Persistent supraventricular tachycardia following infusion with ritodrine hydrochloride

Supraventricular tachycardia in pregnancy

We present four cases of supraventricular tachycardia in pregnancy of varied aetiology. Risk factors for the development of supraventricular tachycardia and options for obstetric anaesthetic management, during pregnancy, labour, and at Caesarean section are discussed. We recommend the use of adenosine as first line therapy.

Awaiting cervical change for the diagnosis of preterm labor does not compromise the efficacy of ritodrine tocolysis

We retrospectively studied 209 patients treated with ritodrine hydrochloride to determine whether change in cervical effacement or dilatation during a period of observation before therapy would result in decreased efficacy of ritodrine, as measured by delivery delays of 48 hours, 1 week, or until greater than or equal to 37 weeks' gestation; neonatal intensive care unit admission; and neonatal respiratory distress syndrome. Patients who were greater than or equal to 3 cm dilated on admission were at high risk of therapy failure by all outcome measures compared with patients less than 3 cm dilated. For patients less than 3 cm dilated on admission, there was no difference in outcome when patients treated for contractions only were compared with those treated after change in effacement or dilatation had been documented. We conclude that awaiting change in cervical effacement or dilatation to be more certain of the diagnosis of preterm labor will not compromise the efficacy of ritodrine tocolysis.

Transient electrocardiographic changes suggesting myocardial ischaemia in newborn infants following tocolysis with beta-sympathomimetics

Serial electrocardiograms (ECGs) were studied prospectively in 80 apparently healthy newborn infants; 30 infants exposed in utero to prolonged tocolytic therapy (21 to ritodrine and 9 to isoxsuprine) and 50 infants non-exposed in utero to drugs (control group) matched for gestational age, Apgar score, and birth weight. Duration of exposure to tocolysis was at least 30 days (30-180 days) with an oral dosage of 10 mg 3 times daily. ECGs were graded for changes suggestive of ischaemia using the arbitrary grading system described by Jedeikin et al. In all infants with ECG features of myocardial ischaemia, serum creatine-phosphokinase iso-enzyme (CK-MB) activity was measured. Six out of 21 infants to ritodrine and six out of nine infants exposed to isoxsuprine showed a degree of ECG ischaemia which persisted for several weeks. No control infant presented grade 2 or 3 ECG changes after the 5th day of life. The results of this study seem to show that prolonged tocolytic therapy with beta-sympathomimetics has side-effects on the fetal myocardium and suggest that this treatment be reserved only for selective cases and/or for short periods of time.

A glycopyrrolate-ritodrine drug-drug interaction

This is a case report of a 39-year-old patient who developed supraventricular tachycardia secondary to a ritodrine-glycopyrrolate interaction. The cardiovascular effects of ritodrine as well as the possible mechanism for this interaction are discussed. Suggested treatment for ritodrine-induced tachycardia in the parturient are presented.

Ritodrine-induced pulmonary oedema in labour. Successful management using epidural anaesthesia

A case is described in which unusually high doses of intravenous ritodrine were used for 6 weeks to postpone premature labour. Treatment was complicated by tachydysrhythmias and pulmonary oedema. Epidural analgesia was used successfully for pain relief during labour and Caesarean section. The pathophysiology is discussed.