- Cardiac rhythm management devices [Journal Article]
- AJAust J Gen Pract 2018; 47(5):264-271
- The last decade has seen ongoing evolution and use of cardiac rhythm management devices, including pacemakers, cardiac resynchronisation therapy, implantable cardioverter defibrillators and loop reco...
The last decade has seen ongoing evolution and use of cardiac rhythm management devices, including pacemakers, cardiac resynchronisation therapy, implantable cardioverter defibrillators and loop recorders. General practitioners are increasingly involved in follow-up and management of patients with these devices.
- Heart rate changes during positive pressure ventilation after asphyxia-induced bradycardia in a porcine model of neonatal resuscitation. [Journal Article]
- ADArch Dis Child Fetal Neonatal Ed 2018 May 19
- CONCLUSIONS: In contrast to NRP recommendation, adequate PPV does not increase HR within 15 s after ventilation in piglets with asphyxia-induced bradycardia.
- α2 receptors in the lateral parabrachial nucleus generates the pressor response of the cardiovascular chemoreflex, effects of GABAA receptor. [Journal Article]
- BRBrain Res Bull 2018 May 15
- The lateral parabrachial nucleus (LPBN) is a pontine area involved in cardiovascular chemoreflex. This study was performed to find the effects of reversible synaptic blockade of the LPBN on the chemo...
The lateral parabrachial nucleus (LPBN) is a pontine area involved in cardiovascular chemoreflex. This study was performed to find the effects of reversible synaptic blockade of the LPBN on the chemoreflex responses, and to find the roles of GABAA receptor and α2-adenoreceptor (α2-AR) in chemoreflex. It also aimed to seek possible interaction between GABA and noradrenergic systems of the LPBN in urethane-anesthetized male rats. Cardiovascular chemoreflex was activated by intravenous injection of potassium cyanide (KCN, 80 μg/kg). The cardiovascular responses of chemoreflex were evaluated before (control), 5 and 15 minutes after microinjection of each drug (100 nl) into the LPBN. Microinjections of cobalt chloride (5 mM), a reversible synaptic blocker, into the LPBN greatly attenuated the chemoreflex pressor and bradycardic responses indicating that the LPBN plays a main role in chemoreflex. Local injection of yohimbine (10 nmol), an α2-AR antagonist, attenuated the pressor response with no effect on bradycardic response, suggesting that α2-adrenoreceptors are involved in producing the pressor response of the chemoreflex. Microinjection of bicuculline methiodide (BMI, 100 pmol), a GABAA antagonist, into the LPBN augmented the pressor response and attenuated the bradycardic response, indicating that GABA inhibits the sympathetic output to the heart and vasculature. Sequential injection of yohimbine and BMI had no significant effect on the pressor response but attenuated the bradycardia. In conclusion, the LPBN is essential for the chemoreflex responses. The pressor response of the chemoreflex, at least partly, is produced by α2- adenoreceptors. GABA in the LPBN inhibits the cardiovascular system. Finally, there is no interaction between GABAergic and adrenergic neurons of the LPBN in producing the cardiovascular chemoreflex.
- Drivers of the dive response in pinnipeds; apnea, submergence or temperature? [Journal Article]
- JEJ Exp Biol 2018 May 17
- Long and deep dives in marine mammals are enabled by high mass-specific oxygen stores and the dive response (DR), which reduces oxygen consumption in concert with increased peripheral vasoconstrictio...
Long and deep dives in marine mammals are enabled by high mass-specific oxygen stores and the dive response (DR), which reduces oxygen consumption in concert with increased peripheral vasoconstriction and a lowered heart rate during dives. Diving heart rates of pinnipeds are highly variable and modulated by many factors, such as breath holding (apnea), pressure, swimming activity, temperature, and even cognitive control. However, the individual effects of these factors on diving heart rate are poorly understood due to the difficulty of parsing their relative contributions in diving pinnipeds. Here, we examined the effects of apnea and external sensory inputs as autonomic drivers of bradycardia. Specifically, we hypothesized that 1) water stimulation of facial receptors would-as is the case for terrestrial mammals-enhance the dive response, 2) increasing the facial area stimulated would lead to a more intense bradycardia, and 3) cold water would elicit a more pronounced bradycardia than warm water. Three harbor seals (Phoca vitulina) and a California sea lion (Zalophus californianus) were trained to breath-hold in air and with their heads submerged in a basin with variable water level and temperature. We show that bradycardia occurs during apnea without immersion. We also demonstrate that bradycardia is strengthened with both increasing area of facial submersion and colder water. Thus, we conclude that initiation of the DR in pinnipeds is more strongly related to breath holding than in terrestrial mammals, but the degree of the DR is potentiated autonomically via stimulation of facial mechano- and thermoreceptors upon submergence.
