Vascular Surgery

James I. Fann MD¹

R. Scott Mitchell MD¹

Clayton Kaiser MD¹

Stephen T. Kee MD (Endovascular stent-grafting)¹

Michael D. Dake MD (Endovascular stent-grafting)¹

Pieter J. A. van der Starre MD, PhD²

¹SURGEONS

²ANESTHESIOLOGIST

CAROTID ENDARTERECTOMY (VASCULAR)

SURGICAL CONSIDERATIONS

Description: Carotid endarterectomy (CEA) continues to be one of the commonly performed open vascular surgery procedures in the United States, even as carotid stenting is being employed as an alternative approach. Because of presumed microemboli from stenotic/ulcerated plaques at the carotid bifurcation, CEA is an effective procedure to reduce the risk of subsequent stroke. The NASCET Collaborators determined, in a prospective, randomized, blinded trial, that CEA is more effective than medical therapy for symptomatic patients with internal carotid artery narrowing between 60% and 90%. Symptoms are usually hemispheric (contralateral, upper or lower extremity paresis or numbness) or retinal (unilateral monocular blindness). Symptoms may be transient (TIA or reversible ischemic neurological deficit [RIND]) or permanent (CVA). The Asymptomatic Carotid Atherosclerosis Study (ACAS) has shown benefit from prophylactic CEA in asymptomatic patients with > 60% stenosis of the internal carotid artery. The Asymptomatic Carotid Surgery Trial 1(ACST-1) is a recent randomized study of patients assigned to immediate CEA or deferral of any carotid artery procedure. Recruiting patients between 1993 to 2003 and following until 2006-08, this study shows that successful CEA for asymptomatic patients younger than 75 years of age reduces 10-year stroke risks, particularly for disabling or fatal strokes. Further studies will provide information on the risks from unoperated carotid lesions (or optimal medical management), on future stroke risks, and on 10-year survival rates.

Although some surgeons routinely prefer local anesthesia, most prefer GA with careful hemodynamic monitoring because of the frequent concomitant CAD. The carotid artery is approached through an oblique neck incision along the anterior border of the sternocleidomastoid muscle. After division of the common facial vein, the carotid sheath is opened and the carotid artery is exposed, avoiding injury to the phrenic, vagus, ansa hypoglossi, and hypoglossal nerves (Fig. 6.3-1). After controlling the internal, external, and common carotid arteries, heparin is administered, and the internal, external, and common carotid arteries are clamped sequentially. To maintain carotid perfusion, an indwelling shunt may be utilized (Fig. 6.3-2B), at the discretion of the surgeon. During clamping mean arterial blood pressure is maintained at approximately 100 mm Hg with phenylephrine infusion or boluses. An endarterectomy plane is established proximally (Fig. 6.3-2C) and developed distally into both the external and internal branches, with establishment of a fine tapered end point. After removal of all thrombus, loose smooth-muscle fibers and endothelium, the arteriotomy is closed, with or without a patch, the artery flushed, and flow restored. The incision is closed after meticulous hemostasis has been ensured.

Usual preop diagnosis: Carotid artery disease

▪ SUMMARY OF PROCEDURE

Position	Supine with neck extended and turned away from the side of the lesion
Incision	Anterior to sternocleidomastoid from earlobe to base of neck or curvilinear in a skin crease over the carotid bifurcation
Special instrumentation	EEG monitor; ± shunt
Unique considerations	Capability to measure stump pressure may be needed. This can be accomplished by a high-pressure arterial line passed off the field to a pressure transducer. Avoid ↓ BP during carotid cross-clamping. An indwelling shunt may be utilized to restore carotid perfusion. Heparin 5000-10,000 U 5 min prior to cross-clamping, and protamine may be given after restoration of flow.
Antibiotics	Cefazolin 1 g iv at induction of anesthesia
Surgical time	Carotid cross-clamp: 30 min Total operating time: 90 min
Closing considerations	To assess the patient’s neurologic status, it is best to be able to awaken and extubate the patient at the conclusion of the procedure. Avoidance of HTN is also critical during this period because the endarterectomy tissues are thin and friable.
EBL	100-200 mL
Postop care	ICU × 12-24 h; BP control; cardiac monitoring
Mortality	1%
Morbidity	MI: Major cause of postop mortality Cranial nerve injury (recurrent and superior laryngeal nerves): 39% Restenosis Asymptomatic: 9-12% Symptomatic: < 3% Neurologic complications: < 2% Hemorrhage: 1% False aneurysm: < 0.5%
Pain score	3-5

Figure 6.3-1. Exposure of the carotid bifurcation. (Reproduced with permission from Scott-Conner CEH, Dawson DL: Operative Anatomy, 2nd edition. Lippincott Williams & Wilkins, Philadelphia: 2003.)

Figure 6.3-2. Carotid endarterectomy: A. Following occlusion of the superior thyroid and internal, external, and common carotid arteries, an arteriotomy is performed opposite the external carotid take off. B. A shunt may be placed to restore internal carotid flow. C. Plaque is separated from the artery wall. (Reproduced with permission from Scott-Conner CEH, Dawson DL: Operative Anatomy, 2nd edition. Lippincott Williams & Wilkins, Philadelphia: 2003.)

ANESTHETIC CONSIDERATIONS

See Anesthetic Considerations for Carotid Endarterectomy (Neurosurgical) in Extracranial Procedures, p. 135.

Suggested Readings

1. Doig D, Brown M: Carotid stenting versus endarterectomy. Annu Rev Med 2012; 63:259-76.

2. Flanigan DP, Flanigan ME, Dorne AL, et al: Long-term results of 442 consecutive, standardized carotid endarterectomy procedures in standard-risk and high-risk patients. J Vasc Surg 2007; 46:876-82.

3. Halliday A, Harrison M, Hayter E, et al: Asymptomatic Carotid Surgery Trial (ACST) Collaborative Group. 10-year stroke prevention after successful carotid endarterectomy for asymptomatic stenosis (ACST-1): a multicentre randomized trial. Lancet 2010; 376:1074-84.

4. Hines GL, Feuerman M, Cappello D, et al: Results of carotid endarterectomy with pericardial patch angioplasty: rate and predictors of restenosis. Ann Vasc Surg 2007; 21:767-71.

5. Howell SJ: Carotid endarterectomy. Br J Anaesth 2007; 99:119-31.

6. Mantese VA, Timaran CH, Chiu D, Begg RJ, Brott TG, CREST Investigators: Carotid Revascularization Endarterectomy versus stenting Trial (CREST): stenting versus carotid endarterectomy for carotid disease. Stroke 2010; 41:S31-4.

7. Moritz S, Kasprzak P, Arlt M, et al: Accuracy of cerebral monitoring in detecting cerebral ischemia during carotid endarterectomy: a comparison of transcranial Doppler sonography, near-infrared spectroscopy, stump pressure, and somatosensory evoked potentials. Anesthesiology 2007; 107:563-9.

8. NASCET Collaborators: N Engl J Med 1991; 325:445-53.

9. Raman G, Moorthy D, Hadar N, et al: Management strategies for asymptomatic carotid stenosis: a systematic review and meta-analysis. Ann Intern Med 2013; 158:676-85.

10. Rockman C, Loh S: Carotid endarterectomy: still the standard of care for carotid bifurcation disease. Semin Vasc Surg 2011; 24:10-20.

