Principles of surgery

PART II
Specific Considerations

CHAPTER 23
Arterial Disease

BASIC SCIENCE QUESTIONS

1. The normal ratio between the blood pressure in the brachial artery and the distal arteries of the leg is

A. 0.8

B. 0.8

C. 1.0

D. >1.0

Answer: D

The ABI is determined in the following ways. Blood pressure (BP) is measured in both upper extremities using the highest systolic BP as the denominator for the ABI. The ankle pressure is determined by placing a BP cuff above the ankle and measuring the return to flow of the posterior tibial and dorsalis pedis arteries using a pencil Doppler probe over each artery. The ratio of the systolic pressure in each vessel divided by the highest arm systolic pressure can be used to express the ABI in both the posterior tibial and dorsalis pedis arteries (Fig. 23-1). Normal is more than 1. (See Schwartz 9th ed., p 704.)

Image

FIG. 23-1. Calculating the ankle-brachial index.

2. Collateral flow between the celiac artery and superior mesenteric artery is primarily through the

A. Arc of Riolan

B. Meandering mesenteric arteries

C. Pancreaticoduodenal arteries

D. Marginal artery of Drummond

Answer: C

Collateral networks between the celiac artery (CA) and the superior mesenteric artery (SMA) exist primarily through the superior and inferior pancreaticoduodenal arteries. The inferior mesenteric artery (IMA) may provide collateral arterial flow to the SMA through the marginal artery of Drummond, the arc of Riolan, and other unnamed retroperitoneal collateral vessels termed meandering mesenteric arteries. (See Schwartz 9th ed., p 731.)

3. Mutations in the ATP-binding cassette subfamily C member 6 (ABCC6) gene are found in patients with

A. Ehlers-Danlos syndrome

B. Pseudoxanthoma elasticum

C. Takayasu’s arteritis

D. Marfan syndrome

Answer: B

Pseudoxanthoma elasticum is a rare inherited disorder of connective tissue that is characterized by an unbalanced elastic fiber metabolism and synthesis, resulting in fragmentation and calcification of the fibers. Clinical manifestations occur in the skin, ocular, GI, and cardiovascular systems. Characteristic skin lesions are seen in the axilla, antecubital and popliteal fossae, and groin. The yellow, xanthoma-like papules occur in redundant folds of skin and are said to resemble plucked chicken skin. The inheritance pattern includes both autosomal dominant and recessive types and has a prevalence of one in 160,000 individuals. The ATP-binding cassette subfamily C member 6 (ABCC6) gene has been demonstrated to be responsible, and 43 mutations have been identified, all of which lead to calcification of the internal elastic laminae of medium-sized vessel walls.

Ehlers-Danlos syndrome is a disorder of fibrillar collagen metabolism with identifiable, specific defects that have been found in the collagen biosynthetic pathway that produce clinically distinct forms of this disease.

Takayasu’s arteritis is a rare but well-recognized chronic inflammatory arteritis affecting large vessels, predominantly the aorta and its main branches.

Marfan syndrome is characterized by abnormal musculoskeletal, ocular, and cardiovascular features first described by Antoine Marfan in 1896. The inborn error of metabolism in this syndrome has been localized to the long arm of chromosome 15 (15q21.3). Defects occur in fibrillin, a basic protein in the microfibrillar apparatus that serves as a backbone for elastin, which is one of the main extracellular structural proteins in blood vessels. (See Schwartz 9th ed., p 767.)

4. The superficial peroneal nerve is located in the

A. Anterior compartment

B. Lateral compartment

C. Superficial posterior compartment

D. Deep posterior compartment

Answer: B

The superficial peroneal nerve is located in the lateral compartment. The deep peroneal nerve is located in the anterior compartment. (See Schwartz 9th ed., p 757, and Table 23-1.)

