Ann Thorac Surg 2001;71:777-781
© 2001 The Society of Thoracic Surgeons
Original article: cardiovascular
Coronary artery bypass combined with bilateral carotid endarterectomy
Mark Dylewski, MDa,
Charles C. Canver, MDa,
Jyotirmay Chanda, MD, PhDa,
R. Clement Darling, III, MDb,
Dhiraj M. Shah, MDb
a Division of Cardiothoracic Surgery, Albany Medical College, Albany, New York, USA
b Division of Vascular Surgery, Albany Medical College, Albany, New York, USA
Accepted for publication October 18, 2000.
Address reprint requests to Dr Canver, Division of Cardiothoracic Surgery, Albany Medical College, 47 New Scotland Ave, Mail Code 55, Albany, New York 12208-3479
e-mail: canverc{at}mail.amc.edu
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Abstract
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Background. Surgical management of patients presenting for coronary artery bypass grafting with significant bilateral carotid artery stenosis has not been well defined. In this study, our preliminary results of coronary artery bypass grafting with concomitant bilateral carotid endarterectomy have been reviewed.
Methods. A retrospective nonrandomized chart review was performed in 33 patients with unstable angina and bilateral carotid artery stenosis, more than 70%, undergoing simultaneous coronary artery bypass grafting and bilateral carotid endarterectomy using an eversion technique.
Results. Concomitant coronary artery bypass grafting with bilateral carotid endarterectomy was performed urgently in 24 (73%) and electively in 9 (27%) patients. The average carotid artery cross-clamp and total perfusion times were 14.7 ± 4.9 minutes and 123 ± 29.2 minutes, respectively. The average length of stay in the cardiopulmonary intensive care unit was 4.2 ± 14.2 days and total hospital stay was 16.2 ± 20.5 days. Postoperative in-hospital stay was 14.9 ± 20.3 days. There were no postoperative strokes. Twenty-one (64%) patients were discharged before the tenth postoperative day. Nonfatal postoperative complications occurred in 27% (9 of 33) of patients. The overall 30-day mortality was 6.1% (2 of 33) and that was unrelated to primary cardiac or cerebrovascular events.
Conclusions. Favorable outcome supports the justification for performing concomitant coronary artery bypass grafting with bilateral carotid endarterectomies in selected patients.
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Introduction
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Coexistence of symptomatic coronary artery disease and significant carotid artery stenosis ranges from 3.4% to 22% [1]. In the past two decades, the high-risk potential for neurologic dysfunction after coronary artery bypass grafting (CABG) in patients with concomitant carotid stenosis has been a real challenge for surgeons in terms of determining which operative sequence offers the highest freedom from cardiac or cerebral complications. In general, the incidence of postoperative stroke after CABG ranges from 0.7% to 5% [2, 3]. Coronary revascularization in a patient with internal carotid artery stenosis more than 50% is associated with a postoperative stroke rate of 6%, which increases significantly to more than 16% when stenosis is more than 90% [4–7]. To reduce the potential risk for postoperative stroke after CABG in patients with significant or symptomatic carotid artery stenosis, many surgeons have advocated combined CABG with unilateral carotid endarterectomy. However, clinical experience with the concomitant approach is conflicting [3, 5, 8]. Biases in patient selection criteria, variations in operative techniques, and intraoperative cerebral protective measures may help to explain a wide range of postoperative stroke rate (from 2% to 20%) associated with the combined approach.
Most of the prior studies on concomitant CABG with carotid endarterectomy (CEA) involved only one-sided (right or left) CEA. Occasionally, a small number of patients undergoing CABG present with symptomatic or significant bilateral carotid stenosis [8, 9]. Postoperative stroke rate after combined CABG with bilateral CEA has been 2.5 times higher than concomitant CABG and unilateral CEA [5, 8, 10]. This clearly emphasizes the need for developing reliable clinical guidelines for the management of patients with severe coronary and bilateral carotid artery stenosis. Therefore, the purpose of the study was to review our experience with combined CABG and bilateral CEA to establish patient outcome measures in justification of its performance.
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Patients and methods
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A retrospective nonrandomized chart review was performed in 33 patients who underwent simultaneous CABG and bilateral CEA at Albany Medical Center between January 1994 and December 1998. The study group consisted of unstable angina patients with bilateral carotid artery stenosis, more than 70% of whom were scheduled to undergo CABG. There were 14 men and 19 women (mean age, 68.6 years; range, 53 to 88 years; Tables 1 and 2).