11. Stoneham MD, Thompson MP: Arterial pressure management and carotid endarterectomy. Br J Anesth 2009; 102: 442-52.

12. Young B, Moore WS, Robertson JT, et al: An analysis of perioperative surgical mortality and morbidity in the Asymptomatic Carotid Atherosclerosis Study. ACAS Investigators. Stroke 1996; 27:2216-24.

REPAIR OF THORACIC AORTIC ANEURYSMS

SURGICAL CONSIDERATIONS

Description: Repairs of aneurysms of the ascending, transverse arch, and descending thoracic aorta are performed to repair expanding or leaking aneurysms, or prophylactically to prevent rupture. Patients with Sx of rapid expansion or aneurysm leaking may require urgent repair. Each surgical type—ascending, arch, and descending—is considered separately, as follows. Aneurysms of the ascending aorta may arise 2° the degenerative changes of atherosclerosis (exacerbated by old age, HTN, tobacco use); from inborn errors of metabolism (Marfan syndrome); or from poststenotic dilatation and continued expansion of a chronic dissection. Diseases of the entire ascending aorta, including the sinuses of Valsalva, as in Marfan syndrome and annuloaortic ectasia, require replacement of the ascending aorta and aortic root with a composite valved conduit or a valve-sparing aortic root replacement (VSARR), whereas acquired diseases limited to the ascending aorta usually allow replacement of the aorta distal to the sinotubular ridge. Repair of the ascending aorta is usually accomplished on full CPB with an aortic cross-clamp placed just proximal to the innominate artery and arterial inflow through the femoral artery. The aneurysmal ascending aorta is replaced with a Dacron tube graft from the sinotubular ridge to the innominate artery. Dilatation of the sinuses of Valsalva mandates replacement with a composite valved conduit sewn proximally to the aortic annulus and distally to a normal caliber ascending aorta, with coronary ostia reimplanted in the side of the tube graft, although in some cases with a normal-appearing aortic valve VSARR may be performed.

Aneurysms of the aortic arch are the least common of thoracic aortic aneurysms. Because of the need for concomitant replacement of the arch vessels, however, they are the most complex to repair. Total CPB is utilized, and cerebral protection is accomplished either by CPB perfusion of one or all cerebral vessels, by retrograde cerebral perfusion (RCP), or by profound hypothermic circulatory arrest at 15-18°C. Repair can originate from the aortic annulus and extend distally to the mid-descending thoracic aorta at the level of the carina. Routine caval cannulation is accomplished via a median sternotomy, and arterial access is gained via the femoral artery or axillary artery. If circulatory arrest is to be used, the patient is cooled to 15-18°C, the heart is arrested, and with no distal cross-clamp, distal anastomosis is accomplished, followed by implantation of the cerebral vessels attached to an island of aorta. This procedure is often performed with the use of RCP to remove all air from the cerebral circulation. Perfusion is then reinstituted, the graft clamped proximal to the innominate artery, and the proximal anastomosis performed, while the patient is being rewarmed. Alternatively, if one elects to perfuse the cerebral vessels, the innominate and left carotid arteries can be individually cannulated and perfused via a “Y” connection from the femoral arterial perfusion line. If axillary cannulation is used alone, antegrade cerebral perfusion can be achieved by control of the proximal innominate artery. This is termed “unilateral cerebral perfusion” and requires close monitoring with cerebral oximetry to estimate the adequacy of contralateral (e.g., left sided) perfusion. If a unilateral drop in cerebral oximetry occurs the surgeon may convert to bilateral perfusion by placing a catheter into the left carotid artery from inside the arch. The necessity for profound hypothermic circulatory arrest is thus avoided. After completion of the distal aortic arch, vessel island, and proximal aortic anastomoses, weaning from CPB and subsequent steps proceed in a routine fashion.

Repair of aneurysms of the descending thoracic aorta is usually performed for symptomatic and leaking aneurysms, enlarging aneurysms, and aneurysms of sufficient size to warrant prophylactic repair. Aneurysm repair is accomplished through a left posterolateral thoracotomy on full or partial CPB. After entry into the left thorax, venous drainage for CPB may be obtained from the left atrium (partial bypass) or the femoral vein (full bypass), and arterial return is via the femoral artery. This is termed “unilateral cerebral perfusion” and requires close monitoring with cerebral oximetry to estimate the adequacy of contralateral (e.g., left-sided) perfusion. If a unilateral drop in cerebral oximetry occurs, the surgeon may convert to bilateral perfusion by placing a catheter into the left carotid artery from inside the arch. If partial bypass without an oxygenator is elected, thus minimizing the amount of heparin necessary, venous access can be gained via the pulmonary veins or left atrium and arterial return via the femoral artery or distal thoracic aorta. After institution of bypass, the aorta is cross-clamped above and below the aneurysm, the aorta is divided, a tube graft is interposed, and clamps are removed. The patient is weaned from bypass, and the operation is terminated in the routine fashion.

Usual preop diagnosis: Enlarging or symptomatic aortic aneurysm

▪ SUMMARY OF PROCEDURES

	Ascending Aorta	Transverse Arch	Descending Aorta
Position	Supine	⇚	Lateral decubitus with left side up
Incision	Median sternotomy	⇚	Left posterolateral thoracotomy with access to femoral artery and vein
Special instrumentation	CPB, if used.	Complete hemodynamic monitors; CPB	⇚ + DLT; lower extremity BP monitor
Unique considerations	Routine CPB hemodynamic monitoring	If profound hypothermic arrest is utilized, neuroprotective adjuncts, including local hypothermia, barbiturates, and steroids, should be used.	OLV; partial CPB
Antibiotics	Cefazolin 2 g iv	⇚	⇚
Surgical time	Aortic cross-clamp: 40-120 min	Aortic cross-clamp: 75-120 min	Aortic cross-clamp: 25-45 min
	CPB: 70-150 min	Circulatory arrest: 30-45 min	CPB: 30-60 min
	Total: 2.5-5 h	CPB: 3-4.5 h Total: 4-6 h	Total: 2.5-4.5 h
Closing considerations	Aggressive management of coagulopathy, if a long pump run is necessary.	Aggressive management of coagulopathy	Replacement of DLT with singlelumen tube
EBL	300-400 mL	400-700 mL	200-300 mL
Postop care	ICU, intubated 5-20 h, depending on preop condition	ICU, intubated 6-24 h	ICU, intubated 5-24 h
Mortality	5-10%	10-15%	⇚
Morbidity	Renal failure: 5-10% CVA: 4-6% Respiratory failure: 3-5% MI: 2-5%	— 2-5% 10% ⇚	10-15% 2-4% 10-15% 2-4%
Pain score	7-10	7-10	9-10

▪ PATIENT POPULATION CHARACTERISTICS

Age range	23-80 yr (mean = 55 yr)	50-75 yr	34-79 yr (mean = 65 yr)
Male:Female	3:1	2:1	2.5:1
Incidence	10-30/yr at tertiary center	5-10/yr at tertiary center	10-30/yr at tertiary center
Etiology	Degenerative disease Atherosclerotic disease	⇚ ⇚ Chronic dissections	⇚ ⇚ ⇚
Associated conditions	CHF (50%); angina (30%); HTN (30%); COPD (15%)	Aortic valve disease (30%); COPD (20%); CAD (15%)	HTN (65%); CAD (50%); COPD (30%); CHF (10%)

ANESTHETIC CONSIDERATIONS

PREOPERATIVE

Typically, patients with thoracic aortic aneurysms have atherosclerosis and HTN. A subset of patients will have a connective tissue disorder (e.g., Marfan syndrome). In contrast with thoracic aortic dissections, thoracic aortic aneurysms may be of a more chronic and asymptomatic nature. A ruptured or leaking aneurysm, however, may have a more precipitous presentation.

