Increased expression of blood muscarinic receptors in patients with reflex syncope

Vasovagal syncope: An overview of pathophysiological mechanisms

Syncope is a short-term transient loss of consciousness, characterized by rapid onset and complete spontaneous recovery. According to the 2018 European Society of Cardiology guidelines, three different types of syncope have been identified. However, all forms of syncope share a common final pathophysiological event, global cerebral hypoperfusion, which results from the inability of the circulatory system to maintain blood pressure at the level required to efficiently supply blood to the brain. The vasovagal syncope (VVS) is the most common form of syncope. Although, VVS is generally harmless, its frequent occurrence can negatively affect quality of life and increase the risk of adverse events. The pathophysiological mechanisms underlying VVS remain obscure. The multifaceted nature of VVS presents a veritable challenge to understanding this condition and developing preventative strategies. Thus, the aim of this review was to discuss the factors contributing to the pathogenesis of VVS and provide guidance for future research.

Anticholinergic Medications and Parent-Reported Anticholinergic Symptoms in Neurologically Impaired Children

CONTEXT

Children with severe neurological impairment and polypharmacy are exposed to anticholinergic (AC) medications that may have anticholinergic side effects, but this is understudied. Anticholinergic Cognitive Burden (ACB) scores measure total anticholinergic burden for a medication regimen, and scores ≥3 have been associated with increased morbidity and mortality in adults.

OBJECTIVE

We assessed the relationship between ACB scores and parent-reported anticholinergic symptoms in children.

METHODS

Cross-sectional study of patients one to 18 years-old with ICD-defined severe neurological impairment and polypharmacy. At routine clinical visits, total ACB scores were computed for all medications. Parent-reported AC symptoms (constipation, drowsiness, difficulty concentrating, dry mouth, or urinary problems) were assessed. Multivariable logistic regression was used to test the association between total ACB scores ≥3 for scheduled medications and the presence of AC symptoms, adjusted for age and recent acute healthcare utilization.

RESULTS

Among 123 unique patients, 87% were prescribed AC medications. Common AC medication classes included: systemic antihistamines (64%), anxiolytics (53%), antidepressants (30%), H2 blockers (22%), and muscle relaxants (20%). Total ACB scores ≥3 were observed in 44% for scheduled medications and in 63% of patients for scheduled plus PRN medications. Total ACB scores ≥3 were significantly associated with an increased odds of ≥1 anticholinergic symptoms for scheduled medications (OR: 3.1; 95% CI: 1.4, 6.7) and for scheduled plus PRN medications (OR: 2.9; 95% CI: 1.3, 6.4).

CONCLUSION

If replicated in larger populations, the association between elevated total ACB scores and anticholinergic side effects in children should prompt clinicians to consider deprescribing potentially unneeded anticholinergic medications.

The pathophysiology of vasovagal syncope: Novel insights

The pathophysiology of vasovagal syncope (VVS) is reviewed, focusing on hemodynamic aspects. Much more is known about orthostatic than about emotional VVS, probably because the former can be studied using a tilt table test (TTT). Recent advances made it possible to quantify the relative contributions of the three factors that control blood pressure: heart rate (HR), stroke volume (SV) and total peripheral resistance (TPR). Orthostatic VVS starts with venous pooling, reflected in a decrease of SV. This is followed by cardioinhibition (CI), which is a decrease of HR that accelerates the ongoing decrease of BP, making the start of CI a literal as well as fundamental turning point. The role of hormonal and other humoral factors, respiration and of psychological influences is reviewed in short, leading to the conclusion that a multidisciplinary approach to the study of the pathophysiology of VVS may yield new insights.

A Step further-The Role of Trigeminocardiac Reflex in Therapeutic Implications: Hypothesis, Evidence, and Experimental Models

The trigeminocardiac reflex (TCR) is a well-recognized brainstem reflex that represents a unique interaction between the brain and the heart through the Vth and Xth cranial nerves and brainstem nuclei. The TCR has mainly been reported as an intraoperative phenomenon causing cardiovascular changes during skull-base surgeries. However, it is now appreciated that the TCR is implicated during non-neurosurgical procedures and in nonsurgical conditions, and its complex reflex pathways have been explored as potential therapeutic options in various neurological and cardiovascular diseases. This narrative review presents an in-depth overview of hypothetical and experimental models of the TCR phenomenon in relation to the Vth and Xth cranial nerves. In addition, primitive interactions between these 2 cranial nerves and their significance are highlighted. Finally, therapeutic models of the complex interactions of the TCR and areas for further research will be considered.