Differential Effects of Hypothermia on Early and Late Epileptiform Events After Severe Hypoxia in Preterm Fetal Sheep

2007 ◽  
Vol 97 (1) ◽  
pp. 572-578 ◽  
Author(s):  
L. Bennet ◽  
J. M. Dean ◽  
G. Wassink ◽  
A. J. Gunn
Keyword(s):  
Marked Reduction ◽  
Epileptiform Activity ◽  
Neuronal Loss ◽  
Close Correlation ◽  
Recovery Phase ◽  
Early Recovery ◽  
Fetal Sheep ◽  
Specific Suppression ◽  
Head Cooling ◽  
Early Recovery Phase

Moderate cerebral hypothermia is consistently neuroprotective after experimental hypoxia-ischemia; however, its mechanisms remain poorly defined. Using a model of complete umbilical cord occlusion for 25 min in 0.7 gestation fetal sheep, we examined the effects of cerebral hypothermia (fetal extradural temperature reduced from 39.5 ± 0.2°C to <34°C; mean ± SD), from 90 min to 70 h after the end of the insult, on postocclusion epileptiform activity. In the first 6 h after the end of occlusion, fetal electroencephalographic (EEG) activity was abnormal with a mixture of fast and slow epileptiform transients superimposed on a suppressed background; seizures started a mean of 8 h after occlusion. There was a close correlation between numbers of these EEG transients and subsequent neuronal loss in the striatum after 3 days recovery ( r2 = 0.65, P = 0.008). Hypothermia was associated with a marked reduction in numbers of epileptiform transients in the first 6 h, reduced amplitude of seizures, and reduced striatal neuronal loss. In conclusion, neuroprotection with delayed, prolonged head cooling after a severe asphyxial insult in the preterm fetus was associated with potent, specific suppression of epileptiform transients in the early recovery phase but not of numbers of delayed seizures.

scholarly journals Magnesium sulfate reduces EEG activity but is not neuroprotective after asphyxia in preterm fetal sheep

2016 ◽  
Vol 37 (4) ◽  
pp. 1362-1373 ◽  
Author(s):  
Robert Galinsky ◽  
Vittoria Draghi ◽  
Guido Wassink ◽  
Joanne O Davidson ◽  
Paul P Drury ◽  
...  
Keyword(s):  
White Matter ◽  
Magnesium Sulfate ◽  
Marked Reduction ◽  
Neuronal Loss ◽  
Periventricular White Matter ◽  
Fetal Sheep ◽  
Eeg Activity ◽  
Fetal Movements ◽  
To Receive ◽  
Anticonvulsant Effects

Magnesium sulfate is now widely recommended for neuroprotection for preterm birth; however, this has been controversial because there is little evidence that magnesium sulfate is neuroprotective. Preterm fetal sheep (104 days gestation; term is 147 days) were randomly assigned to receive sham occlusion (n = 7), i.v. magnesium sulfate (n = 10) or saline (n = 8) starting 24 h before asphyxia until 24 h after asphyxia. Sheep were killed 72 h after asphyxia. Magnesium sulfate infusion reduced electroencephalograph power and fetal movements before asphyxia. Magnesium sulfate infusion did not affect electroencephalograph power during recovery, but was associated with marked reduction of the post-asphyxial seizure burden (mean ± SD: 34 ± 18 min vs. 107 ± 74 min, P < 0.05). Magnesium sulfate infusion did not affect subcortical neuronal loss. In the intragyral and periventricular white matter, magnesium sulfate was associated with reduced numbers of all (Olig−2+ve) oligodendrocytes in the intragyral (125 ± 23 vs. 163 ± 38 cells/field) and periventricular white matter (162 ± 39 vs. 209 ± 44 cells/field) compared to saline-treated controls ( P < 0.05), but no effect on microglial induction or astrogliosis. In conclusion, a clinically comparable dose of magnesium sulfate showed significant anticonvulsant effects after asphyxia in preterm fetal sheep, but did not reduce asphyxia-induced brain injury and exacerbated loss of oligodendrocytes.

scholarly journals The role of precipitation losses in producing the rapid early recovery phase of the Great Magnetic Storm of February 1986

1998 ◽  
Vol 103 (A4) ◽  
pp. 6801-6814 ◽  
Author(s):  
J. U. Kozyra ◽  
M.-C. Fok ◽  
E. R. Sanchez ◽  
D. S. Evans ◽  
D. C. Hamilton ◽  
...  
Keyword(s):  
Magnetic Storm ◽  
Recovery Phase ◽  
Early Recovery ◽  
Early Recovery Phase

Abstract 17270: Prognostic Impact of Ventricular Ectopy During the Recovery Phase of Stress Testing: A Meta-Analysis

