indications and complications of permanent pacemakers




antiarrhythmics  抗不整脈薬;           

atrioventricular (AV) block  房室ブロック ... 房室から心室への電気インパルスの伝導障害;

calcium-channel blocker  カルシウムチャネル遮断薬 ... 高血圧治療薬;

complication  合併症;            

dizziness  めまい;    

electrocardiogram  心電図;  

electrolyte disturbance  電解質障害;             

erosion  びらん;        

exercise intolerance  運動不耐性 ... 運動不耐性とは患者が健常者とレベルや時間運動を行うことが出来ない状態、または運動後に重度の痛み、疲労、または他の好ましくない結果が現れる状態;

follow-up treatment  継続治療;         

heart failure  心不全;            

hypothyroidism  甲状腺機能低下症;

implantation procedure  埋め込み処置;        

indication  適応症;   

lightheadedness  めまい;     

palpitation  動悸;     

perforation  穿孔;     

permanent pacemaker  恒久型ペースメーカ;            

pneumothorax  気胸;            

retrograde depolarization  逆行性脱分極;    

subclavian vein  鎖骨下静脈;            

syncope  失神;           

thrombosis  血栓症; 

weakness  虚弱;       

β-adrenergic blocker  β-アドレナリン遮断薬 ... 心血管疾患治療薬


Indications for a Permanent Pacemaker



Permanent pacemakers are generally used to palliate symptoms of bradycardia or to prevent symptoms from worsening for patients with symptomatic bradycardia.



Symptoms of bradycardia include dizziness, syncope, exercise intolerance, and symptoms of heart failure.



Since these symptoms are nonspecific, diagnostic data that indicate association between symptoms and bradycardia are required before a permanent pacemaker is used. 



If a patient has persistent bradycardia because of a complete AV block, his or her electrocardiogram may indicate necessity of a permanent pacemaker.



For a patient with intermittent bradycardia, diagnostic tests that indicate necessity of a permanent pacemaker include 24-hour ambulatory monitoring test, continuous loop recorder test, implantable event monitoring test, and electrophysiology test. 



Before a permanent pacemaker is used for a patient, causes of the bradycardia should have been excluded and test result that the patient has taken should indicate necessity of the pacemaker.


Causes of symptomatic bradycardia include hypothyroidism, electrolyte disturbances, and several medications such as β-adrenergic blockers, calcium-channel blockers, and antiarrhythmics. 



Complications of Permanent Pacemakers



Complications occur in less than 2% of patients who have implantation procedure of permanent pacemakers.  The complications include pneumothorax, perforation of the atrium or ventricle, lead dislodgement, infection, and erosion of the pacemaker pocket.



10 to 20% of patients have thrombosis of subclavian vein.  This complication increases for those who have  permanent pacemakers using multiple leads and is often asymptomatic.



When pacemaker operates in DDD pacing mode, if the atrial lead senses retrograde depolarizations because of ventriculoatrial conduction, tachycardia may occur as a complication.  This tachycardia is referred to as pacemaker-mediated tachycardia.


As a result, the heatbeats of the patient become as rapid as the upper limit of the pacemaker.



Pacemaker-mediated tachycardia can be prevented by reprogramming the pacemaker, for example, enlarging postventriculoatrial refractory period.



If patients use dual-chamber pacemakers for treatment of sinus node disease, they are at risk of future atrial fibrillation.



If ventricular pacing of the dual-chamber pacemakers is minimized, the risk of atrial fibrillation is said to be reduced by 40%.



Symptoms caused by the absence of AV synchronism during ventricular pacing of pacemaker include weakness, lightheadedness, exercise intolerance, and palpitations.



These symptoms can be alleviated by settings of pacemakers.  AV synchronism can be restored in DDD pacing mode or if AV conduction remains intact, in AAI pacing mode.



Problems that are likely to occur during long-term follow-up treatment after pacemaker implantation include failure to pace, failure to sense, and changes in the pacing rate.


Causes of these problems include programming mistakes, lead breakage, insulation failure, generator malfunction, and dead battery.