HIS Bundle electrocardiogram
Programmed electrical stimulation (abbreviated EPS for electrophysiologic studies eq – HIS bundle electrocardiogram) has added a new dimension to the treatment of arrhythmias. Before the introduction of EPS, a patient with an arrhythmia requiring treatment was given a drug empirically, and after several days, when therapeutic levels had been achieved, a 24-hour Holter monitor would be used to see whether the frequency of the arrhythmia had been reduced.
EPS is not necessary for all patients with arrhythmias, and Holter monitor remains the IOC of arrhythmia diagnosis and treatment. EPS is expensive and invasive, but for certain patients it has great value, greatly refining the process of choosing the right drug for patients who need rapid and effective therapy.
- HIS bundle electrocardiogram is done in patients with heart block, the electrical events in the AV node, bundle of His, and Purkinje system are frequently studied with a catheter containing an electrode at its tip that is passed through a vein to the right side of the heart and manipulated into a position close to the tricuspid valve.
- The record of the electrical activity obtained with the catheter is the His bundle electrogram (HBE).
- Three or more standard electrocardiographic leads are recorded simultaneously.
- Three deflection (wave) in HBE are:
- A deflection when the AV node is activated,
- H spike during transmission through the His bundle
- V deflection during ventricular depolarization.
Comparing the 3 deflections with HBE with standard ECG
- PA interval: Time from first appearance of P wave of standard ECG to A wave in HBE, which represents conduction time from SA node to AV node.
- AH interval: From A wave to the start of H spike, which represents AV nodal conduction time.
- HV interval: Time from the start of H spike to the start of QRS deflection in the standard ECG, which represents conduction in bundle of His and bundle branches.
The approximate normal values for these intervals in adults are PA= 27 ms; AH = 92 ms (normal = 60 to 125 ms); and HV, 43 ms (normal = 35 to 55 ms).
MCQ on HIS Bundle electrocardiogram