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_1) ◽  
Author(s):  
Muhammad T Ayub ◽  
Muhammad S Khan ◽  
Sagar Ranka ◽  
Muhammad Ishaq ◽  
Muhammad F Khalid ◽  
...  
Keyword(s):  
Stress Testing ◽  
Meta Analysis ◽  
Recovery Phase ◽  
Prognostic Impact ◽  
Ventricular Ectopy ◽  
Early Recovery ◽  
Premature Ventricular Contractions ◽  
Risk Of Death ◽  
All Cause Mortality ◽  
Early Recovery Phase

Introduction: Ventricular ectopy after exercise, due to parasympathetic activity, predicts an increased risk of death in population-based cohorts. We sought to examine the composite risk of all cause mortality in patients with premature ventricular contractions (PVCs) in the early recovery phase of stress testing. Methods: PubMed, Medline & EMBASE were queried for all English language articles from 1993 to 2017. The primary outcome was incidence of all cause mortality in patients with frequent PVCs during recovery phase (RPV) of stress testing. Frequent PVCs were defined as the presence of seven or more ventricular premature beats/min, frequent ventricular couplets, ventricular bigeminy or trigeminy, or any other form of ventricular tachycardia or ventricular fibrillation. Meta-analysis of the main outcome was performed using a weighted random effects model. Results: A total of four observational studies including 38765 patients were retrieved. Data for 2065 patients with RPV was pooled. A comparative analysis of PVC vs Infrequent/Non-PVC group showed a calculated risk ratio for all cause mortality of 1.8 (95% CI 1.36-2.38; p=0.001). I 2 statistic for heterogeneity testing was 82.8% (Fig.1). Conclusion: Frequent premature ventricular contractions during early recovery phase of stress testing are associated with increased all cause mortality as compared to patients with infrequent or no PVCs.

Abstract 2142: Diagnostic and Prognostic Value of Augmented ST-Segment Elevation at Exercise Testing in Patients with Brugada Syndrome

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Hisaki Makimoto ◽  
Eiichiro Nakagawa ◽  
Hiroshi Takaki ◽  
Kenichiro Yamagata ◽  
Hiro Kawata ◽  
...  
Keyword(s):  
Exercise Testing ◽  
Brugada Syndrome ◽  
Recovery Phase ◽  
Peak Exercise ◽  
Early Recovery ◽  
St Segment Elevation ◽  
St Segment ◽  
History Of ◽  
Diagnostic And Prognostic Value ◽  
Early Recovery Phase

Background : It has been reported that ST-segment elevation was augmented at early recovery phase or at peak exercise during exercise testing in some patients with Brugada syndrome (BrS), but its diagnostic and prognostic value has not fully been clarified. Methods : Treadmill exercise testing (TMT) was conducted in 93 patients (pts) with BrS (22 documented VF, 31 syncope alone, and 40 asymptomatic; 91 males, 46±14 years) and 22 healthy control subjects (20 males, 48±14 years, 11 with incomplete right bundle branch block (RBBB) and 4 with complete RBBB). Results : The augmentation of ST-segment elevation ≥0.05mV in V1-V3 leads compared with that before exercise was observed at early recovery phase (1– 4 minutes at recovery phase) in 32 BrS pts (34%, Group1), at peak exercise in 8 BrS pts (9%, Group 2), but not in either the remaining 53 BrS pts (57%, Group 3) or 22 control subjects. There were no significant differences among the 3 BrS groups in the baseline clinical (age, gender, family history of sudden death, SCN5A mutation), electrocardiographic (PR, QRS duration, QTc interval and ST amplitude), and electrophysiologic (AH, HV interval, and VF induction) variables except for the positive ratio of signal averaged ECG (87%, 48%, 63%; P= 0.001). No significant difference was observed in the proportion of previous cardiac events (VF/syncope/asymptomatic; 6/12/14, 0/3/5, 16/16/21, respectively for Group 1, 2, and 3). During 76.0, 74.8, and 52.0 months follow-up, VF occurred in 12/32 (38%) pts of Group1, 0/8 (0 %) pts of Group2, and 10/53 (19%) pts of Group3. Augmentation of ST-segment elevation at early recovery phase was a significant and an independent predictor for subsequent VF occurrence (12/32 (38%) in Group1 vs. 10/61 (16%) in Group2 and 3; hazard ratio [HR]= 1.68; P=0.014), especially in 31 pts with a history of syncope alone (6/12 (50%) in Group1 vs. 1/19 (5%) in Group2 and 3; HR=3.44; P=0.004). Conclusions : Our data suggest that augmentation of ST-segment elevation at early recovery phase during exercise testing can be a predictor of poor prognosis in patients with Brugada syndrome, especially in those with a history of syncope alone.

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