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July 26, 2004

Coding for Aortic Dissection
For the Record
Vol. 16 No. 15 p. 37

Aortic dissection is a tear or damage to the intimal layer of the aorta, which causes bleeding into and along the wall of the aorta. This life-threatening condition usually occurs within the chest in the ascending or descending part of the thoracic aorta, but it may also occur in the abdominal aorta. The physician may document this condition as dissecting aneurysm. Dissecting aortic aneurysm (aortic dissection) is classified to ICD-9-CM code 441.0x. The following fifth-digit subclassification identifies the site of the dissection:

• 441.00, Unspecified site

• 441.01, Thoracic

• 441.02, Abdominal

• 441.03, Thoracoabdominal

Classification Systems
There are two different classification systems used to categorize aortic dissections. The more commonly used system is the Stanford classification, which is divided as follows:

• Type A – defined as involving the ascending aorta and usually requires surgical treatment

• Type B – does not involve the ascending aorta and may be managed medically
The DeBakey classification system is as follows:

• Type I – involves the ascending aorta, aortic arch, and descending aorta

• Type II – confined to ascending aorta

• Type III – confined to the descending aorta distal to the left subclavian artery. Type III is further divided into Type IIIa and Type IIIb depending on how far the dissection extends.

The type of aortic dissection does not affect code assignment. The code assignment is only based on the site of the dissecting aneurysm. (AHA Coding Clinic for ICD-9-CM, 1989, fourth quarter, page 10.)

Causes
The following are some of the most common causes of aortic dissection:

• high blood pressure;

• Marfan syndrome;

• Ehlers-Danlos syndrome;

• blunt force or trauma to the chest;

• atherosclerosis;

• pregnancy;

• valve disorders, including aortic insufficiency;

• coarctation of the aorta;

• syphilis;

• complication of interventional procedures;

• annuloaortic ectasia; and

• adult polycystic kidney disease.

Signs and Symptoms
The following are common signs and symptoms of aortic dissection:

• sudden and severe onset of chest pain that may be described as sharp, stabbing, ripping, or tearing. The pain may be located below the sternum then radiate under the shoulder blades to the back;

• rapid pulse;

• shortness of breath;

• sweating;

• pallor;

• anxiety;

• nausea and vomiting;

• confusion and disorientation;

• decreased movement;

• decreased sensation;

• dry mouth or skin;

• thirst; and

• dizziness and fainting.

The presenting signs and symptoms may be misinterpreted as a myocardial infarction (MI), or it may occur at the same time as an MI if it involves a coronary artery.

Aortic dissection may also result in cardiac tamponade when the dissection involves the pericardial space.

Diagnosis
The physician may choose to perform some of the following diagnostic tests to confirm the diagnosis of aortic dissection:

• chest x-ray – detects mediastinal widening, pleural effusion, or hemothorax;

• echocardiogram;

• transesophageal echocardiogram;

• chest magnetic resonance imaging;

• computed tomography scan of chest with dye;

• aortic angiography;

• Doppler ultrasonography;

• electrocardiogram;

• hematocrit – performed to evaluate blood loss; and

• listening to a stethoscope may reveal a blowing murmur over the aorta.

Treatment
The treatment for aortic dissection depends on the location of the primary tear. If surgical treatment is required, the area of the aorta with the intimal tear is resected and replaced with a graft.

The goal of medical treatment is to reduce pain and the systolic blood pressure and may involve antihypertensive medications, beta blockers, and potent analgesics.

Other Types of Arterial Dissection
Other common sites of arterial dissection include the following:

• Dissection of coronary artery (414.12) – usually caused by a complication of cardiac catheterization, angioplasty, ascending aortic dissection, or coronary bypass surgery

• Dissection of carotid artery (443.21) – may be spontaneous or occurs because of a traumatic event. It may also be caused by Marfan syndrome or fibrocystic dysplasia

• Dissection of iliac artery (443.22) – caused by trauma and Marfan syndrome. It is most commonly a result of a complication of endovascular repair of abdominal aortic aneurysm, nephrectomy, and renal transplant

• Dissection of renal artery (443.23) – caused by hypertension, abrupt onset of proteinuria, abdominal bruits, and renal failure

• Dissection of vertebral artery (443.24) – may be spontaneous or caused by trauma
Coding and sequencing for aortic dissection are dependent upon the physician documentation in the medical record and application of the Official Coding Guidelines for inpatient care. Also, use specific AHA Coding Clinic for ICD-9-CM and American Medical Association CPT Assistant references to ensure complete and accurate coding.

— This information was prepared by Audrey Howard, RHIA, and Vicki Sippel, RHIA, of 3M Health Information Systems (800-367-2447), a leading supplier of coding and classification systems to nearly 4,000 healthcare providers. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payers as the result of the misuse of this coding information.

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