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204 T. J. DiBartholomeo and J. Cynamon
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A
B
C
FIGURE 19-1. (A). Abdominal aorta and branches include the inferior phrenic arteries (IPA), celiac artery (CA), superior
mesenteric artery (SMA), right and left renal arteries (RRA, LRA), and inferior mesenteric artery (IMA). (B). Celiac artery (CA)
and branches include: common hepatic artery (CHA), splenic artery (SPL), left gastric artery (LGA), proper hepatic artery (PHA),
right hepatic artery (RHA), left hepatic artery (LHA), cystic artery (CYS), right gastric artery (RGA), gastroduodenal artery (GDA),
right gastroepiploic artery (RGE), and superior pancreaticoduodenal artery (SPD). Splenic branches include pancreatic (PC),
short gastric artery (SGA), and left gastroepiploic arteries (LGE). (C). Superior mesenteric artery (SMA) and branches include
inferior pancreaticoduodenal artery (IPD), jejunal branches (JB), ileal branches (IB), ileocolic artery (IC), right colic artery (RC),
middle colic artery (MC). Branches of the ileocolic artery include the appendicular artery (APA), ileal branch (IBr), and colic
branch (CBr). (D). Inferior mesenteric artery (IMA) and branches include left colic artery (LCA), sigmoid arteries (SIG), superior
rectal artery (SRA), and marginal artery of Drummond (MAD).
D
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typically a terminal branch of the SMA that continues the
inferior course of the vessel. The ileocolic typically arises at
a 45-degree angle from the main trunk of the SMA and
provides flow to the cecum and anastomotic branches to
the right colic. Ileal branches and the appendicular artery
arise from this vessel as well. The right colic artery arises
between the middle and ileo colic origins. Its branches
anastomose with both of these vessels. The right colic supplies the right colon and proximal transverse colon.
Inferior mesenteric artery (Fig. 19-1D)
The inferior mesenteric artery (IMA) arises from the left
anterolateral surface of the aorta, on the left at about the
L3 level. It supplies the distal transverse colon, left colon,
and sigmoid and superior rectum. The left colic is the first
branch, which divides into ascending and descending
branches. The ascending branch joins the left branch of
the middle colic to form the important arc of Riolan. This
anastomosis is important becausethere isa highincidence
of IMA origin occlusion in elderly patients. A similar anastomosis is the marginal artery of Drummond. This vessel
lies within bowel mesentery and is present along the mesenteric border of the large bowel. The marginal artery of
Drummond is formed bythe arcades of the ileocolic, right
colic, middle colic, and left colic branches. There are usually two or three sigmoid branches arising from the IMA.
The finalbranch of the IMA isthe superior hemorrhoidal,
which divides to supply both sides of the superior rectum.
The superior hemorrhoidal forms an important anastomotic network with middle hemorrhoidal branches. The
superior hemorrhoidal is a branch of the internal iliac,
and therefore these vascular systems are joined here.
arteries give off inferior adrenal branches, capsular
branches, branches to the renal pelvis, and proximal
ureter and gonadal arteries.
Lumbar arteries
There are typically five pairs of lumbar arteries. They
have a typical appearance as they initially have a cranial
route over the vertebral body pedicle and descend with
an ultimate posterolateral branching pattern. They arise
from the posterior aspect of the aorta. The last pair arise
just at the aortic bifurcation and can give off a middle
sacral branch.
Iliac arteries (Fig. 19-2)
The aorta bifurcates into common iliac arteries (CIA) at
the L4 or L5 level. The anatomic landmark is the umbilicus. The division is into common iliac arteries (CIA). The
CIAs can give rise to renal arteries in ectopic kidneys or
horseshoe kidneys. TheCIA divides into the internal (IIA)
and external (EIA) iliac arteries; another name for the IIA
is the hypogastric artery. The distal EIAs give off important
branches: the inferior epigastric and deep circumflex
iliac. The inferior epigastric forms ananastomosis with the
superior epigastric, whichis a branch of the internal mammary artery (see Chapter 13). The inferior epigastric is
recognizable because it has a truly cephalad and medial
course from the EIA. The deep circimflex iliac arises and
Renal arteries
The renal arteries originate just inferior to the SMA origin
at about the L1–2 level. The left renal artery orifice is typically lateral or slightly anterolateral in location, and the
right renal artery origin is positioned more anterolaterally.
There is variant renal artery anatomy in about one third of
individuals.About 70% of the populationhave singlerenal
arteries, and the remainder have multiple renal arteries or
an early bifurcation of the renal artery. The early bifurcation usually gives rise to an upper pole, the polar branch.
