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Endovascular stent-graft repair of descending thoracic aortic aneurysms: The nursing implications for care
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Endovascular stent-graft repair of descending thoracic aortic aneurysms: The nursing implications for care Victoria Latessa, RN, MSN, ANP, ACNP, C
Endovascular repair of descending thoracic aortic aneurysms is a minimally invasive procedure performed with the patient under epidural or spinal anesthesia as an alternative to the conventional left thoracotomy repair. A Dacron graft, similar to the one used in the conventional repair, is placed in the thoracic aorta with fluoroscopic guidance via the femoral or iliac artery. Once the graft is in place, the aneurysm is excluded from the general circulation, thereby preventing rupture. Endovascular repair is currently being offered at selected sites to patients who otherwise would not be candidates for surgical repair due to severe comorbidities such as cardiac, pulmonary, or renal disease. As both the technique and the devices become perfected, endovascular stent-graft repair of descending thoracic aortic aneurysms will most likely be offered as a method of treatment in both high- and low-risk patients who are anatomic candidates for the procedure. This article describes the conventional repair and the endovascular repair of descending thoracic aneurysms. It discusses the implications for nursing care in the preoperative and postoperative settings and defines guidelines for the long-term follow-up of patients who undergo endovascular repair. (J Vasc Nurs 2002;20:86-93)
Descending thoracic aortic aneurysms (DTAA), located below the left subclavian artery and above the celiac artery, represent a formidable health problem (Figure 1). Although the majority of DTAA are asymptomatic, all are potentially lifethreatening because the natural course of DTAA is progressive dilatation with ultimate rupture.1,2 Ninety percent of ruptures result in death.1-3 There is no known medical treatment for DTAA and, up until recently, the only known treatment was left thoracotomy and replacement of the aorta with prosthetic graft. The operative mortality for this procedure is approximately 10%.2 Alternatively, the average 3-year survival rate for patients with untreated DTAA is less than 25%.3-5 Therefore, most physicians recommend surgical repair once the aneurysm reaches 6 cm. Unfortunately, the patients who have DTAA frequently have comorbidities such as chronic obstructive lung disease (COPD), coronary artery disease (CAD), or renal insufficiency that sometimes complicate conventional repair.6,7 Endovascular repair of DTAA provides an alternative to conventional repair. A stent-graft consists of a prosthetic Dacron or polytetrafluoroethylene graft attached to a stent. This stentgraft is then compressed and inserted into a slender tubular sheath, which can be passed over a guide wire and maneuvered From Mount Sinai Medical Center, New York, New York. Reprint requests: Victoria Latessa, RN, MSN, ANP, ACNP, C, Mount Sinai Medical Center, 5 E 98th St, Box 1259, New York, NY 10029. Copyright © 2002 by the Society for Vascular Nursing, Inc. 1062-0303/2002/$35.00 ⫹ 0 40/1/127736 doi:10.1067/mvn.2002.127736
up the femoral or iliac artery into the thoracic aorta with fluoroscopic guidance. The procedure is performed with the patient under spinal or epidural anesthesia. The technique is similar to that used for balloon angioplasty and stenting of coronary artery blockages. Retraction of the sheath allows the self-expanding stent to expand, seating the graft against the aortic wall. Once the endovascular graft is deployed, it provides a conduit for bloodflow and excludes the aneurysm sac from the general circulation, thereby preventing rupture. Endovascular stent-graft repair (EVSG) of DTAA not only represents an exciting method of treating aneurysms but will demand new and challenging skills from the nurses involved in the care and treatment of patients undergoing this procedure. This type of repair also provides an opportunity for nurses to work collaboratively with physicians to provide optimum care and patient education. This article describes and compares the conventional and endovascular repair of DTAA. It further describes the unique complications that can occur with the endovascular procedure and discusses the nursing implications for both the general and advanced practice nurse in the perioperative arena as well as in long-term follow-up.
INCIDENCE The estimated annual incidence of thoracic aortic aneurysm is 6 cases per 100,000 people; of those cases, only 40% will be located in the descending thoracic aorta.5 Although the incidence is low, the number of people diagnosed with DTAA is thought to be increasing. Factors believed to contribute to this possible rise include increased longevity of the population and improved diagnostic capability.3 There is also a familial incidence of aortic aneurysm. The risk of abdominal aortic aneurysms among first-degree relatives of aneurysm patients is 6 times that of the general population.
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Other less common causes of DTAA include trauma, infection, inflammation, and connective tissue disorder. DTAA also can be congenital or occur as a result of an aortic dissection.13
SIGNS AND SYMPTOMS The majority of thoracic aneurysms are asymptomatic and are discovered incidentally while other health problems are being investigated; only 20% cause symptoms.1-3 Some symptoms are produced as a result of the aneurysm pressing on adjacent structures, resulting in dysphagia, shortness of breath due to compression on the trachea, hoarseness due to left laryngeal nerve compression, or hemoptysis if the aneurysm erodes into the bronchus.8,14 Back pain can occur if the aneurysm erodes into a vertebral body. Chest pain can occur from aneurysmal expansion with resultant pressure or stretching.7 Rarely, patients present with signs of distal embolization of the lower extremities from a thrombus-filled thoracic aneurysm. Some patients present with a ruptured thoracic aneurysm, which is characterized by sudden onset of severe back or chest pain, hypotension, and cardiovascular collapse.8 The physical examination for thoracic aneurysm is usually nondiagnostic. Occasionally, a pulsatile mass can be palpated in the epigastric or supraclavicular region. Rarely, a left supraclavicular or paravertebral bruit can be heard, but diagnosis of thoracic aneurysm must be confirmed with radiologic studies.1 Even though thoracic aneurysm may sometimes cause widening of the mediastinum, which is demonstrated on chest x-ray, this is often misread as simple tortuosity of the aorta and is nondiagnositc.4 One should have a high level of suspicion when evaluating patients with multiple risk factors for aneurysm, such as smoking, hypertension, hyperlipidemia, and first-degree relatives with an aortic aneurysm. Not only is aneurysm formation familial, it is a systemic disease.8 Patients can also present with more than 1 aneurysm. Figure 1. Descending thoracic aortic aneurysm.
CONVENTIONAL LEFT THORACOTOMY REPAIR OF DTAA
Concomitantly, 25% to 30% of people with abdominal aortic aneurysms will develop thoracic aneurysms.8
For the past 40 years, patients have undergone conventional repair of DTAA, and it remains the gold standard. Unfortunately, the procedure involves prolonged general anesthesia with placement of a specialized bifurcated endotracheal tube and transesophageal probe to monitor cardiac activity throughout the procedure. Multiple intravenous lines are placed into various large vessels for continuous monitoring throughout the procedure. Typically, a Swan-Ganz catheter is inserted by the anesthesiologist. Also, a radial arterial line and 1 or 2 peripheral large-bore catheters are placed for rapid infusion of blood and intravenous fluids. In our institution, a spinal catheter is placed in the subarachnoid space at the L4-5 intervertebral level and advanced up to the T12-L1 level. This catheter will remain in place for 48 to 72 hours postoperatively as an adjunct in reducing spinal cord ischemia. Cerebrospinal fluid (CSF) drainage is thought to promote spinal cord artery bloodflow by decreasing the CSF pressure that accompanies reperfusion. Anesthesia preparation time for this procedure is 1 to 2 hours.15 Once the patient is intubated and the invasive lines have been placed, a left thoracotomy is performed, the left lung is deflated for exposure, and the aorta is cross-clamped while the graft is
ETIOLOGIC FACTORS Historically, more than 80% of all thoracic aneurysms were attributed to syphilis; however, with the advent of antibiotics, this infectious disease now comprises fewer than 5% of patients with thoracic aneurysms.8 Atherosclerosis, a degenerative disease of the arterial system, accounts for 80% of the aneurysms found in the thoracic aorta.8 Patients with aneurysmal dilation have an elevation of elastolytic enzymes that cause fragmentation of the supporting elements of the aortic wall. The degenerative structural change within the muscular, elastic, and collagen fibers of the aortic wall produces a weakness in the wall of the aorta that leads to progressive dilation and subsequent aneurysm formation.9 Known factors that will contribute to aneurysm growth are uncontrolled hypertension by virtue of the increased pressure in the aneurysm sac and the continued use of tobacco.10 The by-products of smoking promote the breakdown of the collagen matrix, which is one of the supporting structures of the aortic wall.11,12
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Figure 2. A, DTAA and EVSG before graft deployment. B, DTAA and EVSG after graft deployment.
sewn in place. During this time, the bloodflow to the visceral vessels (celiac, superior, and inferior mesenteric arteries) and the renal arteries is interrupted. There is also interruption of the bloodflow from the intercostal arteries to the spinal cord during cross-clamping of the aorta. Some surgeons may use a shunt or place the patient on bypass during this part of the procedure to provide bloodflow to the viscera and lower extremities. Patients often require blood replacement. The average length of time in the operating room is 6 hours. Complications include prolonged ventilatory support, paraplegia, renal failure, left ventricular failure, ischemic bowel, and coagulopathies.2,3 Mortality rates average 5% to 10%, and morbidities can be as high as 40%.2,13 Patients are hospitalized for 7 to 14 days, barring any complications and are discharged home with family members or with medical assistance, such as a visiting nurse or physical therapist. Occasionally, patients will require a 1- to 2-week stay in a rehabilitation facility to gain strength and endurance. The recuperative period is usually 6 to 12 weeks before patients return to baseline.
