Scandinavian Journal of Surgery 93: 57–60, 2004
SURGICAL TREATMENT OF POPLITEAL ARTERY ANEURYSMS E. Laxdal, S. R. Amundsen, E. Dregelid, G. Pedersen, S. Aune Department of Vascular Surgery, Haukeland University Hospital, Bergen, Norway
ABSTRACT
Objectives: To report the results of surgical treatment of popliteal aneurysms with respect to symptoms and aneurysm size. Design: A retrospective study based on prospectively registered data, in a single vascular unit. Patients and Methods: Forty-nine patients were subjected to 57 operations from May 1974 to June 2000. Patency and limb salvage rates are compared for limbs with and without symptoms of ischaemia, and for small (2 cm or less) and large (> 2 cm) aneurysms. The long-term survival rate was calculated and compared with that of an age and sexmatched population. Results: The overall 5 year graft patency was 60 %. It was 83 % for asymptomatic limbs and 49 % for limbs with ischaemic symptoms. This difference was significant (p < 0,05). The overall 5 year limb salvage rate was 76 %. It was 100 % for asymptomatic and 64 % for symptomatic limbs and this difference was significant (p < 0,05). Twenty-one of the aneurysms were 2 cm or less in diameter and 85 % of these caused symptoms of ischemia. The operative mortality was 4 %. The 5-year survival rate was 57 % and significantly lower than that of a demographically matched population. Conclusion: The results of prophylactic operations for popliteal aneurysms on asymptomatic limbs are significantly better than those of operations done on limbs with ischaemic symptoms. The aneurysm size at which to recommend surgery is still not settled. Key words: Aneurysm; popliteal artery; surgery
INTRODUCTION Although uncommon, popliteal aneurysms have to be taken into consideration as a cause of intermittent claudication or critical ischaemia, especially in male patients with aneurysm of aorta or other arteries (1, 2, 3). It is not the danger of rupture, but of distal thromboembolism with the resulting threat to the limb that is of main concern here. Amputation rates of 20 to 36 % have been reported in cases of thrombosed popliteal aneurysms (4, 5, 6). The risk of distal Correspondence: Elin Laxdal, M.D. Department of surgery Haukeland University Hospital N - 5021 Bergen Norway Email:
[email protected]
thromboembolism is thought to increase with aneurysm size (7). Early diagnosis and treatment of asymptomatic popliteal aneurysms have therefore been recommended, although the lower size limit of asymptomatic aneurysms at which to recommend surgical treatment has not been clarified (2, 3, 8, 9). The aim of the present study is to report the results of operative treatment of popliteal aneurysms with focus on symptoms and aneurysm size. MATERIAL AND METHODS Information on all operations for popliteal aneurysms performed at our unit were obtained from the vascular registry of Haukeland University Hospital and the patient records. In the period between May 1974 and June 2000, 49 patients were subjected to operations on 57 limbs. There were
58
E. Laxdal, S. R. Amundsen, E. Dregelid, G. Pedersen, S. Aune TABLE 1
Comorbidities in 49 patients operated for popliteal aneurysms. Reliable information on smoking could not be retrieved in all cases. Condition
Number
Heart disease Hypertension Diabetes mellitus Stroke Smoking
22/49 17/49 02/49 04/49 22/44
TABLE 2 Aneurysms at other sites in 49 patients operated for popliteal aneurysms. Site Aortic aneurysms Contralateral popliteal artery Iliacal aneurysms Common femoral artery Visceral aneurysms
Number
%
17 21 09 04 02
35 43 18 08 04
TABLE 3 Symptoms caused by 57 popliteal aneurysms in 49 patients. Symptoms
Number
Asymptomatic Intermittent claudication Critical ischemia Pressure without occlusion or rupture Pressure with rupture
17 06 28 02 04
Total
57
46 men and 3 women. The mean age was 69 years (range 33–88 years). Comorbidities are illustrated in table 1. The occurrence of concurrent aneurysms at other sites is illustrated in table 2. Bilateral popliteal aneurysms were found in 21 cases. Three patients had previously suffered a major amputation of the contralateral limb because of irreversible ischaemia caused by a thrombosed popliteal aneurysm. Aortic or aortoiliac aneurysms were found in 17 patients and common femoral in four and visceral aneurysms in two. Eight patients had earlier been operated on for abdominal aortic aneurysms. In the early years the diagnosis was based on preoperative finding of a pulsating mass in the popliteal region verified by angiography or the incidental finding of an aneurysm during surgery. Later, preoperative assessment of aneurysm size and the quality of outflow arteries was done with ultrasound and angiography. The popliteal artery was considered aneurysmatic if the diameter exceeded 50 % of the adjacent normal artery (10). Small aneurysms with a diameter of 2 cm or less were usually not operated on unless causing symptoms. Seventeen of the treated limbs were asymptomatic. Ischaemic symptoms were found in 34 limbs, whereof 28 had symptoms of critical ischaemia and six had intermittent claudication. Two aneurysms caused pressure symptoms only. Four aneurysms were ruptured at the time of diagnosis (Table 3).
