CASE REPORT
Year : 2012 | Volume
: 11 | Issue : 3 | Page : 176--181
Abdominal aortic aneurysm and the challenges of management in a developing country: A review of three cases
Augustine Z Sule1, Bill Ardil2, Emmanuel O Ojo1,
1 Department of Surgery, Jos University Teaching Hospital, Jos, Nigeria
2 Department of Surgery, ECWA Hospital, Jos, Plateau State, Nigeria
Correspondence Address:
Augustine Z Sule
P. O. Box 297, Jos, Plateau State
Nigeria
Abstract
There is an increase in the incidence of abdominal aortic aneurysm (AAA) over the last six decades, probably as a result of higher longevity and lifestyle changes witnessed in the years following World War II. Though earlier studies mainly from Southern Africa suggest abdominal aortic aneurysms as uncommon amongst black Africans, recent reports from Africa emphasized an increasing incidence of vascular diseases and its sequelae including AAA. There are, however, few documented case reports of AAA in our environment over the years suggesting the rarity of this disease. We report the management and outcome of three different types of infrarenal AAA with synthetic graft in a General Surgery Unit over a four-year period between 2001 and 2005. Follow-up evaluation confirmed a successful outcome in two patients. Abdominal aortic aneurysms may be occurring more frequently than reported in our environment and its management, using basic evaluation techniques, can be successfully achieved with reasonable outcome when performed in a non-specialized unit by General Surgeons in institutions with limited resources. Contrary to the popularly held view of rarity of AAA, the disease may be increasing in incidence amongst black African. Its evaluation and treatment is also feasible with the availability of reconstructive graft in a non-specialized surgical unit.
How to cite this article:
Sule AZ, Ardil B, Ojo EO. Abdominal aortic aneurysm and the challenges of management in a developing country: A review of three cases.Ann Afr Med 2012;11:176-181
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How to cite this URL:
Sule AZ, Ardil B, Ojo EO. Abdominal aortic aneurysm and the challenges of management in a developing country: A review of three cases. Ann Afr Med [serial online] 2012 [cited 2023 Jun 9 ];11:176-181
Available from: https://www.annalsafrmed.org/text.asp?2012/11/3/176/96881 |
Full Text
Introduction
Dilatation of localized segments of the arterial system are called aneurysms. [1] It occurs commonly in the abdominal aorta; 95% have associated atheromatous degeneration and 95% occur below the renal arteries. [2] The incidence of abdominal aortic aneurysm (AAA) has been increasing over the last 60 years, probably as a consequence of the smoking epidemics that developed in the years that followed the Second World War. [3] In the same period, there has been a radical change in the type of aortic aneurysm seen from those cause by infection and located in the thoracic aorta to the one in the abdominal aorta cause by atherosclerosis.
The pattern of AAA varies between countries depending on ethnic and geographic differences related to the burden of risk factors. [4] Reports, particularly those from Southern Africa, suggest that aortic aneurysms are common amongst Caucasian population, are rare amongst black Africans, occur in younger persons with equal sex distribution and are non-atherosclerotic. [5],[6] In these studies, there are conflicting reports on the regional distribution of aneurysm in the aorta amongst black African patients with some reporting non involvement of the thoracic aorta and others showing a high incidence of thoracic aortic aneurysm compared to those of the abdomen. The increasing involvement of etiologic factors such as infectious conditions, including human immunodeficiency disease (HIV) are speculated to account for the differences. [7] The natural history of an aneurysm is to dilate and rupture. Abdominal aortic aneurysm is, however, asymptomatic but a potentially fatal condition for which the proper treatment is elective surgery before rupturing occur. [8] The management of AAA is also, a challenging surgical undertaking when not performed in a specialized unit and by cardiovascular surgeons; and in the midst of limited resources required for such procedures.
We report our experience with three cases of infrarenal AAA repaired in a General Surgery Unit in a tertiary hospital in Nigeria between 2001 and 2005 highlighting a seemingly increasing prevalence of the disease and the problems of management in such a setting.
Case Reports
Case 1
Mr. I. Y. is a 60-year-old known diabetic and hypertensive who presented to us with a three and a half year history of central abdominal pain and two year history of an enlarging periumbilical swelling. The pain was constant and radiated to the back with occasional exacerbation. About a year and a half later, he noticed a progressively increasing mass in the periumbilical region. History of previous abdominal trauma or persistent cough and fever were absent. He had bilateral inguinal hernia repair 17 years earlier. He is a non-smoker and is not presently on any medication for the treatment of his premorbid disease.
