Anti-stroke prophylaxis--the ethics of collateral damage

Prophylactic anticoagulation therapy with agents such as dabigatran etexilate (as an alternative to warfarin) promises substantial benefits to both patients and monitoring physicians in the treatment of those at high risk of stroke from atrial fibrillation. Such treatment has, however, one potentially lethal consequence. There is, as yet, no easily administered rapid means of reversal in instances of acute surgical emergency. The problems that may then be encountered in neurosurgical practice are discussed.     

Complementary effect of surgical resection and responsive brain stimulation in the treatment of bitemporal lobe epilepsy: a case report

We report a 39-year-old man with bilateral mesial temporal lobe epilepsy. He was implanted with a responsive brain stimulator (RNS System) with two depth electrodes placed in the bimesial temporal structures. After the implantation, his seizure frequency decreased by up to 50%. Electrocorticogram recorded by the RNS device revealed the right-sided predominance of seizure onset. He underwent a right temporal lobectomy, and his seizure significantly improved. After the RNS System was restarted 107 days after the temporal lobectomy, he has been seizure free for more than 1.5 years. However, the implanted device continued to record residual ictal activities at the posterior aspect of the right hippocampus and delivered electrical stimuli to suppress the seizure activities. Our report indicates the importance of electrocorticographic recordings by the RNS System to modify the treatment strategy and the complementary effect of surgical resection and brain stimulation in the treatment of epilepsy.     

Rapid homeostatic plasticity of intrinsic excitability in a central pattern generator network stabilizes functional neural network output

Neurons and networks undergo a process of homeostatic plasticity that stabilizes output by integrating activity levels with network and cellular properties to counter longer-term perturbations. Here we describe a rapid compensatory interaction among a pair of potassium currents, I(A) and I(KCa), that stabilizes both intrinsic excitability and network function in the cardiac ganglion of the crab, Cancer borealis. We determined that mRNA levels in single identified neurons for the channels which encode I(A) and I(KCa) are positively correlated, yet the ionic currents themselves are negatively correlated, across a population of motor neurons. We then determined that these currents are functionally coupled; decreasing levels of either current within a neuron causes a rapid increase in the other. This functional interdependence results in homeostatic stabilization of both the individual neuronal and the network output. Furthermore, these compensatory increases are mechanistically independent, suggesting robustness in the maintenance of neural network output that is critical for survival. Together, we generate a complete model for homeostatic plasticity from mRNA to network output where rapid post-translational compensatory mechanisms acting on a reservoir of channels proteins regulated at the level of gene expression provide homeostatic stabilization of both cellular and network activity.     

Classical response of antidromic atriofascicular tachycardia to premature atrial extrastimulus delivered during septal refractoriness

A 23‐year‐old gentleman presented with a history of palpitations. The 12‐lead electrocardiogram showed no manifest ventricular pre‐excitation. Echocardiogram was within normal limits. A retrograde study showed concentric activation of the atrium with decremental conduction. Atrial pacing from right atrial free wall showed progressive pre‐excitation. No anterograde nodal duality was documented.     

Response of narrow QRS tachycardia in a patient with surgical closure of atrial septal defect to atrial overdrive pacing: What is the mechanism?

A 57‐year old woman who had pericardial patch closure of ostium secundum atrial septal defect (ASD) at the age of 23 years presented with shortness of breath. Her echocardiogram showed no residual ASD, good biventricular function and normal pulmonary artery pressures.     

Outcomes of Transcatheter Aortic Valve Replacement in Mixed Aortic Valve Disease

ObjectivesThe aim of this study was to compare outcomes after transcatheter aortic valve replacement (TAVR) in patients with pure aortic stenosis (AS) (i.e., no or trivial associated aortic regurgitation [AR]) with those in patients with AS and mild or more severe AR (i.e., mixed aortic valve disease [MAVD]).BackgroundTAVR is indicated in treating patients with severe AS. Limited data exist regarding the outcomes of TAVR in patients with MAVD.MethodsA total of 1,133 patients who underwent TAVR between January 2014 and December 2017 were included. The primary outcome was all-cause mortality. The comparison was adjusted to account for post-TAVR AR development in both groups. The secondary outcomes included composite endpoints of early safety and clinical efficacy as specified in the Valve Academic Research Consortium-2 criteria. Variables were compared using Mann-Whitney, chi-square, and Fisher exact tests, while Kaplan-Meier analyses were used to compare survival.ResultsA total of 688 patients (61%) had MAVD (median age 83 years , 43% women). Among these, 17% developed mild, 2% moderate, and <1% severe post-TAVR AR. Overall, patients with MAVD had better survival compared with patients with pure AS (p = 0.03). Among patients who developed post-TAVR AR, those in the MAVD group had better survival (p = 0.04). In contrast, in patients who did not develop post-TAVR AR, pre-TAVR AR did not improve survival (p = 0.11).ConclusionsPatients with MAVD who underwent TAVR had better survival compared with patients with pure AS. This is explained by the better survival of patients with MAVD who developed post-TAVR AR, likely due to left ventricular adaptation to AR.     

Complex decisions: correlates of injectable contraceptive discontinuation following HIV-1 seroconversion in an HIV prevention trial

Contraceptive adherence during acute and recent HIV-1 infection is important to maternal and child health given the elevated risk of vertical HIV-1 transmission and additional complications of pregnancy. Injectable contraception (IC) is the most common non-barrier modern contraception method used in sub-Saharan Africa (SSA). Adherence to IC after HIV-1 seroconversion is not well understood. We examined factors associated with IC discontinuation among women in SSA diagnosed with HIV-1 infection while participating in a clinical trial of biomedical HIV-1 prevention. After diagnosis with HIV-1 infection in the VOICE trial, 255 women from South Africa, Uganda, and Zimbabwe enrolled in a longitudinal observational study (MTN-015). Contraceptive method was assessed at MTN-015 baseline and at 3, 12, and 24 months post-seroconversion. Correlates of IC discontinuation were examined by Cox proportional hazard modeling. IC use was reported at baseline by 78% of women enrolled (198/255), of which 92% (182/198) completed at least one follow-up visit. Two-thirds of women (66%, 121/182) continued on IC during the follow-up period (median 24 months). Lower rates of IC discontinuation were observed in women who reported having had at least one child (HR 0.39, 95% CI 0.20–0.82) or earning a personal income (HR 0.51, 95% CI 0.30–0.87) at baseline. These findings suggest that many women with HIV-1 infection face complex decision-making regarding family planning in the years that follow seroconversion and highlight that some women may discontinue IC use despite on-site provision of family planning services. Understanding the broader context of family planning choices in recently seroconverted women may be key to more effective linkages between family planning services and HIV-1 testing and care.