Postoperative Incision Hernia in Patients with Abdominal Aortic Aneurysm and Aortoiliac Occlusive Disease: A Systematic Review

Current Endovascular Management of Abdominal Aortic Aneurysm

Fatal rupture of abdominal aortic aneurysm (AAA) remains a feared complication. Development of vascular surgery techniques over 50 years ago has fulfilled the promise of preventing rupture, but the significant morbidity associated with open repair causes physicians and their older patients pause. With the advent of less invasive endovascular techniques and devices, patients now have another viable treatment option. We review some of the important trials as well as discuss developments in the continually evolving field of endovascular repair of AAAs.

Assessment of insertion/deletion polymorphism of the angiotensin-converting enzyme gene in abdominal aortic aneurysm and inguinal hernia

The aim of the paper is to determine whether the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism is associated with abdominal aortic aneurysm (AAA) and inguinal hernia. A case-control study was conducted in 264 subjects: 65 patients with AAA, 91 patients with inguinal hernia, 19 patients with both AAA and hernia, and 89 controls were investigated for the ACE I/D polymorphism. Genotype analysis was performed using a polymerase chain reaction technique. Significant differences in the genotype between the patient groups and controls were identified (aneurysm versus control, P = 0.011; aneurysm plus hernia versus control, P = 0.022; hernia versus control, P = 0.001), whereas no differences were found within patient groups. Patients with AAA and/ or hernia had an increased prevalence of I/D heterozygosity, which persisted even after adjusting for differences in confounding clinical variables (aneurysm versus control, OR 0.3, 95% CI 0.2–0.8, P = 0.005; aneurysm plus hernia versus control, OR 0.3, 95% CI 0.1-0.9, P = 0.040; hernia versus control, OR 0.4, 95% CI 0.2–0.7, P = 0.004). In conclusion, an association between the heterozygote ACE I/D state and the presence of AAA and/or hernia was identified. The role of the ACE I/D polymorphism in aneurysm and hernia needs further investigation.

Abdominal aortic aneurysm and abdominal wall hernia as manifestations of a connective tissue disorder

BACKGROUND

Abdominal aortic aneurysms (AAAs) and abdominal wall hernias represent chronic degenerative conditions. Both aortic aneurysms and inguinal hernias share common epidemiologic features, and several investigators have found an increased propensity for hernia development in patients treated for aortic aneurysms. Chronic inflammation and dysregulation in connective tissue metabolism constitute underlying biological processes, whereas genetic influences appear to be independently associated with both disease states. A literature review was conducted to identify all published evidence correlating aneurysms and hernias to a common pathology.

METHODS

PubMed/Medline was searched for studies investigating the clinical, biochemical, and genetic associations of AAAs and abdominal wall hernias. The literature was searched using the MeSH terms "aortic aneurysm, abdominal," "hernia, inguinal," "hernia, ventral," "collagen," "connective tissue," "matrix metalloproteinases," and "genetics" in all possible combinations. An evaluation, analysis, and critical overview of current clinical data and pathogenic mechanisms suggesting an association between aneurysms and hernias were undertaken.

RESULTS

Ample evidence lending support to the clinical correlation between AAAs and abdominal wall hernias exists. Pooled analysis demonstrated that patients undergoing aortic aneurysm repair through a midline abdominal incision have a 2.9-fold increased risk of developing a postoperative incisional hernia compared with patients treated for aortoiliac occlusive disease (odds ratio, 2.86; 95% confidence interval, 1.97-4.16; P < .00001), whereas the risk of inguinal hernia was 2.3 (odds ratio, 2.30; 95% confidence interval, 1.52-3.48; P < .0001). Emerging evidence has identified inguinal hernia as an independent risk factor for aneurysm development. Although mechanisms of extracellular matrix remodeling and the imbalance between connective tissue degrading enzymes and their inhibitors instigating inflammatory responses have separately been described for both disease states, comparative studies investigating these biological processes in aneurysm and hernia populations are scarce. A genetic predisposition has been documented in familial and observational segregation studies; however, the pertinent literature lacks sufficient supporting evidence for a common genetic basis for aneurysm and hernia.

CONCLUSIONS

Insufficient data are currently available to support a systemic connective tissue defect affecting the structural integrity of the aortic and abdominal wall. Future investigations may elucidate obscure aspects of aneurysm and hernia pathophysiology and create novel targets for pharmaceutical and gene strategies for disease prevention and treatment.