ENDOVASCULAR STENT-GRAFT REPAIR OF DTTA Because these devices are still investigational, all of the patients are prepared according to strict Federal Drug Administration protocols. At Mount Sinai Hospital in New York, EVSG repair is done in the operating room with the patient under epidural anesthesia. The patient is positioned supine on a fluoroscopy table. Light sedation is given so that patients can comfortably tolerate lying still for the 1 to 2 hours necessary for
the procedure. Nasal oxygen is given by cannula at 2 to 3 L/minute. A jugular central venous pressure line is inserted as well as a radial arterial line and a peripheral intravenous line. Oxygenation is monitored with pulse oximetry. A Foley catheter is inserted. Peripheral pulses are palpated and marked. The abdomen, pelvis, and groins are prepared. A prophylactic dose of antibiotic is given intravenously. Next, the access vessel, usually the iliac or femoral artery, is exposed via cutdown. The patient is given heparin, and a protective sheath is introduced into the access vessel. The sheath acts as a protective device for the artery providing a conduit through which all instrumentation takes place. A guide wire is introduced into the aorta, followed by the delivery system that houses the endovascular stent-graft. Before the device can be deployed, patients are given a dose of the beta-blocker and a vasodilator to decrease the mean arterial pressure to 50 to 60 mmHg. This results in decreased bloodflow to prevent downward migration of the stent during the critical moment of deployment of the graft. After successful placement of the graft, a completion angiogram is performed to ensure proper positioning of the endoluminal graft and the absence of endoleak (Figure 2 A and B). An endoleak refers to the continued perfusion of the aneurysm sac after placement of the stent-graft.16 There are different types of endoleaks (Table 1). Ideally though, at this point in the procedure, the aneurysm should be excluded from the general circulation and all bloodflow should now go through the graft. Next, heparinization is reversed with protamine, the introducer sheath is removed, and the arteriotomy is closed. The
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TABLE I CLASSIFICATION OF ENDOLEAKS Type Type Type Type
I: Proximal or distal attachment site leak II: Retrograde flow from patent intercostal arteries III: Fabric tears, disintegration of graft IV: Graft porosity
J Endovasc Surg 1998;5(4):305-9.
patient is transferred to the postanesthesia care unit for an overnight stay. The following day, the patient is transferred to a regular surgical floor for continued observation and mobilization. Discharge is usually on the third or fourth postoperative day.
SCREENING FOR ENDOVASCULAR STENTGRAFT REPAIR Candidacy for endovascular repair to DTAA is dependent on patient anatomy.14 One of the primary considerations is a sufficient amount of normal aorta above and below the aneurysm in which to secure the device since the attachment to the aortic wall is by lateral wall pressure from the stent part of the stent-graft. Technically, this area is referred to as the proximal and distal neck, respectively. Most devices require at least a 2-cm area below the left subclavian artery and 2 cm above the celiac artery.3,7 In some cases, if the proximal neck is inadequate, a subclavian transposition can be performed before EVSG to obtain a more usable aortic neck.14 The proximal and distal necks are also vitally important since the prosthetic device must fit securely up against the aorta to form a tight seal once in place to exclude the aneurysm from the general circulation. Thrombus in this region may result in an unstable landing zone, increasing the likelihood of migration of the graft and possible endoleak. The second anatomic consideration is that of the access vessels. An endovascular device must be inserted into the iliac or femoral artery and navigated up into the thoracic aorta. The diameter of the access vessel has to be large enough to accommodate a device that may be as large as a 24 to 27 French catheter or 8 to 9 mm in diameter.17 Tortuous, calcified, stenotic arteries make access difficult and dangerous, increasing the risk of injury to the artery. The following 2 diagnostic tools are used to evaluate patients for EVSG: spiral computed tomography (CT) scan and an angiogram. The spiral CT scan is done with intravenous contrast and 3-mm cuts. Views need to include the chest, abdomen, and pelvis so that the aneurysm and the access vessels can be visualized. The CT scan is used to determine vessel diameter in calculating the diameter of the EVSG. The angiogram is done with a radiopaque marker catheter labeled in 1-cm increments so that the length of the EVSG can be determined with measurements obtained from the angiogram. The angiogram also provides important information regarding the patency of visceral vessels and intercostal arteries. The measurements taken from
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these 2 radiologic studies help to ensure accurate sizing of the endovascular device.17
Advantages There are many advantages to endovascular repair of DTAA (Table 2). The most important advantage is that it provides a treatment modality for many patients who otherwise would not be candidates for conventional repair because of their comorbidities. Other advantages include decreased length of hospital stay, shorter recuperation, and a decrease in mortality and morbidity for a category of high-risk patients.
Complications in EVSG repair and their implications for nursing Endovascular repair has brought about a unique subset of complications inherent to this new technology. Optimal postoperative care cannot be given without the professional nurse knowing the signs and symptoms of these complications and possessing the assessment skills to rapidly evaluate and institute the proper measures to expedite treatment. Endoleak is the most common complication associated with EVSG repair (Figure 3).3,5,17 It refers to the continued perfusion of the aneurysm sac after placement of the graft. This is due to a poor proximal or distal seal, patent intercostal arteries that continue to perfuse the aneurysm, ineffective seal between devices if more than 1 device was used, or device failure. Endoleaks may also occur as a result of upward or downward migration.17 This is thought to occur as the morphology of the aneurysm sac shrinks in response to exclusion by the endoluminal graft.17 Endoleaks can occur in the early postoperative period or later in long-term follow-up, thus careful follow-up of these patients is mandatory.16 As with open repair, paraplegia can occur.17 Even though the endovascular approach avoids spinal cord ischemia due to crossclamping, there is still a risk of spinal cord injury due to occlusion of intercostal arteries covered by the endograft. Time is of the essence because the duration of cord ischemia is the most important factor in the onset of paraplegia.18 Placement of CSF drainage postoperatively, if implemented early, has been shown in selected cases to alleviate this problem by allowing for improved collateral circulation to the spinal cord.18,19 Embolic stroke is a complication that can occur as a result of the passage of guide wires and instruments at the level of the aortic arch. Embolization can also occur into visceral and renal arteries, resulting in ischemic bowel or kidney. Microemboli can also travel downstream, resulting in ischemic changes of the lower extremities. Postimplantation syndrome is occasionally seen and typically begins within 24 hours of stent-graft placement. This syndrome consists of a spontaneously resolving fever, leukocytosis, and occasionally, transient thrombocytopenia. Although the exact etiologic factor is unknown, the symptoms are thought to be related to activation of cytokines that results from thrombosis in the excluded aneurysm with the release of coagulation proteins and platelets.20 Usually, these symptoms can be managed with mild analgesics or anti-inflammatory agents such as acetaminophen or ibuprofen. The symptoms usually subside within 1 week.
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TABLE II COMPARISON OF CONVENTIONAL REPAIR VERSUS ENDOVASCULAR REPAIR OF DATA EVSG repair Surgical procedure Anesthesia Limitations Blood loss Paraplegia Hospital stay Recuperation Follow-up Long-term durability Mortality
Groin incision Epidural/spinal Anatomy Minimal 3% 3-4 days 7-10 days Every 3-6 months for 1 year, then annually Unknown 10%
Conventional Thoracotomy General Comorbidities 6-8 units 3%-15% 7-14 days 6-12 weeks Annually Lifetime guarantee 10%
thoracic grafts are rigid and must be navigated through sometimes tortuous, calcified, stenotic iliac and femoral arteries and have the potential for injury. Other insertion site complications include hematoma, lymphocele, pseudoaneurysm, and wound infection.17
NURSING IMPLICATIONS Nurses play a key role in the management of EVSG patients. They are often the first person contacted or the first person available to assess and evaluate patients both before surgery and postoperatively. Therefore, nurses need to be knowledgeable about the procedure itself and the complications that can ensue. Accurate assessment is vital.
Preoperative nursing implications Figure 3. CT scan of chest with endoleak. Arrow, Endoleak contrast in aneurysm sac.
