Short-lasting, Unilateral, Neuralgiform Headache Attacks with Conjunctival Injection and Tearing (SUNCT Syndrome): IV. Respiratory sinus arrhythmia during and outside paroxysms

SUNCT is a headache syndrome characterized by short-lasting (usually 15-120 sec), unilateral head pain paroxysms localized in the peri-ocular area, accompanied by conjunctival injection, lacrimation, nasal stuffiness, rhinorrhea, and subclinical forehead sweating, all on the symptomatic side. A relative bradycardia seems to be an integral part of the paroxysm; a parasympathetic stimulation could theoretically be the causative factor for the bradycardia. In 3 SUNCT patients, vagal nerve function (E:I ratio) has been monitored outside and during pain paroxysms, while 3 other patients could be studied in the attack-free period only. E:I ratio is obtainable in the course of a maximally deep breath and represents the ratio of the longest R-R interval during a 5 sec long expiration to the shortest R-R interval during a 5 sec long expiration. The mean E:I ratio of SUNCT patients outside paroxysms was significantly higher than the mean E:I ratio in an aged-matched control group. The E:I ratio was, however, significantly decreased during paroxysms in comparison with ratios obtained outside the pain paroxysms. After 0.6 mg atropine administration s.c. to one of the patients in the symptomatic phase, the heart rate increased, and the relative bradycardia during headache paroxysm was diminished (but not completely abolished). The E:I ratio was lowered but it was still slightly larger outside than during attacks. The reason for the abrupt and seemingly clear attack-related decrement in E:I ratio together with the previously described relative bradycardia remains enigmatic, however the possibility of increased parasympathetic tone cannot be excluded.     

Acute pericarditis presenting with sinus bradycardia: A case report

Acute pericarditis is almost invariably associated with sinus tachycardia. Recent-onset chest pain in the presence of (sinus) bradycardia is considered to be associated with an acute ischemic syndrome rather than acute pericarditis. This report describes a patient with acute pericarditis initially presenting with sinus bradycardia, probably due to a vasovagal response to (chest) pain.     

Severe Sinus Bradycardia after Initiation of Bupropion Therapy: A Probable Drug-Drug Interaction with Metoprolol

Bupropion is an increasingly prescribed agent to aid in smoking cessation. However it has important drug-drug interactions related to the cytochrome P450 system. One of these is its inhibition of the metabolism of the commonly used beta-blocker, metoprolol. The authors describe a case of severe bradycardia related to the addition of bupropion to the medical regimen of a patient on metoprolol.     

Delivery of Noncommitted Shocks for Nonsustained Ventricular Arrhythmias by a New Implantable Cardioverter Defibrillator with Abortive Shock Capability

Shock Delivery Despite Abortive Shock Capability. Introduction: To describe the delivery of noncommitted implantable cardioverter defibrillator (ICD) shocks despite self-termination of ventricular arrhythmias. Abortive shock capability should eliminate the delivery of shocks for self-terminating ventricular arrhythmias. The delivery of noncommitted shocks despite abortive shock capability is, therefore, unexpected and previously unreported.
Methods and Results: Among 118 patients who received the Transvene nonthoracotomy lead system and the Jewel ICD (model 7219D), three patients (1.7%) experienced spurious, noncommitted shocks for self-terminating arrhythmias. Only one detection zone (i.e., ventricular fibrillation) had been programmed in the defibrillator in each patient. In all three patients, the ventricular arrhythmias self-terminated during the charging period. One patient received seven shocks during periods of asystole, and the other two patients received one shock each. Two different mechanisms for shock delivery in this setting were identified: one occurring in the absence of electrical activity at the end of the bradycardia escape interval (i.e., associated with bradyarrhytbmias), and the other when two sensed electrical events (i.e., escape beats) occurred during the so-called "synchronization" window of the defibrillator.
Conclusions: In rare patients with the Jewel defibrillator, shocks may be delivered for self-terminating arrhythmias despite abortive shock capability. Patients who are dependent upon pacing from their implanted defibrillator are at particular risk for shock in the aftermath of self-terminating ventricular arrhythmias. Defibrillator programming strategies aimed at eliminating or diminishing the incidence of this problem are discussed.     

Precursors of cardiorespiratory events in infants detected by home memory monitor

In 1,079 infants monitored for >700,000 hr at home for apnea or bradycardia, we found an association between infants having multiple events exceeding conventional or a priori defined more extreme thresholds and less favorable developmental outcome at 1 year of age than infants with few or no events. If it is necessary to prevent such events to minimize risk for developmental morbidity, there is reason to determine whether there are disturbances in advance of the apnea or bradycardia that herald their onset. In the 85 infants with at least 1 extreme event and 1 conventional event, we hypothesized that apnea and bradycardia do not occur de novo but rather are preceded by cardiorespiratory and hemoglobin O2 saturation changes. We compared recorded time intervals preceding these events, and we analyzed three preceding time intervals for each conventional and extreme event, and each non-event recording: Time-2 hr: up to 2 hr before; Time-1 hr: up to 1 hr before; and Time-75 sec: the 75 sec immediately preceding each event. O2 saturation progressively decreased preceding both conventional and extreme events, and progressive increases occurred in heart and breathing rate variability. Duration of respiratory pauses and of periodic breathing progressively increased preceding conventional events, respiratory rate variability increased immediately preceding conventional events and at 1 hr preceding extreme events, and O2 saturation decreased immediately preceding both conventional and extreme events. Thus, conventional and extreme events do not occur de novo but rather are preceded by autonomic instability of the cardiorespiratory system.     