The standard operative method was exclusion of the aneurysm through a medial approach followed by a saphenous vein or prosthetic bypass. The vein was either reversed or left in situ. A prosthetic conduit was used when no vein was available. In cases with ischaemic symptoms, thrombectomy of the leg arteries was attempted. Fifty-one limbs were treated with a venous bypass, 42 with reversed vein and nine with the saphenous vein in situ. Four prosthetic bypasses were done to the distal popliteal artery and two to the proximal popliteal artery. Follow-up was not done routinely in the early years. From 1993 graft surveillance with duplex ultrasound scanning was done one, three, six and twelve months postoperatively and yearly thereafter. In cases of graft occlusion, secondary procedures were discussed and decided on individually, based on the symptoms caused by the graft occlusion and the general condition of the patient. Operative mortality was defined as death within 30 days. The mean follow-up time with respect to patency was 42 months (range 0–197 months). The mean follow-up time with respect to survival was 72 months (range 0–313 months). Survival analysis was done with the product limit method and illustrated with Kaplan–Meier curves. The logrank test was used for comparison of graft patency and limb salvage between groups (SPSS 9.0 for Windows). Observed and expected survival was compared with the MantelHaenzel test. Chi-square test was used for comparison of preoperative symptoms and postoperative results for small (≤ 2 cm) and larger (> 2 cm) aneurysms. p values < 0.05 were accepted as significant.
RESULTS The operative mortality rate was 4.1 %. One patient died of stroke and one of myocardial infarction. The overall 5 year graft patency rate was 60 %. The 5-year graft patency rate was 83 % for asymptomatic limbs and 49 % for limbs with symptoms of ischaemia. This difference was statistically significant (p = 0.02) (Fig. 1). The overall 5-year limb salvage rate was 76 %. The 5-year limb salvage rate was 100 % for limbs without symptoms of ischaemia and 64 % for cases with ischaemic symptoms and this difference was also significant (p < 0.05) (Fig. 2). Information on the aneurysm size was available in 55 cases. The mean size was 3.5 cm (range 1.5–10 cm). Twenty-two aneurysms had a diameter of 2 cm or less, of whom eighteen caused ischaemic symptoms and 7 resulted in amputation. Thirty-three aneurysms were larger than 2 cm, of whom 17 caused ischemic symptoms and 4 ended up with a major amputation. Comparison of the two groups with regard to patency and limb salvage rates revealed a small difference which was not significant. The 5-year survival rate 57 %, whereas the expected survival of an age and sex matched population was 73 %. This difference was statistically significant (p < 0.05). DISCUSSION Although popliteal aneurysms account for up to 84 % of the peripheral aneurysm (11), they are not so frequently encountered by vascular surgeons in gener-
Popliteal artery aneurysms; surgery
59
Limb salvage
1,0 A
,9
,9
,8
17
,7
16
13
11
11
10
9
7
A
1,0 16
14
10
9
9
8
8
7
6
,8
6
,7
,6
B
,5
B
,6
20
,5 22
,4
18
17
15
13
9
9
8
8
16
15
14
12
8
8
8
7
,4
,3
,3
,2
,2
P = 0.02
,1
P = 0.02
,1 0,0
0,0 0
12 6
Months
24 18
36 30
48 42
60
0
54
6
12
18
24
30
36
42
48
54
60
Months
P = 0,0235
Fig. 1. Results of operations on 57 limbs for popliteal artery aneurysms. Comparison of 5 years cumulative patency rates in limbs without (A) and with (B) symptoms of ischaemia. The numbers under the curves indicate patients at risk.
