Mechanism of ECG changes and arrhythmogenic properties of low osmolality contrast media during coronary arteriography in dog.
OBJECTIVE
The aim of the study was to investigate the mechanisms behind ECG changes and ventricular arrhythmias during coronary arteriography.


METHODS
Transmembrane action potentials were recorded from isolated heart muscle preparations superfused with contrast media. Conductivity of plasma diluted with contrast media was determined in vitro. Epicardial ECG recordings were made during coronary arteriography.


METHODS
Epicardial ECG recordings were made in eight mongrel dogs of either sex, weight 14-22 kg. Atrial appendages were excised from the same dogs and used for heart muscle preparation studies.


RESULTS
Iohexol and ioxaglate affected the action potentials similarly: resting potential, amplitude, rate of depolarisation, and action potential duration increased; effective refractory period decreased. Both contrast media reduced plasma conductivity. During coronary arteriography both media increased R wave amplitude, depressed ST segment, and prolonged QT time on epicardial ECG.


CONCLUSIONS
ST segment deviation on ECG reflects hyperpolarization and increased amplitude of action potential rather than depolarisation consistent with ischaemia. Increased rate of depolarisation and amplitude of action potential together with reduced conductivity after contrast media may explain increased amplitude of QRS voltage on ECG. Observed regional changes in depolarisation, repolarisation, and refractoriness may be important in the genesis of ventricular arrhythmias.
Kløw
N E
NE
University of Tromsø, Norway.
Tande
P M
PM
Hevrøy
O
O
Refsum
H
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D017023:Coronary Angiography; D004285:Dogs; D004553:Electric Conductivity; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D007472:Iohexol / Q000494:pharmacology*; D007485:Ioxaglic Acid / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009994:Osmolar Concentration
D007472:Iohexol; D007485:Ioxaglic Acid