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1、Arrhythmias and Antidysrrhythmics (Antiarrhythmic Drugs) 心律失常与抗心律失常药,医学院药理学教研室,心音听诊,节律 rhythm 频率 rate (杂音 murmur) 当节律与频率发生改变 心律失常 cardiac arrhythmia 节律不齐： 频率变化：,期前收缩(早搏)premature beat,心动过缓 bradycardia, bradyarrhythmias,心动过速 tachycardia, tachyarrhythmias,A Case Study 拳头的力量-1,王女士今年68岁，吃了海产品后出现腹部疼痛、腹泻2
2、天。腹泻已有十余次，量较多，呈稀水样，伴恶心、呕吐。昨起发热，体温38.5 。急诊医生诊断王女士为急性胃肠炎，住急诊观察室。 医嘱暂禁食，并给予静脉注射庆大霉素、5%葡萄糖生理盐水1000mL、10%葡萄糖水1000mL。经过一个白天的治疗，患者吐泻逐渐减轻，体温下降，但王女士仍觉腹胀、乏力，没有胃口。 晚间接班值班医师查房见患者神智清楚，平卧于病床上休息，体温37.5，血压110/80 mmHg，心跳88次/min。 王女士以往有高血压病史，平素血压控制在140/90mmHg左右。,拳头的力量-2,值班医师为患者测定血压心率之后,转身将血压计放回诊疗台，准备做病情记录，突听王女士女儿尖声呼叫
3、：“我妈妈不好了！” 医生回头见患者神智丧失，两眼上翻，四肢呈强直性痉挛状态。 值班医师迅速拿起听诊器往患者胸前听诊，未闻及心音，迅即举起拳头就往患者胸部用力捶去 “为什么打我妈妈？！ ”患者女儿的抗议声未落，只见患者双眼睑翻了数次，然后缓缓睁开眼睛，恢复了神智，惊异地看着身边的女儿在哭泣，不知刚才发生了什么事情。,拳头的力量-3,即刻床旁心电图检查显示：窦性心律、多发室性早搏。同时立即抽血送检验，接心电监护，并开始静脉给予连续滴注利多卡因。3分钟后患者再次发作意识丧失一次，心电监护记录显示如图1所示。 图1 患者发作意识丧失前及意识丧失时的心电图 经胸外捶击无效后立即开始心外按压。,拳头的力
4、量-4,此时立即将备好的心电除颤器进行充电，接好电极立即行体外心脏电击，一次电击成功恢复窦性心律，心电图如图2所示。 图2 予以电击除颤前后的心电图,拳头的力量-5,心跳骤停抢救的过程中紧急抽血化验的结果回报：血钾为2.0 mmol/L，血糖5.9 mg/mL。于是开始静脉输液中加入氯化钾缓慢静脉滴注。患者此时呈昏睡状，血压95/75 mmHg，心跳96次/min，节律不齐。 除颤成功后给予患者使用冰帽，静脉输液中继续补充氯化钾,同时补充5%碳酸氢钠40mL，连续滴注利多卡因。 在接下来的治疗中，血压逐渐回升至130/85 mmHg，心跳75次/min。患者的血钾逐渐恢复至正常，心律失常逐渐减
5、少至消失。,疾病的发展过程与生理基础,低血钾致心肌自律性升高 心室复极不一微折返室颤,胃肠炎呕吐腹泻致胃肠大量失钾 补充不足不恰当,心脏泵功能丧失 全身供血停止 (心音消失),中枢神经系统缺血缺氧 意识丧失伴短暂抽搐,迅速复苏 抗心律失常 补钾 保护大脑 ,（10s）,最后诊断与处理,Cardiac arrest 心跳骤停cardiac resuscitation 心脏复苏 Ventricular fibrillation 室颤defibrillation 机械除颤，电除颤，药物除颤 Hypokalemia 低钾血症potassium administration 补充失钾（纠正诱发因素） A
6、cute GI infection 急性胃肠道感染、上吐下泻antibacterial therapy and maintenance of water and electrolytes homeostasis 抗感染（病因治疗） 维持水与电解质平衡 其他：补充水电解质的细节问题,大量葡萄糖进入细胞伴随着血钾进入细胞,上吐下泻补充葡萄糖与水电解质应记住补充钾,Cell,glucose,Na+,Na+,insulin,(细胞外)低血钾易导致室性心律失常,上吐下泻补充葡萄糖、水、电解质时应记住补充钾,Principles of Cardiac Electrophysiology 心肌细胞四大电生理
7、特性,Excitability兴奋性: action potential upon stimulation, which is related to threshold potential and resting potential level Automaticity自律性: ability to initiate own activity via spontaneous depolarization Conductivity传导性: ability to transmit impulses from cell to cell at appropriate rates, which is d
8、ependent on membrane responsiveness (relationship between Vmax of phase 0 and membrane potential level) Refractoriness 不应性与不应期: ability to resist to stimulation during repolarization. The time between phase 0 and sufficient recovery of Na+ channels in phase 3 to permit a propagated response to exter
