A Prospective Study of Aggressive Revascularisation in Chronic Lower Limb Ischaemia due to Atherosclerosis
B.L Ravikumar, Jose V. Francisco Menezes
INTRODUCTION
Chronic lower limb ischaemia is identified as intermittent claudication and/or absence of peripheral pulses in lower limbs. The most prevalent cause for chronic lower limb ischaemia is atherosclerosis and prevalence increases with diabetes. [1] It is well known that conditions predisposing to atherosclerosis such as hypertension, diabetes, smoking and hypercholesteremia are associated with endothelial dysfunction. [1, 2] The prevalence of peripheral arterial disease is on rise and prevalence increases with age and thereby morbidity and mortality due to the disease.
During the natural history of chronic lower limb ischaemia symptomatic patients can be divided into two
groups: those with claudication and those with critical limb ischaemia. There is 1%loss of limb yearly in patients suffering from chronic limb ischaemia.[1] 80-90% of salvage of limb is possible by arterial bypass of limbs. Revascularisation is possible in only 50% of patients with critical limb ischaemia.[3]The 1st year mortalityand morbidity of critical limb ischaemia exceeds mostmalignancies with a death rate of 25% and amputation rate of30.[4-7] Advanced radiological technique such as duplex, MRangiogram, has helped to define arterial anatomy more precisely.Percutaneous transluminal angioplasty and saphenous vein graftor dacron or PTFE grafts are standard methods of treatment.[8,9]With ever increase in number of patients , need to devise methodswhich are not only effective but also prolong quality of life. It hasbeen seen that limb salvage is more successful than lifeprotection. Revascularisation improves the limb salvage with noeffect on survival.
MR – Magnetic Resonance
PTFE – Polytetrafluoroethylene
ABI – Ankle brachial index
METHODS
Prospective study of 40 cases of chronic lower limb ischaemia due to atherosclerosis admitted in Kempegowda Institute of Medical Sciences and Research Centre, Bangalore from November 2007 to October 2009. All patients were aged above 45 years. Patients with stenotic lesions, acute limb ischaemia, Buerger’s disease, Raynaud’s disease, inflammatory arteritis and collagen vascular disease were excluded from the study. A detailed history
regarding age, sex, duration symptoms was taken from the patient and past history regarding smoking, hypertension, ischemic heart disease, hypercholesteremia, diabetes was stressed upon. Examination of peripheral pulses and cardia was done. Different clinical features such as ulceration, gangrene, rest pain and disabling claudication were noted. Depending on thisrevascularisation was done. Preoperative evaluation of patient forrevascularisation included calculation of ankle brachial index, arterial doppler ultrasound, MR angiography or conventional angiography.
Postoperative assessment with respect to graft rejection, graftinfection, intensive care and other complications were included. The follow up period was for 12 months after surgery.Clinically pulse examination and Ankle Brachial Index (ABI) wascalculated at 3, 6 and 12 months. If these were not detected or ifpatient was symptomatic a duplex scan was done and if graftfailure was detected then angiography was done.
Statistics:
Descriptive statistical analysis was carried out.Results on continuous measurements are presented on Mean SD
(Min-Max) and results on categorical measurements arepresented in Number (%). Significance is assessed at 5 % level ofsignificance. 95% Confidence Interval has been computed to findthe significant features. Patency and limb salvage analysis wasperformed using SPSS for Kaplan Meir survival analysis as wellas x2 analysis.Ap value less than 0.05 was significant where as pvalue 0.05-0.10 was suggestive of significance.
RESULTS
Total number of patients (n) in our study was 40. Sex distribution: 38 (95%) males and2 (5%) females. The age distribution was in the range of 45 yearsto 80 years with a mean ± SD; 58.57 ± 8.85. In this study;14(35%) patients underwent revascularisation for left limb, 21(52.5%)patients for right limb and 5(12.5%) for both.
