Cardiac isoenzymes and electrocardiographic changes during ritodrine tocolysis.
To investigate the potential myocardial ischemic effects of ritodrine, we studied 36 singleton and four twin preterm pregnancies during ritodrine therapy. We serially determined serum creatinine phosphokinase (CPK-MB fraction) and lactic dehydrogenase isoenzymes and performed electrocardiography before and during ritodrine infusion and again within the first 24 hours of oral drug therapy. We observed that serum CPK-MB and lactic dehydrogenase isoenzymes remained within the normal range during therapy periods. The incidence of sinus tachycardia and non-specific T wave changes were 100% and 25%, respectively. In three of four twin pregnancies, ST-T segment depression in leads I, V4, V5, and V6 of the electrocardiogram was noted. Our study suggests that (1) the recommended ritodrine regimen does not produce direct myocardial damage, and (2) ritodrine may cause cardiac ischemia as determined by electrocardiography, which theoretically would progress to myocardial damage if not treated properly.
Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta.
H A
HA
Hadi
S J
SJ
Albazzaz
D004796:Clinical Enzyme Tests; D003327:Coronary Disease / Q000139:chemically induced / Q000175:diagnosis; D003402:Creatine Kinase / Q000097:blood*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000097:blood*; D009206:Myocardium / Q000201:enzymology*; D007752:Obstetric Labor, Premature / Q000175:diagnosis / Q000188:drug therapy; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000187:drug effects; D012312:Ritodrine / Q000008:administration & dosage* / Q000009:adverse effects; D013997:Time Factors; D015149:Tocolytic Agents; D014427:Twins
D007527:Isoenzymes; D015149:Tocolytic Agents; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase; D012312:Ritodrine