The remaining variations include two large renal arteries
on the same side, an upper-pole accesory vessel, a lowerpole accesory vessel, both an upper and lower pole vessel,
three renal arteries,or more than three vessels.
The renal artery divides into anterior and posterior
divisions at the renal hilus, which divide into lobar arteries. The lobar arteries divide into interlobar branches at
the level of the renal pyramids. The terminal branches
are the arcuate arteries, which are at the corticomedullary junction. In addition to the renal branches, the renal
FIGURE 19-2. Arteries of the pelvis include the right and left
common iliac arteries (RCIA, LCIA); each divide into an external iliac artery (REIA, LEIA) and an internal iliac artery (RIIA,
LIIA). Posterior internal iliac branches include superior gluteal
(SGA), iliolumbar (IL), and lateral sacral arteries (LS). Anterior
branches include obturator (OB), inferior gluteal (IG), and internal pudendal (IP). The middle sacral artery (MSA) arises as a
terminal branch of the aorta.
206 T. J. DiBartholomeo and J. Cynamon
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courses laterally and superiorly. These vessels mark the
boundary of the EIA and thecommon femoral artery.
Internal iliac artery
In most people, the internal iliac artery divides into two
main trunks: the posterior and anterior divisions. The
posterior division gives off the superior gluteal, iliolumbar, and lateral sacral branches. The anterior division
gives rise to the obturator, inferior gluteal, and internal
pudendal branches as well as smaller visceral branches.
The obturator artery terminates, as its name suggests, in
the obturator foramen. The inferior gluteal, in its course
to supply the gluteus muscle, gives off branches to the
sciatic nerve. The internal pudendal gives off the inferior
hemorrhoidal branch before giving rise to the penile
arteries, the dorsal artery of the penis, and the cavernosal
artery (also called deep). Visceral branches of the internal
iliac include the middle hemorrhoidal, branches to the
bladder (superior and inferior vesical arteries), and genital branches (prostate and seminal vesicles in men, the
uterine arteries in women).
■ Lower Extremity
3A). The profunda femoris varies in size. It courses lateral
and posteriorly, hence its other name is the deep femoral
artery. Less frequently, the profunda may arise immediately posteriorly or medial to the common femoral artery.
The medial and lateral femoral circumflex arteries most
commonly arise from the profunda femoris.
The superficial femoral artery (SFA) courses within the
medial thigh until it dives posteriorly at the level of the
adductor canal. This fenestration in the adductor magnus
muscle is also known as the Hunter’s canal. The canal is the
anatomic boundary of the SFA and popliteal artery. Near
the level of the adductor canal, the popliteal artery gives
off important branches: descending genicular, superior
genicular, and supreme geniculate. These are important
collateral vessels in popliteal arter y occlusive disease.
About two thirds of the popliteal artery is superior to the
knee joint; the remaining third is inferior. Inferior to
the knee joint inferior geniculate branches arise. The
popliteal artery demonstrates variation in its division.
Most frequently, there is division into the anterior tibial
artery and the tibioperoneal trunk (Fig. 19-3B). The anterior tibial artery courses anteriorly to perforate the in-
The anatomic boundary of the external iliac artery and
common femoral artery is the inguinal ligament. The
common femoral artery divides into the superficial femoral artery and the profunda femoris artery (Figure 19-
A
FIGURE 19-3. (A). The distal external iliac (EIA) becomes the common femoral (CFA) at the inguinal ligament, the superficial
femoral (SFA), deep femoral (PFA) and lateral femoral circumflex (LFC) arteries. Note also the relationship of the deep circumflex
iliac (DCIA) and the interior epigastric (IEA) arteries to the inguinal ligament (ILL). (B). Lower extremity arteries include superficial
femoral artery (SFA) popliteal artery (POP), superior and inferior geniculate arteries (SGA, IGA), tibial peroneal trunk (TPT),
anterior tibial artery (ATA), peroneal artery (PER), posterior tibial artery (PTA), dorsalis pedis artery (DP)
B
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terosseous membrane and continue inferiorly, overlying
the tibia to terminate as the dorsalis pedis artery in the
foot. The tibioperoneal trunk is a short vessel. The
peroneal artery has a medial course posterior to the interosseous membrane of the tibia and fibula. The
peroneal artery terminates with a posterior communicating branch andan anterior perforating branch. These can
act as important collaterals in the reconstitution of foot
vessels in tibial occlusive disease. The posterior tibial artery continues medially to pass posterior to the medial
malleolus. It then courses anteriorly and inferiorly as a
plantar branch. Together with branches of the dorsalis
pedis branch, a pedal arch is formed.
