REVIEW J Neurocrit Care 2018;11(1):7-12 eissn 2508-1349 신경계중환자실에서흔한부정맥 김성환가톨릭대학교의과대학서울성모병원순환기내과 Management of Common Arrhythmia in the Neurological Intensive Care Unit Sung-Hwan Kim, MD Division of Cardiology, Department of Internal Medicine, Seoul St. Mary s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea Cardiac arrhythmias are a common problem in the neurological intensive care unit and represent a major cause of ischemic stroke. Significant arrhythmias are most likely to occur in elderly patients. In this review, we focus on three arrhythmias: premature beats, atrial fibrillation, and QT prolongation. The goal of this review is to provide a current concept of diagnosis and acute management of arrhythmias in the neurological intensive care unit. J Neurocrit Care 2018;11(1):7-12 Key words: Atrial premature complexes; Ventricular premature complexes; Atrial fibrillation Received May 8, 2018 Revised May 18, 2018 Accepted May 27, 2018 Corresponding Author: Sung-Hwan Kim, MD Division of Cardiology, Department of Internal Medicine, College of Medicine, Seoul St. Mary s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Korea Tel: +82-2-2258-6074 Fax: +82-2-591-1506 E-mail: sunghwan@catholic.ac.kr Copyright 2018 The Korean Neurocritical Care Society 서론 부정맥 (arrhythmia) 은심실의박동수와부정맥발생위치에따라서분류할수있다 (Fig. 1). 이중신경계중환자에게가장흔하게관찰될수있는것은조기심방수축 (premature atrial contraction, PAC) 과조기심실수축 (premature ventricular contraction, PVC) 이다. 조기수축은중환자뿐아니라, 정상일반인에게서도가장흔하게관찰되는부정맥인데, 1 증상을일으킬수있지만, 환자의경과를바꿀만큼위중한경우는없고일시적인경우가많다. 심방세동은고령, 중환자일수록발생률이높아질뿐아니라, 허혈성뇌졸중의중요한원인이된다. 2 QT 연장 (prolongation) 의원인은선천성과후천성으로나 눌수있는데, 후천성 QT 연장의가장흔한원인은약제와저칼륨혈증이며, 이는중환자실에서자주관찰되는것이다. 본고에서는위에서언급한조기수축, 심방세동, QT 연장에대해서살펴보고자한다. 본론 1. 심전도소견어떠한부정맥이든, 가장중요한것은심전도를통한정확한진단이다. 대부분의신경계중환자들은심전도모니터링을하고있게되며 ( 대부분 lead II), 이것만가지고도위의세가 cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. www.e-jnc.org 7
지부정맥뿐아니라다른대부분의부정맥진단이가능하다. 이후심전도소견은모두 lead II를기준으로설명하기로한다. 정상동리듬 (normal sinus rhythm) 일경우, 정상의 P wave 축을보이며, lead II에서는양성 (positive) 이다 (Fig. 2A). 양성의 P wave가일정한간격과적절한속도 (50-90회/ 분 ) 로관찰된다. 양성의 P wave를보이나간격이다소불규칙하면동성부정맥 (sinus arrhythmia) 이라고하며, 호흡에의한변화일가능성이가장높고, 임상적문제는전혀없다. 