Cardiovascular	Arch and ascending aneurysms (60-70% of aneurysms): commonly associated with HTN, cystic medial necrosis, connective tissue disorder (e.g., Marfan syndrome), atherosclerosis, or syphilis. CHF may occur 2° to dilation of the aortic annulus and aortic incompetence (AR). Aneurysmal compression or intrinsic disease of the coronary arteries may result in myocardial ischemia. Descending (30%): usually associated with HTN, cystic medial necrosis, Marfan syndrome, and atherosclerosis. Tests: ECG: [check mark] for LVH, ischemia. ECHO: [check mark] for valvular disease, size and extent of aneurysm, LV function. Angiography: [check mark] exact extent of aneurysm (allows planning of procedure and sites for arterial monitoring), coronary artery anatomy, and degree of occlusion.
Respiratory	Recurrent laryngeal nerve palsy may → hoarseness (ascending/arch aneurysms). Tracheal deviation ± stridor or dyspnea may be present 2° tracheal or bronchial compression ([check mark] CT scan). Hemoptysis or a hemorrhagic pleural effusion suggest an aneurysmal leakage or rupture. The implications include the possibility of compromised oxygenation, risk of massive hemorrhage on thoracotomy, increased intrathoracic pressure, and consequent decreased venous return (especially when IPPV is instituted). Tests: CXR: [check mark] for widened mediastinum, distortion of trachea and left main bronchus (because it may affect the placement of DLT); MRI/CT with contrast: [check mark] anatomic relation of aneurysm to surrounding structures (e.g., trachea/bronchi); others as indicated from H&P.
Neurologic	Any deficit should be well documented as neurologic sequelae (e.g., paraplegia/paraparesia) may occur after surgery.
Renal	Renal problems may occur 2° to AR (↓CO) and heart failure, HTN, or involvement of renal arteries in the aneurysm. Tests: BUN; Cr; consider Cr clearance; electrolytes
Gastrointestinal	Descending aneurysms that involve the celiac or superior mesenteric arteries may → bowel ischemia. Tests: Consider ABG: [check mark] persistent metabolic acidosis (2% bowel ischemia). If indicated by H&P, consider abdominal CT/x-ray: [check mark] ileus.
Hematological	If time permits, consider autologous blood donation; preexisting coagulopathy increases risk of the procedure. Tests: PT; PTT; Hct/Hb
Musculoskeletal	[check mark] Marfanoid appearance; others as indicated from H&P.
Laboratory	Others as indicated from H&P
Premedication	Pain and anxiety may significantly contribute to HTN and should be treated (e.g., morphine 0.1 mg/kg iv ± midazolam 0.025-0.1 mg/kg iv); but avoid obtundation. Because many of these patients present emergently, consider full-stomach precautions—H2 antagonists (e.g., ranitidine 5 0 mg iv), metoclopramide (10 mg iv), and antacids (e.g., Na citrate 0.3 M 30 mL po).

INTRAOPERATIVE

Anesthetic technique: The anesthetic management of patients with aortic dissections and aortic aneurysms are similar in many respects. For intraop and postop management of these conditions, see Anesthetic Considerations for Repair of Acute Aortic Dissections and Dissecting Aneurysms, p. 418.

Suggested Readings

1. Bisschoff MS, Di Luozzo G, Griepp EB, Griepp RB: Spinal cord preservation in thoracoabdominal aneurysm repair. Perspect Vasc Surg Endovasc Ther 2011; 23:214-22.

2. Cheung AT, Pochettino A, McGarvey ML, et al: Strategies to manage paraplegia risk after endovascular stent repair of descending thoracic aortic aneurysms. Ann Thorac Surg 2005; 80:1280-8.

3. Coady MA, Ikonomidis JS, Cheung AT, et al: A surgical management of descending thoracic aortic disease: open and endovascular approaches: a scientific statement from the American Heart Association. Circulation 2010; 121:2780-804.

4. Estrera AL, Sheinbaum R, Miller CC, et al: Cerebrospinal fluid drainage during thoracic aortic repair: safety and current management. Ann Thorac Surg 2009; 88:9-15.

5. Fann JI: Descending thoracic and thoracoabdominal aortic aneurysms. Coron Artery Dis 2002; 13:93-102.

6. Fischbein MP, Miller DC: Long-term durability of open thoracic and thoracoabdominal aneurysm repair. Semin Vasc Surg 2009; 22:74-80.

7. Goodwin MR, Blasius KR, Brand J, Silvay G: One-lung ventilation for surgical repair of thoracic aortic aneurysm. Semin Cardiothorac Vasc Anesth 2013; 17:146-51.

8. Harrer M, Waldenberger FR, Weiss G, et al: Aortic arch surgery using bilateral antegrade selective cerebral perfusion in combination with near-infrared spectroscopy. Eur J Cardiothorac Surg 2010; 38:561-7.

9. Hoel AW: Aneurysmal disease: thoracic aorta. Surg Clin N Am 2013; 93:893-910.

10. Hsu C, Kwan G, van Driel M, Rophael J: Distal aortic perfusion during thoracoabdominal aneurysm repair for prevention of paraplegia. Cochrane Database Syst Rev 2012; Issue 3. Art. No. CD008197.

11. Kahn RA, Stone ME, Moskowitz DM: Anesthetic consideration for descending thoracic aortic aneurysm repair. Semin Cardiothorac Vasc Anesth 2007; 11:205-23.

12. Kazui T, Yamashita K, Washiyama N, et al: Aortic arch replacement using selective cerebral perfusion. Ann Thorac Surg 2007; 83:S796-8.

13. Milewski RK, Pacini D, Moser GW, et al: Retrograde and antegrade cerebral perfusion: results in short elective arch reconstructive times. Ann Thorac Surg 2010; 89:1448-57.

14. Misfield M, Leontyev S, Borger MA, et al: What is the best strategy for brain protection in patients undergoing aortic arch surgery? A single center experience of 636 patients. Ann Thorac Surg 2012; 93:1502-8.

15. Olsson C, Eriksson N, Stahle E, et al: Surgical and long-term mortality in 2634 consecutive patients operated on the proximal thoracic aorta. Eur J Cardiothorac Surg 2007; 31:963-9.

16. Piazza M, Ricotta JJ: Open surgical repair of thoracoabdominal aortic aneurysms. Ann Vasc Surg 2012; 6:600-5.

17. Reilly LM, Chuter TA: Endovascular repair of thoracoabdominal aneurysms: design options, device construct, patient selection and complications. J Cardiovasc Surg 2009; 50:447-60.

18. Stone DH, Brewster DC, Kwolek CJ, et al: Stent-graft versus open-surgical repair of the thoracic aorta: mid-term results. J Vasc Surg 2006; 44:1188-97.

ENDOVASCULAR STENT-GRAFTING OF AORTIC ANEURYSMS

SURGICAL CONSIDERATIONS

Description: The standard treatment for descending thoracic aortic aneurysm is surgical resection of the aneurysm and replacement with a segment of prosthetic graft material. Although resection of aneurysms often can be performed without the need for extracorporeal circulation, the procedure has a reported mortality rate of up to 50% in emergency cases and 12-15% in elective cases. Transluminal endovascular stent-grafting offers an alternative treatment that is less invasive, less hazardous, and potentially less expensive than standard operative repair.

