J-point
| Condition | EKG Changes |
|---|---|
| Normal | The point where QRS complex joins the ST segment. Often slightly above the baseline. |
| Early Repolarization Pericarditis Myocardial ischemia/ Infarction | J-point elevation |
| Hypothermia | J-waves/ Osborne waves: long slow positive deflection just before the J-point. |
ST-segment
| Condition | EKG Changes |
|---|---|
| Normal | flat, isoelectric line between J-point and the start of T-wave |
| 1. Acute MI 2. Printzmetal’s angina 3. Takotsubo cardiomyopathy | ST- elevation: Classically, STEMI has been associated with a “convex upwards” morphology- but the morphology may be convex/ concave/ oblique! Reciprocal changes are typically seen with MI and Printzmetal’s angina but usually absent with Takotsubo. Changes in Printzmetal’s angina are usually transient. |
| Pericarditis | ST-elevation- usually concave upwards. Reciprocal ST depression and PR elevation in leads aVR and V1. |
| Early Repolarization | ST-elevation- J-point notching is sometimes seen with early repolarization |
| LBBB/ Paced rhythm/ LVH | ST- elevation/ depression: main vector of QRS and ST-T segments are usually discordant. |
| Ventricular aneurysm | Persistent ST segment elevation after an MI, along with Q-waves. |
| Raised Intracranial Pressure (Intracranial bleed) | ST-elevation/ depression with deep inverted T-wave inversions |
| Brugada syndrome | Brugada Sign: ST elevation with a coved morphology and a partial RBBB pattern in V1-V2. |
| J-point elevation | can simulate ST elevation |
| Sodium Channel Blocking Drugs | QRS prolongation, tall R wave in aVR, QTc prolongation. can also cause ST elevation |
| LAD lesion | De Winter pattern: Upsloping ST-depression at J point in precordial leads that is >1mm + reciprocal ST elevation in aVR + tall and symmetrical T waves in precordial leads (De Winter T-waves) |
| Myocardial Ischemia | Horizontal/ downsloping ST depression ≥ 0.5 mm at the J-point in ≥ 2 contiguous leads indicates myocardial ischaemia Diffuse ST depression with ST elevation in aVR is seen with LAD lesions as well as 3 vessel disease. |
| Tachycardia (sinus/ supraventricular) | widespread ST depression |
| Digoxin effect | Downsloping ST depression creating a “reverse check mark” appearance. |
| Hypokalemia | Downsloping ST depression with T-wave flattening or inversion and prominent U waves with increased QU interval. |
| RVH, RBBB | ST depression and T-wave inversion in V1-V3. |
QT interval
| Condition | EKG changes |
|---|---|
| Normal | Varies with heart rate and so corrected QTc is used- A common way to correct it is using Bazett formula (QTC = QT / √ RR). QTC is usually 0.35-0.44 seconds in men and 0.35-0.46 seconds in women. |
| Drugs: Class IA, IC, and III antiarrhythmics, Antipsychotics, Antiemetics, Tricyclic antidepressants, azaleas like fluconazole, antibiotics such as floroquinolones and macrocodes, etc. Hypokalemia/ Hypomagnesemia/ Hypocalcemia Myocardial Ischemia Hypothermia Raised ICT Congenital long QT syndromes | Long QTC |
| Congenital Short QT syndromes Digoxin Hypercalcemia | Short QTC |
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