Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 6  |  Issue : 3  |  Page : 171-175

Clinical profile of abdominal aortic aneurysms undergoing open surgical repair: A single-center experience


Department of Cardiovascular and Thoracic Surgery, Division of Vascular Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India

Date of Web Publication29-Aug-2019

Correspondence Address:
Dr. Sreekumar Ramachandran
Department of Cardiovascular and Thoracic Surgery, Division of Vascular Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijves.ijves_96_18

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  Abstract 


Introduction: An abdominal aortic aneurysm (AAA) is defined as an aortic diameter at 1.5 times the normal diameter at the level of the renal arteries, which is approximately 2 cm. Existing data of clinical profile of AAA are mainly based on screening studies in the Western population. Materials and Methods: This is a retrospective observational study which included 165 patients who underwent conventional open repair for elective AAAs in a single center from January 2008 to August 2016. Results: The mean age of the patient cohort was 64.9 years with majority (92.7%) of them being a male cohort (male: female, 12.75:1). The mean size of the aneurysm was 6.8 cm. Ninety-six percent of the patients were hypertensive, 86% were smokers, 4.2% of patients had chronic obstructive pulmonary disease, and 16% of patients had preoperative renal dysfunction. Fifty-four percent of the patients had significant coronary artery disease (CAD), of which 19% underwent coronary intervention. Eighty-two percent of patients had infrarenal and 18% had juxtarenal AAA. Thirty-three percent of the patients who underwent open repair had concomitant common iliac artery aneurysm/ectasia. Conclusion: Clinical profile of AAA in this study shows a significantly high preponderance for males, hypertensive patients, and smokers, which have already been established as significant risk factors. Moreover, majority of the patients had significant CAD detected by routine preoperative cardiac evaluation which shows the significant coexistence between AAA and CAD in our population. Apart from coronary angiogram, evaluating patients with dobutamine stress echocardiography for inducible ischemia will act as a guide to detecting patients who are likely to benefit from revascularization and who are at increased risk of periprocedural cardiac events.

Keywords: Abdominal aortic aneurysm, clinical profile, open surgical repair


How to cite this article:
Afshan P T, Pitchai S, Ramachandran S, Goura P, Ramachandran H. Clinical profile of abdominal aortic aneurysms undergoing open surgical repair: A single-center experience. Indian J Vasc Endovasc Surg 2019;6:171-5

How to cite this URL:
Afshan P T, Pitchai S, Ramachandran S, Goura P, Ramachandran H. Clinical profile of abdominal aortic aneurysms undergoing open surgical repair: A single-center experience. Indian J Vasc Endovasc Surg [serial online] 2019 [cited 2019 Dec 11];6:171-5. Available from: http://www.indjvascsurg.org/text.asp?2019/6/3/171/265787




  Introduction Top


There has been a transition in the clinical profile of abdominal aortic aneurysms (AAAs) in various parts of the world. Aneurysms secondary to syphilitic infection were prevalent at the time when the disease was common, in the late 14th century.[1] Most of the epidemiological data regarding AAA have been obtained from screening studies conducted in the primarily Caucasian population. The clinical profile in Asian population and India has not been studied by systematic screening methods targeting the high-risk population. We studied the clinical profile of those patients who have undergone open surgical repair (OSR) of AAA in our center.

Aim of the study

The aim was to study the clinical profile and demographic parameters and risk factors of patients undergoing elective open repair of AAAs.


  Materials and Methods Top


This was a retrospective observational study in an urban quaternary care center. Over a period of 8 years from January 2008 to August 2016, 165 patients who underwent conventional open repair for elective AAAs were included in the retrospective analysis. The demographic parameters and the risk factors for the development of AAAs in this group of patients were studied. This cohort included the patients presenting with symptomatic or asymptomatic infrarenal abdominal and juxtarenal AAAs (JRAAAs), all presenting in the elective setting. Suprarenal, Type 4 thoraco-AAAs, ruptured AAAs, and isolated iliac artery aneurysms were excluded from the study. Approval was obtained from the Technical Advisory Committee and the Institutional Ethics Committee for the conduct of the study.