양성의 P wave가일정한간격으로나오지만, 느린경우는동성서맥 (sinus bradycardia), 빠른경우는동성빈맥 (sinus tachycardia) 이다. P wave 다음에일정한간격으로 QRS wave가나오는것으로보아, 방실전도 (atrioventricular conduction) 도적절한것을알수있다. Figure 1. Classification of arrhythmias. Arrhythmias can first be classified by ventricular rate. PAC, premature atrial contraction; AF, atrial fibrillation; AT, atrial tachycardia; AFL, atrial flutter; PSVT, paroxysmal supraventricular tachycardia; PVC, premature ventricular contraction; VT, ventricular tachycardia; VF, ventricular fibrillation; VFL, ventricular flutter. A A B B C D Figure 2. Electrocardiographic findings of premature beats and atrial fibrillation. (A) Red arrow indicates positive P wave in lead II, which is compatible with normal sinus rhythm. (B) Blue arrow indicates normal T wave, but the T wave, which the red arrow indicates, looks different, which means an ectopic P wave is superimposed on the T wave, i.e., premature atrial contraction. (C) Red arrow indicates a QRS wave with different morphology, which occurs in unexpected premature timing. Large R wave in lead II suggests that the ventricular outflow tract is the origin of premature ventricular contractions. (D) No discrete P wave and irregularly irregular QRS wave, which indicate atrial fibrillation. Figure 3. QT interval and its correction as heart rate (HR). (A) Usually, normal QT Intervals are less than half the RR Interval for heart rates below 100 bpm. (B) Electrocardiography machine provides QT interval and corrected QT interval (QTc). The measurement of QT interval by the machine is usually incorrect, but RR interval and 1/ RR are precise. Therefore, QT interval should be measured manually and 1/ RR could be found by simple calculation. 8
Sung-Hwan Kim Arrhythmia in Neuro-ICU 정상의 P wave 모양이아니면서예상되는시점보다먼저발생하는것이조기심방수축 (PAC) 이며 (Fig. 2B), 정상의 QRS wave 모양이아니면서예상되는시점보다먼저발생한것이조기심실수축 (PVC) 이다 (Fig. 2C). 뚜렷한모양의 P wave가관찰되지않고, QRS 간격이어떠한패턴도없이불규칙할때 (irregularly irregular), 심방세동이다 (Fig. 2D). QRS의시작부터 T wave의끝까지를측정한것이 QT 간격이며, 심전도기기에서기록된 QT 간격은정확하지않기때문에반드시직접측정해봐야한다 (Fig. 3A). 맥박수빨라지면 QT 간격이짧아지는것이생리적이며, 맥박수에따라정상 QT 간격의기준또한달라져야한다. 가장간략한방법은 QT 간격이 RR 간격의절반이내에드는지확인하는것이다 (Fig. 3A). 정량적으로평가하는방법은 QT 간격을심전도에서측정하고, 이에 1/ RR을곱하는것이다. 이계산은다소복잡하므로, 보통심전도에서기록되는그환자의 1/ RR을참고할수있다 (Fig. 3B). 2. 조기수축 1) 조기심방수축 (PAC) Premature atrial beat (PAB), atrial premature beat (APB), atrial premature contraction (APC), supraventricular ectopy는모두같은것을뜻하는용어이다. 