■ Venous Anatomy
Two important axioms that all medical students have
learned are that veins follow their respective arteries and
that veins var y. True to form, we will attempt to stay with
this teaching.
Inferior vena cava (Fig. 19-4)
The confluence of iliac veins forms the inferior vena cava
(IVC) at approximately the L5 level. It is a retroperitoneal structure that lies anterior and slightly to the right
of the spine. It courses through the liver along the posterior surface of the caudate lobe. It then has a short
segment between the liver and heart, where it pierces the
diaphragm. It drains into the posterior aspect of the
right atrium. Along its retroperitoneal course, it drains
lumbar branches, renal veins, right adrenal veins, and
hepatic veins. The caudate lobe of the liver drains directly into the intrahepatic segment of the IVC. Duplication of the IVC, left-sided IVC, or absence of the IVC
with azygos or hemiazygos continuation is seen in 0.5 to
2% of individuals.
Renal and adrenal veins (Fig. 19-5)
The right renal vein typically enters the IVC at approximately the L1 level. It is usually single; however, supranumerary right renal veins have been noted as well as drainage of adrenal and gonadal veins. The left renal vein is
single and anterior (preaortic) in about 80% of individuals. A circumaortic ring of veins is seen in about 20%, a
single retroaortic vein (posterior to aorta) in about 3%.
The left adrenal vein and gonadal vein typically drain
into the left renal vein. The right adrenal vein most
commonly drains directly into the IVC just superior to
the right renal vein insertion. Rarely, there can be drainage into a hepatic vein as well.
Hepatic and portal veins (Fig. 19-6A and B)
Typically, there are three hepatic veins: right, middle, and
left. The middle and left commonly form a single trunk,
and the right hepatic vein drains directly into the IVC. As
stated, the caudate lobe of the liver drains directly into
the IVC. This explains its frequently encountered “hypertrophy” noted in cirrhosis.
The portal vein runs in the hepatoduodenal ligament
FIGURE 19-4. Inferior vena cava (IVC). Major tributaries include bepatic vein (HV), left renal vein (LRV), right renal vein
(RRV), right and left common iliac veins (RCIV, LCIV).
FIGURE 19-5. Renal and adrenal veins. Right renal vein
(RRV), right gonadal vein (RGV) and right adrenal vein (RAD).
Left renal vein (LRV), left gonadal (LGV) and left adrenal vein
(LAV). Note the relationship of the aorta (AOR), the superior
mesenteric artery (SMA) and the inferior vena cava (IVC).
208 T. J. DiBartholomeo and J. Cynamon
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A
FIGURE 19-6. (A). Hepatic veins. Left (LHV), middle (MHV), and right (RHV). Veins from the caudate lobe of the liver (VCL)
drain separately into the inferior vena cava (IVC). (B). Portal venous system includes superior mesenteric vein (SMV), splenic
vein (SPL), inferior mesenteric vein (IMV), and gastrocoronary vein (GCV). Main portal vein (PV), right and left branches (RPV,
LPV), umbilical (UMB) and caudate (CB) branches of LPV are noted.
B
posterior to the common bile duct and the hepatic artery; however it is usually flanked by the common bile
duct to its right and the hepatic artery to its left. The
portal vein forms where the superior mesenteric vein and
splenic vein conjoin at approximately the L1–2 level. The
splenic vein has a horizontal course, posterior to the
pancreas, much less tortuous than the typical appearance
of the splenic artery. The inferior mesenteric vein drains
the IMA territory and empties into the splenic vein.
Within the hepatic parenchyma, the portal vein divides
into left and right branches. The left branch maintains its
A
FIGURE 19-7. (A). Pelvic veins include right external, common and internal iliac veins (REIV, RCIV, RIIV). Branches of the left
internal iliac vein shown: inferior hemorrhoidal (IHV), pudendal (PUD), inferior vesical (IVV), uterine (UTV), obturator (OBV)
veins. Note also sacral venous plexus (SVP), left lumbar and iliac lumbar veins (LUMV, LILUM), right ascending lumbar vein
(RALV), as well as inferior mesenteric vein (IMV) and inferior vena cava (IVC). (B). Veins of the lower extremity include the
superficial venous system, which includes the greater saphenous vein (GSV) and lesser saphenous (LSV). Deep venous system
includes paired anterior tibial, posterior tibial, and peroneal veins (TV), popliteal vein (PV), superficial femoral vein (SFV), and
profunda femoris veins (PFV).
