[Heart-specific L-myosin in pregnancy and tocolysis therapy]

Determination of light-chain (L-)myosin represents the currently most sensitive and specific method for detection of myocardial damage, which often was reported during tocolysis with betamimetics. Compared with 51 healthy pregnant subjects, it was not possible to demonstrate any pathologic increase in 14 patients, who underwent a tocolytic treatment with ritodrine-verapamil.

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.

Dilemmas in the pharmacological management of preterm labor

It is the thesis of the author that the use of Ritodrine in the treatment of premature labor is potentially dangerous and possibly even lethal. Ritodrine is being overused in the attempt to control and delay premature labor. Only 25 to 50 per cent of patients complaining of premature labor pains actually proceed to true preterm labor. Because there is no definitive screening test to firmly establish the diagnosis of preterm labor, many women are treated unnecessarily with a drug that many obstetricians question as to its efficacy, safety, and cost. If it is used, it must be in a hospital with adequate facilities both in manpower and the ability to identify and treat the medical and obstetrical complications. Ritodrine is too potentially dangerous to be used as an attempt to "do something" it there are questionable indications.

Asthma in pregnancy complicated by iatrogenic pulmonary oedema

We report a unique case of near fatal acute pulmonary oedema developing with intravenous ritodrine, given in an attempt to suppress premature labour. The novel aspect of the case is that the patient had also been treated in the previous week with high dose nebulized beta-agonists for an episode of acute severe asthma, demonstrating that this idiosyncratic reaction to beta-adrenergic agents only occurs with the intravenous route of administration. The management of acute severe asthma occurring in pregnancy is discussed with a review of previous literature regarding possible mechanisms of beta 2-agonist-induced pulmonary oedema.

Umbilical cord prolapse: a true obstetrical emergency

The case of a 23-year-old woman with umbilical cord prolapse and fetal distress is described. This serious obstetrical complication is unfamiliar to many emergency physicians although it represents an acute emergency with high mortality. Appropriate prehospital, emergency department, and obstetrical suite care is discussed including a bladder-filling technique and tocolysis that can buy valuable time by temporarily relieving pressure on the cord.

Randomized comparison of oral terbutaline and ritodrine for preventing recurrent preterm labor

We compared oral ritodrine and terbutaline for the prevention of recurrent preterm labor. Women between 20 and 35 weeks' gestation who successfully completed a course of intravenous tocolysis were eligible for inclusion. One hundred two patients were randomized to oral ritodrine (20 mg every four hours) or oral terbutaline (5 mg every four hours). The groups showed no significant differences with respect to recognized risk factors for preterm labor or prognostic factors for the failure of tocolysis. Initial treatment failures occurred more frequently in the ritodrine group (nine vs. two, P = .0527). There were no statistically significant differences in the treatment results or frequency of side effects. We conclude that ritodrine appears to be less effective than terbutaline upon the initiation of oral therapy and that oral ritodrine and terbutaline are equivalent in safety and efficacy when used on a long-term basis for preventing recurrent preterm labor.

Acute pulmonary edema associated with the use of oral ritodrine for premature labor

We describe a patient who developed acute pulmonary edema while taking oral ritodrine for the treatment of premature labor and recovered after its discontinuation. The mechanism of development of pulmonary edema associated with beta-sympathomimetic agents is still not fully understood. Patients taking oral ritodrine should be observed for cardiopulmonary signs and symptoms.

Efficacy and side effects of magnesium sulfate and ritodrine as tocolytic agents

Ritodrine as the first-line drug in the treatment of established preterm labor has been supplanted in some centers by magnesium sulfate. To assess the relative efficacy and rates of side effects of these two agents, 120 patients were randomly assigned to receive one of these two drugs. Patients were included if they had intact membranes and met strict criteria for the definition of labor. In both groups excellent outcome was achieved, with 96.3% and 92.3% of patients receiving ritodrine and magnesium sulfate, respectively, obtaining a delay in delivery of greater than 48 hours. Side effects were comparable in both groups, although they tended to be more serious in the patients receiving ritodrine. In patients receiving both drugs together, the rate of side effects was 77% without a demonstrable benefit over a single agent. We conclude that ritodrine and magnesium sulfate are tocolytics of comparable efficacy and when used aggressively are highly successful in delaying delivery.

ST segment depression in paired electrocardiograms and serum electrolytes in pregnant women receiving intravenous ritodrine

Forty-three women admitted for preterm labor had electrocardiograms and serum potassium and glucose levels determined before and two and four hours after the initiation of intravenous ritodrine tocolysis. The ST segment depression found at two and four hours was significant but not dependent upon a fall in potassium or increase in the heart rate or glucose level. Such symptoms as chest pain and dyspnea were also not dependent upon potassium, glucose or heart rate changes. These findings support the concept of an intrinsic drug effect.

Pharmacodynamics and tolerance of oral sustained release ritodrine

A new oral sustained release formulation of ritodrine was tested for patient tolerance in this open study. The doses tested were 120 mg/day, 240 mg/day, and 360 mg/day. No objective toxicity was seen at any level. Doses of 120 mg/day and 240 mg/day were well-tolerated. Of the subjects who received the 360 mg/day dose, most tolerated it well.

Ritodrine-induced pulmonary edema unmasking underlying peripartum cardiomyopathy

Pulmonary edema was induced by an increase in the dose of ritodrine in a patient receiving the drug for 28 days because of preterm contractions. After initial therapy, the cardiologic evaluation revealed peripartum cardiomyopathy. This is the first report of ritodrine causing pulmonary edema by unmasking underlying asymptomatic cardiomyopathy. This may have been the cause of some of the previously reported cases of ritodrine-induced heart failure.

