aneurysms ranging in size from 2 to 6 cm.126,127

Treatment should be individualized for cases of rupture and elective cases for patient symptoms and

aneurysm size >2 cm. Aneurysm ligation and resection, without reconstruction, has previously been

endorsed for those patients with adequate foregut collateral circulation. Simple ligation and

transcatheter embolization may be considered as life-saving in cases of rupture, but both offer

substantial risk of perioperative hepatic and intestinal ischemia, necrosis, and patient mortality.126–128

Aneurysmectomy with arterial reconstruction remains the preferred treatment of celiac artery

aneurysms. Surgical revascularization may be accomplished by primary arterial–arterial anastomosis

following aneurysm resection, direct aortic reimplantation of the celiac artery or its branches, or

aortoceliac bypass. Prosthetic conduit may offer superior patency rates in comparison to autogenous

reversed saphenous vein, which tends to kink.127 Elective surgical repair offers patients symptomatic

relief with a 0% to 5% risk of perioperative mortality.127,128 Endovascular options for aneurysm

treatment are increasingly described including celiac artery stent grafting.129

Gastric and Gastroepiploic Artery Aneurysm

Gastric and gastroepiploic artery aneurysms account for approximately 4% to 5% of all splanchnic

aneurysms affecting men three times more frequently than women (Fig. 91-19).84 Etiologic risk factors

include primarily arterial dysplasia with segmental arterial mediolysis and periarterial inflammation

like pancreatitis and vasculitis; atherosclerosis when present is felt to be a secondary process.83,84,130

Gastric artery aneurysms are 10 times more common than gastroepiploic artery aneurysms. While

patients may present with abdominal pain, up to 90% of patients have historically presented acutely

ruptured with evidence of GI bleeding more common than intraperitoneal rupture.83,84

Figure 91-19. A: Diagnostic aortogram of an 82-year-old woman with a highly tortuous abdominal aorta, aberrant hepatic arterial

anatomy, and two sequential gastric artery aneurysms measuring 10 mm in maximum diameter. B: Completion arteriogram

following endovascular embolization.

Treatment is recommended for all gastric and gastroepiploic arterial aneurysms, regardless the size.

Arteriogram is invaluable for aneurysm identification preoperatively and operative planning. Surgical

management has historically relied on simple arterial ligation or excision without reconstruction while

intramural aneurysms required a wedge excision of involved gastric wall.84,89 Contemporary literature

would suggest that catheter-based embolization of these arteries is the new standard for care with

multiple case reports and small series documenting successful aneurysm occlusion with coils and

thrombin injection.86,131,132

Jejunal, Ileal, and Colic Artery Aneurysm

Aneurysms of the jejunal, ileal, and colic arteries account for <3% of all splanchnic aneurysms,

affecting men and women equally beyond the sixth decade of life.84 These aneurysms are associated

with medial degeneration, infection, connective tissue disorder, and polyarteritis nodosa with multiple

aneurysms identified in approximately 10% of cases.84,130,133 Atherosclerosis, when present, is felt to be

a secondary process. While patients may present with abdominal pain, most have no symptoms. Rupture

may complicate up to 30% of cases resulting in gastrointestinal bleeding and mortality rates that

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approach 20%.

Treatment is recommended for all mesenteric branch aneurysms, regardless of the size. Arteriogram is

invaluable for aneurysm identification preoperatively and operative planning. Surgical management has

historically relied on simple arterial ligation or excision without reconstruction.84 Intramural aneurysms

and those associated with bowel necrosis required resection of the involved intestine at the time of

aneurysm exclusion. Transcatheter embolization has been increasingly utilized, especially for cases of

acute rupture and GI bleeding with intestinal necrosis, perforation, and late stricture potential

complications.134–136

Gastroduodenal and Pancreaticoduodenal Artery Aneurysm

Gastroduodenal and pancreaticoduodenal artery aneurysms account for <2% of all splanchnic

aneurysm.84 Men are affected four times more often than women during the sixth decade of life.84

Periarterial inflammation resulting from pancreatitis with vascular necrosis or vessel erosion by

pseudocyst reflects the most common etiology, while additional causes include arteriosclerosis,

congenital medial degeneration, and trauma.84 Concomitant celiac artery stenosis and occlusion are

common in noninflammatory aneurysms and GDA and pancreaticoduodenal aneurysms are suggested to

represent the effect of inordinately high-volume blood flow on branchings of the collateral circulation

