| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
J Thorac Cardiovasc Surg 2005;129:591-598
© 2005 The American Association for Thoracic Surgery
Cardiopulmonary Support and Physiology |
Department of Surgical and Perioperative Science, Heart Center, Cardiothoracic Division, Umeå University Hospital, Umeå, Sweden
Received for publication March 18, 2004; revisions received July 6, 2004; accepted for publication July 15, 2004. * Address for reprints: Patrik Boivie, MD, Department of Surgical and Perioperative Science, Heart Center, Cardiothoracic Division, Umeå University Hospital, S-901 85 Umeå, Sweden (E-mail: patrik_boivie{at}hotmail.com).
 |
Abstract |
|---|
 Top Abstract MethodsResultsDiscussionReferences |
|---|
METHODS: During a 2-year period, 2641 consecutive cardiac surgery cases were analyzed. Patients positive for cerebrovascular accident were extracted from a database designed to monitor clinical symptoms. A protocol was used to confirm symptom data with the correct diagnosis in patient records. Patients were subdivided into 3 groups: control, immediate cerebrovascular accident, and delayed cerebrovascular accident.
RESULTS: Among pooled patients, immediate and delayed cerebrovascular accidents were 3.0% and 0.9%, respectively. The expected predisposing factors behind immediate cerebrovascular accidents were significant, although the type of operation affected this search. Aortic quality was a strong predictor (P < .001). The rate of delayed cerebrovascular accident was unaffected by surgery group. Left-sided symptoms of immediate cerebrovascular accident were approximately twice as frequent (P = .016) as on the contralateral side. This phenomenon was observed for pooled patients and for isolated coronary bypass procedures (n = 1882; P = .025).
CONCLUSIONS: Immediate cerebrovascular accident and aortic calcifications are linked. The predominance of left-sided symptoms may suggest that aortic manipulation and anatomic mechanisms in the aortic arch are more likely to cause cerebrovascular accidents than effects from cannula stream jets.
Major surgical and scientific efforts are focused on the issue of aortic calcification and technical methods to avoid this problem,13,14 such as off-pump surgery,15,16 aortic ultrasound scanning,17 single clamp procedures,18 automated graft connectors,19 and intra-aortic filtering.20 Ultrasound scanning has the advantage of visualizing not only hard calcifications, but also soft plaques not identified by palpation. The aortic clamp has been suggested to contribute to mechanical trauma as evaluated both clinically and experimentally.6,12 However, an opposing mechanism suggests that unfavorable stream jets at the tip of the aortic cannula dislodge particles from the vascular wall.21-23 This speculative assumption was based on findings that left-hemispheric lesions, ie, right-sided symptoms, are more often involved in immediate CVA than right-hemispheric lesions, assuming a particle route through the left common carotid artery rather than the brachiocephalic trunk.22 The question about the anatomic focus of CVA in cardiac surgery has been addressed previously and with contradicting results that suggested either a right hemispheric or a posterior location,24,25 although these studies were based on limited patient numbers and low statistical power.
In view of the contradiction regarding possible CVA mechanisms, our aim was to investigate neurologic symptoms after cardiac surgery. The study was focused on possible side differences from the clinical pattern of CVA and how this phenomenon varied between immediate and delayed CVA.
|
Methods |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
The studied population had an average age of 65.6 ± 10.3 years and contained 72.6% men. The average weight was 79.4 ± 14.2 kg. Demographic data are shown in Table 1, with subdivision into controls and the 2 groups of CVA.
|
Database recordings and protocol
The database had a prospective design to monitor clinical symptoms in all operated patients. Preoperative data were followed by daily entry of information from the operating room, the intensive care unit, and the ward. Inputs were from surgeons, anesthetists, perfusionists, nurses, and physiotherapists. The same parameter could therefore have duplicate inputs in the database, and this possibly increased the precision of the more important findings. A synthesis of these multiple-input parameters was performed in the data processing. Records of all patients in the database with reported CVA were collected for review in a retrospective fashion. A protocol was designed to follow up the events in a systematic order, to verify symptom data with clinical diagnosis, and to subdivide patients into immediate and delayed CVA. The parameters "cerebral history," "peripheral vascular disease," and "pulmonary disease" referred to anamnestic information by the patient or from patient records for any previous ischemic cerebral event, regardless of type; peripheral vascular disease with or without operation; and any form of verified restrictive or obstructive disease or positive laboratory recordings, respectively.
