Aortic and peripheral arterial diseases may coexist in patients with hypertension. Although aortopathies and peripheral arterial disease can be seen in isolation, more often than not they present in patients with multiple cardiovascular risk factors, hypertension being chief among them. The following addresses the epidemiology and natural history of aortic and peripheral arterial disease, with a specific focus on the contribution of blood pressure to disease progression and mortality. With a vast array of pharmacological options available to treat primary hypertension, subsequently addressed is the issue of which antihypertensive agents are best suited and studied to treat patients with aortic and peripheral arterial disease.
Aortic Disease in Hypertension
Aortic pathologies represent a wide spectrum of disease processes and cross multiple medical and surgical subspecialties. Aortic disease can present suddenly and catastrophically, or may be found incidentally on unrelated imaging studies. Although many infectious, inflammatory, and genetic conditions can contribute to disease processes found in the aorta, appropriate blood pressure control represents a pillar in the prevention of disease progression. The focus of the following is thoracic aortic disease with some discussion of abdominal aortic aneurysmal disease in the setting of hypertension.
Thoracic Aortic Disease
The term thoracic aortic disease (TAD) encompasses a varied range of disease processes that range from life threatening upon presentation, to incidentally discovered and asymptomatic. A comprehensive review of all aspects of TAD management is addressed in guidelines published in 2010. Hypertension plays a significant role in the development of TAD in combination with multiple other risk factors including age, atherosclerosis, smoking, and underlying genetic and congenital factors.
The normal adult thoracic aorta is composed of three layers (intima, media, and adventitia) and four primary portions including the aortic root, the ascending aorta, the aortic arch, and the descending aorta ( Fig. 45.1 ). Normal size ranges have been published based on two-dimensional echocardiographic and computed tomography data accounting for factors such as an individual’s age, sex, and body size. These tables aid the clinician in identifying patients with aneurysms or those at risk for aneurysm formation, but do not necessarily account for certain genetic abnormalities and tissue characteristics that place patients at risk for disease processes such as dissection. The major histopathological disease processes that affect the thoracic aorta include atherosclerosis, inflammatory disease, and vasculitides, as well as dissection and aneurysm formation.
Genetic, inflammatory, and congenital conditions are associated with TAD and increase the risk of aneurysm, dissection, and rupture. Genetic syndromes strongly associated with TAD in the form of aneurysms and dissection include Marfan, Loeys-Dietz, vascular Ehlers-Danlos, and Turner syndromes. Other cardiovascular conditions that place individuals at risk for dissection and aneurysm formation include individuals with bicuspid aortic valve and/or aortic coarctation.
Acute Aortic Syndromes (i.e., Aortic Dissection)
Disease processes classified as acute aortic syndromes (AAS) include, most commonly, aortic dissection (AoD) and the less frequently encountered intramural hematoma (IMH), and penetrating atherosclerotic ulcer (PAU). They represent interconnected emergent aortic conditions with similar clinical features and oftentimes are challenging to treat effectively. IMH and PAU may be thought of as variants or precursors to AoD and data regarding blood pressure management in these patients are similar to patients with AoD. Traumatic aortic disease (i.e., aortic disruption) may also be classified as an AAS, but is beyond the scope of this chapter.
Aortic Dissection
The incidence of AoD is difficult to define given that dissections may be rapidly fatal and are frequently missed on initial presentation. When patients die before reaching, or shortly after presenting to, a hospital, death may be mistakenly attributed to another more common cause such as myocardial infarction (MI) or sudden cardiac death. A recent prospective population-based study reveals the incidence of AoD to be 6 cases per 100,000 person years, a significant increase from prior estimates. Risk of aortic dissection increases with age and male sex is a risk factor.