Fig. 2. Results of operations on 57 limbs for popliteal artery aneurysms. Comparison of 5 years cumulative limb salvage rates in limbs without (A) and with (B) symptoms of ischeamia.
al. (12). The scarcity of cases limits the possibility of systematic research with randomised clinical trials. Previous reports on popliteal aneurysms are mostly based on retrospective studies with a time span of decades. Only one prospective multicentre study on the subject has been published. This study presented data systematically collected by 19 vascular surgeons on surgical or conservative treatment of 137 patients with 200 popliteal aneurysms over a period of 4 years (7). The overall five-year graft patency and limb salvage rates in our study of 60 % and 76 % respectively are comparable to the results reported by other centres (12). It has been advocated that asymptomatic popliteal aneurysms with diameters exceeding 2 cm in good–risk patients, should be treated surgically in order to prevent thrombosis and subsequent embolism with development of irreversible distal ischaemia (12). In the present study, the results of operative treatment of asymptomatic cases with respect to limb salvage rates and graft patency rates were significantly better than in limbs with ischaemic symptoms, and thus in support of this view. There were no limb losses as a result of graft occlusions in the asymptomatic cases. These findings correspond to previous reports and support a liberal attitude towards surgical treatment (1– 8, 13, 14). The treatment of small (< 2 cm) asymptomatic aneurysms is still a matter of controversy (3, 7). Varga and colleagues found a significantly larger diameter of aneurysms with a mural thrombus, as compared to aneurysms without thrombus (2.9 cm vs. 2.15 cm). This relation between thrombus formation and aneurysm size was the authors’ argument for an expectant attitude towards small asymptomatic aneurysms. However, others have reported an unfavourable natural history of all popliteal aneurysms. Limb threatening complications in up to 57 % of limbs with asymptomatic aneurysms during a mean follow up of 18 months and 74 % after 5 years have been re-
1,0 ,9
B
,8 ,7
A
,6 ,5 ,4
43
,3
40
36
35
31
31
29
24
22
,2
P < 0,05
,1 0,0 0
12 6
24 18
36 30
48 42
60 54
Fig. 3. Observed (A) and expected (B) survival in 49 patients operated for popliteal aneurysms.
ported (3). These findings are supportive of a more aggressive policy advocating preventive surgery of all popliteal aneurysms (5, 8, 14 –16). There are few studies that focus on the relationship between symptoms and aneurysm size. Szilagyi et al. (1) found that aneurysms with a diameter smaller than 2 cm were significantly less associated with symptoms of ischaemia than larger aneurysms. This material included an observation of conservatively treated asymptomatic aneurysms, the majority of which were classified as small. In our study, twentytwo of 57 aneurysms (37 %) had a diameter of 2 cm or less. Eighteen (85 %) of these caused ischaemic symptoms leading to an amputation in 7 cases. Seventeen of the 33 aneurysms larger than 2 cm caused ischaemic symptoms, resulting in amputation in four cases only. In our study, a significant association between size and ischaemic symptoms, patency or limb survival could not be demonstrated. This comparison is biased partly because of the fact that conserv-
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E. Laxdal, S. R. Amundsen, E. Dregelid, G. Pedersen, S. Aune
atively treated small aneurysms are not included in our study and partly because of a conservative approach towards small asymptomatic aneurysms at our institution, resulting in a higher proportion of symptomatic small aneurysms in our group of patients. However, the fact that more than one third of our series collected through a period of 26 years consists of small (< 2 cm) aneurysms implies that small aneurysms should not be regarded as harmless. The recent advances in thrombolytic therapy have been used as an argument against a liberal approach to asymptomatic popliteal aneurysms, advocating an expectant attitude until symptoms appear (18, 19). The use of preoperative thrombolysis in limbs with symptoms of ischaemia has been shown to improve the outcome to some degree, but it has not been proven to eliminate the risk of ischaemic threat to the limb. Thrombolysis with streptokinase is found to be ineffective in those treated 10 or more days after the occurrence of the first ischaemic symptoms (18). Another study reported of preoperative thrombolytic therapy of 18 cases with symptoms of critical ischaemia, which failed in five cases, all of whom ended up with a major amputation (7). Those results indicate that thrombolytic therapy does not solve the limb-threatening problem of symptomatic popliteal aneurysms and