Athoracic aortic aneurysm is an abnormal widening of the aorta between the aortic valve and the diaphragm. An aneurysm is defined as dilation of the aorta that is more than 150% of its normal diameter for a given segment. A diameter of greater than 3.5 cm is generally considered dilated for the thoracic aorta, whereas greater than 4.5 cm would be considered aneurysmal.
Thoracic aneurysms account for approximately 25% of all aneurysms, and approximately 25% of people with thoracic aneurisms also have abdominal aneurysms. Although aneurysms may be located on the ascending, transverse (aortic arch), or descending part of the aorta or may involve the entire thoracic aorta, they commonly develop between the origin of the left subclavian artery and the diaphragm.
Aneurysm formation is caused by a weakening of the medial layer of the aorta, which stretches outward, causing an outpouching of the aortic wall. Thoracic aortic aneurysms take four forms: fusiform, saccular, dissecting, and false aneurysms (Table 1). Dissection of the aorta can occur with or without an aneurysm but is most often associated with the presence of a preexisting aneurysm. Thoracic aortic aneurysms may lead to serious or fatal complications if they are left untreated. For example, a thoracic dissecting aneurysm may rupture into the pericardium, thus resulting in cardiac tamponade, hemorrhagic shock, and cardiac arrest.
The single most important cause is atherosclerosis. The atherosclerotic process damages the arterial wall by weakening the medial muscle layer and distending the lumen. Destruction of the medial layer allows the artery to increase in size circumferentially (a fusiform shape), or the artery develops a saccular outpouching at the weakened area. Other factors that contribute include Marfan’s syndrome (hereditary musculoskeletal disorder), Ehlers-Danlos syndrome (an inherited disorder of elastic connective tissue), coarctation of the aorta, fungal infections (mycotic aneurysms) of the aortic arch, a bicuspid aortic valve, aortitis, and trauma (external, blunt trauma or iatrogenic trauma that occurs during invasive diagnostic procedures).
Nursing care plan assessment and physical examination
Establish a history of atherosclerosis, hypertension, hypercholesteremia, smoking, obesity, diabetes, and familial tendencies. Elicit a history of pain, including a description and location. Establish a history of pulmonary symptoms, such as wheezing, coughing, hemoptysis, dyspnea, or stridor, which may be caused by a descending thoracic aortic aneurysm that compresses the tracheobronchial tree. Ask if the patient has had difficulties swallowing, hoarseness, dyspnea, or dry cough, all of which may be caused by a transverse arch thoracic aortic aneurysm.
The physical examination of a patient with a thoracic aortic aneurysm does not reveal the presence of the aneurysm itself. Certain physical findings, however, should raise your level of suspicion. Complete a neurological examination to determine the adequacy of tissue perfusion. Take the patient’s blood pressure in both arms because an ascending thoracic aortic aneurysm may cause a contralateral (opposite side) difference. Take both the patient’s right carotid and left radial pulses and note any differences. Auscultate for pericardial friction rub and aortic valve insufficiency murmur, indicating the extension of an ascending aortic aneurysm proximally into the aortic valve. Note any signs of bradycardia.
Assess the patient’s and significant others’ understanding of the implications of the condition. Assess the ability of the patient and significant others to cope with a sudden lifethreatening illness, a prolonged hospitalization, and the role changes that a sudden illness requires. Assess the patient’s level of anxiety about the illness, potential surgery, and complications.
Nursing care plan primary nursing diagnosis: Potential for altered tissue perfusion (cerebral, peripheral, cardiopulmonary, gastrointestinal, renal) related to fluid volume deficit and hemorrhage.
Nursing care plan intervention and treatment plan
A thoracic aortic aneurysm that is 4 cm in size or less may be treated with oral antihypertensives or a beta-blocking agent to control hypertension. Frequent diagnostic testing (every 6 months) is necessary to determine the size of the aneurysm. A thoracic aortic aneurysm that is 5 cm or greater in diameter is usually treated surgically. Other indications for surgical intervention include dissection, intractable pain, and an unstable aneurysm (one that is changing size). The primary complication for thoracic aortic aneurysms is dissection. Monitor the patient for any changes in the quality of peripheral pulses; changes in vital signs; changes in the level of consciousness; and onset of sudden, severe, ripping, or tearing pain in the chest, neck, back, or shoulders. A ruptured thoracic aortic aneurysm requires immediate surgical intervention.
Preoperatively, assess the patient’s peripheral pulses, taking care to compare one side with the other. Take the patient’s blood pressure measurement in both arms, and auscultate for an aortic insufficiency murmur to establish a baseline for postoperative comparison. Also, administer large volumes of intravenous fluids and blood products to maintain circulation until surgery is performed. Surgical procedures vary, depending on the location of the aneurysm. An ascending arch aneurysm may be replaced with an interposition graft, a composite valved conduit, or a supracoronary graft with separate aortic valve replacement. A transverse arch aneurysm is usually repaired with anastomoses and reconstructions. A graft is used to repair descending thoracic and thoracoabdominal aneurysms. Postoperatively, monitor cardiopulmonary states, especially for patients with congestive heart failure (CHF), because beta-blocking agents may worsen CHF. If the patient has hypercholesteremia that cannot be controlled with diet, a cholesterol-lowering agent may be prescribed by the physician.
Focus on maintaining adequate circulation, preventing complications, and implementing patient education. For the nonsurgical patient, patient teaching includes information about low-fat, lowcholesterol diets to prevent progression of the atherosclerotic process and to treat hypercholesteremia. Urge the patient to stop smoking cigarettes and provide information about smoking cessation.
For the surgical patient, focus on maintaining adequate circulation preoperatively and postoperatively, preventing complications, and patient teaching. Preoperative care of the elective
surgical patient is the same as for any patient who undergoes general anesthesia. Postoperatively, care is similar to that of a patient who undergoes any chest surgery. Provide aggressive pulmonary hygiene every 1 to 2 hours to prevent pulmonary complications. Assist with range-ofmotion exercises to limit the effects of immobility. Provide emotional support for the patient and significant others.
Nursing care plan discharge and home health care guidelines
The nonsurgical patient is discharged to the home setting. The surgical patient is usually discharged to the home setting if a support system can be identified. An extended-care facility may be required for a short time if a support system is not in place for the patient at the time of discharge. Be sure the patient understands all medications prescribed, including dosage, route, action, and side effects. Provide patients and their families with information about a low-fat, low-cholesterol diet (reducedcalorie if obese). Be sure the patient understands the importance of controlling blood pressure and blood cholesterol levels in the prevention of progression of the atherosclerotic process.
Provide patients who smoke and their families with information about how to stop smoking. Be sure the patient understands that smoking is a risk factor for hypertension and atherosclerosis. Make sure the nonsurgical patient with a thoracic aortic aneurysm understands the necessity for follow-up examinations at regular intervals to determine the size of the aneurysm and the rate of enlargement. The surgical patient is restricted from activity for 6 to 12 weeks postoperatively. Teach the patient to restrict activities by avoiding heavy lifting, pushing or pulling strenuously, and straining. Give the surgical patient specific instructions for wound care. Teach the patient to examine the incision site for signs of infection and to report any to the physician.