Interact CardioVasc Thorac Surg 2009;9:246-250. doi:10.1510/icvts.2008.194811
© 2009 European Association of Cardio-Thoracic Surgery
Institutional report - Aortic and aneurysmal |
Aortic root surgery in combination with hypothermic circulatory arrest: preserve or replace the aortic valve in the context of postoperative neurological outcome? A case match comparison
Nawid Khaladj*,1,
Issam Ismail1,
Malakh Shrestha,
Sven Peterss,
Maximilian Pichlmaier,
Klaus Kallenbach,
Axel Haverich and
Christian Hagl
Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
Received 24 September 2008;
received in revised form 13 March 2009;
accepted 14 April 2009
1 Both authors contributed equally to this work. 
 This work was supported by the German Research Foundation (HA 2971/2-2).
*Corresponding author. Tel.: +49-511-532-6581; fax: +49-511-532-5404.
E-mail address: Khaladj.Nawid{at}mh-hannover.de (N. Khaladj).
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Abstract
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The objective of this study was to compare the results of elective composite (C) vs. David (D) operations in patients requiring additional aortic arch surgery using hypothermic circulatory arrest (HCA) and selective antegrade cerebral perfusion (SACP), with the focus on postoperative neurological outcome and quality of life (SF-36). Between November 1999 and March 2006, 333 patients underwent aortic root surgery and ascending aortic replacement with HCA and SACP at our institution. Out of these patients, 46 were matched with respect to age, gender, HCA-time and year of surgery. Two patients, one in each group, died during hospital stay (4%), with no late deaths. Follow-up was completed in 95% [64 (6–90) months]. Cardiopulmonary bypass (CPB) time (141 min vs. 168 min, P=0.007) and aortic cross-clamp time (99 min vs. 123 min, P=0.004) were significantly longer in the David-group. The incidence of temporary neurological dysfunction (TND 7%: D n=1, C n=2) was not different between groups, no permanent dysfunction could be detected. Follow-up SF-36 scores were comparable. The combination of aortic arch surgery with more time consuming valve sparing aortic root surgery does not increase the risk for adverse outcome applying comparable periods of HCA and SACP.
Key Words: Aortic root surgery; Composite replacement; David operation; Hypothermic circulatory arrest; Case match study
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1. Introduction
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The gold standard for the replacement of the aortic root is the implantation of a mechanical conduit, as described by Bentall and De Bono [1]. Excellent long-term results favour this technique especially in younger patients [2]. However, need for life-long anticoagulation and the increased risk for thromboembolic events are the major drawbacks of this technique [3]. Therefore, Galla and co-workers published the technique of a biological homemade conduit, avoiding life-long anticoagulation with coumadine, with no need for re-operation during follow-up [4]. In 1992, David and Feindel published a technique of aortic valve sparing re-implantation for replacement of an aneurysmatic root in patients with morphologically impaired valve cusps [5]. This technically demanding and more time consuming procedure has led to excellent results at our institution [6].
In cases where the aortic arch is involved in the underlying pathology, hypothermic circulatory arrest (HCA) has to be applied for organ protection, a potential risk factor for postoperative neurological disorders. Together with the more time consuming aortic valve sparing technique, associated with prolonged cardiopulmonary bypass (CPB) times, the risk for neurological complications may be higher, despite the fact that additional cerebral protection methods are applied [7].
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2. Patient and methods
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This study was approved by the institutional review board. All patients gave written informed consent.
Between November 1999 and March 2006, 333 patients underwent aortic root and ascending aortic surgery with HCA and selective antegrade cerebral perfusion (SACP) at our institution. Aortic valve replacement was performed in 207 patients, the David-technique was applied in 95 patients. Over the study period, a total of 251 patients received the David-I procedure at our institution.
To analyze the influence of HCA on neurological outcome in patients that underwent an elective aortic valve sparing operation in comparison to composite replacement, matched pairs were established with similar preoperative conditions. Matching criteria were gender, age at operation (±5 years), time point of operation (±2 years) and duration of HCA (±5 min). Patients who underwent emergency surgery, redo aortic surgery or those with concomitant carotid artery disease were excluded. Using this method, 23 matched pairs were identified. Patient selection was performed by an independent party. The aortic root procedure had no impact on the HCA time. Therefore, there is no risk of a potential selection bias. Patient characteristics of the matched pairs are shown in Table 1.