TABLE 23-1 Fascial compartments of the lower leg

Image

5. The origin of the carotid body is

A. Ectoderm

B. Mesoderm

C. Endoderm

D. Neural crest cells

Answer: D

The carotid body originates from the third branchial arch and from neuroectodermal-derived neural crest lineage. The normal carotid body is located in the adventitia or peri-adventitial tissue at the bifurcation of the CCA. The gland is innervated by the glossopharyngeal nerve. Its blood supply is derived predominantly from the external carotid artery, but also can come from the vertebral artery. Carotid body tumor is a rare lesion of the neuroendocrine system. Other glands of neural crest origin are seen in the neck, parapharyngeal spaces, mediastinum, retroperitoneum, and adrenal medulla. Tumors involving these structures have been referred to as paraganglioma, glomus tumor, or chemodectoma. (See Schwartz 9th ed., p 721.)

CLINICAL QUESTIONS

1. Approximately what percentage of vascular patients are diabetic?

A. 5%

B. 15%

C. 30%

D. 50%

Answer: C

Appropriate history should be focused on the presenting symptoms related to the vascular system (Table 23-2). Of particular importance in the previous medical history is noting prior vascular interventions (endovascular or open surgical), and all vascular patients should have inquiry made about their prior cardiac history and current cardiac symptoms. Approximately 30% of vascular patients will be diabetic. A history of prior and current smoking status should be noted. (See Schwartz 9th ed., p 703.)

TABLE 23-2 Pertinent elements in vascular history

• History of stroke or transient ischemic attack

• History of coronary artery disease, including previous myocardial infarction and angina

• History of peripheral arterial disease

• History of diabetes

• History of hypertension

• History of tobacco use

• History of hyperlipidemia

2. The most common type of fibromuscular dysplasia of the carotid artery is

A. Intimal fibroplasia

B. Medial fibroplasia

C. Premedial dysplasia

D. Medial hyperplasia

Answer: B

Four histological types of fibromuscular dysplasia (FMD) have been described in the literature. The most common type is medial fibroplasia, which may present as a focal stenosis or multiple lesions with intervening aneurysmal outpouchings. The disease involves the media with the smooth muscle being replaced by fibrous connective tissue. Commonly, mural dilations and microaneurysms can be seen with this type of FMD. Medial hyperplasia is a rare type of FMD, with the media demonstrating excessive amounts of smooth muscle. Intimal fibroplasia accounts for 5% of all cases and occurs equally in both sexes. The media and adventitia remain normal, and there is accumulation of subendothelial mesenchymal cells with a loose matrix of connective tissue causing a focal stenosis in adults. Finally, premedial dysplasia represents a type of FMD with elastic tissue accumulating between the media and adventitia. (See Schwartz 9th ed., p 720.)

3. Which of the following types of stents would be the best choice for a long segment stenosis of the internal carotid artery?

A. Self-expanding stent

B. Stent graft

C. Balloon-expandable stent

D. Drug-eluting stent

Answer: A

Self-expanding stents generally come in longer lengths than balloon-expandable stents and are therefore used to treat long and tortuous lesions. Their ability to continually expand after delivery allows them to accommodate adjacent vessels of different size. This makes these stents ideal for placement in the internal carotid artery (ICA). (See Schwartz 9th ed., p 711.)

4. The conduit of choice for infrainguinal bypass grafting is

A. Autogenous vein

B. Human umbilical vein

C. PTFE

D. Dacron

Answer: A

Autogenous vein is superior to prosthetic conduits for all infrainguinal bypasses, even in the above-knee (AK) position. This preference is applicable not only for the initial bypass but also for reoperative cases. For long bypasses, ipsilateral great saphenous vein (GSV), contralateral GSV, small saphenous vein, arm vein, and spliced vein are used, in decreasing order of preference. (See Schwartz 9th ed., p 765.)

5. Which of the following is NOT one of the characteristics evaluated to determine if a patient is a candidate for endovascular repair of an abdominal aortic aneurysm?

A. Neck length

B. Neck mural calcification

C. Common iliac artery length

D. Common iliac artery calcification

Answer: D

Anatomic eligibility for endovascular repair is mainly based on three areas: the proximal aortic neck, common iliac arteries (CIAs), and the external iliac and common femoral arteries, which relate to the proximal and distal landing zones or fixation sites and the access vessels, respectively. See Table 23-3 for specific characteristics used to establish anatomic eligibility for endovascular repair. (See Schwartz 9th ed., p 727.)