does not justify an expectant policy for asymptomatic aneurysms (7, 17–19). The reason for this may be the silent embolisation resulting in gradual destruction of the subpopliteal arteries, causing symptoms only when the circulation has deteriorated irreversibly. Furthermore, thrombolytic therapy in itself is not without complications and is contraindicated in patients with severe symptoms of acute ischaemia. The 5-year survival rate of our patients is similar to that of patients with critical ischaemia (17). Dawson reported a similar 5-year survival rate in a retrospective study of 50 patients with popliteal aneurysms (3). In his series, the presence of multiple aneurysms was an independent risk factor for death, which in the majority of cases was caused by a myocardial infarction. We could not document any significant association between mortality and risk factors, possibly explained by the limited number of patients in our study. We conclude, that prophylactic operations for asymptomatic popliteal aneurysms in good-risk patients can be recommended, although the lower size limit for treatment has not been clarified. The results of our study indicate that small asymptomatic popliteal aneurysms should not be ignored. The poor relative long-term survival of these patients who suffer from an asymptomatic and not life threatening condition may keep many surgeons on the conservative side. We find that small popliteal aneurysms without signs of mural thrombus should be followed with duplex-ultrasound to detect growth and thrombus formation and doppler – pressure measurement to
detect deterioration of crural arteries, supplied with angiography in selected cases. Further studies on the usefulness of anticoagulation or antipatelet therapy to minimise the damage of distal thromboembolism are needed. REFERENCES 01. Szilagyi DE, Schwartz RL, Reddy DJ: Popliteal arterial aneurysms. Their natural history and management. Arch Surg 1981;116:724–728 02. Shortell CK, DeWeese JA, Ouriel K, Green RM: Popliteal artery aneurysms: A 25-year surgical experience. J Vasc Surg 1991;14:771–779 03. Dawson I, van Brockel JH, Brand R, Terpstra JL: Popliteal artery aneurysms. Long – term follow- up of aneurysmal disease and results of surgical treatment. J Vasc Surg 1991;13:398– 407 04. Reilly MK, Abbot WM, Darling RC: Aggressive surgical management of popliteal aneurysms. Am J Surg 1983;145:498–502 05. Vermilion BD, Kimmins SA, Pace WG, Evans WE: Reviews of one hundred and forty-seven popliteal aneurysms with long term follow up. Surgery 1981;90:1009–1014 06. Baird JR, Sivasankar R, Hayward R, Wilson DR: Popliteal aneurysms: a review and analysis of 61 cases. Surgery 1966;59: 911–917 07. Varga ZA, Locke-Edmunds JC, Baird RN and the Joint Vascular Research Group, United Kingdom: A multicenter study of popliteal aneurysms. J Vasc Surg 1994;20:171–177 08. Witehouse WM Jr, Wakefield TW, Graham LM, Kazmers A, Zelenock GB, Cronenwett JL, Dent TL, Lindenauer SM, Stanley JC: Limb – threatening potential of arteriosclerotic popliteal artery aneurysms. Surgery 1983;93:694–699 09. Scwarz W, Berkowitz H, Taorimina V, Gatti J: The preoperative use of intraarterial trombolysis for a trombosed popliteal aneurysm: J Cardiovasc Surg 1984;25:465–468 10. Johnston KW, Rutherford RB, Tilson MD, Shah DM, Hollier L, Stanley JC: Suggested standards for reporting on arterial aneurysms. J Vasc Surg 1991;13:444–450 11. Dent TL, Lindenauer SM, Ernst CB, Fry WJ, Arbor Ann: Multiple arteriosclerotic arterial aneurysms. Arch Surg 1972;105: 338–344 12. Dawson I, Sie RB, van Bockel JH: Atherosclerotic popliteal aneurysms. Br J Surg 1997;84:293–299 13. Gounty P, Bertrand P, Duedal V, Cheynel-Hocquet C, Lanelin C, Escourolle F, Nussaumeand O, Vayssairat M: Limb salvage and popliteal aneurysms: advantages of preventive surgery. Eur J Vasc Endovasc Surg. 2000;19:496–500 14. Anton GE, Hertzer NR, Beven EG, O’Hara PJ, Krajewsky LP: Surgical management of popliteal aneurysms: trends in presentation, treatment, and results from 1952 to 1984. J Vasc Surg 1986;4:498–502 15. Wychulis AR, Spittell JA Jr, Wallace RB: Popliteal aneurysms. Surgery 1970;68:942–952 16. Gifford RW, Hines EA, Janes JM: An analysis and follow–up study of 100 popliteal aneurysms. Surgery 1953;33:284–293 17. Aune S, Trippestad A: Relative mortality of patients operated for femoro-popliteal occlusive disease. Eur J Vasc Surg 1994; 8:188–192. 18. Bowyer RC, Cawthorn SJ, Walker WJ, Giddings AEB: Conservative management of asymptomatic popliteal aneurysms. Br J Surg 1990;77:1132–1135 19. Dorigo W, Pulli R, Turini F, Pratesi G, Credi G, Alessi Innocenti A, Pratesi C: Acute leg ischaemia from thrombosed popliteal artery aneurysms: role of preoperative thrombolysis. Eur J Vasc Endovasc Surg 23:251–254
Received: April 7, 2004 Accepted: December 19, 2003
