电解质与心律失常疗

1、电解质紊乱与心律失常处理电解质紊乱与心律失常处理北京医院北京医院杨杰孚杨杰孚心肌动作电位的产生过程心肌动作电位的产生过程电解质对心电及心律的影响电解质对心电及心律的影响n主要影响心肌动作电位n对心肌应激性及传导性也有影响n严重电解质紊乱n激动起源异常n传导异常n心脏停搏n室颤电解质紊乱对心肌动作电位的影响电解质紊乱对心肌动作电位的影响项目项目 高钾高钾 低钾低钾 低钠低钠 高钙高钙 低钙低钙静息电位静息电位+-动作电位时程动作电位时程-+-+动作电位幅度动作电位幅度- 或或+-传导速度传导速度-不应期不应期 -+-+阈电位阈电位应激性应激性+-+高钾血症高钾血症（5.5mmol/l）心电图表现

2、心电图表现1.t波高尖波高尖2.qrs波振幅降低、时间变宽、波振幅降低、时间变宽、s波加深波加深3.st段下移段下移4.p波减小，甚至消失波减小，甚至消失5.各种心律失常（缓慢型为主）各种心律失常（缓慢型为主）n窦缓、窦性静止；窦缓、窦性静止；n传导阻滞：房内、房室、室内传导阻滞：房内、房室、室内n交界区心动过速、交界区心动过速、 心室自主心律、心室自主心律、 室颤室颤 、心室停搏、心室停搏 高血钾的高血钾的ecg改变改变高钾的处理高钾的处理1.纠正原发病及诱发因素纠正原发病及诱发因素2.促进钾排泄促进钾排泄输液输液+利尿利尿3.促进钾转移促进钾转移葡萄糖葡萄糖+胰岛素胰岛素4.对抗严重心律失

3、常对抗严重心律失常钙剂钙剂5.透析透析低钾血症低钾血症-心电图表现心电图表现1.u波增高波增高2.t波振幅降低、平坦或倒置波振幅降低、平坦或倒置3.st段下移段下移4.各种心律失常：各种心律失常：以快速性心律失常为主以快速性心律失常为主n窦性心动过速窦性心动过速n早搏，尤其是室早早搏，尤其是室早n交界区心动过速、交界区心动过速、 室速、室速、 室颤室颤低血钾时心电图低血钾时心电图u波改变波改变n随着血钾降低，随着血钾降低，u波不断增大波不断增大 低钾血症低钾血症-治疗治疗n纠正病因及诱因纠正病因及诱因n摄入不足摄入不足n丢失过多丢失过多n分布异常分布异常n补钾补钾n静脉静脉n口服口服镁离子异常

4、镁离子异常-低镁血低镁血（0.75mmol/l)原因（大致同低血钾）原因（大致同低血钾）n摄入减少摄入减少n营养不良营养不良n消化系统疾病消化系统疾病n吸收不良吸收不良n排除增加排除增加n肾脏疾病肾脏疾病n排泄增加排泄增加n其它其它n利尿剂的使用等利尿剂的使用等镁离子异常镁离子异常-低镁血低镁血（0.75mmol/l)n直接效应直接效应n对窦房结有直接变速效应对窦房结有直接变速效应n降低细胞内钾降低细胞内钾n镁是激活镁是激活na+-k+-atp酶酶n缺镁缺镁该酶活性下降该酶活性下降细胞内缺钾细胞内缺钾n增加细胞内钙增加细胞内钙n镁为钙离子拮抗剂镁为钙离子拮抗剂镁离子异常镁离子异常-低镁血低镁血

5、（0.75mmol/l)n镁离子异常通常合并钾离子异常镁离子异常通常合并钾离子异常n低钾血症低钾血症低镁血症低镁血症镁离子异常镁离子异常-低镁血低镁血（3.0mmol/l)n原因：少见原因：少见n甲状旁腺机能亢进、骨髓瘤或骨转移瘤甲状旁腺机能亢进、骨髓瘤或骨转移瘤n心电图表现：心电图表现：nst段缩短或消失（段缩短或消失（r波后即出现突然上升的波后即出现突然上升的t波）波）nqt间期缩短间期缩短n严重时严重时npr延长延长n房室阻滞房室阻滞n早搏、心动过速等早搏、心动过速等 高钙血症高钙血症（3.0mmol/l)治疗：治疗：n重点是原发病重点是原发病n骨髓瘤、甲旁亢等骨髓瘤、甲旁亢等n常合并低

6、血钾常合并低血钾低钙血症低钙血症（1.75mmol/l)n原因原因n慢性肾脏疾病：肾衰、肾小管酸中毒等慢性肾脏疾病：肾衰、肾小管酸中毒等n甲状旁腺机能降低甲状旁腺机能降低n心电图异常及机制：心电图异常及机制：n主要影响动作电位主要影响动作电位2相：延长相：延长2相复极时间相复极时间n心电图表现心电图表现nst段平直延长段平直延长nqt延长：由延长：由st段延长所致（段延长所致（t波不宽）波不宽）血钙异常的血钙异常的ecg改变改变低钙血症低钙血症（1.75mmol/l)n治疗：原发病治疗：原发病n慢性肾脏疾病：肾衰、肾小管酸中毒等慢性肾脏疾病：肾衰、肾小管酸中毒等n甲状旁腺机能降低甲状旁腺机能降

