal bypass.PTA of distal anastomosis and/or

runoff arteriesIV 1995 Prospective Severe lower limb ischaemia

Duplex prior to angiography

V 1995-1999 Retrospective Limbs with subCLI/CLIInfrainguinal PTA

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In study I, as the results of infrapopliteal PTA in limbs with severe lowerlimb ischaemia have been previously reported (study II), patients undergoingcrural artery PTA alone or simultaneously with femoropopliteal dilatationwere excluded, as were those infrainguinal endovascular proceduresperformed for claudication.

In study II, all patients undergoing crural artery PTA during the study periodwere included. Patients with infrainguinal bypass grafts undergoing cruralartery PTA were excluded.

In study III, infrainguinal grafts with stenosis at the proximal anastomoses orin the graft without associated distal lesions undergoing PTA were excluded,as were those receiving intraarterial thrombolytic therapy for graft occlusionwithout additional PTA. Grafts with combined proximal and distal lesions aswell as patients receiving thrombolysis followed by PTA at the distalanastomosis or in the runoff vessels were included. The reason for the above-mentioned criteria being used for inclusion in study III was to evaluate theresults of PTA selectively at the distal anastomotic site and/or in the runoffarteries.

In study IV, all patients with severe lower limb ischaemia who underwentduplex scanning prior to angiography were included.

In study V, patients having sub-CLI or CLI who underwent duplex scanningwithin 3 months prior to conventional diagnostic angiography and orinfrainguinal PTA were included. Patients with significant iliac artery lesionsand those with previous infrainguinal surgical reconstructions undergoingangiography or PTA of graft or distal lesions were excluded, as were thoseundergoing thrombolysis due to acute or subacute infrainguinal arterialocclusions. Patients with lower limb arterial insufficiency who underwentlower extremity conventional or MRA prior to duplex scanning were alsoexcluded, as the findings of these investigations might have affected theinterpretation of duplex scanning at the time of examination.

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Patient characteristicsPatient demographics are summarised in Tables II and III.

Table II. The total number of patients, limbs, age and sex distribution

Study No. ofpatients

No. oflimbs

Age(years)Median

Sexmale/female

I 94 121 75 52/42

II 82 86 72 42/40

III 41 57 70 22/19

IV 38 40 71 17/21

V 150 162 79 72/78

Table III. Patient characteristics (limbs)Study Claudi

-cationSub-CLI

CLI Diabetes HT CAD CVD Smoking

I 0 30 91 52 (43%) 41 (34%) 38 (32%) 13 (11%) 32 (35%)

II 0 30 56 61 (74%) 30 (36%) 51 (62%) 6 (7%) 16 (20%)

III * 0 16 30 21 (46%) 24 (51%) 21 (46%) NA 28 (61%)

IV** 6 12 20 17 (45%) 14 (37%) 20 (53%) NA 10 (26%)

V*** 0 NA NA NA NA NA NA NA

*Indication at the time of by-pass grafting

**Number of patients

***Indication at the time of duplex-scanning

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Definitions of lower limb ischaemiaCLI was defined according to SVS/ICSVS by either of the following twocriteria: recurring ischemic rest pain that persists for more than 2 weeks andrequires regular analgesics, with an ankle pressure of 40 mm Hg or less;ulceration or gangrene of the foot or toes, with ankle pressure 60 mm Hg orless (Rutherford 97). Limbs with rest pain or ulcer, having either falselyelevated ankle pressures or having an ankle brachial pressure index (ABPI)less than 0.5 and ankle pressure over 40 mm Hg were defined as havingsubcritical ischaemia (TASC 00).

Guidelines for selection of treatment modalitiesFollowing clinical investigation and simple ankle pressure measurements,potential candidates for intervention underwent duplex scanning. In ourdepartment, PTA was generally the initial treatment of choice for occlusivelesions less than 10 cm in length in the femoropopliteal segment and less than5 cm in length in crural arteries in limbs with subcritical or CLI. In 13patients in study I, the length of occlusion in the SFA was equal or more than10 cm in length. In patients with femoropopliteal and/or cruropedalatherosclerotic occlusive lesions, which are not amenable to PTA,reconstructive surgery is the treatment of choice if the symptoms justifyintervention. When duplex scanning provided satisfactory visualisation andspectral Doppler evaluation in the inflow and outflow arteries, and if thelesions were not suitable for PTA according to the guidelines mentionedabove, surgery without preoperative angiography was performed. The reasonfor performing angiography in some patients with diagnostic duplex scansprior to surgical intervention was mainly due to policy differences amongvascular surgeons. No patients with claudication underwent crural artery PTAor femorodistal bypass grafting during the study period.

There were no strict guidelines for the selection of treatment modality inlimbs with infrainguinal graft lesions. However, PTA was the treatment ofchoice for localised stenotic lesions (less than 2 cm in length) in the graftand/or at the distal anastomosis detected after the initial 3-month periodfollowing surgery. PTA was also the choice of initial treatment for stenosis orocclusions less than 5cm in length in the runoff arteries. In cases where PTAwas considered unsuitable due to extensive crural artery changes, femorodistaljump bypass grafting was the choice of treatment if technically feasible (i.e,if there was a patent distal vessel present).

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In study III, the patients were selected for endovascular intervention using thefindings obtained from duplex scanning. Peak systolic velocity (PSV) ratiomore than 3 was the indication for intervention in grafts with stenosis(Olojuba 98, Bandyk 84, Levy 98). The following duplex criteria were usedfor definition of grafts at risk of occlusion in limbs with runoff lesions: PSVin the graft less than 45 cm/sec irrespective of symptoms and/or a decrease inABPI measurements greater than 0.15 combined with rest pain or an ulcer(Dougherty 98, Taylor 92, Wilson 96, Moody 90).

Duplex scanningDuplex scanning was performed using an Acuson model 128 XP or Seqouiafitted with 4-6 MHz linear, 2-4 MHz convex or vector array probes (Acuson,Mountainview, CA, USA). Duplex studies were performed with the patient ina supine position, starting from the infrarenal aorta. The popliteal andtibioperoneal segments were studied with the knee slightly flexed. Duplexscanning of the crural and foot arteries was not routinely performed,especially in those with a patent popliteal artery. Each arterial segment wasexamined over its entire length, searching for colour changes, whichsuggested the presence of an arterial lesion. PSV from these areas wascompared with the normal segments immediately proximal to and rarelydistal from the lesions. A PSV ratio (PSV-stenosis/PSV-normal segment) ofequal to or more than 2,5 was considered as indicative of a 50% or greaterstenosis when the Doppler angle was less than 60˚ (Fig.1) (Moneta 92). If thearterial segment was clearly visualised with B-mode images but giving nodetectable Doppler signal, it was considered to be occluded. Theinvestigations were interpreted as non-diagnostic if the artery in questioncould not be adequately visualised by B-mode images or if pulsed Dopplersamples could not be obtained with an angle of insonation less than 60˚.

