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BACKGROUND: Preimplantation balloon aortic valvuloplasty (BAV) is considered a routine procedure during transcatheter aortic valve implantation (TAVI) to facilitate prosthesis implantation and expansion; however, it has been speculated that fewer embolic events and/or less hemodynamic instability may occur if TAVI is performed without preimplantation BAV. The aim of this study was to systematically review the clinical outcomes associated with TAVI undertaken without preimplantation BAV. METHODS AND RESULTS: We conducted a search of Medline and Embase to identify studies that evaluated patients who underwent TAVI with or without preimplantation BAV for predilation. Pooled analysis and random-effects meta-analyses were used to estimate the rate and risk of adverse outcomes. Sixteen studies involving 1395 patients (674 with and 721 without preimplantation BAV) fulfilled the inclusion criteria. Crude device success was achieved in 94% (1311 of 1395), and 30-day all-cause mortality occurred in 6% (72 of 1282) of patients. Meta-analyses evaluating outcomes of strategies with and without preimplantation BAV showed no statistically significant differences in terms of mortality (relative risk [RR] 0.61, 95% CI 0.32-1.14, P=0.12), safety composite end point (RR 0.85, 95% CI 0.62-1.18, P=0.34), moderate to severe paravalvular leaks (RR 0.68, 95% CI 0.23-1.99, P=0.48), need for postdilation (RR 0.86, 95% CI 0.66-1.13, P=0.58), stroke and/or transient ischemic attack (RR 0.72, 95% CI 0.30-1.71, P=0.45), and permanent pacemaker implantation (RR 0.80, 95% CI 0.49-1.30, P=0.37). CONCLUSIONS: Our analysis suggests that TAVI procedures with or without preimplantation BAV were associated with similar outcomes for a number of clinically relevant end points. Further studies including a large number of patients are needed to ascertain the impact of TAVI without preimplantation BAV as a standard practice.

Objective. Current methods for early identification of cerebral white matter injury in the premature infant at the bedside are inadequate. This study investigated the utility of advanced spectral analysis of the neonatal electroencephalogram (EEG) in the early diagnosis of white matter injury in the premature infant. The critical measurement used, suggested largely by previous studies in animal models, was the spectral edge frequency (SEF), calculated here as the frequency below which 90% of the power in the EEG exists. Methods. Fifty-nine very low birth weight infants (87% of eligible infants) had electrodes placed over the central and parietal regions (C3, P3, C4, and P4 sites according to the 10-20 international system) for the collection of EEG amplitude, intensity, and SEF. All averaged signals were analyzed off-line using software (Chart Analyzer; BrainZ Instruments, Auckland, NZ). All infants had a magnetic resonance imaging scan at term to identify the presence and severity of white matter injury. Results. There was no significant difference between conventional EEG amplitude and intensity for infants with or without evidence of white matter injury. However, premature infants with increasingly severe white matter injury had progressively lower SEFs compared with infants who did not exhibit white matter injury. Conclusions. These data suggest that SEF-based measures are useful for defining the presence and severity of white matter injury at the bedside. Pediatrics 2003;111: 27-33; white matter injury, prematurity, very low birth weight infant, electroencephalography, spectral analysis., Early identification of cerebral white matter injury in the premature infant at the bedside is imperfect. An ideal diagnostic tool for the detection of white matter injury should be able [...]

Cooling of the fetal scalp may reduce the brain damage associated with impaired cerebral blood flow in hypoxic-ischemic encephalopathy. Researchers attached cooling coils around the heads of fetal sheep and compared cerebral hypothermia with no treatment following carotid artery occlusion to deprive the brain of oxygen. Fetal sheep treated with cerebral hypothermia 5.5 hours after a 30-minute ischemic event developed less neuronal damage and recovered more electroencephalographic activity, compared to fetuses not cooled after blood flow to the brain was impeded., Objective. Cerebral hypothermia has been shown to reduce damage from experimental hy-poxia-ischemia if started shortly after reperfusion. However, in the newborn infant it may not be feasible to determine prognosis so soon after exposure to asphyxia. The aim of this study was to determine whether head cooling, delayed until shortly before the onset of postasphyxial seizure activity, is neuroprotective. Methods. Unanesthetized near-term fetal sheep in utero were subjected to 30 minutes of cerebral ischemia. Later, at 5.5 hours, they were randomized to either cooling (n = 7) or sham cooling (n = 10) for 72 hours. Intrauterine cooling was induced by circulating cold water through a coil around the fetal head. The water temperature was titrated to reduce fetal extradural temperature from 39.1 [+ or -] 0.1 [degrees] C to between 30 [degrees] C and 33 [degrees] C, while maintaining esophageal temperature [is greater than] 37 [degrees] C. Results. Cerebral cooling suppressed the secondary rise in cortical impedance (a measure of cytotoxic edema), but did not prevent delayed seizures, 8 to 30 hours after ischemia. Transient metabolic changes including increased plasma lactate and glucose levels were seen with a moderate sustained rise in blood pressure. This severe cerebral insult resulted in depressed residual parietal electroencephalographic activity after 5 days recovery (-14.2 [+ or -] 1.5 decibels), associated with a watershed distribution of neuronal loss (eg, 94 [+ or -] 4% in parasagittal cortex and 77 [+ or -] 4% in the lateral cortex). Hypothermia was associated with better recovery of electroencephalographic activity (-8.9% [+ or -] 1.8 decibels) and substantially reduced neuronal loss in the parasagittal cortex (46 [+ or -] 13%), the lateral cortex (9 [+ or -] 4%), and other regions except the cornu ammonis sectors 1 and 2 of the hippocampus. Conclusions. Delayed selective head cooling begun before the onset of postischemic seizures and continued for 3 days may have potential to significantly improve the outcome of moderate to severe hypoxic-ischemic encephalopathy. hypothermia-induced, cerebral ischemia therapy, hypoxic-ischemic encephalopathy, fetal monitoring, fetal lamb., ABBREVIATIONS. EEG, electroencephalograph; Pa[O.sub.2], arterial partial pressure of oxygen; dB, decibel; CaBF, carotid blood flow; ANOVA, analysis of variance; MAP, mean arterial blood pressure; ATP, adenosine triphosphate. There is now [...]