- Clinical efficacy of xenon versus propofol: A systematic review and meta-analysis. [Journal Article]
- MMedicine (Baltimore) 2018; 97(20):e10758
- CONCLUSIONS: In this meta-analysis of randomized controlled trials, we found that xenon treatment resulted in a higher MAP, a lower HR, and a smaller BIS index than treatment with propofol.
- Carotid Stenting for Treatment of Symptomatic Carotid Webs: A Single-Center Case Series. [Journal Article]
- INInterv Neurol 2018; 7(5):233-240
- CONCLUSIONS: Stent placement for treatment of carotid webs can be performed safely. Further studies are needed to confirm our findings.
- Gastrocardiac syndrome: A forgotten entity. [Journal Article]
- AJAm J Emerg Med 2018 May 09
- Symptomatic bradycardia due to gastric distension is a rarely reported entity in the field of medicine. The mechanism of gastrointestinal distention that contributes to bradycardia is complex. A 75-y...
Symptomatic bradycardia due to gastric distension is a rarely reported entity in the field of medicine. The mechanism of gastrointestinal distention that contributes to bradycardia is complex. A 75-year-old female with recurrent episodes of dizziness in the setting of gastric distension was found to have severe sinus bradycardia which resolved upon resolution of gastric distension. No structural or functional abnormality of heart was found. The patient was treated with permanent pacemaker implantation due to recurrent episodes of dizziness in the setting of sinus bradycardia.
- The Leadless Cardiac Pacemaker: Conductive Communication. [Journal Article]
- JCJACC Clin Electrophysiol 2015; 1(4):335-336
- StatPearls [BOOK]
- BOOKStatPearls Publishing: Treasure Island (FL)
- Alpha-adrenergic agonist toxicity is due to a broad group of pharmaceutical agents known as alpha agonists, which can be further broken down into central alpha-2 agonists and peripheral alpha-1 agoni...
Alpha-adrenergic agonist toxicity is due to a broad group of pharmaceutical agents known as alpha agonists, which can be further broken down into central alpha-2 agonists and peripheral alpha-1 agonists. Central alpha-2 agonists include clonidine, guanfacine, tizanidine, guanabenz, and methyldopa. Peripheral alpha-1 agonists include imidazoline, oxymetazoline, tetrahydrozoline, and naphazoline. Mainly there are 2 alpha receptors of pharmacological significance – central alpha-2 and peripheral alpha-1 adrenergic receptors. Stimulation of central alpha-2 receptors causes decreased secretion of catecholamines through a negative feedback mechanism. Stimulation of peripheral alpha-1 receptors primarily increases blood pressure via induced vasoconstriction. Alpha-adrenergic agonist toxicity is of primary concern with alpha-2 adrenergic agonist xenobiotics through the resulting depletion of catecholamines associated with these agents; however, there are many topical alpha-1 agonists that when misused cause similar toxicity. Toxicity is encountered in various populations, particularly in children and adolescents, due to the growing use of these agents. Toxicity is associated with a compilation of symptoms, including central nervous system depression, bradycardia, and hypotension. Alpha-adrenergic toxicity is often very responsive to supportive care, including intravenous fluid administration, airway monitoring, and repletion of catecholamines as necessary via the use of vasopressor agents. There is no antidote approved for human use, and naloxone has no proven efficacy.
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- StatPearls [BOOK]
- BOOKStatPearls Publishing: Treasure Island (FL)
- The oculocardiac reflex (OCR), also known as the Aschner reflex or trigeminovagal reflex (TVR), was first described in 1908 as a reduction in heart rate secondary to direct pressure placed on the eye...
The oculocardiac reflex (OCR), also known as the Aschner reflex or trigeminovagal reflex (TVR), was first described in 1908 as a reduction in heart rate secondary to direct pressure placed on the eyeball. It is defined by a decrease in heart rate by greater than 20% following globe pressure or traction of the extraocular muscles. The reflex most commonly results in sinus bradycardia. However, it also has a reported association with reduced arterial pressure, arrhythmia, asystole, and even cardiac arrest. This reflex has most notably been depicted during ophthalmologic procedures, more specifically during strabismus surgery; however, it also may be activated by facial trauma, regional anesthetic nerve blocks, and during mechanical stimulation. The incidence of the oculocardiac reflex is reported to be anywhere from 14% to 90% and decreases with age, meaning pediatric patients are most at risk. Pediatric patients are also more susceptible to the detrimental consequences of this reflex secondary to having a greater dependency on heart rate to maintain cardiac output. The wide range of incidence and the severity of OCR is reportedly attributed to the effects of hypoxia, hypercarbia, acidosis, and the anesthetic agents used during surgery.