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Fig. 1 a-colour flow imaging of SFA and deep femoral artery; b-SFA stenosis with PSV 6m/sec; c-high resistance flow in the femorpopliteal vein graft due to distal poplitealocclusion; d-distal anastomosis of a femorodistal bypass with colour changes indicatingstenosis.

During the initial phase of the study, similar criteria were used for diagnosisof more than 50% stenosis in the infrainguinal graft or at the anastomoticsites as in the native arteries. During the last, two-year period, a PSV ratio ofequal to or more than 3 was used to define significant graft lesions thatrequired intervention (Olojugba 98, Bandyk 89, Grigg 88, Mattos 93, Sladen89, Belkin 94, 97).

PTA TechniqueAntegrade puncture of the femoral artery was used in limbs when pre-PTAduplex scanning demonstrated patent aortoiliac segments. In patients withextreme obesity, or where duplex scanning was unavailable or inconclusivethe crossover technique from the contra-lateral side was used for angiography

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and PTA. The crossover technique has been used more often during recentyears even in cases with diagnostic iliac duplex scanning, in order to avoidcompression of the ipsilateral femoral artery following PTA. Catheterisationwas made through a 2.00-2.50 mm (6-8 French) introducer and with ‘roadmapping’ of the arteries. Low profile balloons with a shaft size of 1.65-2.30mm (5-7 French) (Schneider-Europe AG, Zurich, Switzerland) and a balloondiameter ranging from 2.5 to 6 mm were used. For recanalisation of totalocclusions a low friction 0.89 mm (0.035 inch) diameter guide wire was used(Terumo Co, Japan). Immediate post-angioplasty angiograms were obtainedfor all patients. Technical success was defined as PTA resulting in less than50% residual stenosis after dilatation. Intra-arterial heparin (5000 units) wasinjected during the procedure. The patients received low molecular heparin(Enoxaparin 40 mg sc) 4–6 hrs after the procedure and were on lifetimeantiplatelet treatment (acetylsalicylic acid/ 160 mg daily).

Level of PTAThe level of PTA in each study is summarised in Table IV.

Table IV. The level of PTA

Level of PTA Study I Study II Study III Study V

Only SFA 68 0 0 22

Only popliteal 13 0 0 5

Only crural 0 39 0 5

Combined SFA -popliteal 40 0 0 22

CombinedSFA/popliteal/crural

0 55 0 20

Distal anastomosis (DA) 0 0 13 0

Runoff arteries 0 0 32 0

Combined DA-runoffarteries

0 0 12 0

Figures 2 through 5 demonstrate Pre- and post- PTA angiograms in somepatients undergoing infrainguinal PTA at various arterial segments.

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Fig. 3 Occlusion of AFS and tibioperoneal arteries (2 and 4 cm resp.) in 80-year-old womanwith gangrene of the right foot. A-B before PTA. C-D after PTA. The ulcers healed afterPTA but the patient died one year later of heart failure.

Fig. 26 cm long occlusion ofSFA in a 60-year-oldman. A- before PTA B-after PTA. The leg wasamputated in less than ayear despite re-PTA andattempts with bypassoperations.

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Fig. 4Short stenosis in AFS and 7cm occlusion of the peronealartery in a 65-year-old manwith CLI. A-B and C beforePTA, D-E and F after PTAAfter PTA the ulcers healedand duplex scanning at 36months, showed no signs ofreocclusion.

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Follow-upFollowing infrainguinal PTA performed for treatment of sub-CLI or CLI,limbs undergo routine clinical examination and ABPI measurements at thefollowing intervals in our department: before discharge, at 1, 6 and 12months, and then on a yearly basis. During the last five years (1996–2001),the majority of patients were followed by duplex scanning at these intervals.

The following criteria were used for definition of clinical improvement: totalor partial disappearance of rest pain (intermittent rest pain that did not requireregular analgesics), healing of ulcers. In patients undergoing duplex scanning,special attention was paid to assessing the patency of the dilated segment. Inlimbs with clinical improvement following recanalisation of occludedsegments, demonstration of an open dilated segment with less than 50%stenosis was considered as patent. PTA results were considered as successfulin limbs with clinical and haemodynamic improvement. Recurrence ofsymptoms and/or haemodynamic deterioration and/or restenosis/occlusionverified by duplex scanning, were defined as failure.

Fig. 573-year old woman underwent bypassgrafting to the posterior tibial artery due togangrene. Duplex scanning at 36 monthsrevealed occlusion of the posterior tibialartery below the distal anastomosis. A-angiography before PTA, B- after PTA. Thevasospasm was successfully solved withnitroglycerine. Repeated duplex scanningduring 4 years showed patent graft andrunoff vessel.

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Analysis of dataThe technical details of PTA and follow-up data were not subjected to blindanalysis but the angiographic data were registered before analysis of theoutcome. The time difference between data collection from angiographies andpatient files was at least 6 months. The findings obtained from duplexscanning and angiography, were subjected to blind analysis by two differentinvestigators. The comparison between duplex scan findings and angiographywas analysed by the third investigator.

Statistical analysisLife tables for patency rates were constructed by the actuarial methodaccording to SVS/ICSVS reporting standards and the differences betweengroups were analysed using the Log-rank test (Rutherford 97).

Accuracy, sensitivity, specificity, positive predictive and negative predictivevalues for duplex scanning in the selection of limbs for PTA were calculatedfrom two-way contingency tables. The arterial segments with non-diagnosticduplex scan findings were interpreted as not suitable for PTA.

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RESULTS

Technical successIn study I, the technical success rate was 88% (106/121) in limbs undergoingfemoropopliteal PTA. Among 15 technical failures in 14 patients, 11 were atthe superficial femoral level. All but two had occlusive lesions and the lengthof occlusion was longer than 5 cm in 10 cases. Two patients underwent acuteinfrainguinal bypass grafting following perforation and thrombosis of theSFA in one and thrombosis of the popliteal artery following successful PTAof the SFA in the other. In all other patients, technical failures did not worsenthe status of the runoff vessels distal to the lesions. Six patients underwentelective infrainguinal bypass grafting following technical failure. In two caseselective major amputation was undertaken due to poor distal runoff. Onepatient died after six weeks and the remaining four managed withconservative treatment following failed PTA. There was no limb loss as adirect complication of the PTA procedure, such as distal embolisation orthrombosis of crural arteries precluding the performance of bypass grafting.

