Femoral Versus Aortic Cannulation for Surgery of Chronic Ascending Aortic Aneurysm Fitsum Lakew, MD, Piotr Pasek, MD, Michael Zacher, MD, Anno Diegeler, MD, and Paul P. Urbanski, MD Department of Cardiovascular Surgery, Cardiovascular Center Bad Neustadt, Bad Neustadt, Germany Background. Femoral artery cannulation and retrograde arterial perfusion have been postulated to increase the risk of cerebral embolism. In this study, the impact of the arterial cannulation site on the perioperative results after proximal aortic surgery is evaluated. Methods. Between January 1996 and December 2002, a total of 327 patients underwent proximal aortic repair for chronic non-dissected aortic disease. The arterial inflow was established by cannulation of the aortic arch (group A) or the femoral artery (group F) in 166 and 161 patients, respectively. Results. The early 30-day mortality was 0.9% (3 patients [1 patient in group A and 2 patients in group F]). The overall rate of early focal neurologic dysfunction (permanent and transient) was 4% (13 patients) and there was no significant difference between the two groups (4.2% vs 3.7%). Due to an intraoperative injury of the arterial wall, there were 6 repairs (3.6%) of the aortic arch in group A and 1 repair (0.6%) of the femoral artery in group F. The univariable examination of preoperative and intraoperative variables demonstrated that hypertension and increased cholesterol level could be possible independent risk factors for neurologic morbidity. In the following stepwise logistic regression, only the preoperative hypercholesterolemia was identified as an independent predictor for postoperative focal neurologic dysfunction. Conclusions. The arterial inflow via the femoral artery and the subsequent retrograde perfusion during cardiopulmonary bypass do not increase the risk of neurologic complications in patients who undergo proximal aortic repair due to chronic non-dissected aortic aneurysm. Because there is an increased risk of aortic wall injury during cannulation, the femoral artery seems to be more suitable in these cases for cannulation than the proximal aorta. (Ann Thorac Surg 2005;80:84 9) 2005 by The Society of Thoracic Surgeons Cerebrovascular injury is a major source of morbidity and mortality after cardiac surgery, especially after surgery of the proximal aorta. Possible causes for this neurologic complication, such as global ischemia, malperfusion, and cerebral embolism are currently being discussed [1 5]. The attempt to avoid cerebral embolism has directed the attention of cardiac surgeons toward the cannulation site. It is postulated that femoral cannulation is associated with an increase of neurologic events. The presumed mechanism of injury is the period of retrograde perfusion from the femoral artery through a diseased aorta mobilizing atheromatous debris into the bloodstream and occluding cerebral microcirculation. To establish antegrade perfusion, other arterial cannulation sites have been favored [1 4]. To determine whether cannulation of the femoral artery and retrograde perfusion during surgery of the proximal aorta for chronic aneurysm is responsible for an increase of neurologic morbidity, we have retrospectively analyzed 327 patients, of whom approximately half had cannulation of the femoral artery. Accepted for publication Feb 1, 2005. Address reprint requests to Dr Urbanski, Herz- und Gefaess-Klinik, Salzburger Leite 1, Bad Neustadt, 97616 Germany; e-mail: p.urbanski@ herzchirurgie.de. Patients and Methods From January 1996 to December 2000, a total of 327 patients underwent replacement of the ascending aorta for chronic non-dissected aneurysm at our institution. The study population included 227 men and 100 women with a mean age of 61 years (range, 25 to 84 years). All operations were performed by only four consultant surgeons, although 277 patients (85%) were operated on by the senior author (PPU). In all cases, the arterial return for cardiopulmonary bypass was achieved by cannulation of either the distal ascending aorta, alternatively aortic arch (group A, 166 patients) or the femoral artery (group F, 161 patients). The only criteria for choosing the cannulation site were the distal extension of the aneurysm and the atheromatous alteration or calcification within this region. The decision was made on the basis of the computed tomographic imaging and on the intraoperative visual or palpatory evaluation. Neither the presence of a peripheral vascular disease nor the pathology of thoracoabdominal aorta were taken into consideration for the choice of the cannulation site. Intraoperative findings in 3 patients in group F disclosed that the initially prepared femoral artery was not suitable for cannulation so that dissection and cannulation of the contralateral femoral artery was necessary. In another patient, placement of a 2005 by The Society of Thoracic Surgeons 0003-4975/05/$30.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2005.02.006