Prevalence of Abdominal Wall Hernia in Participants With Abdominal Aortic Aneurysm Versus Peripheral Arterial Disease—A Population-Based Study

Small studies suggest an association between abdominal aortic aneurysms (AAAs) and hernias, possibly related to connective tissue weakness. We evaluated the association between AAA and abdominal wall hernia (AWH), using peripheral arterial disease (PAD) patients as controls, in Olmsted County, Minnesota. In a retrospective cohort study we queried the electronic medical records for the diagnosis of AAA. The resulting data were then queried for prevalence of AWH. The same set of queries was repeated for PAD. Occurrence of AWH in the 2 groups was compared using the chi-square test. Of the 187 151 patient records queried, 939 had AAA and 3465 had PAD. Abdominal wall hernia occurred in 157 (16.7%) patients with AAA and in 343 (9.9%) patients with PAD. Abdominal wall hernia was 1.7 times more prevalent in those with AAA versus PAD ( P < .0001). A history of hernia may prompt screening for AAA in some patients.

Increased prevalence of abdominal aortic aneurysm in patients undergoing inguinal hernia repair compared with patients without hernia receiving aneurysm screening

BACKGROUND

The introduction of screening programs for abdominal aortic aneurysm (AAA) is being contemplated by health services in several countries. The correlation between aortic aneurysm and abdominal wall hernias is well reported, and inguinal hernia has been identified as a risk factor for aortic aneurysm. However, the prevalence of AAA in patients with inguinal hernia has not been adequately documented. This study evaluated whether patients with inguinal hernia are at increased risk of having an AAA compared with patients without hernia receiving aneurysm screening.

METHODS

Men aged >55 undergoing primary inguinal hernia repair underwent ultrasound imaging of the abdominal aorta to screen for aneurysm. A reference group was selected from men without clinical evidence of inguinal hernia participating in an AAA screening program. Prevalence and odds ratios of AAA in the two groups were calculated.

RESULTS

The study cohort comprised 235 patients with inguinal hernia and 203 controls. The mean ± SD aortic diameter was 22 ± 9 mm in patients with inguinal hernia vs 20 ± 6 mm for controls (P = .045). The prevalence of AAA was 8.1% in the hernia group and 3.9% in the control group (adjusted odds ratio, 3.9; 95% confidence interval, 1.6-9.5; P = .039). For aneurysms >4 cm, the prevalence was 5.1% in those with an inguinal hernia and 1.5% in those without an inguinal hernia (adjusted odds ratio, 4.7; 95% confidence interval, 1.2-18.5, P = .025).

CONCLUSIONS

Inguinal hernia was a significant risk factor for AAA. Entry into a screening program of men aged >55 admitted for inguinal hernia repair should be considered.

Genes and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a multifactorial disease with a strong genetic component. Since the first candidate gene studies were published 20 years ago, approximately 100 genetic association studies using single nucleotide polymorphisms (SNPs) in biologically relevant genes have been reported on AAA. These studies investigated SNPs in genes of the extracellular matrix, the cardiovascular system, the immune system, and signaling pathways. Very few studies were large enough to draw firm conclusions and very few results could be replicated in another sample set. The more recent unbiased approaches are family-based DNA linkage studies and genome-wide genetic association studies, which have the potential of identifying the genetic basis for AAA, only when appropriately powered and well-characterized large AAA cohorts are used. SNPs associated with AAA have already been identified in these large multicenter studies. One significant association was of a variant in a gene called contactin-3, which is located on chromosome 3p12.3. However, two follow-up studies could not replicate this association. Two other SNPs, which are located on chromosome 9p21 and 9q33, were replicated in other samples. The two genes with the strongest supporting evidence of contribution to the genetic risk for AAA are the CDKN2BAS gene, also known as ANRIL, which encodes an antisense ribonucleic acid that regulates expression of the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, and DAB2IP, which encodes an inhibitor of cell growth and survival. Functional studies are now needed to establish the mechanisms by which these genes contribute toward AAA pathogenesis.

An assessment of between-recti distance and divarication in patients with and without abdominal aortic aneurysm

INTRODUCTION

The study assessed whether there is a greater incidence of divarication of the recti and whether between-recti distance is greater in patients with abdominal aortic aneurysm (AAA).

PATIENTS AND METHODS

The study consisted of two parts: a radiological and a clinical assessment. All patients with a confirmed AAA on computerised tomography were included and compared with patients in whom AAA was excluded with imaging. Between-recti distance was measured using a computerised image viewer and clinical divarication was assessed by a surgical registrar or consultant.

RESULTS

In the radiological part of the study, 108 patients with AAA were compared with 84 with colorectal cancer. Median between-recti distance was 38 mm (range, 25-59 mm) in the AAA group and 27 mm (range, 20-44.5 mm) in the non-AAA group (P=0.006). AAA diameter did not correlate with between-recti distance. The clinical study included 50 patients (25 AAA). The groups were well matched, with only a greater incidence of diabetes in the AAA group (20% vs 0%; P=0.018). AAA patients were more likely to have clinically detected divarication of the recti (76% vs 36%; P=0.004).

