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CHAPTER 12 Vascular Diseases and Hypertension
Fig. 12.4 CT angiogram of the descending thoracic aorta shows a large
penetrating aortic ulcer above the diaphragm (arrow). (Courtesy of Bart
Domatch, MD, Radiology Department, University of Texas Southwestern Medical Center, Dallas, Texas.)
treatment for Buerger’s disease is complete tobacco abstinence. The
prostacyclin analog iloprost constitutes adjunctive therapy to reduce
limb ischemia and improve wound healing.
Raynaud’s phenomenon is a vasospastic disease of the small arteries of mainly the fingers and toes. Primary (idiopathic) Raynaud’s phenomenon occurs in the absence of underlying disorders. Secondary
Raynaud’s phenomenon occurs in association with connective tissue
diseases (e.g., scleroderma, polymyositis, rheumatoid arthritis, systemic lupus erythematosus), as well as with repeated mild physical
trauma (e.g., use of jackhammers), certain drugs (e.g., antineoplastic
chemotherapeutic agents, interferon, monamine-reuptake inhibitors
such as tricyclic antidepressants, serotonin agonists), and Buerger’s
disease. Patients usually complain of recurrent episodes of digital
ischemia, with a characteristic white-blue-red color sequence. Pallor
is followed by cyanosis if ischemia is prolonged and then by erythema
(reactive hyperemia) when the episode resolves. Episodes are precipitated by cold temperature or emotional stress. Physical examination
can be entirely normal between attacks with normal radial, ulnar, and
pedal pulses. Some patients may have digital ulcers or thickening of fat
pad (sclerodactyly). Patients should be instructed to avoid cold temperatures and dress warmly. Calcium-channel blockers (CCBs) reduce
the frequency and severity of vasospastic episodes.
Giant-cell arteritis is an immune-mediated vasculitis predominantly involving medium-sized and large arteries such as the subclavian artery, axillary artery, and aorta of the older adult with a strong
male predominance. Approximately 40% of patients with giant-cell
arteritis also have polymyalgia rheumatica, a syndrome characterized
by severe stiffness and pain originating in the muscles of the shoulders
and pelvic girdle. Patients may exhibit headache from temporal arteritis, jaw claudication from ischemia of the masseter muscles, or visual
loss from involvement of the ophthalmic artery. Chest pain suggests
the coexistence of aortic aneurysm or dissection. Physical findings
include low-grade fever, scalp tenderness in the temporal area, pale
and edematous fundi, or a diastolic murmur of aortic regurgitation.
BP difference of more than 15 mm Hg between arms suggests subclavian artery stenosis. Laboratory findings include significantly elevated
C-reactive protein and Westergren sedimentation rate plus anemia.
The diagnosis is confirmed by histologic examination of the arterial
tissue (frequently from temporal artery biopsy), showing infiltration
143
of lymphocytes and macrophages (i.e., giant cells) in all layers of
the vascular wall. High-dose corticosteroids are highly effective and
should be initiated immediately when the diagnosis is suspected to
prevent potentially permanent blindness. To minimize complications from long-term corticosteroid administration, the steroid dose
should be tapered to find the lowest dose needed to suppress symptoms, which often wane. Every attempt should be made to discontinue corticosteroids over time, and treatment with methotrexate or
the interleukin-6 receptor antagonist tocilizumab may be used as steroid sparing agents.
Takayasu’s arteritis is an idiopathic granulomatous vasculitis of
the aorta, its main branches, and the pulmonary artery. This condition is particularly common in young women of Asian descent,
but it also occurs in non-Asian women and men. The inflammatory
process in the vascular wall can lead to stenosis and/or aneurysm
formation. Hypertension, as a result of renal artery stenosis or aortic
coarctation, is the most common manifestation and is present in as
many as 80% of affected individuals. Because the vascular involvement is so widespread, patients may have symptoms and signs of
coronary ischemia, congestive heart failure, stroke, vertebrobasilar
insufficiency, or intermittent claudication. Physical findings include
bruits over the subclavian arteries or aorta, as well as diminished
brachial pulses and thus a low brachial artery BP. The diagnosis is
based primarily on this clinical presentation. First-line treatment
is with corticosteroids. Other immunosuppressive agents such
as methotrexate or cyclophosphamide are often added to prevent
disease progression and relapse, and newer biologics such as antiTNF inhibitors (infliximab, etanercept) provide a viable alternative.
Immunosuppressive therapy does not cause regression of preexisting vascular stenoses or aneurysms. For this reason, percutaneous or
surgical revascularization is usually required.
Arteriovenous (AV) fistulas are abnormal vascular communications that shunt blood flow from the arterial system directly into
the venous system, bypassing the capillary beds that normally ensure
optimal tissue perfusion and nutrient exchange. AV fistulas may be
congenital, as in AV malformation (AVM), or acquired. The main
causes of acquired AV fistula are penetrating trauma (e.g., gunshot,
knife wound) and surgically created shunts for hemodialysis access.
Patients may exhibit a pulsatile mass, symptoms related to compression of an adjacent organ, or bleeding from spontaneous rupture of
an AVM. Systolic and diastolic bruits or thrills may be detectable over
the fistula or AVM. An AVM in skeletal muscle may lead to bone malformation or a pathologic fracture, whereas AVM in the brain may
result in neurologic deficits or seizures. High-output heart failure is
another complication from a large AVM or fistula. MR angiography,
CT angiography, or conventional angiography confirms the diagnosis.
Depending on the size and location of the AVM, treatment options
include surgical resection, transcatheter embolization, or pulse laser
irradiation. Patients with acquired AV fistulas from trauma usually
need surgical closure.
PULMONARY VASCULAR DISEASE
Pulmonary hypertension is characterized by elevated mean pulmonary
artery pressure (PAP) of greater than 20 mm Hg at rest. The many
causes of pulmonary hypertension are summarized in Table 12.3.
Patients with pulmonary hypertension not only have an elevated
pulmonary arterial pressure but also a low cardiac output, causing
symptoms of exertional dyspnea, fatigue, and syncope. Pulmonary
capillary wedge pressure is usually normal (≤15 mm Hg) except in
patients with pulmonary hypertension due to impaired left ventricular
systolic or diastolic function or left-sided valvular heart disease.
