Anesth Analg 2003;97:1254-1266
© 2003 International Anesthesia Research Society
CARDIOVASCULAR ANESTHESIA
Diagnosis of an Intraoperative Aortic Dissection by Transesophageal Echocardiography During Routine Coronary Artery Bypass Grafting Surgery
Dominic J. Cottrell, MD,
E. Stuart Cornett, MD,
Marc S. Seifer, MD,
Edward H. Kincaid, MD, and
David A. Zvara, MD
Departments of Anesthesiology and Cardiothoracic Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina
Address correspondence to David A. Zvara, MD, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157–1009. Address email to dzvara{at}wfubmc.edu
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Abstract
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Acute aortic dissection during coronary artery bypass grafting (CABG), though rare, causes significant morbidity and mortality. We report a case of postcardiopulmonary bypass aortic dissection in a 73-yr-old man who presented for CABG. The diagnosis was made by transesophageal echocardiography and allowed immediate treatment of the potentially lethal complication.
IMPLICATIONS: Acute aortic dissection during coronary artery bypass grafting (CABG), though rare causes frequent morbidity and mortality. We report a case of postcardiopulmonary bypass aortic dissection in a 73-yr-old man who presented for CABG. Diagnosis made by transesophageal echocardiography allowed immediate treatment of the potentially lethal complication.
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Introduction
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Acute aortic dissection during operations involving aortic cannulation and cardiopulmonary bypass (CPB) is a rare complication with an incidence of approximately 0.16% (1). Despite the relative infrequency of this event, this complication must be diagnosed quickly, as it is associated with a mortality of 20%–78% depending on the time of diagnosis (1,2). We report a case of an acute aortic dissection promptly diagnosed by transesophageal echocardiography (TEE) in a low-risk patient undergoing routine coronary artery bypass grafting (CABG) surgery. This case is distinctive not only in that the dissection occurred immediately after termination of CPB and was rapidly diagnosed but also because other authors have only reported the use of TEE in aortic dissections after complicated valve surgery (3,4). This added benefit of TEE has not been documented in routine CABG surgery.
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Case Reports
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A 73-yr-old male with no history of hypertension, congenital aortic medial disease, or bicuspid aortic valve underwent four-vessel CABG with CPB under general endotracheal anesthesia. After induction, a pulmonary artery catheter and a 5.0-MHz Hewlett-Packard Omniplane TEE probe were placed without complications. The pre-bypass TEE examination revealed good left ventricular (LV) function and a normal ascending thoracic aorta (Fig. 1).
Standard distal ascending aortic and right atrial cannulae, a LV vent and a retrograde cardioplegia cannula were inserted. After an uneventful 144-min CPB period and four-vessel CABG with a cross-clamp time of 59 min, the patient was re-warmed and weaned from CPB without inotropic support. Blood pressure, initially 130/75 mm Hg, decreased to 80/40 mm Hg 10 min after termination of CPB. Just before this time the surgeons removed the venous cannula and protamine reversal was being considered. The right radial arterial waveform remained intact despite the hypotensive event. The aortic cannula, however, had not been removed, and the sternal retractors also remained in place. Immediate TEE evaluation revealed good LV function and the presence of an intimal flap near the aortic annulus extending approximately 4 cm into the ascending aorta (Figs. 2 and 3). The patient was immediately returned to full CPB and actively cooled for deep hypothermic circulatory arrest. On opening the aorta, the intimal tear was identified in the aortic arch, opposite the left common carotid artery. The dissection was repaired with a 24-mm Dacron graft and the second CPB period lasted 125 min, with 28 min of circulatory arrest. The patient was weaned from CPB with epinephrine, and hemostasis was obtained with protamine administration. The postoperative course was uneventful and he was discharged home on postoperative day 5 in good condition with a normal neurologic status.
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Discussion
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Acute intraoperative aortic dissection after cardiac surgery with CPB is a rare yet catastrophic event. In two large reviews involving a combined 21,820 patients having cardiac surgical procedures with CPB, the incidence of acute aortic dissection was 0.16% and 0.35% (1,2). Although rare, the mortality from the event ranged from 20% to 78% depending on the timing of initial diagnosis. In a review of 14,877 patients with 24 dissections, Still et al. (1) reported 20% mortality in patients diagnosed with a dissection while still in the operating room and a 50% mortality in patients whose injuries were discovered after operation. Similarly, Murphy et al. (2) reported 6943 patients with 15 dissections. In this group, the early detection and repair was associated with a 33% mortality rate; late diagnosis after operation was associated with a 78% mortality rate. Our case is important because it uniquely demonstrates the added diagnostic benefit of TEE in routine CABG surgery, specifically facilitating early diagnosis of aortic dissection.
