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 mortality and
morbidity of critical limb ischaemia exceeds most malignancies with a death rate of 25% and amputation rate of
30.[4-7] Advanced radiological technique such as duplex, MR angiogram, has helped to define arterial anatomy more
precisely. Percutaneous transluminal angioplasty and saphenous vein graft or dacron or PTFE grafts are standard
methods of treatment.[8,9] With ever increase in number of patients , need to devise methods which are not only
effective but also prolong quality of life. It has been seen that limb salvage is more successful than life protection.
Revascularisation improves the limb salvage with no effect 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 this revascularisation was done. Preoperative evaluation of patient for revascularisation included
calculation of ankle brachial index, arterial doppler ultrasound, MR angiography or conventional angiography.
Postoperative assessment with respect to graft rejection, graft infection, 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) was calculated at 3, 6 and 12 months. If these were not detected or if patient was symptomatic a duplex
scan was done and if graft failure 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 are presented in Number (%). Significance is assessed at 5 %
level of significance. 95% Confidence Interval has been computed to find the significant features. Patency and limb
salvage analysis was performed using SPSS for Kaplan Meir survival analysis as well as x2 analysis. A p value less
than 0.05 was significant where as p value 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 years to 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 disabling claudication, 8(20%) patients with purely rest pain. Ischaemic
ulcers were present in 7(17.5%) patients and gangrene of the forefoot in 11(27.5%) patients. Patients with ischemic
ulcers and gangrene had associated rest pain or disabling claudication. Most of the patients 36 (90%) presented to us
within 6 months of their complaints.The commonest physical finding in our study was pregangrene in 22(52.5%)
patients. This was due to early presentation. The other signs in our study were ulceration in 11(27.5%) patients and
gangrene in 7 (17.5%) patients. Most common risk factors(Table 1) were smoking and hypertension. All Patients
underwent routine investigations including fasting blood sugar levels and lipid profile. Fasting blood sugars were
more in 45% of the patients suggesting that poor control of diabetes is predisposing to peripheral vascular disease.
Lipid profile was deranged in almost 35% of the patients.Duplex scanning and Angiogram were done in all
patients before the procedure. Angiogram is only done if the patient is being planned for interventional procedure.
Based on the report - level of block was noted & the decision regarding the site of proximal and distal anastomosis
was taken. The caliber of the arteries and distal run off was also noted .We noted Femoro-Popliteal occlusive disease
in 21(52.5%) patients, aortoiliac disease in 14(35%) where as Infrapoppliteal 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 bypass for aortoiliac disease where as 26(65%) underwent bypass for infrainguinal disease. Of
the 26 patients majority of the bypass were Femoro-Popliteal bypasses in 17(42.5%) patients (Table 3). The distal
anastomotic site was based on the reformation of the artery on angiogram. In 2 patients multiple procedures were
done. Dacron graft was used in cases of aortoiliac disease. Most common graft material used was ePTFE i.e. in
21(52.5%) of patients. Wherever saphenous vein was available it was the conduit of choice for infrainguinal disease
i.e. in 10 (25 %) patients. The above Patients were followed up on the outpatient basis at intervals of 3, 6 & 12
months by pulse examination and Ankle Brachial Index. Post operatively the graft pulsations were good clinically
and ABI was more than 0.8 in all 35 patients till the endof follow up period without any interventions. Colour
Duplex scan was done only in 13 cases during the follow up with p value of 0.02 showing that ABI is good indicator
for follow up (Table4). Otherwise the graft pulsations and hand held Doppler was done on every follow up. If these
did not pick up pulsations then Duplex and Angiography were done and appropriate intervention carried out. These
patients were put on regular antiplatelet agents. Life table curves for primary patency, secondary patency, limb
salvage were drawn. Overall Primary patency, Secondary patency and Limb salvage rates were 82.5%, 87.5% and
87.5% respectively (Figure 1, 2, 3). Life table analysis showed that doing re-surgery in graft thrombosis help in
salvaging limb significantly with p value of 0.08. Also p value of 0.08 for limb salvage rate also shows that
revascularisation is safe and effective for salvage of limbs.
Primary Patency rates: Out of the 40 patients, 33 of the patients had patent grafts at 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 required thrombectomy. 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 patency rates + the salvaged grafts. i.e. 33 +2 = 35 (87.5%).This is the overall 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 graft infection during the follow
up period. These patients came with recent onset of rest pain and pregangrenous changes. Only 3(7.5%) of the grafts
could be salvaged by thrombectomy. All of these patients underwent angiogram to confirm the block of
grafts. They had patent grafts during follow up of 12 months and their limbs could be salvaged. There were 4(10%)
grafts that had failed and grafts could not be salvaged by thrombectomy and the limb had to be amputated (Table 5).