In study II, a technically successful PTA in at least one crural artery wasachieved in 88% procedures (83/94 procedures). There was technical failurein a total of 27 segments, 26 of which were at the crural level. Among 11procedures where no crural artery could be recanalised, one patient underwentacute distal reconstruction, three were amputated, three received electivebypass grafting, two died within 6 months and two were lost to follow-upduring the first 3 months after PTA. In six instances among the initial 40procedures, where PTA of the superficial femoral artery and/or poplitealartery preceded PTA of the crural artery, a peripheral embolisation wasobserved and in five cases it was possible to perform a successfultranscatheter embolectomy. In one case with peripheral embolisation,successful lysis was achieved with local streptokinase infusion. Since wereversed the order of procedures, performing PTA of the crural arteriesbefore that of the femoral artery, no embolisation has been noted.

In study III, a technically successful PTA was achieved in 91% (52/57) ofdistal PTA procedures performed through patent infrainguinal grafts. In twocases with acute femorodistal graft occlusion (both PTFE grafts with a distalvein cuff) following successful thrombolysis, the stenosis at the distalanastomosis could not be recanalised. Both patients underwent surgical

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revision with vein patch angioplasty. One of these patients died 4 monthsafter surgery with a patent graft and the other underwent amputation aftergraft occlusion at 3 months. In one patient with femoropopliteal vein graftand poor distal runoff, PTA of multiple short stenosis in the proximalanterior tibial and peroneal arteries failed. This patient underwent amputationwith patent graft after one month. In the fourth patient with femoropoplitealvein bypass and poor distal runoff, the graft occluded following an attempt atPTA at the distal anastomosis. Following urgent graft thrombectomy andpatch angioplasty, the graft occluded after 2 months and the patientunderwent amputation after 28 months. In the fifth patient withfemoropopliteal vein bypass, there was a residual stenosis greater than 50%after PTA at the distal anastomotic site. The graft was patent at 26 monthswith duplex verified distal stenosis and the patient had moderate claudication.

Early complications (within 30 days)In study I, four patients died within 30 days of PTA (4.3%). One patient dieddue to myocardial infarction on the same day after uncomplicated successfulsuperficial femoral artery PTA. The other deaths were due to renal andcardiac insufficiency in one patient and myocardial infarction in three,occurring 1–2 weeks after PTA. Fifteen patients developed groin haematomas(12%), of whom only one received a blood transfusion and no patientsunderwent acute surgical intervention. Two patients had temporary creatinineelevation. No patient had an irreversible change in his or her creatinine.

In study II, of 82 patients undergoing 94 crural artery PTA, two patients dieddue to myocardial infarction (post-PTA mortality 2.4%). There was no limbloss as a complication of the PTA procedure. Fourteen patients developedgroin haematomas (15%). Five received a blood transfusion and twounderwent acute surgical intervention. One patient developed non fatalmyocardial infarction during the first week after PTA. One patient hadtemporary creatinine elevation.

In study III, there was no mortality during the initial 30-day period followingPTA procedures through infrainguinal grafts. In five cases, mild haematomawas observed at the puncture site that did not require surgical intervention orblood transfusion. In one patient the PTA attempt at distal anastomosisresulted in graft occlusion and this patient underwent urgent graftthrombectomy and patch angioplasty, as mentioned earlier.

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Results of femoropopliteal PTACumulative primary success rates at 6, 12, 36 and 60 months were 59%,50%, 27% and 27%, respectively (Table V).

Table V. Cumulative life-table analysis for primary success rate (121 procedures)

No. of patients withdrawn due to the short time since PTA, loss to follow-up, or death

The cumulative primary assisted success rate at 60 months was 34% (Fig. 6).

Fig. 6 Cumulative life-table analysis for primary assisted succes rate

--------------------------------------------------------------------------------------------Interval No. of limbs No. failed No. Interval Cumulative(months) at risk PTA withdrawn* success success% SE%--------------------------------------------------------------------------------------------

0-6 121 47 15 0.59 100 06-12 59 8 5 0.86 59 8.7

12-18 46 9 8 0.78 50 2.518-24 29 3 0 0.89 40 424-30 26 3 5 0.87 35 1.830-36 18 2 1 0.8 83 2.236-42 15 0 7 1 27 242-48 8 0 1 1 27 048-54 7 0 1 1 27 054-60 6 0 0 1 27 0

Time (months)

60544842363024181260

1.0

.9

.8

.7

.6

.5

.4

.3

.2

.1

0.0

At risk 121 61 53 34 30 21 18 11 9 7 7

34 %

Cum

ulat

ive

prim

ary

assis

ted

succ

ess x

100

%

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The primary assisted success rate in limbs with single SFA stenosis was 53%at 60 months, compared to 42% in limbs with multiple stenosis (p=NS) and18% in those with occlusions (Table VI and Fig. 7).

The primary success rate in limbs with an SFA occlusion longer than 5 cmwas only 12% after 5 years compared to 32% if the occlusion was 5 cm orless in length (p<0.01) (Table VII). Among 13 cases with SFA occlusions 10cm or more in length, there were seven technical failures and five re-occlusions within 5 months.

The symptoms (subcritical, CLI), presence of diabetes, preoperative ABPI(ankle brachial pressure index) less than 0.2, combined femoral and poplitealPTA, the number of occluded crural arteries (one compared with two orthree) and the occlusion of the foot arteries (dorsal pedal and plantar arteries)did not adversely affect the outcome. The occlusion of all three crural arterieswas observed in 33%. Most limbs had only one patent crural vessel (49%).Dorsal pedal and/or plantar arteries were partially or totally occluded in 78%.

Twelve patients underwent amputation after failed PTA without any attemptat distal bypass grafting because of severe distal atherosclerotic involvement.Fifteen patients underwent infrainguinal bypass grafting (17 procedures) afterfailure of PTA. In these patients with restenosis or occlusion at the site ofPTA, we did not observe worsening of the atherosclerotic process in therunoff arteries on preoperative or on-table postreconstruction angiograms.The cumulative limb salvage rate following endovascular and vascularinterventions was 86% at 5 years (Fig. 8). The cumulative survival rate was51% at 5 years (Fig. 9).