144 SECTION II Cardiovascular Disease
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TABLE 12.3 Classification of Pulmonary
Hypertension
Category 1: Pulmonary Arterial Hypertension (PAH)
Primary pulmonary hypertension (PPH) or idiopathic pulmonary hypertension
(IPAH):
Sporadic
Familial
PPH associated with:
Connective tissue disease
Congenital heart disease
Portal hypertension
Human immunodeficiency viral infection
Drugs and toxins: Anorexigens, cocaine, methamphetamine
Category 2: Pulmonary Venous Hypertension
Left ventricular heart failure
Left ventricular valvular heart disease
Category 3: Pulmonary Hypertension Associated With
Chronic Respiratory Disease or Hypoxemia
Chronic obstructive pulmonary disease
Obstructive sleep apnea
Category 4: Pulmonary Hypertension Associated With
Chronic Venous Thromboembolism
Left ventricular valvular heart disease
Category 5: Pulmonary Hypertension Due to Miscellaneous
Disorders Directly Affecting the Pulmonary Vasculature
Sarcoidosis, histiocytosis X, compression of pulmonary vessels (adenopathy,
tumor, fibrosing mediastinitis)
Pulmonary Arterial Hypertension
Pulmonary arterial hypertension (PAH) is caused by a combination
of pulmonary vasoconstriction, endothelial cell and/or smooth muscle proliferation, intimal fibrosis, and thrombosis in the pulmonary
capillaries and arterioles. PAH is either idiopathic (primary pulmonary hypertension [PPH]) or secondary to connective tissue disease,
congenital heart disease, portal hypertension, or human immunodeficiency viral (HIV) infection, as well as anorexigenic drugs or toxins.
Connective tissue diseases, particularly scleroderma, are the most
common secondary causes of PAH.
Patients with mild PAH can be asymptomatic, but patients with
more advanced disease complain of exertional dyspnea, chest pain, syncope, or presyncope. Orthopnea is an uncommon symptom associated
with PAH and more commonly identified in patients with pulmonary
hypertension from left-sided heart disease. Physical findings include
a left parasternal lift, loud pulmonary component of the second heart
sound, murmur of tricuspid or pulmonic regurgitation, hepatomegaly,
peripheral edema, or ascites. Associated ECG abnormalities indicate
right ventricular hypertrophy, right atrial enlargement, or right axis
deviation. Echocardiography provides important information about
the severity of the pulmonary hypertension (i.e., estimated pulmonary
artery pressure, right ventricular dimensions and function) and its
potential causes (e.g., left ventricular failure, valvular lesions, congenital heart disease with left-to-right shunts). Pulmonary function tests,
ventilation-perfusion (
night oximetry, autoantibody tests, HIV serology, and liver-function
tests also should be performed to determine other potential causes.
Right ventricular catheterization should be performed in all patients
˙
˙
) lung scans, polysomnography or over-
with suspected PAH. Under basal conditions in the catheterization
laboratory, an elevated mean pulmonary artery pressure exceeding 20
mm Hg, a pulmonary capillary wedge pressure below 15 mm Hg, and
a pulmonary vascular resistance exceeding 3 units confirm the diagnosis. Acute vasodilator drug challenge should be performed during right
ventricular catheterization to guide appropriate treatment.
Without treatment, the prognosis of PAH is poor with a median
survival of less than 3 years. Patients with high-risk features for
clinical deterioration or death, including poor functional capacity,
history of syncope, or right ventricular failure, should be treated
with intravenous epoprostenol (a prostacyclin analog) because of
its proven efficacy to improve exercise capacity and overall survival.
Other prostacyclin analogs such as beraprost, treprostinil, and iloprost or prostacyclin-receptor agonists such as selexipag are also
effective in reducing pulmonary artery pressure and improving exercise capacity. Other classes of medications approved for treatment
of PAH include drugs that target the endothelin pathway and nitric
oxide (NO) pathway. Currently available endothelin-receptor antagonists (ERAs) include bosentan, ambrisentan, macitentan. Drugs in
the NO pathway include soluble guanyl cyclase stimulators (riociguat), and phosphodiesterase (PDE)5 inhibitors (sildenafil, tadalafil).
Combination therapy of two to three drugs from different classes
improves exercise capacity when compared to monotherapy and
should be considered in patients with severe disease or those who
fail to improve with monotherapy. Oral calcium-channel blockers (CCBs) are indicated only for the small subset of patients with
mild-to-moderate symptoms who demonstrate significant reduction
in pulmonary pressure with acute CCB challenge (decrease in mean
PAP of at least 10 mm Hg to an absolute level of less than 40 mm Hg
without a decrease in cardiac output). Supplemental home oxygen is
indicated for all patients with hypoxemia. Travel to high elevations
exacerbates hypoxia, and relocation to sea level improves symptoms.
Oral anticoagulation should be considered for patients with PAH,
particularly in those with a chronic indwelling central venous catheter
for intravenous epoprostenol. Iron status should be monitored regularly to avoid iron deficiency anemia to prevent further deterioration
in functional capacity. Diuretics should be prescribed for patients
with peripheral edema or hepatic congestion. Lung transplantation is recommended only for patients in whom severe symptoms
occur despite intensive medical therapy.
VENOUS THROMBOEMBOLIC DISEASE
Venous thromboembolism (VTE) encompasses both deep vein thrombosis (DVT) and pulmonary embolism (PE). Among the adult United
States population, the overall combined annual incidence is as high
as 2 new cases per 1000 persons. The incidence of VTE is higher in
men than it is in women and higher in African Americans and white
individuals than it is in Asians and Hispanics. Over 150 years ago, Dr.
Rudolf Virchow recognized three predisposing factors: (1) endothelial
damage, (2) venous stasis, and (3) hypercoagulation (Virchow’s triad).
Endothelial damage is common with surgery or trauma, venous stasis is common with prolonged bedrest or immobilization (leg cast),
and hypercoagulation is more prevalent with cancer, oral estrogen use,
and pregnancy. Trousseau syndrome consists of migratory thrombophlebitis with noninfectious vegetations on the heart valves (marantic
endocarditis) typically in the setting of mucin-secreting adenocarcinoma. Dr. Trousseau, a pathologist, diagnosed his own pancreatic
carcinoma on the basis of the association that now bears his name.
Hypercoagulable states include hereditary diseases such as deficiencies
in antithrombin III, protein C, or protein S; mutation in factor V gene
(factor V Leiden) or factor II gene (prothrombin G20210A); as well as
CHAPTER 12 Vascular Diseases and Hypertension
145
hyperhomocysteinemia. However, a thorough search for identifiable
risk factors will come up negative in 25% to 50% of patients with VTE.
