Electrocardiographic Measurements of the QT Interval During Embryonic Development in Fertilized Chicken Eggs

Abstract

The fertilized chicken egg (embryonic chicken) IntroductionThe ionic basis of the chick embryonic action potential is similar to the most vertebrate hearts and studies of chick embryonic ion channels show that the permeability to K+ increases during the embryonic period [1]. Potassium channels are responsible for the repolarization process and any change in K+ permeability may have an effect on the electrocardiographic QT interval. Changes in ion channel permeability may also greatly affect the responsiveness of the myocardium to pharmacological agents.In this study we have recorded in vivo electrocardiograms from fertilized chicken eggs to investigate the association between embryonic development and the duration of the QT interval. Methods Study populationECGs were recorded from 4 fertilized chicken eggs for 6 days. Between recordings, the fertilized eggs were kept in an incubator with a temperature of 37.4°C. Electrode implantationGold plated chronic electrodes were used. The position of the embryo was confirmed prior to electrode placement by setting the egg against strong coherent light. The electrodes were cleaned in 80% alcohol solution to prevent bacterial formation. Three tiny holes were made with sterile needles and the electrodes were inserted at the equatorial region of the eggs 120 0 apart from each other. The two electrodes placed with the embryo in between them were connected to differential inputs and the third electrode was connected to the ground of the iWorx system (iWorx TM ). After the implantation, the holes were immediately closed with acrylic cement and the egg was put back in the incubator. ECG recordingsContinuous 5-minute ECGs were recorded from each egg on days: 13,14,15,16 and 18. A high pass filter (cutoff frequency = 1 Hz) was used to remove baseline drift and a 15-tap moving average filter was used to smooth the ECG signal. Three measurements were made in noise free segments: Heart rate, QT interval, and the Fridericia corrected QT interval (QTcF), and an average value was calculated. A 10 second segment of a representative ECG recording is shown in figure 1.

Exercise‐related hypoglycaemia induces QTc‐interval prolongation in individuals with type 1 diabetes

“…In addition to QTc interval, we assessed changes in Tpe interval and T-wave amplitude, which are less rate-dependent risk markers for arrhythmia. [32][33][34] Tpe interval is a marker for transmural dispersion of repolarisation, where prolongation may increase vulnerability to ventricular arrhythmias. 33,35 We detected a prolonged Tpe interval of The present study has some limitations.…”