Classification of CVA
The patients were subdivided into 3 groups: control, immediate CVA, and delayed CVA. Immediate CVA was defined as positive neurologic symptoms apparent at extubation after surgery. Delayed CVA was defined as having a free interval after extubation. Duration of neurologic symptoms was monitored to subdivide into transient ischemic attack lasting less than 24 hours versus CVA longer than 24 hours. The definitions were according to routine guidelines.26 Because of few observations of transient ischemic attack (3 each in the immediate and delayed groups), these were pooled together with CVA in the data presentation. Patients with borderline symptoms and uncertain diagnosis were grouped as control subjects. For obvious CVA, an experienced surgeon or anesthetist confirmed the diagnosis. In less obvious cases, computed tomographic scans were performed (76% of all cases) or a consultant neurologist confirmed the diagnosis (47% of cases). In 65% of immediate and 74% of delayed events, the computed tomographic scan confirmed the CVA.
Statistical analysis
Mean values ± SD and frequencies are given throughout. Typically, the statistical analysis compared 3 groups: control, immediate CVA, and delayed CVA. For parametric data, 1-way analysis of variance was conducted with Duncan post hoc analysis. Nonparametric and nominal data were analyzed by means of 3-column contingency tables and by a log-linear model and maximum likelihood 
2 output. Post hoc analysis was conducted by excluding 1 group to restrain the statistical model. If there were few observations, Fisher exact tests were used. Statistica (StatSoft, Tulsa, Okla), version 6.1, was used throughout.
|
Results |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
|
|
|
Patterns of CVA
CVA patterns are presented in Table 5. Left-sided symptoms (arm and leg) were almost twice as frequent as contralateral symptoms in the immediate CVA group. This was seen among pooled patients (P = .016) and among isolated CABG (P = .025). A similar numeric pattern was seen for delayed CVA, although this was not significant. The side difference was numerically similar for aortic valve replacement (AVR) and CABG/AVR combinations, although the numbers of CVAs for these groups were insufficient to yield significance.
|
|
Discussion |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
There is strong evidence that embolic particles are dislodged because of aortic manipulation6 and that aortic quality correlates significantly with immediate CVA.7,27 However, in contrast to this theory is the proposed mechanism that unfavorable stream jets induced by the aortic cannula dislodge embolic material.22 The latter assumption was based on findings that left-hemispheric CVAs dominate over the contralateral side.22 The side difference was interpreted in terms of the anatomic location of the tip of the cannula in the vicinity of the left common carotid artery.22
We found, in contrast,22 and despite the use of standard curved-tip/end-hole aortic cannula, a preponderance of left-sided symptoms with immediate CVA, ie, the right hemisphere. The CVA phenomenon was significant for pooled groups of surgery, as well as for isolated CABG, the latter of which dominated the statistical material. Similar numeric differences were, however, observed for AVR and CABG/AVR combinations, but this did not reach significance because of fewer observations. For comparison, side differences in CVA were not seen after surgery on the ascending aorta (data not shown).
As expected, immediate CVA had a strong link to observed aortic calcifications. It is tempting to speculate that the previous and combined observations point toward embolic mechanisms due to manipulation of the ascending aorta. In theory, particles are tangentially expelled into the brachiocephalic trunk rather than being dislodged by cannula stream jets into the perpendicularly branched left common carotid artery.22
In consonance with our data, a small study by Sotaniemi24 demonstrated that the right hemisphere was involved in 71% of cases of brain damage after cardiac surgery. The question about possible side differences for delayed CVA has not, to our knowledge, been addressed previously. It is interesting to note that we found a similar percentage difference of right-to-left symptoms in delayed CVA as for immediate CVA, although this did not reach significance because of insufficient numbers. It can be speculated that blood clots formed in the cavities of the heart are predominantly expelled tangentially into the brachiocephalic trunk rather than into the left common carotid artery, similar to the embolic route of immediate CVA.