Physical examination revealed a cheerful man who was afebrile. His blood pressure was 140/85mmHg and pulse rate was 80 beats per minute. He had a paraumbilical hernia and bilateral inguinal herniorraphy scars. A pulsatile poorly defined mass 16 × 12 cm was felt in the periumbilical region in the line of the aorta. We could palpate the upper margin of the mass. His breath sounds were vesicular and only the first and second heart sounds were heard. There were no peripheral pulse deficits. Other systems examined were essentially normal.
Abdominal ultrasound revealed an abdominal aortic aneurysm 13 × 15 cm involving the distal aorta. It had a thick anterior wall. The segment of the aorta lying behind the aneurysm sac appeared normal and feed the aneurysm through a hole in its anterior wall. The renal arteries were not involved. The left kidney was hydronephrotic. The electrolyte and urea, and fasting blood sugar (4.6mmol/l) were normal. The packed cell volume was 35% while the total white cell count was 9,400/mm 3 with a lymphocyte count of 50%. Plain abdominal X-rays revealed a soft tissue mass with no calcification.
He was prepared for and had exploratory laparotomy with continuous monitoring (blood pressure, pulse rate, temperature, respiratory rate, oxygen saturation and urine output. At exploration, a distal infrarenal saccular aortic aneurysm with a fibrous outer wall measuring 16 × 12 cm was found. The renal, inferior mesenteric and common iliac arteries were uninvolved. The aneurysm sac and the adjoining normal aorta and iliac arteries were exposed by incising the posterior abdominal wall peritoneum overlying the aneurysm. Ten thousand units of heparin was injected directly into the normal adjoining proximal aorta after the graft had been preclotted. Vascular clamps were then applied to the aorta and common iliac arteries just adjacent to the sac. A longitudinal incision was made in the fibrous wall of the sac. Beneath the fibrous wall was a middle layer of thrombus within which was contained whitish non-foul smelling liquid and an inner layer of yellowish thick thrombus. The sac communicated with the infrarenal aorta through a hole in its anterior wall about 1.5 × 2 cm in diameter. The margin of the hole appeared uninfected. Thrombus was evaluated and part sent for culture and sensitivity, and acid fast bacilli. The cavity was thoroughly cleaned and the hole in the aorta closed with a patch of prosthetic graft. The clamps were removed beginning with the distal one over the common iliac. The sac was reduced by trimming the edges and the residual sac sutured over the graft. The abdominal cavity was cleaned and closed. He had transfusion of two units of blood intraoperatively. The anticoagulant effect of heparin was reversed with intravenous protamine sulfate 50 mg.
Antibiotics were continued for four weeks. His kidney function dropped within the first 24 h with the blood urea rising to 19.4mmol/l (normal: 2.5 - 6.6mmol/l). He also had evidence of gastritis with coffee ground nasogastric tube effluent. Both complications were managed successfully. He was discharged 15 days after surgery. One year after the repair, the patient has remained well with a normal kidney function, aortic caliber on imaging study and a stable cardiac function. Culture of the non-foul smelling liquid within the thrombus yielded no growth.
Case 2
Miss S. M. is a 31-year-old civil servant who presented to the unit with a nine-month history of a painful progressive central abdominal swelling. The pain was constant in location and occasionally radiated to the back. She had no symptoms of peripheral vascular insufficiency or history of abdominal surgery and trauma. She does not smoke. Her family has no history of vascular disease.
Examination revealed a healthy, calm, young lady. Blood pressure was 140/95mmHg and a pulse rate of 90 beats per minute. The abdomen was soft. A poorly defined, pulsatile mass 12 × 8.5 cm to the left of the umbilicus was felt. We could get above the mass. There were no pulse deficits in the lower extremities. Other systems examined were normal.
Transabdominal ultrasonography confirmed a fusiform terminal abdominal aortic aneurysm 11.5 × 8.5 cm. The origins of the common iliac arteries were involved, but the renal arteries were unaffected. The aneurysm had a thick layer of thrombus on its anterior wall. The electrolytes and urea, lipid profiles, fasting blood sugar, packed cell volume and total white cell count were normal. Echocardiography, electrocardiography and a chest X-ray confirmed an enlarged left ventricle.
