图1:心电图
Q1.完全性右束支传导阻滞
Q2.不符合
Q3.提示心肌缺血
心电图解析
在图1中,我们预计ST-T改变与3个主要导联中QRS波终末部分相反(即V1为负值,I、V6 为直立)。然而,I和V1导联出现ST变平,V6导联出现T波倒置。V2至V6导联中对称性的T波倒置也不能仅仅用RBBB解释。
临床印象
该心电图考虑:窦性心动过缓,窦性心律失常,完全性RBBB,ST-T改变(原发性)。此外,多个导联存在Q波,其中aVL导联中的Q波明显比预期更深。除了RBBB之外,我们还要考虑心肌梗塞/缺血,这可能是最近发生的甚至是急性的。
What type of conduction defect is present?
Are ST-T waves doing what you'd expect given the presence of this conduction defect?
Clinically - What else may be going on?
INTERPRETATION: The rhythm is sinus. The rate is slow (~50-55/minute) - with slight irregularity making this sinus bradycardia and arrhythmia. The PR interval is normal. The QRS is obviously long. Recognition of QRS widening at this point is indication to STOP - and figure out WHY the QRS is wide before going on:
Assessment of QRS Widening: - The 3 KEY leads to assess in order to determine the reason for QRS widening are leads I, V1, and V6. Right-sided Lead V1 shows an rSR' complex (with a taller right rabbit ear). Left-sided Leads I and V6 both have a relatively wide terminal S wave (albeit the S in lead I is modest in size). QRS morphology is therefore consistent with complete RBBB = Right Bundle Branch Block (Figure 2)
Returning to Our Systematic Approach: The QT interval is less relevant in the setting of BBB (BBB by itself may prolong the QT). Regarding Axis - there is no hemiblock (Other than the presence or absence of associated left anterior or posterior hemiblock - the concept of axis means little in the setting of BBB). There is no chamber enlargement.
Q-R-S-T Changes - There are some relatively larger-than-expected Q waves in the lateral leads (I,V5,V6 - and especially aVL) - which could reflect infarction of uncertain age. The tall R wave in lead V1 is from RBBB. An important finding in Figure 1 is that ST-T waves are not as one would expect for simple BBB (Figure 3).
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KEY Rule - Normally when there is typical RBBB or LBBB - the ST segment and T wave should be oriented opposite to the last QRS deflection in the 3 KEY leads (arrows in Figure 3). Deviation from this pattern in any of the 3 KEY leads (I, V1 or V6) is abnormal - and indicates a primary ST-T wave change (suggesting ischemia or infarction may be occurring).
In Figure 1 - One would expect ST-T waves to be opposite to the last QRS deflection in the KEY leads (ie, negative in V1 - and upright in I,V6). Instead - there is ST flattening in leads I and V1, and a negative T wave in lead V6. Deep, symmetric T wave inversion in leads V2 thru V6 is also clearly more than what one should see with simple RBBB.
CLINICAL IMPRESSION: We interpret this ECG as showing sinus bradycardia and arrhythmia with complete RBBB and primary ST-T wave changes. In addition - there are Q waves in multiple leads with a clearly deeper-than-expected Q wave in lead aVL. We worry about infarction/ischemia in addition to RBBB, which could be recent or even acute. Clinical correlation is urged.
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