Syncope, seizure, or both? An unusual case of complete heart block

Syncope and epileptic seizures have common presenting features that make it difficult to determine if a patient's collapse is primarily cardiac or neurologic. The distinction is blurred further if epileptic neural activity provokes cardiac arrhythmias known to cause syncope. We present a case of convulsive movements, progressive atrioventricular block, and syncope in a patient known to have epilepsy. The history, serial electrocardiographic tracings, and other diagnostic tests strongly suggest the ictal bradycardia syndrome. The case illustrates interesting aspects of central autonomic function and the diagnostic and therapeutic dilemmas of evaluating and treating patients who present with this problem.     

Asymptomatic profound sinus bradycardia (heart rate ≤45) in non-small cell lung cancer patients treated with crizotinib

Crizotinib, a dual MET/ALK inhibitor, is now in advanced clinical development for the treatment of anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer (NSCLC). We have observed several patients who developed profound but asymptomatic sinus bradycardia (HR ≤45) during the course of crizotinib treatment. Herein, we describe the clinical characteristics of three separate patients enrolled in the A8081001 trial (NCT00585195) who developed asymptomatic profound sinus bradycardia with their accompanying electrocardiogram tracings.     

30例窦性心动过缓患者心率震荡分析

目的应用窦性心率震荡（heart rate turbulence,HRT）这一新的预测心脏性猝死方法,探讨窦性心动过缓患者的临床预后。方法30例窦性心动过缓患者接受动态心电图检查,窦性心率〈50次／分为入组条件。采集单发室性早搏的前2个窦性RR间期及后20个窦性RR间期,根据公式分别计算震荡初始（turbulence onset,TO）和震荡斜率（turbulence splope,TS）。结果30例窦性心动过缓患者的HRT均值TO：（1．03±0．97）％;TS：（3．87±1．93）ms／RR间期。提示本文30例窦性心动过缓患者室性早搏后初始窦性心率加速现象消失。结论窦性心率〈50次／分的心动过缓患者可能也是发生心脏性猝死的高危人群。     

Is Chronic Atrial Stimulation a Reliable Method for Single Chamber Pacing in Sick Sinus Syndrome?

To evaluate the feasibility of chronic atrial pacing (AAI) in sick sinus syndrome (SSS), 22 patients (pts) with bradytachycardia syndrome (BTS) and 17 patients with only bradyarrhythmias (BA) were studied on the incidence of supraventricular tachycardias (SVT) and occurring AV block. A scoring system based on symptoms of SVT was developed (grade 0–5). All patients had proven normal AV conduction before PM implantation. In the BTS-group, nine patients (41%) had symptomatic SVT at the end of follow-up (mean 53 months), despite drug therapy. These patients had a high SVT score on entry (mean 3.2). High degree AV block occurred in three patients. Although in the BA-group SVT arose in six patients (35%), there was only one symptomatic patient at the end of follow-up (mean 36 months). In this group, only one patient developed high degree AV block. Atrial stimulation should be considered as a reliable therapy in patients with SSS and low SVT score before PM implantation when normal AV conduction is present.     

Early adrenaline administration does not improve circulatory recovery during resuscitation from severe asphyxia in newborn piglets

Aim of the study

To investigate the effects of early intravenous adrenaline administration on circulatory recovery, cerebral reoxygenation, and plasma catecholamine concentrations, after severe asphyxia-induced bradycardia and hypotension.

Methods

One-day-old piglets were left in apnoea until heart rate and mean arterial pressure were less than 50 min⁻¹ and 25 mmHg, respectively. They randomly received adrenaline, 10 μg kg⁻¹ (n = 16) or placebo (n = 15) and were resuscitated with air ventilation and, when needed, closed-chest cardiac massage (CCCM). Eight not asphyxiated animals served as time controls.