빈도의차이가있을뿐거의모든일반인에게서나타나며, 고령, 심혈관질환이있을수록빈도는올라간다. 1 빈번하게관찰되는조기심방수축은심방세동및허혈성뇌졸중의예측인자이지만, 3 조기심방수축을치료하였을때심방세동및허혈성뇌졸중이감소한다는증거는없다. 그리고조기심방수축이워낙흔하며, 이를줄이기위한항부정맥제의부작용이무시못할정도임을감안하면앞으로도조기심방수축의치료가필요할것이라는연구결과가나오기는쉽지않을것으로생각된다. 조기심방수축이연달아나오는형태인심방빈맥 (atrial tachycardia) 이나인체삽입기기에서만관찰되는심방세동 (subclinical atrial fibrillation) 또한, 허혈성뇌졸중의예측인자일뿐치료가필요하다는증거는아직없는상태이다. 조기심방수축은견딜수없는증상을유발할때치료가필요할수있는데, 이런경우에도항부정맥제는가능한적은용량으로짧은기간동안유지해야한다. 베타차단제가우선적으로선택될수있으며, 이에효과가없을경우 propafenone, flecainide, amiodarone 등을사용할수도있으나, 부작용등고려할사항이많아서부정맥전문의에게의뢰하는것이안전하다. 2) 조기심실수축 (PVC) 아주흔하며, 실제치료가필요한경우가적다는점에서조기심실수축과조기심방수축은비슷하다. 다른점은위험도평가이다. 조기심방수축은발생하는위치, 원인보다발생빈도가중요하지만, 조기심실수축은발생위치, 원인이발생빈도보다도훨씬중요하다. 심실근육이정상인경우에발생하는특발성 (idiopathic) 조기심실수축은위험한것이아니며, 심지어조기심실수축이연달아나와서심실성빈맥이된다고하더라도대부분양호한경과를보이며, 증상이없고빈도가잦지않으면치료를하지않는경우도많다. 4 하지만비정상적인심실근육에의하여유발되는조기심실수축은장기적인예후의위험인자이며, 5 특히연달아나와서심실성빈맥이되는경우돌연심장사의원인이될수있어적극적인관찰과치료가필요할수있다. 6 따라서, 조기심실수축이발견되었을경우가장중요한것은원인질환의유무이다. 조기심실수축은너무도흔하게관찰되기때문에모든경우에, 심장초음파를시행해볼수는없다. 평소호흡곤란, 흉통, 실신등심장질환을의심할만한증상이있었는지를먼저확인해야한다. 그리고심전도소견이특발성조기심실수축을감별해내는데도움이되는데, 대부분의특발성조기심실수축은심실유출로 (ventricular outflow tract) 에서발생하여, II, III, avf에서크게양성인 QRS wave를보인다 (Fig. 4). 또한심실유출로에서발생하는조기심실수축의대부분은우심실유출로이며 V1에서음성의 QRS를보인다. 7 따라서, 평소에심장질환을의심할만한증상이없었고, 조기심실수축의모양이심실유출로를시사한다면, 특발성조기심실수축이라고판단할수있다. 특발성심실조기수축에서치료가필요한경우는견딜수없는증상을유발하거나지나치게자주발생하는경우이다. 지나치 Figure 4. Electrocardiographic findings of premature ventricular contractions from right ventricular outflow tract. In leads II and III, avf, a large R wave was shown (red arrow). In the V1, the QRS morphology of a premature ventricular contraction is mainly negative (red arrow). 9
게자주, 지속적으로발생하면심실기능을약화시킬수있다 (premature ventricular contractions induced cardiomyopathy). 지나치게자주 의기준은명확하지는않지만, 홀터검사에서반복적으로 15% 이상발견되는경우를말한다. 8 특발성조기심실수축, 특발성심실성빈맥의치료방법은조기심방수축과같이베타차단제등항부정맥제를사용해볼수있고, 9 특발성심실성빈맥의일종인섬유속심실성빈맥의경우 verapamil이선택이다. 10,11 약제에반응이좋지않은경우전극도자절제술도고려해볼수있다. 8 원인이되는심장질환이확인된조기심실수축혹은심실성빈맥은돌연심장사의위험이있고, 치료방침결정이어렵기때문에부정맥전문의에게의뢰하는것이바람직하다. 3. 심방세동 (atrial fibrillation) 1) 역학심방세동은전세계적으로 20세이상의성인대략 3% 의유병률을보이며, 고령일수록유병률은급격히늘어난다. 12 우리나라에서심방세동역학에관한자료는많지않은데, 건강보험공단자료에의하면, 30대남자의경우연간천명당 0.82 ( 남 ), 0.55( 여 ) 이나, 80대의경우 13.09( 남 ), 11.54( 여 ) 로급격히늘어난다. 13 심방세동, 특히초기심방세동의대부분은발작성이다. 발작성심방세동의경우, 증상이있을때심전도를기록하지못하면진단이되지않는다. 심방세동으로진단된환자의단지 1/8만이단순한정기심전도로확인된다. 14 따라서정기심전도로조사된, 위에언급된유병률은상당히저평가된것이확실하다. 