B
Vascular Anatomy below the Diaphragm
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209
embryonic connections to the umbilical vein and ductus
venosus. Once obliterated, these are termed the ligamen-
tum teres and ligamentum venosum, respectively. These vessels can recannulate with portal hypertension. It is important to recognize that numerous gastric and pancreatic
veins are present, and these veins drain into the portal
vein; however these are frequently not seen in patients
with normal portal vein pressures. Their recognition is
vital in studies for portal hypertension.
Pelvis and lower extremity
The external iliac veins and common iliac veins are direct
conduits for the return of blood from the lower extremity
(Fig. 19-7A). The internal iliac (or hypogastric veins) are
conveniently divided into three components, as described by Kadir: (1) The veins arising external to the
pelvis, such as the gluteal veins (superior and inferior),
the pudendal veins (prostatic plexus in the male or
uterovaginal plexus in the female), and the obturator
veins, which typically follow their respective arteries;
(2) posterior pelvic veins, which arise from the sacral
venous plexus, and have important connections with the
paravertebral veins; and (3) the internal pelvic veins,
which drain the pelvic viscera, and are the hemorrhoidal,
vesicular, external pudendal, and uterine veins.
The veins of the lower extremity comprise both superfi-
cial and deep systems (Fig. 19-7B). The superficial system
is dominated by the greater saphenous vein, which arises
along the medial and anterior aspect of the foot. A deep
system arises at the popliteal vein, which is the confluence
of smaller leg veins. Like their so-named arteries, the superficial femoral vein starts at the adductor hiatus and
continues into the common femoral vein. These drain
directly into the external iliac veins, as described previously herein. The deep and superficial systems communicate via perforating veins. These veins contain valves
that direct flow toward the deep system. Failure of this
valve system can result in varicosities. Accessory saphenous veins aid in draining the thigh, and a lesser saphenous vein begins drainage of the lateral aspect of the foot
and ultimately empties into the deep system.
SUGGESTED READINGS
1. Abrams HL, Baum S, Pentecost MJ. Abrams’ Angiography: Vascular
and Interventional Radiology, 4th ed. Boston: Little, Brown; 1997.
2. Clemente C. Anatomy: A Regional Atlas of the Human Body. 2nd ed.
Baltimore: Urban & Schwarzenberg; 1981.
3. Kadir S. Diagnostic Angiography. Philadelphia: WB Saunders; 1986.
4. Kadir S. Atlas of Normal and Variant Angiographic Anatomy. Philadel-
phia: WB Saunders; 1991.
5. Moore KL. Clinically Oriented Anatomy. 2nd ed. Baltimore: Williams
& Wilkins; 1985.
6. Moore KL. The Developing Human: Clinically Oriented Embryology. 3rd
ed. Philadelphia: WB Saunders; 1982.
7. Strandness E, van Breda A. Vascular Diseases: Surgical and Inter ven-
tional Therapy. New York: Churchill Livingstone; 1994.
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C.W. Bakal and J. CynamonAtheroscleroticDisease of the Aorta, Pel vis, and Lower Extremities
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Atherosclerotic Disease of the Aorta,
20
■■■
Pelvis, and Lower Extremities
CURTIS W. BAKAL and JACOB CYNAMON
Diagnostic arteriography for atherosclerotic disease of
the aorta, pelvis, and lower extremities is performed after the decision to treat has been made. Clinical history
and noninvasive studies that precede the angiogram almost always can make the diagnosis of chronic
atherosclerotic occlusive disease and often will be able
to define the levels at which critical stenoses occur. The
purpose of the angiogram is to define specifically the
anatomy to plan interventional or surgical therapy. Multiple views are often necessary to define the anatomy
clearly (Fig. 20-1). Thus, a thorough knowledge of potential available therapies is important to obtain an adequate study.