Results

CCCM was required in 13 piglets given adrenaline and in 13 given placebo. Time to return of spontaneous circulation was: 72 (66–85) s vs. 77 (64–178) s [median (quartile range)] (p = 0.35). Time until cerebral regional oxygen saturation (CrSO₂) had increased to 30% was 86 (79–152) s vs. 126 (88–309) s (p = 0.30). The two groups did not differ significantly in CrSO₂, heart rate, arterial pressure, right common carotid artery blood flow, or number of survivors: 13 vs. 11 animals. Plasma concentration of adrenaline, 2.5 min after resuming ventilation, was 498 (268–868) nmol l⁻¹vs. 114 (80–306) nmol l⁻¹ (p = 0.01). Corresponding noradrenaline concentrations were 1799 (1058–4182) nmol l⁻¹vs. 1385 (696–3118) nmol l⁻¹ (ns). In the time controls, the concentrations were 0.4 (0.2–0.6) nmol l⁻¹ of adrenaline and 1.8 (1.3–2.4) nmol l⁻¹ of noradrenaline.

Conclusion

The high endogenous catecholamine levels, especially those of noradrenaline, may explain why early administered adrenaline did not significantly improve resuscitation outcome.     

加味麻黄附子细辛汤治疗窦性心动过缓临证体会

追溯麻黄附子细辛汤的组方背景,分析麻黄附子细辛汤的药物组成,论述麻黄附子细辛汤和窦性心动过缓之间的联系,介绍治疗窦性心动过缓的临床用药特点,指出窦性心动过缓的发病机制与心气、心阳亏虚紧密相关,明确气阳两虚、阴寒内盛的发病病机,治疗以益气温阳散寒为主要治则,用药在益气温阳药的基础上,酌加活血药、滋阴药,收效可观,并附典型病例1则。     

Atrial natriuretic factor (ANF 103–126) enhances volume- and pressor-induced heart rate response in the conscious rat

The reduction in blood pressure due to ANF(103–126) fails to elicit reflex cardioacceleration in the conscious rat. To examine baroreflex sensitivity, the effect of ANF(103–126) on the heart period (HP) response to rapid central volume expansion and to alterations in mean arterial pressure (MAP) induced by bolus injections of phenylephrine and sodium nitroprusside was assessed. ANF(103–126) significantly augmented the bradycardic response induced by acute volume expansion from 426 ± 21 to 391 ± 23 beats min^-1 versus 421 ± 23 to 405 ± 24 without ANF(103–126). Baroreflex sensitivity was defined by the ratio of the change in heart period to the maximal change in mean arterial pressure. The dose of ANF(103–126) utilized did not affect basal heart rate or the magnitude of the mean arterial pressure response to phenylephrine but did significantly enhance the nitroprusside-induced decrease in mean arterial pressure. Baroreceptor sensitivity to phenylephrine was significantly increased by ANF(103–126): 0.997 ± 0.07 (ms mmHg^-1) during ANF(103–126) vs 0.613 ± 0.08 during vehicle. The total duration of the heart rate response to phenylephrine was also prolonged. In contrast, ANF(103–126) did not alter the baroreceptor sensitivity (1.45 ± 0.3 vs 1.43 ± 0.2 ms mmHg^-1) or duration of heart rate response to nitroprusside. In the conscious rat, ANF(103–126) modifies the heart rate response to changes in mean arterial pressure and acute central volume expansion. This action appears to be dependent on stimulation of cardiac vagal afferents.     

Bradycardia as a side-effect to oxybuprocaine

Sinus bradycardia was observed as a side-effect to the use of 0.4% oxybuprocaine eye-drops in a 48-year-old man with acute conjunctivitis. Blood pressure was not measurable during the episode.     

Incidence of intra-operative bradycardiaComparison of atracurium and vecuronium in gynaecological surgery

Intra-operative bradycardia is one of the most common cardiac arrhythmias observed in clinical anaesthetic practice and can lead to a potentially dangerous outcome. In a randomised double-blind trial, 50 female patients undergoing elective abdominal hysterectomy were divided into two groups. Group I received atracurium and group II received vecuronium as a neuromuscular blocking agent in a balanced anaesthetic technique. The incidence of bradycardia was compared among the two groups. Bradycardia was defined as a heart rate of less than 60 beat.min⁻¹. A heart rate of less than 45 beat.min⁻¹ was labelled as severe bradycardia and symptomatic bradycardia was defined as bradycardia associated with hypotension. The two groups were similar in their demographic characteristics. The results showed that there was no statistically significant difference among the two groups regarding the incidence of simple bradycardia. However, the incidence of severe bradycardia or symptomatic bradycardia requiring treatment was significantly higher in the vecuronium group.