She was prepared for and had exploratory laparotomy while been monitored. Findings were a fusiform swelling of the terminal abdominal aorta involving the origins of the common iliac arteries and measured 11.5 × 8.7 cm [Figure 1]. The renal arteries were not involved. The aneurysm was exposed, a size 18 bifurcate graft was preclotted, heparin was given and clamps applied distal to the origin of the renal arteries on the aorta and common iliac arteries. The anterior wall of the aneurysm was incised longitudinally, the thrombus evacuated and the openings of the lumbar arteries over sewn. The neck of the aneurysm was identified and the sac incised on each side to get a clear view of the proximal anastomosis site. The bifurcate graft was laid and sutured in position proximally using 3/0 prolene [Figure 2]. The aortic clamp was released to flush the graft and then cross-clamp. The limbs of the bifurcate were anastomosed to the common iliac vessels using 4/0 prolene. Before the anastomoses were completed, the clamps on the iliac arteries and the aorta were released to back bleed the vessels and flush out clots respectively. The margin of the wall of the aneurysm sac was trimmed and the remaining sac sutured over the graft. The effect of heparin was reversed with protamine sulfate.{Figure 1}{Figure 2}
The abdomen was cleaned and closed. She had transfusion of two units of blood postoperatively. She made a steady but progressive recovery and was discharged 14 days after surgery. Ultrasound studies six weeks and six months revealed a patent graft and well perfused lower extremities. She is taking antihypertensive for mild elevation of blood pressure.
Case 3
H. S. was a 56-year-old military personnel who presented to the unit with a four-year history of a paraumbilical mass and one-year history of progressive painful mass. The swelling was noticed while he was bathing and has since increased in size. Pain was constant and did not radiate. He had no history of abdominal trauma or abdominal surgery. He smoked cigarette and drank alcohol for several years while in service. He was not a known hypertensive or diabetic.
Examination revealed a healthy looking middle aged man. Blood pressure was 145/90mmHg and a pulse rate of 89 beats per minute. A slightly tender pulsatile central lower abdominal mass 14 × 10.3 cm was felt. We could get above the mass. There were no lower limbs pulse deficits. Other systems examined were normal.
Transabdominal ultrasonography revealed a terminal abdominal aortic aneurysm 14.5 × 10.4 cm. It had a thick wall suspected to be thrombus. It was difficult to determine if the renal arteries were involved but the common iliac arteries were not involved. The electrolyte and urea, lipid profile, fasting blood sugar, packed cell volume and total white cell count were normal. Echocardiography and electrocardiography and chest X-ray showed a left ventricular enlargement. He was prepared for and had exploratory laparotomy and a repair of the aneurysm. At surgery the ultrasound findings were confirmed. The inferior mesenteric artery was involved but the renal arteries were spared. The aneurysm was exposed and the inferior mesenteric artery ligated.
The largest available graft was preclotted. Heparin (10,000IU) was administered and the aorta and common iliac arteries were cross clamped. The anterior wall of the aneurysm was incised and the contents evacuated. The openings of the lumbar arteries were over sewn. The tubular graft was laid and sutured in position proximally and distally using 3/0 prolene. The wall of the aneurysm was sutured over the graft. The effect of heparin was reversed with protamine sulfate. Abdominal closure was done. Twenty-four hours postoperatively, he had marked elevation of blood pressure, focal fits and stroke. He died 48 h postoperatively. A postmortem was not done to confirm the cause of death.
Discussion
Aneurysms are more common amongst the Caucasian population and AAA predominates. [4],[5] Abdominal aortic aneurysms are present in 2% of non-selected western elderly population and the incidence is increasing. [9] It is commonly a disease of men with cigarette smoking as the systemic risk factor. In our experience, symptomatic aortic aneurysms are generally uncommon in our practice with occasional cases reported in the literature. [10],[11],[12] Our three cases seen in indigenous African Blacks within a period of four years suggest that AAA may be more common than hitherto perceived. The three patients were sixty years and below and had hypertensive disease while one was both hypertensive and diabetic. Africa's recent economic growth has created an emerging middle class who adopts detrimental western lifestyle choices such as smoking, sedentary lifestyle and increased consumption of western-type fast food heavy in saturated fat, salt and sugar. These in addition to high longevity have led to the emergence of the so-called "lifestyle diseases" such as hypertension, atherosclerosis, etc. that are risk factors for aortic aneurysm.