Ann Thorac Surg LAKEW ET AL 2005;80:84 9 ASCENDING AORTIC ANEURYSM Table 1. Preoperative Patient Characteristics Total 327 A a 166 F a 161 Male gender 227 (69.4) 119 (71.7) 108 (67.1) Age (y) 60.5 12.7 60.5 12.6 60.5 12.7 New York Heart Association functional class III/IV 165 (50.5) 86 (51.8) 79 (49.1) Urgent or emergency procedure 51 (15.6) 23 (13.8) 28 (17.4) Concomitant disease Hypertension 198 (60.6) 99 (59.6) 99 (61.5) Coronary heart disease b 64 (19.6) 41 (24.7) 23 (14.3) Diabetes 26 (8.0) 11 (6.6) 15 (9.3) Chronic obstructive pulmonary disease 25 (7.6) 14 (8.4) 11 (6.8) Peripheral vascular disease 15 (4.6) 9 (5.4) 6 (3.7) Distal aortic aneurysm c 15 (4.6) 5 (3.0) 10 (6.2) Previous neurologic events 10 (3.1) 5 (3.0) 5 (3.1) Previous surgery Aortic valve 20 (6.1) 8 (4.8) 12 (7.5) Valved graft 1 (0.3) 0 1 (0.6) Coronary artery bypass grafting 6 (1.8) 4 (2.4) 2 (1.2) Mitral valve 4 (1.2) 3 (1.8) 1 (0.6) 85 CARDIOVASCULAR a No significant differences between the groups were noted unless otherwise indicated; b p value 0.018; c thoracic or abdominal aorta with a diameter equal or more than 4 cm. cannula of sufficient size was not possible on both sides due to severe arteriosclerosis of the iliac arteries. In this case, arterial return was achieved by cannulation of both femoral arteries with smaller cannulas and connecting these with a y-shaped tube. Pathologic alteration of the thoracoabdominal aorta also did not influence the decision making in regard to the cannulation site. Obviously, in patients with abdominal or thoracoabdominal aneurysm, an extensive pathology of the proximal aorta was more common so that these patients had to be cannulated mostly through the femoral artery. Detailed preoperative data are listed in Table 1. All operations were performed through a median sternotomy. The cannulation site for the arterial return was Table 2. Aortic and Aortic Valve Pathology Total A a F a Aneurysm cause Miscellaneous 154 (47.1) 80 (48.2) 74 (45.9) Atherosclerotic 30 (9.2) 17 (10.2) 13 (8.2) Degenerative 143 (43.7) 69 (41.6) 74 (45.9) Marfanoid 28 (8.6) 15 (9.0) 13 (8.1) Aortic valve lesion Pure or predominant 83 (25.4) 30 (18.1) 53 (32.9) stenosis Pure or predominant 144 (44.0) 82 (49.4) 62 (38.5) insufficiency Stenosis and insufficiency 65 (19.9) 37 (22.3) 28 (17.4) equal Artificial valve 21 (6.4) 8 (4.8) 13 (8.1) No pathology 14 (4.3) 9 (5.4) 5 (3.1) a No significant differences between the groups were noted. chosen as previously described after opening of the pericardium. Myocardial protection was instituted with antegrade cold crystalloid cardioplegia. In cases where circulatory arrest for distal aortic repair was necessary, brain protection with deep hypothermia was completed pharmacologically with thiopental and cortisone in addition to topical cooling of the head. Neither a retrograde nor a selective antegrade cerebral perfusion was used. There was no difference between the groups concerning the cause of the aortic aneurysm as well as the frequency of the aortic valve disease requiring an operation and their pathology (Table 2). The ascending aorta was replaced in all cases, mostly using a valved composite graft. The most frequent con- Table 3. Extent of Aortic Replacement and Concomitant Procedures Total A a F Ascending aortic replacement Valved conduit 264 (80.7) 126 (75.9) 138 (85.7) Supra-coronary valve 33 (10.1) 21 (12.7) 12 (7.5) replacement Valve-sparing procedure 14 (4.3) 12 (7.2) 2 (1.2) Supra-coronary 16 (4.9) 7 (4.2) 9 (5.6) Coronary artery bypass 57 (17.4) 38 (22.9) 19 (11.8) grafting b Complete arch replacement c 27 (8.3) 5 (3.0) 22 (13.7) Mitral valve repair 16 (4.9) 7 (4.2) 9 (5.6) a No significant differences between the groups were noted unless otherwise indicated; b p-value 0.008; c p value 0.001.
