Asian Cardiovasc Thorac Ann 2006;14:14-19
© 2006 Asia Publishing EXchange Ltd
Ascending Aorta or Arch Surgery: Is Previous Cardiac Surgery a Risk Factor?
Pradeep Narayan, FRCS,
Chris A Rogers, PhD,
Massimo Caputo, MD,
Gianni D Angelini, FRCS,
Alan J Bryan, FRCS
Bristol Heart Institute, Bristol Royal Infirmary, Bristol, United Kingdom
For reprint information contact: Alan J Bryan, FRCS Tel: 44 11 7928 5151 Fax: 44 11 7928 5192 Email: Alan.Bryan{at}ubht.swest.nhs.uk, Department of Cardio-thoracic Surgery, Bristol Royal Infirmary, Bristol BS2 8HW, United Kingdom.
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ABSTRACT
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Surgery on the ascending aorta ± arch is a challenge. The risks involved in such operations after previous cardiac surgery were assessed in elective and emergency settings in a single institution. Over a 10-year period, 29 patients underwent replacement of the ascending aorta ± arch following previous cardiac surgery. In 12 patients (41.4%), the procedure was carried out on an emergency basis. Thirteen had previous replacement of the ascending aorta and 16 had previous valve replacement with or without coronary artery bypass; 4 patients were undergoing a 3rd cardiac operation. Concomitant procedures included coronary artery bypass in 2, arch replacement in 4, and descending aortic replacement in one. The overall in-hospital mortality was 13.8% (4/29) vs. 12.4% (33/267) in primary procedures. Mortality in elective repeat surgery was 5.9% (1/17) vs. 25% (3/12) in emergency re-operations. The incidences of permanent stroke (3.4%) and renal failure (3.4%) were similar to first-time operations. Elective re-operation for ascending aorta ± arch repair can be accomplished with acceptable mortality and morbidity. Outcomes in emergency cases carry a higher early mortality but still conform to contemporary expectations and are similar to emergency first-time aortic surgery.
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INTRODUCTION
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Surgery on the ascending aorta ± arch following previous cardiac surgery is a technically complex procedure that is becoming increasingly common. Longer survival after the primary procedure, an ageing population, and improved knowledge and expertise in the management of repeat cardiac surgery have all contributed to an increased willingness on the part of surgeons to undertake operations on the ascending aorta ± arch following previous cardiac surgery. Paraprosthetic leak and aneurysmal dilatation of the ascending aorta following previous aortic valve replacement (AVR), infection in the prosthetic valve or aortic graft, and degeneration of biological conduits or homografts are some of the more common indications for repeat surgery. Valve-sparing operations in the primary aortic procedure have also increased the population of patients who may be at risk of re-operation.1 Long-term follow-up and improved diagnostic aids (computed tomography and magnetic resonance imaging) may enable identification of complications after aortic surgery in a relatively asymptomatic patient. Based on experience with redo coronary artery bypass grafting (CABG), one may speculate that surgery of the ascending aorta/aortic arch following previous cardiac surgery would carry a higher early mortality and significantly worse morbidity than first-time procedures.2 To assess the early mortality, morbidity, and midterm survival in such patients, we analyzed data collected prospectively over the last 10 years at our center. We also compared the risks of re-operation with first-time surgery performed during this period, in elective and emergency settings.
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PATIENTS AND METHODS
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A consecutive series of patients undergoing surgery on the ascending aorta ± arch over a 10-year period were identified. They were grouped according to whether they had a primary or repeat procedure. Those in whom the previous cardiac surgery was carried out through a thoracotomy incision were excluded, and patients undergoing redo surgery on the descending aorta/aortic arch through a thoracotomy incision were also excluded. The indications for repeat aortic surgery included aneurysm formation, aortic dissection, valvular incompetence with aneurysm formation, and infection of the aortic prosthesis or graft. Demographics, pre-, peri- and postoperative data for procedures prior to April 1996 were extracted from the operation notes. Thereafter, data were collected prospectively on all patients undergoing cardiac surgery, and entered into a database (Patient Analysis and Tracking System). Deaths before hospital discharge were identified from mortality data provided by the National Health Service Strategic Tracing Service (NSTS). All patients were successfully matched to the NSTS database. Definitions of operative priority, pre-morbid conditions, and postoperative complications were those used in the National Adult Cardiac Database and accepted by the Society of Cardio-thoracic Surgeons of Great Britain and Ireland (available at: www.scts.org).