Traditional vascular surgical techniques require that
three things be defined. The first is the status of the
“inflow,” that is, the arteries upstream of the target lesion. (Because atheroocclusive disease is almost always
infrarenal, the infrarenal aorta and the common iliac
and external iliac arteries serve as the inflow for the
infrainguinal arteries, as an example.) The second is the
status of the “outflow,” the vascular segment or segments
downstream of the occlusive lesion. (For example, for
popliteal occlusion at Hunter’s canal, the outflow is the
popliteal artery and trifurcation vessels.) These two vessel sets define where the proximal anastomosis and distal
anastomosis of a bypass graft are placed. The third parameter is the type of conduit, for example, autologous
vein versus polytetrafluoroethylene (PTFE). Synthetic
conduits are used exclusively in the aortoiliac distribution, whereas an autologous vein is much preferred for
bypass to the tibial and pedal vessels. For femoropop-
liteal bypass grafts, if vein is available, most vascular surgeons will use it, especially if the graft has to cross the
knee joint; otherwise, PTFE is used (surgical bypasses
are usually named by their proximal and distal anastomoses; see Table 20-1.)
■ Chronic Occlusive Disease
Arteriosclerosis obliterans
Arteriosclerosis is a chronic disease that is progressive
and usually symmetric. Patients present with gradual onset or worsening of symptoms. Most patients with arteriosclerosis obliterans present with claudication. Risk factors
for arteriosclerosis obliterans include advanced age, hypertension, smoking, diabetes, hypercholesterolemia,
hypertriglyceridemia, and male sex. In the United States,
the most commonly accepted categorization of chronic
limb ischemia is the Rutherford Criteria, which is listed
in Table 20-2.
Rutherford criteria
Category 0
Asymptomatic patients in this category include those with
occlusive disease and congenital variants. The dorsal
pedal pulse can be absent in about 12% of patients,
although the posterior tibial pulse is rarely absent in
normal patients. Asymmetric pulse decrement alone is
not an indication for intervention in chronic disease.
1
211
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A–C
FIGURE 20-1. (A). An arteriogram was performed to evaluate a failing left common femoral to peroneal artery vein graft. The
arrow
proximal portion of the graft is not seen secondary to the overlapping superficial femoral artery (
demonstrates severe narrowing of the proximal portion of the vein graft (
arrowhead
(
graft, flow and lumenal patency (arrow) are improved.
) is seen better; the left deep femoral artery is visualized (
curved arrow
straight arrow
). (C). After balloon angioplasty of the proximal
). The superficial femoral artery
). (B). An oblique view
Categories 1–3
Patients with intermittent claudication usually have singlesegment stenosis or occlusion (80% of cases). In these patients, the level of claudication usually develops distal to
the level ofstenosis. Claudication is a reproducible painor
soreness brought on by a defined amount of exercise and
relieved by rest. (The term is derived from (Latin “to
limp,” after the Roman Emperor Claudius, who limped
across Europe as his armies conquered the continent).
These patients usually should be treated conservatively.
Claudication must be differentiated from pseudoclaudication caused by spinal stenosis. Pseudoclaudication presents with variable onset relieved by a change in position
TABLE 20-1. Typical Surgical Procedures
Operation Indication
Aortoaortic bypass Abdominal aortic aneurysm, without iliac extension
Aortoiliac bypass Abdominal aortic aneurysm extending to common iliac arteries
Aorto bifemoral bypass Aortoiliac occlusive disease involving both iliac arteries
Femoral–femoral bypass Unilateral severe iliac disease ipsilateral to symptoms; needs intact donor iliac artery contralateral
(“cross-femoral” bypass) to symptomatic side
Axillofemoral bypass Used in high-risk patients with bilateral severe iliac disease; generally, axillary artery to femoral artery bypass
(ipsilateral side), combined with cross-femoral bypass
Femoropopliteal bypass Long-segment superficial femoral artery stenosis/occlusion; typically, common femoral artery serves as
proximal anastomosis
Femorotibial bypass Combined superficial femoral and popliteal artery stenosis/occlusion;
(“fem-distal” bypass) occlusive disease frequently extends into proximal/midtibial arteries
Profundaplasty Surgical revision of focal profunda femoris origin stenosis; often
done in conjunction with femoropopliteal bypass
Iliac endarterectomy Rarely used
and with normal peripheral pulses. Claudication and
pseudoclaudication can coexist. The prevalence of intermittent claudication increases with age and is present in
3% of the population under 60 years of age and in 20% of
the population older than 75 years of age. It is relatively
stable in 60% of patients, with 15% actually improving
with conservative therapysuch as exercise and cessation of
smoking. Twenty-five percent of claudicators progress to
critical ischemia. Amputation isdone inonly 5to 6%of patients within 10 years of presentation of peripheral vascular disease (PVD); the amputation rate is higher in smokers and diabetics. Intervention should be reserved for
patients with debilitating or lifestyle-limiting claudication
Atherosclerotic Disease of the Aorta, Pelvis, and Lower Extremities 213
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TABLE 20-2. Clinical Categories of Chronic Limb Ischemia
Grade Category Clinical Description Objective Criteria
0 0 Asymptomatic: no hemodynamically Normal treadmill or reactive hyperemia test
1 Mild claudication Completes treadmill exercise, AP after
I 2 Moderate claudication Between categories 1 and 3
II 3 Severe claudication Cannot complete standard treadmill exercise
a
II
a
III
AP, ankle pressure; PVR, pulse volume recording; TP, toe pressure; TM, transmetatarsal.
a
Grades II and III, categories 4, 5, and 6, are embraced by the term
b
Five minutes at 3 mph on 12% incline.