(Fig. 91-20).137–139 Symptoms of abdominal pain are common; additional symptoms may include gastric

outlet obstruction and compressive symptoms like nausea and emesis.120,140 Rupture is also common,

complicating up to 75% of inflammatory and 50% of noninflammatory aneurysms resulting most often

in gastrointestinal bleeding and less commonly bleeding into the biliary or pancreatic ductal systems,

peritoneum or retroperitoneum.139 Rupture-associated mortality approximates 20% to 50%.139,141 While

it remains unclear if aneurysm size is a risk factor for rupture, rupture has been described at a small

median size of 12 mm.91,138,142

Figure 91-20. CT angiogram of an 87-year-old woman with a large 3.4-cm gastroduodenal artery aneurysm associated with celiac

artery occlusion.

Open surgical repair remains appropriate for most patients. These aneurysms are most often

amenable to simple ligation, aneurysm resection, or aneurysmorrhaphy without

revascularization.86,90,94,120,139,143,144 Celiac artery revascularization should be considered in select

noninflammatory cases. Pancreatitis-associated inflammatory aneurysms may require arterial branch

ligation from within the aneurysm sac or pancreatic resection in severe cases. Transcatheter

embolization with coils, glue, thrombin, and electrocoagulation has been successfully reported,

especially for high-risk patients and those presenting with rupture.90,118,139,141,145,146

Inferior Mesenteric Artery Aneurysm

IMA aneurysms account for <1% of all splanchnic aneurysms. Our understanding of these aneurysms is

limited to case reports. Men appear to be most commonly affected.120 Atherosclerosis is the most

common etiologic factor with additional risk factors including infection, polyarteritis nodosa,

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inflammatory arteritides, segmental arterial mediolysis, Behçet disease, and neurofibromatosis.147

Concomitant celiac and SMA occlusion is common; it has been hypothesized that turbulent blood flow

through tortuous marginal arteries originating from the IMA results in a high-flow state, or “jet disorder

phenomenon,” and subsequent dilation of the IMA and small collaterals which can lead to weakness of

the arterial wall and aneurysmal disease.147–150 Patients rarely have symptoms. Incidence of rupture

approximates 20% with rupture-related mortality approaching 40%.147

Surgical management in cases of chronic celiac and SMA occlusion requires revascularization of at

least one vessel (most commonly the SMA) to minimize intestinal ischemia during IMA aneurysm

exclusion and theoretically decrease the risk of recurrent IMA aneurysm postoperatively. IMA aneurysm

ligation and/or excision may be sufficient for treatment in certain cases of robust collateral intestinal

circulation; in contrast certain cases will dictate IMA revascularization.150 The role for endovascular

therapy remains poorly defined.

RENAL ARTERY OCCLUSIVE AND ANEURYSMAL DISEASE

INTRODUCTION

Renovascular hypertension (RVH) is a well-defined form of secondary hypertension (HTN) that results

from renal arterial insufficiency at some level. The pathophysiology of such ischemia is broad, and with

both an increasing prevalence of atherosclerotic renal artery occlusive disease and ongoing clinical

trials, treatment standards remain in flux.

PATHOPHYSIOLOGY OF RENOVASCULAR HYPERTENSION

Renal artery stenosis resulting in a decrease in mean renal artery perfusion pressure by 10% to 15%

stimulates renin release from the kidney. Renin is a proteolytic enzyme produced by the

juxtaglomerular apparatus of the kidney that cleaves angiotensinogen to form angiotensin I. Angiotensin

I is further processed to angiotensin II by angiotensin-converting enzyme (ACE), which is produced in

the lung endothelium and vasculature (Fig. 91-21). Angiotensin II stimulates hepatic production of

renin, while providing a continuous negative feedback on the renal release of renin.151 Angiotensin II is

a potent vasopressor that increases arterial blood pressure by a variety of mechanisms (Fig. 91-22).

Glomerular filtration rate (GFR) is increased via vasoconstriction of the efferent arteriole. Additionally,

antidiuretic hormone (ADH) is released from the posterior pituitary gland, causing water conservation.

Release of aldosterone from the adrenal glands enhances exchange of sodium in the nephron-promoting

volume retention. Finally, angiotensin increases sympathetic tone. All of these mechanisms coalesce to

increase arterial pressure by way of arteriolar constriction, enhanced cardiac output, and the retention

of sodium and water. Renin has a half-life of 20 to 30 minutes and is primarily cleared by the liver.152

Normal physiology and sodium balance support a “steady state” of renin activity that is approximately

50% greater in the bilateral renal veins than that in the infrarenal inferior vena cava or peripheral

circulation. In cases of unilateral renal artery stenosis, HTN is characterized by renin hypersecretion

from the affected kidney and suppression of renin production in the contralateral kidney.153,154

Additionally, angiotensin-mediated vasoconstriction causes pressure diuresis of the unaffected kidney. In

cases of chronic bilateral or unilateral RVH in those patients with solitary kidney, sodium retention

accounts for late reductions in renin secretion.

