Where to Q in PEP
Related Experiment Video
Updated: Aug 25, 2026

Network Pharmacology and Validation of the Antidepressant Mechanisms of Qiangzhifang in a Chronic Restraint Stress-induced Depression Rat Model
Published on: June 6, 2025
Gary G Berntson1, David L Lozano, Yun-Ju Chen
1Department of Psychology, The Ohio State University, Columbus, Ohio 43210, USA. Berntson@osu.edu
Abstract:
The onset of ventricular depolarization defines the start of the preejection period (PEP), which is commonly used as an index of myocardial contractility and sympathetic control of the heart. Although the fiducial point for this onset has traditionally been the onset of the Q wave of the electrocardiogram, other measurement points have also been used in the literature, including the peak of the Q wave (i.e., the onset of the R wave). Conceptual, physiological, and empirical considerations addressing the reliability and validity of these alternative metrics support the application of the Q-wave peak/R-wave onset as the fiducial point for PEP measures.
More Related Videos
07:30A Novel Behavioral Assay to Investigate Gustatory Responses of Individual, Freely-moving Bumble Bees (Bombus terrestris)
Published on: July 21, 2016
05:20Determination of 45 Pesticides in Avocado Varieties by the QuEChERS Method and Gas Chromatography-Tandem Mass Spectrometry
Published on: December 8, 2023
Related Concept Videos
Quartile
1; 1; 2; 2; 4; 6; 6.8; 7.2; 8; 8.3; 9; 10; 10; 11.5
The median or second quartile is seven. The lower half of the...
Le Chatelier's Principle: Changing Concentration
Free Energy Changes for Nonstandard States
Detection of Gross Error: The Q Test
Titration Calculations: Weak Acid - Strong Base
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
Free Energy and Equilibrium
Recall that Q is the numerical value of the mass action expression...