ECG

ECG in Hyperkalemia

Among the various electrolyte abnormalities, hyperkalemia, hypokalemia, hypercalcemia, and hypocalcemia are the only disorders that can cause reliable diagnostic changes in the electrocardiogram (ECG). These ECG changes can be recognized well before the results of the laboratory tests become available. The severity of these electrolyte abnormalities usually parallels the changes in the ECG. A simple rule to remember regarding the effect of these electrolyte abnormalities on the ECG is that when increased levels are present (hyperkalemia or hypercalcemia), the QT interval is shortened. Inversely, when decreased levels of these electrolytes are present (hypokalemia or hypocalcemia), the QT interval is prolonged. … Read more

Supraventricular Tachycardia

Supraventricular Tachycardia Introduction Tachycardia refers to a heart rate >100 beats per minute (bpm). The tachycardia may be supraventricular or ventricular depending on the origin of the arrhythmia. Supraventricular Tachycardia (SVT): If the tachycardia originates above the bifurcation of the bundle of His, usually in the atria or atrioventricular (AV) junction, the tachycardia is supraventricular. Supraventricular impulses follow the normal AV conduction system, activate the ventricles synchronously and will have narrow QRS complexes measuring <120 milliseconds. The QRS may be wide if there is pre-existent bundle branch block, ventricular aberration, or the impulse is conducted through a bypass tract. Ventricular … Read more

Right Bundle Branch Block (RBBB)

Right Bundle Branch Block or RBBB is a delay or block of conduction within the right bundle branch. In complete RBBB, the duration of QRS is >120ms and in incomplete RBBB it is between 100 and 120ms.

Basic Principles of Arrhythmogenesis

Arrhythmogenesis means genesis of abnormal rhythm of the heart i.e, arrhythmias. Arrhythmias means irregular heart beat. Atrial Fibrillation, Atrial flutter, Some pacemaker requiring abnormal ventricular rhythms are some of the examples of arrhythmias. Basic Principles of Arrhythmogenesis Determination of Heart Rate If RR interval or PP interval is less than three large squares, then the rate is over 100 per minute and connotes a tachycardia. If the RR or PP interval is more than five large squares, then the rate is less than 60 per minute and connotes bradycardia. Anatomy and Physiology of conducting system The rate and rhythm of … Read more