Bundle of His vs. Purkinje Fibres: Key Differences in Cardiac Conduction
The Bundle of His is a thick, fast-conducting tract that exits the AV node and splits into bundle branches, while Purkinje Fibres are delicate, terminal filaments that sprout from those branches and deliver electricity to ventricular muscle.
Students and clinicians often swap the names because both structures sit “after the AV node” and “before the ventricles,” making them feel like one long highway rather than distinct relay stages.
Key Differences
Bundle of His: 2 cm, insulated, runs inside the interventricular septum, transmits impulses to the bundle branches. Purkinje Fibres: spider-web array, lack myelin, spread the signal across ventricular endocardium within 0.03 s.
Which One Should You Choose?
Choose Bundle of His when discussing AV conduction blocks; pick Purkinje Fibres when mapping ventricular arrhythmias or assessing pacing thresholds.
Examples and Daily Life
On an ECG, a prolonged PR without wide QRS points to Bundle of His disease; premature, wide, bizarre QRS complexes hint at ectopic Purkinje Fibre firing.
Can either structure generate its own rhythm?
Yes; Purkinje Fibres can fire at 20–40 bpm as a ventricular escape if higher pacemakers fail.
Which is more vulnerable to ischemia?
Purkinje Fibres, because they lie closer to the endocardial surface and receive blood last.