In the initial workup, all patients have contrast-enhanced spiral CT scans of the thorax and thoracic aortography to assess the dimensions of the aneurysms. The most important features to consider in evaluating an aortic aneurysm for endovascular stent-graft treatment is the presence of an adequate proximal and distal neck. A minimum neck length of at least 1.5 cm is required to allow secure anchoring of most stent grafts. The distance from the origins of the left subclavian artery and celiac axis to the aneurysm should be at least 1.5-3 cm to ensure that the stent graft does not inadvertently block these arteries. In an effort to reduce the incidence of paraplegia and to limit exclusion of intracostal arteries, the overall length of the stent graft is kept to a minimum.

Another important anatomic consideration is the size of the proposed conduit vessel (e.g., iliac) to ensure that it is adequate for accommodation of the stent-introducer system, which usually requires at least an 8-mm-diameter vessel. Where the pelvic vessels are less than 8 mm, either a retroperitoneal iliac or retroperitoneal aortic approach is utilized. The stent is the metallic framework to which the graft material is applied. Various balloon-expandable or self-expanding stents are available. For application in the thoracic aorta, stents of 30-40 mm in diameter (mean 35 mm) are required.

Typically, thoracic aortic aneurysm stent-graft procedures are performed in the cath lab (although some may be performed in the OR, depending on equipment availability and local politics), with the patient intubated and under GA. The cath lab is prepared for aortic surgery, with the patient placed on the table in a shallow right decubitus position. The patient’s thorax may be prepped and draped for a left thoracotomy. For an approach via the common femoral artery, the groin area is prepped for a femoral artery cutdown. When the iliac arteries are of insufficient size, the left
lower abdomen is prepped for a retroperitoneal approach to either the aorta or the common iliac artery. High-quality fluoroscopic equipment is essential to ensure accurate placement of the device, and a portable C-arm with digital subtraction capability is moved into position and centered over the thorax. When the iliac vessels are of sufficient size, a cutdown is performed on a femoral artery, the artery is punctured, and a guide wire is advanced into the thoracic aorta. A pigtail catheter is placed, and an aortogram is performed. The patient is then anticoagulated with iv heparin (100 IU/kg). A long, stiff guide wire is placed, and the 24 Fr sheath and dilator assembly is advanced over the wire until the sheath tip is proximal to the proximal aneurysm neck. The dilator and guide wire are withdrawn, and the stent graft is introduced into the sheath from its loading cartridge using the Teflon pusher. The device is pushed through the sheath until the stent graft approaches the tip of the sheath.

To reduce the likelihood of inadvertent downstream deployment of the stent graft caused by the force of blood flow during initial delivery, the arterial BP may be lowered to a mean of 50-60 mm Hg using SNP. Holding the pusher firmly in position, the sheath is rapidly withdrawn, and the stent graft expands into position. Rapid deployment helps to minimize distal migration of the stent graft. Immediately following deployment, the SNP is discontinued, allowing the BP to normalize. Repeat aortogram is performed, and any early leakage of contrast into the aneurysm is treated either with balloon angioplasty of the stent graft or further stent graft placement. Occasionally a faint, persistent leak of contrast is caused by leakage through the graft material. This typically ceases when the patient’s coagulation status returns to normal. Following removal of the delivery sheath, heparin is reversed with protamine sulfate, and the arteriotomy is repaired surgically. For stent placement through the retroperitoneal aorta, the procedure has a more extensive surgical component; however, the technique is similar.

The basic concept of abdominal aortic aneurysm (AAA) repair via an endovascular route is similar to the preceding section on thoracic aneurysm repair, with some notable exceptions. AAAs commonly arise inferior to the renal arteries, and 80-90% of cases involve either one or both iliac arteries. For this reason, stent grafts that can accommodate this more complicated anatomy are required. The superior aneurysm neck needs to be of sufficient length (1.5-2 cm) inferior to the most inferior renal artery to provide for stable anchoring. Inferiorly the stent graft must accommodate either or both iliac arteries. The procedure is performed in a two-stage fashion. Initially an aorta-tosingle-iliac-artery device is placed from the infrarenal aortic neck into one of the iliac vessels. A contralateral femoral artery puncture is then performed, and a catheter and guide wire are used to access an open stump of the stent graft from the contralateral limb. At this stage, a modular section of stent graft is placed from the aortic component into the contralateral limb; in this way, an aorta-to-bi-iliac graft is placed.

Usual preop diagnosis: Aortic aneurysm

▪ SUMMARY OF PROCEDURES

	Thoracic Aortic Aneurysms	Abdominal Aortic Aneurysms
Position	Supine/slight right decubitus	Supine
Incision	Femoral artery cutdown	Bilateral femoral artery cutdowns
Special instrumentation	Catheters, guide wires, sheaths, dilators, and stent grafts	⇚
Unique considerations	May require adjunctive procedure (e.g., brachial artery catheterization, balloon angioplasty, possible left subclavian-to-common carotid artery bypass procedure); iv heparin 100-300 IU/kg	⇚
Antibiotics	Cefazolin 1 g iv	⇚
Surgical time	1-3 h	⇚
Closing considerations	None	⇚
EBL	Usually minimal; however, can be up to 2-3	⇚
Postop care	ICU × 1 d	⇚
Mortality	3-5%	2-3%
Morbidity	Paraplegia: 2-3% Infection: 1% Surgical conversion: < 1%	Acute rupture: < 1% ⇚ ⇚
Pain score	3-4	3-4

ANESTHETIC CONSIDERATIONS

The anesthetic considerations for thoracic and abdominal stent-grafting are similar because the surgical techniques, complications, patient concurrent disease, and stent-graft deployment techniques are similar. Patients may be asymptomatic; most will have coexisting CAD, PVD, and/or cerebrovascular disease.

Suggested Readings

1. Baril D, Kahn R, Ellozy SH, et al: Endovascular abdominal aortic repair: emerging developments and anesthetic considerations. J Cardiothorac Vasc Anesth 2007; 21:730-42.

2. Makkad B, Pilling S: Management of thoracic aneurysm. Semin Cardiothorac Vasc Anesth 2005; 9:227-40.

3. Riddell JM, Black JH, Brewster DC, et al: Endovascular abdominal aortic aneurysm repair. Int Anesthesiol Clin 2005; 43: 79-91.

4. Ruppert V, Leurs LJ, Steckmeier B, et al: Influence of anesthesia type on outcome after endovascular aortic aneurysm repair: an analysis based on EUROSTAR data. J Vasc Surg 2006; 44:16-21.

PREOPERATIVE

Preop considerations for these patients are the same as for any patient undergoing repair of a descending thoracic aneurysm, abdominal aortic aneurysm, or aortobifemoral aneurysm. Many of these patients, however, are not suitable for conventional repair via a thoracotomy because of respiratory disease (e.g., FEV₁ < 1 L, severe COPD, PaCO₂ > 60 mm Hg), CAD, renal failure, CHF, or a combination of these factors. As such, they generally are at very high risk for periop morbidity and mortality. Before surgery the anesthesiologist should consult with the surgical and radiological teams to decide what will be done should a complication such as penetration or rupture of the aneurysm occur during surgery (typically, an emergency thoracotomy or laparotomy performed in the cath lab).

INTRAOPERATIVE

Anesthetic technique: Usually GETA (OLV may be required for emergency thoracotomy 2° ruptured thoracic aneurysm). Abdominal stent grafts may be placed under epidural or spinal anesthesia. Rarely, stent-grafting may be carried out with local anesthesia or MAC in patients unable to tolerate GA or epidural. In that case, the patient will come to the OR for removal of the introducer system and repair of the femoral artery.