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Figure 91-21. Renin–angiotensin system interrelation with aldosterone and bradykinin in blood pressure regulation. (Adapted

from Stanley JC, Graham LM, Whitehouse WM Jr. Renovascular hypertension. In: Miller TA, Rowland BJ, eds. Physiologic Basis of

Modern Surgical Care. St. Louis, MO: CV Mosby; 1988:734.)

Figure 91-22. Effects of angiotensins contributing to increased arterial pressure. (Adapted from Stanley JC, Graham LM.

Renovascular hypertension. In: Miller TA, ed. Physiologic Basis of Modern Surgical Care. 2nd ed. St. Louis, MO: Quality Medical

Publishing; 1998:918.)

RENAL ARTERY OCCLUSIVE DISEASE

7 Renal artery occlusive disease is the most common cause of correctable HTN in adults and the third

most common cause of HTN in children and should be considered in the clinical context of: (1)

childhood HTN, (2) severe HTN in women <45 years of age, (3) acute and rapid escalation of mild

HTN in older patients (>50 years), (4) initial diastolic BP >115 mm Hg, and (5) rapid deterioration in

renal function following the administration of antihypertensive therapy (especially with ACE

inhibition). Renovascular HTN can be notoriously resistant to traditional medical management. Clinical

examination may reveal an upper abdominal bruit during systole and diastole.

Diagnostic work-up should begin with serologies to assess renal function (BUN, creatinine) and

electrolyte levels. Additional blood hormone levels may help differentiate the diagnosis as high plasma

renin activity supports RVH while altered aldosterone, thyroid, and catecholamine levels may indicate

endocrine dysfunction. Urinalysis may reveal hematuria or azotemia concerning for intrinsic renal

disease. Ultrasonography is the first-line imaging modality for screening patients with RVH. While a

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high-quality duplex ultrasound examination in an experienced center is extremely accurate for the

diagnosis of main renal artery and ostial stenosis or occlusion, sensitivity is compromised when

surveying branch or parenchymal renal arteries and technically challenging in obese patients or in the

presence of abdominal gas.155 An elevated peak systolic velocity (>180 or >200 cm/s) or elevated

renal aortic ratio >3.5 (calculated by dividing the peak systolic velocity of the renal artery by the peak

systolic velocity of the adjacent aorta) detects renal artery stenosis with sensitivity and specificity of

84% and 97%, respectively.156 Ultrasonography additionally facilitates a determination of renal length

and symmetry, the presence of main renal artery aneurysm (RAA), visualization of adjacent structures

(i.e., obstruction, masses, aortic aneurysm), and the assessment of intrinsic vessel renovascular disease

by way of the resistive index.

Axial imaging with CTA and MRA are both useful adjunctive imaging modalities that better evaluate

stenosis, aneurysms, renal infarcts, dissections, and adjacent structures. These imaging modalities have

collectively received a class I indication (level B evidence) as screening tests to establish the diagnosis

of renal artery stenosis from the American College of Cardiology (ACC) and American Heart Association

(AHA).157 CTA offers excellent spatial resolution and generated three-dimensional multiplanar images

which can be very helpful in treatment planning. CTA however, is limited by the risk of contrastinduced nephropathy and in detecting subtle FMD lesions and branch vessel involvement. Multidetector

CTA offers sensitivity and specificity ranging from 86% to 93% and 90% to 100%, respectively.158 MRA

is often favored in younger patients as it offers diagnostic sensitivity and specificity of 97% and 93%

without the associated risks of irradiation.159 Gadolinium is less nephrotoxic than iodinated contrast and

while it may be advantageous for those patients with mild renal insufficiency, the risk of nephrogenic

systemic fibrosis prohibits the use of gadolinium contrast in those patients with a GFR ≤30

mL/min/1.73 m2. MRA offers the additional benefit of estimating renal perfusion and GFR via

calculations of gadolinium clearance.