TABLE 23-3 Ideal characteristics of an aneurysm for endovascular abdominal aortic aneurysm repair

Image

6. The risk of stroke is markedly increased in patients who have a decrease in internal carotid artery (ICA) luminal diameter of

A. 40%

B. 50%

C. 60%

D. 70%

Answer: D

With increasing degree of stenosis in the ICA, flow becomes more turbulent, and the risk of atheroembolization escalates. The severity of stenosis is commonly divided into three categories according to the luminal diameter reduction: mild (less than 50%), moderate (50 to 69%), and severe (70 to 99%). Severe carotid stenosis is a strong predictor for stroke. (See Schwartz 9th ed., p 712.)

7. Which of the following patients should be offered revascularization (endoluminal or by endarterectomy) of their carotid stenosis?

A. Symptomatic patient with 35% unilateral stenosis

B. Symptomatic patient with 35% bilateral stenosis

C. Asymptomatic patient with 80% unilateral stenosis

D. None of the above

Answer: C

In patients with symptomatic carotid stenosis, the degree of stenosis appears to be the most important predictor in determining risk for an ipsilateral stroke. The risk of a recurrent ipsilateral stroke in patients with severe carotid stenosis approaches 40%.

It is generally agreed that asymptomatic patients with severe carotid stenosis (80 to 99%) are at significantly increased risk for stroke and stand to benefit from either surgical or endovascular revascularization. However, revascularization for asymptomatic patients with a less severe degree of stenosis (60 to 79%) remains controversial. (See Schwartz 9th ed., p 715.)

8. Which of the following is NOT a cause of intermittent claudication?

A. Popliteal cyst

B. Takayasu’s disease

C. Popliteal entrapment

D. Acute radiation injury

Answer: D

See Table 23-4 for additional non-atherosclerotic causes of intermittent claudication. (See Schwartz 9th ed., p 754.)

TABLE 23-4 Non-atherosclerotic causes of intermittent claudication

• Aortic coarctation

• Arterial fibrodysplasia

• Iliac syndrome of the cyclist

• Peripheral emboli

• Persistent sciatic artery

• Popliteal aneurysm

• Popliteal cyst

• Popliteal entrapment

• Primary vascular tumors

• Pseudoxanthoma elasticum

• Remote trauma or radiation injury

• Takayasu’s disease

• Thromboangiitis obliterans

9. When performing a four-compartment fasciotomy for compartment syndrome, medial and lateral incisions are created. Which of the following compartments is opened through the medial incision?

A. Anterior compartment

B. Deep posterior compartment

C. Peroneal compartment

D. None of the above

Answer: B

Compartment pressures are relieved in the leg by medial and lateral incisions. Through the medial incision, long openings are then made in the fascia of the superficial and deep posterior compartments. Through the lateral incision, the anterior and peroneal compartments are opened. (See Schwartz 9th ed., p 757, and Fig. 23-2.)

Image

FIG. 23-2. Schematic illustration of fascial compartments of the lower extremity.

10. Amaurosis fugax is a symptom of occlusion of the

A. Posterior cerebral artery

B. Circle of Willis

C. Internal carotid artery

D. External carotid artery

Answer: C

The common ocular symptoms associated with extracranial carotid artery occlusive disease include amaurosis fugax and presence of Hollenhorst plaques. Amaurosis fugax, commonly referred to astransient monocular blindness, is a temporary loss of vision in one eye that patients typically describe as a window shutter coming down or gray shedding of the vision. This partial blindness usually lasts for a few minutes and then resolves. Most of these phenomena (>90%) are due to embolic occlusion of the main artery or the upper or lower divisions. Monocular blindness progressing over a 20-minute period suggests a migrainous etiology. Occasionally, the patient will recall no visual symptoms while the optician notes a yellowish plaque within the retinal vessels, which is also known as theHollenhorst plaque. These are frequently derived from cholesterol embolization. (See Schwartz 9th ed., p 713.)