Classification of aortic dissections is based on two major systems, Stanford and DeBakey classification schema. The Stanford system is more widely used in clinical practice. Stanford type A dissections involve the ascending aorta with or without the aortic arch or descending aorta. Type B dissections involve the descending aorta without any involvement of the ascending aorta ( Fig. 45.2 ). Dissections involving the ascending aorta and aortic arch vessels are at highest risk for complications including stroke. These Type A dissections are best treated with emergent surgical management. A key factor in management of type B dissections is determining the presence of complications. Complications are defined as organ or limb malperfusion, progressive dissection, extra aortic blood collection (impending rupture), intractable pain, or uncontrolled hypertension. Short-term survival (3-year) appears to be unaffected by endovascular treatment in acute uncomplicated type B dissections compared with medical management as demonstrated by the INSTEAD trial. However, the INSTEAD XL-trial demonstrated that endovascular treatment in addition to optimal medical therapy is associated with improved 5-year aorta-specific survival and delayed disease progression.
On the other hand, complicated type B dissections may benefit from endovascular intervention as described in Study for the Treatment of complicated type B Aortic Dissection using Endoluminal repair (STABLE) trial, a prospective, multicenter study evaluating safety and effectiveness of a pathology-specific endovascular system (proximal stent graft and distal bare metal stent) for the treatment of complicated type B aortic dissection. It demonstrates that endovascular repair of complicated type B dissections with the use of a composite construct results in early clinical outcomes and aortic remodeling. Of note, patients treated acutely may be prone to aortic growth and may require close observation. Patient follow-up is still on-going.
Timely identification of the intimal disruption, location of dissection, and the involved vessels is crucial to prognosis as well as management decisions (open-surgical, medical, and/or endovascular). Classically, aortic dissection has been temporally categorized based on time of symptom onset with acute aortic dissection defined as diagnosis less than 14 days from symptom onset, and chronic defined as diagnosis greater than 14 days from symptom onset. Given the advances in care for patients with AoD, recent work proposes more nuanced categorization (hyperacute [symptom onset to 24 hours], acute [2 to 7 days], subacute [8 to 30 days], and chronic [>30 days]) based on Kaplan-Meier survival curves developed using the International Registry of Acute Aortic Dissection (IRAD: a consortium of research centers that are evaluating the current management and outcomes of acute aortic dissection involving 30 large referral centers in 11 countries), although this has not yet been formally adopted in guidelines.
Increased aortic wall stress and conditions that encourage aortic medial degeneration increase one’s risk of dissection. The majority of patients diagnosed with AoD have hypertension and the prevalence is increasing. Underlying genetic syndromes are not uncommon in patients with AoD, especially younger patients. Presentation of aortic dissection and complications are varied and numerous, with rapid assessment, diagnosis, and treatment resulting in much better outcomes.
Half of all patients with aortic dissections present with elevated systolic blood pressures (SBPs) (>150 mm Hg) and alternatively, 20% of patients present with hypotension and/or shock. As outlined in comprehensive thoracic aortic disease guidelines published in 2010, accurate blood pressure (BP) measurement at the time of dissection may be complicated in the setting of dissection-related occlusion of branching arteries, resulting in incorrectly low BP measurement in affected limbs. As such, BPs should be measured in both arms and, oftentimes, both legs to determine the highest central BP. Pulse pressure (PP), at the time of presentation, may also be a prognostic value in those with type A dissections. IRAD investigators recently determined that patients with type A AoD with narrow PP (<40 mm Hg) were more likely to have cardiac complications such as cardiac tamponade, whereas those with PP greater than 75 mm Hg were more likely to have abdominal aortic involvement.
Diagnosis imaging modalities to rule out aortic dissection are numerous. Meta-analyses demonstrate that contrast computed tomography (CT), transesophageal echocardiography (TEE), and magnetic resonance imaging (MRI) all provide valuable diagnostic information. Given that it is the most readily available imaging modality, CT is often the imaging modality of choice in hemodynamically stable patients. Those that are unstable are better suited for TEE.
