Aortic dissection follow-up

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Follow-up
The long term follow-up in individuals who survive aortic dissection involves strict blood pressure control. The relative risk of late rupture of an aortic aneurysm is 10 times higher in individuals who have uncontrolled hypertension, compared to individuals with a systolic pressure below 130 mmHg.

The risk of death is highest in the first two years after the acute event, and individuals should be followed closely during this time period. 29% of late deaths following surgery are due to rupture of either the dissecting aneurysm or another aneurysm. In additions, there is a 17 to 25% incidence of new aneurysm formation. This is typically due to dilatation of the residual false lumen. These new aneurysms are more likely to rupture, due to their thinner walls.

Serial imaging of the aorta is suggested, with MRI being the preferred imaging technique.


 * DeBakey and Cooley reported the first successful operation for resection and graft replacement of the ascending aorta using cardiopulmonary bypass in 1956.
 * Any dissection that involves the ascending aorta is considered a surgical emergency. Without surgery, there is a 90% 3-month mortality. These patients can rapidly develop acute aortic insufficiency (AI), tamponade or myocardial infarction (MI). Even acute MI in the setting of dissection is not a surgical contraindication. Acute hemorrhagic stroke is, however, a relative contraindication, due to the necessity of intraoperative heparinization.
 * Operative mortality for ascending dissections is surgeon dependant, and averages ~ 5 – 20 %. This however, is well below the 50% mortality when these cases are managed with medical therapy.
 * Factors that increase surgical risk include renal insufficiency, visceral ischemia, tamponade and underlying pulmonary disease.
 * Surgical therapy involves excision of the intimal tear, obliteration of the proximal entry site into the false leumen, and reconstitution of the aorta with placement of a synthetic graft. AI can be corrected by resuspension of the native valve, or by aortic valve replacement (AVR).
 * Dissections involving the descending aorta only can be managed medically unless there is progression or continued hemorrhage into the pleural or retroperitoneal space. The major surgical complication in descending dissections is spinal cord ischemia and paralysis.
 * Medical management centers around blood pressure control and decreasing the velocity of left ventricular contraction with the goal of decreasing aortic shear stress. Pain control with morphine is also extremely important. For patients with DeBakey III or Daily B dissections, medical therapy offers an > 80% survival rate.
 * The systolic blood pressure is kept at the lowest level tolerated. Initial treatment usually involves either Labetalol (20mg bolus f/b 20-80mg q10min to a total dose of 300mg, or as an infusion of 0.5 – 2 mg/min) or Propranolol (1 – 10 mg load f/b 3mg/hr) with the goal heart rate ~ 60 BPM. Lopressor and Verapamil can also be used.
 * If the heart rate is controlled, and the systolic blood pressure (SBP) is > 100 mmHg with adequate mentation and urine output, Sodium Nitroprusside is added (0.25 – 0.5 ug/kg/min). Nitroprusside should never be used prior to beta blockade, as the hypotension can result in a reflex tachycardia.
 * All patients should have an arterial line in the arm with the higher BP for accurate monitoring.

Acknowledgements
The content on this page was first contributed by: David Feller-Kopman, MD and C. Michael Gibson M.S., M.D.