실제 20년후에는지금보다심방세동환자가 2배증가할것이라는역학연구결과가있다. 15 중환자실환자의경우, 심방세동유병률은보다증가하고다양하여 5-46% 까지보고된다. 16,17 신경계중환자실의경우도마찬가지일것으로생각되며, 18,19 특히허혈성뇌졸중으로입원한환자의 20% 에서이미심방세동을가지고있다고보고된다. 20 2) 치료방침의결정심방세동의치료방침결정은크게두가지이다. 1 항응고요법, 2 리듬조절혹은맥박수조절 이다. 최근에는이에더하여, 좌심방이폐색술이새로운치료법으로추가되었으나, 중환자실상황에서는일반적으로고려되지않으므로본고에서는생략하겠다. 심방세동은여러불편한증상을일으킬수있지만, 임상적으로가장문제가되는것은색전, 뇌졸중발생가능성이다. 21 가장고위험군은승모판협착과비대심근병증이며, 와파린을이용한항응고요법이반드시필요하다 (American College of Cardiology/American Heart Association, European Society of Cardiolgy guideline, class I). 2,22 그외의환자에서 ( 소위 비판막성심방세동 ) 색전, 뇌졸중위험도는 CHA 2 DS 2 -VASc 점수로평가한다 (Table 1). 23 CHA 2 DS 2 -VASc 2점이상인경우항응고요법의적응증이된다. 최근직접작용항응고제 (direct oral anticoagulant 혹 non-vitamin K antagonist oral anticoagulant) 가많이쓰이고있는데, 이에관해서는생략하겠다. CHA 2 DS 2 - VASc 점수가 0점이면항응고요법의대상이되지않으며, 아스피린은심방세동환자의항응고요법으로추천되지않는다. 2,22,24 중환자실에서새롭게관찰되는심방세동역시허혈성뇌졸중의위험이있다. 25 발생 48시간이넘으면, 항응고요법이필요하지않은지고민해야한다. 중환자들의경우, 혈소판감소, 프로트롬빈시간연장등으로출혈경향이있는경우가많으며, 다른질환이병합된경우가많아서결정이어렵다. 심방세동환자에서, 맥박수조절과리듬조절중어떠한것이더좋은가 에대한논란의본격적인시작은 2002년 AFFIRM 연구이다. 26 비정상적인심방세동리듬을정상리듬으로바꾸려는노력이좋은결과를보일것으로예상하였지만, 결과는맥박수조절과리듬조절시도군에서뇌졸중발생률에차이가없었으며, 27 통계적으로유의하지않지만리듬조절시도군에서사망률이증가하는경향을보였다. 예상을벗어난이러한결과는여러가지로해석될수있지만, 가장큰이유는 리듬조절시도군 에서실제로정상리듬으로회복되고유지된환자가그리많지않다는점에있다. 부작용이많은 항부정맥제 를투여한 리듬조절시도군 에서, 사망률이개선되려면, 심방세동이정상리듬으로많이유지되어야하는데그 Table 1. CHA 2 DS 2 -VASc score Variable Point Congestive heart failure 1 Hypertension 1 Age 75 years 2 Diabetes mellitus 1 Stroke/TIA/thromboembolism 2 Vascular disease (prior MI, PAD, or aortic plaque) 1 Age 65-75 years 1 Sex category (=female) 1 TIA, transient ischemic attack; MI, myocardial infarction; PAD, peripheral arterial disease. 10
Sung-Hwan Kim Arrhythmia in Neuro-ICU 렇지못하였던것이다. 실제, AFFIRM 연구에서 정상리듬유지군 과 심방세동군 으로나눠서분석해보면 (on treatment analysis), 정상리듬유지군 에서뇌졸중이감소하는결과를보였다. 28 이와같은결과를놓고판단하였을때, 임상에서 리듬조절 을시도해야하는환자는, 실제로정상리듬으로잘유지가될 환자들이다. 아직병적인심방근육의변형이진행되지않은초기의환자들로발작성심방세동이대표적인경우이다. 29 지속성심방세동이라도 1년이넘지않았거나, 좌심방의크기가작은환자들도고려대상이된다. 중환자들을대상으로하였을경우, 정상동율동으로의회복가능성은전신상태가좋지않을수록낮아진다. 특히, 패혈증, 수술직후등교감신경이항진된상태에서는심장율동전환 (cardioversion) 이나 amiodarone 투여에도정상동리듬으로회복될가능성이적기때문에무리한시도는하지않는것이좋다. 심방세동발생 48시간이지나면심방의기절심근상태 (mechanical stunning) 발생가능성이높아지기때문에동율동전환이후오히려심방내혈전형성의가능성이높아진다. 따라서, 충분한항응고요법없이동율동전환을시도하는것은방법에관계없이색전증의위험이있다. 4. QT 연장 (QT prolongation) QT 연장의원인은선천성과후천성으로나눈다. 신경계중환자실에서문제가되는것은후천성인경우이다. 