規(guī)則心律變化背后的機制是什么 來自書心劍律 00:00 04:59
English audio presented by Dr.Ethan（杜先鋒）
素材來源：
JOSEPHSON AND WELLENS ECG LESSONS
Heart Rhythm 2019, 16 (3) :486-488
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病 例 簡 介 Brief introduction
患者女性，41歲，既往“突發(fā)心悸3年”，每次持續(xù)數(shù)分鐘后可自行停止，近兩月來發(fā)作較前頻繁，心電圖如圖1所示。
The ECG shown in Figure 1 was recorded in a 41-yearwoman with a 3-year history of palpitations of sudden onset, which lasted a few minutes and terminated spontaneously. The frequency of those episodes had increased during the past 2 months.
圖1. 12導聯(lián)心電圖顯示：節(jié)律規(guī)則的窄QRS波變?yōu)閷挻驫RS波合并LBBB，同時心率加快，在2個窄QRS波之間可見低平的P波。
Figure 1: 12lead electrocardiogram showing a change from a regular rhythm with a narrow QRS to a much faster regular rhythm with left bundle branch block. Lowvoltage P waves seem to be located between 2 narrow QRS complexes.
1、圖1左側記錄的窄QRS波為何種心律？
1、What kind of narrow QRS rhythm is present on the left side of the recording?
2、圖1右側記錄的寬QRS波為何種節(jié)律？
2、What kind of wide QRS rhythm is present on the right?
3、窄QRS波和寬QRS波心律之間是否存在共同的心動過速機制？
3、Is there a common tachycardia mechanism between the narrow and the wide QRS rhythm?
討 論 Discussions
1. 房波在心率90次/分的窄QRS波心律時難以識別。P波在Ⅱ、Ⅲ 、aVF導聯(lián)中，呈負向、窄且低平；在V2-V6導聯(lián)中，P波似乎位于T波終末。圖中未見竇性心律。觀察窄QRS波顯示：在其末端存在負向房波與前面提及低平的房波極性一致，并精確地位于2個QRS波之間。如果判斷正確，房室呈2:1關系。
1. During the narrowQRSrhythm, which has a rate of 90/min, atrial activity is difficult to identify. P waves, which are narrow and low in voltage and negative in leads II, III, aVF, and V2–V6 seem to be present at the end of the T wave. No sinus rhythm is present. Examination of the narrow QRS complexes reveals a negative deflection at their end with the same polarity as the low-voltage atrial deflections described earlier, exactly between 2 QRS complexes. If correct, there are 2 atrial deflections with 1 QRS complex.
2. 在該心電圖的中間段，心律變?yōu)?80次/分的寬QRS波心動過速。其QRS波的寬度為130ms伴左束支傳導阻滯（LBBB）圖形。心動過速時P波無法識別，但根據(jù)QRS波的形態(tài)和寬度，提示室上速伴LBBB。
2. In the middle of the tracing, the rhythm changes into a wide QRS tachycardia with a rate of 180/min. The QRS is 130 ms wide and has a left bundle branch block (LBBB) configuration. No P waves can be identified during the tachycardia, but QRS configuration and width suggest a supraventricular tachycardia with LBBB.
3. 結合以上兩點的討論，發(fā)現(xiàn)寬QRS波心動過速的頻率恰好是窄QRS波的2倍。在窄QRS波心動過速中，房波與QRS波的間期固定。故P波和QRS波之間存在固定的2:1的關系?；赑波的形態(tài)，考慮有2種診斷可能：
3. Combining the findings described in 1 and 2, we note that the wide QRS tachycardia has exactly twice the rate of the episode with the narrow QRS. In view of the fixed distance between the atrial deflections and the QRS when the QRS is narrow, we conclude that, at that time, a fixed 2:1 relation between P waves and QRS was present. Two possible diagnoses should be considered in view of the Pwave configuration：
A. 低位房速，起源靠近房間隔，先以2:1房室傳導，后轉變?yōu)?:1房室傳導伴LBBB。
A. Low atrial tachycardia, with an origin close to the interatrial septum with 2:1 AV conduction to the ventricle changing to 1:1 AV conduction with LBBB.
B. 房室結折返性心動過速（AVNRT），先以1:1傳導至心房，并以2:1傳導至心室，后變?yōu)?:1傳導至心室伴LBBB。
B. Atrioventricular nodal reentrant tachycardia(AVNRT),initially with 1:1 conduction to the atrium and 2:1 conduction to the ventricle, changing to 1:1 conduction to the ventricle with LBBB.
B的可能性較大，因為在窄QRS波心動過速發(fā)作時，P波恰好精確位于2個QRS波之間，該診斷在電生理檢查中得到了證實（圖2）?？梢娗皞鱄is電圖與逆?zhèn)鞯姆坎ㄩg期為60ms，為典型慢-快AVNRT間期。1:1傳導至心室時出現(xiàn)LBBB，可能是因為第3相束支阻滯或是左束支被逆行侵入所致。該患者接受導管射頻消融行房室結慢徑改良。
Possibility B is favored because of the P location exactly between 2 QRS complexes during the episode with a narrow QRS. That diagnosis was confirmed during electrophysiologic study (Figure 2). Note that the distance between the anterograde Hisbundle electrogram and the retrograde atrial deflection measures 60 ms, a typical time interval in slow/fast AVNRT. The LBBB during 1:1 conduction to the ventricle can be the result of either phase 3 bundle branch block or retrograde invasion into the left bundle branch. Therapy consisted of radiofrequency catheter ablation of the slow AV nodal pathway.
圖2. 12導聯(lián)心電圖伴3個心內電圖，來源于冠狀靜脈竇近端及遠端和His束。從窄QRS波變?yōu)?倍心率的寬QRS波時，在2:1房室傳導中，His波位于房波之前，提示了房室結內形成沖動逆?zhèn)髦列姆?span>。
Figure 2. 12lead electrocardiogram with 3 intracardiac registrations, from proximal and distal coronary sinus and His bundle, during the change from a narrow QRS to a wide QRS with doubling in rate. Note that during the 2:1 AV relation, the Hisbundle electrogram is located before the atrial electrogram, indicating impulse formation in the AV node with retrograde conduction to the atrium.
審 校：杜先鋒
編 譯：傅國華
編 輯：方任遠
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