The P wave is the first positive deflection on the EKG and represents atrial depolarization. The first half represents right atrial depolarization and the second half represents left atrial depolarization.
✅ Axis: 0° to +75°.
✅ Amplitude (L leads): <2.5 mm.
✅ Amplitude (P leads): <1.5 mm.
✅ Duration: 0.08 - 0.11 sec.
✅ Morphology: Upright in I, II, aVF and inverted in aVR.
The impulse can travel backward, in a retrograde fashion, through the atria, producing a retrograde P wave, as long as the impulse penetrate the AV node and depolarize the atria.
2/ Focal atrial tachycardia is characterized by at least three or more consecutive ectopic P waves with similar morphology, usually arising from a single ectopic focus.
Possible causes: May be caused by morphological changes in the cardiomyocytes' action potential waveforms. Another causes include: Drugs (such as Dofetilide, Quinidine, Ranolazine, Verapamil), long QT syndrome, athletes, others.
✅ New STE ≥1 mm in all leads other than V2 or V3.
✅ New STE in V2-V3 ≥2 mm in men older than 40 years old and ≥2.5 mm in men younger than 40 years old or ≥1.5 mm in women.
1/ Let’s talk about PR Interval - Segment #CardioTwitter.
The PR interval represents the time between the onset of atrial depolarization and the onset of ventricular depolarization and reflects conduction through the AV node.
Acute pulmonary embolism (PE) is one of the most serious form of venous thromboembolism. The clinical presentation of PE is variable and often nonspecific making the diagnosis challenging.
✅ Sinus tachycardia (most common).
✅ S1Q3T3 pattern (may be present up to 30% of cases).
✅ Simultaneous T wave inversions in the inferior leads and right precordial leads can be seen.
✅ Right axis deviation.
✅ RBBB (complete or incomplete).