Over the 10-year period, a range of surgical techniques was practiced; nevertheless, there was broad consensus on the operative strategy, perfusion techniques, neuroprotective and blood conservation strategies. All operations were performed through a median sternotomy incision. Where the aorta was eroding or closely applied to the sternum, cardiopulmonary bypass (CPB) with profound cooling to 18°C was instituted prior to sternotomy, and the left ventricle was vented via a small left anterior thoracotomy. Cardiopulmonary bypass was established through cannulation of the common femoral artery, and venous drainage was provided by a two-stage cannula, but where retrograde cerebral perfusion was used or planned, bicaval cannulation was used. Cerebral protection was achieved, depending on the era of surgery, by profound hypothermia with or without retrograde or antegrade cerebral perfusion.3 Fentanyl 20–35 µg·kg–1 and pancuronium 0.15 µg·kg–1 were used in all cases, along with isoflurane or propofol before CPB. Propofol 3 mg·kg–1·h–1 infusion was given routinely during CPB. Where deep hypothermic circulatory arrest was required, either propofol 3 mg·kg–1·h–1 infusion or thiopentone 25–30 mg·kg–1 was used, depending on individual preference. Recently, transesophageal echocardiography is being used routinely intraoperatively. The application of ice packs for cerebral protection during deep-hypothermic circulatory arrest again depended on individual preference.
Baseline and operative characteristics were compared using the chi-squared or Fisher’s exact test (categorical variables) or the Wilcoxon rank sum test (continuous variables). As the number of adverse outcomes after surgery was few, particularly in the redo group, the results were compared without adjustment for baseline and operative characteristics. Binary variables were compared using Fisher’s exact test, and continuous variables were compared using the Wilcoxon rank sum test (intensive care unit stay) or the log rank test (hospital stay and postoperative survival to 3 years). Three-year postoperative survival after primary and redo procedures was compared between patients who had elective surgery and those needing an emergency operation. This analysis was adjusted for baseline and operative characteristics: age, sex, Parsonnet score, Marfan syndrome, endocarditis, associated procedures, CPB duration, circulatory arrest > 45 min, arch replacement, technical difficulty (interposition graft with valve re-suspended), and era of surgery. Age, Parsonnet score and CPB duration were grouped into categories and then fitted as a continuous score. Cox proportional hazards regression was used, and the validity of the proportionality assumption was checked. Surviving patients were checked 2 months prior to the NSTS download (95% of deaths are logged with NSTS within 2 months) or at re-operation. All analyses were carried out using Stata software (Stata Corp., College Station, TX, USA).
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RESULTS
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Of 296 eligible patients identified, 267 underwent first-time procedures and 29 had repeat procedures after a previous median sternotomy. Thirteen had previous replacement of the ascending aorta and 16 had previous valve replacement with or without coronary artery bypass. Four patients were undergoing a 3rd cardiac operation. Seven surgeons carried out the operations. One is a high-volume operator with a specialist interest in surgery of the ascending aorta ± arch; 14 of the 29 redo procedures (48%) were carried out by this surgeon.3 The number of procedures on the ascending aorta ± arch after previous cardiac surgery has increased over time from 4 in the first 3 years of the study period to 16 in the last 3 years. The interval between the repeat operation and previous surgery ranged from 1 month to 10 years.