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Table VI. Cumulative life table success rates in various groups

Fig. 7 Cumulative life-table analysis for primary assisted success rate in patientswith SFA single stenosis (1); SFA multiple stenosis (2) and SFA occlusions (3)

At risk 32 24 21 14 11 8 7 3 3 2 2 (1)31 16 14 6 6 5 5 4 3 3 3 (2)45 14 12 10 10 6 5 3 2 2 2 (3)

Time (months)

60544842363024181260

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-------------------------------------------------------------------------------------------------Various Groups 12 months 36 months 60 months

% (at risk) % (at risk) % (at risk)-------------------------------------------------------------------------------------------------1-Primary (all) 40 (46) 27 (15) 27 (6)2-Primary assisted (all) 48 (53) 34 (18) 34 (7)3-Secondary (all) 49 (54) 32 (19) 32 (7)4-Primary (stenotic lesions) 50 (31) 39 (10) 39 (3)5-Primary (occlusive lesions) 27 (15) 16 (5) 16 (3)6-Primary (SFA- single stenosis) 72 (19) 49 (7)* 49 (2)*7-Primary (SFA -multiple stenosis) 34 (12) 34 (5) 34 (3)8-Primary (SFA -occlusions) 23 (9) 11 (3) 11 (1)9-Primary (SFA -occlusions <5 cm) 47 (35) 32 (12) 32 (3)10-Primary (SFA -occlusions >5 cm) 17 (3) 12 (2) 12 (2)11-Primary assisted (SFA -single stenosis) 75 (21) 53 (7)* 53 (2)*12-Primary assisted (SFA -multiple stenosis) 42 (14)* 42 (5)* 42 (3)*13-Primary assisted (SFA-occlusions) 31 (12) 18 (5) 18 (2)

SFA = superficial femoral artery*SE > 10Comparisons: 4-5: p<0.01; 6-7:p=NS; 6-8:p<0.001;7-8=p=0.01; 9-10:p=0.001; 11-12:p=NS;11-13:p<0.001; 12-13:p<0.01

26

At risk 100 79 71 63 63 56 52 39 32 28 25

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%

Fig. 8 Cumulative life-table analysis for limb salvage rate

Fig. 9 Cumulative life-table analysis for survival rate

At risk 94 80 74 68 68 63 58 46 41 36 30

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Results of crural artery PTACumulative primary clinical success rates at 6, 12, 24 and 36 months were55%, 51%, 36%, and 36%, respectively (Table VII). Cumulative secondarysuccess and limb salvage rates at 36 months were 44% and 72%, respectively(Tables VIII and IX).

Table VII. Cumulative life-table analysis for primary success rate

Table VIII. Cumulative life-table analysis for secondary success rate

Table IX. Cumulative life-table analysis for limb salvage rate

----------------------------------------------------------------------------------------------------Interval No. of limbs No. failed No. with drawn* Interval Cumulative SE%(months) at risk PTA success success%----------------------------------------------------------------------------------------------------0-6 86 35 14 0.55 100 06-12 37 2 9 0.93 55 612-14 26 6 11 0.70 51 724-36 9 0 2 1 36 9.7

----------------------------------------------------------------------------------------------------Interval No. of limbs No. failed No. with drawn* Interval Cumulative SE%(months) at risk PTA success success%----------------------------------------------------------------------------------------------------0-6 86 32 14 0.59 100 06-12 40 3 9 0.91 59 5.912-14 28 4 12 0.81 54 6.924-36 12 0 3 1 44 9.5

----------------------------------------------------------------------------------------------------Interval No. of limbs No. failed No. withdrawn* Interval Cumulative SE%(months) at risk PTA success success%----------------------------------------------------------------------------------------------------0-6 86 16 18 0.79 100 06-12 52 2 18 0.95 79 512-14 32 1 11 0.96 75 6.624-36 20 0 7 1 72 8.5

* No. of patients withdrawn due to the short time since PTA, loss to follow-up, or death

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In ten limbs, secondary crural artery PTA was performed, which resulted in aslightly improved patency rate at 36 months (44% compared to 36%). Thepresence of diabetes, a preoperative ABPI less than 0.2, combinedfemorocrural PTA, the type of lesion (occlusion compared with stenosis) andthe number of patent crural arteries after successful PTA (one compared withtwo or three) did not adversely affect the results. One patient required acutefemorodistal reconstruction. Thirteen patients underwent electiveinfrainguinal bypass surgery due to reocclusion at a mean (SE) of 7.2 (3.9)months after PTA. Twenty patients underwent amputation at a mean (SE) of4.7 (1.7) months (range 1–37 months) after reocclusion of PTA without anyattempt at distal reconstruction because of severe distal atheroscleroticinvolvement. Among 49 patients who did not require surgical reconstructionor primary amputation after PTA, 15 died during the follow-up period (mean10.8 months).

Results of infrapopliteal PTA through infrainguinal graftsThe median (range) ABPI measurements increased from 0.42(0.2-0.8) to0.53(0.3-1.0) after technically successful PTA. The overall primary patencyrate following PTA was 32% at the end of 3 years (Table X).

Table X. Cumulative life-table analysis for primary patency rate (57 procedures)

The majority of events, either re-intervention in patent grafts or graftocclusions, occurred during the initial 6-month period after PTA (23 out of37 events). In eight patients, following graft occlusion after a mean (SD)(range) interval of 12.5 (13.5) (1–35) months, no further intervention oramputation was performed. Five of these patients had claudication and threehad subcritical ischaemia at the time of their last visit (a median of 11 months

---------------------------------------------------------------------------------------------------Interval No.of limbs No.failed No.withdrawn* Interval Cumulative SE%(months) at risk PTA success success%---------------------------------------------------------------------------------------------------0-6 57 23 1 0.59 100 06-12 33 10 1 0.69 59 612-18 22 2 3 0.90 41 318-24 17 1 2 0.93 37 0.624-30 14 1 3 0.92 35 0.430-36 10 0 1 1 32 0.5

* No. of patients withdrawn due to the short time since PTA, loss to follow-up, or death

29

after occlusion). Sixteen additional endovascular interventions were requiredin ten patients. Twelve of these procedures were performed due to duplex-verified restenosis or occlusion at the site of previous PTA in patent grafts.These additional procedures resulted in a primary assisted patency of 53% at3 years (Fig.10).

Fig.10 Cumulative primary and primary assisted life table patency. SE less than 10at the end of 3 years and the numbers at risk are given.

