The initial management for an aortic dissection often occurs in the emergency room. A patient has an intravenous (IV) line placed, so that medications can be delivered directly into the blood stream. Blood pressure is reduced with medications, usually to 100 to 120 mmHg systolic. Pain is controlled with morphine.
If it is determined that an aortic dissection involves the ascending aorta (DeBakey type I and II or Stanford type A), this is considered a surgical emergency in most patients. Patients are immediately taken to the operating room for repair of the dissection.
If the dissection involves only the descending aorta (DeBakey type III or Stanford type B), the patient is usually treated with medications only. Surgery is usually not recommended for these patients unless complications occur.
Unfortunately, not all patients are candidates for surgery. A patient will need to be able to withstand the stresses introduced by surgery. If it is determined that a patient will be unable to tolerate surgery, medical management will be the patient's best option. The following are factors that suggest a patient should NOT undergo surgery:
- Age > 70
- Abrupt onset of chest pain
- Low blood pressure or shock at presentation
- Kidney failure before surgery
- Decreased pulse
- Abnormal EKG, especially one concerning for heart attack
- Heart attack
- Previous aortic valve replacement
- Possible stroke
Each case, however, is individually evaluated.
The surgery involved in repairing an aortic dissection is very difficult and invasive. As has been stated before, type A dissections require immediate surgical repair. In the operating room, a cardiothoracic surgeon first performs a median sternotomy, a procedure in which a patient's chest is opened. Then, a patient is placed on cardiopulmonary bypass. This means that a patient's blood is routed around the heart and lungs through a machine, so that the body may still receive blood and oxygen while allowing surgeons to operate on the aorta. During this time, the bypass machine can cool the patient's blood, which in turn cools the patient's body and reduces its oxygen requirements. To operate on the aorta, the heart cannot be pumping. Cardioplegic solution, a nutrient-rich solution that slows down the heart, is injected into the heart. This solution greatly reduces its metabolic demands, allowing the heart to be nearly stopped during the procedure yet kept alive.
Surgeons then inspect the aorta to look for the site of the tear that caused the dissection. In addition, they investigate the extent of the tear and determine if anything else, such as other vessels, may have been affected by the dissection. Surgeons suture together the layers of the aorta that were affected, closing the tear that dissected. The aorta is then reinforced with a Dacron graft--a synthetic material--that can be wrapped around the aorta. If necessary, Dacron may also be used to replace portions of the aorta. These grafts usually last an entire lifetime.
If necessary, coronary arteries can be reattached to the heart. If the aortic valve has been affected by the dissection, it may be replaced at this time with a prosthetic valve. Once all repairs are complete, the patient's heart usually restarts on its own after the cardioplegic solution is stopped. If it does not, the heart may need to be shocked with a defibrillator to be restarted. Finally, the patient is taken off cardiopulmonary bypass. The entire procedure lasts anywhere from 5-10 hours, and recovery from surgery usually requires 7-10 days.
As described previously, patients with type B dissections are operated on only in certain situations, such as the formation of a large (>5 cm) aneurysm, organ or limb problems, or evidence of further dissection. These patients receive a similar procedure in which the aorta is reinforced with a Dacron graft and the false lumen is sealed off. However, depending on the location of the dissection, the chest cavity may not be opened. Instead, the aorta may be accessed through an incision on a patient's sides--unfortunately, often a technically more difficult procedure.
Surgery is a very serious, difficult to fathom topic. USNews has published an excellent, informative article about what goes on before, during, and after surgery (not specific to aortic dissections) to help patients learn as much as possible about what is involved with surgery. Please read Navigating the Hospital.
For any patient who has an aortic dissection, medications are extremely important for treatment. All patients will require medication to control their blood pressure. Most patients are initially started on beta blockers, which include medications such as metoprolol and labetalol. These medications work by by blocking the action of adrenaline in your body. Arteries in the body widen and the force of the heart's contraction is decreased. This results in an overall decrease in blood pressure. Other medications such as nitroprusside (a medication that also relaxes the blood vessels), ACE inhibitors, and calcium channel blockers may also be used.
Patients may also be placed on a blood thinner, coumadin, if they receive a mechanical aortic valve. Because of the introduction of a foreign body, mechanical valves greatly increase a patient's risk for blood clots. Coumadin helps decrease this risk.
- Reducing blood pressure to normal limits is the first step in management.
- For Type A dissections, usually emergent surgery is required.
- For Type B dissections, usually medications are the treatment of choice.
Endovascular stent-grafting is now being considered as an alternative to surgery, mostly in stable patients with dissections of the descending aorta. The surgery to correct type B dissections if often technically more difficult than surgery for type A dissections. Endovascular grafts are artificial stents placed through the femoral artery, the large artery that courses down the leg from the aorta. Only small holes in the groin are needed for this procedure, so many patients who are not candidates for surgery can withstand this procedure. This is a new technique that is currently being evaluated, with its own set of complications. Unfortunately, many surgeons are not yet experienced with this method. In addition, further studies are needed to determine how effective stent-grafts are in the treatment of aortic dissections.
The following is a list of sites around the world involved with the International Registry of Acute Aortic Dissection:
University of Michigan Hospital, USA
Washington University Hospital, USA
Mayo Clinic, USA
Minneapolis Heart Institute, USA
University of Pennsylvania Hospital, USA
Brigham & Women's Hospital, USA
Massachusetts General Hospital, USA
University of Massachusetts Hospital, USA
St. Michael's Hospital, Canada
University of Tokyo Hospital, Japan
Tromsø University Hospital, Norway
Hôpital Bichat, France
Robert-Bosch Krankenhaus, Germany
University of Rostock Hospital, Germany
Medical School Graz, Austria
University of Vienna Hospital, Austria
Hospital General Universitari Vall d'Hebron, Spain
Hospital General Universitario "12 de Octubre", Spain
Cardiocentro Ticino, Switzerland
University Hospital S. Orsola, Italy
Istituto Policlinico San Donato, Italy
Hadassah University Hospital, Israel