Of the 40 Patients 16(40%) presented with disablingclaudication, 8(20%) patients with purely rest pain. Ischaemic
ulcers were present in 7(17.5%) patients and gangrene of theforefoot in 11(27.5%) patients. Patients with ischemic ulcers andgangrene had associated rest pain or disabling claudication. Mostof the patients 36 (90%) presented to us within 6 months of theircomplaints.The commonest physical finding in our study was pregangrene in 22(52.5%) patients. This was due to earlypresentation. The other signs in our study were ulceration in11(27.5%) patients and gangrene in 7 (17.5%) patients.Most common risk factors(Table 1) were smoking andhypertension. All Patients underwent routineinvestigations including fasting blood sugar levels and lipidprofile. Fasting blood sugars were more in 45% of the patientssuggesting that poor control of diabetes is predisposing toperipheral vascular disease. Lipid profile was deranged in almost35% of the patients.Duplex scanning and Angiogram were done in all
patients before the procedure. Angiogram is only done if thepatient is being planned for interventional procedure. Based onthe report - level of block was noted & the decision regarding thesite of proximal and distal anastomosis was taken. The caliber ofthe arteries and distal run off was also noted .We noted Femoro-Popliteal occlusive disease in21(52.5%) patients, aortoiliac disease in 14(35%) where asInfrapoppliteal occlusive disease compounded to 5(12.5%)patients. Commonest indication for intervention was tissue loss(Table 2).Of the 40 patients 14(35%) patients underwent bypassfor aortoiliac disease where as 26(65%) underwent bypass forinfrainguinal disease. Of the 26 patients majority of the bypasswere Femoro-Popliteal bypasses in 17(42.5%) patients (Table 3).The distal anastomotic site was based on the reformation of theartery on angiogram. In 2 patients multiple procedures were
done. Dacron graft was used in cases of aortoiliac disease. Mostcommon graft material used was ePTFE i.e. in 21(52.5%) ofpatients. Wherever saphenous vein was available it was theconduit of choice for infrainguinal disease i.e. in 10 (25 %)patients.The above Patients were followed up on the outpatientbasis at intervals of 3, 6 & 12 months by pulse examinationand Ankle Brachial Index.Post operatively the graft pulsations were goodclinically and ABI was more than 0.8 in all 35 patients till the endof follow up period without any interventions. Colour Duplexscan was done only in 13 cases during the follow up with p valueof 0.02 showing that ABI is good indicator for follow up (Table4). Otherwise the graft pulsations and hand held Doppler wasdone on every follow up. If these did not pick up pulsations thenDuplex and Angiography were done and appropriate interventioncarried out. These patients were put on regular antiplatelet agents.Life table curves for primary patency, secondary patency, limb
salvage were drawn. Overall Primary patency, Secondarypatency and Limb salvage rates were 82.5%, 87.5% and 87.5%respectively (Figure 1, 2, 3). Life table analysis showed that doingre-surgery in graft thrombosis help in salvaging limb significantlywith p value of 0.08. Also p value of 0.08 for limb salvage rate alsoshows that revascularisation is safe and effective for salvage oflimbs.
Primary Patency rates: -
Out of the 40 patients, 33 of the patients had patent graftsat the end of 12 months primarily (without any intervention) i.e.82.5% (Figure 1).
Secondary Patency rate:-
There were 3 (7.5%) patients who requiredthrombectomy. There grafts were salvaged and the limb was
saved. They had patent grafts at the end of 12 months of follow up.The secondary patency rate at 1 year includes the primary patencyrates + the salvaged grafts. i.e. 33 +2 = 35 (87.5%).This is theoverall patency rate of the study is 87.5% at the end of 1 year (Figure 2).7(17.5%) of the grafts had thrombosis and graftinfection during the follow up period. These patients came withrecent onset of rest pain and pregangrenous changes. Only3(7.5%) of the grafts could be salvaged by thrombectomy. All ofthese patients underwent angiogram to confirm the block of
grafts. They had patent grafts during follow up of 12 months andtheir limbs could be salvaged.There were 4(10%) grafts that had failed and graftscould not be salvaged by thrombectomy and the limb had to beamputated (Table 5). Out of these; 3 patients had Below KneeAmputation and 1 had above knee amputation.In toto there were 11(27.5%) amputations done in ourstudy. There were 3 below knee amputations, 1 above kneeamputation, 1 Transmetatarsal and 6 toe amputations. The Aboveknee and Below Knee amputations are not included under the
limb salvage. Limb salvage rate in our study was 87.5% (Figure3).9 (22.5%) of our patients required intensive post
operative care ranging from 2-10 days depending upon comorbidities. Most of the patients who required Intensive care hadaorto-iliac disease. We had 1 (2.5%) mortality. The patient hadpost operative myocardial infarction on 5th day after graftsalvation
DISCUSSION
