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KMID : 0352519870240010499
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Korea Univercity Medical Journal
1987 Volume.24 No. 1 p.499 ~ p.507
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Cardiac Anomalies, Hemodynamic Changes and Histologic Changes induced by Electrical Shocks to the Conotruncus of the Embryonic Chick
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Abstract
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Electrical shock stimulation of the conotruncal area induced a spectrum of Double outlet right ventricle (DORV) in embryonic chicks at developmental stages 24-27. The device used to apply electrical potentials to the heart was constructed using a 9 volt battery, a push-botton switch, and a 100 ohm, ten-turn potentiometer with a calibrated dial. The potentiometer was connected as a voltage divider with the outlet connected to an electrode pair. This allowed for a short voltage pulse (variable 0 to 9 volts) to be applied to a selected area of the heart through the electrodes. Two different methods were chosen to apply electrical shocks to the conotruncal area of the heart. One method utilized the application of an electrical shock between two points across the Conotruncus of cardiac loop (horizontally oriented) and the second method between two points along the Conotruncus of cardiac loop (vertically oriented).
The range of voltages applied to the conotruncal area of the heart was from 2 to 4 volts. Soon after electrical shock, continuous wave Doppler was applied for evaluation of the flow pattern at the level of the Conotruncus. Three distinct types of double outlet right ventricles were in the longitudinal(L) and horizontal(H) electrical shock groups:
1) A double outlet right ventricle (DORV) without a ventricular septal defect(VSD), which is associated with a prolapse of an aortic valve into the right ventricle (5/50 cases in L group, 3/40 cases in H group).
2) DORV with a subaortic VSD, with a variable degree of pulmonary stenosis and a hypoplastic left ventricle (20/50 cases in L gorup, 12/40 cases in H group).
3) DORV with a subpulmonary VSD and a pulmonary stenosis, with hypoplastic right ventricle (15/50 cases in L group, 5/40 cases in H group).
Longitudinal stimulation induced more cardiovascular anomalies than horizontal stimulation, and histological examination revealed the complete disappearance of the myocardial fibers, myocardial degeneration, and the aggregation of protein material or glycogen in the myocardial cells. After electrical shock, continuous wave Doppler pattern at the level of the Conotruncus demonstrated that increased peak velosity and low level of percent window (%).
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