Deep Vein Thrombosis
Most DVT starts in the calf veins. Without treatment, 15% to 30% of
these clots propagate to the proximal calf veins. The risk of a subsequent PE is much higher with proximal DVT than with clots confined
to the distal calf vessels (40% to 50% versus 5% to 10%, respectively).
Involvement of the upper extremities is much less common, but subclavian and/or axillary vein thrombosis also can lead to PE in as many
as 30% of affected individuals. The same risk factors that cause lower
extremity DVT also cause upper extremity DVT. In addition, other
specific causes of upper extremity DVT include traumatic damage
of the vessel intima from heavy exertion such as rowing, wrestling,
or weight lifting (Paget-Schroetter syndrome), from extrinsic compression at the level of thoracic inlet (thoracic outlet obstruction), or
from insertion of central venous catheters or pacemakers. Pain and/
or swelling are the major complaints from patients with DVT; however, a large number of patients with DVT are asymptomatic, particularly if the DVT is restricted to the calf. Patients with upper-extremity
DVT can develop the superior vena caval syndrome of facial swelling,
blurred vision, and dyspnea. Thoracic outlet obstruction can compress
the brachial plexus leading to unilateral arm pain associated with hand
weakness. Physical examination frequently reveals tenderness, erythema, warmth, and swelling below the site of thrombosis. Pain with
dorsiflexion of the foot (Homan’s sign) may be present, but the low
sensitivity and the low specificity limit its usefulness in the diagnosis
of lower extremity DVT. A palpable tender cord, dilated superficial
veins, and low-grade fever occur in some patients. Upper extremity
DVT can cause brachial plexus tenderness in the supraclavicular fossa
and atrophic hand muscles. For patients with probable thoracic outlet
obstruction, several provocative tests should be performed. Adson test
is positive if the radial pulses weaken during inspiration and during
extension of the arm of the affected side while rotating the head to the
same side. Wright test is positive if the radial pulses become weaker
and painful symptoms are reproduced while abducting the shoulder of
the affected side with the humerus externally rotated.
The laboratory diagnosis of DVT includes measurement of
D-dimers, which are fibrin degradation products. D-dimer elevation
is a highly sensitive indicator of DVT that can be performed rapidly
in the emergency department. In a patient with low to intermediate
probability, a negative D-dimer test effectively excludes the diagnosis of DVT. However, the test is not specific and can be elevated in
many other conditions frequently encountered in hospitalized patients
(e.g., inflammation, recent surgery, malignancy). Duplex ultrasonography can be used to demonstrate the presence of a blood clot and/or
noncompressibility of the affected veins proximal to the site of occlusion. Duplex ultrasonography has greater sensitivity in detecting proximal DVT (90% to 100%) than distal DVT (40% to 90%) of the lower
extremities. With upper extremity DVT, acoustic shadowing of the
clavicle may obscure detection of thrombosis in subclavian vein segments. MR angiography is particularly helpful in making the diagnosis
of upper extremity DVT and pelvic vein thrombosis. Contrast venography is the conventional gold standard test, but it is invasive and
technically difficult in patients with edematous extremities. Therefore,
invasive venography should be reserved for patients in whom the clinical suggestion is high, despite negative or inconclusive results from
noninvasive imaging.
Patients with DVT should be treated initially with subcutaneous
low-molecular-weight heparin (LMWH), or subcutaneous selective
factor Xa inhibitor fondaparinux to prevent thrombus propagation and
to maintain the patency of venous collaterals. Oral administration of
factor Xa inhibitors, rivaroxaban or apixaban, may also be used in the
initial monotherapy without pretreatment with heparin. In contrast,
other direct anticoagulants such as dabigatran and edoxaban should be
started only after an initial parenteral heparin or fondaparinux therapy
for 3 to 5 days. Intravenous unfractionated heparin (UFH) should be
given to only selected patients with DVT, such as those with severe renal
failure (creatinine clearance of <30 mL/minute) in whom LMWH and
fondaparinux are contraindicated or those with hemodynamic instability who may require thrombolytic therapy or invasive intervention.
Intravenous UFH should be given as a bolus, followed by continuous
infusion to maintain an activated partial thromboplastin time of at
least 1.5 times the control value. LMWH and fondaparinux has a longer half-life than UFH and can be given once or twice daily with similar
efficacy. Oral anticoagulation should be initiated after the acute phase.
In general, direct anticoagulants (DOACs) including dabigatran, rivaroxaban, apixaban, and edoxaban are preferred over warfarin because
of lower risk of intracranial hemorrhage without compromising antithrombotic efficacy. If warfarin is chosen, it should be initiated without delay with an overlap period with LMWH, UFH, or fondaparinux
therapy and titrated until the international normalized ratio (INR)
reaches a value between 2 and 3. DOACs, however, have rapid onset of
action and should be started at the discontinuation of UFH, LMWH,
or fondaparinux without overlap period to avoid bleeding complication. After the acute phase, oral anticoagulants should be continued
for 3 months in most patients. Lifelong anticoagulation should be
considered in patients with unprovoked proximal DVT (either first
episode or recurrent event) as well as patients with cancer-associated
DVT with low to moderate bleeding risk. Furthermore, avoidance of
frequent clinic visits to monitor INR during the initial period of warfarin titration is another major advantage of DOACs. When DVT is confined to the calf, the risk of PE is lower than proximal DVT. Therefore,
anticoagulants should be started only in patients with severe symptoms
or those with high-risk features for clot expansion, such as elevated
D-dimer, large thrombus with greater than 5 cm in length, multiple
vein involvement, history of thromboembolic events or active cancer, unprovoked DVT, or inpatient status. Oral anticoagulants should
be continued for 3 months in most patients. In the absence of severe
symptoms or risk factors for clot extension, patients with isolated distal DVT should be treated conservatively without anticoagulation with
close monitoring via serial imaging of the deep veins for 2 weeks.
When upper extremity DVT occurs in the subclavian veins or
axillary veins in patients who are severely symptomatic but otherwise healthy with low risk of bleeding, catheter-directed thrombolysis
should be considered as it carries lower risk of bleeding than systemic
thrombolytic therapy. The purpose of thrombolysis is to prevent or
minimize the post-thrombotic syndrome, which includes chronic
arm pain, swelling, hyperpigmentation, and ulceration from residual
venous obstruction. In asymptomatic patients with occlusion in the
more distal location, anticoagulation is preferred. If anticoagulation is
stopped prematurely for any reason, aspirin should be considered in
the absence of contraindication as it has been shown to reduce recurrent venous thromboembolism by 20% to 40% without increased risk
of bleeding.