86 LAKEW ET AL Ann Thorac Surg ASCENDING AORTIC ANEURYSM 2005;80:84 9 Table 4. Operative Data Total A F p value Cardiopulmonary bypass duration (min) 146.1 44.8 136.4 47.6 156.1 39.4 p 0.0001 Aortic cross-clamp time (min) a 85.5 28.3 80.1 29.3 91.1 26.1 p 0.0001 Circulatory arrest procedures 91 (27.8.%) 19 (11.4%) 72 (44.7%) p 0.0001 Circulatory arrest time 16.0 9.6 16.1 8.3 16.0 10.0 NS Lowest rectal temp ( C) With circulatory arrest 21.5 1.9 21.5 2.1 21.5 1.9 NS Without circulatory arrest 26.7 2.6 27.1 2.1 25.9 3.3 NS a Including circulatory arrest. NS not significant. comitant procedure in the whole study population was coronary artery bypass grafting followed by complete arch replacement. Whereas coronary artery bypass grafting was significantly more frequent in group A, arch replacement was performed significantly more often in group F (Table 3). The first difference resulted from the fact that more patients with circumscribed proximal aortic aneurysm also had coronary artery disease (24.7% of group A vs 14.3% of group F; p 0.018), whereas more patients with distal extension of the proximal aneurysm seemed to also have aneurysmal changes of the abdominal or thoraco-abdominal aorta (3.0% of group A vs 6.2% of group F; p not significant). The higher incidence of complete arch replacement as well as procedures with circulatory arrest in the group with femoral cannulation (group F) were consequently brought about by the distal extent of the aortic aneurysm. After this the cardiopulmonary bypass time as well as the aortic cross-clamp time were longer in group F. Nevertheless, average circulatory arrest duration was not different in both groups. The detailed operative data are shown in Table 4. Values in the tables and text are expressed as a mean standard deviation unless otherwise indicated. All statistical analyses were performed using SPSS software (SPSS Inc, Chicago, IL). The continuous variables were analyzed by using the t test or Mann-Whitney s U test, and the categorical variables were tested by the 2 test or Fischer s exact test when appropriate. All preoperative and intraoperative variables were first analyzed by using univariable analysis to determinate factors that influence the focal neurologic morbidity. The variables that achieved a p value of less than 0.1 in the univariable analysis were examined using multivariable analysis with a forward stepwise logistic regression model to evaluate independent risk factors for focal (permanent and transient) neurologic dysfunction. A permanent neurologic dysfunction was defined as a focal neurologic symptom with positive computed tomographic findings and residual neurologic symptoms upon discharge. A transient neurologic dysfunction was defined as focal symptoms with a negative computed tomography and complete regression of symptoms prior to discharge. Results There were 3 deaths (0.9%) within 30 days after surgery. One patient in group A died on postoperative day 5 from a hemorrhagic shock after a rupture of the porcine root prosthesis at the suture line to the ascending aortic vascular tube. The second patient (group F) died on postoperative day 6 due to a respiratory failure caused by bleeding into the bronchial system. The third patient (group F) died on postoperative day 5 from a low cardiac output, subsequent to a perioperative myocardial infarction. During the postoperative in-hospital stay, but after the 30-day time range, another patient of group A died from sepsis and multiple organ failure. A total of 13 patients (4%) suffered from a perioperative focal neurologic dysfunction. Permanent and transient neurologic events were observed in 2.4% and 1.8% in group A as well as 3.1% and 0.6% in group F, respectively. Univariable analysis of all relevant preoperative and intraoperative variables revealed hypertension and increased cholesterol level to be possible predictors of focal neurological dysfunction. In the following stepwise logis- Table 5. Early Mortality and Morbidity Total A a F a 30-day mortality 3 (0.9) 1 (0.6) 2 (1.2) In-hospital mortality 4 (1.2) 2 (1.2) 2 (1.2) Rethoracotomy 17 (5.2) 9 (5.4) 8 (5.0) Low cardiac output 13 (4.0) 7 (4.2) 6 (3.7) Myocardial infarction 1 (0.3) 0 1 (0.6) Pericardial effusion 27 (8.3) 13 (7.8) 14 (8.7) Respiratory failure b 4 (1.2) 1 (0.6) 3 (1.9) Permanent pacemaker c 36 (11.0) 14 (8.4) 22 (13.7) Neurologic deficit 13 (4.0) 7 (4.2) 6 (3.7) Permanent 9 (2.8) 4 (2.4) 5 (3.1) Transient 4 (1.2) 3 (1.8) 1 (0.6) Onset 24 h after surgery 5 (1.5) 2 (1.2) 3 (1.7) Onset 24 h after surgery 8 (2.4) 5 (3.0) 3 (1.7) a No significant difference between the groups were noted; b required tracheotomy; c in a total of 25 patients (12 in group 1, 13 in group 2, respectively) there were already preoperative indications for pacemaker implantation because of atrioventricular block.
