Canadian HealthCare Mall: Results of Relation Between Neurocognitive Impairment, Embolic Load, and Cerebrovascular Reactivity
HITS
In the on-pump group, the mean number of HITS was 335.1 ± 333.5 (range, 24 to 1,229), whereas in the off-pump group, the mean number of HITS was 144.7 ± 180.4 (range, 5 to 632). This difference was significant (Z = — 2.698; p < 0.01).
Since all patients were monitored bilaterally, we could compare the HITS detection in the left and right MCAs. For the on-pump group, we counted 179 ± 227 HITS (53%) in the left MCA and 156 ± 151 HITS (47%) in the right MCA. This difference was not significant. In off-pump patients, HITS tended to be more numerous on the right MCA (106 ± 149; 73%) compared to the left MCA (39 ± 62; 27%), although this trend failed to reach significance (p = 0.057). After square-root transformation of the HITS count to obtain a normal distribution, a repeated-measures, multivariate analyses of variance with eight different surgical maneuvers of on-pump CABG as within-subjects factor was performed and revealed a main effect of surgical maneuver (F = 8.128, p < 0.01). When the different surgical maneuvers of on-pump CABG were assessed separately with paired t tests, significantly more HITS were detected immediately after aortic cannulation (Table 2). Significantly fewer HITS were found after cross-clamping. When cumulating the percentage of HITS associated with the different stages of the operation, 13.9% of the total number of HITS was explained.
Effect of Surgical Technique on Cognition
The neuropsychological testing results for the preoperative, early, and late postoperative periods are presented in Table 3. Neuropsychological data were analyzed on a general level. Patients in the on-pump group showed a higher IQ (p < 0.01), less tobacco use (p < 0.05), a higher number of diseased vessels (p < 0.05), and a higher number of grafts (p < 0.01). For further analysis of cognitive measures in this group, these variables were included as covariates. MANCOVAs with time of neuropsychological assessment (preoperative vs early postoperative and preoperative vs late postoperative) as within-subjects factor, type of surgery as between-subjects factor, and differences between both groups as co-variates revealed no main effect of time, no main effect of surgery, and no interaction effects. Do you dream of becoming a doctor?
According to the 20% definition, 60% from the total group had a cognitive decline 6 days after surgery, 59.4% in the on-pump group and 61.2% in the off-pump group. After 6 months, 24.2% still had a cognitive decline, 31.8% in the on-pump group and 9.1% in the off-pump group.
For the results according to the CII, we refer to Tables 4, 5. Early neurocognitive impairment was most frequently observed on the blocks tap test and the line bisection test. Six months after surgery, the CII was significantly different in the on-pump group vs the off-pump group (Z = — 2.24, p < 0.05) with less neurocognitive tests that remained impaired in the off-pump group. Neurocognitive impairment was most frequently observed on the line bisection test (on-pump group), trail-making test, and blocks tap test (on-pump and off-pump groups) after 6 months.
BFV Before and After Surgery
Percentages change for the preoperative, early postoperative, and late postoperative period for the total group are presented in Table 6. MANCOVAs with time of BFV measurements (preoperative vs early postoperative and preoperative vs late postoperative on absolute rest values, absolute activation values, and percentage change) as within-subjects factor, type of surgery as between-subjects factor and IQ, tobacco use, number of diseased vessels, and number of grafts as covariates revealed no main effect of time, no main effect of surgery, and no interaction effects.
Relation Between Number of HITS With Cognitive Performance and BFV
We tested whether patients showing significant cognitive decline (as defined by the 20% definition) received significant more HITS during operation than patients showing no significant decline. A t test with total number of HITS (log-transformed) as dependent variable and absence/presence of cognitive decline as independent variable showed no significant differences between both groups.
In addition, we tested if there was a significant association between HITS and CII. A Spearman p correlation was performed for total number of HITS and CII. No significant correlations were found.
With regard to the BFV variables, we investigated whether the number of HITS was related to changes in pre-cerebrovascular reactivity to post-cerebrovascular reactivity. We calculated Pearson correlations between the total number of HITS (log-transformed variable) and BFV values (preoperative BFV percentage change minus early postoperative BFV percentage change, and preoperative BFV percentage change minus late postoperative BFV percentage change). No significant correlations were found.
An explorative multivariate regression analysis with log-transformed number of HITS as the dependent variable and mean activation BFV value (sum of five BFV tasks left and right side divided by 10), left ventricle ejection fraction, age, hypertension, and number of diseased vessels as clinically relevant independent variables revealed that mean activation BFV value (p = -0.387, t = — 3.037, p < 0.01), number of diseased vessels (p = 0.319, t = 2.469, p < 0.05), and left ventricle ejection fraction (P = — 0.27, t = — 2.125, p < 0.05) are significant predictors for number of HITS. The model explained 34.2% of the variance. We also found significant negative correlations between the number of HITS as well as between mean BFV activation value and left ventricle ejection fraction. This means that the lower the mean activation BFV value and left ventricle ejection fraction, the higher the embolic load.