Upon diagnosis of thoracic AoD, initial management should focus on decreasing aortic wall stress, by controlling heart rate and BP, to prevent propagation of the false lumen potentially leading to subsequent complications including rupture and/or malperfusion. Simultaneous discussion for definitive management should also be undertaken with surgical colleagues (regardless of dissection location, ascending or descending). Intravenous beta-blockade (in the absence of contraindications) should be administered to target a heart rate of less than 60 beats per minute. In patients with a contraindication to beta-blockade, nondihydropyridine calcium channel blockers should be administered with the goal of similar heart rate reduction (for example diltiazem or verapamil). Simultaneously, with heart rate control, the SBP should be addressed. If a patient’s SBP remains above 110 mm Hg with medication administration as noted above, angiotensin-converting enzyme inhibitors and/or other vasodilators should be given to further reduce SBP while maintaining adequate end-organ perfusion. Rapid diagnosis and initial blood pressure/heart rate management for acute type A dissection is the key for successful management transition to definitive surgical therapy. At our institution, we developed an aortic dissection flowsheet to facilitate and generalize the management ( Fig. 45.3 ). Appropriate initial heart rate control is critical before initiating vasodilator therapy, because the reflex tachycardia induced by vasodilators can increase aortic wall stress and worsen the existing dissection. Along similar lines, cautious beta-blocker administration in those patients with aortic insufficiency is warranted given the appropriate need for a compensatory tachycardia to maintain cardiac output.
The choice of beta-blocker is not crucial, as long as the desired heart rate and blood pressure lowering is achieved. However, intravenous labetalol may be the best initial choice given that it is both an alpha-receptor and beta-receptor antagonist. Theoretically, in addition to effective heart rate lowering, it also offers more BP lowering than beta-blockers that do not have additional alpha-blocking properties, potentially eliminating the need for multiple antihypertensive vasodilators. This is not an insignificant factor given that it is oftentimes difficult to reduce BP to endorsed levels and multiple antihypertensive agents may ultimately be needed. In addition to beta-blockers, other established agents for BP control during this critical time include intravenous nicardipine, nitroglycerin, fenoldopam among others whereas sodium nitroprusside should be considered a contraindication in the setting of acute type dissection as a result of an aggravating effect for spinal ischemia. An additional key intervention after diagnosis of aortic dissection is appropriate pain control. Sympathetic activation in setting of uncontrolled pain may worsen a patient’s tachycardia, raise BP, and will be difficult to treat.
Not surprisingly IRAD investigators demonstrated that uncomplicated type B dissections with appropriately controlled pain and hypertension have lower in-hospital mortality than those patients with uncontrolled hypertension and/or pain. Interestingly, the basis for the widely accepted need for intensive SBP control (less than 120 mm Hg) in acute aortic dissection is decades old case series evidence and although the recommendation is class I, it is level of evidence C. This suggests that further investigation of BP goals in acute medical treatment of aortic dissection is needed.
Following initial stabilization with intravenous antihypertensives, and in certain cases surgical management (open or endovascular) based on the location and complexity of the dissection, most patients will require long-term antihypertensive treatment. This should include a beta-blocker plus additional classes of BP lowering medications as detailed later.
Long-Term Blood Pressure Management Following Repair of Type A Dissections
In-hospital mortality for type A dissections has decreased from 31% to 22% in the past 17 years in the IRAD registry. Interestingly, more contemporary large single center data reflect a lower in-hospital mortality rate of closer to 10%. As such, long-term management strategies for these patients is crucial to prevent future events and complications. Data with respect to long-term survival of patients with repaired type A dissections are not robust, although the IRAD investigators report relatively high 3-year survival among patients who survived operative repair of their dissection. The study of patient characteristics impacting survival primarily focuses on preoperative and intraoperative characteristics, such as a patient’s comorbidities and the type of repair chosen. However, a recent retrospective review of patient characteristics impacting long-term outcomes following type A dissection repair, highlights the importance of blood pressure control and choice of antihypertensive medication, even after operative repair.