후천성 QT 연장의가장흔한원인은약제와저칼륨혈증이다. 안정제를포함한정신질환관련약제가잘알려져있지만, 거의대부분의약제가 QT 연장의원인이될수있다. 30 저칼륨혈증또한중요한 QT 연장의원인이다. 그다지심하지않은저칼륨혈증에도 QT 연장이뚜렷하게나타날수있으며, 중환자들에게흔하므로반드시유념해야한다. QT 연장의최종결과는다형성심실성빈맥 (torsades de pointes) 으로환자를사망에이르게할수있다. 가장중요한점은주치의가관심을가지고 QT 연장여부를관찰하면서예방하는것이다. 일단 QT 연장이확인된이후에는유발약제, 저칼륨혈증여부를확인하고교정한다. Torsades de pointes는초기에는비교적짧고스스로없어지기때문에 (self-limited), 심전도모니터링을잘관찰하지않으면발견하기어렵다. Torsades de pointes 가확인되면, 원인교정과함께마그네슘을혈중농도에상관없이정주한다 (4-6 g). 다형성심실성빈맥이관찰된다고하여 amiodarone을주입하면 QT 연장이더심해져서위험해진다. Isoproterenol이나임시박동조율기로맥박수를늘려주는것도도움이된다. 결론 신경계중환자들의특징 ( 여러질환이병합, 고령, 뇌졸중등 ) 은부정맥환자의위험인자와상당히겹친다. 뿐만아니라, 신경계중환자들의상당수인허혈성뇌졸중의가장중요한원인질환이심방세동이기때문에진단과치료원칙에대해서알아둘필요가있다. 또한, QT 연장은간과되기쉽지만위중한결과를초래할수있고예방이가능하기때문에치료과정에서반드시유념해두고있어야한다. REFERENCES 1. Conen D, Adam M, Roche F, Barthelemy JC, Felber Dietrich D, Imboden M, et al. Premature atrial contractions in the general population: frequency and risk factors. Circulation 2012;126:2302-8. 2. Kirchhof P, Benussi S, Kotecha D, Ahlsson A, Atar D, Casadei B, et al. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Eur Heart J 2016;37:2893-962. 3. Weber-Krüger M, Gröschel K, Mende M, Seegers J, Lahno R, Haase B, et al. Excessive supraventricular ectopic activity is indicative of paroxysmal atrial fibrillation in patients with cerebral ischemia. PLoS One 2013;8:e67602. 4. Prystowsky EN, Padanilam BJ, Joshi S, Fogel RI. Ventricular arrhythmias in the absence of structural heart disease. J Am Coll Cardiol 2012;59:1733-44. 5. Maggioni AP, Zuanetti G, Franzosi MG, Rovelli F, Santoro E, Staszewsky L, et al. Prevalence and prognostic significance of ventricular arrhythmias after acute myocardial infarction in the fibrinolytic era. GISSI-2 results. Circulation 1993;87:312-22. 6. Moss AJ, Hall WJ, Cannom DS, Daubert JP, Higgins SL, Klein H, et al. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. Multicenter Automatic Defibrillator Implantation Trial Investigators. N Engl J Med 1996;335:1933-40. 7. Badhwar N, Scheinman MM. Idiopathic ventricular tachycardia: diagnosis and management. Curr Probl Cardiol 2007;32:7-43. 8. Ling Z, Liu Z, Su L, Zipunnikov V, Wu J, Du H, et al. Radiofrequency ablation versus antiarrhythmic medication for treatment of ventricular premature beats from the right 11
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