March 2015

A 79-year-old woman found dead on the floor in her home

Janice Ahn, M.D., and Vernard Adams, M.D.

Overview

A 79-year-old woman with chronic obstructive pulmonary disease, hypertension, coronary artery disease, congestive heart failure, and remote myocardial infarction was found lying dead on the floor. The scene investigator thought she had collapsed upon standing from a recliner.

The decedent had been seen more than one year before by a cardiologist where an electrocardiogram revealed a pathologic Q wave with left axis deviation. The cardiologist made the diagnosis of underlying atherosclerotic heart disease with a previous septal infarct on electrocardiogram, chronic dyspnea on exertion exacerbated by chronic lung disease, and chronic hypertension. Though an echocardiogram was recommended, the patient was lost to follow-up.

Gross and Microscopic Descriptions

An autopsy was performed.  The body appeared the stated age of 79 years. The body weighed 119 pounds and was 67 inches long. The pericardial sac had 300 ml of liquid and clotted blood (Figure 1). The great vessels and the chambers of the heart were collapsed (Figure 2).  The heart weight was normal at 280 g. The internal diameter of the left ventricle was slightly dilated at 4.5 cm. The valves were normally formed. The coronary arteries were entirely patent and the myocardial cut surfaces had no infarctions.

The aorta had a 3.2 cm vertical linear intimal tear on the anterior wall of the ascending aorta, 3.0 cm distal to the aortic valve (Figure 3). The tear led to a delamination of the aortic wall media (Figure 4) extending 21.0 cm distal, to the 6th intercostal arteries.  The dissection plane was closer to the adventitia than to the endothelium (Figures 6 and 7, microscopic).  It extended 5 cm into the wall of the right brachiocephalic artery and 1cm into the walls of the left common carotid and subclavian arteries (Figures 8 and 9, microscopic). It did not extend into the coronary arteries. The dissection involved ¾ of the circumference of the ascending aorta and decreased in width through the arch and into the descending aorta, where it ended. The aortic adventitial blood extended through the mediastinal connective tissue into the pulmonary hila. The aorta had uncomplicated atherosclerotic plaques involving an estimated 50% of the intimal surface (Figure 5).

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Figure 1. 300 ml of liquid and clotted blood in the pericardial sac.
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Figure 2. Collapsed chambers of the heart.
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Figure 3. Tear in aortic intimal wall.
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Figures 4. Blood in the aortic dissection plane.
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Figure 5.Uncomplicated atherosclerosis covering 50% of the aortic luminal surface.

Microscopic

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Figures 6 and 7. Aortic dissection plane in the tunica media lined by loose fibrin with sparse polymorphonuclear leukocytes appearing as blood constituents. There is no inflammation.
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Figure 8 and 9. Dissection planes extending to the left common carotid and brachiocephalic arteries.

Diagnosis

90% of aortic dissections involve the: ?

Answer

Please select an answer above.

Discussion

Aortic dissections affect one in 20,000 people per year and result in 3000 deaths in the United States. Two thirds of dissections involve the ascending aorta and most of these patients die before reaching a hospital. The etiology of aortic dissection can be organized into 3 categories: (1) arterial hypertension and (2) connective tissue disorders. Arterial hypertension is the most common chronic disease-associated cause of aortic dissection, occurring at 60-75% of cases. The majority of the remaining cases are caused by connective tissue disorders, the principle culprit being Marfan’s syndrome.  Other connective tissue disorders, which fall under the second category, include Ehlers-Danlos syndrome and Loeys-Dietz syndrome. Additional pathologic entities that increase the risk of developing aortic dissection are bicuspid aortic valve, autosomal dominant polycystic kidney disease, giant cell arteritis, and Behcet’s disease.

The pathophysiology of aortic dissection begins with weakening of the aortic wall media, also known as cystic medial necrosis.  The weakening occurs secondary to mechanical injury due to a high head of pressure or secondary to an innate weakening due to connective tissue disease. The subsequent events are incompletely understood. According to one theory, dissection is initiated by an intimal tear due to increased aortic intraluminal pressure. An alternate theory posits aortic vasa vasorum rupture initiating intra-medial hemorrhage with subsequent rupture of the overlying intima. This is supported by reports of intramural hematoma without intimal tears. Regardless of the inciting event, the underlying aortic medial degeneration allows the tear to create a dissection plane in between the aortic intimal and adventitial walls.

Once a dissection plane is created in the weakened aortic wall, the dissection is free to propagate both proximally and distally along the length of the vessel until the pressure gradient is relieved by rupture back into the lumen, or rupture into a body cavity.  Without intervention, the dissection can involve branches of the aorta, the aortic valve ring, the pericardial space, or, in declining order of likelihood, the left pleural space and the right pleural space.  This may lead to aortic valve regurgitation, myocardial ischemia, cardiac tamponade and exsanguination, respectively.  The clinical manifestations are not limited to the cardiovascular system. Dissection into the carotid arteries causing occlusion of cerebral blood flow can cause neurologic deficits such as altered consciousness or ischemic stroke. Horner syndrome or vocal cord paralysis may present as a result of compression of the superior cervical sympathetic ganglion or the left recurrent laryngeal nerve.

The subject described above did not have marfanoid features. She had a reported history of hypertension but did not have left ventricular hypertrophy. The hypertrophic myocytes seen microscopically support the clinical history. Though she had atherosclerotic disease in the aorta, the coronary arteries were patent and her heart had no myocardial infarction, despite the pathologic Q-wave detected previously on electrocardiogram.  She had had no cardiovascular surgeries and she did not have aortic valvular disease.  She died as a result of pericardial hemorrhage and tamponade secondary to dissecting aortic aneurysm due to essential hypertension.

References

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