Role of vagal activity on bradicardic and hypotensive effects of caffeic acid phenethyl ester (CAPE)

Caffeic acid phenethyl ester (CAPE) is a phenolic active component of propolis of honeybee hives and reduces heart rate and blood pressure in rats. The objective of this study was to investigate the role of vagal activity and atropine blockage on the bradycardic and hypotensive effects of CAPE in rats. The rats were divided into five groups (n=8). Saline and vehicle (10% ethanol) of CAPE were given to the first and second groups, respectively. Group 3 was treated with 5 mg/kg CAPE. Group 4 bivagotomized and treated with 5 mg/kg CAPE. Group 5 treated with atropine (5 μg/μL/min) continuously and treated with CAPE. The electrophysiological monitoring was done for each experiment under urethane anaesthetize. As a result, CAPE caused intense and transient bradycardia and hypotension. Vagotomy completely abolished bradycardia occurred via CAPE injection; however atropine attenuated bradycardic effects of CAPE. On the other hand, hypotensive effect of CAPE was affected from neither bilateral vagotomy nor atropine treatment. It was thought that CAPE may exert its effects on heart rate via a central parasympathetic control mechanism, but not on central parasympathetic blood pressure control system. This study was partly presented in The Experimental Biology 2005 Annual Meeting and the XXXV International Congress of Physiological Sciences in San Diego, CA, March 31–April 6, 2005.     

心脏临时起搏器在颅外颈动脉支架置入术中的应用观察

目的 观察心脏临时起搏器在颅外颈动脉支架围手术期防治血流动力学紊乱的有效性、安全性.方法 41例行颅外颈动脉支架术高危患者,共置入颈动脉支架47枚,术前经左侧股静脉安置心脏临时起搏器,起搏心率设定为60次/min,术中术后监测患者症状、血压心率变化、起搏器工作情况.结果 进行了球囊预扩张的25处颈动脉病变起搏器全部启动,25例患者出现一过性起搏器工作,持续工作最长时间1 d,1例伴发症状性低血压,低血压最长持续4 d.全部患者未出现相关并发症.结论 血流动力学紊乱是颅外颈动脉支架置入术围手术期常见的并发症,术前安置心脏临时起搏器可以快速、有效地纠正血流动力学紊乱,防止出现脑卒中等围手术期并发症,对于存在高危因素的患者,是值得推荐的方法.     

AUTONOMIC AND ENDOTHELIAL DYSFUNCTION IN EXPERIMENTAL DIABETES

The effect of streptozotocin induced diabetes on autonomic regulation of heart rate and endothelial function was examined in Sprague-Dawley rats. Weanling rats (3–4 weeks of age) of either sex were randomly assigned to a non-diabetic (male 5, female 6) or diabetic (male 4, female 5). Diabetes was induced with a single intraperitoneal (IP) injection of streptozotocin (STZ, 100 mg/kg). Non-diabetic rats received an IP injection of saline. Eight weeks after injection, rats were chronically instrumented with a left jugular venous catheter and a left carotid arterial catheter. After recovery (5 days) cardiac sympathetic tonus, parasympathetic tonus and intrinsic heart rate were determined. On an alternative day, the pressor response to nitric oxide synthase inhibition (NOS-X) was determined in areflexic rats. Cardiac sympathetic tonus (72 ± 13 vs. 41 ± 7), parasympathetic tonus (?51 ± 10 vs. ?22 ± 7), and intrinsic heart rate (368 ± 6 vs. 292 ± 9), were reduced in diabetic rats. Furthermore, diabetic rats had a smaller pressor response (Δ33 ± 7 vs. Δ66 ± 5) to NOS-X. These results document impaired autonomic control of heart rate and endothelial dysfunction in 8-week streptozotocin induced diabetic rats.     

The Significance of Bradycardia in Anorexia Nervosa

Anorexia nervosa (AN) is a life-threatening condition, with a significant risk for death, due to cardiovascular complications. It is characterized by abnormal eating behavior and has the highest mortality rate of all psychiatric disorders. It has been associated with bradycardia (a heart rate [HR] of less than 60 beats per minute) (up to 95%), hypotension, mitral valve prolapse, and heart failure. The diagnosis of AN can be elusive, and more than half of all cases are undetected. The purpose of this study was to raise and improve awareness to the possible diagnosis of AN in adolescent and young adult patients with weight loss displaying bradycardia and new cardiac disorders. Clinical characteristics, HR, and electrocardiographic data of 23 consecutive patients (20 females) with AN and of 10 young adults (8 females) without AN, between the years 2006 and 2009, were recorded and summarized. At presentation 16/23 (69.6%) showed HR < 50 bpm. The mean lowest HR of all patients was 44 ± 6 (range 26 to 68) bpm. No patient needed pacemaker therapy. Bradycardia in young adults, especially females with weight loss, should raise the possible diagnosis of AN, so it can be treated early in-time, and thus prevent premature death.