Author
Catherine A. Lynch, MD
Assistant Professor of Surgery and Global Health
Division of Emergency Medicine
Duke University Medical Center
Duke Global Health Institute
Durham, North Carolina
Disclosure: Catherine A. Lynch, MD, has disclosed no relevant financial relationships.
Editor
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Reviewer
John Geibel, MD
Vice Chair and Professor
Department of Surgery
Section of Gastrointestinal Medicine, and Department of Cellular and Molecular Physiology
Yale University School of Medicine
Director, Surgical Research
Department of Surgery
Yale-New Haven Hospital
Disclosure: John Geibel, MD, has disclosed no relevant financial relationships.
An ECG is performed on a 42-year-old man (shown). The patient presented to the emergency department with dull retrosternal chest pain that began acutely with a tearing sensation and has lasted for 3 days. He has been unable to "get comfortable." The patient denies any recent viral infection or significant medical history. He has no family history of cardiovascular disease. The patient is taking no medications and he denies illicit drug use.
What are the findings seen on the patient's ECG?
A. Sinus tachycardia
B. Diffuse ST-segment elevation
C. Hyperacute T waves in the anterior leads
D. Normal axis
E. All of the above
Answer: E. All of the above
The ECG shows sinus tachycardia at 130 bpm with a normal axis, diffuse ST-segment elevation (green arrows), and PR depression (blue arrows) without reciprocal ST-segment depression.
The patient is alert, uncomfortable, and afebrile. His blood pressure is 160/102 mm Hg, with equal and symmetric pulses in both carotid and brachial arteries. He has an early diastolic murmur in the aortic region, with no gallop, pericardial rub, or knock; however, the heart sounds are distant. The patient's pulmonary, abdominal, and neurologic examinations are unremarkable.
What is the next step in diagnostic testing?
A. Cardiac catheterization
B. Chest radiography
C. Chest CT
D. Echocardiography
E. MRI
Answer: B. Chest radiography
A chest radiograph is the next diagnostic step because it can be obtained easily with minimal radiation.
A representative chest radiograph is shown. What is this patient's most likely diagnosis?
A. Mediastinal tumor
B. Proximal aortic dissection
C. Pericarditis
D. Myocardial infarction
Answer: B. Proximal aortic dissection
Although the patient's ECG suggests pericarditis, the history of a sudden tearing sensation at the onset of symptoms is a classic presentation for an acute aortic dissection. Important clues are the profound hypertension with a blowing diastolic murmur in the aortic area. His chest radiograph demonstrated a widened mediastinum, which is a nonspecific finding, but should prompt additional workup based on the clinical presentation. Image courtesy of Radiopaedia.org.
Several aortic dissection classification schemes exist. The dissection on this image is what type aortic dissection?
A. Stanford type A
B. Stanford type B
Answer: A. Stanford type A
The 2 common dissection classification schemes are the Stanford and DeBakey classifications (shown). Aortic dissections are uncommon but potentially catastrophic, with an incidence of 5-30 cases per 1 million people annually.[1] Presenting symptoms depend on the location, direction, and degree of propagation. A proximal vascular disruption allows for slow penetration of blood into the pericardial space, which can cause inflammatory pericarditis.[2,3]
Common risk factors for aortic dissection are shown. The diagnosis of aortic dissection is missed on initial evaluation in 38% of all patients.[4,5] At least 1% of patients have concomitant coronary artery occlusions (from the dissection flap extending into the coronary os), which may precipitate an acute myocardial infarct and left ventricular failure.[6] Lack of recognition of aortic dissection can lead to devastating therapeutic decisions, such as anticoagulation for presumed acute myocardial infarction. The use of heparin and/or thrombolytics in an acute aortic dissection can transform a meta-stable, contained dissection into an exsanguinating mortal event.
Marfan syndrome patients have a very high risk for aortic dissection. The skeleton of patients with Marfan syndrome typically displays multiple deformities including arachnodactyly (ie, abnormally long and thin digits), dolichostenomelia (ie, long limbs relative to trunk length), pectus deformities (ie, pectus excavatum and pectus carinatum), and thoracolumbar scoliosis.[7,8] In the cardiovascular system, aortic dilatation, aortic regurgitation, and aneurysms are the most worrisome clinical findings.[9-12]
Given the widened mediastinum seen on chest imaging, which of the following diagnostic evaluations is the next best choice?
