Considerations about the polemic J point location

Transcription

1 Considerations about the polemic J point location

2 V) The J-point of the electrocardiogram Approximate point of convergence between the end of QRS complex and the onset of ST segment. It is considered the point at which the QRS complex finishes and the ST segment begins.. The J-point is an essential landmark for measuring QRS duration and ST segment elevation and/or depression. J-point represents approximate the end of depolarization and the beginning of repolarization as determined by the surface ECG. There is an overlap of 10 milliseconds. (1) The J point is used to measure the degree of ST elevation or depression present. It is very important in ACS- ST segment elevation myocardial infarction (STEMI). The TP segment of precedent beat and the PRs or PQs segment (PRs), are used as reference as the isoelectric line. The J-point TPs PRs ST 1. Mirvis DM. Evaluation of normal variations in S-T segment pattern by body surface mapping: S-T segment elevation in absence of heart disease. Am J Cardiol 1982;50:122

3 TP-s PRs Answer: using the PRs and TPs of precedent beat as isoelectric line. ST elevation must be measured at the beginning on J-point.

4 The "tangent" This complex is commonly called a "fireman's cap" because it resembles the profile of a firefighter's helmet. Seasoned medics will recognize this as trouble because of the elevated S-T segment. STsegment elevation = 4mm. Look at the tracing. Remember the J point is where the S wave makes a right turn toward the T wave.

5 The J-point is easy to identify when the ST segment is horizontal and forms a sharp angle with the last part of the QRS complex. However, when the ST segment is sloped or the QRS complex is wide, the two features do not form a sharp angle and the location of the J-point is less clear. There is no consensus on the precise location of the J-point in these circumstances. Two possible definitions are: I) The point at which the ECG trace becomes more horizontal than vertical. In these cases The tangent line method is appropiate The tangent line

6 IV) When the upstroke of the S wave has not a clear J-point of inflection, the tangent line method is ideal 70% >29% <1% A B C 70% >29% <1% A B C rs QS qrs rs QS qrs Tangent lines The three possible QRS patterns in V1-V2 in uncomplicated Complete LBBB: rs (70%), QS (>29%) and qrs (<1%).

7 PROPER MEASUREMENT OF QRS DURATION Real end of QRS False end of QRS Incorrect end of QRS Correct end of QRS The first change in the slope Is the end of QRS Outline that shows the proper measurement of QRS complex duration.

8 A J-point B V 2 ST elevation J-wave V 4 J-point D C New J-wave Terminal QRS slurring J-wave avf V 4 A and B classic definition of ERP always with ST segment elevation A) ERP with only ST segment elevation B) ERP with ST segment elevation and J-point at the end of J wave. C and D New concept of ERP without ST segment elevation C) J-point elevation and terminal QRS slurring without ST segment elevation. ) The first point of inflection of R wave descendent ramp is considered the real J-point. In these cases The tangent line method is ideal. D) J-wave without ST segment elevation 1. Pérez MV, Friday K, Froelicher V. Semantic confusion: the case of early repolarization and the J point. Am J Med Sep;125:

9 The figure shows in lead V4 the "upwardly concave" the classic "hooked J-point" in lead V4 typical of benign early repolarization pattern. ST-elevation looks like a "smiley face."

10

11

12 Brugada Type 1 ECG pattern High take-off of does not coincide with J-point. Absence of clear r wave At 40ms of high tale-off the decrease in amplitude of ST segment is 40mm or 0.4mV J-point Upwardly Convex ST-segment elevation upwardly convex The tangent line Typical electrocardiographic pattern, Brugada Type 1: ST segment elevation 2 mm, upwardly convex and followed by inverted symmetric T wave in the right precordial leads (V1, V2 or V3). The QRS duration is longer than RBBB and there is a mismatch between V1 and V6. 1. Nishizaki M, Sugui K, Izumida N et al. Classification and assessment of computerized diagnostic criteria for Brugada-type electrocardiograms. Heart Rhythm Nov;7:

13 Type 1: Brugada pattern High take-off Type 2: Saddle-back pattern 40 ms 80 ms β 80 ms Type 2: The r wave is rounded, wide and usually of relatively low voltage The angle between the upslope of the S-wave and the downs lope of the r'-wave. (β angle) > 58. Descending arm of r coincides with beginning of ST segment (J-point) Duration of the base of the triangle of r at 5mm from high take-off >3.5mm The QRS duration is longer in Brugada pattern type 2 than in other cases with r in V1 and there is a mismatch between V1 and V6. In Brugada pattern the QRS complex end is earlier in V6 than in V1-V2. 1. Bayés de Luna A, Brugada J, Baranchuk A, Borggrefe M, Breithardt G, Goldwasser D, Lambiase P, Pérez-Riera AR, Garcia Niebla J, Pastore CA, Oreto Guiuseppe, McKenna William. Zareba W, Brugada R, Brugada P. Current electrocardiographic criteria for diagnosis of Brugada pattern: a consensus report. Journal of Electrocardiol. 2012; 45: Chevallier S, Forclaz A, Tenkorang J, et al. New electrocardiographic criteria for discriminating between Brugada types 2 and 3 patterns and incomplete right bundle branch block. J Am Coll Cardiol.2011 Nov 22;58:

14 Type-1 ECG Brugada pattern: J point and ST segment elevation 2 mm, with upper convexity(1a) or descending oblique rectilinear(1b) and negative symmetrical T wave on right precordial leads (V1-V2 or V1-V3) and/or high right precordial leads V 1H, V 2H and V 3H. Sub- Types-1 ECG Brugada pattern Subtype 1A Subtype 1B J-point Upwardly convex ST segment ST-segment rectilinear oblique descendent with the tangent line method is not possible to know J-point localization

15 J-point J-point J-point The patient was a young symptomatic (repetitive syncope episodes) Thai man, with positive familial background of SCD in young first degree relatives. He died 24h after performing this ECG. The ECG shows persistent ST segment elevation in the inferior and low lateral precordial apical leads (V5-V6), associated with concomitant reciprocal or mirror image in the anteroseptal wall that was not modified with the use of sublingual nitrate in absence of hypothermia, electrolyte imbalance or ischemia.

16 Sub type IC was denominated LAMBDA wave by Ihor Gussak et al(1) The tangent line is very appropiate for this subtype J-point J-point J-point Sub-type IC: ST-segment elevation is triangular or coved to the top ( coved type ) 2mm (0.2mV), and followed by negative T wave located in inferior or inferoapical leads. 1. Gussak I, Bjerregaard P, Kostis J. Electrocardiographic "lambda" wave and primary idiopathic cardiac asystole: a new clinical syndrome?j Electrocardiol 2004;37:

17

18 A B C J point PR interval J point J point TP Segment A) A normal ECG complex shows TP segment and PR segment, which may be used as reference points to the isoelectric line. B) The ST-segment is measured the J point. This ST-segment shows ST-segment depression of almost 5 mm. C) ST-segment elevation of approximately 45 mm is depicted.

19 This 12-lead ECG shows acute anterior STEMI in the presence of right bundle branch block, but you really need a trained eye to see it. We talk a lot about the rule of appropriate T-wave discordance with bundle branch blocks. What makes this case difficult is the fact that the T-waves are appropriately discordant. However, the J-points are concordant in leads V1-V4!

20 In leads V1-V3 the T- waves are appropriately discordant. J point However, the J-points are inappropriately concordant. This is normal and suggestive of acute STEMI. If you look carefully you will see that the point at which the QRS complex turns into the ST-segment (the J- point or junction point) is elevated above the isoelectric line. That s abnormal for right bundle branch block. In fact, if the J-point isn t isoelectric in the right precordial leads it should be slightly depressed (in the same direction as the T-waves).

21 Lead V4 looks the most abnormal. J point The tangent line In lead V4, once again the trick is to accurately locate the J-point. Once that is accomplished it becomes obvious that ST-elevation is present. The T-waves are appropriately discordant. If you re still having doubts, consider that Q-waves are present in leads V1-V4. to consider the company that any ECG abnormality keeps. Finally, let s look at leads III and avf.

22 In the context of J-point elevation in the anterior leads, the ST-depression in leads III and avf must be presumed to be reciprocal changes. We are forced to assume that these are reciprocal changes. Once again, it s the sum of all these abnormalities that is significant. They are more than the sum of their parts. This patient was in fact diagnosed with an acute anteroseptal ST-elevation myocardial infarction.

23 Man who had coronary revascularization a time ago. Continuous Holter monitoring during an episode of angina and concomitant ST segment elevation and ischemic giant J-wave "lambda-like type associated with Premature Ventricular Contractions with Bigeminy sequence and very short coupling. The PVCs disappear immediately after cessation of vasospastic ischemia with administration of sublingual nitrate

24