The involvement of abdominal aorta in our three patients resembles the regional distribution of aortic aneurysm in white population and implies that atherosclerosis as an etiologic factor in cardiovascular disease may be an established problem in our environment. The observed ethnic variation in the distribution of aortic aneurysm with an increased involvement of the thoracic aorta is also a pointer to the seemingly increasing importance of ethiopathogenic factors operational in black African populations such as non-specific aortoarteritis, tuberculous arteritis, syphilis, bacterial infectious connective tissue diseases and HIV.
The diagnosis of AAA should not pose a challenge since ultrasound, which is available in most tertiary health institutions, is the most useful and least expensive screening method and can accurately measure the size and identify the position of aneurysm of the infrarenal aorta. Its wide application in the investigations of other abdominal diseases should also increase the pickup rates of asymptomatic AAA. Ultrasound, however, may not always provide all information that are relevant for AAA repair since it will not always detect renal arteries involvement which is critical to deciding the approach to the aneurysm repair. This is because large aneurysms of the types in our report tend to displace surrounding bowels superiorly and subsequently covering the renal arteries origins. Diligent scanning techniques involving multiple positions and numerous transducer angulations is necessary for adequate visualization of the renal artery origins (Cases I and II). [12] Where the involvement of these branched vessels origins cannot be excluded and aortography cannot also be performed, involvement of renal artery origins can then be assumed when it is not possible to palpate the upper limit of the aneurysm below the xiphisternum with the patient lying flat (only 5% of cases). [2] Employing this logical principle, we could exclude renal artery origins in case III. Computer tomography (CT) and magnetic resonance imaging (MRI) are non-invasive and complementary to aortography in detecting branched vessels involvement but are often not available and can be afforded by few patients.
Abdominal aortic aneurysm is a potentially fatal condition, for which the proper treatment is elective surgery before rupturing occurs. Treatment should be particularly considered for any aneurysm of 6 cm or more in size and when there is tenderness or rapid enlargement (>0.5c-1.0 cm) per year). [13],[14],[15] Designing a procedure for repair of an aneurysm should be based on investigative findings on either aortography, CT or MRI. Our decisions were taken based on clinical and ultrasound findings with reasonable level of success as the above investigations were not available. Besides the absence of full complement of these investigative modalities, the greatest challenge is often the non-availability of synthetic graft required for repair. When the grafts are available, the appropriate sizes might not be at hand to choose from. This we believe was responsible for the gradual but marked elevation of blood pressure, stroke and death in case III.
One important issue in aortic aneurysm management is the effects of clamping and unclamping. Occluding the aorta increases aortic impedance proximal to the clamp with elevated aortic blood pressure, left ventricular (LV) wall stress and reduced LV ejection fraction leading to LV dilatation, pulmonary edema and intracranial hypertension when prolonged. Adequate intra-operative monitoring of patient is required with the use of vasoactive drugs, vasodilators and appropriate choice of anaesthetic agents like isoflurane for decompression. Below the clamp, ischemic damage can occur with possible renal, spinal cord or extremities ischamia. Protective intraoperative measures include identification and preservation of vital blood vessels supply to the spinal cord, cross-clamp time within 30 min and employing mild hypothermia (34-35°C). These effects of aortic cross clamping is generally more pronounced in high level cross-clamping particularly in acute dissection with no collaterals, among the elderly and clamping for well about 30 min. There were no significant untoward effects noted among our patients to warrant further post-operative management probably due to short clamping time, relatively young age of the patients and infrarenal nature of the lesions.
We have outlined the challenges, evaluation and treatment of AAA with good outcome in a non-specialized unit of a health institution with limited resources. Our report serves to emphasize the need for more vigilance as AAA may not be entirely rare in our environment as previously perceived, consequent upon the increasing adoption of western lifestyles and diet, higher longevity and prevalence of infectious diseases including HIV as important etiologic factors. Since AAA are mostly asymptomatic, regular abdominal palpation aptly followed by ultrasound screening among the elderly (above 60 years) and those with risk factors for AAA (smoking, diabetes and hypertension etc) should increase early detection and prevent late presentation with extremely large lesions and inherent fatality as seen in our series. Well-harnessed resources and availability of relevant materials remain essential to successful outcome.
Acknowledgement
We acknowledge with thanks the free donation of synthetic grafts used for the repair of the aneurysms in these patients by ECWA Evangel Hospital, Jos, Nigeria and the World Health Mission. We are also grateful to the Operating Room and Intensive Care Unit staff for their tireless efforts in the care of these patients. Our indebtedness is to Mr. Chime who has continued to provide the secretarial work for our articles including this.
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