Amongst patients who survived operative repair, four main factors, male sex, Marfan syndrome, elevated SBP, and the absence of beta-blocker therapy significantly impacted the need for reoperation. Further, at 10-year follow-up, of those patients that maintained an SBP less than 120 mm Hg, only 8% required reoperation, compared with 26% in patients with SBP between 120 and 140 mm Hg, and 51% in those with SBP greater than 140 mm Hg. Similarly, patients taking beta-blockers at 10 years postrepair had an 86% freedom from reoperation, compared with 57% for those not taking beta-blockers. The IRAD investigators demonstrate similar beneficial effects of beta-blockade in survivors of type A AoDs, albeit over a shorter follow-up time (less than 5 years). Although the data are retrospective and include relatively low numbers, the pathophysiologic mechanism is sound. Beta-blockers, and strict BP control, diminish stress on the already diseased aorta, with a concurrent decrease in dP⁄dT (impulse), resulting in less aortic damage over time. Further long-term prospective study is needed, but it is very reasonable to aim for strict BP control in this subgroup of patients, with beta-blocker therapy as a first-line agent.
Long-Term Blood Pressure Management Type B Dissections
Recently, management paradigms of type B dissections have shifted based on the use of thoracic endovascular aortic repair (TEVAR) in complicated dissections, and some suggestion that even uncomplicated low-risk patients may demonstrate long-term benefit from preemptive or early endovascular repair. Irrespective of interventional management, control of BP remains a hallmark of immediate and long-term management of type B AoDs.
Similar to type A dissections, no high-level of evidence data exist regarding specific BP goals in patients with a history of type B AoD. Current guidelines recommend BP control similar to that of the general population ; however this may change in the wake of results from the SPRINT BP trial that demonstrated increased survival with more intensive BP goals in the general population. Beta-blockers are currently recommended in all patients with type B AoD based on data in Marfan syndrome patients that beta-blockade attenuates aneurysmal expansion. A recent systematic review attempted to establish the efficacy of beta-blockers versus other antihypertensives in this patient population. Unfortunately, no randomized control trials (RCTs) compare first-line beta-blockade with other first-line antihypertensive medications in the treatment of chronic type B AoD. The authors conclude that it is unknown whether beta-blockers as first-line therapy is appropriate, and future randomized controlled trials are needed.
However, there are some nonrandomized data to help guide clinical decision-making. A study of 71 patients with type B dissection that survived to hospital discharge, with approximately of 4 years of follow-up, suggests benefit of beta-blockade. Of the 50 patients treated with beta-blockers chronically, 10 required surgery for aortic dissection. This stands in contrast to 9 of 20 patients not treated with beta-blockers who required surgery for aortic dissection. Contrasting that data is a study from 2008, of patients with type B AoD treated medically with an average of 2.5 years of follow-up. Multivariate analysis did not demonstrate a reduction in long-term aortic events with beta-blocker administration, but did see a benefit in those patients prescribed angiotensin-converting enzyme inhibitors. Similarly, data from the 5-year IRAD follow-up do not demonstrate long-term benefit of beta-blockade on survival in patients with type B dissections. Interestingly, this multivariate analysis found that use of calcium channel blockers was associated with improved survival.
Aortic dissection is not a common end-point (primary or secondary) in large cardiovascular (CV) trials, including those looking at antihypertensive therapy. Taken as a whole, data with respect long-term BP management in type B dissections are limited at best and no specific class of antihypertensive demonstrates superiority aside from patients with Marfan syndrome.
Physical Activity and Lifestyle Recommendations Following Aortic Dissection
Lifestyle and physical activity restrictions are reasonable in patients with a history of thoracic aortic disease, even in those with repaired AoD, as a result of their effect on BP and aortic stress. Aerobic exercise should be encouraged in these patients because it is beneficial for overall cardiovascular health and wellbeing. However, sudden increases in dP/dt and blood pressure associated with certain physical stressors, particularly isometric exercise, may trigger AoD or rupture of aneurysms. Guidelines recommend advising patients to refrain from activities such as weightlifting and sports that may result in thoracic stress and trauma, or involve rotational movement while straining or breath-holding (Valsalva maneuver). Similarly, the sudden increase in aortic stress and systemic arterial pressure produced by activities such as lifting boxes and moving furniture should preclude patients with a history of TAD from the occupations.
