PHYS30001 Lecture Notes - Lecture 21: Tachycardia, Hypertrophy, Cardiac Arrhythmia
Document Summary
Re-entry circuit ( rhythm/dysrhythm): unidirectional conduction block produces tachyarrhythmia. Combination of digitalis and hypertrophy: prone to developing ectopic beats in ventricle. Might die out if there is enough refractory tissue, but could also turn into an inappropriate whole heart contraction. Cardio page 5 if route forward (orthograde) is blocked but route reverse (retrograde) is not, is a bit tricky if reverse conduction is relatively fast, still ok as route is refractory and signal dies out. But if route reverse (retrograde) is slowed, then there is trouble by the time signal gets back to branch x", route is ready to go again, and re-entry circuit is set up. To produce a conduction re-entry arrhythmia" need two conditions: a branch point and a partial blockage in one of the branches involving slowed conduction in one direction. From the re-entry circuit, the arrhythmic activity spreads throughout the electrical syncytium of the myocardial tissue.