From Rutherford RB, Baker JD, Ernest C, et al. Recommended Standards for reports dealing with lower extremity ischemia: revised version.
1997;26:517–538. With permission.
4 Ischemic rest pain Resting AP ⬍ 40 mm Hg, flat or barely
5 Minor tissue loss: nonhealing ulcer, Resting AP ⬍ 60 mm Hg, ankle or metatarsal
6 Major tissue loss extending above Same as category 5
significant occlusive disease
exercise ⬎ 50 mm Hg but at least 20 mm Hg
lower than resting value
and AP after exercise ⬍ 50 mm Hg
pulsatile ankle or metatarsal PVR; TP ⬍ 30
mm Hg
focal gangrene with diffuse pedal PVR flat or barely pulsatile; TP ⬍ 40 mm Hg
ischemia
TM level, functional foot no longer
salvageable
chronic critical ischemia.
b
J Vasc Surg
and for patientswith critical ischemia. It is important to remember that claudication is a marker for coronary artery
disease, whichis prevalent in nearly all PVD patients.
Categories 4–6
Patients with critical ischemia have a threatened extremity that requires intervention. Diagnostic studies such
as angiography should be performed to plan treatment.
Percutaneous and surgical interventions generally are
directed at restoring continuous or “straight-line” flow
to the foot. The purpose of such inter vention is to maintain a functional foot and allow ambulation. Critically
ischemic patients usually have multilevel occlusive disease. Symptoms from perfusion deficit develop in the
end organ, that is, the skin of the foot. Ischemic rest
pain (category 4) usually develops in the forefoot because resting-limb blood flow is insufficient to meet basal metabolic demand, causing pain in the cutaneous
nerves. It is often nocturnal, aggravated by elevation and
relieved by dependency. Dependent rubor is characteristic.
Category 5 patients present with ischemic ulcers. The
lesions usually are located distally on the toes, but they
also may be noted on the malleoli or shins. They may
result from minor trauma that fails to heal secondary to
chronically inadequate circulation. In diabetics, peripheral neuropathy allows repeated minor trauma, for example, from ill fitting shoes, to persist without being noted
by the patient. Superimposed infection can put the limb
at risk; gangrene may develop. These patients need to be
treated aggressively. A limb with major tissue loss (category 6) does not have a salvageable foot; however, an
angiogram and intervention may be indicated to pre-
serve as much of the lower limb as possible because
amputation sites may not heal in the face of vascular
insufficiency.
Angiographic findings
Atherosclerotic plaque is usually irregular and eccentric
but may also be smooth and concentric (Fig. 20-2).
Plaques may be ulcerated. Rarely, they are weblike. Collateral development is the hallmark of chronic arterial
occlusive disease, developing over time (weeks to
months) (Fig. 20-3). Collateral arteries can partially compensate for occlusion of major vessels. Acute occlusion of
normal vessels generally yields rapid, profound, limbthreatening ischemia. This typically occurs with trauma
or arterial emboli in young patients. In patients with
underlying occlusive disease, chronic collaterals may reduce the effect of an acute occlusion. (Fig. 20-4).
PVD can occur in focal and diffuse patterns. A critical
stenosis can undergo in situ thrombosis and convert to
a total occlusion. A superior convex meniscus usually
marks the proximal edge of the thrombosis. The occurrence of acute in situ thrombosis may be marked by a
sudden increase in the level of symptoms, for example,
sudden progression from claudication to rest pain or by
new onset claudication. With time, there is retrograde
propagation to the nearest large collateral and organization of the thrombus by fibrin.
Arteriosclerosis obliterans is progressive and generally
symmetric (Fig. 20-5). Significant atherosclerosis of the
abdominal aorta is usually infrarenal. In adult patients,
the adductor canal is usually the site of earliest plaque. In
young patients with a smoking history who develop premature PVD, aortoiliac disease may be manifest first. The
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