It is quite common for patients to develop a pleural effusion after EVSG repair of the thoracic aneurysm. An inflammatory reaction of the aortic wall occurs as a result of the pressure of the stent-graft on the aorta and the thrombosis of blood in the excluded aneurysm sac. Occasionally, the effusion can become quite significant and cause shortness of breath, requiring thoracentesis to relieve the symptom. The effusion may recur over a few weeks and may require repeated drainage.21 Some patients may report the sudden onset of chest and back pain a few days after EVSG repair. Obviously, myocardial infarction or device failure with rupture of the aneurysm must be ruled out, but a frequent cause is delayed thrombosis of the intercostal arteries and resultant pain from ischemia of the paraspinal muscles. The continued flow into the aneurysm sac can cause pain from the inflammatory response of the paraspinal muscles. In some patients, this may persist for 1 week or more. Lastly, local complications can occur as a result of injury to the access vessel. These include laceration, rupture, or thrombosis of the femoral or iliac artery. The large delivery systems for
Patients usually come to the office of the vascular surgeon in a panic after having been told they have a thoracic aneurysm. First and foremost, establish rapport with patients by listening intently and offering reassurance. Put patients at ease by focusing on early diagnosis and safe repair before rupture. Next, obtain a thorough history. Note any complaints that might indicate the thoracic aneurysm is symptomatic such as unexplained chest or back pain, dysphagia, shortness of breath, hoarseness, or signs of distal embolization. A thorough arterial assessment with specific attention to the abdomen and both popliteal fossa should be performed to detect evidence of aneurysm formation elsewhere. Also, a medical evaluation is necessary to identify other risk factors that might affect perioperative morbidity. Once eligibility for EVSG repair is determined, informed consent must be obtained by the physician or a designated person from the research team. Informed consent requires that the patient have a full understanding of that to which he or she has consented. This means that patients need to be informed of all options, including observation; left thoracotomy; open repair, if the patient is a surgical candidate; and endovascular repair. Pictures and diagrams are extremely helpful in explaining the
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procedures and should be available. Patients should understand that EVSG repair is currently considered investigational and that the Federal Drug Administration requires long-term follow-up. Next, to prepare the patient and his or her family for the anticipated surgery, the nurse should review preoperative testing, the operative procedure, and the anticipitated postoperative course for the institution. This information will allow patients and families to plan accordingly for hospitalization and recuperation. Once it is determined that the patient will undergo the procedure, laboratory studies (eg, complete blood count, prothrombin time, partial thromboplastin time, and platelet count and electrolyte, blood urea nitrogen, creatinine, and glucose levels) are obtained. A chest radiograph, electrocardiogram, cardiac evaluation with stress test, CT scan of the chest abdomen and pelvis, and an angiogram with marker catheter are also necessary. One must be aware of and proceed with caution with patients who have renal insufficiency. The patient should be well hydrated, and acetylcysteine or fenoldopam is frequently used as a renal protective agent.22,23 For patients allergic to contrast, steroids and diphenhydramine (Benadryl) are given before the procedure.
Postoperative nursing implications Nurses caring for EVSG patients should be knowledgeable about the EVSG procedure and the possible complications that could ensue. Subtle changes in physiologic parameters can lead to disasters if not acted upon immediately. The patient’s appearance can be quite misleading since patients are insensate from the waist down because of epidural anesthesia. Upon admission to the postanesthesia care unit (PACU), blood pressure measurements need to be taken in both arms. A graft placed too high in the aorta, partially or totally occluding the left subclavian artery, would produce a low or absent blood pressure reading in the left arm. Document the presence or absence of pulses in both the upper and lower extremities as well as any pressure differences, and inform the surgeon promptly if any symptoms occur because further intervention may need to be taken immediately. The access site for the introduction of the graft is usually the iliac or femoral artery, so the insertion site should be assessed for the presence of pulsation, bleeding, or hematoma formation. Also, note distal pulses and skin changes of the lower extremities, posterior thorax, lumbar area, or buttocks that might indicate signs of embolization, such as irregular-shaped, cyanotic areas that are exquisitely tender. Neurologic evaluations are of utmost importance. Embolic stroke and paraplegia are known complications. Embolic stroke can cause a change in vital signs, such as visual changes, aphasia, alteration in the level of consciousness, changes in mentation, or sensory or motor loss in the extremities.24 Most institutions have standardized neurologic assessment forms that should be used throughout the patient’s hospital stay. Close observation and accurate documentation help to determine the area of the brain or the level of the spinal cord that is affected. Paraplegia can occur secondary to spinal cord ischemia. The ischemic changes that occur can result in mild paresis or paralysis of the extremities. Patients have had epidural anesthetics and
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are insensate in the immediate postoperative period; therefore, observation and frequent neurologic examinations are critical. The nurse should note the return of lower extremity sensation and motor ability with the appropriate muscle strength. If any sign of paresis or paralysis develops, the physician should be notified immediately because spinal drainage may be implemented and in some cases can completely reverse this complication. Embolization can occur to visceral vessels as well as renal arteries; therefore, the abdominal examination is an essential part of the assessment. Signs and symptoms of acute mesenteric ischemia are usually sudden and dramatic. Acute abdominal pain is accompanied by vomiting or bowel movement or both. Patients complain of intense pain, but the abdomen is usually soft and minimally tender to palpation.25 These symptoms require urgent diagnostic testing and intervention. Embolization to the renal artery can also result in severe abdominal or flank pain and can impair renal function. A Foley catheter is routinely inserted at the onset of the procedure and remains for 24 hours postoperatively to measure urinary output. Blood urea nitrogen and creatinine levels are also monitored frequently because patients receive a significant volume of contrast intraoperatively to ensure proper placement of the EVSG. The patient’s temperature should be monitored every 4 hours, and any signs and symptoms of a post-implantation syndrome should be noted. Fever that persists after 14 days warrants further investigation to eliminate any possible source of infection. Lastly, patients who develop back or chest pain after the procedure should be re-evaluated by the cardiology department. Once it is determined that the source of the discomfort is not cardiac in origin, CT scan of the chest is obtained to look for an endoleak. If no endoleak is found, the patient can be safely monitored by following-up on the character and severity of the pain. The pain should not increase, and the character should not change, other than to improve. At Mount Sinai Hospital, all endovascular patients receive standardized, home-going instructions that detail activity, wound care, diet, medications, continued medical care, and instructions for follow-up appointment. Also listed are warnings and precautions for symptoms that may warrant immediate medical attention and the 24-hour telephone number where a member of the endovascular team can be reached. The patient’s primary care nurse reviews the instructions with the patient at the time of discharge.
Long-term surveillance One of the salient factors in determining whether a patient should have an EVSG is the unknown long-term durability of the graft itself and its ability to maintain proper position over time since the structure of the native aorta is subject to change. The aneurysm sac can shrink in response to exclusion by the EVSG or in isolated cases can continue to increase. These changes can distort the proximal and distal landing zones and predispose the patient to endoleak. Therefore, patients with EVSG repair will require lifetime follow-up. Those providing long-term follow-up
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TABLE III WARNINGS/PRECAUTIONS Please notify our office immediately if you experience any of the following: 1. Fever more than 101° F or 39° C 2. Redness, increased swelling, drainage, or bleeding from groin incisions 3. Severe or unusual chest, back, or abdominal pain 4. Severe or unusual arm or leg pain or weakness 5. Numbness and tingling of arm or leg 6. Unusual shortness of breath or difficulty with breathing 7. Dizziness, sudden weakness
and telephone triage must be constantly aware of both the subtle and obvious symptoms that may signal a problem. After discharge from the hospital, patients are scheduled for an office visit in 7 to 10 days. The postoperative spiral CT scan with intravenous contrast and 3-mm cuts is done at this time rather than in the hospital because dye can be retained in the aneurysm sac from the original procedure and give a false impression of endoleak. A 4-view chest x-ray is obtained (ie, anteroposterior, lateral, right, and left oblique views). The chest x-ray is reviewed for fracture of the struts of the EVSG, pleural effusion, and graft migration. During the postoperative office visit, the patient is carefully examined and vital sign measurements, bilateral arm blood pressure readings, and palpation of brachial and radial pulses are documented. Heart and lung fields are auscultated. Abdominal examination is performed, and the groin wound is inspected. Lower extremities are evaluated for signs of embolization; the presence or absence of distal pulses is also noted. Barring any abnormalities, the patient will return for postoperative checkups every 6 months. If an endoleak is discovered and the size of the aneurysm sac remains stable or decreases as measured on CT scan, no intervention is needed. If, however, an endoleak is discovered and the aneurysm sac increases more than 5 mm, the endoleak is identified via angiogram and the vessel perfusing the sac is coiled to prevent further flow. If the endoleak is due to graft migration, an insufficient proximal or distal seal, or a leak between the pieces of the EVSG, another piece of EVSG can sometimes be telescoped into place. Patients are followed-up every 6 months. Late complications do occur, and it is vital for the nurse to review the warning signs and symptoms that prompt immediate investigation at each patient visit (Table 3). Patients are strongly urged to keep the home-going instruction sheet as a handy reference. It lists a 24-hour telephone number in case of emergency. Because our general knowledge and experience with thoracic grafts are still growing, all patient complaints are treated seriously. Any new onset of back, chest, or leg pain or any extremity pain, weakness, numbness, tingling, or change in temperature warrants immediate investigation.