Femorocrural or jump bypass grafting was performed following graftocclusion in one case and duplex-verified stenosis or occlusion at the site ofPTA with patent graft in three cases. There were no significant differences inpatency rates with respect to the graft material, the site of distal anastomosis,the status of distal runoff, the presence of diabetes mellitus, the type of lesion(stenosis or occlusion), combined PTA at the proximal anastomosis or graft,and the use of thrombolysis before dilatation. The limb salvage rate at 36months was 83%.

Time (months)

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There were six major amputations during the follow-up period. Two patientsunderwent amputation without reintervention at 1 and 7 months followingPTA and graft occlusion due to poor distal runoff and CLI. Another patientwith CLI was amputated with a patent but haemodynamically failed graft. Inthree patients major amputations were performed following re-intervention(two thrombolysis and distal PTA and one jump graft). The median (range)interval from the time of initial PTA and amputation was 5 (1–23) months.

Accuracy of infrapopliteal arterial duplex scanningThe overall correlation between selective femoral angiography and duplexscanning for crural and foot arteries is presented in Table XI.

Table XI. Duplex scanning vs. angiography

The duplex scanning of the tibioperoneal trunk, crural and pedal arteries hadan accuracy of 80% with a Kappa value of 0.6. The sensitivity, specificity,positive predictive and negative predictive values were 83%, 77%, 79% and81%, respectively. The specificity was relatively low for the peroneal artery(58%) compared to the anterior tibial (86%), posterior tibial (76%) and footarteries (81%). The overall accuracy of duplex scanning for detection ofsignificant stenosis or occlusion of the crural and foot arteries was 83%;Kappa values for various segments varied between 0.53 and 0.71, with the

----------------------------------------------------------------------------------------------------Segment n Accuracy Sensitivity Specificity PPV NPV Kappa

(%) (%) (%) (%) (%) (%)----------------------------------------------------------------------------------------------------Poplitea/below knee 40 88 79 92 85 83 0.76TP trunk/crural/pedal 240 80 83 77 79 8 0.60TP trunk/crural 180 80 83 76 78 80 0.59TP trunk 40 80 71 87 80 80 0.62Tibialis anterior 40 80 73 86 80 80 0.64Tibialis posterior 40 80 84 76 84 74 0.61Peroneal 40 76 93 58 71 89 0.57Dorsalis pedis 40 88 85 89 79 92 0.71Plantar arch 40 78 78 76 82 72 0.53Pedal arteries 80 83 81 84 81 84 0.64TP/crural/pedal* 200 83 86 80 82 84 0.66

*(50% or occlusion)The values were calculated according to the contingency table. For the TP/crural/pedal (50% orocclusion)% stenosis was graded into two groups: normal or ≤ 50%; > 50% or occlusion.

31

highest value for the dorsal pedal artery and the lowest for the peroneal arteryand the plantar arch.

Selection of patients for infrainguinal PTAThe number of arterial segments that were not examined or were non-diagnostic at the time of duplex scanning in the whole series is shown inTable XII. In three cases undergoing infrainguinal PTA where iliac duplexscanning was considered non-diagnostic, the spectral Doppler analysis ofexternal iliac and common femoral arteries was normal in all. All these casesunderwent angiography with cross-over technique and the patency of the iliacarteries was verified before infrainguinal PTA. The number of non-diagnosticor non-available scans at the crural level was higher than in the othersegments.

Table XII. The number of arterial segments on the symptomatic side that were not

examined or non-diagnostic at the time of duplex scanning in 162 limbs undergoing

diagnostic angiography or infrainguinal PTA

Forty-two procedures (57%) were performed at multiple arterial segments.Prediction of performing an infrainguinal PTA by duplex scanning and theoutcome measures in patients who did not undergo PTA are summarised inTable XIII.

-----------------------------------------------------------------------------------------------Duplex scanning

Segment Not examined Non-diagnostic-----------------------------------------------------------------------------------------------Iliac arteries (n=162) 10 (6%) 18 (11%)SFA (n=162) 0 14 (9%)Popliteal artery (n=162) 0 17 (10%)Crural arteries (n=486)* 168 (35%) 142 (29%)

* 486 crural arteries (anterior and posterior tibial, and peroneal) in 162 limbs

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Table XIII. Prediction of performing an infrainguinal PTA procedure by duplexscanning and the outcome measures in patients who did not undergo PTA.----------------------------------------------------------------------------------------------------

Interpretation of duplex findingsOutcome measures PTA No PTA Non-diagnostic----------------------------------------------------------------------------------------------------PTA (n=74) 62/74 (84%) 5/74 (7%) 7/74 (9%)No PTA(n=88) 10/88 (11%) 67/88 (76%) 11/8 (12.5%)

Conservative (n=20) 4/20 (20%) 12/20 (60%) 4/20 (20%)Amputation (n=14) 2/14 (14%) 10/14 (71%) 2/14 (14%)Surgical intervention (n=54) 4/54 (7%) 45/54 (83%) 5/54 (9%)

The accuracy, sensitivity, specificity, negative and positive predictive valuesof duplex scanning in predicting the performance of infrainguinal PTA andthe selection of lesions at various segments for PTA are given in Table XIV.Sixty-two limbs were correctly scheduled for PTA using the findingsobtained from duplex scanning (62/74; 84%). However, in 24 casesundergoing PTA at multiple arterial levels, duplex scanning demonstratedeither non-diagnostic findings or missed lesions in one of the arterialsegments treated by PTA. The accuracy of duplex scanning in the selection offemoropopliteal and crural lesions for PTA was over 85%. However, thesensitivity of duplex scanning in the selection of popliteal and cural lesionsfor PTA was 49% and 38%, respectively, compared with 80% for SFAlesions.

Table XIV. The accuracy, sensitivity, specificity, negative and positive predictivevalues of duplex scanning in predicting performance of infrainguinal PTA and theselection of lesions at various segments for PTA

--------------------------------------------------------------------------------------------Prediction of Accuracy Sensitivity Specificity PPV NPV--------------------------------------------------------------------------------------------Performance of PTA 86% 84% 89% 86% 87%SFA PTA 90% 80% 94% 88% 90%Popliteal PTA 85% 49% 97% 83% 85%Crural PTA 91% 38% 95% 35% 96%

33

DISCUSSION

Femoropopliteal PTAEndovascular intervention is at present generally accepted as an effectivetreatment modality in a substantial proportion of occlusive iliac artery lesions,but in the femoropopliteal segment its role is still the subject of debate (Blair89, Durham 94, Fletcher 86, Martin 99, Jonston 92, Stanley 96, TASC 00,Parson 98). The relative simplicity of the procedure, the possibility of beingable to recanalise long occlusions and the apparently low incidence ofcomplications has encouraged the extension of indications for treatment oflower limb arterial insufficiency. Despite the recent enthusiasm for theprocedure, demonstrated in wide application of PTA in the femoropoplitealsegment, guidelines for selection and factors affecting outcome in limbs withCLI are controversial.