Baseline characteristics were broadly similar across the 2 groups (Table 1
). The only significant differences were in age distribution, Parsonnet scores, and the percentage of patients with endocarditis. The difference in Parsonnet scores was to be expected as redo procedures carry a score of 5 for first time redo and 10 if the operation is being repeated for a second time. Surgical procedures and operative details are summarized in Table 2. Similar percentages of patients had arch replacements, composite root replacements, and interposition grafts in the 2 groups. Fewer redo patients had associated procedures. The CPB times were significantly longer for redo procedures, but the 2 groups had similar crossclamp and circulatory arrest times. Aortic valve replacement was performed in 14 redo patients, of whom 5 had previous CABG, with 2 of these having combined AVR and CABG. In the study population as a whole (n = 296), there were 37 in-hospital deaths (12.5%); 4 of these were in the redo group (Table 3). There were 3 deaths among the 12 emergency patients (mortality rate, 25%). All in-hospital outcomes examined were similar in the two groups: mortality, re-operation for bleeding, major sternotomy wound complications, neurological and renal complications, and length of intensive care unit and postoperative stay. The median follow-up of survivors was 3 years in the primary procedure group, and 2 years in the redo group. There were 60 deaths in total over the 3 years, 50% occurred within 11 days of surgery. There was no significant difference in 3-year survival between the 2 groups (log rank test: p = 0.55). Examining the impact of surgical priority (Table 4), after adjustment for baseline and operative characteristics, it was revealed that an emergency procedure carried a mortality risk almost 4 times that of an elective procedure (hazard ratio 3.92, 95%CI 1.96 to 7.83, p < 0.001; Figure 1), but there was no significant difference in the risk of death for first-time and redo operations (hazard ratio 1.11, 95%CI 0.45 to 2.70, p = 0.82). The difference in survival between emergency and elective procedures was seen in both first-time and redo procedures; there was no evidence to suggest a difference in the effect of surgical priority between the primary and redo groups (p = 0.44).
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DISCUSSION
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Repeat CABG and valve replacement have been reported to carry a higher mortality than primary procedures.2,4 Repeat median sternotomy itself carries an additional mortality rate, with a 6–10% incidence of re-entry accidents.5 Hence, one might expect that surgery on the ascending aorta ± arch following previous cardiac surgery would carry a much higher mortality and morbidity than first-time aortic operations. Mortality rates of 6–22% have been reported for ascending aortic operations following previous cardiac surgery.6–7 These mortality rates are not dissimilar to those for primary ascending aortic surgery and suggest that with appropriate precautions, increasing experience, and development of expertise it is possible to perform repeat ascending aortic procedures with acceptable rates of mortality and postoperative morbidity.8–9 This is supported by the mortality data from our study (13.8% in the redo group vs. 12.5% in the primary procedure group). In fact, mortality in the elective re-operation group in our unit was only 5.8%. No deaths occurred in the subgroup where the re-operation involved only replacement of the ascending aorta as an elective procedure, over the entire study period. The overall mortality of 13.8% compares favorably with the available data from some of the high-volume specialist centers, and further reinforces the view that surgery on the ascending aorta ± arch following previous cardiac surgery can be carried out at most centers without adding to the risk of early mortality and morbidity.1,6–7
Our study showed that emergency re-operations carried a higher mortality (25%), which was in line with mortality rates of 19–25% reported by some of the leading groups for primary emergency surgery of the ascending aorta ± arch.8,10 It is accepted that emergency ascending aortic procedures carry a significantly higher mortality than elective procedures. Bachet and colleagues7 have shown that emergency operations on the proximal thoracic aorta carry a 10-fold increase in operative risk. Our data supports this finding in that emergency procedures carried a mortality risk almost 4 times that of elective procedures, and there was no significant difference between the risk of death for first-time and redo operations. Thus, it is the emergency nature of the procedure, rather than re-operation itself, that contributes to poorer outcome.
