CHAPTER 14 Acute Hypertensive and Aortic Syndromes
Gregory W. Serrao and Umesh K. Gidwani
Icahn School of Medicine at Mount Sinai, New York, NY, USA
Background
Hypertensive urgency is defined as severely elevated blood pressure >220 systolic or >120 diastolic.
Hypertensive emergency is defined as severely elevated blood pressure with signs of end‐organ damage.
In the cardiac critical care setting, hypertensive emergency can manifest as aortic dissection.
Incidence/prevalence
Hypertensive emergency of any kind is common with approximately 1–5% of those who have hypertension experiencing a hypertensive emergency over their lifetime.
Incidence of aortic dissection is estimated at 30 cases per million individuals per year.
Etiology
Chronic hypertension predisposes to both hypertensive emergency and aortic dissection.
Several conditions can predispose to aortic dissection including Marfan’s syndrome, vasculitis, syphilis, and Turner’s syndrome.
Pathology/pathogenesis
Blood enters the media layer of the aorta and forces apart the intimal layer and creates a false lumen which can lead to aortic rupture, hemopericardium, or ischemic injury to any end organ dependent on flow from the affected region of the aorta (Figure 14.1).
Predictive/risk factors
Hypertension.
Genetic/congenital aortic disease.
Atherosclerosis.
Trauma.
Cocaine use.
Inflammatory/infectious diseases of the aorta.
Pregnancy.
Prevention
Weight reduction, diet modification, avoidance of smoking, and control of cholesterol may prevent hypertension and aortic disease.
Screening
The US Preventive Services Task Force (USPSTF) suggests adults over 40 years have their blood pressure checked annually; those between 18 and 39 checked annually in the setting of risk factors; those without risk factors and with no known history of hypertension should be checked every 3 years.
The USPSTF suggests males between 65 and 75 years who have a history of smoking should have a one‐time screening for abdominal aortic aneurysm by ultrasonography.
Secondary prevention
Adherence to an antihypertensive regimen and regular medical follow‐up can prevent a second hypertensive emergency or aortic emergency.
Diagnosis
Acute pain is the most common clinical history: pain can occur in the chest, back, or abdomen depending on the location of dissection; dissection in the absence of chest pain is rare.
On exam there may be a pulse deficit or a difference in blood pressure (>20 mmHg) in both arms in the presence of dissection; an aortic murmur may be present if the tear involves the aortic valve; a focal neurologic deficit may be present.
A d‐dimer of <500 ng/mL is highly predictive for excluding dissection.
CXR may show a widened mediastinum. TEE or MRA are useful in a patient who may not be able to tolerate contrast or safely be transported to the CT scanner. The imaging modality of choice is a CT angiogram (Figure 14.2).
Differential diagnosis of aortic dissection
Differential diagnosis
Features
Acute coronary syndrome
Usually gradual onset of chest pain described as tightness or pressure rather than tearing or radiation to the back
Esophageal rupture
Usually preceded by vomiting or an esophageal procedure and will present with concurrent sepsis May have mediastinal crunch
Pulmonary embolism
Pleuritic chest pain often accompanied by tachycardia and hypoxia in the presence of a clear CXR
Pneumothorax
Sudden onset chest pain with absent or decreased breath sounds on one side Subcutaneous emphysema may be present
Pericardial tamponade
Shortness of breath with pleuritic chest pain Easily identified on bedside transthoracic echocardiogram ECG will often show diffuse ST elevations rather than focal
Typical presentation
Aortic dissection typically presents with abrupt onset pain, the location of which may vary depending on the location of the dissection.
The pain may be described as a ripping or tearing, but often is just described as sharp.
The pain is often severe and may be associated with hemodynamic instability or other signs and symptoms due to lack of end‐organ perfusion depending on the location of the dissection.
Clinical diagnosis
A description of the pain is important in diagnosing aortic dissection. Abrupt onset is typical for dissection. It can be in the chest but may also be in the back or abdomen depending on the location. It can be associated with syncope, neurologic symptoms, or signs of heart failure.
Physical examination
There may be a pulse deficit in the carotid, brachial, or femoral artery depending on the location of the dissection.
There may be a significant difference in blood pressure on both arms.
A heart murmur may be found if there is associated aortic regurgitation, which is a diastolic decrescendo murmur; this occurs in half to one‐third of ascending dissections.
A neurologic deficit may be found depending on the location of the dissection.
Laboratory diagnosis
List of diagnostic tests
d‐dimer: useful in excluding dissection if the value is lower than 500 ng/mL.
Multiple experimental tests have been studied (soluble elastic fragments, smooth muscle myosin heavy chain, C‐reactive protein, fibrinogen, fibrillin fragments) but none are validated.
List of imaging techniques
CT angiogram: preferred test in a hemodynamically stable patient.
MRA can be considered in the hemodynamically stable patient with chronic kidney disease.
Echocardiogram: TEE is a quick test that can evaluate for ascending dissection and is ideal in the unstable patient.
CXR: should be used as a screening imaging study in all patients with chest pain and any concern for dissection.
Algorithm 14.1Diagnostic approach to a patient with chest pain and suspected aortic dissection
Potential pitfalls/common errors made regarding diagnosis of disease
In a patient presenting with chest pain, the discovery of a pericardial effusion or acute coronary syndrome, especially in the RCA distribution, does not exclude the possibility of a concurrent aortic dissection.
Aortic dissection can present without pain in 6–10% of patients.
Treatment
Treatment rationale
Ascending dissection is a surgical emergency.
Descending dissection can be treated medically with blood pressure control in most patients.
Table of treatment
Treatment
Comments
Medical Pain control:
Morphine
Beta‐blockers (first line):
Labetolol (20 mg bolus followed by 0.5–2 mg/min)
Propranolol (1–10 mg bolus followed by 3 mg/h)
Esmolol (500 μg/kg bolus followed by 50 μg/kg/min)
Vasodilators (second line): Nitroprusside (preferred second line agent; start at 0.2 μg/kg/min)
Nicardipine (start at 2.5 mg/h)
Enalaprilat (1.25 mg bolus)
Always ensure adequate beta‐blockade prior to starting a vasodilator
Nitroprusside may cause cyanide toxicity and should be avoided in those with renal dysfunction or pregnancy Avoid hydralazine as it may increase shear stress and is less reversible than other methods of blood pressure control
Surgical Open repair Endovascular repair
Ascending aortic dissection is generally managed with open repair If a type B dissection requires surgical management, it often can be done with endovascular techniques
Prevention/management of complications
If using nitroprusside, first ensure adequate beta‐blockade as the vasodilation from nitroprusside may cause an increase in sympathetic tone and ultimately an increase in aortic shear stress.
Avoid direct vasodilators such as hydralazine since they increase aortic wall shear stress.