9、nal stimulus is the refractory period.,心脏的起搏传导系统与工作心肌,心电图,Sino-atrial,Atrial-ventricular,Action potential of ventricle and ion channel 心室肌动作电位及离子通道,Fast response,Outside,Inside,Channels current,Pacemaker potential and ion channel 起搏心肌动作电位及离子通道,Slow response,Outside,Inside,-45mV,Background inward Na+
10、 currents,Na+,Action potential, ion channels and myocardial refractory period 动作电位与离子通道、心室肌不应期,A new action potential cannot occur in an excitable fiber as long as the membrane is still depolarized from the preceding action potential. The reason for this is that shortly after the action potential is
11、 initiated, the sodium channels (or calcium channels, or both) become inactivated, and no amount of excitatory signal applied to these channels at this point will open the inactivation gates.,Channels Inactivated,Potassium and cardiac electrophysiology 钾与心肌电生理,钠钾泵的活动，是形成和维持细胞内外电位差及钠钾浓度梯度的主要因素 静息膜电位主
12、要是钾的平衡电位 (神经)细胞膜对钾的通透性是钠的100倍,Inside,一组离子通道,Relation of action potential and myocardial contraction 动作电位与心肌收缩的时相关系,Relation of action potential and electrocardiogram 动作电位与心电图的关系与区别,动作电位为单个心肌细胞的除极与复极电流，其基础为细胞膜离子通道电流 体表心电图为所有心肌除极与复极的综合向量,Sympathetic and parasympathetic controls of the heart electricit
13、y 交感神经与副交感神经对心电活动的调节,Adrenergic stimulation increases the heart rate by increasing ICa,L and If activity. Cholinergic stimulation decreases the heart rate by decreasing ICa,L and If activity.,交感与副交感神经系统 对心血管的支配,Normal electrocardiogram and cardiac Arrhythmias 正常心电图与心律失常,心律失常的常见原因有心肌缺血、低钾、交感兴奋、甲亢、病毒性
14、心肌炎等,房性早搏,心律失常的形成机制 Mechanisms of arrhythmias- Disturbances in impulse formation (冲动形成异常),Changes in automaticity of pacemaker cells自律性变化: increased depolarization because of enhanced -receptor activity during mental stress, fever, exercise, etc, leading to sinus tachycardia.窦性心动过速 常见于交感兴奋如心理应激、发热、运
15、动及甲亢等 窦性心动过速(120bpm),Sinus tachycardia (110bpm),Mechanisms of arrhythmias- Disturbances in impulse formation (冲动形成异常),Formation of abnormal pacemaker异位起搏: increased automaticity in non-pacemaker cells such as atrial and ventricular muscle, surpassing sinoatrial node and becoming pacemakers cells atr
16、ial or ventricular premature beats. 房性或室性早搏等 房性早搏(QRS正常，之前有P波) 室性早搏(QRS宽大畸形)与连发室早,正常传导,Mechanisms of arrhythmias- Abnormal conductance and reentry(异常传导与折返),Every cardiac cell is able to transmit impulses of excitation in every direction. 心肌具有向不同方向传导的特点 Normally, the action potential impulse will spread through the heart quickly enough that each cell will respond only once.,单向阻滞与折返,Mechanisms of arrhythmias- Abnormal conductance and r