Chronic lower limb ischaemia is a ubiquitous conditionwith an increasing incidence. Over 25% of Critical limbischaemia patients will require major amputation, butreconstructive arterial surgery improves limb salvage. [10] Patientswith critical limb ischaemia represent about 10% of the totalnumber of ischaemic patients [11]. In patients with severe legischaemia, revascularization produces a superior quality of lifethan amputation.Arterialreconstruction for chronic limb ischaemia hasbecome increasingly successful with regard to long termpalliation of disabling claudication and salvage of limbsthreatened with critical ischaemia.Pre-operative evaluation involves not just the limb, asthere is significant co-morbidity involved in the form ofcardiovascular and cerebrovascular atherosclerosis.The best form of non-invasive evaluation of the lowerextremity is the colour duplex scan. Comprehensive preoperativeangiogram remains the gold standard procedure foroptimal delineation of the patients’ vascular anatomy and decisionmaking.Several studies have been published critically assessingthe current study of bypass grafting for critical limb ischaemia.These studies have shown that unsuccessful functional outcomesare often predetermined by intrinsic preoperative comorbidfactors and not by the operative treatment. Treatment outcomesfor critical lower limb ischaemia vary from study to studyaccording to the patients with rest pain and tissue loss; aproportion rarely disclosed in most outcome studies. [12] Most of the studies[12, 13, 14, 15] had similar medianage group.In our study, demographic risk factors were consistentwith Taylor et al[12], Healey[15] and BASIL[16] study with 95% confidence intervals within the range except cerebrovascularaccidents which were less. Smoking cessation is the mostimportant tenet of therapy and even with best and latestefforts,cessation occurs in 20-40% of patients in short term[17,18].The various indications for bypass in the present studywere consistent with other studie[12,19] and were within 95% confidence limits. Thedisease strata of angiographic distribution of disease matched tothe studies of Taylor[12] and Kalbaugh[20].In our study we have done the pulse examination & handheld Doppler examination of all the 40 patients during theirspecified follow-up of 3, 6 & 12 months. Duplex examination ofthe patients has been done when specifically required- a) whenpulse and hand held Doppler do not pick up signals/ patient hassymptoms of occlusion of the graft, b) follow up of salvagedgrafts. 13 of the patients in the study group were on regular followup with duplex. Angiography has specifically been done whenthe graft is occluded to know the level of occlusion. (It wasrequired in graft failures-7 grafts) Studies have shown that
follow up with duplex scan is the ideal way of monitoring thegraft patency.The results of our study are consistent with the studiesconducted by Taylor et al[12], Cull[14], Healey[15], BASIL[16],Kalbaugh[20] and Awad et al [21] trials with p value of 0.08 forcumulative secondary patency rate and limb salvage rate. 95 %confidence intervals were within the range of other studies forprimary patency rate, secondary patency rate and limb salvagerate i.e.(95% CI 68.05-91.25, 73.89-94.54, 73.89-94.54)respectivelyThere were 7 graft failures in our study. 3 grafts weresalvaged by thrombectomy and 4 underwent amputation (3below knee, 1 above knee). Although many studies havedemonstrated that autologous veins have the best patency rates itis seen that in Indians the veins are smaller in diameter andcaliber. When the patient has major co-morbid factors and thesurgery has to be done in lesser time then artificial grafts are thebest. Above knee Femoropopliteal bypass has good flow in thegrafts and patency rate is comparable with that of autogenousvein grafts. The apparent high patency rate in our study may be due to small sample size and only short term follow up i.e. 1 yearfollow up.The morbidity rates in our study has been 20% with 2cases of myocardial infarction, 3 had wound infection and 3patients developed pneumonia. This is very less as compared toother major studies. One patient died during the post-operativeperiod (Mortality-2.5%) and there were no deaths in follow upperiod. Studies have shown mortality in the same range of 1-8%12. Patients were relieved from pain due to ischaemic ulcers andgangrene. They were self-reliant and were able to carry theirroutine work, which was not possible before the surgery. Patientswho had amputations were given required physiotherapy.
CONCLUSION:
Revascularisation for peripheral vasculardisease is safe and effective for salvage of limbs with disablingclaudication and critical limb ischaemia. Chronic lower limbischaemia due to atherosclerosis is quite a common condition. Pre operative angiography is helpful in planningmanagement. Post operatively ankle brachial index co-relateswith symptoms. Early aggressive management is helpful inpreventing amputation. An initial attempt at reconstruction isindicated in all limbs, except when amputation is inevitable.Complications of the surgery in these patients are due toassociated involvement of coronary arteries, cerebral arteries asvascular disease is a diffuse involvement of the blood vessels. Poor control of risk factors such as diabetes, hypertension
and smoking may result in graft failure.
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LIST OF TABLES AND FIGURES
Table 1 Risk factors
Table 2 Indications for intervention
Table 3 Surgical procedures performed
Table 4 Results of 1 year follow up
Table 5 Complications of various procedures