Catheter-based arteriography remains the gold standard imaging modality for the diagnosis of renal

artery stenosis given its unmatched spatial resolution and capacity to detect reliably branch vessel and

parenchymal involvement. Additionally, pressure gradients can be measured across a stenosis (a systolic

pressure gradient <10 mm Hg is considered normal); intravascular ultrasound may be used to further

characterize the renal artery; and any clinically indicated therapeutic interventions can be performed in

the same clinical setting.

In cases of complex and equivocal disease, renal vein renin assessments may be used to calculate the

renal vein ratio. This ratio reflects a renin comparison between peripheral and renal venous blood. With

unilateral renal artery stenosis, the renal vein renin ratio (RVRR) is calculated by dividing the renin

activity in venous blood from the affected kidney by that from the (normal) contralateral kidney. A

ratio >1.48 supports a functionally relevant renal artery stenosis.153,154 In patients with bilateral renal

artery stenosis, a renal:systemic renin index (RSRI) is calculated by subtracting systemic renin activity

from individual renal vein renin activity and dividing the remainder by systemic renin activity; this

index reflects individual kidney renin release.153 As aforementioned, there is a steady state of normal

renal renin release; normal renal vein renin activity from each kidney is approximately 24% higher than

systemic activity (with the total of both kidneys being then 48% higher than systemic activity).

Documentation of renin hypersecretion (RSRI >0.48) associated with contralateral kidney renin

suppression (RSRI 0 to 0.24) provides a method to differentiate those patients that will be cured or

improved of RVH following renal revascularization or nephrectomy.153,160

Captopril scintigraphy (also known as isotopic or captopril renography) and hypertensive urography

have fallen out of favor and are no longer recommended as diagnostic studies for the diagnosis of renal

artery stenosis.

Arteriosclerosis

Arteriosclerosis is the most frequent cause of RVH affecting men twice as often as women, most

commonly in the sixth decade of life.161 Ostial stenosis is most common representing “spillover” of

diffuse aortic atherosclerosis, which is present in approximately 80% of patients. Arteriosclerotic renal

artery stenosis affects primarily the proximal third of the vessel, with more severe distal extrarenal

disease limited mainly to black patients.162 A contemporary prospective, multicenter, population-based

study of cardiovascular health has estimated the incidence of renovascular disease in men and woman

aged >65 years as 6% to 7%.161,163 Although early angiographic- and image-based studies in selected

patients with arteriosclerotic RVH have suggested radiographic progression in approximately a third of

renal artery lesions with 10% progressing to occlusion, this longitudinal cohort study reported anatomic

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progression to hemodynamically significant disease in only 4% of participants with an annualized

progression rate of 0.5% per year and no disease progression to arterial occlusion. Importantly,

renovascular disease has consistently been associated with cardiovascular disease across coronary,

cerebrovascular, mesenteric, and peripheral vascular beds with a significant and independent

relationship noted with prevalent coronary manifestations.164–168

Fibromuscular Dysplasia

FMD is thought to account for approximately 5% to 10% of RVH.169,170 FMD is a nonatherosclerotic,

noninflammatory vascular disease that may result in arterial stenosis, occlusion, aneurysm or dissection

that affects primarily younger women.171 The prevalence of FMD in the general population is unknown,

although renal involvement is the most common phenotype comprising 58% to 75% of all FMD

cases.172,173 FMD until recently has been described by histopathologic classification.174,175 By this

classification medial fibroplasia is the most common variant accounting for 60% to 90% of FMD cases.

Deposition in the media of loose collagen in zones of degenerating elastic fibrils results in the

generation of fibromuscular ridges with resultant arterial stenoses alternating with areas of smooth

muscle loss with consequent arterial dilation producing a classic “string of beads” appearance

angiographically (Fig. 91-23).172 The distal two-thirds of the main renal artery and its branches are most

commonly affected and bilateral disease is common. Intimal fibroplasia accounts for approximately 2%

to 5% of all dysplastic renal artery stenoses and presents as a smooth, focal stenosis of the distal main

renal artery. This histologic variant is notable for the accumulation of fibrous tissue within the intima

with a moderately cellular component with mainly intact or partially fragmented elastic lamina (Fig.

91-24). Perimedial fibroplasia and medial hyperplasia are uncommon variants.

Figure 91-23. A: Right renal arteriogram demonstrating a radiographically subtle focal midartery stenosis (arrow); manometry

across this lesion revealed a significant pressure gradient. B: Intimal fibroplasia as represented by pronounced intimal proliferation

and partial fragmentation of the elastic lamina (Movat stain, 20×).

Figure 91-24. Aortogram demonstrating a highly irregular perirenal aorta with (A) high-grade bilateral renal artery stenosis

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