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FUTURE IMPLICATIONS The future of endoluminal repair of thoracic aneurysms is extremely exciting. Nurses caring for patients with endovascular repair of DTAA have the opportunity to be on the cutting edge of rapidly advancing technology. This minimally invasive surgery has the potential to be performed with increasing frequency because of more training programs for physicians, increased availability of devices, improvement in devices and delivery systems, and patient demand. The indications are expanding, and use now includes selected cases of trauma, penetrating ulceration of the aorta, acute dissection, and aortocaval fistula.26-28 The thoracic devices are also used in combination with standard surgical procedures, such as an open repair of abdominal aortic aneurysm followed by EVSG repair of a coexisting thoracic aneurysm. Nurses need to respond and embrace this innovative approach to repairing thoracic aneurysms for patients who previously had no alternative to conventional repair. As technology improves and the patients’ involvement in making their own health care decisions increases, so will the demand for endovascular repair. The advanced practice nurse needs to educate patients, nurses, and other health care providers. To do this, one must keep abreast of the changes in technology. Most importantly, nursing must develop a body of knowledge relative to the physical and emotional responses to this procedure to better provide optimal, holistic nursing care. Last but not least, as health care providers, the risk factors for atherosclerotic disease and aneurysm must be addressed. Patients at high risk for developing aortic aneurysm must be identified and viewed with a high level of suspicion. Hypertension and smoking cessation must be urged more aggressively. Guidelines for screening high-risk patients need to be developed and implemented.
REFERENCES 1. Bickerstaff LK, Pairolero PC, Hollier LH. Thoracic aortic aneurysms: a population based study. Surgery 1982; 92:1103-8. 2. Crawford ES, DeNate RW. Thoracoabdominal aortic aneurysm: observations regarding natural course of disease. J Vasc Surg 1986;3:578-82. 3. Temudom T, D’Ayala M, Marin ML, Hollier LH, Parsons R, Teodorescu V, et al. Endovascular grafts in the treatment of thoracic aortic aneurysms and pseudoaneurysms. Ann Vasc Surg 2000;14:230-8. 4. Hollier LH, Hamilton IH. Thoracoabdominal aortic aneurysms In: Moore WS, editor. Vascular surgery: a comprehensive review. Philadelphia: WB Saunders; 1998. p. 41733. 5. Mitchell RC, Miller DC, Dake MD. Stent-graft repair of thoracic aneurysms. Semin Vasc Surg 1997;10:257-71. 6. Greenberg R, Risher W. Clinical decision making and operative approaches to thoracic aortic aneurysms. Surg Clinics North Am 1998;78:805-25. 7. Ehrlich M, Grabenwalger M, Cartes-Zumelzu F. Endovascular stent graft repair for aneurysms of the descending thoracic aorta. Ann Thorac Surg 1998;66:19-25.
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8. Fann JI, Miller DC. Descending thoracic aortic aneurysm. In: Baul AE, Gena AS, Hammond GL, Laks H, Nauaheim KS, editors. Glenn’s thoracic and cardiovascular surgery. Stanford: Appleton & Lange; 1995. p. 2255-72. 9. Fann JI, Miller DC. Endovascular treatment of descending thoracic aortic aneurysms and dissections. Surg Clinics North Am 1999;79:551-73. 10. McKinsey JF, Graham A, Gerwertz S. Diseases of the vascular system. In: Lawrence P, editor. Essentials of general surgery. Philadelphia: Lippincott, Williams & Wilkins; 2000. p. 435-59. 11. D’Ayala M. Grafting for thoracic aortic aneurysms. In: Marin ML, Hollier LH, editors. Advanced treatment for vascular disease. New York: Futura; 2000. p. 95-107. 12. Tilson MD, Hingorini AP, Grogory AK. Pathogenesis of aneurysms. In: Greenfield LJ, Mulholland MW, Oldham KT, Zelenock GB, Lillimore KD, editors. Essentials of surgery: scientific principles of practice. Philadelphia: LippincottRaven; 1997. 13. Rehm JP, Grange JJ, Baxter BT. The formation of aneurysms. In: Rutherford RB, editor. Seminars in vascular surgery. Philadelphia: WB Saunders; 1997. p. 193-202. 14. Fann JL, Slonim SM, Miller DC. Endovascular treatment of thoracic aortic aneurysms and dissections. In: Calligaro KD, Dougherty MJ, Hollier LH, editors. Diagnosis and treatment of aortic and peripheral arterial aneurysms. Philadelphia: WB Saunders; 1999. p. 97-112. 15. Gravereaux EC, Faries PL, Burks JA, Latessa VR, Spielvogel D, Hollier LH, et al. Risk of spinal cord ischemia after endograft of thoracic aortic aneurysms. J Vasc Surg 2001; 34:997-1003. 16. Dietch JS, Yano OJ. Description and classification of endoleaks. In: Marin ML, Hollier LH, editors. Endovascular grafting: advanced treatment for vascular disease. Armonk (NY): Futura; 2000. p. 133-45. 17. Fann JL, Dake MD, Mitchell RS, Semba CP, Miller DC. Endovascular management of descending thoracic aortic aneurysms. In: Parodi JC, Veith FJ, Marin ML, editors. Endo-
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vascular grafting techniques. Baltimore: Lippincott, Williams & Wilkins; 1998. p. 2255-71. 18. Tiesenhausen K, Amann W, Koch G, Hausegger KA, Oberwalder P, Rigler B. Cerebrospinal fluid drainage to reverse paraplegia after endovascular thoracic aortic aneurysm repair. J Endovasc Therapy 2000;7:132-5. 19. Bethel SA. Use of lumbar cerebrebrospinal fluid drainage in thoracoabdominal aneurysm repairs. J Vasc Nurs 1999;17: 53-8. 20. Jenson C. Stent grafts. In: Eton D, editor. Vascular disease: a multispecialty approach to diagnosis and management. Georgetown (TX): Landes Bioscience; 1999. p. 252-83. 21. Martin GH, O’Hara PJ, Hertzer NR, Mascha EJ. Surgical repair of aneurysms involving the suprarenal, visceral and lower thoracic aortic segments: early results, late outcomes. J Vasc Surg 2000;31:851-61. 22. Safirstein R, Andrade L, Vieria JM. Acetylcysteine and nephrotoxic effects of radiographic contrast agents—a new use for an old drug. N Engl J Med 2000;343:210-2. 23. Singer IE. Potential of dopamine A-1 agonists in the management of acute renal failure. Am J Kidney Dis 1998;31: 743-55. 24. Bradley M, Pearce WH. Extracranial vascular disease. In: Fahey V, editor. Vascular nursing. Philadelphia: WB Saunders; 1999. p. 270-90. 25. Abdessalam S, Baxter BT. Mesenteric ischemia. In: Fahey V, editor. Vascular nursing. Philadelphia: WB Saunders; 1999. p. 330-9. 26. Lobato AC, Quick RC, Philips B, Vranic M, Lopez JR, Douglas M. Immediate endovascular repair for descending thoracic aortic transection due to blunt trauma. J Endovasc Therapy 2000;7:16-20. 27. Umsheid T, Stelter WJ. Endovascular treatment of an aortic aneurysm rupture into the inferior vena cava. J Endovasc Surg 2000;7:31-5. 28. Biasi GM. Aortocaval fistula: a challenge for endovascular management. J Endovasc Surg 1999;6:378.
WRITING AWARD The Journal of Vascular Nursing Article Award honors nurse authors for their efforts to create a publishable manuscript. Manuscripts will be judged for accuracy of content, relevance to vascular nursing practice, and excellence of writing style. All feature articles published in the Journal of Vascular Nursing during the calendar year will be considered for the JVN Article Award. The award recipient will be given a plaque commemorating the award and a cash prize donated by Mosby. The award and cash prize will be presented at the annual symposium. Announcement of the award recipient will appear in the Journal of Vascular Nursing and in SVN...prn.