Perioperative risk factors were hypertension (n = 28, 85%), obesity (n = 18, 55%), diabetes (n = 12, 36%), smoking history (n = 16, 48%), and prior peripheral vascular disease (n = 19, 58%). Three (9.1%) patients presented with a prior history of cerebral vascular disease, 2 (6.1%) had transient ischemic attacks, no patients presented with amaurosis fugax, and 1 patient (3.0%) had bilateral symptomatic carotid artery disease. This individual had a history of a right temporal infarct without residual deficit and a recent transient ischemic attack episode localized to the contralateral cerebral hemisphere. The majority of patients (30, 91%) had asymptomatic bilateral carotid artery disease. Right carotid artery stenosis of more than 70% was present in 31 patients (94%) and left carotid artery stenosis of more than 70% was present in 30 patients (91%) based on duplex ultrasound examination (Table 3).
Patient selection criteria
All patients scheduled for CABG had a bilateral carotid color-flow duplex ultrasound examination when they had history of transient ischemic attacks or any cerebral vascular accidents, or asymptomatic bruits on physical examination (Table 2). Our duplex criteria for determining internal carotid artery stenosis were patterned after criteria developed at the University of Washington [11]. The internal carotid artery peak systolic velocity, end-diastolic velocity, or ratios of internal-to-common carotid artery velocities were used to quantify the grade of stenosis. A recent internal review at our institution of patients evaluated from 1995 to present comparing color-flow duplex ultrasound results to angiographic findings and operative specimens has demonstrated a high level of accuracy between duplex criteria and percentage of stenosis determined at the time of operation. If a patient with neurologic symptoms scheduled for CABG had more than 70% stenosis by duplex ultrasound, a combined operation was entertained. All patients who had unilateral or bilateral asymptomatic hemodynamically significant carotid stenosis were further investigated with either magnetic resonant angiography or contrast angiography to confirm the validity of the ultrasound results. All patients with symptomatic carotid stenosis or bilateral lesions and more than 70% stenosis by duplex ultrasound and contrast angiography or magnetic resonant angiography were offered bilateral CEA at the same time as their coronary revascularization. Patients who underwent simultaneous unilateral CEA with CABG were excluded from the analysis. In addition, patients with bilateral carotid stenosis who underwent other open-heart operations without CABG were not included in the study. Two (6.1%) patients with unstable angina who underwent primary CABG, one had a mitral valve annuloplasty and the other had replacement of the aortic valve for aortic stenosis and were included in this analysis.
Operative techniques
Separate teams of cardiothoracic and vascular surgeons performed the combined CABG with bilateral CEA procedures. Additional exposure of both cervical regions to just above the earlobe was necessary for easier performance of CEA. No intraoperative cerebral monitoring devices were used in any of the 33 patients. While carotid endarterectomies were done, the cardiac surgical team harvested the saphenous vein conduit. Before either endarterectomy, exposure of both common carotid arteries and their bifurcations were performed through a vertical cervical incision anterior to the sternocleidomastoid muscle. Before clamping the carotid artery, 30 U/kg of intravenous heparin were given. The eversion carotid endarterectomy was routinely performed with an average carotid artery cross-clamp time of 14.7 ± 4.9 minutes (range, 9 to 21 minutes) on both sides. The side with greater stenosis was generally performed first. The neck incisions were closed with suction drains after the completion of the coronary revascularization. Since 1993 eversion endarterectomy of the internal carotid artery has been performed routinely at our institution as described previously without using any intraoperative shunt [12, 13].
The median sternotomy incision was used for CABG after completion of the bilateral carotid operations. The left internal thoracic artery was harvested routinely. Drifting in systemic temperature (30°C to 32°C) was allowed after initiation of cardiopulmonary bypass. A single aortic cross-clamp technique with cold blood cardioplegic arrest were primarily used. The average cross-clamp time was 123 ± 29 minutes (range, 77 to 183 minutes). Antegrade and retrograde warm cardioplegia (hot shot) was administered before removal of the aortic cross-clamp. The rest of the operation was completed in the usual standard fashion. The duration of the operation averaged 270 ± 25 minutes (range, 205 to 380 minutes).