  Results Top


During the period of 8 years from 2008 to 2016, 165 patients underwent elective OSR of AAAs. Demographic and clinical details of the patients are given in [Table 1]. Patients were followed up until May 31, 2017 (mean follow-up, 39.7 months; median, 34.9 months; range, 6–110.6 months).
Table 1: Demographic details and risk factors of patients undergoing open repair of abdominal aortic aneurysm (n=165)

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The mean size of the aneurysm was 6.8 cm (range, 4–14 cm; standard deviation = 1.7). Of the 165 patients, 25 were electively operated for aneurysms below the threshold size for intervention. The reasons to electively operate on such small-sized aneurysms were when the aneurysms became symptomatic or when there was a rapid expansion of aneurysm (at >1 cm/year) and when the aneurysms were of inflammatory nature.

Smoking history

This group was divided into three categories based on the current smoking habits. Active smokers were defined as patients who have been smoking until the past 6 weeks. Reformed smokers were defined as patients who stopped smoking at least 6 weeks before the date of surgery, and nonsmokers were the patients who have never smoked. The distribution of smoking in the study cohort is shown in [Figure 1].
Figure 1: Pie chart showing distribution of smoking in the cohort

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Preoperative coronary status

All patients with elective AAAs undergo coronary imaging by computed tomography (CT) coronary angiogram (CAG) or catheter CAG as an institutional protocol. Most of the patients underwent conventional catheter CAG with only a few patients undergoing CT CAG. The CAG findings were divided into five groups for stratification: normal CAG, mild/minor disease (minor plaques and stenosis <50%), single-vessel disease >50%, double-vessel disease (DVD), and triple-vessel disease (TVD). The incidence of each group in the cohort is given in [Table 2]. Only those patients with single-vessel disease >50% (involving left main (LM) stem or left anterior descending [LAD] artery) or DVD/TVD, on CAG, were considered to have significant coronary artery disease (CAD).
Table 2: Coronary status of patients undergoing open repair of abdominal aortic aneurysm (n=165)

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Significant CAD was seen in 89 patients (53.9%). Of this group, 32 patients (19.4%) underwent coronary intervention, either percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG), before surgery. In those patients who had undergone coronary intervention in the form of PCI with drug-eluting stent, surgery was done 3 months after PCI, while the patient was still on aspirin and after stopping clopidogrel for at least 5 days prior to surgery. In such patients, cardiology clearance was obtained and surgery was done after counseling the patients about the increased risk of periprocedural myocardial infarction (MI) due to the risk of stent thrombosis caused by stopping clopidogrel. In those patients who had undergone CABG, surgery for AAA was done later with single antiplatelet (aspirin) cover alone, once the patient recovered from CABG, after 1–2 months.

Five patients in the study group had MI in the postoperative period. Of those cases, one patient had mild CAD, and other patient had normal coronaries. Two patients had single-vessel disease >50%, and one patient had TVD. All patients with significant CAD had undergone preoperative coronary intervention. There was one mortality among those patients who had perioperative MI. He had undergone PCI preoperatively, for single-vessel disease >50%.

Type of aneurysm

JRAAA was present in 29 patients (17.6%), and the remaining patients (136%–82.4%) had infrarenal AAA (IRAAA).

Common iliac artery aneurysms associated with abdominal aortic aneurysm

Fifty-four (33.1%) of the cohort had common iliac artery (CIA) aneurysms requiring repair during the primary surgical intervention.


  Discussion Top


An AAA is defined as an aortic diameter at least 1.5 times the normal diameter at the level of the renal arteries, which is approximately 2 cm. Thus, generally, a segment of the abdominal aorta with a diameter of >3.0 cm is considered an aortic aneurysm.[2]

Approximately 80% of aortic aneurysms occur between the renal arteries and the aortic bifurcation.[3]

Risk factors

Age, sex, ethnicity, and smoking are among some of the risk factors associated with AAA.

The risk of AAAs increases dramatically after 60 years of age. Clinically relevant aneurysms (> 4 cm in diameter) are present in approximately 1% of men between 55 and 64 years of age, and for each decade thereafter, the prevalence increases by 2%–4%.[4],[5] In one study, AAAs were found to occur more frequently in caucasian population.[6]

In our study, the mean age of the study group was 65 years. As the study involves only those patients who have undergone elective open repair of AAA, only those patients who meet the threshold size for surgical intervention or are symptomatic have been studied. As there are no screening programs for AAA targeting the high-risk population in India, it is likely that if a screening program is implemented, it will give information regarding the incidence and prevalence of the condition, and it would lead onto enabling diagnosis of the condition at a lower age, when the affected people are asymptomatic.