Induction	Because these patients are typically extubated, the dose of fentanyl (5-10 mcg/kg) is limited to that which will suppress the hypertensive response to intubation, while still allowing for early extubation. The same considerations apply to the use of muscle relaxants (e.g., vecuronium [0.1 mg/kg] or rocuronium [1-1.5 mg/kg]). A DLT or a Univent ETT should be used, unless the team decides that a thoracotomy will not be performed under any circumstance.
Maintenance	Usually a balanced anesthetic technique of O2/air/isoflune or sevoflurane, supplemented with fentanyl (or remifentanil infusion) as needed. Hemodynamic control of BP (esmolol, SNP, NTG) and heart rate to avoid myocardial ischemia is important. Anesthetic management during stent-graft deployment: During stent-graft deployment, the aorta is momentarily occluded. Formerly, this resulted in a rapid ↑ BP → stent graft being moved from its intended position. The newer generations of stent grafts, using thermal or mechanical means for rapid deployment, cause minimal hemodynamic change, eliminating the need for aggressive BP control.
Emergence	Extubation is desirable, although hypothermia (< 34°C) may prevent this. Otherwise, aim for early extubation in the ICU. DLT (if used) may be replaced with a standard ETT at end of procedure if the patient is not extubated in the cath lab. Recovery is usually in the ICU.
Blood and fluid requirements	IV: 14-16 ga × 1 NS/LR @ 4-8 mL/kg/h PRBC available	Although usually minimal, blood loss can be considerable.
Monitoring	Standard monitors (p. B-1) Arterial line CVP catheter Urinary catheter TEE CSF pressure/drainage	Arterial line placement should be on the right as the radiologists may require access to the left brachial artery. CVP monitoring is usually sufficient. Central access for vasoactive drugs may be needed. TEE is used to aid in the identification of the thoracic aneurysm necks, to monitor deployment of the stent graft and to identify any continued flow of blood into the aneurysmal sac after deployment (endoleak). CSF drainage → ↓ CSF pressure may be necessary to minimize spinal cord ischemia (anterior spinal artery syndrome).
Positioning	[check mark] and pad pressure points [check mark] eyes	Supine ± slight right lateral decubitus
Complications	Hemorrhage	Hemorrhage at the groin site can be considerable and may be concealed.
	Vessel damage	Damage to the vessels (femoral, iliac, or abdominal aorta) during passage of the insertion system can occur with attendant massive hemorrhage.
	Rupture of aorta	Rupture or penetration of the thoracic aneurysm also can occur, necessitating rapid conversion to open thoracotomy.
	Deployment failure/incorrect position	The stent graft may deploy in an incorrect position or fail to fully deploy. This may require positioning of further stent grafts, balloon expansion of the stent graft, or conversion to thoracotomy.
	Hypothermia	Hypothermia can be a problem as a circulating-water warming blanket cannot be used on the operating table (use of fluoroscopy). Much of the patient’s body is exposed (upper-body Bair-Hugger usually okay), and a lower-body warming blanket cannot be used as the lower limbs may be ischemic during insertion of the stent graft.

POSTOPERATIVE

Complications

Aortic perforation/rupture Migration of grafts

Femoral artery dehiscence Distal embolization Paraplegia

Requires emergency surgery. → loss of distal pulses, mesenteric ischemia, acute renal insufficiency. Requires prompt return to OR. [check mark] pulses; angiography/surgical intervention. [check mark] reflexes; prompt return to OR.

Pain management

Minimal analgesic requirements

If groin incision, local anesthetic infiltration may be used.

Tests

As indicated by patient condition.

CT scan, angiogram prior to discharge and at regular intervals following discharge.

Suggested Readings

1. Coady MA, Ikonomidis JS, Cheung AT, et al: A surgical management of descending thoracic aortic disease: open and endovascular approaches: a scientific statement from the American Heart Association. Circulation 2010; 121:2780-804.

2. Crimi E, Lee JT, Dake MD, van der Starre PJ: Transesophageal echocardiography guidance for stent-graft repair of a thoracic aneurysm is facilitated by the ability of partial stent deployment. Ann Vasc Surg 2012; 26(6):861.e7-9.

3. Dake MD, Miller DC, Semba CP, et al: Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms. N Engl J Med 1994: 331(26):1729-34.

4. Findeiss LK, Cody ME: Endovascular repair of thoracic aortic aneurysms. Semin Intervent Radiol 2011; 28(11):107-17.

5. Fleck T, Hutschala D, Weissl M, et al: Cerebrospinal fluid drainage as a useful treatment option to relieve paraplegia after stent-graft implantation for acute aortic dissection type B. J Thorac Cardiovasc Surg 2002; 123:1003-5.

6. Foley OJ, Criado FJ, Farber MA, et al: VALOR Investegators: Long-term results with the Talent thoracic stent graft in the VALOR trial. J Vasc Surg 2012; 56:1214-21.

7. Herold U, Piotrowski J, Baumgart D, et al: Endoluminal stent graft repair for acute and chronic type B aortic dissection and atherosclerotic aneurysm of the thoracic aorta: an interdisciplinary task. Eur J Cardiothorac Surg 2002; 22:891-7.

8. Miller DC: Through the looking glass: the first 20 years of thoracic aortic stent-grafting. J Thorac Cardiovasc Surg 2013; 145:S142-8.

9. Mitchell RS, Dake MD, Semba CP, et al: Endovascular stent-graft repair of thoracic aortic aneurysms. J Thorac Cardiovasc Surg 1996; 111(5):1054-62.

10. Schutz W, Gauss A, Meierhenrich R, et al: Transesophageal echocardiographic guidance of thoracic aortic stent-graft implantation. J Endovasc Ther 2002; 9:14-9.

REPAIR OF ACUTE AORTIC DISSECTIONS

SURGICAL CONSIDERATIONS

Description: Repair of acute aortic dissection is performed to prevent life-threatening complications such as hemorrhage, tamponade, and heart failure 2° acute aortic valvular insufficiency and to redirect flow into the true lumen. Emergent repair of acute ascending dissections is generally accepted therapy to prevent rupture of the aortic root with exsanguination or pericardial tamponade. Mortality for acute ascending dissection is estimated at 1% per hour for the first 48 hours. The management of descending thoracic aortic dissections remains controversial, but surgical intervention probably should be recommended only for younger patients, patients with uncontrolled pain or evidence for continued expansion or extravasation, and those with branch-vessel compromise.

Ascending aortic dissections typically produce sharp, tearing retrosternal pain that penetrates straight through to the subscapular area. The presentation, however, is so frequently variable that any patient in extremis, especially with migratory pain or vacillating findings, and even asymptomatic patients with valvular aortic regurgitation (AR), should be considered for the diagnosis. With a suggestive Hx, a new murmur, or a pulse deficit, an enlarged mediastinal shadow on chest radiography should prompt further diagnostic efforts. CT scanning, MRI, and aortography may all be diagnostic, but no diagnostic modality has 100% sensitivity. TEE appears to be highly sensitive in detecting a mobile intimal flap in the ascending or descending aorta. In addition, TEE can provide useful information regarding AR, periaortic hematoma, and flow within a false channel. It is usually available at the bedside or in the emergency ward and does not subject the patient to a contrast load.