Follow-up
During the immediate postoperative period, both vascular and cardiothoracic surgical teams monitored patients closely. In-hospital morbidity and mortality for each patient were documented. A neurology consult was obtained in all patients to better define any untoward cerebral events. Cardiac care was given in conjunction with a cardiologist. A major neurologic event was defined as recognition of a new motor or sensorial neurologic deficit and correlating symptoms with radiographic signs on computed tomographic scan or magnetic resonance imaging of the head. Data are presented in the text and tables as simple percentage and frequency distributions. As there were low frequencies of the expected outcomes, the Fisher’s exact test was used for statistical analysis. The results are reported as the mean ± standard error of the mean. Significant differences were considered to exist when calculated p values were less than 0.05.
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Results
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Concomitant CABG with bilateral CEA was performed urgently in 24 (73%) patients and electively in 9 (27%) patients. No bilateral carotid endarterectomies combined with coronary revascularization were carried out in emergency situations. Average carotid artery cross-clamp time was 14.7 ± 4.9 minutes (range, 9 to 21 minutes) and total perfusion time was 123 ± 29.2 minutes (range, 77 to 183 minutes). Mean number of coronary bypass grafts was 3.7 ± 0.98 per patient. Average length of stay in the cardiopulmonary intensive care unit was 4.2 ± 14.2 days (median, 1 day; range, 1 to 100 days), and total hospital stay was 16.2 ± 20.5 days. Postoperative in-hospital stay was 14.9 ± 20.3 days (median, 9 days; range, 5 to 118 days). Twenty-one (64%) patients were discharged before the tenth postoperative day. No permanent or transient neurologic events were observed in the early postoperative period. Nonfatal postoperative complications occurred in 27% (9 of 33) of patients (Table 4). Perioperative mortality occurred in 2 of 33 patients (6.1%). These 2 patients were identified as having mitral valve insufficiency associated with severely depressed left ventricular function (< 30%). One of them developed methicillin-resistant Staphylococcus aureus endocarditis of the native mitral valve 2 months after operation and eventually died of multiorgan system failure. Respiratory failure, gastrointestinal bleeding, and sepsis from methicillin-resistant Staphylococcus aureus pneumonia complicated this patient’s perioperative course. Another patient who had a combined CABG/CEA along with a posterior mitral annuloplasty suffered from low cardiac output syndrome postoperatively requiring prolonged use of an intraaortic balloon pump. Complications of respiratory failure, renal failure, and sepsis from infectious colitis eventually resulted in this patient’s death.
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Comment
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Routine carotid endarterectomy or coronary revascularization in patients without concomitant carotid and coronary disease or confounding illnesses can be performed with minimal morbidity and mortality [4, 14]. In patients with no carotid artery disease undergoing coronary revascularization, pooled data from 1985 to 1992 have demonstrated an early mortality rate of 2.7% and a stroke rate of 1.9% [14]. During the past decade cardiac mortality and associated morbidity have steadily declined; however, perioperative stroke rates have remained relatively constant. Faggioli and colleagues [4] demonstrated that CABG in the presence of unilateral hemodynamically significant carotid artery disease is associated with a 15% perioperative stroke risk. Hertzer and associates [15] reported that the incidence of permanent stroke was 6.7% if the contralateral internal carotid artery was more than 50% narrowed and 11% in the presence of contralateral internal carotid artery occlusion after CABG. The risk of stroke in CABG patients with bilateral hemodynamically significant carotid artery stenosis could be considerably higher. To reduce the neurologic morbidity in patients with concomitant carotid and coronary disease, many surgeons advocated CEA before or simultaneously with coronary revascularization. The rationale for this approach is based on the concern that the potential reduction in cerebral blood flow during cardiopulmonary bypass might be the antecedent factor for postoperative strokes. Furthermore, the effects of nonpulsatile flow and labile arterial pressure during cardiopulmonary bypass may also influence the incidence of neurologic events. Embolization of atheromatous material, air, fat, thrombus or thrombosis, or intracerebral hemorrhage are all potential factors in the genesis of strokes.