There is a significant male preponderance seen in the study group – 12.7 times. Existing data suggest that AAA is 4–6 times more common in men than in women.[6],[7] The significantly higher male preponderance in this study may be due to the other risk factors that have a significantly high prevalence among the men in India – such as smoking; compared to females. Although data suggest that female smoking is growing at a faster rate than smoking among males, in India,[8] other social factors leading to greater female autonomy have been linked to increased smoking among women, in Western countries. Furthermore, other factors such as reluctance for lifestyle modification for addressing the risk factors and poor compliance with medications among men may lead to more men-satisfying criteria for surgical intervention. In addition, AAAs develop in women approximately 10 years later than in men.[9]

Hypertension has also been found to be a major risk factor associated with AAA. In our study, 96% of the patients were found to be hypertensive on diagnosis, which reinstates the fact that poorly controlled blood pressure leads onto expansion of the aneurysm and further complications, such as rupture.

Several studies have pointed diabetes mellitus (DM) to be a negative risk factor associated with AAA.[10] In our study group, the prevalence of diabetes was only 11%, which is much lower than the prevalence of DM in similar age group individuals in India. The advanced glycation associated with diabetes will induce cross-linking of collagen lattices in the aortic media, and this cross-linking resists proteolysis and inhibits secretion of the matrix metalloproteinases thought to mediate AAA formation.[11] Diabetes also suppresses plasmin, which is an activator of matrix metalloproteinases.[12] These effects decrease aortic wall degradation directly and may also explain the thicker abdominal aortic wall observed in diabetes. As per the law of Laplace, a thicker aortic wall reduces wall stress,[13] and wall stress is considered fundamental to AAA development and progression.[14]

Patients with chronic kidney disease (CKD), particularly those on renal replacement therapy, are at high risk for developing AAA.[15] The prevalence of renal dysfunction in our study group was 16.4%. It is important to consider the degree of preoperative renal dysfunction, as postoperative acute renal failure is a common complication of AAA surgery and preoperative renal dysfunction is a major risk factor for the same. On the other hand, many AAA patients who do not undergo surgery have chronic renal failure. Atherosclerosis and oppression of the renal artery or renal ischemia due to arterial stenosis might be related to the incidence of CKD in AAA patient.[16] Cohen et al. in a review of 251 patients with preoperative renal failure suggested that patients with mild renal dysfunction (creatinine level, 2–4 mg/dl) can undergo AAA repair without added morbidity or mortality. In addition, patients on chronic hemodialysis can undergo surgical repair of AAAs with the expectation of a low perioperative complication rate if they are dialyzed the day before operation. Patients with severe renal dysfunction (serum creatinine >4 mg/dl) who are not on hemodialysis should be considered for dialysis preoperatively in an attempt to reduce the high incidence of serious postoperative renal functional deterioration and subsequent morbidity.[17]

The frequency of AAA in male chronic obstructive pulmonary disease (COPD) patients aged 65 years is considerably higher and increased further still in those individuals with additional comorbidities/risk factors.[18] In the study group, 4.2% of patients were diagnosed to have COPD preoperatively. Although there has been an improvement in the safety and outcomes of patients with COPD undergoing AAA repair, the overall mortality remains higher than that in patients without COPD. In addition, there are high mortality rates among patients with COPD who did not undergo operation. Increased pulmonary complications and diminished long-term survival are seen in O2-dependent COPD patients undergoing AAA repair. This must be carefully factored into the risk–benefit analysis before recommending elective AAA repair in these patients.[19]

A significant proportion of patients was smokers – 86.7%, and majority of them were reformed smokers. Smoking has been found to be a major risk factor for aneurysm formation and rupture.[5],[6] One study[5] estimated that continued smoking increases the rate of aneurysm growth by 20%–25%. Therefore, smoking cessation should be advocated to all individuals with AAA or a positive family history of AAA and offered cessation interventions.