Catheter-based direct thrombolysis is effective in restoring venous
patency and reducing post-thrombotic syndrome of venous congestion but increases risk of bleeding. Therefore, it should be considered
for patients with iliofemoral DVT of recent onset who have low risk of
bleeding. Vena cava filters are effective in reducing the incidence of PE,
but they increase the risk of recurrent DVT. Consequently, IVC filters
should be removed after 3 months. In patients treated with anticoagulation, addition of an IVC filter to anticoagulation offers no additional
benefit in reducing recurrent venous thromboembolism compared
146 SECTION II Cardiovascular Disease
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to anticoagulation alone. Therefore, it should be considered only in
patients in whom anticoagulation is contraindicated.
Pulmonary Embolism
PE occurs when a thrombus dislodges from the deep veins of the upper
or lower extremities. Pulmonary vascular resistance and pulmonary
arterial pressure increase from two mechanisms: (1) anatomic reduction
in cross-sectional area of the pulmonary vascular bed and (2) functional
hypoxia-induced pulmonary vasoconstriction. The pressure overload
on the right ventricle can lead to dilation, hypokinesis, and tricuspid
regurgitation. When severe, elevated right ventricular end-diastolic
pressure can compress the right coronary artery, causing subendocardial
ischemia. In acute PE, areas of lung tissue are ventilated but underperfused. This
blood flow from the obstructed pulmonary artery to other lung regions
with lower
foramen ovale, hypoxemia worsens when the sudden elevation in right
atrial pressure causes right-to-left shunting across the foramen.
The classic symptoms of acute PE are the sudden onset of dyspnea
and pleuritic chest pain. Additional symptoms include anginal chest
pain from right ventricular ischemia, hemoptysis from pulmonary
infarction, and syncope or presyncope from massive PE with acute
right ventricular failure (cor pulmonale). The most common physical
findings are tachypnea and tachycardia. Additional physical findings
include a right ventricular lift, inspiratory crackles, a loud pulmonary
component of the second sound, expiratory wheezing, and a pleural
rub. Symptoms and signs of proximal DVT are present in 10% to
20% of patients. Arterial blood gas analysis often reveals hypoxemia,
respiratory alkalosis, and a high alveolar-to-arterial oxygen tension
gradient. However, normal arterial blood gases values do not exclude
the diagnosis. The most common finding with ECG analysis is sinus
tachycardia. Atrial fibrillation, premature atrial contraction, and
supraventricular tachycardia are less common. Other ECG changes
suggest acute right ventricular strain. These include the S1-Q3-T3
pattern, a new right bundle branch block or right-axis deviation, and
P-wave pulmonale. However, these findings are present in only 30%
of patients with even massive PE. Common but nonspecific abnormalities with chest radiographic studies include atelectasis, pleural
effusion, and pulmonary infiltrates. Less common but more specific
radiographic findings include Hampton’s hump (i.e., wedge-shaped
infiltrate in the peripheral lung field), which is indicative of pulmonary
infarction and Westermark’s sign (decreased vascularity). The plasma
D-dimer test is elevated in most patients with PE as a result of activation of the endogenous fibrinolytic system, which is not sufficient to
dissolve the clot. Commercially available D-dimer assays have a high
sensitivity and negative predictive value but low specificity, particularly with increasing age. Therefore, it is important to use age-adjusted
cut-off values (age × 10 μg/L) in patients older than 50 years old to
improve specificity without compromising sensitivity of detection to
above 97%. A normal age-adjusted D-dimer test effectively excludes
the diagnosis of PE in patients in whom the clinical suggestion is low
or intermediate. However, it should not be used to screen patients
with high index of suspicion because of low negative predictive value.
Elevated levels of cardiac troponin I and troponin T and other markers
of myocardial injury can be found in patients with PE and are indicative of right ventricular dysfunction and a poor prognosis. Similarly,
elevated natriuretic peptides, including B-type natriuretic peptide
(BNP) and N-terminal pro-BNP have been shown to be predictive of
adverse outcomes.
CT angiography is the imaging modality of choice in patients with
suspected PE and high clinical probability because of its excellent visualization of the pulmonary artery (Fig. 12.5). The resolution of 1 mm
˙
˙
mismatch and the resultant redistribution of pulmonary
˙
˙
ratios cause arterial hypoxemia. In patients with a patent
Fig. 12.5 Spiral chest CT angiogram shows a large thrombus in the
right main pulmonary artery (arrow). (Courtesy of Michael Landay, MD,
Department of Radiology, University of Texas Southwestern Medical
Center, Dallas, Texas.)
or less rivals that of conventional invasive angiography. The speed of
the newer generation of scanners allows acquisition of all images within
a single breath-hold, avoiding respiratory motion artifacts. The overall negative predictive value of multidetector CT angiography exceeds
99%. A negative CT excludes the diagnosis of PE and eliminates the
need for further diagnostic testing. The CT scan also permits detection
of other pathologic conditions involving the lung parenchyma, pleura,
and mediastinal structures. Such pathologic findings may mimic
PE and constitute alternative causes of chest pain and dyspnea. The
requirement for intravenous injection of iodinated contrast material
restricts applicability to those without a history of kidney disease or an
allergic reaction to contrast dye. In such patients,
suitable imaging modality. A completely normal
excludes the diagnosis without further testing. However, less than
10% of
in whom a moderate or high level of clinical probability of PE exists, a
high-probability
however, a low or intermediate probability scan is no more helpful
than a coin flip. Fig. 12.6 presents an algorithm for the work-up of
PE based on current evidence. Echocardiography may directly detect
thrombi in the right atrium, right ventricle, or pulmonary artery or
indirectly demonstrate right ventricular dysfunction, signifying presence of hemodynamically significant emboli. Therefore, it is helpful in
diagnosis of PE in patients with hypotension or shock. Invasive pulmonary angiography should be reserved for patients in whom noninvasive
testing is inconclusive.
made to guide treatment approach. Patients with low risk based on
stable hemodynamic parameters without history of cardiovascular
disease or excessive bleeding risk for anticoagulation treatment may
be suitable for outpatient treatment or a brief inpatient observation.