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Stent graft repair Contact Hours: 1.0 Test ID: JVN0291
Minimum Passing Score: 70% Test Processing Fee: $10.00
OBJECTIVES:
1. Describe the incidence and etiology of DTAA. 2. Identify repair of DTAA. 3. Discuss nursing implications in caring for DTAA patients. 1. What is the risk of abdominal aortic aneurysms (AAA) to primary relatives of aneurysm patients? a. Twice as great b. Four times as great c. Six times as great d. Ten times as great
6. What is the most common complication of endovascular stent graft repair? a. Endoleak b. Paraplegia c. Stroke d. Pleural effusion
2. Of those patients with AAA, what percentage will develop thoracic aneurysms? a. 10%–15% b. 25%-30% c. 45%-50% d. 60%– 65%
7. If the graft were to occlude the subclavian artery, what would be observed? a. Bounding pulses b. Low or absent BP in left arm c. Hypertension d. Weak hand grips
3. Which is the most common cause of thoracic aneurysms? a. Atherosclerosis b. Congenital c. Infection d. Trauma 4. What percentage of thoracic aneurysms are symptomatic? a. 10% b. 20% c. 30% d. 40% 5. A risk factor not associated with possible aneurysm is? a. Smoking b. Hypertension c. Hyperlipidemia d. Diabetes
8. Reversing complications of paraplegia postoperatively can be done with: a. Additional surgery b. Corticosteroid therapy c. Spinal drainage d. Repositioning of the stent 9. Acute abdominal pain with vomiting or bowel movement may be indicative of: a. Embolization b. Poor analgesia control c. Infection d. Stent misplacement 10. Fabric tears and disintegration of the graft is considered a Type __ endoleak. a. I b. II c. III d. IV
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Endovascular stent-graft repair of descending thoracic aortic aneurysms: The nursing implications for care Victoria Latessa, RN, MSN, ANP, ACNP, C
Endovascular repair of descending thoracic aortic aneurysms is a minimally invasive procedure performed with the patient under epidural or spinal anesthesia as an alternative to the conventional left thoracotomy repair. A Dacron graft, similar to the one used in the conventional repair, is placed in the thoracic aorta with fluoroscopic guidance via the femoral or iliac artery. Once the graft is in place, the aneurysm is excluded from the general circulation, thereby preventing rupture. Endovascular repair is currently being offered at selected sites to patients who otherwise would not be candidates for surgical repair due to severe comorbidities such as cardiac, pulmonary, or renal disease. As both the technique and the devices become perfected, endovascular stent-graft repair of descending thoracic aortic aneurysms will most likely be offered as a method of treatment in both high- and low-risk patients who are anatomic candidates for the procedure. This article describes the conventional repair and the endovascular repair of descending thoracic aneurysms. It discusses the implications for nursing care in the preoperative and postoperative settings and defines guidelines for the long-term follow-up of patients who undergo endovascular repair. (J Vasc Nurs 2002;20:86-93)
Descending thoracic aortic aneurysms (DTAA), located below the left subclavian artery and above the celiac artery, represent a formidable health problem (Figure 1). Although the majority of DTAA are asymptomatic, all are potentially lifethreatening because the natural course of DTAA is progressive dilatation with ultimate rupture.1,2 Ninety percent of ruptures result in death.1-3 There is no known medical treatment for DTAA and, up until recently, the only known treatment was left thoracotomy and replacement of the aorta with prosthetic graft. The operative mortality for this procedure is approximately 10%.2 Alternatively, the average 3-year survival rate for patients with untreated DTAA is less than 25%.3-5 Therefore, most physicians recommend surgical repair once the aneurysm reaches 6 cm. Unfortunately, the patients who have DTAA frequently have comorbidities such as chronic obstructive lung disease (COPD), coronary artery disease (CAD), or renal insufficiency that sometimes complicate conventional repair.6,7 Endovascular repair of DTAA provides an alternative to conventional repair. A stent-graft consists of a prosthetic Dacron or polytetrafluoroethylene graft attached to a stent. This stentgraft is then compressed and inserted into a slender tubular sheath, which can be passed over a guide wire and maneuvered From Mount Sinai Medical Center, New York, New York. Reprint requests: Victoria Latessa, RN, MSN, ANP, ACNP, C, Mount Sinai Medical Center, 5 E 98th St, Box 1259, New York, NY 10029. Copyright © 2002 by the Society for Vascular Nursing, Inc. 1062-0303/2002/$35.00 ⫹ 0 40/1/127736 doi:10.1067/mvn.2002.127736
up the femoral or iliac artery into the thoracic aorta with fluoroscopic guidance. The procedure is performed with the patient under spinal or epidural anesthesia. The technique is similar to that used for balloon angioplasty and stenting of coronary artery blockages. Retraction of the sheath allows the self-expanding stent to expand, seating the graft against the aortic wall. Once the endovascular graft is deployed, it provides a conduit for bloodflow and excludes the aneurysm sac from the general circulation, thereby preventing rupture. Endovascular stent-graft repair (EVSG) of DTAA not only represents an exciting method of treating aneurysms but will demand new and challenging skills from the nurses involved in the care and treatment of patients undergoing this procedure. This type of repair also provides an opportunity for nurses to work collaboratively with physicians to provide optimum care and patient education. This article describes and compares the conventional and endovascular repair of DTAA. It further describes the unique complications that can occur with the endovascular procedure and discusses the nursing implications for both the general and advanced practice nurse in the perioperative arena as well as in long-term follow-up.
INCIDENCE The estimated annual incidence of thoracic aortic aneurysm is 6 cases per 100,000 people; of those cases, only 40% will be located in the descending thoracic aorta.5 Although the incidence is low, the number of people diagnosed with DTAA is thought to be increasing. Factors believed to contribute to this possible rise include increased longevity of the population and improved diagnostic capability.3 There is also a familial incidence of aortic aneurysm. The risk of abdominal aortic aneurysms among first-degree relatives of aneurysm patients is 6 times that of the general population.
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Other less common causes of DTAA include trauma, infection, inflammation, and connective tissue disorder. DTAA also can be congenital or occur as a result of an aortic dissection.13
SIGNS AND SYMPTOMS The majority of thoracic aneurysms are asymptomatic and are discovered incidentally while other health problems are being investigated; only 20% cause symptoms.1-3 Some symptoms are produced as a result of the aneurysm pressing on adjacent structures, resulting in dysphagia, shortness of breath due to compression on the trachea, hoarseness due to left laryngeal nerve compression, or hemoptysis if the aneurysm erodes into the bronchus.8,14 Back pain can occur if the aneurysm erodes into a vertebral body. Chest pain can occur from aneurysmal expansion with resultant pressure or stretching.7 Rarely, patients present with signs of distal embolization of the lower extremities from a thrombus-filled thoracic aneurysm. Some patients present with a ruptured thoracic aneurysm, which is characterized by sudden onset of severe back or chest pain, hypotension, and cardiovascular collapse.8 The physical examination for thoracic aneurysm is usually nondiagnostic. Occasionally, a pulsatile mass can be palpated in the epigastric or supraclavicular region. Rarely, a left supraclavicular or paravertebral bruit can be heard, but diagnosis of thoracic aneurysm must be confirmed with radiologic studies.1 Even though thoracic aneurysm may sometimes cause widening of the mediastinum, which is demonstrated on chest x-ray, this is often misread as simple tortuosity of the aorta and is nondiagnositc.4 One should have a high level of suspicion when evaluating patients with multiple risk factors for aneurysm, such as smoking, hypertension, hyperlipidemia, and first-degree relatives with an aortic aneurysm. Not only is aneurysm formation familial, it is a systemic disease.8 Patients can also present with more than 1 aneurysm. Figure 1. Descending thoracic aortic aneurysm.
CONVENTIONAL LEFT THORACOTOMY REPAIR OF DTAA
Concomitantly, 25% to 30% of people with abdominal aortic aneurysms will develop thoracic aneurysms.8
For the past 40 years, patients have undergone conventional repair of DTAA, and it remains the gold standard. Unfortunately, the procedure involves prolonged general anesthesia with placement of a specialized bifurcated endotracheal tube and transesophageal probe to monitor cardiac activity throughout the procedure. Multiple intravenous lines are placed into various large vessels for continuous monitoring throughout the procedure. Typically, a Swan-Ganz catheter is inserted by the anesthesiologist. Also, a radial arterial line and 1 or 2 peripheral large-bore catheters are placed for rapid infusion of blood and intravenous fluids. In our institution, a spinal catheter is placed in the subarachnoid space at the L4-5 intervertebral level and advanced up to the T12-L1 level. This catheter will remain in place for 48 to 72 hours postoperatively as an adjunct in reducing spinal cord ischemia. Cerebrospinal fluid (CSF) drainage is thought to promote spinal cord artery bloodflow by decreasing the CSF pressure that accompanies reperfusion. Anesthesia preparation time for this procedure is 1 to 2 hours.15 Once the patient is intubated and the invasive lines have been placed, a left thoracotomy is performed, the left lung is deflated for exposure, and the aorta is cross-clamped while the graft is
ETIOLOGIC FACTORS Historically, more than 80% of all thoracic aneurysms were attributed to syphilis; however, with the advent of antibiotics, this infectious disease now comprises fewer than 5% of patients with thoracic aneurysms.8 Atherosclerosis, a degenerative disease of the arterial system, accounts for 80% of the aneurysms found in the thoracic aorta.8 Patients with aneurysmal dilation have an elevation of elastolytic enzymes that cause fragmentation of the supporting elements of the aortic wall. The degenerative structural change within the muscular, elastic, and collagen fibers of the aortic wall produces a weakness in the wall of the aorta that leads to progressive dilation and subsequent aneurysm formation.9 Known factors that will contribute to aneurysm growth are uncontrolled hypertension by virtue of the increased pressure in the aneurysm sac and the continued use of tobacco.10 The by-products of smoking promote the breakdown of the collagen matrix, which is one of the supporting structures of the aortic wall.11,12
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Figure 2. A, DTAA and EVSG before graft deployment. B, DTAA and EVSG after graft deployment.
sewn in place. During this time, the bloodflow to the visceral vessels (celiac, superior, and inferior mesenteric arteries) and the renal arteries is interrupted. There is also interruption of the bloodflow from the intercostal arteries to the spinal cord during cross-clamping of the aorta. Some surgeons may use a shunt or place the patient on bypass during this part of the procedure to provide bloodflow to the viscera and lower extremities. Patients often require blood replacement. The average length of time in the operating room is 6 hours. Complications include prolonged ventilatory support, paraplegia, renal failure, left ventricular failure, ischemic bowel, and coagulopathies.2,3 Mortality rates average 5% to 10%, and morbidities can be as high as 40%.2,13 Patients are hospitalized for 7 to 14 days, barring any complications and are discharged home with family members or with medical assistance, such as a visiting nurse or physical therapist. Occasionally, patients will require a 1- to 2-week stay in a rehabilitation facility to gain strength and endurance. The recuperative period is usually 6 to 12 weeks before patients return to baseline.