In agreement with other reports, AVR was the most common operation associated with repeat surgery on the ascending aorta ± arch in our study (14/29).11 While the overall incidence of acute dissection after AVR was reported to be 0.6%, the incidence of acute dissection among patients with significant aortic dilatation at the time of AVR was 27%.11 To reduce the probability of needing a re-operation, current thinking indicates replacement of the ascending aorta if the diameter is > 5 cm at the time of AVR.12 Coronary artery bypass grafting has also been found to be the primary procedure in a significant number of re-operations on the ascending aorta ± arch. This is either due to less aggressive management of a dilated, diseased, or aneurysmal aorta at the time of the initial procedure, or to the development of dissection following the procedure. Dissections following CABG can present intraoperatively or after many years.13 The time of presentation of dissection following previous CABG ranged from 1 month to 10 years in our study. Valve-sparing procedures in acute dissections, while being certainly beneficial in appropriate cases, may expose the patient to an increased risk of re-operation, especially in cases of Marfan syndrome or annular ectasia.14–15 Patients with acute type A aortic dissection who have severe aortic valve insufficiency are thought to be at increased risk of proximal re-operation, and a more aggressive proximal repair at the initial operation has been recommended.16 While there is general agreement that the distal resection should be extended to include the tear, it is not always possible to obliterate the false channel in its entirety, and a more distal extent of the false channel is thought to be a significant risk factor for re-operation on the distal aorta.17 Extended total arch replacement for acute type A aortic dissection has been advocated by some to reduce the risk of re-operation on the distal aorta, but no definite benefits have been demonstrated by others.17–19 In fact, it has been suggested that it might even add to the already high operative risk.16
Midterm survival at 3 years for the redo surgery group was very similar to the primary procedure group. The Kaplan-Meier survival estimates showed no significant difference in midterm survival in the elective or emergency setting between primary and redo surgery. The fact that some of these procedures necessitated a re-operation almost a decade after the primary procedure reinforces the need for close life-long surveillance. This is especially relevant in patients with Marfan syndrome who present at a younger age and are more prone to complications presenting as an emergency. In fact, it has been shown that Marfan patients have a 6-fold higher risk of re-operation compared to non-Marfanoid patients.20
Improvement in surgical expertise, advances in diagnostic aids, superior survival of patients after cardiac surgery, the growing enthusiasm for aortic valve preservation techniques and biological conduits, and the pathology of aortic dissection and the Marfan aorta will potentially continue to increase the number of re-operations on the aorta in the future. While attempts at aggressive management of the aneurysmal aorta during the primary procedure are recommended, it is still inevitable that more thoracic aortic re-operations will be carried out. It is reassuring to know that these can be performed in elective situations with low mortality and morbidity, but strategies need to be defined for minimizing the need for emergency intervention by adopting a regular program of life-long surveillance in all patients with a primary procedure on the thoracic aorta. It is also important to identify and follow up patients undergoing other cardiac procedures who are at increased risk of developing aneurysmal dilatation or dissection of the ascending aorta ± arch.
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REFERENCES
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- Dougenis D, Daily BB, Kouchoukos NT. Reoperations on the aortic root and ascending aorta. Ann Thorac Surg 1997;64:986–92.[Abstract/Free Full Text]
- Christenson JT, Schmuziger M, Simonet F. Reoperative coronary artery bypass procedures: risk factors for early mortality and late survival. Eur J Cardiothorac Surg 1997;11:129–33.[Abstract]
- Narayan P, Caputo M, Rogers CA, Alwair H, Mahesh B, Angelini GD, et al. Early and mid-term outcomes of surgery of the ascending aorta/arch: is there a relationship with caseload? Eur J Cardiothorac Surg 2004;25:676–82.[Abstract/Free Full Text]
- Pansini S, Ottino G, Forsennati PG, Serpieri G, Zattera G, Casabona R, et al. Reoperations on heart valve prostheses: an analysis of operative risks and late results. Ann Thorac Surg 1990;50:590–6.[Abstract]
- Kulshrestha P, Garb JL, Rousou JA, Engelman RM, Wait RB. Reoperative median sternotomy using a cast spreader. J Card Surg 1999;14:185–6.[Medline]
- Carrel T, Pasic M, Jenni R, Tkebuchava T, Turina MI. Reoperations after operation on the thoracic aorta: etiology, surgical techniques, and prevention. Ann Thorac Surg 1993;56:259–69.[Abstract]
- Bachet JE, Termignon JL, Dreyfus G, Goudot B, Martinelli L, Piquois A, et al. Aortic dissection. Prevalence, cause, and results of late reoperations. J Thorac Cardiovasc Surg 1994;108:199–206.[Abstract/Free Full Text]
- Ehrlich MP, Ergin MA, McCullough JN, Lansman SL, Galla JD, Bodian CA, et al. Results of immediate surgical treatment of all acute type A dissections. Circulation 2000;102(19Suppl 3):III248–52.