Thoracic Aortic Aneurysms
Degenerative disease results in dilatation of the aorta, leading to thoracic aortic aneurysm formation (TAA). The incidence of TAA is increasing (it is currently 10.4 cases per 100,000 persons years) and influenced by risk factors similar to those for atherosclerosis, including age, smoking, hypertension, a family history of aneurysmal disease, and hypercholesterolemia. Inflammatory, genetic, and certain congenital conditions also influence and increase the risk of aneurysm formation or dissection (see Box 45.1 ). Oftentimes patients are asymptomatic at the time of diagnosis and the aneurysm is found due on unrelated chest imaging, such as chest x-ray or CT. However, patients may present with symptoms related to anatomic enlargement of the aneurysm, including compression of surrounding structures.
Inflammatory
- •
Takayasu arteritis
- •
Giant cell arteritis
- •
Behçet disease
- •
Ankylosing spondylitis (spondylarthropathies)
- •
Infective thoracic aortic aneurysms
- •
Syphilis
Congenital
- •
Bicuspid aortic valve
- •
Abberrant right/left subclavian artery
- •
Coarctation of the aorta
- •
Right aortic arch, double aortic arch
Genetic
- •
Marfan syndrome
- •
Loeys-Dietz syndrome (TGF-β Thoracic Aortic Disease Syndromes)
- •
Vascular Ehlers-Danlos syndrome
- •
Turner Syndrome
- •
Familial thoracic aortic aneurysm and dissection (ACTA 2, MYH11, TGFBR1, FBN1)
Trauma
- •
Motor vehicle accident
- •
Catheter procedure
- •
Open heart/aortic/vascular surgery
The definition of a true aneurysm is a segmental, full-thickness dilation of a blood vessel having at least a 50% increase in diameter compared with the expected normal diameter. In the case of the aorta, true aneurysms involve all three layers (intima, media, and adventitia). Similar to AoD, TAAs may affect varying segments of the aorta ( Fig. 45.1 ). The majority of aneurysms of the TAA affect the ascending aorta (60%), followed by descending, with only approximately 10% involving the aortic arch, although there is a variation depending on race and regions. Descending thoracic aortic aneurysms have a unique classification system that allows for more detailed information regarding the extent of aortic involvement ( Fig. 45.2 ).
The natural history of all aortic aneurysms is slow but progressive enlargement with increasing risk of aortic rupture or dissection as size increases. Rates of growth/expansion vary based on aneurysm location, pathogenesis, and size. Given the progressive nature of this disease process, regular surveillance and screening are recommended in certain high-risk populations, with more frequent imaging recommended as aneurysmal size increases and operative repair recommended at specific thresholds. In addition, control of risk factors for further aneurysm growth is recommended, including aggressive BP and cholesterol management, as well as smoking cessation.
Multiple studies have been undertaken in an attempt to limit or halt the progression of thoracic aortic aneurysmal growth via medical therapy in patients with asymptomatic disease, who do not have an indication for surgery (i.e., aneurysm is not rapidly expanding, nor has it reached the size threshold for surgical intervention). The most significant study, which demonstrates a slowing of aortic dilation, was performed in patients with Marfan syndrome who are at very high-risk for aortic dilation and aneurysm formation. Seventy patients were randomized to propranolol, versus no beta-blockade, in an open-label study with 10 years of follow-up. The rate of aortic dilation was 73% less in the propranolol group, when compared with the control group.