Table 2—Occurrence of HITS
Variables | Average HITS Count (% of Total No. of HITS) |
Aortic cannulation | 9.24 (2.9) |
ECC on | 5.61 (1.8) |
Cross-clamp on | 0.67 (0.2) |
Cross-clamp off | 5.7 (1.8) |
Partial clamp on | 5.2 (1.6) |
Partial clamp off | 4.9 (1.6) |
ECC off | 6.6 (2.1) |
Aortic decannulation | 6.1 (1.9) |
Table 3—Neuropsychological Test Results in On-Pump Group Compared to Off-Pump Group After 6 Days and 6 Months
Tests/Groups | Preoperative | 6 Days | 6 Months |
Auditory verbal learning test | |||
On-pump | 44.8 ± 8.5 | 42.6 ± 9.2 | 48.5 ± 9.5 |
Off-pump | 41.72 ± 10.7 | 43.2 ± 7.9 | 49.6 ± 9.2 |
Block taps test | |||
On-pump | 37.7 ± 19.9 | 43.9 ± 22.2 | 35.8 ± 22.5 |
Off-pump | 41.8 ± 16.0 | 53.2 ± 18.9 | 34.5 ± 19.7 |
Trail-making test part B | |||
On-pump | 121.3 ± 67.1 | 134.4 ± 65.3 | 100.1 ± 38.7 |
Off-pump | 154.8 ± 96.6 | 116.9 ± 36.1 | 123.2 ± 88.6 |
Grooved pegboard test | |||
On-pump | 183.5 ± 50.2 | 209.9 ± 58.4 | 108.2 ± 53.7 |
Off-pump | 197.3 ± 36.4 | 218.2 ± 52.4 | 123.2 ± 88.6 |
Judgment of line orientation | |||
On-pump | 23.7 ± 3.8 | 23.5 ± 4.5 | 24 ± 4.6 |
Off-pump | 23.7 ± 4.2 | 23.1 ± 4.4 | 25.2 ± 3.9 |
Line bisection test | |||
On-pump | 68.2 ± 24.8 | 74.5 ± 28.5 | 65.9 ± 20.3 |
Off-pump | 69.0 ± 27.7 | 71.9 ± 20.4 | 64 ± 34.4 |
Controlled oral word association test | |||
On-pump | 29.1 ± 8.5 | 28.6 ± 7.7 | 33.3 ± 8.9 |
Off-pump | 22.4 ± 6.1 | 24.9 ± 8.7 | 25.9 ± 6.4 |
Table 4—Results According to CII After 6 Days
CII | Total Group | On-Pump Group | Off-Pump Group |
0 | 18 | 15.6 | 22.2 |
1 | 22 | 25 | 16.7 |
2 | 34 | 37.5 | 27.8 |
3 | 18 | 12.5 | 27.8 |
4 | 6 | 6.3 | 5.6 |
5 | 2 | 3.1 | 0.0 |
Table 5—Results According to CII After 6 Months
CII | Total Group | On-Pump Group | Off-Pump Group |
0 | 36.4 | 22.7 | 63.6 |
1 | 39.4 | 45.5 | 27.3 |
2 | 24.2 | 31.8 | 9.1 |
Table 6—Percentages Changes Over the Operative Periods for the Total Group
Test/Side | Preoperative (n = 66) | Early Postoperative (n = 63) | Late Postoperative (n = 44) |
NLV | |||
Left | 6.15 ± 9.41 | 6.41 ± 6.75 | 6.36 ± 9.45 |
Right | 4.21 ± 8.47 | 4.73 ± 7.07 | 5.47 ± 7.25 |
Visual searching | |||
Left | 10.38 ± 7.81 | 8.56 ± 4.45 | 8.93 ± 7.15 |
Right | 11.42 ± 8.46 | 8.93 ± 5.29 | 10.78 ± 8.15 |
Syntactic sentence construction | |||
Left | 9.62 ± 8.21 | 8.55 ± 4.49 | 8.17 ± 8.5 |
Right | 7.17 ± 7.89 | 6.52 ± 5.69 | 6.89 ± 7.35 |
Three-dimensional puzzle | |||
Left | 14.22 ± 8.70 | 11.81 ± 6.11 | 15.00 ± 7.43 |
Right | 17.07 ± 8.43 | 13.70 ± 7.08 | 16.85 ± 7.90 |
Controlled oral word association test | |||
Left | 7.36 ± 10.08 | 4.79 ± 6.36 | 7.91 ± 10.75 |
Right | 3.45 ± 9.16 | 4.15 ± 11.87 | 5.10 ± 7.22 |