Out of these; 3 patients had Below Knee Amputation and 1 had above knee amputation. In toto there were
11(27.5%) amputations done in our study. There were 3 below knee amputations, 1 above knee amputation, 1
Transmetatarsal and 6 toe amputations. The Above knee and Below Knee amputations are not included under the
limb salvage. Limb salvage rate in our study was 87.5% (Figure 3). 9 (22.5%) of our patients required intensive post
operative care ranging from 2-10 days depending upon co morbidities. Most of the patients who required Intensive
care had aorto-iliac disease. We had 1 (2.5%) mortality. The patient had post operative myocardial infarction on 5th
day after graft salvation
DISCUSSION
Chronic lower limb ischaemia is a ubiquitous condition with an increasing incidence. Over 25% of Critical limb
ischaemia patients will require major amputation, but reconstructive arterial surgery improves limb salvage. [10]
Patients with critical limb ischaemia represent about 10% of the total number of ischaemic patients [11]. In patients
with severe leg ischaemia, revascularization produces a superior quality of life than amputation. Arterial
reconstruction for chronic limb ischaemia has become increasingly successful with regard to long term palliation of
disabling claudication and salvage of limbs threatened with critical ischaemia. Pre-operative evaluation involves not
just the limb, as there is significant co-morbidity involved in the form of cardiovascular and cerebrovascular
atherosclerosis. The best form of non-invasive evaluation of the lower extremity is the colour duplex scan.
Comprehensive preoperative angiogram remains the gold standard procedure for optimal delineation of the patients’
vascular anatomy and decision making. Several studies have been published critically assessing the current study of
bypass grafting for critical limb ischaemia. These studies have shown that unsuccessful functional outcomes are
often predetermined by intrinsic preoperative comorbid factors and not by the operative treatment. Treatment
outcomes for critical lower limb ischaemia vary from study to study according to the patients with rest pain and
tissue loss; a proportion rarely disclosed in most outcome studies. [12] Most of the studies [12, 13, 14, 15] had similar
median age group. In our study, demographic risk factors were consistent with Taylor et al[12] , Healey[15] and
BASIL[16] study with 95 % confidence intervals within the range except cerebrovascular accidents which were less.
Smoking cessation is the most important tenet of therapy and even with best and latest efforts,cessation occurs in 2040% of patients in short term[17,18] .The various indications for bypass in the present study were consistent with other
studie [12,19] and were within 95% confidence limits. The disease strata of angiographic distribution of disease
matched to the studies of Taylor[12] and Kalbaugh [20].In our study we have done the pulse examination & hand held
Doppler examination of all the 40 patients during their specified follow-up of 3, 6 & 12 months. Duplex
examination of the patients has been done when specifically required- a) when pulse and hand held Doppler do not
pick up signals/ patient has symptoms of occlusion of the graft, b) follow up of salvaged grafts. 13 of the patients in
the study group were on regular follow up with duplex. Angiography has specifically been done when the graft is
occluded to know the level of occlusion. (It was required in graft failures-7 grafts) Studies have shown that
follow up with duplex scan is the ideal way of monitoring the graft patency. The results of our study are consistent
with the studies conducted 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 for cumulative secondary patency rate and limb salvage rate. 95 % confidence intervals were
within the range of other studies for primary patency rate, secondary patency rate and limb salvage rate i.e.(95% CI
68.05-91.25, 73.89-94.54, 73.89-94.54) respectively There were 7 graft failures in our study. 3 grafts were salvaged
by thrombectomy and 4 underwent amputation (3 below knee, 1 above knee). Although many studies have
demonstrated that autologous veins have the best patency rates it is seen that in Indians the veins are smaller in
diameter and caliber. When the patient has major co-morbid factors and the surgery has to be done in lesser time
then artificial grafts are the best. Above knee Femoropopliteal bypass has good flow in the grafts and patency rate is
comparable with that of autogenous vein 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 year follow up. The morbidity rates in our study has been 20% with
2 cases of myocardial infarction, 3 had wound infection and 3 patients developed pneumonia. This is very less as
compared to other major studies. One patient died during the post-operative period (Mortality-2.5%) and there were
no deaths in follow up period. Studies have shown mortality in the same range of 1-8 %12. Patients were relieved
from pain due to ischaemic ulcers and gangrene. They were self-reliant and were able to carry their routine work,
which was not possible before the surgery. Patients who had amputations were given required physiotherapy.
CONCLUSION:
Revascularisation for peripheral vascular disease is safe and effective for salvage of limbs with disabling
claudication and critical limb ischaemia. Chronic lower limb ischaemia due to atherosclerosis is quite a common
condition. Pre operative angiography is helpful in planning management. Post operatively ankle brachial index corelates with symptoms. Early aggressive management is helpful in preventing amputation. An initial attempt at
reconstruction is indicated in all limbs, except when amputation is inevitable. Complications of the surgery in these
patients are due to associated involvement of coronary arteries, cerebral arteries as vascular 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