ENDOVASCULAR STENT-GRAFT REPAIR OF DTTA Because these devices are still investigational, all of the patients are prepared according to strict Federal Drug Administration protocols. At Mount Sinai Hospital in New York, EVSG repair is done in the operating room with the patient under epidural anesthesia. The patient is positioned supine on a fluoroscopy table. Light sedation is given so that patients can comfortably tolerate lying still for the 1 to 2 hours necessary for
the procedure. Nasal oxygen is given by cannula at 2 to 3 L/minute. A jugular central venous pressure line is inserted as well as a radial arterial line and a peripheral intravenous line. Oxygenation is monitored with pulse oximetry. A Foley catheter is inserted. Peripheral pulses are palpated and marked. The abdomen, pelvis, and groins are prepared. A prophylactic dose of antibiotic is given intravenously. Next, the access vessel, usually the iliac or femoral artery, is exposed via cutdown. The patient is given heparin, and a protective sheath is introduced into the access vessel. The sheath acts as a protective device for the artery providing a conduit through which all instrumentation takes place. A guide wire is introduced into the aorta, followed by the delivery system that houses the endovascular stent-graft. Before the device can be deployed, patients are given a dose of the beta-blocker and a vasodilator to decrease the mean arterial pressure to 50 to 60 mmHg. This results in decreased bloodflow to prevent downward migration of the stent during the critical moment of deployment of the graft. After successful placement of the graft, a completion angiogram is performed to ensure proper positioning of the endoluminal graft and the absence of endoleak (Figure 2 A and B). An endoleak refers to the continued perfusion of the aneurysm sac after placement of the stent-graft.16 There are different types of endoleaks (Table 1). Ideally though, at this point in the procedure, the aneurysm should be excluded from the general circulation and all bloodflow should now go through the graft. Next, heparinization is reversed with protamine, the introducer sheath is removed, and the arteriotomy is closed. The
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TABLE I CLASSIFICATION OF ENDOLEAKS Type Type Type Type
I: Proximal or distal attachment site leak II: Retrograde flow from patent intercostal arteries III: Fabric tears, disintegration of graft IV: Graft porosity
J Endovasc Surg 1998;5(4):305-9.
patient is transferred to the postanesthesia care unit for an overnight stay. The following day, the patient is transferred to a regular surgical floor for continued observation and mobilization. Discharge is usually on the third or fourth postoperative day.
SCREENING FOR ENDOVASCULAR STENTGRAFT REPAIR Candidacy for endovascular repair to DTAA is dependent on patient anatomy.14 One of the primary considerations is a sufficient amount of normal aorta above and below the aneurysm in which to secure the device since the attachment to the aortic wall is by lateral wall pressure from the stent part of the stent-graft. Technically, this area is referred to as the proximal and distal neck, respectively. Most devices require at least a 2-cm area below the left subclavian artery and 2 cm above the celiac artery.3,7 In some cases, if the proximal neck is inadequate, a subclavian transposition can be performed before EVSG to obtain a more usable aortic neck.14 The proximal and distal necks are also vitally important since the prosthetic device must fit securely up against the aorta to form a tight seal once in place to exclude the aneurysm from the general circulation. Thrombus in this region may result in an unstable landing zone, increasing the likelihood of migration of the graft and possible endoleak. The second anatomic consideration is that of the access vessels. An endovascular device must be inserted into the iliac or femoral artery and navigated up into the thoracic aorta. The diameter of the access vessel has to be large enough to accommodate a device that may be as large as a 24 to 27 French catheter or 8 to 9 mm in diameter.17 Tortuous, calcified, stenotic arteries make access difficult and dangerous, increasing the risk of injury to the artery. The following 2 diagnostic tools are used to evaluate patients for EVSG: spiral computed tomography (CT) scan and an angiogram. The spiral CT scan is done with intravenous contrast and 3-mm cuts. Views need to include the chest, abdomen, and pelvis so that the aneurysm and the access vessels can be visualized. The CT scan is used to determine vessel diameter in calculating the diameter of the EVSG. The angiogram is done with a radiopaque marker catheter labeled in 1-cm increments so that the length of the EVSG can be determined with measurements obtained from the angiogram. The angiogram also provides important information regarding the patency of visceral vessels and intercostal arteries. The measurements taken from
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these 2 radiologic studies help to ensure accurate sizing of the endovascular device.17
Advantages There are many advantages to endovascular repair of DTAA (Table 2). The most important advantage is that it provides a treatment modality for many patients who otherwise would not be candidates for conventional repair because of their comorbidities. Other advantages include decreased length of hospital stay, shorter recuperation, and a decrease in mortality and morbidity for a category of high-risk patients.
Complications in EVSG repair and their implications for nursing Endovascular repair has brought about a unique subset of complications inherent to this new technology. Optimal postoperative care cannot be given without the professional nurse knowing the signs and symptoms of these complications and possessing the assessment skills to rapidly evaluate and institute the proper measures to expedite treatment. Endoleak is the most common complication associated with EVSG repair (Figure 3).3,5,17 It refers to the continued perfusion of the aneurysm sac after placement of the graft. This is due to a poor proximal or distal seal, patent intercostal arteries that continue to perfuse the aneurysm, ineffective seal between devices if more than 1 device was used, or device failure. Endoleaks may also occur as a result of upward or downward migration.17 This is thought to occur as the morphology of the aneurysm sac shrinks in response to exclusion by the endoluminal graft.17 Endoleaks can occur in the early postoperative period or later in long-term follow-up, thus careful follow-up of these patients is mandatory.16 As with open repair, paraplegia can occur.17 Even though the endovascular approach avoids spinal cord ischemia due to crossclamping, there is still a risk of spinal cord injury due to occlusion of intercostal arteries covered by the endograft. Time is of the essence because the duration of cord ischemia is the most important factor in the onset of paraplegia.18 Placement of CSF drainage postoperatively, if implemented early, has been shown in selected cases to alleviate this problem by allowing for improved collateral circulation to the spinal cord.18,19 Embolic stroke is a complication that can occur as a result of the passage of guide wires and instruments at the level of the aortic arch. Embolization can also occur into visceral and renal arteries, resulting in ischemic bowel or kidney. Microemboli can also travel downstream, resulting in ischemic changes of the lower extremities. Postimplantation syndrome is occasionally seen and typically begins within 24 hours of stent-graft placement. This syndrome consists of a spontaneously resolving fever, leukocytosis, and occasionally, transient thrombocytopenia. Although the exact etiologic factor is unknown, the symptoms are thought to be related to activation of cytokines that results from thrombosis in the excluded aneurysm with the release of coagulation proteins and platelets.20 Usually, these symptoms can be managed with mild analgesics or anti-inflammatory agents such as acetaminophen or ibuprofen. The symptoms usually subside within 1 week.
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TABLE II COMPARISON OF CONVENTIONAL REPAIR VERSUS ENDOVASCULAR REPAIR OF DATA EVSG repair Surgical procedure Anesthesia Limitations Blood loss Paraplegia Hospital stay Recuperation Follow-up Long-term durability Mortality
Groin incision Epidural/spinal Anatomy Minimal 3% 3-4 days 7-10 days Every 3-6 months for 1 year, then annually Unknown 10%
Conventional Thoracotomy General Comorbidities 6-8 units 3%-15% 7-14 days 6-12 weeks Annually Lifetime guarantee 10%
thoracic grafts are rigid and must be navigated through sometimes tortuous, calcified, stenotic iliac and femoral arteries and have the potential for injury. Other insertion site complications include hematoma, lymphocele, pseudoaneurysm, and wound infection.17
NURSING IMPLICATIONS Nurses play a key role in the management of EVSG patients. They are often the first person contacted or the first person available to assess and evaluate patients both before surgery and postoperatively. Therefore, nurses need to be knowledgeable about the procedure itself and the complications that can ensue. Accurate assessment is vital.
Preoperative nursing implications Figure 3. CT scan of chest with endoleak. Arrow, Endoleak contrast in aneurysm sac.
