Role of sodium in contrast medium-induced polymorphic ventricular tachycardia: results in a rabbit model of lengthened QT interval.
OBJECTIVE
The authors (a) compared the proarrhythmic effects of ioxaglate (152 mmol/L sodium) and iohexol (no sodium) in a rabbit model and (b) assessed the effect of adding 150 mmol/L sodium to isotonic iohexol.


METHODS
Either ioxaglate (320 mg of iodine per milliliter) or iohexol (350 mg of iodine per milliliter) was selectively injected into the right coronary artery (1.5 mL over 30 seconds) of 10 rabbits, some of which also received the alpha 1-adrenergic receptor agonist methoxamine. To validate the model, the class III antiarrhythmic agent clofilium was injected intravenously during methoxamine infusion. Frontal electrocardiography was performed continuously to detect polymorphic ventricular tachycardia (PVT). In a second study, the authors assessed the frequency of arrhythmias after injection of isotonic iohexol solution (145 mg of iodine per milliliter), either alone or with 150 mmol/L sodium.


RESULTS
Methoxamine significantly lengthened the QT, QTc, and RR intervals (P < .05). The use of clofilium alone induced no PVT, whereas five of eight methoxamine-infused rabbits developed PVT after clofilium injection (P = .03). Both contrast media prolonged the repolarization period. Iohexol alone induced a higher frequency of PVT than did ioxaglate alone (P = .0006). Methoxamine infusion did not potentiate the frequency of PVT in the ioxaglate-injected rabbits. The addition of sodium to isotonic iohexol prevented the occurrence of PVT (P = .0006).


CONCLUSIONS
Although ioxaglate prolonged the repolarization period, it did not cause a higher frequency of arrhythmia when injected in association with methoxamine. Iohexol, which contains no sodium, induced a high frequency of arrhythmia. The addition of a physiologic concentration of sodium to isotonic iohexol can prevent ventricular arrhythmias.
Idée
J M
JM
Department of Pharmacology, Laboratoire Guerbet, Roissy-Charles-de-Gaulle, Aulnay-sous-Bois, France.
Bourgoin-Balut
C
C
Lefevre
T
T
Zamia
P
P
Goulas
V
V
Gaillard
S
S
Mathias
C
C
Bonnemain
B
B
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D003287:Contrast Media / Q000494:pharmacology*; D017023:Coronary Angiography / Q000009:adverse effects; D003331:Coronary Vessels / Q000187:drug effects; D004195:Disease Models, Animal; D004347:Drug Interactions; D004562:Electrocardiography / Q000187:drug effects*; D007262:Infusions, Intravenous; D007472:Iohexol / Q000494:pharmacology; D007485:Ioxaglic Acid / Q000494:pharmacology*; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D011817:Rabbits; D012964:Sodium / Q000502:physiology*; D017180:Tachycardia, Ventricular / Q000139:chemically induced / Q000503:physiopathology / Q000517:prevention & control*
D000316:Adrenergic alpha-Agonists; D000889:Anti-Arrhythmia Agents; D003287:Contrast Media; D000644:Quaternary Ammonium Compounds; D007472:Iohexol; C022799:clofilium; D012964:Sodium; D008729:Methoxamine; D007485:Ioxaglic Acid