Vagal nerve stimulation: surgical technique
Hans O Lüders in Deep Brain Stimulation and Epilepsy, 2020
The neurologist or intra-operative neuro-physiologist may assist you at this stage. The computer and hand-held wand are powered up. Make sure the batteries in the hand-held wand are new. Place the hand-held wand in a sterile drape and place it over the generator in the surgical field (Figure 19.6). During this programming, lead impedance and all connections are tested to verify integrity of the system. A one minute lead test is then performed with a stimulus delivered at 20 Hz frequency, output current of 1 mA, and a pulse width of 500 microseconds. During this test, the patient’s vital signs and electrocardiogram (ECG) are monitored for bradycardia. Some centers will then turn on the system at the lowest setting, while most prefer to wait one or two weeks before initiating stimulation therapy.
Bioelectric and Biomagnetic Signal Analysis
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam in Introduction to Computational Health Informatics, 2019
Arrhythmia is a common problem in old age. The heartbeat becomes irregular in arrhythmia. Heartbeat can either slow down or speed up. Bradycardia is a subclass of arrhythmia when the rate of heartbeats slows down. Tachycardia is another subclass of arrhythmia when the heartbeat speeds up. Tachycardia is divided into two subclasses: 1) supraventricular arrhythmia caused by abnormalities in the atria and 2) ventricular arrhythmia caused by abnormalities in the ventricles. Three major problems cause irregular heartbeats: 1) abnormality in ion-channels of heart cells that disturb the depolarization cycle of the SA-node and/or heart-cells; 2) change in the origin of the electrical activity in the heart and 3) fibrillation of heart-muscles. Fibrillation causes: 1) random alignment in heart-muscles disorienting the regular electrical pattern and 2) fibrous tissues that become an alternate source of irregular electrical activities in addition to the SA-node.
Grayanotoxins
Dongyou Liu in Handbook of Foodborne Diseases, 2018
Sinus bradycardia and conduction defects usually respond to atropine therapy. Recovery in these intoxication cases usually occurs within 24 hours. However, in some cases of severe poisoning, patients require care and monitoring in coronary intensive care units for several days. A pacemaker should be used if bradycardia is not responsive to atropine treatment.49 In cases of hypotension not responsive to atropine and a cardiac pacemaker, fluid replacement therapy and respiratory support may be necessary. For such cases, intravenous fluids are used to treat the initial hypotension and vasopressors should be considered for profound hypotension.49 For treatment of ventricular arrhythmias, amiodarone is preferred to other drugs, including flecainide, procainamide, and lidocaine. Magnesium has been found to suppress polymorphic ventricular tachycardia.
Current and emerging treatment options for Angelman syndrome
Published in Expert Review of Neurotherapeutics, 2023
Christopher J. Keary, Christopher J. McDougle
For aggression or SIB that does not respond to behavioral strategies, pharmacotherapy may be considered (Figure 1). A published case series described the use of buspirone, a serotonin (5-HT)1A receptor partial agonist, in patients with AS who had behaviors concerning for anxiety, including aggression and SIB [54]. The three patients described showed improvement in aggression, SIB, vomiting, and specific fears (crowds) and tolerated the medication well. Buspirone carries an indication for the treatment of generalized anxiety disorder in adults from the FDA, though it is most commonly used to treat anxiety in children due to a mild side effect profile [55]. Clonazepam and short-term use of lorazepam have FDA indications for treatment of panic disorder and anxiety disorders, respectively. While there are no trials of these medications yet for treatment of aggression or SIB in AS, they are commonly tried in clinical practice and may have the dual benefit of reducing anxiety and seizure risk. Potential side effects of these medications include sedation, weakness, dizziness/ataxia, and rare risks of hypotension or paradoxical reactions of hyperexcitability. Finally, the beta-adrenergic receptor blocking agent propranolol was found to reduce aggression in 85% of patients with ASD in a retrospective chart review of 46 patients 8–32-year old [56] and may also be considered in AS. Side effects may include fatigue, dizziness, bradycardia, and hypotension. In some cases, propranolol can cause bronchospasm in those with asthma and can worsen cardiac function in those with congestive heart failure.
Derivation and internal validation of a clinical prediction score to predict major effect or death in acute metamfetamine toxicity
Published in Clinical Toxicology, 2023
Rex Pui Kin Lam, Chi Keung Chan, Man Li Tse, Eric Ho Yin Lau, Zonglin Dai, Matthew Sik Hon Tsui, Timothy Hudson Rainer
Unlike other early warning scores, we did not divide individual physiological parameters, such as pulse rate, into different risk bands, in which extreme values at both ends of the spectrum are generally given a higher score [12–16]. We are aware that some physiological parameters might not have a linear association with poor clinical outcomes. For instance, patients with severe bradycardia and tachycardia are both at risk of major effect or death. However, using the risk-band approach warrants the use of a scoring chart or software in score calculation, adding to the cognitive load of the users. We dichotomized physiological parameters for ease of use and weighed individual parameters with whole numbers to simplify the calculation. For parameters such as pulse rate, mean arterial pressure should be low if the bradycardia is severe enough to cause hemodynamic instability. Despite being a simpler scoring system based on dichotomized variables, the MASCOT score still performed well compared with existing early warning scores within the validation cohort, in which the pattern of drug use and occurrence of major effect or death were different from the derivation cohort. This indicates that model overfitting is less likely and the score is robust in different populations. Although the point estimate of the AUROC of the MASCOT score was lower than that of the MEWS, MEWS with GCS, and NEWS2, their 95% CIs overlapped considerably, making it difficult to confirm the superiority of one scoring system over the others.
Tests for the identification of reflex syncope mechanism
Published in Expert Review of Medical Devices, 2023
Michele Brignole, Giulia Rivasi, Artur Fedorowski, Marcus Ståhlberg, Antonella Groppelli, Andrea Ungar
Identifying the mechanism of reflex syncope is the essential prerequisite for an effective personalized therapy. Indeed, the choice of appropriate therapy and its efficacy are largely determined by the mechanism of syncope rather than its etiology or clinical presentation [1]. While in most patients the etiological diagnosis of vasovagal and other forms of reflex syncope can be achieved through accurate history taking and exclusion of competitive causes, the diagnosis of the underlying mechanism requires the use of diagnostic tests aimed to document the causal link between a specific hemodynamic mechanism and loss of consciousness. The possible hemodynamic mechanisms underlying reflex syncope include hypotension and asystole/bradycardia, corresponding to two different hemodynamic phenotypes, i.e. the hypotensive and bradycardic phenotype. The choice of therapy – counteracting hypotension or bradycardia – depends on the given phenotype.
Related Knowledge Centers
- Dizziness
- Fatigue
- Heart Rate
- Perspiration
- Syncope
- Vagal Tone
- Sinus Bradycardia
- Electrocardiography
- Weakness
- Athletic Heart Syndrome