11. The average annual growth of abdominal aortic aneurysms is approximately

A. 1 mm

B. 3 mm

C. 1 cm

D. 3 cm

Answer: B

The natural history of an abdominal aortic aneurysm (AAA) is to expand and rupture. AAA exhibits a ‘staccato’ pattern of growth, where periods of relative quiescence may alternate with expansion. Therefore, although an individual pattern of growth cannot be predicted, average aggregate growth is approximately 3 to 4 mm/y. There is some evidence to suggest that larger aneurysms may expand faster than smaller aneurysms, but there is significant overlap between the ranges of growth rates at each strata of size. (See Schwartz 9th ed., p 723.)

12. What is the approximate 90-day risk of a stroke in a patient with a transient ischemic attack?

A. 2%

B. 10-15%

C. 25-30%

D. 40-50%

Answer: B

Conventionally, patients with carotid bifurcation occlusive disease are divided into two broad categories: patients without prior history of ipsilateral stroke or transient ischemic attack (TIA) (asymptomatic) and those with prior or current ipsilateral neurologic symptoms (symptomatic). It is estimated that 15% of all strokes are preceded by a TIA. The 90-day risk of a stroke in a patient presenting with a TIA is 3 to 17%. (See Schwartz 9th ed., p 715.)

13. Which of the following is the “gold standard” for the diagnosis of renal artery hypertension?

A. Captopril renal scanning

B. Renal artery duplex ultrasonography

C. Selective angiography

D. MRA with IV gadolinium

Answer: C

Digital subtraction angiography (DSA) remains the gold standard to assess renal artery occlusive disease. A flush aortogram is performed first so that any accessory renal arteries can be detected and the origins of all the renal arteries are adequately displayed. The presence of collateral vessels circumventing a renal artery stenosis strongly supports the hemodynamic importance of the stenosis. A pressure gradient of 10 mmHg or greater is necessary for collateral vessel development, which also is associated with activation of the renin-angiotensin cascade.

Captopril renal scanning is a functional study that assesses renal perfusion before and after administration of the ACE inhibitor captopril. Captopril inhibits the secretion of angiotensin II. Through this mechanism it reduces the efferent arteriole vasoconstriction and, as a result, the glomerular filtration rate (GFR). The test consists of a baseline renal scan, and a second renal scan after captopril administration. Positive result indicates that captopril administration (a) increases the time to peak activity to more than 11 minutes or (b) increases the GFR ratio between sides to greater than 1.5:1 compared to a normal baseline scan.

Renal artery duplex ultrasonography is a noninvasive test of assessing renal artery stenosis both by visualization of the vessel and measurement of the effect of stenosis on blood flow velocity and waveforms. The presence of a severe renal artery stenosis correlates with peak systolic velocities of >180 cm/s and the ratio of these velocities to those in the aorta of >3.5.

Magnetic resonance angiography (MRA) with IV gadolinium contrast enhancement has been increasingly used for renal artery imaging because of its ability to provide high-resolution images (Figs. 23-3 and 23-4) while using a minimally nephrotoxic agent. Flow void may be inaccurately interpreted as occlusion or stenosis in MRA. Therefore, unless the quality of the image analysis software is superior, MRA should be interpreted with caution and used in conjunction with other modalities before making plans for operative or endovascular treatment. (See Schwartz 9th ed., p 738.)

Image

FIG. 23-3. Magnetic resonance angiography of the abdominal aorta revealed bilateral normal renal arteries.

Image

FIG. 23-4. Magnetic resonance angiography of the abdominal aorta revealed bilateral ostial renal artery stenosis (arrows).

