Aortic Dissection see Chap54

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Because aortic dissection is associated with hypertension in about 90 percent of cases, medical therapy aimed at reducing blood pressure can limit the extent of the dissection. The process begins as a tear in the aortic intima, allowing blood to dissect into the media and then to reenter the lumen of the aorta via a second intimal tear, resulting in a double-barreled aorta. Approximately half of all nontraumatic dissections begin in the ascending aorta, a third in the arch, and the rest in the descending aorta. The dissection may extend proximally to involve the carotid arteries, coronary arteries, or pericardium, or it may extend distally to include the spinal artery or renal arteries.

The classic description is the abrupt onset of severe, tearing chest pain, radiating to the back or the abdomen. The location of the pain, the signs and symptoms, and the findings on physical examination vary with the site of the dissection and the direction in which it extends. The blood pressure is generally elevated but may be normal or even low. There may be differences in the pulses and blood pressure in different extremities. Because of the variety of presentations, the diagnosis of aortic dissection is often a difficult one and may require the aid of imaging studies. In 80 to 90 percent of cases, the chest x-ray may show a widening of the cardiac silhouette or, less often, a widened superior mediastinum may be evident. The chest x-ray may also show a separation of calcified intima from the aortic wall, but other more definitive studies, including transesophageal ultrasound, CT, magnetic resonance imaging, and aortography, may be needed to confirm the diagnosis and identify the level of dissection (see Chap 54 for details).

The initial medical therapy for a suspected dissection is the use of an antihypertensive agent to lower the blood pressure and reduce the ventricular ejection force (rate of change in pressure with time, dp/dt) of the heart. Treatment of choice includes either a combination of a b-adrenergic antagonist (such as esmolol) and sodium nitroprusside, or labetalol alone. Emergency surgical consultation should be obtained for all suspected aortic dissections, although dissections involving the descending aorta are often medically managed. Surgical intervention is indicated in dissections involving the ascending aorta or aortic arch and in cases in which pain and blood pressure cannot be adequately controlled.

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Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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