What is discordance in ECG?
ST-elevation is “excessively discordant” when the ST-elevation (measured at the J-point) is > 0.25 or 25% the depth of the S-wave. ST-depression is “excessively discordant” when the ST-depression (measured at the J-point) is > 0.3 or 30% the height of the R-wave.
What is the J point?
The J point is the the junction between the termination of the QRS complex and the beginning of the ST segment. The J (junction) point in the ECG is the point where the QRS complex joins the ST segment.
What is concordant ST elevation?
Concordant ST elevation ≥ 1 mm in ≥ 1 lead. Concordant ST depression ≥ 1 mm in ≥ 1 lead of V1-V3. Proportionally excessive discordant STE in ≥ 1 lead anywhere with ≥ 1 mm STE, as defined by ≥ 25% of the depth of the preceding S-wave.
What is a discordance?
Definition of discordance 1 : lack of agreement or harmony : the state or an instance of being discordant.
What is appropriate discordance?
The diagnosis of STEMI in LBBB is dependent on the “Rule of Appropriate Discordance,” which means that, in normal LBBB (without MI), the ST segment (and usually T-wave) are in the opposite direction (discordant to) the majority of the QRS.
Can Sgarbossa criteria be applied to a paced rhythm?
The Sgarbossa and Smith-modified Sgarbossa criteria have been documented to enhance the diagnosis of STEMI in the setting of LBBBs. However, there is a growing body of literature that suggests that these criteria can also be applied for the diagnosis of STEMI in patients with paced rhythms.
What is J wave on ECG?
The “J wave” (also referred to as “the Osborn wave,” “the J deflection,” or “the camel’s hump”) is a distinctive deflection occurring at the QRS-ST junction. In 1953, Dr. John Osborn described the “J wave” as an “injury current” resulting in ventricular fibrillation during experimental hypothermia.
What is meant by J point elevation?
The term J-point elevation represents a family of ECG findings. It has been described in several metabolic disorders most notably hypothermia (abnormally low body temperature). Subtle nuances in its pattern may point to other conditions, the most common of which is termed ‘early repolarization’.
What are concordant leads?
Precordial concordance, also known as QRS concordance is when all precordial leads on an electrocardiogram are either positive (positive concordance) or negative (negative concordance).
Appropriate discordance describes a pattern of repolarization abnormality (seen with left bundle branch block, paced rhythms, VT, PVCs, etc.) in which the ST segment and T wave are directed opposite to the main vector of the QRS complex: ST depression and T wave inversion in leads with a dominant R wave.
What does inappropriate concordance mean on an EKG?
Now, when the EKG shows inappropriate concordance (J-point and ST-segment elevation in positive leads, and J-point and ST-segment depression in negative leads), there is a 90% likelihood that the patient is having a STEMI.
What is excessive discordance in a STEMI?
Inappropriate concordance of ≥ 1 mm is highly predictive of STEMI. The middle beat illustrates Sgarbossa Criteria C, ≥ 5 mm excessive discordance. Criteria C is the weakest criteria of the three, and may indicate a STEMI only 50% of the time.
Why are the top two ECG values false positives?
Thus, the top two ECGs with excessively discordant ST elevation are false positives. During both presentations, the patient was fluid overloaded, and had decompensated heart failure with a very low ejection fraction. It is likely that severe cardiomyopathy and loading conditions result in false positives.
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