Similar to the treatment of DVT described previously, oral direct anticoagulants with or without initial parenteral therapy are preferred over
warfarin because of lower risk of intracranial bleeding and increased
ease of use associated with DOACs. PE patients with moderate to high
risk features for cardiovascular decompensation (Table 12.4) should
be admitted and monitored closely (PESI class III-V, or simplified
PESI of at least 1). Aggressive parenteral therapy is preferred when
patients have one or more features of high clinical risk. Thrombolytic
therapy with recombinant tissue plasminogen activator (rt-PA) is indicated for patients with hypotension or shock. In patients with right
˙
˙
scans are interpreted as definitively normal. In patients
˙
˙
scan has a diagnostic accuracy of 90% to 100%;
Once diagnosis of PE is made, clinical risk assessment should be
˙
˙
scan is a more
˙
˙
scan effectively
Outpatients/ ER patients
Pretest probability
Inpatient
CHAPTER 12 Vascular Diseases and Hypertension
147
Low
D-dimer
Normal Elevated
No PE
Fig. 12.6 Diagnostic algorithm for patients with suggested pulmonary embolism (PE).
Moderate-to-high
Renal failure, contrast allergy, or pregnancy ?
Spiral chest
CT angiography
No PE PE
TABLE 12.4 Pulmonary Embolism Severity
Index (PESI)
Parameter OriginalaSimplified
Age Years 1 (for age >80
yrs)
Male sex +10 —
Cancer +30 1
Chronic heart failure +10 1
Chronic pulmonary disease +10
HR at least 110 bpm +20 1
SBP <100 mm Hg +30 1
Respiratory rate >30 breaths per min +20 —
Temperature <36° C +20 —
Altered mental status +60 —
Arterial oxyhemoglobin saturation <90% +20 1
a
Original: Total Score Class
≤65: I
66-85: II
86-105: III
106-125: IV
>125: V
Simplified:
0= low risk
≥1 = high risk
ventricular enlargement or dysfunction alone without hypotension
(known as submassive PE), thrombolytic therapy reduces the risk of
hemodynamic decompensation at the cost of increased risk of major
hemorrhage and stroke. Thus, anticoagulation alone is preferred in
most cases of submassive PE. After initial treatment with heparins or
fondaparinux in high-risk patients, DOACs should be administered in
a similar manner to treatment of DVT. If warfarin therapy is chosen
instead of DOACs, parenteral anticoagulation should be administered
until a therapeutic INR of 2 to 3 is reached. Surgical or percutaneous
a
Ye sNo
˙
˙
V/Q scan
Normal
No PE
Low or intermediate
probability
Ultrasonography of
lower extremities +/–
pulmonary angiography
in selected patients
High
PE
removal of emboli should be considered in patients with massive PE
who have contraindications for thrombolytic therapy.
The time necessary to continue anticoagulation after an acute PE
or DVT episode depends on the presence or absence of reversible risk
factors for recurrent VTE. Patients with a history of trauma or surgery
generally have a low rate of recurrent VTE; therefore, warfarin can be
discontinued after 3 months of administration. Patients with cancer
and VTE should be treated initially with subcutaneous fixed-dose
LMWH for 3 to 6 months because of its greater efficacy than warfarin
in preventing recurrent thromboembolism in this setting. Preliminary
studies indicated that DOACs are as effective as LMWH in preventing thromboembolic events though the bleeding risk is higher with
DOACs. After this initial period, treatment with LMWH or DOACs
should be continued indefinitely unless the cancer is cured. Patients
with unprovoked PE with low risk of bleeding should be treated with
oral anticoagulation for more than 3 months while those with high
bleeding risk should be on treatment for at least 3 months. Beyond 3
months, aspirin is an alternative to long-term warfarin and should be
considered for patients who have contraindication for anticoagulation
or high bleeding risk.
Venous Thromboembolism Prophylaxis
Patients who are at high risk for VTE should receive pharmacologic
prophylaxis. Subcutaneous LMWH is generally preferred over subcutaneous UFH because of a modest reduction in venous thromboembolism in high-risk patients. UFH is usually reserved for patients with
creatinine clearance less than 30 mL/min). Patients at high risk include
those who are hospitalized with acute medical illness—particularly congestive heart failure, acute respiratory illness, acute inflammatory diseases—those who are expected to be immobilized for 3 days or longer, or
patients with previous VTE. Major surgery, either elective or emergent,
is an important indication for VTE prophylaxis. Subcutaneous LMWH
has a marginal advantage over UFH in preventing symptomatic DVT
in patients undergoing general surgery, gynecologic surgery, or neurosurgery in some but not all studies. However, LMWH is more effective
148 SECTION II Cardiovascular Disease
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than UFH and adjusted dose warfarin (INR between 2-3) and is preferred for prevention of DVT in orthopedic surgery such as hip surgery
or total knee replacement because of superior efficacy (level of evidence
A). DOACs, such as dabigatran, rivaroxaban, and apixaban, have similar efficacy and safety when compared with LMWH in preventing VTE
after knee surgery without increasing perioperative bleeding. Efficacy of
DOACs in preventing VTE after hip surgery relative to LMWH has not
been directly tested in the randomized trials. DVT prophylaxis should be
continued for 10 to 14 days after knee surgery and 35 days after hip surgery. Patients undergoing major cancer surgery should receive continued prophylaxis after discharge up to 28 days. Mechanical prophylaxis
with intermittent pneumatic compression has not been shown to confer
additional benefit in preventing VTE in medical, surgical, and trauma
ICU patients when used in combination with pharmacologic thromboprophylaxis versus pharmacologic thromboprophylaxis alone. However,
it should be considered in patients with high risk of bleeding in whom
anticoagulation is contraindicated.
ARTERIAL HYPERTENSION
Arterial hypertension is the leading cause of death in the world,
affecting 103 million adults in the United States and 1.4 billion people worldwide. It is the most common cause for an outpatient visit
to a physician and the most easily recognized treatable risk factor for
stroke, myocardial infarction, heart failure, peripheral vascular disease, aortic dissection, atrial fibrillation, and end-stage kidney disease.
