How to explain the effect of hypo/hyper kalemia, calcemia and natremia on nerve excitability and heart excitability

how to explain the effect of hypo/hyper kalemia, calcemia and natremia on nerve excitability and heart excitability

Bundle Branch Block (BBB) and ventricular tachycardia (VT) are two different cardiac electrical conduction abnormalities that can be observed on an electrocardiogram (ECG). The patterns you mentioned - the “M pattern” or “bunny ears” appearance in BBB and the asymmetrical “bunny ears” in VT - have distinct characteristics based on the underlying mechanisms of each condition.

  1. Bundle Branch Block (BBB):
  • In BBB, the “bunny ears” or “M pattern” appearance on the ECG is due to a delay or blockage in the electrical conduction through one of the bundle branches (left or right) in the heart.
  • The delay in conduction causes the electrical signal to take a longer route to reach certain areas of the ventricles, resulting in a characteristic widened QRS complex on the ECG.
  • The “bunny ears” or “M pattern” occurs because the delayed activation of the ventricles causes two separate depolarization waves - one for the initial activation of the unaffected ventricle and another for the delayed activation of the affected ventricle.
  1. Ventricular Tachycardia (VT):
  • Ventricular tachycardia is a rapid, abnormal heart rhythm originating in the ventricles, often associated with serious cardiac conditions.
  • The appearance of an asymmetrical “bunny ears” pattern in VT on the ECG is due to the abnormal, rapid, and uncoordinated electrical activity within the ventricles during VT.
  • The irregular and rapid electrical signals cause an irregular and widened QRS complex, resulting in the asymmetrical “bunny ears” appearance.

In summary, the “bunny ears” appearance is observed in both BBB and VT, but the asymmetry in the “bunny ears” in VT is due to the irregular and rapid electrical activity originating from the ventricles during tachycardia, whereas the “M pattern” in BBB is due to the delayed and separate activation of the ventricles caused by bundle branch block.