A 59-year old man presented with abdominal aortic aneurysm (AAA), discovered on duplex scan examination of the abdomen. The AAA was 60-mm large and infrarenal. The patient was otherwise asymptomatic, with no abdominal or back pain.
His medical history was significant for hypertension controlled by bitherapy, non-insulin-dependent diabetes diagnosed 5 years previously, claudication with walking distance of 400m, and a smoking history of 40 packs/year.
He had no history was significant for myocardial infarction (MI) or angina pectoris. He had a positive family history for an aneurysm. His father underwent surgery 20 years earlier for abdominal aneurysm. He also has a brother who is 70 years old and a sister who is 55 years old with apparently no health problems.
On examination, the patient was obese. Infraumbilical pulsatile mass was palpated. Routine blood tests were normal except for serum creatinine level, which was 200mg/ml. ECG was normal.
1. Define aneurysm, how do you classify them.
Dilatation of localized segment in arterial systems which usually takes place in the major arteries such as aorta, iliac, femoral, popliteal, subclavian, axillary and carotid.
Classification of aneurysm can be divided according to:
a. True (involve all three layers of the vessel : intima, media and adventitia)
b. False (involve single layer of fibrous tissue)
b. Mycotic (bacterial rather than fungal)
c. Collagen disease
(Bailey & Love’s : Short practice to surgery. 25th Edition)
2. Outline the Pathophysiology
(Robins Basic Pathology, 7th Edition)
3. You are the houseman in charge of the patient. Outline your management.
The management should include the investigation and treatment of the patients. Under investigation, following are the test which can be done:
- CBC count with differential: This study is used to assess transfusion requirements and the possibility of infection.
- Blood chemistries (including a renal and liver panel): Ascertain the integrity of renal and hepatic function to best manage the patient postoperatively and to assess operative risk.
- Type and crossmatch blood: Prepare for the possibility of transfusion, including clotting factors and platelets.
- Urinalysis: Because synthetic material is used in the intervention, assess and eliminate potential foci of infection preoperatively.
- Arterial blood gases: Assess pulmonary function preoperatively in order to determine operative risk and postoperative care. Patients who can climb a flight of stairs without excessive shortness of breath generally do well. If in doubt about the patient's pulmonary status, blood gas tests and pulmonary function tests are helpful.
- Chest radiography: This study is used to gain a preliminary assessment of the status of the heart and lungs. Concurrent pulmonary or cardiac disease may need to be addressed prior to treating the aneurysm.
- Abdominal ultrasonography: This study is used as a preliminary determination of aneurysm presence, size, and extent. It is a cost-effective modality for monitoring patients whose aneurysms are too small for surgical intervention.
- CT scanning: This study helps more clearly define the anatomy of the aneurysm and other intra-abdominal pathologies.
- Although sizing the aneurysm is important, the anatomic relationships important to surgery are also determined, ie, location of the renal arteries, length of the aortic neck, condition of the iliac arteries, and anatomic variants such as a retroaortic left renal vein or horseshoe kidney.
- Enhanced spiral CT scanning of the abdomen and pelvis with multiplanar reconstruction and CT angiography is the test of choice for preoperative evaluation for open and endovascular repair. Nonenhanced CT scanning is used to size aneurysms.
- Magnetic resonance angiography: This imaging modality is quickly replacing the traditional angiographic assessment of aneurysms. The study provides excellent anatomical definition and 3-dimensional assessment of the problem. Gadolinium-enhanced magnetic resonance angiography can provide excellent images, even though regional variations in quality are reported.
- Angiography: This imaging modality remains the criterion standard for the diagnosis of AAA, and it is indicated in the presence of associated renal or visceral involvement, peripheral occlusive disease, or aneurysmal disease. Angiography is also essential with any renal abnormality (eg, horseshoe kidney, pelvic kidney).
Low risk Moderate risk High risk
Expansion <0.3>0.6 cm/y
Smoking/COPD None, mild Moderate Severe / steroids
Family history No relatives One relative Numerous relatives
Hypertension Normal blood pressure Controlled Poorly controlled
Shape Fusiform Saccular Very eccentric
Wall stress Low (35 N/cm2 Mdm. (40 N/cm2 High (45 N/cm2)
Gender ... Male Female
4. How do you optimize the patient's condition before surgery?
• Risk reduction such as smoking cessation 48 hour before the surgery.
• Type and crossmatch blood as preparation for blood transfusion.
• Administer prophylactic antibiotics (cefazolin, 1 g intravenous piggyback).
• Insert a Foley catheter.
• Establish large-bore intravenous access.
• Monitor central venous pressure or establish Swan-Ganz catheterization (if indicated).
• Prepare the skin from the nipples to the mid thigh.
• Administer general anesthesia (with or without epidural anesthesia).
• Insert a nasogastric tube.
5. What are the options of treatment?
The definitive treatment for an aortic aneurysm is surgical repair of the aorta. This typically involves opening up of the dilated portion of the aorta and insertion of a synthetic (Dacron or Gore-Tex) patch tube. Once the tube is sewn into the proximal and distal portions of the aorta, the aneurysmal sac is closed around the artificial tube. Instead of sewing, the tube ends, made rigid and expandable by nitinol wireframe, can be much more simply and quickly inserted into the vascular stumps and there permanently fixed by external ligature.
The determination of when surgery should be performed is complex and case-specific. The overriding consideration is when the risk of rupture exceeds the risk of surgery. The diameter of the aneurysm, its rate of growth, the presence or absence of Marfan syndrome or similar connective tissue disorders, and other coexisting medical conditions are all important factors in the determination.
A rapidly expanding aneurysm should be operated on as soon as feasible, since it has a greater chance of rupture. Slowly expanding aortic aneurysms may be followed by routine diagnostic testing (i.e.: CT scan or ultrasound imaging). If the aortic aneurysm grows at a rate of more than 1 cm/year, surgical treatment should be electively performed. The current treatment guidelines for abdominal aortic aneurysms suggest elective surgical repair when the diameter of the aneurysm is greater than 5 cm.
Medical treatment may help to control the co-morbid factors, thus slowing the expansion rate. However, this does not treat the aneurysm per se but rather slow the progression of the disease.
6. If he presented to you with severe back pain and hypotension, how does you management differ?
Severe back pain and hypotension indicate rupture abdominal aorta, possibly posteriorly into the retroperitoneum cavity, thus warrant for emergency operative procedure. Diagnosis should be made as early as possible which usually is done only on clinical ground. Imaging studies may be not necessary immediate resuscitation with oxygen, intravenous replacement therapy and central line are needed. Systolic pressure should be maintained not more than 100mmHg. The use of beta blocker may be required to achieve this goal. Urinary catherer should be set up. If the patient stable, the surgery can be delayed until cross match of 6 units of blood is ready but the patient needs to be transferred to operating room immediately so that the procedure can be commenced immediately if haemodynamic instability develops.
kalau ada sebarang kesilapan, atau cdgn lebih class gitu, sila aju kan k.. hehe.. thanks