Despite this knowledge and unequivocal scientific proof that treating
hypertension with medication dramatically reduces its attendant morbidity and mortality, hypertension remains untreated or undertreated
in the majority of affected individuals in all countries, including those
with the most advanced systems of medical care. The 2017 American
Heart Association/American College of Cardiology guideline has
introduced the new threshold for diagnosis and treatment of hypertension to less than 130/80 mm Hg while most other countries in the
world have continued the old thresholds of less than 140/90 mm Hg
in their guidelines. Fewer than one in two Americans with hypertension have their blood pressure treated and controlled to below the new
130/80 mm Hg guideline. Globally, hypertension control rates among
treated individuals have plateaued at the range below 70% since the
mid-2000s (Fig 12.7). Thus, hypertension remains one of the world’s
great public health problems. The asymptomatic nature of the condition impedes early detection, which requires regular BP measurement. Because most cases of hypertension cannot be cured, BP control
requires lifelong treatment with prescription medications, which can
be costly. Effective hypertension management requires continuity of
care by a regular and knowledgeable medical provider, as well as sustained active participation by an educated patient. This section reviews
the most important principles in the early detection and effective treatment of hypertension.
Initial Evaluation for Hypertension
The initial evaluation for hypertension needs to accomplish three
goals: (1) staging of BP, (2) assessing the patient’s overall cardiovascular risk, and (3) detecting clues of secondary hypertension. The initial
clinical data needed to accomplish these goals are obtained through
a thorough history and physical examination, routine blood tests, a
spot (preferably first morning) urine specimen, and a resting 12-lead
ECG. Home BP monitoring is indicated in most patients to confirm
the diagnosis of hypertension and to exclude white coat syndrome. In
most cases, home BP or 24-hour ambulatory BP monitoring provides
helpful additional data about the time-integral burden of BP on the
cardiovascular system.
Goal 1: Accurate Assessment of Blood Pressure
Across populations, the risks of heart disease and stroke increase continuously and logarithmically with increasing levels of systolic and
diastolic BPs at or above 115/75 mm Hg (Fig. 12.8). Thus, the dichotomous separation of normal from high BP is artificial. BP is currently
staged as normal, elevated, or hypertension based on the average of
two or more readings taken on at least two separate occasions. When
a patient’s average systolic and diastolic pressures fall into different
stages, the higher stage applies (Table 12.5). Elevated BP is designated
as BP in the 120 to 129 mm Hg systolic in the presence of diastolic BP
below 80 mm Hg. Individuals with elevated BP are at higher risk for
progression into hypertension and cardiovascular events.
BP normally varies dramatically throughout a 24-hour period.
To minimize variability in readings, BP should be measured at least
twice after 5 minutes of rest with the patient seated, the back supported, and the arm bare and at heart level. The most common mistake in measuring BP is using a standard-issue cuff that is too small
for a large arm, producing spuriously elevated readings. Most overweight adults will require a large adult cuff. Tobacco and caffeine
should be avoided for at least 30 minutes. To avoid underestimation of systolic pressure in older adults who may have an ausculta-
tory gap as a result of arteriosclerosis, radial artery palpation should
be performed to estimate systolic pressure; then the cuff should be
inflated to a value 20 mm Hg higher than the level that obliterates
the radial pulse and deflated at a rate of 3 to 5 mm Hg per second.
BP should be measured in both arms and after 5 minutes of standing, the latter to exclude a significant postural fall in BP, particularly in older persons and in those with diabetes or other conditions
(e.g., Parkinson’s disease) that predispose the patient to autonomic
insufficiency.
However, out-of-office readings either with home or ambulatory
BP monitoring are required to accurately assess a person’s typical BP.
Because of the anxiety of going to the physician, BPs often are higher in
the physician’s office than when measured at home or during normal
daily life outside the home. Self-monitoring of BP outside of the physician’s office actively engages a patient in his or her own health care and
provides a better estimate of a person’s usual BP for medical decision
making. BP should be measured in early morning and evening times.
Three BP readings should be obtained during each measurement, separated by at least 1 minute. Because the first BP tends to be the highest, average BP should be used to assess home BP. Many electronic
home monitors are available, but only a handful of models have been
rigorously validated against mercury sphygmomanometry and can be
recommended.
Ambulatory monitoring provides automated measurements of BP
over a 24- or 48-hour period while patients are engaged in their usual
activities, including sleep (Fig. 12.9). The normal limits of 24-hour
ambulatory BP, which are corresponding to office BP of 130/80 mm
Hg, are a mean daytime BP of less than 130/80 mm Hg, mean nighttime BP of 110/65 mm Hg, and a mean 24-hour BP of less than 125/75
mm Hg. To avoid undertreating hypertension, these lower treatment
thresholds must be used when incorporating ambulatory monitoring
in medical decision making. With self-monitoring of BP at home, an
average value of less than 130/80 mm Hg should be considered the
upper limit of normal.
Up to one third of patients with elevated office BPs have normal
home or ambulatory BPs. If the 24-hour BP profile is completely normal and no target organ damage has occurred despite consistently
elevated office readings, then the patient has office only, or white
coat, hypertension, presumably the result of a transient adrenergic
response to the measurement of BP in the physician’s office (see Fig.
12.9). In other patients, office readings underestimate ambulatory BP,
CHAPTER 12 Vascular Diseases and Hypertension
Proportion of treated participants
Proportion of treated participants
Proportion of treated participants
Proportion of treated participants
Women
Men
Australia Canada Finland Germany Ireland Italy JapanNew Zealand South Korea Spain UK USA
149
100
75
50
25
0
with hypertension, controlled (%)
100
75
50
25
0
with hypertension, controlled (%)
100
75
50
40–49 years
50–59 years
60–69 years
40–49 years
50–59 years
60–69 years
25
0
with hypertension, controlled (%)
100
75
50
25
0
with hypertension, controlled (%)
presumably because of sympathetic overactivity in daily life owing to
job or home stress, tobacco use, or other adrenergic stimulation that
dissipates when coming to the office (Fig. 12.10). Such documentation
prevents underdiagnosing and undertreating this masked hypertension,
which is also associated with high cardiovascular risks and identified in
10% of hypertensive patients in general, up to 40% of those with diabetes, and 70% of African American patients with hypertensive kidney
disease.
70–79 years
1980 1990 2000 2010
Year
Fig. 12.7 Trends in hypertension control rates in 12 high-income countries. (NCD Risk Factor Collaboration
[NCD-RisC], Lancet July 2019;10199:639-651.)
1980 1990 2000 2010
70–79 years
Year
(atherosclerotic cardiovascular disease) among patients without
history of cardiovascular disease in hypertensive patients. Patients
with 10-year ASCVD risk of 10% or higher with BP of at least
130/80 mm Hg should be started on antihypertensive drug treatment without delay. In addition to ASCVD risk, presence of target
organ involvement, such as left ventricular hypertrophy or proteinuria, which are not captured by PCEs but should be considered as
a high-risk feature.