It is quite common for patients to develop a pleural effusion after EVSG repair of the thoracic aneurysm. An inflammatory reaction of the aortic wall occurs as a result of the pressure of the stent-graft on the aorta and the thrombosis of blood in the excluded aneurysm sac. Occasionally, the effusion can become quite significant and cause shortness of breath, requiring thoracentesis to relieve the symptom. The effusion may recur over a few weeks and may require repeated drainage.21 Some patients may report the sudden onset of chest and back pain a few days after EVSG repair. Obviously, myocardial infarction or device failure with rupture of the aneurysm must be ruled out, but a frequent cause is delayed thrombosis of the intercostal arteries and resultant pain from ischemia of the paraspinal muscles. The continued flow into the aneurysm sac can cause pain from the inflammatory response of the paraspinal muscles. In some patients, this may persist for 1 week or more. Lastly, local complications can occur as a result of injury to the access vessel. These include laceration, rupture, or thrombosis of the femoral or iliac artery. The large delivery systems for
Patients usually come to the office of the vascular surgeon in a panic after having been told they have a thoracic aneurysm. First and foremost, establish rapport with patients by listening intently and offering reassurance. Put patients at ease by focusing on early diagnosis and safe repair before rupture. Next, obtain a thorough history. Note any complaints that might indicate the thoracic aneurysm is symptomatic such as unexplained chest or back pain, dysphagia, shortness of breath, hoarseness, or signs of distal embolization. A thorough arterial assessment with specific attention to the abdomen and both popliteal fossa should be performed to detect evidence of aneurysm formation elsewhere. Also, a medical evaluation is necessary to identify other risk factors that might affect perioperative morbidity. Once eligibility for EVSG repair is determined, informed consent must be obtained by the physician or a designated person from the research team. Informed consent requires that the patient have a full understanding of that to which he or she has consented. This means that patients need to be informed of all options, including observation; left thoracotomy; open repair, if the patient is a surgical candidate; and endovascular repair. Pictures and diagrams are extremely helpful in explaining the
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procedures and should be available. Patients should understand that EVSG repair is currently considered investigational and that the Federal Drug Administration requires long-term follow-up. Next, to prepare the patient and his or her family for the anticipated surgery, the nurse should review preoperative testing, the operative procedure, and the anticipitated postoperative course for the institution. This information will allow patients and families to plan accordingly for hospitalization and recuperation. Once it is determined that the patient will undergo the procedure, laboratory studies (eg, complete blood count, prothrombin time, partial thromboplastin time, and platelet count and electrolyte, blood urea nitrogen, creatinine, and glucose levels) are obtained. A chest radiograph, electrocardiogram, cardiac evaluation with stress test, CT scan of the chest abdomen and pelvis, and an angiogram with marker catheter are also necessary. One must be aware of and proceed with caution with patients who have renal insufficiency. The patient should be well hydrated, and acetylcysteine or fenoldopam is frequently used as a renal protective agent.22,23 For patients allergic to contrast, steroids and diphenhydramine (Benadryl) are given before the procedure.
Postoperative nursing implications Nurses caring for EVSG patients should be knowledgeable about the EVSG procedure and the possible complications that could ensue. Subtle changes in physiologic parameters can lead to disasters if not acted upon immediately. The patient’s appearance can be quite misleading since patients are insensate from the waist down because of epidural anesthesia. Upon admission to the postanesthesia care unit (PACU), blood pressure measurements need to be taken in both arms. A graft placed too high in the aorta, partially or totally occluding the left subclavian artery, would produce a low or absent blood pressure reading in the left arm. Document the presence or absence of pulses in both the upper and lower extremities as well as any pressure differences, and inform the surgeon promptly if any symptoms occur because further intervention may need to be taken immediately. The access site for the introduction of the graft is usually the iliac or femoral artery, so the insertion site should be assessed for the presence of pulsation, bleeding, or hematoma formation. Also, note distal pulses and skin changes of the lower extremities, posterior thorax, lumbar area, or buttocks that might indicate signs of embolization, such as irregular-shaped, cyanotic areas that are exquisitely tender. Neurologic evaluations are of utmost importance. Embolic stroke and paraplegia are known complications. Embolic stroke can cause a change in vital signs, such as visual changes, aphasia, alteration in the level of consciousness, changes in mentation, or sensory or motor loss in the extremities.24 Most institutions have standardized neurologic assessment forms that should be used throughout the patient’s hospital stay. Close observation and accurate documentation help to determine the area of the brain or the level of the spinal cord that is affected. Paraplegia can occur secondary to spinal cord ischemia. The ischemic changes that occur can result in mild paresis or paralysis of the extremities. Patients have had epidural anesthetics and
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are insensate in the immediate postoperative period; therefore, observation and frequent neurologic examinations are critical. The nurse should note the return of lower extremity sensation and motor ability with the appropriate muscle strength. If any sign of paresis or paralysis develops, the physician should be notified immediately because spinal drainage may be implemented and in some cases can completely reverse this complication. Embolization can occur to visceral vessels as well as renal arteries; therefore, the abdominal examination is an essential part of the assessment. Signs and symptoms of acute mesenteric ischemia are usually sudden and dramatic. Acute abdominal pain is accompanied by vomiting or bowel movement or both. Patients complain of intense pain, but the abdomen is usually soft and minimally tender to palpation.25 These symptoms require urgent diagnostic testing and intervention. Embolization to the renal artery can also result in severe abdominal or flank pain and can impair renal function. A Foley catheter is routinely inserted at the onset of the procedure and remains for 24 hours postoperatively to measure urinary output. Blood urea nitrogen and creatinine levels are also monitored frequently because patients receive a significant volume of contrast intraoperatively to ensure proper placement of the EVSG. The patient’s temperature should be monitored every 4 hours, and any signs and symptoms of a post-implantation syndrome should be noted. Fever that persists after 14 days warrants further investigation to eliminate any possible source of infection. Lastly, patients who develop back or chest pain after the procedure should be re-evaluated by the cardiology department. Once it is determined that the source of the discomfort is not cardiac in origin, CT scan of the chest is obtained to look for an endoleak. If no endoleak is found, the patient can be safely monitored by following-up on the character and severity of the pain. The pain should not increase, and the character should not change, other than to improve. At Mount Sinai Hospital, all endovascular patients receive standardized, home-going instructions that detail activity, wound care, diet, medications, continued medical care, and instructions for follow-up appointment. Also listed are warnings and precautions for symptoms that may warrant immediate medical attention and the 24-hour telephone number where a member of the endovascular team can be reached. The patient’s primary care nurse reviews the instructions with the patient at the time of discharge.
Long-term surveillance One of the salient factors in determining whether a patient should have an EVSG is the unknown long-term durability of the graft itself and its ability to maintain proper position over time since the structure of the native aorta is subject to change. The aneurysm sac can shrink in response to exclusion by the EVSG or in isolated cases can continue to increase. These changes can distort the proximal and distal landing zones and predispose the patient to endoleak. Therefore, patients with EVSG repair will require lifetime follow-up. Those providing long-term follow-up
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TABLE III WARNINGS/PRECAUTIONS Please notify our office immediately if you experience any of the following: 1. Fever more than 101° F or 39° C 2. Redness, increased swelling, drainage, or bleeding from groin incisions 3. Severe or unusual chest, back, or abdominal pain 4. Severe or unusual arm or leg pain or weakness 5. Numbness and tingling of arm or leg 6. Unusual shortness of breath or difficulty with breathing 7. Dizziness, sudden weakness
and telephone triage must be constantly aware of both the subtle and obvious symptoms that may signal a problem. After discharge from the hospital, patients are scheduled for an office visit in 7 to 10 days. The postoperative spiral CT scan with intravenous contrast and 3-mm cuts is done at this time rather than in the hospital because dye can be retained in the aneurysm sac from the original procedure and give a false impression of endoleak. A 4-view chest x-ray is obtained (ie, anteroposterior, lateral, right, and left oblique views). The chest x-ray is reviewed for fracture of the struts of the EVSG, pleural effusion, and graft migration. During the postoperative office visit, the patient is carefully examined and vital sign measurements, bilateral arm blood pressure readings, and palpation of brachial and radial pulses are documented. Heart and lung fields are auscultated. Abdominal examination is performed, and the groin wound is inspected. Lower extremities are evaluated for signs of embolization; the presence or absence of distal pulses is also noted. Barring any abnormalities, the patient will return for postoperative checkups every 6 months. If an endoleak is discovered and the size of the aneurysm sac remains stable or decreases as measured on CT scan, no intervention is needed. If, however, an endoleak is discovered and the aneurysm sac increases more than 5 mm, the endoleak is identified via angiogram and the vessel perfusing the sac is coiled to prevent further flow. If the endoleak is due to graft migration, an insufficient proximal or distal seal, or a leak between the pieces of the EVSG, another piece of EVSG can sometimes be telescoped into place. Patients are followed-up every 6 months. Late complications do occur, and it is vital for the nurse to review the warning signs and symptoms that prompt immediate investigation at each patient visit (Table 3). Patients are strongly urged to keep the home-going instruction sheet as a handy reference. It lists a 24-hour telephone number in case of emergency. Because our general knowledge and experience with thoracic grafts are still growing, all patient complaints are treated seriously. Any new onset of back, chest, or leg pain or any extremity pain, weakness, numbness, tingling, or change in temperature warrants immediate investigation.