After the patients are diagnosed, they are transported immediately to the OR. Through a median sternotomy, venous access is gained via the right atrium, and arterial inflow is supplied through a femoral artery or axillary artery. CPB is established, the patient cooled to 18°C, and circulatory support discontinued although antegrade or retrograde cerebral perfusion may be employed. During a period of circulatory arrest, antegrade or retrograde cerebral perfusion, the ascending aorta is opened and the tear localized. The repair is carried distally into the arch, if the entire dissection can be resected, and the distal aortic layers are reapproximated with a Teflon felt strip supporting the medial and adventitial layers. The distal graft anastomosis is then completed, the graft clamped, the bypass pump restarted, and systemic warming commenced. Proximally, the aortic root is reconstructed, again using Teflon felt to support the medial and adventitial layers and to resuspend the aortic valve, which can be salvaged in approximately 85% of cases. The heart is then cleared of air and
the cross-clamp removed to allow reperfusion of the coronary circulation. After a sufficient period of resuscitation, the patient is weaned from CPB. Aggressive management of an acquired coagulopathy is not unusual prior to chest closure.

Figure 6.3-3. The three classification systems of aortic dissection and the distribution of the intimal tear.

Repair of dissections involving the descending thoracic aorta is accomplished through a left thoracotomy utilizing partial CPB. Venous drainage is usually via the femoral vein, although the pulmonary vein may be used for partial or “left-heart” CPB. Arterial access is via the femoral artery. After institution of CPB, the dissected aorta above and below the most damaged area is cross-clamped and the aorta transected. After oversewing patent intercostal arteries, the medial and adventitial layers are buttressed with Teflon felt, and an interposition Dacron graft is sewn into place. After evacuation of air, clamps are removed, and the patient weaned from CPB. Heparin reversal, decannulation, and closure are accomplished in the usual manner.

Usual preop diagnosis: Acute dissection of the aorta (See Fig. 6.3-3 for types of dissection.)

▪ SUMMARY OF PROCEDURES

	Ascending Aorta	Descending Aorta
Position	Supine	Lateral decubitus, left side up
Incision	Median sternotomy	Left lateral thoracotomy
Unique considerations	Full hemodynamic monitoring, with provisions for circulatory arrest, profound hypothermia, barbiturates and steroids; TEE	DLT; CPB; TEE; lumbar drain
Antibiotics	Cefazolin 1 g iv	⇚
Surgical time	Cross-clamp: 30-50 min Circulatory arrest: 20-30 min CPB: 60-100 min Total: 3-5	⇚ 30-60 min — 35-60 min ⇚
Closing considerations	Aggressively treat coagulopathy (frequently 2° ↓ Plt).	Replace DLT with single-lumen ETT.
EBL	400-800 mL	600-800 mL
Postop care	ICU: 1-2 d, intubated	⇚
Mortality	10-25%	⇚
Morbidity	Bleeding: 3-8% Respiratory insufficiency: 2-5% CVA: 2-4%	Paraplegia: 5% CVA: 1-2% MI: 1-2%
Pain score	7-10	9-10

ANESTHETIC CONSIDERATIONS

PREOPERATIVE

Sx are usually of sudden onset and depend on the site of dissection and specific organ involvement. Aortic dissections are divided into 2 types, depending on the site of intimal tear: Type A—ascending and aortic arch, and Type B— descending aorta (Fig 6.3-3). Initial treatment involves the use of antihypertensive medications (e.g., SNP) to control BP and β-blockers (e.g., esmolol) to ↓ contractility. Type A dissections usually require urgent surgery. Patients presenting electively for thoracotomy (descending aorta) may have a thoracic epidural catheter placed the night before surgery. These patients are only heparinized during the procedure.

Respiratory	[check mark] for recurrent laryngeal nerve palsy with chronic aneurysmal dilation. Tracheal and left main bronchus compression → difficult intubation, atelectasis; hemoptysis 2° rupture into lung; hemothorax → compromised oxygenation, ↑ intrathoracic pressure →↓ venous return, especially with IPPV. Tests: CXR: [check mark] for widened mediastinum, tracheal or left main bronchus compression and distortion (affects DLT placement), atelectasis, pleural effusion (or hemothorax 2° rupture).
Cardiovascular	Aortic dissections may be associated with chronic HTN, cystic medial necrosis, or other connective tissue disorder (e.g., Marfan syndrome) and trauma. Dissection may result in cardiac tamponade, acute aortic valve incompetence, acute cardiac failure, angina, MI, or rupture of the aorta. Dissection of major arteries may result in ↓ or absent peripheral pulses, which may affect the placement sites for intraarterial monitoring and central venous access. Pain and anxiety may result in HTN, while rupture or leakage may result in ↓ BP and shock. Tests: ECG: [check mark] for Sx of LVH, ischemia or infarction, low voltage (tamponade). ECHO: [check mark] for site of dissection, valvular competence, LV function, pericardial effusion, or tamponade. Angiography: [check mark] for site of dissection (Type A or B), valvular function, involvement of coronary and other major arteries, sites of rupture, LV function. CT scan: [check mark] site and extent of dissection.
Neurological	Deficits are not uncommon, especially with Type B dissections where the blood supply to the spinal cord may be jeopardized. Document preop exam carefully.
Renal	Renal failure 2° renal artery involvement in dissection, shock, or cardiac failure. UO should be monitored closely during initial medical therapy. Tests: UO; BUN; Cr; electrolytes
Gastrointestinal	Compromised blood supply to the bowel or liver may result in ischemia → metabolic acidosis and ↓ liver function. Tests: Consider ABG: [check mark] persistent metabolic acidosis; LFTs, if indicated by H&P.
Hematologic	Coagulopathy may be present 2° massive hemorrhage or liver involvement and can increase risk of the surgery. Tests: PT; PTT; Hct/Hb
Laboratory	Other tests as indicated from H&P
Premedication	Because many of these patients present emergently, consider full-stomach precautions: H2-antagonists (ranitidine 50 mg iv), metoclopramide (10-20 mg iv), antacids (Na citrate 0.3 M 30 mL po). Alleviate anxiety and pain (midazolam 0.025-0.05 mg/kg iv), which may worsen HTN, but avoid obtundation.

INTRAOPERATIVE

Anesthetic technique: GETA ± thoracic epidural. Preinduction control of BP and contractility (NTG or SNP to SBP = 105-115 and esmolol to HR = 60-80) is important in preventing extension of the dissection or rupture of the aneurysm. Fluid resuscitation may be necessary prior to induction.