Ann Thorac Surg LAKEW ET AL 2005;80:84 9 ASCENDING AORTIC ANEURYSM tic regression analysis, only the preoperative hypercholesterolemia (relative risk, 1.015; 95% confidence interval, 1.001 to 1.030) was identified as an independent predictor for the postoperative neurologic dysfunction. Furthermore, there was a distinct tendency of injury to the aortic wall during cannulation. While cannulating the distal ascending aorta or the aortic arch in 6 patients (3.6%) of group A, the aortic wall was injured, which made an extension of the operation necessary, including circulatory arrest. In contrast, in group F the femoral artery was injured in only 1 patient during cannulation and needed to be replaced with a vascular prosthesis. All relevant early postoperative complications are listed in Table 5. Comment There is an ongoing controversial discussion of whether retrograde perfusion through the femoral artery poses a higher neurologic risk in aortic surgery compared with other cannulation sites. Analyzing existing studies that report different cannulation techniques is difficult because the patient populations described usually include not only chronic aortic aneurysms but acute aortic dissections as well. This can impair the results and consequently the conclusions, because the choice of the cannulation site in cases of aortic dissection is of utmost importance for sufficient perfusion during cardiopulmonary bypass and subsequently for perioperative neurologic results. Cannulation in aortic dissection should always be diligently chosen on a case-by-case basis depending on several factors (eg, extent of the dissection, impairment of the true lumen, and localization of entry). However, routine cannulation of the arch vessels, such as the axillary artery can be beneficial in acute aortic dissection, if only for the reason of antegrade perfusion of the true lumen [4]. But it remains questionable whether routine cannulation of the supra-aortic vessels is necessary in non-dissected aortic diseases. Some authors recommend routine cannulation of the arch vessels, because on one hand, the ascending aorta is a main source of emboli, and on the other hand, it is postulated that cannulation of the femoral artery and retrograde perfusion can be complicated by a higher incidence of neurologic events in chronic aneurysm [1 3, 6]. To investigate the impact of aortic and femoral cannulation on neurologic morbidity we conducted a retrospective study in which we analyzed all patients who were operated on at our institution during a 7-year time period for chronic aneurysm of the proximal thoracic aorta. Patients with acute or chronic aortic dissection were excluded. In this relatively homogeneous patient group, the incidence of permanent neurologic event was 2.8%. In comparison, the rate for permanent neurologic deficit in two of the most recent publications presenting the biggest patient cohorts with routine cannulation of the axillary artery was 5% [2] and 4.6% [3]. However, included in these groups are patients with chronic aneurysm as well as acute aortic dissection. In the series from Okita and colleagues [7], 148 patients with 45 cannulations of the ascending aorta and 103 cannulations of the femoral artery were analyzed in which half of the patients had an acute aortic dissection. The global incidence of neurologic events was 4%. In the multivariate analysis, aortic cannulation was identified as an independent predictor for mortality, whereas femoral cannulation was neither a risk factor for mortality nor for neurologic morbidity. Westaby and colleagues [5] compared the results after cannulation of the aorta in a retrospective study, and the femoral artery in 61 patients undergoing surgery of the aortic arch and descending aorta. Unfortunately, the patient groups were operated on in different time periods and included patients with