CONCLUSIONS

Patients with AAA have greater radiological and clinical evidence of divarication. It is suggested that patients with divarication be screened for AAA.

Randomized clinical trial of mesh versus sutured wound closure after open abdominal aortic aneurysm surgery

Background

Incisional herniation is a common complication of abdominal aortic aneurysm (AAA) repair. This study investigated whether prophylactic mesh placement could reduce the rate of postoperative incisional hernia after open repair of AAA.

Methods

This randomized clinical trial was undertaken in three hospitals. Patients undergoing elective open AAA repair were randomized to routine abdominal mass closure after AAA repair or to prophylactic placement of polypropylene mesh in the preperitoneal plane.

Results

Eighty-five patients with a mean age of 73 (range 59–89) years were recruited, 77 (91 per cent) of whom were men. There were five perioperative deaths (6 per cent), two in the control group and three in the mesh group (P = 0·663), none related to the mesh. Sixteen patients in the control group and five in the mesh group developed a postoperative incisional hernia (hazard ratio 4·10, 95 per cent confidence interval 1·72 to 9·82; P = 0·002). Hernias developed between 170 and 585 days after surgery in the control group, and between 336 and 1122 days in the mesh group. Four patients in the control group and one in the mesh group underwent incisional hernia repair (P = 0·375). No mesh became infected, but one was subsequently removed owing to seroma formation during laparotomy for small bowel obstruction.

Conclusion

Mesh placement significantly reduced the rate of postoperative incisional hernia after open AAA repair without increasing the rate of complications. Registration number: ISRCTN28485581 (http://www.controlled-trials.com).

Diastasis Recti and Abdominal Aortic Aneurysm

An association between abdominal aortic aneurysm (AAA) and abdominal wall hernia has been suggested, possibly reflecting a common collagen disorder. The same mechanism may also cause a greater frequency of diastasis recti among patients at risk of developing AAA. Diastasis recti could be used to identify patients at risk of AAA, with implications for AAA screening. The aim of this study was to determine whether an association between diastasis recti and AAA could be demonstrated.

The preoperative computed tomographic (CT) scans of 75 male patients undergoing elective AAA repair were retrospectively examined and linea alba width recorded at supraumbilical and subumbilical levels. Measurements were compared with controls frequency matched for age.

Fifty patients with AAA were observed to have supraumbilical diastasis recti on preoperative CT compared with 47 controls. Mean linea alba width was not significantly different between the two groups at either the supraumbilical (19.3 mm vs 20.7 mm, p = .45) or subumbilical (3.6 mm vs 4.3 mm, p = .43) level.

The findings do not support the hypothesis that the presence of diastasis recti can serve as an indication to select male patients for screening for AAA.

Prevalence of abdominal aortic aneurysms in over 65-year-old men with inguinal hernias

INTRODUCTION

The aim of this study was to determine the prevalence of abdominal aortic aneurysms (AAAs) in over 65-year-old men who have inguinal hernias and discuss if pre-operative selective screening of this population is appropriate.

PATIENTS AND METHODS

A prospective study on 70 consecutive male patients with an age range of 65-88 years (mean, 74 years) who were referred to a single vascular consultant's out-patient clinic with an inguinal hernia were screened for the presence of an AAA with an ultrasound scan before hernia repair over a period of 3 years.

RESULTS

Two patients were found to have an AAA measuring 3.8 cm and 6.0 cm giving an AAA prevalence of 3% (exact 95% confidence interval = 0-10%).

CONCLUSIONS

This study does not demonstrate an increased AAA prevalence in over 65-year-old male patients with inguinal hernias, scanned pre-operatively when compared to screening programmes. Selective screening of this cohort cannot be justified on this evidence.

Comparison of ultrasonography with computed tomography in the diagnosis of incisional hernias

BACKGROUND

The objective of this study is to determine the reliability and validity of ultrasonography (US) in diagnosing incisional hernias in comparison with computed tomography (CT). The CT scans were assessed by two radiologists in order to estimate the inter-observer variation and twice by one radiologist to estimate the intra-observer variation. Patients were evaluated after reconstruction for an abdominal aortic aneurysm or an aortoiliac occlusion.

METHODS

Patients with a midline incision after undergoing reconstruction of an abdominal aortic aneurysm or aortoiliac occlusion were examined by CT scanning and US. Two radiologists evaluated the CT scans independently. One radiologist examined the CT scans twice. Discrepancies between the CT observations were resolved in a common evaluation session between the two radiologists.