14. Which of the following is NOT a complication of temporal arteritis?

A. Aortic dissection

B. Blindness

C. Jaw claudication

D. Temporal aneurysm

Answer: D

The clinical syndrome of temporal arteritis (giant cell arteritis) begins with a prodromal phase of constitutional symptoms, including headache, fever, malaise, and myalgia. As a result of vascular narrowing and endorgan ischemia, complications may occur such as visual alterations, including blindness and mural weakness, resulting in acute aortic dissection that may be devastating. Ischemic optic neuritis resulting in partial or complete blindness occurs in up to 40% of patients and is considered a medical emergency. Cerebral symptoms occur when the disease process extends to the carotid arteries. Jaw claudication and temporal artery tenderness may be experienced. Aortic lesions usually are asymptomatic until later stages and consist of thoracic aneurysms and aortic dissections. (See Schwartz 9th ed., p 767.)

15. Which of the following is a contraindication to carotid artery stenting?

A. 1.5-cm segment of stenosis

B. >80% occlusion of the luminal diameter

C. Extensive calcification

D. Occluded middle cerebral artery

Answer: C

There are anatomical conditions based on angiographic evaluation in which carotid artery stenting should be avoided due to increased procedural-related risks (Table 23-5). (See Schwartz 9th ed., p 719.)

TABLE 23-5 Unfavorable carotid angiographic appearance in which carotid stenting should be avoided

• Extensive carotid calcification

• Polypoid or globular carotid lesions

• Severe tortuosity of the common carotid artery

• Long segment stenoses (>2 cm in length)

• Carotid artery occlusion

• Severe intraluminal thrombus (angiographic defects)

• Extensive middle cerebral artery atherosclerosis

16. When compared to open repair of an abdominal aortic aneurysm, endovascular repair

A. Requires lifelong follow-up imaging

B. Results in an increased transfusion requirement

C. Costs about the same

D. Results in longer ICU stays

Answer: A

Lifelong follow-up is essential to the long-term success after endovascular AAA repair. Indeed, one may go so far as to say that absence of appropriate follow-up is tantamount to not having had a repair at all. A triple-phase (noncontrast, contrast, delayed) spiral CT scan and a four-view (anteroposterior, lateral, and two obliques) abdominal x-ray should be obtained within the first month. Subsequent imaging can be obtained at 6-month intervals in the first 1 to 2 years and yearly thereafter.

The primary success rate after endovascular repair of AAA has been reported to be as high as 95%. The less invasive nature of this procedure is appealing to many physicians and patients. In addition, virtually all reports indicate decreased blood loss, transfusion requirements, and length of ICU and hospital stay for endovascular repair of AAAs when compared to the standard surgical approach. With the advent of bifurcated grafts and improved delivery systems in the future, the only real limitation will be cost. (See Schwartz 9th ed., p 728.)

The in-hospital costs for both endovascular and open repair include graft cost, OR fees, radiology, pharmacy, ancillary care, ICU charges, and floor charges. Despite the improved morbidity and mortality rates, several early studies have reported no cost benefit with the application of endovascular repair. The limiting factor appears to be the cost of the device. Despite commercialization of endovascular repair, the device costs are still in the range of $5000 to $6000 with no signs of abating. A recent report by Angle and associates further corroborates previous studies. In their review,despite decreased hospital and ICU stays and use of pharmacy and respiratory services, cost of endovascular repair was 1.74 times greater than the standard surgical approach. (See Schwartz 9th ed., p 729.)

17. Type 1 aortoiliac disease is associated with

A. Diabetes

B. Hypertension

C. Hyperlipidemia

D. Elevated levels of homocysteine

Answer: C

Type I aortoiliac disease, which occurs in 5 to 10% of patients, is confined to the distal abdominal aorta and common iliac vessels. This type of aortoiliac occlusive disease occurs in a relatively younger group of patients (aged in their mid-50s), compared with patients who have more femoropopliteal disease. Patients with a type I disease pattern have a lower incidence of hypertension and diabetes, but a significant frequency of abnormal blood lipid levels, particularly type IV hyperlipoproteinemia.

Type II aortoiliac disease represents a more diffuse atherosclerotic progression that involves predominately the abdominal aorta with disease extension into the CIA.

Type III aortoiliac occlusive disease, which affects approximately 65% of patients with aortoiliac occlusive disease, is widespread disease that is seen above and below the inguinal ligament. (See Schwartz 9th ed., p 744, and Fig. 23-5.)