7、低n补钙补钙当使用洋地黄类药物时不宜同时用钙盐当使用洋地黄类药物时不宜同时用钙盐电解质对心电及心律的影响电解质对心电及心律的影响临床特点（1）n多数非单一电解质紊乱n如低钾常伴随低镁n常伴有酸碱失衡n高钾酸中毒n低钾碱中毒n掺杂因素多n本身疾病n肝肾功能n药物电解质对心电及心律的影响电解质对心电及心律的影响临床特点（2）n以钾离子对心肌细胞影响最明显n其次n钙离子n镁离子n钠离子电解质紊乱所致心律失常电解质紊乱所致心律失常心电图案例分析心电图案例分析case 1:which electrolyte problem is this tracing suggestive of?hyperkalem

8、ianhyperkalemiandiscussionnas the tracing shows, this patient has a regular rhythm at a rate of 101/min. the qrss are very wide; wider than those seen with ordinary bundle branch block. t-waves are tall in v1-3. these findings are all characteristic of hyperkalemia. the serum potassium level was 7.2

9、 meq/l. the rhythm may be sinus with the p-waves hidden in the st segment or sino-ventricular rhythm if p-waves are truly not present. atrial muscle is more sensitive to hyperkalemia than the specialized conduction system is. at certain levels of hyperkalemia, the atrial muscle becomes inexcitable (

10、paralyzed) while the special internodal conduction system is still excitable. then, the sinus impulses will conduct to the ventricles through the conduction system without the atria being depolarized thus referred to as sino-ventricular rhythm.尿毒症高钾尿毒症高钾-窦室传导窦室传导窦室传导窦室传导ecg表现：表现：1.p波消失波消失 2.qrs宽大畸形宽

11、大畸形 3.t波高尖对称波高尖对称 4.ecg表现为表现为qrs-t序列序列case 2:anteroseptal infarct or pseudoinfarction pattern from hyperkalemia?nwhich of the following conditions is responsible for the st elevation in leads v1-2? choose from the list below.na) acute anteroseptal infarctb) pseudoinfarction pattern from hyperkalemia

12、pseudoinfarction pattern from hyperkalemianpseudoinfarction pattern from hyperkalemia is correct.sinus tachycardia at a rate of 130 beats per minute is present. the st segment is elevated in v1 and v2, raising the possibility of acute anteroseptal myocardial infarction. however, the t wave is very t

13、all, narrow, pointed, and tented; and the qrs is wide, measuring 140 msec.nthese findings are characteristic of hyperkalemia. it is well known that hyperkalemia can cause st-segment elevation (pseudoinfarction pattern or dialyzable current of injury).nthis tracing is from a patient with a serum pota

14、ssium level of 7.5 meq/l during diabetic ketoacidosis, who also is in renal failure and taking an angiotensin-converting enzyme inhibitorcase 4hypocalcemia and hyperkalemianhypocalcemia and hyperkalemia is correct.ndiscussionnthe qt interval is long. when the long qt interval is due to a long st seg

15、ment with a delayed onset of the t wave, it is specific for hypocalcemia. besides, the t waves are tall, narrow, and pointed and are highly suggestive of hyperkalemia. this combination of electrolyte problems is common in patients with chronic renal failure, which this patient has. the serum potassi

16、um level was 8.2 meq/l and calcium 5.4 mg/dl at the time.case 51.病史患者病史患者 女女 26岁岁n全身紧缩感全身紧缩感12年，间断抽搐发作年，间断抽搐发作n以以“癫痫癫痫”收住神经科多次收住神经科多次2.查体：神经肌肉应激性查体：神经肌肉应激性 紧张、恐惧、反射亢进紧张、恐惧、反射亢进“面神经征面神经征+“束臂试验束臂试验+”3.ecg：qt明显延长明显延长怀疑长怀疑长qt综合征收住心内科综合征收住心内科qt/qtc:528/561化验检查化验检查n生化：生化：nuric:109umol/l nck:1056u/l nld：56

17、4u/l nhbdh：299u/l nca:1.09mmol/l nip:2.27mmol/l n余无异常余无异常 nck-mb tnt正常正常n血清血清mg:0.7mmol/l化验检查化验检查n血清血清pth3ng/mln24小时尿小时尿nca 1.708mmol (2.5-7.5)n尿尿ip23.884mmol (16-42)诊断：甲状旁腺功能减低诊断：甲状旁腺功能减低确诊标准：确诊标准：n临床表现临床表现n神经肌肉应激性增高神经肌肉应激性增高“面神经征面神经征+，“束臂试验束臂试验+”necgnqt延长（由延长（由st段平直延长所致）段平直延长所致）n化验化验n血钙降低血钙降低n血磷升高血磷升高治疗治疗n补充钙剂补充钙剂n一周后临床症状明显改善一周后临床症状明显改善n二周后临床症状基本消失二周后临床症状基本消失n典型的体征消失典型的体征消失n心电图恢复慢心电图恢复慢此病例经验及教训此病例经验及教训n误诊误治误诊误治12年年n误诊为癫痫误