Goal 2: Cardiovascular Risk Stratification
The great majority of patients with BPs in the prehypertensive or
hypertensive range will have one or more additional modifiable
risk factors for atherosclerosis (e.g., hypercholesterolemia, cigarette smoking, diabetes). The Pooled Cohort Equations (PCEs)
is now recommended to estimate the 10-year risk of ASCVD
Goal 3: Identification of Secondary (Identifiable) Causes
of Hypertension
A thorough search for secondary causes is not cost-effective in most
patients with hypertension, but it becomes critically important in
two circumstances: (1) when a compelling cause is found on the initial evaluation, or (2) when the hypertensive process is so severe that
150 SECTION II Cardiovascular Disease
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Coronary disease
mortality
Age at risk
256
128
64
32
16
8
0
2
Floating absolute risk and 95% CI
1
0
120 140 160
Usual systolic BP, mm Hg
Fig. 12.8 Age-specific relevance of usual blood pressure to vascular mortality. Increased risk of myocardial
infarction and stroke was observed with increasing levels of systolic BP beginning at the level of 115 mm Hg.
(From Lewington S, et al. Age-specific relevance of usual blood pressure to vascular mortality: A meta-analysis of individual data for one million adults in 61 prospective studies. The Lancet 2002:360:1903-1913.)
TABLE 12.5 Staging of Office Blood Pressure
Blood Pressure
Category
Normal <120 and <80
Elevated 120-129 and <80
Stage 1 hypertension 130-139 or 80-89
Stage 2 hypertension ≥140 or ≥90
a
Calculation of seated blood pressure is based on the mean of two or
more readings on at least two separate occasions.
From Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/
AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for
the prevention, detection, evaluation, and management of high blood
pressure in adults: a report of the American College of Cardiology/
American Heart Association Task Force on Clinical Practice Guidelines.
Systolic Blood
Pressure (mm Hg)
Diastolic Blood
Pressure (mm Hg)
80–89 yr
70–79 yr
60–69 yr
50–59 yr
40–49 yr
180
a
it either is refractory to intensive multiple-drug therapy or requires
hospitalization. Table 12.6 summarizes the major causes of secondary
hypertension that should be suggested on the basis of a good history,
physical, and routine laboratory tests.
Renal Parenchymal Hypertension
Chronic kidney disease is the most common cause of secondary hypertension. Hypertension is present in more than 85% of
patients with chronic kidney disease and is a major factor causing their increased cardiovascular morbidity and mortality. The
mechanisms causing the hypertension include an expanded plasma
volume and peripheral vasoconstriction, with the latter caused by
both activation of vasoconstrictor pathways (renin-angiotensin
and sympathetic nervous systems) and inhibition of vasodilator
pathways (nitric oxide). Renal insufficiency should be considered
when microalbuminuria of more than 30 mg/gram of creatinine is
present or when the estimated glomerular filtration rate (eGFR) is
below 60 mL/min/1.73 m2.
Stroke
mortality
256
128
64
32
16
8
0
2
Floating absolute risk and 95% CI
1
0
120 140 160
Usual systolic BP, mm Hg
Age at risk
80–89 yr
70–79 yr
60–69 yr
50–59 yr
180
Renovascular Hypertension
Unilateral or bilateral renal artery stenosis is present in less than 2% of
patients with hypertension in a general medical practice but up to 30% in
patients with medically refractory hypertension. The main causes of renal
artery stenosis are atherosclerosis (85% of patients), typically in older
adults with other clinical manifestations of systemic atherosclerosis and
fibromuscular dysplasia (15% of patients), typically in women between the
ages of 15 and 50 years. Unilateral renal artery stenosis leads to underperfusion of the juxtaglomerular cells, thereby producing renin-dependent
hypertension even though the contralateral kidney is able to maintain normal blood volume. In contrast, bilateral renal artery stenosis (or unilateral
stenosis with a solitary kidney) constitutes a potentially reversible cause
of progressive renal failure and volume-dependent hypertension. The
following clinical clues increase the suggestion of renovascular hypertension: any hospitalization for urgent or emergent hypertension; recurrent
flash pulmonary edema; recent worsening of long-standing, previously
well-controlled hypertension; severe hypertension in a young adult or in
an adult after 50 years of age; precipitously and progressively worsening of
renal function in response to angiotensin-converting enzyme (ACE) inhibition or angiotensin II-receptor blockade (ARB); unilateral small kidney
by any radiographic study; extensive peripheral arteriosclerosis; or a flank
bruit. The diagnosis is confirmed by noninvasive testing with MR or spiral computed tomographic (CT) angiography (Fig. 12.11). Renal artery
angioplasty often cures fibromuscular dysplasia. Atherosclerotic renal
artery stenosis should be treated with intensive medical management of
atherosclerotic risk factors (hypertension, lipids, smoking cessation).
Revascularization should be considered for the following indications: (1)
medically refractory hypertension, (2) progressive renal failure on medical therapy, and (3) bilateral renal artery stenosis or stenosis of a solitary
functioning kidney.
Primary Aldosteronism
The most common causes of primary aldosteronism are (1) a unilateral
aldosterone-producing adenoma and (2) bilateral adrenal hyperplasia.
Because aldosterone is the principal ligand for the mineralocorticoid
CHAPTER 12 Vascular Diseases and Hypertension
151
250
200
150
100
BP mm Hg
50
0
16:00
Fig. 12.9 Twenty-four hour ambulatory blood pressure (BP) monitor tracings in two different patients. (A)
Optimal blood pressure (BP) in a healthy 37-year-old woman. The normal variability in BP, the nocturnal dip
in BP during sleep, and the sharp increase in BP on awakening are noted. (B) Pronounced white coat effect
in an 80-year-old woman referred for evaluation of medically refractory hypertension. Documentation of the
white coat effect prevented overtreatment of the patient’s isolated systolic hypertension.
250
Office
BP
200
150
100
BP mm Hg
50
0
11:00
Fig. 12.10 Twenty-four hour ambulatory blood pressure (BP) monitor
tracing shows both masked hypertension and nocturnal hypertension in
a 55-year-old man with stage 3 chronic kidney disease. Treatment with
three different antihypertensive medications in this patient produced
an office BP of 125/75 mm Hg, which seems to be at goal. However,
progressive hypertensive heart disease and deterioration of renal function suggested masked hypertension. Ambulatory monitoring revealed
that the patient’s treated BP was much higher out of the office, documenting both masked hypertension (ambulatory BP of 175/95 mm Hg)
and sustained nocturnal hypertension (BP of 175/90 mm Hg). Additional
medication was added. (Courtesy of Ronald G. Victor, MD, Hypertension Division, Department of Internal Medicine, University of Texas
Southwestern Medical Center, Dallas, Texas.)