Cardiac surgery remains among the highest-risk operative procedures. We believe that routine TEE provides an added margin of safety. The information obtained from TEE examination, including LV systolic and diastolic function, chamber sizes, and wall motion abnormalities, as well as valve anatomy and function, outweigh the small risk of TEE probe placement. In addition, the ability to rapidly diagnose lethal, albeit rare, complications such as aortic dissection as well as to identify previously unknown conditions such as severe aortic atherosclerotic disease belies the added benefit exemplified by our case report.
Risk factors for aortic dissection include long-standing hypertension, age >50 yrs, cystic medial necrosis of the arterial wall, severe atherosclerosis, Marfan’s syndrome, and a history of aortic coarctation. Retrograde femoral artery catheterization for arteriography, CPB, or intraaortic balloon counterpulsation has been recognized as a risk factor for acute aortic dissection (5,6). During cardiac surgery with CPB, however, up to 93% of dissections involve aortic cannulation, aortic cross-clamping, and partial occlusion clamps (1). In our patient, the dissection site was located distal to the aortic cannulation site. Although it is unclear why dissection occurred in this location, aortic cannula flow, repositioning of the cross-clamp, or other surgical injury could be implicated.
Acute aortic dissection can sometimes be diagnosed by surgical inspection of the aorta that reveals an enlarged or expanding segment with hematoma or discoloration. Smaller dissections may not be immediately obvious, however, and TEE may provide the most effective means of diagnosis (7). Because of the sudden onset of hypotension, a dissection was certainly suspected in our case, but valve dysfunction or LV dysfunction was also being excluded. Because we did not allow the dissection to progress, it is difficult to speculate whether the diagnosis could have been made without a TEE examination. Additionally, the time and risk required to obtain a probe and machine and then place it safely in an anticoagulated patient in the presence of undiagnosed hypotension would be unacceptable.
TEE use for diagnosis of acute aortic dissection has been previously reported. Troianos et al. (3) reported their experience in 3 patients presenting for complex valvular repair and subsequent aortic dissection of the ascending aorta. In an unusual case report involving a patient presenting for mitral valve repair, Varghese et al. (4) described the intraoperative diagnosis of an aortic dissection involving the descending thoracic aorta. In both reports, the importance of TEE as a diagnostic tool was emphasized. According to a survey of anesthesiologists by Morewood et al. (8), TEE is used in approximately 90% of complex valve operations but during as few as 41% of routine CABG procedures.
In conclusion, we present a case of acute aortic dissection in a low-risk patient having routine CABG surgery. The etiology of early post-CPB hypotension was immediately diagnosed with a focused TEE examination. Previous large series reports suggest that good patient outcome depends largely on early recognition and management of this rare, yet often fatal, complication. Our routine use of TEE in all patients presenting for cardiac surgery with CPB allowed us to diagnose the dissection and successfully treat this patient.
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Footnotes
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Supplemental material available at www.anesthesia-analgesia.org.
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References
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- Still RJ, Hilgenberg AD, Akins CW, et al. Intraoperative aortic dissection. Ann Thorac Surg 1992; 53: 374–80.[Abstract]
- Murphy DA, Craver JM, Jones EL, et al. Recognition and management of ascending aortic dissection complicating cardiac surgical operations. J Thorac Cardiovasc Surg 1983; 85: 247–56.[Abstract]
- Troianos C, Savino JS, Weiss RL. Transesophageal echocardiographic diagnosis of aortic dissection during cardiac surgery. Anesthesiology 1991; 75: 149–53.[ISI][Medline]
- Varghese D, Riedel BJ, Fletcher SN, et al. Successful repair of intraoperative aortic dissection detected by transesophageal echocardiography. Ann Thorac Surg 2002; 73: 953–55.[Abstract/Free Full Text]
- Saito T, Fuse K, Kato M, Misawa Y. Retrograde aortic dissection during cardiopulmonary bypass a case report successfully treated by contralateral femoral cannulation [in Japanese]. Nippon Kyobu Geka Gakkai Zasshi 1996; 44: 1953–7.[Medline]
- Tanemoto K, Kuinose M, Kanaoka Y. Complications of femoral artery cannulation in aortic arch related operations [in Japanese]. Nippon Kyobu Geka Gakkai Zasshi 1994; 42: 306–10.[Medline]
- Yalçin F, Thomas JD, Homa D, Flachskampf FA. Transesophageal echocardiography: first-line imaging for aortic diseases. Cleve Clin J Med 2000; 67: 417–8,421–8,[Medline]
- Morewood GH, Gallagher ME, Gaughan JP, Conlay LA. Current practice patterns for adult perioperative transesophageal echocardiography in the United States. Anesthesiology 2001; 95: 1507–12.[ISI][Medline]
Accepted for publication June 12, 2003.
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Abstract
Introduction