Image

FIG. 23-5. Aortoiliac disease can be classified into three types. Type I represents focal disease affecting the distal aorta and proximal common iliac artery. Type II represents diffuse aortoiliac disease above the inguinal ligament. Type III represents multisegment occlusive disease involving aortoiliac and infrainguinal arterial vessels.

18. Which of the following patients should undergo elective repair of an asymptomatic abdominal aortic aneurysm?

A. A man with a 4.5-cm aneurysm

B. A woman with a 5.0-cm aneurysm

C. A man with an aneurysm that has grown 0.5 cm in the last year

D. A woman with an aneurysm that has grown 0.5 cm in the last year

Answer: B

Based on best available evidence, the annualized risk of rupture is given in Table 23-6. The rupture risk is quite low for aneurysms 5.5 cm and begins to rise exponentially thereafter. This size can serve as an appropriate threshold for recommending elective repair provided one’s surgical mortality is below 5%. For each size strata, however, women appear to be at higher risk for rupture than men, and a lower threshold of 4.5 to 5.0 cm may be reasonable in good-risk patients. Although data are less compelling, a pattern of rapid expansion of >0.5 cm within 6 months can be considered a relative indication for elective repair. (See Schwartz 9th ed., p 723.)

TABLE 23-6 Annualized risk of rupture of abdominal aortic aneurysm (AAA) based on size

Image

a The estimated 5-y risk is more than five times the estimated annual risk because over that 5 y, the AAA, if left untreated, will continue to grow in size.

19. Carotid artery stenting is indicated for patients who are at “high risk” for endarterectomy. Which of the following is NOT one of the criteria for a high-risk patient?

A. Age >70 years

B. Previous neck irradiation

C. Severe chronic obstructive pulmonary disease

D. End stage renal disease on dialysis

Answer: A

Since carotid artery stenting was approved by the FDA in 2004 for clinical application, this percutaneous procedure has become a treatment alternative in patients who are deemed ‘high-risk’ for endarterectomy (Table 23-7). Patients older than 80 years of age are considered high risk. (See Schwartz 9th ed., p 716.)

TABLE 23-7 Conditions qualifying patients as “high surgical risk” for carotid endarterectomy

Image

20. Approximately what percent of carotid body tumors are familial in origin?

A. 2%

B. 10%

C. 35%

D. 50%

Answer: C

Approximately 5 to 7% of carotid body tumors are malignant. Although chronic hypoxemia has been invoked as a stimulus for hyperplasia of carotid body, approximately 35% of carotid body tumors are hereditary. The risk of malignancy is greatest in young patients with familial tumors. (See Schwartz 9th ed., p 722, and Fig. 23-6.)

Image

FIG. 23-6. A. A carotid body tumor (arrow) located adjacent to the carotid bulb. B. Following peri-adventitial dissection, the carotid body tumor is removed.

21. Fibromuscular dysplasia of the renal arteries

A. Occurs more commonly in men

B. Usually involves the proximal artery

C. Affects the right renal artery more often than the left

D. Is the most common cause of renovascular hypertension

Answer: C

The second most common cause of renal artery stenosis, after atherosclerosis, is fibromuscular dysplasia (FMD), which accounts for 20% of cases, and is most frequently encountered in young, often multiparous women. FMD of the renal artery represents a heterogeneous group of lesions that can produce histopathologic changes in the intima, media, or adventitia. The most common variety consists of medial fibroplasia, in which thickened fibromuscular ridges alternate with attenuated media producing the classic angiographic ‘string of beads’ appearance. The cause of medial fibroplasia remains unclear. Most common theories involve a modification of arterial smooth muscle cells in response to estrogenic stimuli during the reproductive years, unusual traction forces on affected vessels, and mural ischemia from impairment of vasa vasorum blood flow. Fibromuscular hyperplasia usually affects the distal two thirds of the main renal artery, and the right renal artery is affected more frequently than the left. (See Schwartz 9th ed., p 737, and Fig. 23-7.)