All patients underwent standard preoperative examinations as described previously [8].
2.1. Operative procedure
All operations were performed through a median sternotomy. Details of the CPB and HCA/SACP protocol as performed in our institution have been published previously [7]. Briefly, after systemic heparinisation, cannulation of the ascending aorta/aortic arch and right atrium was performed, CBP was established and the patient cooled to the target temperature around 27±1.4 °C. Cold blood cardioplegia was administered directly into the coronary ostia after aortic cross-clamping and opening of the ascending aorta. The aortic root was inspected and decision for valve sparing or composite replacement was made according to the pathology. After reaching the anticipated HCA temperature, CPB was stopped, the aorta was opened, and the arterial cannula removed. After exploration of the aortic arch, the patient was placed in Trendelenburg position and two 15 F retrograde cardioplegic catheters (RCSP MR 20, Medtronic, Minneapolis, MN, USA) were introduced under visual control into the innominate and left carotid arteries. The arch was repaired according to the pathology and the surgeon's preference. CPB was re-established for re-warming in an antegrade fashion after the arch repair by direct cannulation of the graft and meticulous de-airing of the supraaortic vessels. During cooling and re-warming, aortic root surgery was performed as determined by the concomi- tant pathology to avoid extended CPB times. The aortic root surgery was performed in a standardized manner as described before [9].
2.2. Neurological evaluation
Analysis was focused on discriminating between permanent neurological dysfunction (PND) (frank strokes) and temporary neurological deficits. Patients were considered to have PND if they exhibited the onset of focal deficits postoperatively or were found to have a focal lesion confirmed by means of CT scanning or MR imaging of the brain.
Temporary neurological dysfunction (TND) was defined according to Ergin and co-workers as a symptom complex of postoperative confusion, agitation, delirium, prolonged obtundation or transient Parkinsonism with negative results upon imaging of the brain.
2.3. Follow-up
All patients were contacted by phone, as well as the referring cardiologist for medical details. Follow-up was performed using a standardized questionnaire for postoperative complications as well as the short form of the SF-36 questionnaire for assessment of quality of life.
Infectious, thromboembolic, and bleeding complications were recorded as required by the guidelines of the American Association for Thoracic Surgery/Society of Thoracic Surgeons.
2.4. SF-36 questionnaire
The SF-36 questionnaire is a well-known questionnaire for measuring health status. The issues it explores with the 36 questions apply to people having many types of treatment, and in all the different states of health. The questions are designed to be easy to understand and relevant to most people's lives. The 36 questions have been carefully chosen to measure all the aspects of health and well-being. Questions ask about patient's physical functioning, amount of pain experience, energy levels and mood. The questions also try to understand how patient's health is affecting the ability to enjoy social life or to manage everyday tasks.
2.5. Statistical analysis
Results were expressed as mean±S.D., median and range or percentage, respectively. Furthermore, the 95% confidence intervals (CI) were calculated. Statistical analysis was performed using Student's t-test, Mann–Whitney or  2-test for comparison between groups, as appropriate. A P<0.05 was considered to be significant. Statistical analysis was performed using SPSS 14.0 software (SPSS Inc, Chicago, IL, USA).
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3. Results
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In each group, one patient died during hospital stay (4% 30-day mortality). The reason was unknown (presumably lung embolism) in one patient (autopsy was denied by the relatives) in one and low cardiac output following myocardial infarction in the other patient. No PND occurred in this subset of patients. A total of 10 biological and 13 mechanical composites were implanted.
Intraoperative parameters were significantly longer in the David-group regarding CBP (P=0.007) and aortic X-clamp time (P=0.004) (Fig. 1). Further intra and postoperative parameters were comparable between groups (Table 2).
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Fig. 1. Cardiopulmonary bypass (CPB) and aortic cross-clamp (X-clamp) times. Data are plotted as mean and S.D.