SEPTEMBER 2002
FUTURE IMPLICATIONS The future of endoluminal repair of thoracic aneurysms is extremely exciting. Nurses caring for patients with endovascular repair of DTAA have the opportunity to be on the cutting edge of rapidly advancing technology. This minimally invasive surgery has the potential to be performed with increasing frequency because of more training programs for physicians, increased availability of devices, improvement in devices and delivery systems, and patient demand. The indications are expanding, and use now includes selected cases of trauma, penetrating ulceration of the aorta, acute dissection, and aortocaval fistula.26-28 The thoracic devices are also used in combination with standard surgical procedures, such as an open repair of abdominal aortic aneurysm followed by EVSG repair of a coexisting thoracic aneurysm. Nurses need to respond and embrace this innovative approach to repairing thoracic aneurysms for patients who previously had no alternative to conventional repair. As technology improves and the patients’ involvement in making their own health care decisions increases, so will the demand for endovascular repair. The advanced practice nurse needs to educate patients, nurses, and other health care providers. To do this, one must keep abreast of the changes in technology. Most importantly, nursing must develop a body of knowledge relative to the physical and emotional responses to this procedure to better provide optimal, holistic nursing care. Last but not least, as health care providers, the risk factors for atherosclerotic disease and aneurysm must be addressed. Patients at high risk for developing aortic aneurysm must be identified and viewed with a high level of suspicion. Hypertension and smoking cessation must be urged more aggressively. Guidelines for screening high-risk patients need to be developed and implemented.
REFERENCES 1. Bickerstaff LK, Pairolero PC, Hollier LH. Thoracic aortic aneurysms: a population based study. Surgery 1982; 92:1103-8. 2. Crawford ES, DeNate RW. Thoracoabdominal aortic aneurysm: observations regarding natural course of disease. J Vasc Surg 1986;3:578-82. 3. Temudom T, D’Ayala M, Marin ML, Hollier LH, Parsons R, Teodorescu V, et al. Endovascular grafts in the treatment of thoracic aortic aneurysms and pseudoaneurysms. Ann Vasc Surg 2000;14:230-8. 4. Hollier LH, Hamilton IH. Thoracoabdominal aortic aneurysms In: Moore WS, editor. Vascular surgery: a comprehensive review. Philadelphia: WB Saunders; 1998. p. 41733. 5. Mitchell RC, Miller DC, Dake MD. Stent-graft repair of thoracic aneurysms. Semin Vasc Surg 1997;10:257-71. 6. Greenberg R, Risher W. Clinical decision making and operative approaches to thoracic aortic aneurysms. Surg Clinics North Am 1998;78:805-25. 7. Ehrlich M, Grabenwalger M, Cartes-Zumelzu F. Endovascular stent graft repair for aneurysms of the descending thoracic aorta. Ann Thorac Surg 1998;66:19-25.
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8. Fann JI, Miller DC. Descending thoracic aortic aneurysm. In: Baul AE, Gena AS, Hammond GL, Laks H, Nauaheim KS, editors. Glenn’s thoracic and cardiovascular surgery. Stanford: Appleton & Lange; 1995. p. 2255-72. 9. Fann JI, Miller DC. Endovascular treatment of descending thoracic aortic aneurysms and dissections. Surg Clinics North Am 1999;79:551-73. 10. McKinsey JF, Graham A, Gerwertz S. Diseases of the vascular system. In: Lawrence P, editor. Essentials of general surgery. Philadelphia: Lippincott, Williams & Wilkins; 2000. p. 435-59. 11. D’Ayala M. Grafting for thoracic aortic aneurysms. In: Marin ML, Hollier LH, editors. Advanced treatment for vascular disease. New York: Futura; 2000. p. 95-107. 12. Tilson MD, Hingorini AP, Grogory AK. Pathogenesis of aneurysms. In: Greenfield LJ, Mulholland MW, Oldham KT, Zelenock GB, Lillimore KD, editors. Essentials of surgery: scientific principles of practice. Philadelphia: LippincottRaven; 1997. 13. Rehm JP, Grange JJ, Baxter BT. The formation of aneurysms. In: Rutherford RB, editor. Seminars in vascular surgery. Philadelphia: WB Saunders; 1997. p. 193-202. 14. Fann JL, Slonim SM, Miller DC. Endovascular treatment of thoracic aortic aneurysms and dissections. In: Calligaro KD, Dougherty MJ, Hollier LH, editors. Diagnosis and treatment of aortic and peripheral arterial aneurysms. Philadelphia: WB Saunders; 1999. p. 97-112. 15. Gravereaux EC, Faries PL, Burks JA, Latessa VR, Spielvogel D, Hollier LH, et al. Risk of spinal cord ischemia after endograft of thoracic aortic aneurysms. J Vasc Surg 2001; 34:997-1003. 16. Dietch JS, Yano OJ. Description and classification of endoleaks. In: Marin ML, Hollier LH, editors. Endovascular grafting: advanced treatment for vascular disease. Armonk (NY): Futura; 2000. p. 133-45. 17. Fann JL, Dake MD, Mitchell RS, Semba CP, Miller DC. Endovascular management of descending thoracic aortic aneurysms. In: Parodi JC, Veith FJ, Marin ML, editors. Endo-
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vascular grafting techniques. Baltimore: Lippincott, Williams & Wilkins; 1998. p. 2255-71. 18. Tiesenhausen K, Amann W, Koch G, Hausegger KA, Oberwalder P, Rigler B. Cerebrospinal fluid drainage to reverse paraplegia after endovascular thoracic aortic aneurysm repair. J Endovasc Therapy 2000;7:132-5. 19. Bethel SA. Use of lumbar cerebrebrospinal fluid drainage in thoracoabdominal aneurysm repairs. J Vasc Nurs 1999;17: 53-8. 20. Jenson C. Stent grafts. In: Eton D, editor. Vascular disease: a multispecialty approach to diagnosis and management. Georgetown (TX): Landes Bioscience; 1999. p. 252-83. 21. Martin GH, O’Hara PJ, Hertzer NR, Mascha EJ. Surgical repair of aneurysms involving the suprarenal, visceral and lower thoracic aortic segments: early results, late outcomes. J Vasc Surg 2000;31:851-61. 22. Safirstein R, Andrade L, Vieria JM. Acetylcysteine and nephrotoxic effects of radiographic contrast agents—a new use for an old drug. N Engl J Med 2000;343:210-2. 23. Singer IE. Potential of dopamine A-1 agonists in the management of acute renal failure. Am J Kidney Dis 1998;31: 743-55. 24. Bradley M, Pearce WH. Extracranial vascular disease. In: Fahey V, editor. Vascular nursing. Philadelphia: WB Saunders; 1999. p. 270-90. 25. Abdessalam S, Baxter BT. Mesenteric ischemia. In: Fahey V, editor. Vascular nursing. Philadelphia: WB Saunders; 1999. p. 330-9. 26. Lobato AC, Quick RC, Philips B, Vranic M, Lopez JR, Douglas M. Immediate endovascular repair for descending thoracic aortic transection due to blunt trauma. J Endovasc Therapy 2000;7:16-20. 27. Umsheid T, Stelter WJ. Endovascular treatment of an aortic aneurysm rupture into the inferior vena cava. J Endovasc Surg 2000;7:31-5. 28. Biasi GM. Aortocaval fistula: a challenge for endovascular management. J Endovasc Surg 1999;6:378.
WRITING AWARD The Journal of Vascular Nursing Article Award honors nurse authors for their efforts to create a publishable manuscript. Manuscripts will be judged for accuracy of content, relevance to vascular nursing practice, and excellence of writing style. All feature articles published in the Journal of Vascular Nursing during the calendar year will be considered for the JVN Article Award. The award recipient will be given a plaque commemorating the award and a cash prize donated by Mosby. The award and cash prize will be presented at the annual symposium. Announcement of the award recipient will appear in the Journal of Vascular Nursing and in SVN...prn.
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SEPTEMBER 2002
Stent graft repair Contact Hours: 1.0 Test ID: JVN0291
Minimum Passing Score: 70% Test Processing Fee: $10.00
OBJECTIVES:
1. Describe the incidence and etiology of DTAA. 2. Identify repair of DTAA. 3. Discuss nursing implications in caring for DTAA patients. 1. What is the risk of abdominal aortic aneurysms (AAA) to primary relatives of aneurysm patients? a. Twice as great b. Four times as great c. Six times as great d. Ten times as great
6. What is the most common complication of endovascular stent graft repair? a. Endoleak b. Paraplegia c. Stroke d. Pleural effusion
2. Of those patients with AAA, what percentage will develop thoracic aneurysms? a. 10%–15% b. 25%-30% c. 45%-50% d. 60%– 65%
7. If the graft were to occlude the subclavian artery, what would be observed? a. Bounding pulses b. Low or absent BP in left arm c. Hypertension d. Weak hand grips
3. Which is the most common cause of thoracic aneurysms? a. Atherosclerosis b. Congenital c. Infection d. Trauma 4. What percentage of thoracic aneurysms are symptomatic? a. 10% b. 20% c. 30% d. 40% 5. A risk factor not associated with possible aneurysm is? a. Smoking b. Hypertension c. Hyperlipidemia d. Diabetes
8. Reversing complications of paraplegia postoperatively can be done with: a. Additional surgery b. Corticosteroid therapy c. Spinal drainage d. Repositioning of the stent 9. Acute abdominal pain with vomiting or bowel movement may be indicative of: a. Embolization b. Poor analgesia control c. Infection d. Stent misplacement 10. Fabric tears and disintegration of the graft is considered a Type __ endoleak. a. I b. II c. III d. IV
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Nursing Continuing Education Answer/Enrollment Form JOURNAL OF VASCULAR NURSING Test ID#: JVN0291 Minimum Passing Score: 70%
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