Anaesthesia for caesarean section in a parturient with quintuplet gestation, pulmonary oedema and thrombocytopaenia

The case of a 32-year-old parturient with a quintuplet pregnancy is described. The pregnancy had been complicated by premature labour which was treated with ritodrine tocolysis. Betamethasone was administered to hasten fetal lung maturation. The ritodrine therapy was complicated with fluid overload and pulmonary oedema requiring intravenous diuretic treatment. The patient presented urgently for Caesarean section, with fluid overload and worsening thrombocytopaenia. Life-threatening pulmonary oedema was manifest in the immediate preinduction period, following insertion of a pulmonary artery catheter and surgery was delayed to improve the mother's condition with intravenous diuretic therapy. Induction was carried out with the patient in the sitting position, with cricoid pressure maintained to protect the airway as the patient was lowered to a wedged, supine position. Intravenous nitroglycerin was used to control blood pressure. Low pressure mask-bag ventilation was utilized to maintain oxygen saturation and the patient was intubated and ventilated with positive end-expiratory pressure. Positive pressure ventilation was continued for 24 hours postoperatively. The perioperative course is reviewed and followed by a discussion of the anaesthetic considerations for multiple gestation pregnancies.

Comparison of oral ritodrine and magnesium gluconate for ambulatory tocolysis

Magnesium sulfate has been administered intravenously to arrest preterm labor but the oral form of this drug cannot be used for continual tocolysis. This trial involved the administration of oral magnesium gluconate to determine its effectiveness compared with that of ritodrine hydrochloride in 50 patients whose labor had been arrested by parenteral therapy. Group A (n = 25) received 1 gm of oral magnesium gluconate every 2 to 4 hours for tocolysis and group B (n = 25) received 10 mg of ritodrine every 2 to 4 hours. The number of patients who progressed to 37 weeks' gestation was similar (group A, 21 versus group B, 19) and the time gained in utero was not different (group A, 6.4 weeks versus group B, 5.9 weeks). There was a trend toward more side effects with the use of ritodrine (40%) compared with magnesium gluconate (16%), but the numbers were too small to reveal a significant difference. These data suggest that magnesium gluconate used as an oral tocolytic is as effective as a beta-agonist in patients whose labor is arrested initially with intravenous therapy.

Ventricular tachyarrhythmias during cesarean section after ritodrine therapy: interaction with anesthetics

This case illustrates that patients receiving ritodrine for preterm labor may risk interactions between the residual betamimetic effects of ritodrine and the effects of anesthetics during cesarean section. Such interactions may result in serious cardiovascular complications even after cessation of an infusion of ritodrine. Preoperative assessment should focus on cardiovascular status and serum potassium level. Delaying induction of anesthesia should be considered whenever possible. Careful fluid administration and cautious use of titrated doses of ephedrine are advised. After delivery of the infant, there should be no contraindication to the use of an alpha-adrenergic vasopressor such as phenylephrine to treat hypotensive patients with tachycardia.

Detection of cardiac events by continuous electrocardiogram monitoring during ritodrine infusion

Cardiac events in 30 patients in preterm labor on ritodrine therapy were examined continuously on a Holter monitor. Unsuspected events, such as persistent severe tachycardia, premature ventricular contractions, and supraventricular premature contractions, were observed. These events did not occur more frequently in patients with cardiac symptoms. None of these changes were observed by standard monitoring methods. Continued beta-mimetic stimulation in the presence of these events may lead to the serious cardiopulmonary complications that have been reported during ritodrine infusion.

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.

Intravenous ritodrine as a possibly provocative predictive test in gestational diabetes. A case report

A 24-year-old, nonobese, gestational diabetic woman developed diabetic ketoacidosis while receiving intravenous ritodrine therapy to suppress premature labor. This case emphasizes the necessity for close observation of any gestational diabetic during intravenous ritodrine tocolysis and suggests the possibility of predicting diabetes in pregnant patients exhibiting marked glucose intolerance during therapy.

Peripartum congestive cardiomyopathy and endocardial fibroelastosis associated with ritodrine treatment. A case report

Congestive cardiomyopathy from endocardial fibroelastosis occurred in a 24-year-old primigravida with a twin gestation and preeclampsia. The patient was taking ritodrine for premature labor. Cardiovascular evaluation should be performed during the course of ritodrine treatment, and no patient should be discharged if she does not have normal cardiovascular function.

Fasting hyperinsulinemic hypoglycemia after ritodrine therapy for premature labor

A 26-year-old woman with a triplet pregnancy was treated prophylactically with ritodrine beginning at 15 weeks' gestation. At 32 weeks, she was admitted in preterm labor, and over the next 12 days received high-dose oral or intravenous ritodrine. Three female infants were delivered by cesarean section after spontaneous rupture of the membranes. Postoperatively, she developed profound hypoglycemia with inappropriately high insulin levels. Maternal hypoglycemia after ritodrine therapy in pregnancy has not been reported previously. We discuss possible mechanisms.

Pulmonary edema as a delayed complication of ritodrine therapy. A case report

Pulmonary edema occurred 24 hours after intravenous ritodrine therapy and 10 hours after subcutaneous terbutaline therapy. Standard therapy directed at volume overload quickly cleared the pulmonary congestion, and the pregnancy progressed uneventfully to term. A retrospective review incriminated transfusion therapy and volume overload as the etiology.