Smoking is a very strong risk factor for the presence of an AAA in both men and women, with odds ratios ranging from 3 to 12.[6],[20] In the large (n = 114567) Aneurysm Detection and Management screening study, a history of ever smoking was associated with an odds ratio of 2.97 (95% confidence interval [CI], 2.65–3.32) for 3–3.9-cm AAAs and 5.07 (95% CI, 4.13–6.21) for ≥4-cm AAAs.[6] Smoking was considered to be responsible for 75% of the excess prevalence of AAAs ≥4 cm. Franks et al. have shown that in smokers, the risk of developing an AAA increases with increasing mean arterial and diastolic blood pressure and two aspects of current smoking habit: the number of cigarettes currently smoked and the depth of inhalation.[21]

In this study, most of the patients were reformed smokers as they had stopped smoking following medical advice when AAA was diagnosed or when they were diagnosed to have other comorbid conditions such as CAD and peripheral vascular disease.

It is currently accepted that revascularization by PCI or CABG should be performed when a stenosis >50% is observed during angiography of the LM stem or proximal LAD coronary artery; the patient has a single remaining patent vessel or suffers from DVD or TVD with a left ventricular ejection fraction <40%.[22] Another indication for revascularization resulted from the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation trial: any coronary stenosis >50% that can produce myocardial ischemia in >10% of the left ventricular myocardium.[22],[23]

Fifty-four percent of the patients were diagnosed to have CAD on preoperative cardiac evaluation as per institution protocol, by CAG. Of this group, 32 patients (19.4%) underwent some form of coronary intervention, either PCI or CABG before surgery. As the risk associated with OSR of AAA is quite high in this highrisk population with co-existing significant CAD and AAA, routine screening for AAA in CAD patients and vice versa is to be suggested. When there is significant CAD, whether it requires intervention before or after AAA repair is decided by taking into account the characteristics of the aneurysm, and the extent and severity of CAD. CABG can be combined with open repair of AAA, and its feasibility and implications on expense on patient care have been studied recently.[24],[25] Combined approach is to be suggested when adequate facilities are available in appropriate patients who are likely to tolerate the procedure.

Five patients in the study group had MI in the postoperative period. Of those patients, one had mild CAD and one had normal coronaries. The remaining three patients had significant CAD, of which two patients had singlevessel disease >50% and one patient had TVD. These three patients who had significant CAD had undergone preoperative coronary intervention. There was one early mortality, among those patients who had perioperative MI. He had undergone PCI preoperatively, for single-vessel disease >50%. These data show the inadequacy of using CAG as a tool for evaluating the risk for perioperative cardiac events associated with major surgeries.

The stress associated with major surgery such as AAA repair itself will render the patient to increased risk of perioperative cardiac events. As CAG evaluates the cardiac disease status only at resting state, we suggest evaluating patients for inducible ischemia with dobutamine stress echocardiography, especially in those patients with risk factors for CAD. It will act as an adjunct to CAG, in detecting those patients with increased risk of periprocedural cardiac events.

Whether prophylactic coronary revascularization with PCI or CABG surgery is beneficial in patients with AAA scheduled for open repair surgery is controversial. There have been studies that suggest coronary intervention for all significant CAD patients, prior to AAA repair or selective intervention only based on whether inducible ischemia is present or not. Based on the findings of our study, we suggest selective intervention in patients with significant CAD, based on the findings of inducible ischemia or based on other high-risk factors.

A review of patients with iliac aneurysms in 1994 revealed that only 11% presented without a concomitant aortic aneurysm.[26] The involvement of adjacent arterial segments is not uncommon in IRAAAs, with 10%–25% involving the iliac arteries.[27] Iliac artery aneurysms occur most frequently in the CIA (70%), typically in conjunction with an AAA. Isolated aneurysms of the CIA are relatively infrequent (6.4% of patients).[28] In our study, the incidence of CIA aneurysm/ectasia in conjunction with AAA was 33%. The slightly higher incidence than CIA aneurysms with AAA described in literature may be due to the fact that even ectatic CIA that was repaired with AAA was included in the same group with CIA aneurysms, in this study.


  Conclusion Top


Clinical profile of AAA in this study shows a significantly high preponderance for males, hypertensive patients, and smokers, which have already been established as significant risk factors. Moreover, majority of the patients had significant CAD detected by routine preoperative cardiac evaluation which shows the significant coexistence between AAA and CAD in our population. Apart from CAG, evaluating patients with dobutamine stress echocardiography for inducible ischemia will act as a guide to detecting patients who are likely to benefit from revascularization and who are at increased risk of periprocedural cardiac events.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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