chronic aneurysm as well as acute dissection. Moreover, this patient cohort was very specific due to the high percentage of patients with thoracoabdominal aneurysm. On the other hand, the same author group analyzed a series of 29 patients with chronic atheromatous aneurysm of the ascending aorta and the aortic arch without involvement of the descending aorta, either with cannulation of the femoral artery or the aorta, documenting very good neurologic results without permanent focal neurologic dysfunction [8]. This was confirmed in our series containing more than 10 times the number of patients in which the risk for all (permanent or transient) early postoperative 30-day focal neurologic deficits was 4%. Among these patients who suffered from cerebrovascular injury, only 1 had a thoracoabdominal aneurysm. This patient was cannulated through the femoral artery. In our opinion it was not relevant, because Kouchoukos and colleagues [9] documented 192 patients with thoracoabdominal aneurysm of all patients who were cannulated by femoral artery in their series, and despite retrograde perfusion the risk of stroke was only 2%. All relevant preoperative and intraoperative variables were examined statistically, and in the multivariate analysis neither the femoral nor the aortic cannulation was identified as a risk factor. The only independent predictor for neurologic morbidity was preoperative hypercholesterolemia, regardless of the cannulation site. This is not remarkable, because a correlation between cholesterol and embolic events during cardiopulmonary bypass was recognized 3 decades ago [10]. Nevertheless, during cannulation of the aorta with pathologic changes in the wall, there is a higher risk of injury to the aortic wall, necessitating an expansion of the operation. In our series, there was a tendency of cannulation-related injury to the aortic wall as compared with the femoral artery (6 cases vs 1 case; p not significant), although the small number does not have a statistical impact. However, the consequences of these injuries cannot be compared. An extension of the operation on the aortic arch, including arch or hemi-arch replacement, increases the operative risk substantially in comparison with a vascular interposition on the femoral artery. Furthermore, it is noteworthy that in our study, neither the use of circulatory arrest nor its duration were identified as risk factors. This stands in contradiction to Czerny and colleagues [11] who reported in 2003 on a 87 CARDIOVASCULAR
88 LAKEW ET AL Ann Thorac Surg ASCENDING AORTIC ANEURYSM 2005;80:84 9 series of 369 patients with ascending aorta and aortic arch replacement that the use of deep hypothermic circulatory arrest was the only independent predictor for permanent neurologic deficit. Even though the circulatory arrest time from the Czerny group was double the length compared with ours (32 min vs 16 min), we do not presume that this is the only explanation for the different results. In his group, the percentage with acute aortic dissection was 47%, and deep hypothermic circulatory arrest was performed in 54.7% of the patients. The univariate analysis, on the other hand, has revealed that acute aortic dissection, in which circulatory arrest was presumably more frequently used, was a risk factor for permanent neurologic injury. This leads us to emphasize again that in regard to the cannulation and perfusion, chronic aneurysm and acute dissection have to be evaluated separately. Even though circulatory arrest of short duration was not identified as a risk factor for neurologic events in our series, we do believe that in cases of extended operation on the aortic arch, an alternative cannulation of the arch vessels can be beneficial. However, within the time frame of the study of patients with chronic non-dissected aneurysms, we did not utilize supra-aortic vessels for arterial return. Recently, our past experience with the cannulation technique of the common carotid artery for patients with acute aortic dissection encouraged us to introduce this technique, even for patients with chronic aneurysms when circulatory arrest for distal repair is necessary. In our opinion, the most important advantage of arch arteries cannulation techniques lies in the simple feasibility of selective cerebral perfusion through the arterial line in abandonment of deep hypothermia