The evaluation and management of drug effects on cardiac conduction (PR and QRS Intervals) in clinical development

The PR interval and QRS duration could be predictors of renal function decline

“…The dQRS is the time from the beginning of the first deflection to the end of the last deflection and indicates activation of ventricular myocardium [15]. Cheng et al [6] showed that both autonomic and structural cardiac abnormalities might lead to prolongation of iPR.…”

“…The iPR includes both atrial activation (P wave) and the time for conduction through the AV node in the AV junction, and then through the specialized His-Purkinje conduction system to the ventricles simultaneously via the bundle branches [15]. The dQRS is the time from the beginning of the first deflection to the end of the last deflection and indicates activation of ventricular myocardium [15].…”

QRS interval: What is it? How to measure it?

“…Figure And no heart rate influence on QRS duration relationship was observed during exercise in the control group of a flecainide study (18). Because digital signal is a discontinuous representation of a continuous phenomenon (even though propagation is a discontinuous phenomenon (8)), sampling rate is a key issue in quantitative electrocardiography (14,19). From a theoretical stand point, obtaining a result of a magnitude below the limit of resolution according to sampling rate can be considered as questionable.…”

“…When it is about quantitative electrocardiology, evil is often in the methodological details. Some of the pitfalls in the Mason et al article have already been addressed by the accompanying editorial (6).The 2009 AHA/ACCF/HRS recommendations(14) as well as the CSRC White paper(19) have reviewed technical issues arising when measuring the QRS duration.…”

Evaluation of Melissa officinalis (Lemon Balm) effects on heart electrical system

“…Hypertrophic or infiltrative diseases, drugs or focal damage from infarction may be associated with prolonged QRS (19). Sodium channel blockers including some class IA or 1C antiarrhythmics by blocking inward sodium current, can slow depolarization, reduce conduction velocity, prolong the QRS interval and consequently it may increase the risk of arrhythmia (19,21). Inward rectifier potassium channel blockers such as chloroquine cause a more positive resting membrane potential, par-tial inactivation of sodium channels and hence can prolong the QRS interval (22).…”