Image

FIG. 23-7. Magnetic resonance angiography of the abdominal aorta revealed the presence of a left renal artery fibromuscular dysplasia (arrows).

22. Patients with chronic mesenteric ischemia may experience

A. Pain out of proportion to physical findings

B. Bloody diarrhea

C. Fever

D. “Food fear”

Answer: D

Abdominal pain out of proportion to physical findings is the classic presentation in patients with acute mesenteric ischemia and occurs following an embolic or thrombotic ischemic event of the SMA. Other manifestations include sudden onset of abdominal cramps in patients with underlying cardiac or atherosclerotic disease, often associated with bloody diarrhea, as a result of mucosal sloughing secondary to ischemia. Fever, nausea, vomiting, and abdominal distention are some common but nonspecific manifestations. Diffuse abdominal tenderness, rebound, and rigidity are late signs and usually indicate bowel infarction and necrosis.

Clinical manifestations of chronic mesenteric ischemia are more subtle owing to the extensive collateral development. However, when intestinal blood flow is unable to meet the physiologic GI demands, mesenteric insufficiency ensues. The classic symptoms include postprandial abdominal pain, “food fear,” and weight loss. Persistent nausea, and occasionally diarrhea, may coexist. Diagnosis remains challenging, and most of the patients will undergo an extensive and expensive GI tract work-up for the above symptoms before referral to a vascular service. (See Schwartz 9th ed., p 732.)

23. Which of the following is the best initial treatment for a patient with severe acute limb ischemia?

A. Endovascular thrombolysis

B. Systemic thrombolysis

C. Surgical embolectomy

D. Anticoagulation

Answer: D

In the absence of any significant contraindication, the patient with an ischemic LE should be immediately anticoagulated. This will prevent propagation of the clot into unaffected vascular beds. IV fluid should be started and a Foley catheter inserted to monitor urine output. Baseline labs should be obtained and creatinine levels noted. A hypercoagulable work-up should be performed before initiation of heparin if there is sufficient suspicion. According to results from randomized trials, there is no clear superiority for thrombolysis over surgery in terms of 30-day limb salvage or mortality. Access to each treatment option is a major issue in the decision-making process, as time is often critical. National registry data from the United States reveal that surgery is used three- to fivefold more frequently than thrombolysis. (See Schwartz 9th ed., p 755.)

24. Which of the following ankle-brachial index would be expected in a patient with claudication?

A. 1.0

B. 0.8

C. 0.6

D. 0.4

Answer: C

There is increasing interest in the use of the ankle-brachial index (ABI) to evaluate patients at risk for cardiovascular events (Figure 23-1). An ABI 0.9 correlates with increased risk of myocardial infarction and indicates significant, although perhaps asymptomatic, underlying peripheral vascular disease. Normal is more than 1. Patients with claudication typically have an ABI in the 0.5 to 0.7 range, and those with rest pain are in the 0.3 to 0.5 range. Those with gangrene have an ABI of 0.3. These ranges can vary depending on the degree of compressibility of the vessel. The test is less reliable in patients with heavily calcified vessels. Due to noncompressibility, some patients such as diabetics and those with end-stage renal disease may have an ABI of 1.40 or greater and require additional noninvasive diagnostic testing to evaluate for peripheral arterial disease (PAD). (See Schwartz 9th ed., p 704.)

25. Which of the following is the most common type of EnDoleak after endovascular repair of an abdominal aortic aneurysm?

A. Type I

B. Type II

C. Type III

D. Type IV

Answer: B

Four types of EnDoleaks have been described (Table 23-8). Type I EnDoleak refers to fixation-related leaks that occur at the proximal or distal attachment sites. These represent less than 5% of all EnDoleaks and are seen as an early blush of contrast into the aneurysm sac from the proximal or distal ends of the device during completion angiography.

Type II EnDoleak refers to retrograde flow originating from a lumbar, inferior mesenteric, accessory renal, or hypogastric artery. They are the most common type of EnDoleak, accounting for 20 to 30% of all cases, and about one half resolve spontaneously.