during extensive surgery on the aortic arch [1 4, 12, 13]. In conclusion, cannulation of the femoral artery in patients with chronic non-dissected diseases of the proximal aorta can be considered as a standard for arterial return. It is quick and easy to perform and does not increase the risk of neurologic events. Patients requiring an operation of the ascending aorta without distal extension can be cannulated in the aortic arch with special caution; keeping in mind the increased risk of injury. Due to improved protection of the brain, particularly in extended operations on the aortic arch, an alternative cannulation technique of the arch vessels, such as axillary or carotid arteries can be considered. The authors thank Alexandra Metz for preparing this article and Melissa Lindner for reviewing it. References 1. Sabik JF, Lytle BW, McCarthy PM, Cosgrove DM. Axillary artery: an alternative site of arterial cannulation for patients with extensive aortic and peripheral vascular disease. J Thorac Cardiovasc Surg 1995;109:885 91. 2. Sabik JF, Nemeh H, Lytle BW, et al. Cannulation of the axillary artery with a side graft reduces morbidity. Ann Thorac Surg 2004;77:1315 20. 3. Strauch JT, Spielvogel D, Lauten A, et al. Axillary artery cannulation: routine use in ascending aorta and aortic arch replacement. Ann Thorac Surg 2004;78:103 8. 4. Reuthebuch O, Schurr U, Hellermann J, et al. Advantages of subclavian artery perfusion for repair of acute type A dissection. Eur J Cardio-thorac Surg 2004;26:592 8. 5. Westaby S, Katsumata T, Vaccari G. Arch and descending aortic aneurysms: influence of perfusion technique on neurological outcome. Eur J Cardio-thorac Surg 1999;15:180 5. 6. Blauth CI, Cosgrove DM, Webb BW, et al. Atheroembolism from the ascending aorta. J Thorac Cardiovasc Surg 1192;103: 1104-12. 7. Okita Y, Takamoto S, Ando M, Morota T, Matsukawa R, Kawashima Y. Surgery for acquired heart disease. J Thorac Cardiovasc Surg 1998;115:129 38. 8. Westaby S, Saito S, Anastasiadis K, Moorjani N, Jin XY. Aortic root remodeling in atheromatous aneurysms: the role of selected sinus repair. Eur J Cardio-thorac Surg 2002;21: 459 64. 9. Kouchoukos NT, Masetti P, Rokkas CK, Murphy SF. Hypothermic cardiopulmonary bypass and circulatory arrest for operations on the descending thoracic and thoracoabdominal aorta. Ann Thorac Surg 2002;74:S1885 7. 10. Price DL, Harris J. Cholesterol emboli in cerebral arteries as a complication of retrograde aortic perfusion during cardiac surgery. Neurology 1970;20:1209 14. 11. Czerny M, Fleck T, Zimpfer D, et al. Risk factors of mortality and permanent neurologic injury in patients undergoing ascending aortic and arch repair. J Thorac Cardiovasc Surg 2003;126:1296 301. 12. Kouchoukos NT, Masetti P. Total aortic arch replacement with a branched graft and limited circulatory arrest of the brain. J Thorax Cardiovasc Surg 2004;128: 233 7. 13. Urbanski PP. Cannulation of the left common carotid artery for proximal aortic repair. J Thorac Cardiovasc Surg 2003; 126:887 8. INVITED COMMENTARY In recent years, axillary artery cannulation has gained considerable popularity as a site for arterial perfusion for thoracic aortic surgery, almost to the point of attaching a negative stigma to the use of the femoral artery for this purpose. There is no question that axillary artery cannulation offers significant advantages in specific circumstances, especially when the thoracoabdominal aorta is heavily diseased with mobile atheromatous lesions. In such circumstances, axillary cannulation can avoid the lifting of the aortic tree bark that can occur with retrograde femoral perfusion. This article by Lakew and colleagues serves an important role by reminding us that traditional femoral artery cannulation remains an excellent option for many patients. The authors have wisely restricted their analysis to a well-defined and specific group (ie, those patients undergoing surgery only for chronic aortic aneurysm, not dissection). This specificity permits meaningful results by defining a relatively uniform clinical setting for analysis. Also the number of patients is large and the two techniques (ie, femoral and direct aortic cannulation) are carried out simultaneously during the study period, an 2005 by The Society of Thoracic Surgeons 0003-4975/05/$30.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2005.03.118