Induction	Control of hypertensive response to laryngoscopy and intubation is important and may be accomplished with moderate-dose narcotic (fentanyl 10-15 mcg/kg or sufentanil 1-2 mcg/kg) and etomidate (0.1-0.3 mg/kg), esmolol (5-10 mg iv bolus), or SNP (25-50 mcg bolus). Pretreatment with lidocaine (1.5 mg/kg) also may be required to further control the hypertensive response to laryngoscopy. Muscle relaxation may be obtained using vecuronium (0.1 mg/kg) or rocuronium (1-2 mg/kg). Remember the possibility of a full stomach in this patient population. Hence, a modified rapid-sequence induction (cricoid pressure with manual ventilation and NMR) may achieve the two goals of relatively rapid induction and intubation and tight control of BP. Usually a left DLT is used in patients with descending lesions to improve surgical access; however, it may be difficult to place due to aneurysmal compression of the trachea and left mainstem bronchus, and it is associated with a small risk of aneurysmal rupture. For these reasons, a right DLT may be preferred. FOB is mandatory to verify ET placement.
Maintenance	O₂/narcotic/benzodiazepine: low-dose volatile agent (isoflurane [0.3-0.5%] or sevoflurane [0.5-1%]) may be used to control BP (MAP = 60-80), although infusion of vasopressors, vasodilators, or inotropes may be necessary. Control HR (< 80; anesthesia, esmolol) and contractility (β-blockade or inotropes, depending on circumstances). Benzodiazepines may be used for amnesia (midazolam 100 mcg/kg). If thoracic epidural in place, fentanyl (20-30 mcg/kg) or sufentanil (4-6 mcg/kg) may be used. Most Type A aneurysms and ascending/arch aneurysms require hypothermic CPB (see Anesthetic Considerations for Cardiopulmonary Bypass, p. 350). Intraop anesthetic considerations are governed primarily by the site of the aortic pathology. These considerations are discussed below.
Emergence	Transported to ICU, sedated, intubated, and ventilated × 24-48 h. Following repairs of the descending aorta (thoracotomy incision), weaning from ventilator may be aided by epidural narcotics after documentation of normal spinal cord function and coagulation.
Blood and fluid requirements	Anticipate large blood loss. IV: 14 ga – 7 Fr × 2 NS/LR @ 6-8 mL/kg/h Warm all fluids. Humidify gases. Cross-match 6-8 U of blood. UO 0.5-1 mL/kg/h	In Type A dissections and arch aneurysms, if possible, avoid iv placement in the left arm or left IJ/subclavian veins because of the possibility of innominate vein ligation. Mannitol (0.25-0.5 g/kg iv) should be given if renal perfusion is compromised by dissection or before cross-clamping. Consider normovolemic hemodilution if the patient is stable and the Hct > 35. After unclamping: furosemide (1 mg/kg), if hemodynamically stable.
Monitoring	Standard monitors (p. B-1). Arterial line CVP, PA catheter (optional) Urinary catheter	Arterial line site is dependent on type of surgery and location of the lesion. Because the right subclavian artery may be compromised in patients with ascending lesions, the left radial or femoral arteries may need to be used. Aortic arch lesions may involve the vascular supply to both upper extremities; hence, femoral artery catheterization may be necessary. In ascending lesions, two artery lines may be required—right radial (above clamp pressure) and left femoral (below clamp pressure). Consult with surgeon as to best site.
	TEE	TEE is useful to assess cardiac function, regional wall motion abnormalities, valvular pathology, aortic valvular repair (if required as part of a Type A repair). Probe passage may increase compression of the trachea, impeding ventilation. Caution should be used in the presence of aneurysmal compression of the esophagus.
	Temperature	Monitor both core (esophageal/bladder) and tympanic membrane T (as indicative of brain T)—important in deep hypothermic arrest.
	EEG/EP (arch/ascending lesions)	EEG/EP may help in assessing effectiveness of cerebral protection or adequacy of cerebral perfusion.
	SSEPs/MEPs (descending lesions)	SSEPs may detect posterior spinal perfusion problems, while MEPs may detect anterior cord dysfunction. Both EEG and EPs may require expert help to set up, monitor, and interpret.
	Cerebral oximetry	Cerebral oximetry may be helpful in detecting changes in cerebral blood flow after cannulation of the innominate artery.
Complications	Hemorrhage Coagulopathy	Both are common. Hemorrhage should be treated with crystalloid, colloid, or blood products, as indicated.
Ascending lesions	CPB AR Coronary arteries Deep hypothermic arrest	Usual site of cannulation for CPB is the ascending aorta, axillary, or femoral arteries. Aortic valve replacement may be necessary. Patients may have myocardial ischemia 2° coronary artery occlusion; may require CABG or reimplantation of vessels. Cerebral protective measures and selective perfusion of cerebral vessels may be required. (See below.)
Arch lesions	CPB Deep hypothermic arrest	Usual site of cannulation for CPB is femoral or axillary artery. Cerebral protection relies on hypothermia (20-22°C) and drugs (hydrocortisone 100 mg iv or dexamethasone 8 mg iv) to reduce CMRO2 and neuronal injury. The head is surface cooled (protect eyes and ears from cold injury). EEG may be monitored to ensure absence of brain electrical activity. Monitor tympanic membrane T as an indication of brain T. Avoid hyperglycemia and maintain normal pH and PaCO2 when measured at 37°C (alpha stat). Maintain muscle relaxation.
Descending lesions	Precross-clamping	Mannitol (0.5 g/kg) and furosemide (20-40 mg iv) should be given before clamp application to provide renal protection, even if a shunt is placed. Hypothermia (32-34°C) may protect spinal cord.
	Shunt	A heparin-bonded shunt may be used from the aortic arch to the femoral artery to provide distal perfusion.
	Partial bypass	Partial CPB may be used to provide distal perfusion. In this arrangement, the heart perfuses the head and upper extremities, while CPB is used to perfuse and oxygenate the lower body. Venous drainage is from the femoral vein, PA, or left atrium and returned via the femoral artery. Distal and proximal pressures are altered by controlling cardiac filling, pump flow, and vasodilators.
	Cross-clamping	Application of clamp may → acute HTN with ischemia and LV failure. This may be controlled by partial bypass, shunting or use of vasodilators (SNP 0.5-2 mcg/kg/min, NTG 0.5-2 mcg/kg/min). During cross-clamping, monitor UO and [check mark] metabolic acidosis (renal or bowel ischemia) with serial ABGs. Cross-clamp time should be < 30 min to reduce incidence of paraplegia. The surgeons often request that a lumbar CSF drain be inserted to ↓ CSF pressure (to ≤ CVP) and, thus, improve spinal cord blood flow.
	Unclamping	Unclamping may result in severe ↓ BP and myocardial depression. Hypovolemia, acidosis, vasoactive factors, and reactive hyperemia have been implicated as the cause. Prior to unclamping, ensure adequate volume status (CVP and/or PCWP 2-5 mm Hg above patient’s normal); treat acidosis; have vasopressors available; and the clamp should be released slowly over 1-2 min. Use of partial bypass or a shunt to ensure distal perfusion will mitigate unclamping shock. When hemodynamically stable, give furosemide (1 mg/kg iv). Inotropes (dopamine) may be needed to support circulation.
Positioning	[check mark] eyes [check mark] and pad pressure points Arch and ascending: supine, shoulder roll Descending: lateral decubitus, axillary roll, pillow between knees

POSTOPERATIVE

Complications

Myocardial ischemia, CHF Dysrhythmias Hemorrhage Coagulopathy Renal failure Bowel ischemia Respiratory failure Paraplegia

A DLT may be required in lesions of the descending aorta, if hemorrhage continues from left lung; otherwise, the tube may be replaced at the end of procedure by a single-lumen ETT. BP should be controlled to MAP 60-80 and HR < 100 to decrease the likelihood of repeat dissection, bleeding, or graft dehiscence.

Anterior spinal artery syndrome

Pain management

PCA (p. E-4) Epidural (p. E-6)

Thoracic epidural catheter may be used in patients following thoracotomy if coagulation status normal.

Tests

ECG: ischemia, infarction, dysrhythmias CXR: line and ETT placement; pulmonary contusion Coagulation profile Renal: BUN, Cr ABG: Respiratory, gut ischemia CT scan: CNS or spinal neurologic deficits Electrolytes

Suggested Readings

1. Atkins MD Jr, Black JH III, Cambria RP: Aortic dissection: perspective in the era of stent-graft repair. J Vasc Surg 2006; (Suppl A):30A-43A.