Procedure-related serious complications following PTA of thefemoropopliteal lesions, either mortality or limb loss, have been reported in0–2% of cases (Matsi 94, Hunink 93, Karch 00, Martin 99, Currie 94,Becquemin 94). The 30-day mortality rate was 4.3% in the present study.This is higher than in the previous reports and is possibly due to the inclusionof only those having critical lower limb ischaemia with a substantial numberof elderly patients in poor general health. The early technical success ratevaried between 78–100% in the previous reports, being low in longocclusions compared to short isolated lesions. The technical success rate inthis study was 88%; 75% of failures occurred in those with superficialfemoral artery occlusions 5 cm or more in length. Two patients underwentemergency bypass grafting but no limb loss was directly related to a failedprocedure causing distal embolisation or thrombosis.

Mid- and long-term results of infrainguinal PTA depend on several factors,mainly clinical and anatomic ones. Some studies imply that the results wereworse in limbs with CLI compared to those with claudication (Hunink 93,Albäck 98, London 95). Although the definition of CLI has not been uniformin many of these studies, it should be noted that there are no universallyaccepted guidelines to grade those with severe ischaemic symptoms and anklepressures greater than 50 mm Hg. Subcritical ischaemia might be analternative. In the present study, no attempts beyond the clinical presentationwere made to grade severe ischaemia as subcritical or critical, but those withdisabling claudication without rest pain and/or ulcers were excluded. Hunik et

34

al (1993) demonstrated a 5-year patency rate of 55% in claudicants comparedto 29% in those with CLI. Albäck et al (1998) showed a similar trend inpatients with CLI (patency rates of 61% versus 38% at 2 years).

Of the anatomical factors, the type of lesions dilated and the status of distalrunoff vessels have been pointed out to influence the results offemoropopliteal PTA. A statistically significant difference was noted betweenpatients undergoing PTA for stenosis versus occlusion in several previousstudies (Matsi 94, Hunink 93, Karch 00, London 95, Currie 94, Melliere 01).However, Murray et al (1987) showed that occlusions that can be crossedwith a guide wire have a better patency rate than stenosis. The results of ourstudy showed a significantly worse outcome in limbs with occlusionscompared to those with stenotic lesions. The cumulative primary patency at 5years was only 12% for superficial femoral artery occlusions longer than 5cm in length, compared to 32% for shorter occlusions. On the basis of theseobservations, we consider occlusions longer than 5 cm as unsuitable forconventional PTA.

Subintimal angioplasty has been used with satisfactory results by Bolia et al(1998) even in the treatment of long occlusive lesions, but these excellentresults are yet to be verified by others. The use of thrombolysis in an attemptto reduce the length of occlusion prior to PTA in limbs with chronicocclusions is also controversial with regard to the selection of patients(Weaver 96). A small, randomised trial demonstrated no difference betweenenclosed thrombolysis and PTA versus PTA alone in the treatment offemoropopliteal occlusions (Nicholson 98, Capek 91). Our experience withthrombolysis in chronic occlusions is limited. It was used only in five patientsin the present series with successful outcome only in two cases.

The status of distal runoff has been shown to influence outcome afterfemoropopliteal PTA (Flueckinger 92, Horwath 90, London 95, Sivanthan94, Ray 95). In a study by Albäck et al (1998), the haemodynamic successrate was 60% at 2 years in limbs with good runoff defined by theSVS/ISCVS criteria, compared to 38% in limbs with poor runoff. Thenumber of patent crural arteries or the status of foot vessels did not show anysignificant influence on the patency rates in the present study. It should benoted that the majority of patients in this study had severe infrapopliteal andpedal atherosclerosis and that the numbers in each group are probably notsufficient for an assessment of patency rates and the status of runoff withrespect to the type of lesions dilated.

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The overall patency rate following femoropopliteal PTA in the present studywas lower than in most of the previous reports (Capek 91, Johnston 92,Hunink 93, London 95, Ray 95, Currie 94, Martin 99, Stanley 96, Parsons98, Karch 00, Jackson 01). It is important to note that patency rates in themajority of previous studies were based on the findings obtained mainly fromclinical and haemodynamic evaluations, not routinely on results of duplexscanning or angiography of the dilated segment. It is reasonable to assumethat the real patency rates of the segment where the intervention was mademight be less than the patency rates based on clinical evaluation, as somepatients experienced clinical improvement despite restenosis or occlusion.Nearly 80% of the procedures in the present study were followed by duplexscanning and the majority of patients that did not undergo duplex scanninghad obvious clinical signs of occlusion of the dilated segment in the earlypost-PTA period. Duplex scanning might also have an important role in thedetection of residual stenosis and repeated PTA may extend the interval ofclinical success.

Crural artery PTAThe application of PTA in arteries below the knee initially suffered fromcertain technical disadvantages related to the larger size of catheters requiredto restore an adequate lumen, but the introduction of suitable-sized cathetershafts and balloons in recent years has made it technically possible to dilatestenosis of the crural arteries. With the introduction of a low-friction guidewire it has also been possible to recanalise occluded arteries in the lower leg.

It is generally accepted that crural artery PTA should be performed only inlimbs with CLI. The place of crural artery PTA in limbs with claudication,performed mainly as a combined proximal and distal procedure in order toimprove the distal runoff, is still controversial.

A high technical success rate (88%) and a low complication rate of cruralartery PTA were observed in the present study, and these results are inagreement with other reports (Bolia 94, Durham 94, Schwarten 88, Brown93, Horwath 90, Bakal 90, 96, Saab 92, Bull 92, Sivananth 94, Flueckiger92, London 95, Dorros 90). It seems plausible that the high technical successrate in occluded arteries is related to the small diameter of the occluded cruralartery, which makes it relatively easy to find the thrombosed lumen with aguide wire. The problem of distal embolisation from the site of PTA in thefemoral or popliteal arteries was abolished when the order of PTA procedures

36

was changed. We believe that manipulating catheters and guide wires througha dilated area may dislodge atherosclerotic material. The large groinhaematomas all occurred when large introducers with 2.3mm (7 French)shafts were used early in the series for superficial femoral artery angioplasty.No amputations were directly related to a technical failure of the PTA.