In this study, immediate and delayed CVA occurred in approximately 3.0% and 0.9% of patients, respectively. Delayed CVA seemed unaffected by the type of surgery, whereas immediate CVA varied markedly between surgery subgroups. For isolated CABG, the percentage was only approximately half of that for pooled patients. Thus, although CABG accounted for 71% of the procedures, most CVAs (56%) occurred in the more complex forms of surgery. The observed CVA rates are similar to what has been previously reported,28 although both higher29 and lower3 rates have been described. AVR produced a significantly higher incidence of immediate CVA than did isolated CABG, a pattern that again confirms previous findings.29 Combination procedures of CABG/AVR were associated with unexpectedly high rates of immediate CVA, at 7.5%, but these results are nearly identical to those reported by Bucerius and associates.29 The finding that CVA rates add up for combined procedures is in consonance with previous suggestions.3 The use of CPB and the possible benefit of OPCAB over on-pump procedures did not yield significance in this study. Even so, all CVAs occurred among patients exposed to CPB, whereas the control group contained all OPCAB procedures.
Mechanisms behind CVA after cardiac surgery seem complex. This issue has been extensively studied in the past.27,29 In general, mechanisms can be subdivided into those relating to patient demographics and those caused by the operation. Immediate and delayed CVA were here found to represent different diseases in view of both demographic and surgical data. Our data confirm many previous reports. In brief, age, history of CVA, vascular disease, pulmonary disease, left ventricular function, New York Heart Association class, and high Higgins scores were associated with immediate CVA. Among procedure-related mechanisms, aortic wall calcifications; time of operation, CPB, and clamp; and cardioplegia type and administration all correlated with immediate CVA. However, many of these mechanisms disappeared when isolated CABG procedures were extracted for analysis. Only aortic quality and the need for inotropic support remained significantly associated with immediate CVA.
The sex difference suggesting more frequent delayed but not immediate CVA among women was interesting. Hogue and colleagues3 found a nearly 6.9-fold increased risk for immediate CVA among women, a finding that was not confirmed in our study. CVA is a critical complication of cardiac surgery that affects the patient outcome and requirement for resources, such as for intensive care. As expected, hospital and 1-year mortality were significantly higher in both the immediate and delayed CVA groups versus controls. One-year mortality was approximately twice the rate for hospital death. A CVA resulted in approximately a fourfold to fivefold increase in death rate whether the CVA was immediate or delayed.
The study is limited from its retrospective design that included all types of major operations during a defined period of time. The design resulted in a heterogeneous patient cohort subdivided into subgroups of procedures, among which isolated CABG dominated. Further, science based on data registries is less precise and is limited to selected parameters.
In conclusion, immediate and delayed CVA represented 2 different groups of disease that related to multiple and somewhat different risk factors. Immediate CVA was more frequent than the delayed form, and more complex operations increased the risk dramatically. Left-sided symptoms were twice as frequent as on the contralateral side, and it can be speculated that this finding points toward aortic manipulation and anatomic mechanisms in the aortic arch.
|
Footnotes |
|---|
|
References |
|---|
|
TopAbstractMethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  B. Zingone, E. Rauber, G. Gatti, A. Pappalardo, B. Benussi, L. Dreas, and L. Lattuada The impact of epiaortic ultrasonographic scanning on the risk of perioperative stroke. Eur. J. Cardiothorac. Surg., May 1, 2006; 29(5): 720 - 728. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Boivie, M. Hansson, and K. G. Engstrom Intraluminal aortic manipulation by means of intra-aortic filter, cannulation, and external clamp maneuvers evaluated versus dislodged embolic material J. Thorac. Cardiovasc. Surg., February 1, 2006; 131(2): 283 - 289. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