Similar to beta-blockade in AoD, the mechanism is thought to be a decrease in left ventricular dP/dt and shear stress. Although this beta-blockade benefit has not been specifically demonstrated in non-Marfan syndrome patients, the valid physiological basis has led to general consensus for medical therapy of TAAs to include beta-blockade as first-line therapy.
Further study of Marfan patients has addressed the role of renin-angiotensin system blockade, and attempted to determine if that could also reduce the rate of aneurysmal expansion. An initial small study of 17 adult patients demonstrated when perindopril is added to beta-blocker therapy aortic wall stiffness and aortic root stiffness are decreased. Subsequently, a larger open-label randomized study of losartan versus placebo treatment in 233 adult patients with Marfan syndrome demonstrated a significantly decreased rate of aortic root dilation in those treated with losartan. Over 70% of patients enrolled in this study were also taking beta-blockers. The most recent work evaluating medical therapy’s role in decreasing aortic root dilation/aneurysmal progression was published in 2014. A total of 608 adult and pediatric subjects were assigned to treatment with losartan or atenolol. No significant difference in the rate of aortic-root dilatation between the two treatment groups was seen over a 3-year period. Rates of aortic-root surgery, aortic dissection, death, and a composite of these events also did not differ significantly between the two treatment groups.
Again, the degree of BP lowering in patients with TAAs is not well established. It may be reasonable to aim for aggressive BP goals (<120 mm Hg), in the absence of other comorbidities such as diabetes mellitus. Using data extrapolated from patients with Marfan syndrome, the use of beta-blockers is recommended to slow TAA progression, and the use angiotensin-receptor blockers are reasonable as second-line therapy in hypertensive patients with TAA.
Abdominal Aortic Aneurysms
Abdominal aortic aneurysms (AAA) are the most common form of arterial aneurysm and accounted for 151,500 deaths in the United States in 2013. In the majority of adults an abdominal aortic diameter of greater than 3.0 cm is defined as aneurysmal and occurs most frequently below the renal arteries. The natural history of AAAs includes progressive increases in size, the rate of which varies based on a variety of risk factors including increasing age, male sex, smoking, hypertension, and atherosclerosis. Interestingly, diabetes appears to lessen the likelihood of developing an AAA.
Of course, with increasing aneurysmal size the risk of rupture, and subsequent mortality, increases. Independently, the rate of AAA expansion also increases the risk of rupture. A 2015 study assessed factors associated with small AAA expansion rate and determined that elevations in diastolic blood pressure were tied to increased expansion rates. This is similar to a 2014 study of 1.25 million individuals aged 30 and above that were free from atherosclerotic cardiovascular disease that were followed for a median of 5.2 years. Although AAA was very weakly associated with systolic hypertension, of all cardiovascular conditions, AAA demonstrated the strongest association with diastolic blood pressure (DBP) and mean arterial pressure. It also was the only cardiovascular condition studied that demonstrated a reverse relationship with increasing PP (i.e., less AAA development with increasing PP.) This may reflect that arterial rigidity seen with increasing PP is in fact protective against aneurysm formation.
The United States Preventive Task Force (USPTF) developed guidelines for AAA screening in the general population that includes the recommendation for ultrasound screening of men with a smoking history between the ages of 65 and 75 years. “Clinically selective” screening is recommended in men ages 65 to 75 years who have never smoked but have risk factors for AAA. Women who have never smoked should not be screened, and there is insufficient evidence to recommend screening in women who have smoked according to the USPTF. There are also recommendations based on randomized control trials and a recent meta-analysis favoring elective operative repair (be it open or more commonly endovascular repair) when aneurysm size reaches greater than 5.5 cm in diameter. However only a small proportion of patients, when initially diagnosed with an AAA, meet criteria for aneurysm repair. Thus, before operative repair is indicated, observation and medical management are therapy mainstays.
As one would imagine, medical therapy includes overall cardiovascular risk reduction with the goal of slowing aneurysm growth and optimizing cardiovascular risk factors. Smoking cessation is the most significant modifiable risk factor when attempting to limit aneurysmal expansion. Other common modifiable risk factors, such as statins and antiplatelet therapy, have been studied with respect to aneurysmal size changes and do not demonstrate a significant difference.