Although the patients in this series were followed with regular ABPImeasurements, the decision on patency was based on categorical improvementin clinical status in those limbs with falsely elevated ankle pressures. Oneshould also be aware of the fact that, especially in those limbs with combinedfemoropopliteal and crural artery PTA, clinical and/or ABPI improvementsdo not necessarily mean that crural arteries are patent. Serial duplex scanning,which has been commonly used in recent years, might offer better follow-upevaluation. It might also be useful for the detection of restenosis.Reintervention before total occlusion in such cases might provide bettersecondary patency rates, as seen in previous reports (Bergamini 95, Lundell95, Vroegindeweij 95, Veith 90).

There is only limited experience of long-term cumulative patency rates ofcrural artery PTA in patients with CLI (TASC 00). The reported limbsalvage rate at 24 months of 60–86% (Wagner 98, Boyer 00, Soder 00,Danielsson 01, Wolfle 00) is well in accordance with the result in the presentstudy (75%).

Our overall primary patency rate of 36% at 36 months might be consideredpoor though, compared with reported patency rates of femorodistal bypassgraftings in patients with CLI (around 80% with vein grafts at 3 years)(Gentile 96, TASC 00, Blair 89,Veith 86, Taylor 90, Martin 99, Parson 98,Hunink 94, Bolia 94, Sanchez 94, Wolfle 00). On the other hand, it should benoted that in this series 20 patients underwent amputation after failed cruralartery PTA without any attempt at distal reconstruction, due to severe distalatherosclerotic involvement; this demonstrates a high-risk group for limb lossthat is not suitable for initial reconstructive surgery. In the present study, thesatisfactory limb salvage rate at 36 months might be overestimated, due to aprobably false definition of CLI solely according to clinical presentationbecause of falsely elevated ankle pressures.

37

Infrapopliteal PTA through infrainguinal graftsInfrainguinal bypass grafting is the most established type of intervention fortreatment of limbs with CLI affecting femoropopliteal and crural arteries.Graft failures occur due to various causes. It is beyond the scope of this thesisto discuss this issue in detail but, in summary, failures in the first month areusually due to technical problems or incorrect patient selection. Between thefirst and 24th month, intrinsic graft lesions either in the graft (vein grafts) or atthe anastomotic sites, irrespective of the graft material, are essentially inducedby myointimal hyperplasia (Davies 94). After two years, progressiveatherosclerotic disease might lead to stenosis or occlusion of the runoffarteries. According to several series, 20–50% of these lesions are responsiblefor haemodynamic failure or graft occlusion (Gutierrez 87, Palumbo 91,McLafferty 95, Bergamini 95, Davies 94, London 93, Grigg 88, Houghton97).

There are no universally accepted guidelines for the detection andmanagement of inflow, graft or runoff-related problems. Atheroscleroticdisease affecting the inflow arteries is usually managed with endovascularintervention, as the results of iliac artery PTA are satisfactory. On the otherhand, surgical interventions are preferred for the treatment of femoral arteryor proximal anastomotic stenosis. The choice of treatment betweenendovascular or surgical intervention, with regard to intrinsic lesions locatedin the graft itself, depends on the time interval after surgery and the policy ofthe centre. Contradictory results have been reported in those with graftstenosis treated by endovascular techniques and it seems that a randomisedstudy is needed (Wittemore 91, London 93, Tonessen 98, Taylor 91,Honghton 97, Perler 90, Gonsalves 99, Hoksbergen 99). The lesions affectingthe distal anastomoses or the runoff vessels that jeopardise the graft patencycan be successfully managed by surgical intervention, mainly by a jump graftto a patent distal artery with a primary patency rate at 3 years of about 80%(Bandyk 91, Sullivan 96, Veith 84, Nehler 94, Avino 99). However, theseprocedures are more technically demanding than the surgical management ofmore proximal lesions and many of these patients do not have suitable veinconduits for reconstruction because of having undergone several operations.Endovascular interventions might be an alternative in those cases and that wasthe reason for the separate analysis of the results of distal PTA throughinfrainguinal bypass grafts in the present study. Previously, few studies, withlimited numbers of patients, have been reported on the use of PTA in therunoff arteries following infrainguinal bypass grafting (Thomson 98, Favre96, London 93, Tonesson 98, Taylor 91, Houghton 97, Perler 90, Sanchez

38

94). In these studies, the results of runoff PTA were difficult to interpret asthe series included graft lesions at other locations and separate analysis wasnot performed. Sanchez et al (1994) have compared patency rates at variouslocations. There was no difference in patency rates at 6 months betweenpatients undergoing PTA at proximal anastomosis, mid graft or distalanastomosis.

The results of this thesis demonstrated a high technical success rate (91%) andno major complications directly related to the procedure. The primarypatency rates following PTA at 12 and 36 months were 41% and 32%,respectively. Several additional PTA procedures were required due torestenosis or reocclusion at the PTA sites in order to achieve 53% primaryassisted patency. Duplex scanning plays an important role in the detection ofthese lesions and surveillance is strongly recommended. Analysis of severalanatomical factors such as the site of PTA, the type of lesion, the status ofrunoff, the presence of diabetes and the use of thrombolysis before PTA inoccluded grafts did not show a subgroup with significantly lower patencyrates. It should be noted that the numbers in each group were limited. Earlyor late failures of PTA did not negatively affect the possibility of performingbypass surgery. Some patients underwent amputation following occlusion ofthe reconstruction, mainly due to extensive distal atherosclerosis, which madesurgical intervention technically impossible.

The present study does not permit any firm conclusion regarding the selectionof treatment modality in infrainguinal grafts with stenotic or occlusive lesionsat the distal anstomosis or in the runoff arteries. We did not attempt tocompare the results of PTA with surgical interventions, due to the fact thatthe severity of lesions in the runoff arteries was not anatomically comparable.During the study period we preferred to perform PTA according to thepreviously mentioned selection criteria as the choice of initial treatment. Aprospective randomised trial might offer better guidelines, but unfortunatelyit is not possible to perform a single-centre study due to the limited numberof patients.

Accuracy of infrapopliteal duplex scanningThe rationale behind noninvasive vascular diagnosis with duplex scanning isfor it eventually to replace diagnostic angiography which has been consideredthe ‘gold standard’ for diagnosis of peripheral vascular disease. Angiographyprovides the necessary information for strategic planning for endovascular orsurgical intervention but, on the other hand, it is invasive and is not without

39

complications (Hessel 81, Bettman 97, Waugh 92, Bonn 96). Satisfactory andreliable arterial mapping of the lower extremity with duplex scanning mightprovide the necessary information for the selection of patients forendovascular interventions or surgical reconstructions without the need forconventional diagnostic angiography.