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3.1. Follow-up
Two patients were lost for follow-up in each group (96% complete follow-up). There were no late deaths. Despite the fact that patients were matched for year of surgery, median follow-up was longer in the composite-group [68 (8–87) months vs. 54 (9–90) months, P=0.09]. However, during follow-up no valve-related problems occurred. Embolic events (stroke) occurred in one patient of the David-group (no anticoagulation). Three patients of the mechanical composite-group had minor bleeding problems with no need for hospitalisation.
Last echocardiography revealed excellent valve functions in all patients receiving a mechanical as well as biological composite. In the David-group, 20 patients had no significant aortic insufficiency (AI 0-I), one patient showed AI grade II, with currently no need for re-operation (Table 3).
Quality of life values were comparable between groups (Fig. 2).
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4. Discussion
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Different surgical approaches for aortic root pathologies are currently available and were routinely applied. Most of them have excellent operative as well as long-term results [2, 4, 6]. However, aortic surgery requiring additional hypothermic circulatory is associated with prolonged CPB-times due to moderate or deep temperatures that are necessary for adequate organ protection. This may increase the individual risk for neurological complications, whereas some studies negate this hypothesis [10].
Valve sparing procedures are technically demanding and therefore also associated with a prolonged CPB and aortic X-clamp time, as demonstrated in this study as well as a previous study of our group [11]. The risk of CPB itself on the neurology integrity is controversially discussed. Different studies revealed a higher incidence of neurological disorders after prolonged CPB times. With the additional negative effects of HCA, the risk for adverse neurological events may therefore be higher [12].
The aim of this study was not to elucidate the best surgical approach for aortic root surgery since this has been done in several previous studies [11, 13]. However, none of these studies were focussed on the additional risk of prolonged CPB times that may occur when HCA alone or in combination with SACP is applied.
At our institution, aortic root and aortic arch surgery has been studied for years in clinical as well as experimental settings [6, 14]. The operative procedures are standardized for the root procedure as well as cerebral and organ protection [7, 9]. Out of our database, a subset of patients was selected for the present study. Care was taken that preoperative parameters that were well known to have an impact on adverse outcome (age, gender and previous neurological events) were comparable in both groups. This was proven by statistical analysis as well as the calculation of CI. With a low early mortality and no late death, the overall mortality rate is acceptable. No permanent neurological disorders occurred in our patient cohort during hospital stay, supporting previous findings that permanent neurological complications are related to the patients previous status and not the duration of HCA or the applied brain protection technique alone [12]. With an incidence of seven percent of TND in this subset of patients, that resolved completely before discharge, the results are very encouraging. The problem of TND detection in this context has been discussed before, since several studies revealed a different incidence of TND, which is presumably due to the fact that no standard detection battery exists. Since there are no statistical differences between groups, we are convinced that the incidence of this phenomenon is not related to the relative short CPB, HCA and SACP-times in this cohort.
During follow-up, no major bleeding events related to the coumadine therapy occurred, but minor bleedings were not unexpected. However, none of the patients required hospitalization or blood transfusions. Echocardiography showed excellent function of either the implanted or preserved valve with no valve related complications or need for re-operation so far. Excellent quality of life results could be revealed in our patient cohort, independent of the procedure applied. Postoperative medication with warfarin in the patients with a mechanical conduit had no impact on quality of life compared with those who received a biological valved conduit. Similar results were demonstrated by Stalder and co-workers in a current study [15]. In their experience, aortic root surgery is not associated with an impaired quality of life compared to different and other kinds of aortic surgery despite the more time consuming and technically demanding procedure. However, no David procedures were included in their study.
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5. Conclusions
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The aortic valve can be preserved in patients undergoing additional aortic surgery with an acceptable mortality and morbidity even when short periods of HCA in combination with SACP are applied for aortic arch surgery. Despite prolonged CPB and aortic cross-clamp times the outcome was comparable between groups. Nevertheless, CPB time itself had an independent impact on mortality during aortic surgery, including HCA [8]. This has to be kept in mind for selection of the procedure according to the patient's status. Excellent mid-term results with a comparable quality of life cannot favour a technique from the data presented here. However, even technical demanding procedures in selected patients and experienced hands do not increase the risk for adverse neurological outcome.
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References
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Abstract
1. Introduction