Antihypertensive Treatment in Setting of AAA
Of course, appropriate blood pressure control reduces an individual’s overall cardiovascular risk and this benefit is seen in patients with abdominal aortic disease. Multiple studies have investigated whether antihypertensive medications decrease aneurysm expansion rates, but none demonstrates a clear impact on AAA size. Diuretics do not appear to have any effect on expansion rates. Beta-blockers are amongst the most studied and are of uncertain benefit in limiting AAA expansion. Although animal and retrospective studies suggested beta-blockers may limit AAA growth, prospective randomized control trials do not demonstrate a significant difference. A 548-subject randomized placebo controlled trial of propranolol administration to limit expansion of small AAA (mean size of 3.8 cm) demonstrated no significant difference in growth rate and demonstrated poor tolerance of beta-blockade in the active treatment group. It is unknown whether a better tolerated (i.e., more selective beta-blocker) may result in better patient compliance and a beneficial effect.
Blockade of the renin-angiotensin-aldosterone system, with angiotensin receptor blockers or angiotensin converting enzyme inhibitors, has also been studied in attempts to decrease AAA growth. Data from these trials are conflicting and current studies are ongoing as noted below. A 2010 prospective cohort study suggested that treatment with angiotensin converting enzyme inhibitors may in fact lead to aneurysm growth in patients with small AAAs. This stands in contrast to a 2006 population-based case control study suggesting the opposite. Clearly further investigation is needed in the form of randomized control trials. A current phase 2 trial has been completed, but not yet published ( ClinicalTrials.gov NCT01118520 ) comparing rates of AAA expansion when treated with perindopril versus amlodipine versus placebo. A stage 4 trial of telmisartan versus placebo treatment ( ClinicalTrials.gov NCT01683084 ) in AAA is also ongoing, with anticipated completion in mid-2016.
Aortic Coarctation
Coarctation of the aorta is most commonly described as a narrowing of the descending aorta located opposite the closed ductus arteriosus (ligamentum arteriosum), just distal to left subclavian artery. Anatomically, there is a ridge-like in-folding of the aorta, resulting in encroachment upon the aortic lumen. Classically an “infantile” form of aortic coarctation also exists, with narrowing proximal to a patent ductus arteriosum (PDA), which manifests early in childhood as cyanosis, and requires surgical and/or catheter-based interventions in the neonatal period. Taken together, coarctation of the aorta is a congenital heart defect that accounts for approximately 5% of all congenital cardiac malformations and can be seen as a solitary defect, or in combination with other cardiac abnormalities such as a bicuspid aortic valve. Rarely, aortic coarctation may be acquired following inflammatory disease of the aorta or severe atherosclerosis.
Coarctation of the aorta without a PDA is a commonly discussed cause of secondary hypertension and is oftentimes unrecognized well into adulthood. Because it is often unrecognized, 2008 guidelines for the management of adults with congenital heart disease from the American Heart Association and American College of Cardiology recommend screening for coarctation in both hypertensive children and adults. This includes palpating brachial (or radial) and femoral pulses simultaneously to assess timing and amplitude; looking for a brachial-femoral delay seen in significant aortic coarctation ( Fig. 45.4 ). Further, upper and lower extremity BP measurement should be performed. Typical findings in coarctation of the aorta include elevated SBP in the upper extremities, diminished or delayed femoral pulses, and low or unobtainable arterial BP in the lower extremities with possible manifestation of arterial insufficiency symptoms such as claudication. The origin of the left subclavian artery and the severity of the luminal narrowing determine the severity of pulse and BP discrepancy. If suspected on physical exam, two-dimensional and Doppler echocardiography is the typical confirmatory study. CT and MRI are complementary imaging modalities that may also help establish the diagnosis.