The experience with duplex scanning for the diagnosis of crural artery lesionsis limited (Moneta 92, Koelemay 98, Larch 97, Ascher 99, Aly 98, Sensier98). Duplex scanning for the evaluation of pedal arteries has not been studiedpreviously. The overall accuracy of cruropedal artery duplex scanning incomparison with selective angiography in this study was 80%. The accuracyof duplex scanning was similar for the crural and pedal arteries. Therelatively low specificity for the peroneal artery is probably due to difficultiesin obtaining satisfactory visualisation of this artery, which is located at adeeper level. This study also demonstrated the feasibility of obtaining reliableevaluation of distal runoff vessels such as the dorsal pedal arteries and plantararch, especially in limbs with CLI and low ankle pressures. The accuracy ofduplex scanning in the crural arteries was slightly lower in study V, despitethe experience of the laboratory and the fact that duplex equipment has beenimproved in recent years. It should be noted that the prospective comparativestudy IV was performed by the most experienced vascular technicians orphysicians. They used the most optimal equipment available in the laboratory.Such optimal conditions are not always obtained for all duplex scans in dailyactivity, for various reasons. The number of patients undergoing lower limbduplex scanning is increasing tremendously and it might be occasionallydifficult to maintain high diagnostic quality in many vascular laboratories.

Selection of patients for infrainguinal PTAAppropriate location of the lesions by duplex scanning permits the use ofselective angiography, such as antegrade puncture of the femoral artery,which eliminates the need for retrograde angiography and PTA can beperformed at the same session. This also lowers the amount of contrast agentgiven during the endovascular procedure as renal insufficiency is a fearedcomplication, especially in patients with elevated serum creatinine levels.Several previous studies have demonstrated the value of duplex scanning inthe selection of patients for PTA at various arterial segments in the lowerextremity (Moneta 92, Karacagil 94, 96, Varty 96, Bodily 96, van der Zaag98, Ascher 99, Schneider 99, Kohler 90, van der Heijden 93, Lai 95,Ramaswami 99, Katsamouris 01, Aly 99). Although the accuracy of duplexscanning was not perfect in some studies, it has been suggested that when the

40

findings were combined with clinical information, it can be safely used as ascreening tool to select appropriate lesions for endovascular procedures. MRangiography has also been successfully used for this purpose (Cambria 97,Wikström 00, Schmiedl 96, Baum 95, Owen 92, Yin 95, Carpenter 92, Levy98, Sarkar 98). It seems that successful application of such noninvasivemodalities in patients with lower limb arterial insufficiency requires aninstitutional validation of MR angiography or duplex scanning againstconventional angiography.

The results of this study demonstrated that duplex scanning can safely be usedfor the selection of patients for infrainguinal endovascular procedures.However, the findings should be interpreted cautiously due to theretrospective nature of the study. Even though the findings obtained fromduplex scanning and angiography were subjected to blind analysis by twodifferent investigators, selection bias could not be completely avoided. Theaccuracy of duplex scanning in the selection of femoropopliteal and crurallesions for PTA was over 85%. However, the sensitivity of duplex scanningin the selection of popliteal and crural lesions for PTA was 49% and 38%,respectively, compared with 80% for SFA lesions. The accuracy of duplexscanning in the diagnosis of multiple distal lesions that were treated by PTAwas relatively low: in 39% of patients who were correctly selected for PTA,duplex scanning misdiagnosed one of the multiple lesions treated by PTA.The number of cases undergoing diagnostic angiography where the lesionswere not amenable to PTA or surgical intervention could be diminished eitherby further experience in duplex scanning or by the use of MR angiography incases that have non-diagnostic duplex scans.

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CONCLUSIONS1. The results of infrainguinal PTA performed for treatment of subcritical or

CLI seemed to be inferior to the results of open surgical interventionsreported in the literature. However, due to the fact that the PTAprocedure does not preclude the performance of bypass grafting, it mightbe an alternative to surgical intervention in limbs with stenotic lesions.PTA might also be considered in patients with high surgical risk andlimited life expectancy, having short occlusive lesions (< 5 cm).

2. PTA at the distal anastomotic site or runoff arteries followinginfrainguinal bypass grafting is technically feasible and offers satisfactorybut inferior results compared to surgical revisions reported in theliterature. As the complications with regard to technical failures did notaffect the possibility of performing surgical intervention, PTA might beconsidered as an alternative for a selected group with suitable lesions.

3. Duplex scanning can safely be used for the selection of patients forinfrainguinal PTA. The sensitivity of duplex scanning in the selection oflesions for PTA was less satisfactory in the popliteal and crural arteriescompared to the superficial femoral arteries.

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ACKNOWLEDGEMENTS

I wish to express my sincere gratitude and appreciation to all persons whohave participated in this project over the years and especially to:

Lars-Erik Lörelius, mentor and dear friend, for introducing me into theintriguing world of intervention, supporting and encouraging me with hisenthusiasm and vivacious sense of humour.

Sadettin Karacagil, friend and supervisor. Without your unfailing energy,endless support and help, this work would never have been completed. Thankyou for always being there.

P-G. Lindgren, for your positive support and consideration that gave me theconfidence to complete this project.

Anders Hemmingsson, co-supervisor, for cheering me on and giving me thevaluable time and advise I needed.

The skilful angiography staff, where the team work is truly vital to thepatient outcome, for all the hours of sweat and blood mixed with laughter.Without your loyalty and commitment this kind of work would never bepossible.

Agneta Besselin, for being a true friend and for helping me with “life-saving”suggestions, for without them, I would still be standing there.

The vascular team and co-authors:Annika Boström, Görel Östholm, Christer Ljungman, David Bergqvist,Anders Hellberg, Bo Westman, Tulga Ulus, Agneta Granbo, Rickard Nymanand Bo Almgren, for all your assistence in data collection, feeding thecomputers with information and extracting results out of the monsters.

Nora Velastegui Pettersson and Håkan Pettersson, for their skillful knowledgewith photographic work and the invaluable assistance, and patience with meduring the final thesis layout.

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Christl Richter-Frohm, for the comforting talks and your expert secretarialwork.

Kate Williams, for the thorough and prompt linguistic corrections.

My mother, Margit Löfberg, for your love and support, and among so muchthe Friday “chats”. They mean a lot to me.

My father, Jan-Harald Löfberg, for giving me his love and affection, for allthe unforgettable memories of the spirited discussions we shared together andfor his genuine interest in my daily work. I miss you so much.

And, of course, my dogs giving me their unrestricted love and devotionregardless of my ups and downs.

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