- Westaby S, Katsumata T, Vaccari G. Aortic root replacement with coronary button re-implantation: low risk and predictable outcome. Eur J Cardiothorac Surg 2000;17:259–65.[Abstract/Free Full Text]
- Kazui T, Washiyama N, Bashar AH, Terada H, Suzuki T, Ohkura K, et al. Surgical outcome of acute type A aortic dissection: analysis of risk factors. Ann Thorac Surg 2002;74:75–82.[Abstract/Free Full Text]
- Prenger K, Pieters F, Cheriex E. Aortic dissection after aortic valve replacement: incidence and consequences for strategy. J Card Surg 1994;9:495–9.[Medline]
- Vallely MP, Hughes CF, Bannon PG, Hendel PN, French BG, Bayfield MS. Composite graft replacement of the aortic root after previous cardiac surgery: a 20-year experience. Ann Thorac Surg 2000;70:851–5.[Abstract/Free Full Text]
- Eitz T, Kawohl M, Fritzsche D, Minami K, Raute-Kreinsen U, Korfer R. Aortic dissection after previous coronary artery bypass grafting. J Card Surg 2003;18:519–23.[Medline]
- von Segesser LK, Lorenzetti E, Lachat M, Niederhauser U, Schonbeck M, Vogt PR, et al. Aortic valve preservation in acute type A dissection: is it sound? J Thorac Cardiovasc Surg 1996;111:381–91.[Abstract/Free Full Text]
- Casselman FP, Tan ES, Vermeulen FE, Kelder JC, Morshuis WJ, Schepens MA. Durability of aortic valve preservation and root reconstruction in acute type A aortic dissection. Ann Thorac Surg 2000;70:1227–33.[Abstract/Free Full Text]
- Kirsch M, Soustelle C, Houel R, Hillion ML, Loisance D. Risk factor analysis for proximal and distal reoperations after surgery for acute type A aortic dissection. J Thorac Cardiovasc Surg 2002;123:318–25.[Abstract/Free Full Text]
- Kazui T, Washiyama N, Muhammad BA, Terada H, Yamashita K, Takinami M, et al. Extended total arch replacement for acute type a aortic dissection: experience with seventy patients. J Thorac Cardiovasc Surg 2000;119:558–65.[Abstract/Free Full Text]
- Hirotani T, Kameda T, Kumamoto T, Shirota S. Results of a total aortic arch replacement for an acute aortic arch dissection. J Thorac Cardiovasc Surg 2000;120:686–91.[Abstract/Free Full Text]
- Tan ME, Dossche KM, Morshuis WJ, Kelder JC, Waanders FG, Schepens MA. Is extended arch replacement for acute type a aortic dissection an additional risk factor for mortality? Ann Thorac Surg 2003;76:1209–14.[Abstract/Free Full Text]
- Bachet J. Acute type A aortic dissection: can we dramatically reduce the surgical mortality? Ann Thorac Surg 2002;73:701–3.[Free Full Text]
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ABSTRACT
INTRODUCTION
