![]() Horizontal or downsloping ST depression ≥ 0.5 mm at the J-point in ≥ 2 contiguous leads indicates myocardial ischaemia.ST depression can be either upsloping, downsloping, or horizontal.Morphology of the Elevated ST segment Myocardial InfarctionĪcute STEMI may produce ST elevation with either concave, convex or obliquely straight morphology. The most important cause of ST segment abnormality (elevation or depression) is myocardial ischaemia or infarction.The ST Segment represents the interval between ventricular depolarization and repolarization.The ST segment is the flat, isoelectric section of the ECG between the end of the S wave (the J point) and the beginning of the T wave. ECG changes are an insensitive means of detecting LVH (patients with clinically significant left ventricular hypertrophy seen on echocardiography may still have a relatively normal ECG).Voltage criteria alone are not diagnostic of LVH.R wave in V5 or V6 plus S wave in V1 > 35 mm.ST segment depression and T wave inversion in the left-sided leads: AKA the left ventricular ‘strain’ pattern Increased R wave peak time > 50 ms in leads V5 or V6 Largest R wave plus largest S wave in precordial leads > 45 mm R wave in V5 or V6 plus S wave in V1 > 35 mm R wave in lead I + S wave in lead III > 25 mm Voltage criteria must be accompanied by non-voltage criteria to be considered diagnostic of LVH. ![]() ![]() QRS complexes < 100 ms wide (unless co-existent interventricular conduction delay present)Ī regular, narrow-complex heart rhythm at 60-100 bpm Normal P wave axis: P waves upright in leads I and II, inverted in aVR Regular rhythm at a rate of 60-100 bpm (or age-appropriate rate in children)Įach QRS complex is preceded by a normal P wave
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