RESULTS

After a mean follow-up of 3.4 years, 40 patients were imaged after a reconstructed abdominal aortic aneurysm (80% of the patients) or aortoiliac occlusion. The prevalence of incisional hernias was 24/40 = 60.0% with CT scanning as the diagnostic modality and 17/40 = 42.5% with US. The measure of agreement between CT scanning and US expressed as a Kappa statistic was 0.66 (95% confidence interval [CI] 0.45-0.88). The sensitivity of US examination when using CT as a comparison was 70.8%, the specificity was 100%, the predictive value of a positive US was 100%, and the predictive value of a negative US was 69.6%. The likelihood ratio of a positive US was infinite and that of a negative US was 0.29. The inter- and intra-observer Kappa statistics were 0.74 (CI 0.54-0.95) and 0.80 (CI 0.62-0.99), respectively.

CONCLUSIONS

US imaging has a moderate sensitivity and negative predictive value, and a very good specificity and positive predictive value. Consistency of diagnosis, as determined by calculating the inter- and intra-observer Kappa statistics, was good. The incidence of incisional hernias is high after aortic reconstructions.

Long-term wound advantages of the laparoscopic approach in rectal cancer

BACKGROUND

No long-term advantage of the laparoscopic approach has been demonstrated in colorectal surgery. This study compared the risk of incisional hernia between laparoscopic and open surgery for rectal cancer.

METHODS

Between 1994 and 2004, patients who had restorative mesorectal excision for rectal cancer by laparoscopy were compared with those treated by open surgery. Follow-up was prospective, and incisional hernia was considered to be any abdominal wound dehiscence occurring at the midline, extraction, trocar or ileostomy site. Cumulative risks of hernia were evaluated by the Kaplan-Meier method and compared with the log rank test.

RESULTS

Some 155 patients had a laparoscopic and 165 an open procedure. The two groups were similar in terms of age, sex, body mass index, tumour stage, loop ileostomy and morbidity. The conversion rate was 20.6 per cent. The rate of incisional hernia in all patients was 11.4 per cent at 1 year, 21.1 per cent at 2 years and 23.7 per cent at 5 years. The rate of hernia at 5 years was significantly lower in the laparoscopic than in the open group (13.0 versus 33.0 per cent; P < 0.001). The rate of hernia due specifically to the laparoscopic procedure (extraction and trocar sites) was ten times less than that after a primary or secondary open procedure (2.1 versus 16.1-33.1 per cent; P < 0.001).

CONCLUSION

The laparoscopic approach decreases the risk of long-term incisional hernia following restorative mesorectal excision for rectal cancer. The benefit is most apparent in patients without conversion or postoperative complication.

Abdominal aortic aneurysm and diastasis recti

Midline abdominal incisional hernias are common following open repair of abdominal aortic aneurysms. These may be caused by the weakness of connective tissue. This study sought to determine the prevalence of diastasis recti among unoperated Caucasian males with abdominal aortic aneurysm compared to a control group with atherosclerotic lower extremity peripheral arterial disease. Forty-two consecutive white males referred for evaluation of abdominal aortic aneurysm (n = 18) or peripheral arterial disease (n = 24) were examined by a single examiner at the Mayo Clinic. Both groups were similar in terms of age and smoking history, 2 major risk factors for both abdominal aortic aneurysm and peripheral arterial disease. Abdominal aortic aneurysm patients ranged in age from 59 to 89 (mean, 73.2) years. Seventeen of 18 (94.4%) had a history of smoking. Peripheral arterial disease patients ranged in age from 52 to 93 (mean, 70.8) years. Twenty-one of 24 (87.5%) had a history of smoking. Diastasis recti were present in 12 of 18 (66.7%) subjects with abdominal aortic aneurysm versus 4 of 24 (16.7%) subjects with peripheral arterial disease (P = .001, 2-tailed Fisher exact test). Diastasis recti are significantly more common in males with abdominal aortic aneurysm than peripheral arterial disease and may provide an important clue to screen for abdominal aortic aneurysm in those at risk.

Late results of mesh wound closure after elective open aortic aneurysm repair

INTRODUCTION

Incisional hernia is a common late complication after abdominal aortic aneurysm (AAA) repair. We examined the outcome after prophylactic placement of a pre-peritoneal polypropylene mesh during abdominal closure in consecutive patients having elective AAA repair.

REPORT

At least 30 months after surgery, 28 patients underwent clinical and ultrasound examination of their surgical wound for incisional hernias. Only one patient had a hernia in the original surgical scar. No patients had late mesh-related wound problems.

DISCUSSION

Pre-peritoneal polypropylene mesh placement is a simple, safe and effective method to decrease the incidence of incisional hernia after AAA repair.