The natriuretic peptide (NP)-guanylyl cyclase receptor (GCR) binding inhibitor HS-142-1 was employed in examining how spiny dogfish shark rectal gland salt secretion is affected by C-type NP-GCR. HS-142-1 was found to stem the rise of salt secretion in explanted rectal glands perfused with blood taken from donor sharks. Results suggest that C-type NP inhibits rectal gland chloride secretion through guanylyl cyclase-linked receptors.

Receptors for the C-type natriuretic peptide (CNP) was demonstrated in cell membrane preparations from the rectal gland of the shark, Squalus acanthias. Competitive binding with rat atrial natriuretic peptide (rANP) reveal the presence of two classes of receptors depending on rANP affinity. CNP binding activated guanylate cyclase activity. The use of other ligands and modified CNPdid not elicit the same response suggesting that the receptors are highly specific for CNP.

Fetal heart rate variability (FHRV) is a key index of antenatal and intrapartum fetal well-being. FHRV is well established to be mediated by both arms of the autonomic nervous system, but it remains unknown whether higher centers in the forebrain contribute to FHRV. We tested the hypothesis that selective forebrain ischemia would impair the generation of FHRV. Sixteen chronically instrumented near-term fetal sheep were subjected to either forebrain ischemia induced by bilateral carotid occlusion or sham-ischemia for 30 min. Time, frequency, and nonlinear measures of FHRV were assessed during and for seven days after ischemia. Ischemia was associated with profound suppression of electroencephalographic (EEG) power, which remained suppressed throughout the recovery period (P < 0.001). During the first 5 min of ischemia, multiple time and frequency domain measures were increased (all P < 0.05) before returning back to sham levels. A delayed increase in sample entropy was observed during ischemia (P < 0.05). For the first 3 h after ischemia, there was moderate suppression of two measures of FHRV (very-low frequency power and the standard deviation of RR-intervals, both P < 0.05) and increased sample entropy (P < 0.05). Thereafter, all measures of FHRV returned to control levels. In conclusion, profound forebrain ischemia sufficient to lead to severe neural injury had only transient effect on multiple measures of FHRV. These findings suggest that the forebrain makes a limited contribution to FHRV. FHRV therefore primarily originates in the hindbrain and is unlikely to provide meaningful information on forebrain neurodevelopment or metabolism. [ABSTRACT FROM AUTHOR]

Objective: Existing clinical prediction models (CPM) for short-term mortality after transcatheter aortic valve implantation (TAVI) have limited applicability in the UK due to moderate predictive performance and inconsistent recording practices across registries. The aim of this study was to derive a UK-TAVI CPM to predict 30-day mortality risk for benchmarking purposes.Methods: A two-step modelling strategy was undertaken: first, data from the UK-TAVI Registry between 2009 and 2014 were used to develop a multivariable logistic regression CPM using backwards stepwise regression. Second, model-updating techniques were applied using the 2013-2014 data, thereby leveraging new approaches to include frailty and to ensure the model was reflective of contemporary practice. Internal validation was performed by bootstrapping to estimate in-sample optimism-corrected performance.Results: Between 2009 and 2014, up to 6339 patients were included across 34 centres in the UK-TAVI Registry (mean age, 81.3; 2927 female (46.2%)). The observed 30-day mortality rate was 5.14%. The final UK-TAVI CPM included 15 risk factors, which included two variables associated with frailty. After correction for in-sample optimism, the model was well calibrated, with a calibration intercept of 0.02 (95% CI -0.17 to 0.20) and calibration slope of 0.79 (95% CI 0.55 to 1.03). The area under the receiver operating characteristic curve, after adjustment for in-sample optimism, was 0.66.Conclusion: The UK-TAVI CPM demonstrated strong calibration and moderate discrimination in UK-TAVI patients. This model shows potential for benchmarking, but even the inclusion of frailty did not overcome the need for more wide-ranging data and other outcomes might usefully be explored. [ABSTRACT FROM AUTHOR]