Type III EnDoleaks refer to a failure of device integrity or component separation from modular systems. If detected intraoperatively or in the early perioperative period, it is usually from inadequate overlap between two stent grafts, while in the late period, it may be from a fabric tear or junctional separation from conformational changes of the aneurysm. Regardless of the etiology or timing, these should be promptly repaired.

Type IV EnDoleak refers to the diffuse, early blush seen during completion angiography due to graft porosity and/or suture holes of some Dacron-based devices. It does not have any clinical significance and usually cannot be seen after 48 hours and heparin reversal. (See Schwartz 9th ed., p 730, and Fig. 23-8.)

TABLE 23-8 EnDoleak classification

Image

Image

FIG. 23-8. Four types of EnDoleak that include: type I EnDoleak = attachment site leak; type II EnDoleak = side branch leak caused by lumbar or side branches; type III EnDoleak = endograft junctional leak due to overlapping device components; type IV EnDoleak = endograft fabric or porosity leak.

26. The 10-year patency rate for aortobifemoral bypass grafts is approximately

A. 30%

B. 50%

C. 70%

D. 90%

Answer: C

Surgical options for treatment of aortoiliac occlusive diseases consist of various configurations of aortobifemoral bypass (ABF) grafting, various types of extra-anatomic bypass grafts, and aortoiliac endarterectomy. The procedure performed is determined by several factors, including anatomic distribution of the disease, clinical condition of the patient, and personal preference of the surgeon. In most cases, ABF is performed because patients usually have disease in both iliac systems. Although one side may be more severely affected than the other, progression does occur, and bilateral bypass does not complicate the procedure or add to the physiologic stress of the operation. ABF reliably relieves symptoms, has excellent long-term patency (approximately 70 to 75% at 10 years), and can be completed with a tolerable perioperative mortality (2 to 3%). (See Schwartz 9th ed., p 745.)

27. The procedure of choice for acute thrombotic mesenteric ischemia is

A. Endovascular clot lysis and balloon angioplasty

B. Endovascular clot lysis and stenting of the superior mesenteric artery

C. Open thrombectomy with patch angioplasty

D. Open bypass of the superior mesenteric artery

Answer: D

Thrombotic mesenteric ischemia usually involves a severely atherosclerotic vessel, typically the proximal celiac artery (CA) and superior mesenteric artery (SMA). Therefore, these patients require a reconstructive procedure to the SMA to bypass the proximal occlusive lesion and restore adequate mesenteric flow. The saphenous vein is the graft material of choice, and prosthetic materials should be avoided in patients with nonviable bowel, due to the risk of bacterial contamination if resection of necrotic intestine is performed. The bypass graft may originate from either the aorta or iliac artery. (See Schwartz 9th ed., p 734.)

There are two main drawbacks with regard to thrombolytic therapy in mesenteric ischemia. Percutaneous, catheter-directed thrombolysis (CDT) does not allow the possibility to inspect the potentially ischemic intestine following restoration of the mesenteric flow. Additionally, a prolonged period of time may be necessary to achieve successful CDT, due in part to serial angiographic surveillance to document thrombus resolution. An incomplete or unsuccessful thrombolysis may lead to delayed operative revascularization, which may further necessitate bowel resection for irreversible intestinal necrosis. Therefore, catheter-directed thrombolytic therapy for acute mesenteric ischemia should only be considered in selected patients under a closely scrutinized clinical protocol. (See Schwartz 9th ed., p 735.)

28. Approximately what percentage of patients with peripheral vascular disease also have significant coronary artery disease?

A. 20%

B. 40%

C. 60%

D. 80%

Answer: B

The most important and controversial aspect of preoperative evaluation in patients with atherosclerotic disease requiring surgical intervention is the detection and subsequent management of associated coronary artery disease (CAD). Several studies have documented the existence of significant CAD in 40 to 50% or more of patients requiring peripheral vascular reconstructive procedures, 10 to 20% of whom may be relatively asymptomatic largely because of their inability to exercise. Myocardial infarction is responsible for the majority of both early and late postoperative deaths in patients with peripheral vascular disease. (See Schwartz 9th ed., p 708.)