Masked
hypertension
Nocturnal
hypertension
24:00 11:00
hr:min
Sleep
24:00 16:00
hr:min
receptor in the distal nephron, excessive aldosterone production causes
excessive renal Na+-K+ exchange, often resulting in hypokalemia. The
diagnosis should always be suggested when hypertension is accompanied by either unprovoked hypokalemia (serum K+ less than 3.5
mmol/L in the absence of diuretic therapy) or a tendency to develop
excessive hypokalemia during diuretic therapy (serum K+ less than 3.0
250
200
150
100
50
0
15:00 24:00 15:00
Office visits
hr:min
mmol/L). However, more than one third of patients do not have hypokalemia on initial presentation, and the diagnosis should be considered
in any patient with refractory hypertension. The diagnosis is confirmed
by the demonstration of nonsuppressible hyperaldosteronism during
salt loading, followed by adrenal vein sampling to distinguish between
a unilateral adenoma and bilateral hyperplasia. Laparoscopic adrenalectomy is the treatment of choice for unilateral aldosterone-producing
adenoma, whereas pharmacologic mineralocorticoid-receptor blockade with eplerenone is the treatment for bilateral adrenal hyperplasia.
Mendelian Forms of Hypertension
Nine very rare forms of severe early-onset hypertension are inherited as Mendelian traits. In each case, the hypertension is mineralocorticoid-induced and involves excessive activation of the epithelial
sodium channel (ENaC), the final common pathway for reabsorption of sodium from the distal nephron. The resultant salt-dependent
hypertension can be caused by both gain-of-function mutations of
ENaC (Liddle’s syndrome) or the mineralocorticoid receptor (i.e., a
rare form of pregnancy-induced hypertension) and by increased production or decreased clearance of mineralocorticoids. These include
aldosterone (glucocorticoid-remediable aldosteronism), deoxycorticosterone (17-hydroxylase deficiency), and cortisol (syndrome of
apparent mineralocorticoid excess). Mutations in the potassium channel subunit KCNJ5 and chloride channel CLCN2 have been linked
to familial aldosteronism by increasing aldosterone release and or
increasing proliferation of zona glomerulosa cells.
Pheochromocytoma and Paraganglioma
Pheochromocytomas are rare catecholamine-producing tumors
of the adrenal chromaffin cells. Paragangliomas are even rarer
extra-adrenal catecholamine-producing or nonfunctional tumors
of sympathetic and parasympathetic ganglia. The diagnosis should
be suggested when hypertension is accompanied by paroxysms of
headaches, palpitations, pallor, or diaphoresis. However, the most
common presentation of pheochromocytoma is an adrenal incidentaloma, an incidental adrenal mass discovered unexpectedly
on abdominal imaging for another indication. In some patients,
152 SECTION II Cardiovascular Disease
A
B
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TABLE 12.6 Guide to Evaluation of Secondary Hypertension
Probable Diagnosis Clinical Clues Diagnostic Testing
Renal parenchymal hypertension Estimated GFR <60 mL/min/1.73 m
Urine albumin:creatinine >30 mg/g
Renovascular disease New elevation in serum creatinine, significant
elevation in serum creatinine with initiation of ACEI
or ARBs, refractory hypertension, flash pulmonary
edema, abdominal bruit
Coarctation of the aorta pulses, arm BP >leg Arm pulses >leg chest MR or CT, aortogram
BP, chest bruits, rib notching on chest radiograph
Primary aldosteronism Hypokalemia, refractory hypertension Plasma renin and aldosterone, 24-hr urine potassium,
Cushing’s syndrome Truncal obesity, wide and blanching 24-hr urine cortisol, purple striae, muscle weakness,
Pheochromocytoma Spells of paroxysmal hypertension, palpitations,
perspiration, pallor
Pain in the head
Diabetes
Obstructive sleep apnea Loud snoring, daytime somnolence, obesity, large neck Sleep study
ACEI, Angiotensin-converting enzyme inhibitor; ARBs, angiotensin-receptor blockers; BP, blood pressure; CT, computed tomography; GFR, glomerular filtration rate; MR, magnetic resonance.
2
Renal ultrasound
MR or CT angiography, invasive angiogram
24-hr urine aldosterone and potassium after salt
loading, adrenal CT scan, adrenal vein sampling
dexamethasone suppression test, adrenal CT scan
Plasma and 24-hr urine metanephrines and catechol-
amines, adrenal CT scan
“String of beads”
Fig. 12.11 Computed tomography (CT) angiogram with three-dimensional reconstruction. (A) Classic string-
of-beads lesion of fibromuscular dysplasia. (B) Severe proximal atherosclerotic stenosis of the right renal
artery. (Courtesy of Bart Domatch, MD, Radiology Department, University of Texas Southwestern Medical
Center, Dallas, Texas.)
pheochromocytoma is misdiagnosed as panic disorder. A family history of early-onset hypertension may suggest pheochromocytoma as
part of the multiple endocrine neoplasia syndromes or familial paraganglioma. If the diagnosis is missed, then outpouring of catecholamines from the tumor can cause an unsuspected hypertensive crisis
during unrelated radiologic or surgical procedures; the perioperative
mortality exceeds 80% in such patients.
Laboratory confirmation of pheochromocytoma is made by
demonstrating elevated levels of plasma or urinary metanephrines;
these are methylated derivatives of norepinephrine and epinephrine
that are made in the adrenal medulla and continually leak out into
Proximal stenosis
the plasma even between blood pressure spikes. Pheochromocytomas
are typically large adrenal tumors that can usually be localized by CT
or MR imaging, although nuclear scanning with specific isotopes that
localize to chromaffin tissue is occasionally needed to identify smaller
tumors and paragangliomas.
Treatment of these tumors is surgical resection. Patients must
receive adequate preoperative management with α-blockade followed
by β-blockade and volume expansion to prevent the hemodynamic
swings that can occur during surgical manipulation of the tumor. For
unresectable tumors, chronic therapy with the α-adrenergic blocker
phenoxybenzamine is usually effective.
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