2. Dong CCJ, MacDonald DB, Janusz MT: Intraoperative spinal cord monitoring during descending thoracic and thoracoabdominal aneurysm surgery. Ann Thorac Surg 2002; 74:S1873-6.

3. Dorotta I, Kimball-Jones P, Applegate R: Deep hypothermia and circulatory arrest in adults. Semin Cardiothorac Vasc Anesth 2007; 11:66-76.

4. Estrera AL, Miller CC, Goodrick J, et al: Update on outcomes of acute type B aortic dissection. Ann Thorac Surg 2007; 83:S842-5.

5. Fann JI, Smith JA, Miller DC, et al: Surgical management of aortic dissection over a 30-year period. Circulation 1995; 92(II):113-21.

6. Fattori R, Mineo G, Di Eusano M: Acute type B aortic dissection: current management strategies. Curr Opin Cardiol 2011; 26:488-93.

7. Hughes GC, Andersen ND, McCann RL: Management of acute type B aortic dissection. J Thorac Cardiovasc Surg 2013; 145:S202-7.

8. Knipp BS, Deeb GM, Prager RL, et al: A contemporary analysis of outcomes for operative repair of type A aortic dissection in the United States. Surgery 2007; 142:524-8.

9. Kohl BA, McGarvey ML: Anesthesia and neurocerebral monitoring for aortic dissection. Semin Thorac Cardiovasc Surg 2005; 17:236-46.

10. Kruger T, Conzelmann LO, Bonser RS, et al: Acute aortic dissection type A. Br J Surg 2012; 99:1331-1344.

11. Kruger T, Weigang E, Hoffmann I, Blettner M, Aebert H: GERAADA Investegators: cerebral protection during surgery for acute aortic dissection type A: results of the German Registry for Acute Aortic Dissection Type A (GERAADA). Circulation 2011; 124:434-43.

12. Lips J, de Haan P, de Jager S, et al: The role of transcranial motor evoked potentials in predicting neurologic and histopathologic outcome after experimental spinal cord ischemia. Anesthesiology 2002; 97:183-91.

13. Lu S, Sun X, Hong T, et al: Bilateral versus unilateral antegrade cerebral perfusion in arch reconstruction for aortic dissection. Ann Thorac Surg 2012; 93:1917-20.

14. Olsson C, Thelin S, Stahle E, et al: Thoracic aortic aneurysm and dissection: increasing prevalence and improved outcomes reported in a nationwide population-based study of more than 14,000 cases from 1987 to 2002. Circulation 2006; 114:2611-8.

15. Penco M, Paparoni S, Dagianti A: Usefulness of transesophageal echocardiography in the assessment of aortic dissection. Am J Cardiol 2000; 86:53G-56G.

16. Szeto WY, Gleason TG: Operative management of ascending aortic dissections. Semin Thorac Cardiovasc Surg 2005; 17: 247-55.

REPAIR OF ANEURYSMS OF THE THORACOABDOMINAL AORTA

SURGICAL CONSIDERATIONS

Description: Aneurysms of the thoracoabdominal aorta (TAAA) may occur because of degenerative aortic disease (atherosclerosis), as a consequence of hereditary disorders of metabolism (Marfan syndrome), or as a sequela of chronic aortic dissections. These aneurysms are classified into four types (Fig 6.3-4) that occur with equal frequency: Type I consists of aneurysms that involve most of the descending thoracic and upper abdominal aorta. Type II involves most of the descending thoracic aorta and most or all of the abdominal aorta. Type III involves the distal thoracic and varying segments of the abdominal aorta. Type IV involves most or all of the abdominal aorta, including the origins of the visceral vessels.

Repair of these aneurysms is an extensive, difficult, and demanding procedure, as blood flow to the entire body below the neck is interrupted, with resultant renal and visceral ischemia. In addition, the blood supply to the spinal cord may arise from lumbar and/or intercostal vessels in the affected aortic segment, producing critical cord ischemia during cross-clamping and postop paraplegia.

Almost all thoracoabdominal aneurysm repairs are performed through a thoracoabdominal incision (Fig. 6.3-5) using the inclusion technique (Fig. 6.3-6) as advocated by Crawford et al. After opening the chest, the incision is extended across the costal cartilage onto the abdomen. The diaphragm is radially incised to the aortic hiatus, and the retroperitoneal dissection plane established anterior to the psoas musculature. All intraabdominal contents, as well as the left kidney, are reflected anteriorly (Fig. 6.3-6). Only proximal aortic control is established. After minimal heparinization, OLV is established to allow collapse of the left lung, the proximal aorta at the aneurysm neck is cross-clamped, and the aneurysm is incised. Back-bleeding from patent intercostal, mesenteric, and renal vessels can be controlled by balloon catheters, and aggressive blood salvage with autotransfusion devices is mandatory. The repair entails suturing a tube graft proximally to the divided aorta and then sewing islands of aortic tissue containing
intercostal visceral vessels onto appropriate-sized holes in the side of the tube graft. This allows reperfusion of important intercostal, celiac axis, superior mesenteric, renal arteries, and finally, the distal aorta or iliac arteries. Because there is obligate visceral ischemia during the period of cross-clamping (which must be limited to < 60-75 min), the operation must proceed expeditiously.

Figure 6.3-4. Crawford’s classification of thoracoabdominal aortic aneurysms (TAAA). (Reproduced with permission from Baker RJ, Fischer JE: Mastery of Surgery, Vol 2. Lippincott Williams & Wilkins, Philadelphia: 2001.)

Figure 6.3-5. Lateral A: and frontal B: views of the thoracoabdominal incisions used for repair of type IV (W, X), type III (Y, Z), and types I and II (Z) TAAAs. (Reproduced with permission from Baker RJ, Fischer JE: Mastery of Surgery, Vol 2. Lippincott Williams & Wilkins, Philadelphia: 2001.)

Figure 6.3-6. During the inclusion technique, the anterior renal fascia is opened and the kidney is mobilized, along with the upper abdominal organs (on the left). (Reproduced with permission from Wind GG, Valentine RJ: Anatomic Exposures in Vascular Surgery. Williams & Wilkins, Baltimore: 1991.)

Alternatively, in an effort to afford both spinal cord and visceral protection through hypothermia, the operation may be performed on CPB during a period of profound hypothermic circulatory arrest, which may exacerbate hemorrhagic complications.

After aortic cross-clamping, the aneurysm is opened and the repair performed from within the aneurysm, sewing on-lay patches of the intercostal, mesenteric, and renal vessels to openings created in the tube graft. This no-clamp technique allows reasonable management of these very extensive aneurysms, but results in an obligatory and ongoing blood loss through back-bleeding of visceral vessels until the anastomoses are complete.

Usual preop diagnosis: Expanding, painful, or large thoracoabdominal aneurysm

▪ SUMMARY OF PROCEDURE

Only gold members can continue reading. Log In or Register to continue

Tags: Anesthesiologist's Manual of Surgical Procedures

May 23, 2016 | Posted by drzezo in ANESTHESIA | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access

Position	Right lateral decubitus; hips rotated posteriorly to 45° and left arm draped forward over an airplane sling. Axillary roll placed. (See Fig. 6.3-5A.)
Incision

Anesthesia Key

Fastest Anesthesia & Intensive Care & Emergency Medicine Insight Engine

Vascular Surgery

Related

Full access? Get Clinical Tree

Anesthesia Key

Fastest Anesthesia & Intensive Care & Emergency Medicine Insight Engine

Vascular Surgery

Share this:

Related

Related posts:

Full access? Get Clinical Tree