A. Transthoracic echocardiogram (TTE)
B. Transesophageal echocardiogram (TEE)
C. Chest and abdomen CT scan
D. Chest and abdomen MRI
E. None of the above
Answer: C. Chest and abdomen CT scan
A contrast-enhanced CT of the chest, which shows the ascending and descending aortic intraluminal flap (red arrows), is shown indicating a type A dissection. Multiple diagnostic methods can be employed to investigate for aortic dissection if the diagnosis is suspected. These diagnostic methods include chest radiography, TTE, TEE, MRI, or CT scanning. In general, CT scanning is usually the most expeditious and easily obtained imaging modality in the absence of contraindications (such as renal insufficiency). A specialized dissection protocol can be used to provide optimal opacification of the aorta.
Answer: D. TTE
Each method has its own strengths and drawbacks, as shown. In an unstable patient, both a chest radiograph and a TTE can be performed at bedside. As our patient already had chest radiography, a TTE could be informative without causing risk to the patient by requiring transfer to another location for an examination.
The MRI shown demonstrates a small anterior true lumen (red arrows) with a more posterior false lumen. A jet of blood can be seen flowing through an intimal tear (yellow arrow). In stable patients, MRI can provide excellent anatomic detail of an aortic dissection. MRI can accurately depict complications including thrombosis, hemorrhage, infection, pseudoaneurysm, aortoenteric fistula, and ureteral obstruction.
Overall, the mortality of an untreated aortic dissection is high, with the highest risk being within the first 24 hours.[13] The mortality rates by different timepoints are shown. In most patients who die with proximal aortic dissections, the cause is usually rupture, aortic insufficiency, or branch-vessel obstruction.[14]
Acute medical therapy is directed at stabilizing the patient, preventing further propagation of the dissection, and enabling the patient to survive until definitive operative therapy can be performed. This approach is termed "anti-impulse" therapy by lowering blood pressure with intravenous vasodilators and controlling the heart rate to decrease the force of cardiac contractions.[5] The goal of acute medical therapy is to maintain a blood pressure and heart rate that is as low as possible while still maintaining mentation and end-organ perfusion.
Medical management remains the treatment of choice for descending aortic dissections, unless they are leaking or ruptured. Advances in stenting technology have made stenting a viable option in select patients.[15-20] Surgical or endovascular correction is mandated for any ascending thoracic aortic dissection. The objective is to resect the most severely damaged segments of the aorta and to obliterate the entry of blood into the false lumen, both at the initial intimal tear and at any secondary tears.[21-23] While excision of the intimal tear may be performed, it does not significantly change mortality. Use of a vascular ring connector has a larger contact surface area than traditional stitches and thus provides a stronger anastomosis and better surgical results.[1]
This image is an oblique arteriogram of the thoracic aorta demonstrating the double-barrel aorta sign of aortic dissection. Both the true (yellow arrow) and false (red arrow) lumens are opacified.
The experience of the surgeon and surgical center is critical in assessing the appropriate type of surgical repair and ensuring a good outcome. In high-volume centers, the survival rate from acute aortic dissection is 85%.[24]
The patient in this case received medical management in the emergency department and had a surgical repair for an ascending aortic dissection from which he recovered fully and was discharged within 1 week.
Author
Catherine A. Lynch, MD
Assistant Professor of Surgery and Global Health
Division of Emergency Medicine
Duke University Medical Center
Duke Global Health Institute
Durham, North Carolina
Disclosure: Catherine A. Lynch, MD, has disclosed no relevant financial relationships.
Editor
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Reviewer
John Geibel, MD
Vice Chair and Professor
Department of Surgery
Section of Gastrointestinal Medicine, and Department of Cellular and Molecular Physiology
Yale University School of Medicine
Director, Surgical Research
Department of Surgery
Yale-New Haven Hospital
Disclosure: John Geibel, MD, has disclosed no relevant financial relationships.
Abdominal Vascular Occlusion
Acute Stroke
Are You Missing an MI?
Dissection, Aortic
Easy-to-Miss Findings on Chest Radiographs
Life-Threatening Pericardial/ Myocardial Pathology