It is clear from previous and present data that the presence of bilateral or unilateral carotid artery occlusive disease is a risk factor for the development of neurologic injury after cardiac operations in the early and late perioperative periods [13, 14]. Most studies have identified that patients requiring coronary artery revascularization who have concomitant bilateral asymptomatic or symptomatic carotid disease are the most challenging group to manage. Several investigators have proposed that carotid endarterectomy should be performed on the side that contributes the majority of cerebral blood flow with or without cardiopulmonary bypass, and the contralateral side should be addressed at a later time in a reversed staged fashion [16]. Although Kouchoukos and colleagues [17] suggest the use of hypothermic circulatory arrest for cerebral protection during combined CABG and CEA in patients with bilateral carotid artery disease, we presume that the use of profound hypothermic circulatory arrest and prolonged hypothermic cardiopulmonary bypass is associated with an increased risk of neurologic injury. Cardiopulmonary bypass seems to be responsible for the stimulation of microemboli and the activation of multiple components of the inflammatory and complement cascade [18]. These events have been linked to neurologic injury and other morbidity associated with open-heart operations, and the extent of neurologic and systemic injury is directly proportional to the duration of cardiopulmonary bypass. Although, theoretically hypothermic circulatory arrest may offer some advantages, in most patients this method would significantly prolong the perfusion time. This inherent disadvantage predisposes the patients to an increased risk for cerebral hypoperfusion in addition to other detrimental effects of hypothermia and circulatory arrest.
To the best of our knowledge, so far, no study to date has been reported advocating the performance of simultaneous bilateral carotid endarterectomy and coronary revascularization. Most surgeons are reluctant to perform bilateral procedures in this setting because of the fear of increased neurologic, respiratory, and cardiac complications. In our opinion, performing a unilateral carotid endarterectomy while ignoring the contralateral diseased carotid in patients who have significant bilateral carotid stenosis may result in increased morbidity and mortality from the uncorrected lesion. Our rationale for performing bilateral endarterectomies in this setting has been based on historical and recent published data [3, 14, 19]. Nunn [19] reported a 58% stroke rate in untreated patients presenting with bilateral carotid stenosis. Hertzer and coworkers [14] reported that a significant number of patients in their series had developed contralateral strokes in the unoperated diseased carotid artery. A more recent report documented that the patients with bilateral carotid artery disease had a 23% incidence of stroke on the untreated contralateral side [3]. In an effort to reduce the risk of perioperative stroke for this patient population, at our institution we have advocated a simpler approach to patients with concomitant bilateral carotid artery stenosis and coronary artery disease. This report presents the analysis of our recent experience with 33 patients who underwent simultaneous bilateral carotid eversion endarterectomy immediately followed by coronary artery revascularization. The mortality of this series of 33 bilateral CEA/CABG operations was 6.1%. One death occurred in a patient whose postoperative course was complicated by poor left ventricular function, a multiresistant polymicrobial pneumonia, and mitral valve endocarditis resulting in sepsis and eventual death. The other mortality occurred in a patient with poor left ventricular function and severe mitral insufficiency who underwent a CABG and mitral valve annuloplasty. The patient’s death was directly related to the development of sepsis secondarily to Clostridium difficile toxic megacolon. Although these results are higher than the mortality for standard open-heart procedures, they are comparable to results reported in the literature for simultaneous unilateral carotid endarterectomy and coronary revascularization. No patient in this recent series suffered from a perioperative neurologic event. This compares favorably to our previously reported stroke incidence of 1.7% and 2.0% in 370 unilateral and 50 bilateral CEA/CABG and an overall operative mortality of 2.4% for procedures performed at our institution since 1980 [20]. Of note, patients with depressed left ventricular function (p = 0.002) and concomitant valvular pathology (p = 0.006) contributed to a higher mortality in patients undergoing bilateral CEA/CABG operations. On the contrary, the presence of bilateral symptomatic or asymptomatic carotid artery disease was not found to be a significant risk factor for increased neurologic events or mortality in our patient population.
In conclusion, patients presenting with significant coronary artery disease associated with symptomatic or asymptomatic bilateral carotid artery occlusive disease should be considered for simultaneous bilateral carotid endarterectomy and coronary revascularization. This combined operation can be performed with an acceptable overall mortality and morbidity. Patients with associated mitral valvular disease or moderate-to-severe left ventricular dysfunction are at higher risk for perioperative mortality. Nonetheless, severe left ventricular dysfunction or severe mitral valve disease is not the exclusion criterion for performing concomitant bilateral CEA/CABG.
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Acknowledgments
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We are grateful for the assistance of Kimberly O’Brien in the preparation of this manuscript.
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Footnotes
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This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/
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Abstract
Introduction
