Postprandial hypoglycemia in an infant associated with propranolol

Outcomes of Infant Supraventricular Tachycardia Management Without Medication

Most infants presenting with supraventricular tachycardia (SVT) are treated with an antiarrhythmic, primarily to prevent unrecognized future episodes that could lead to tachycardia-induced cardiomyopathy. A common practice at our institution is to not treat after the first presentation of infant SVT and instead educate parents on heart rate monitoring and reasons to present to care. The goal of this study was to evaluate the outcomes of non-pharmacologic treatment of infant SVT at first presentation and compare to outcomes of infants treated with an antiarrhythmic. This was a retrospective single center study of all infants presenting with a first episode of SVT from 2014 to 2021. Excluded were patients with a non-reentry type tachyarrhythmia, atrial flutter, long-RP tachycardia, congenital heart disease, or abnormal ventricular function. Sixty-four infants were included in the study. Thirty-six were managed without an antiarrhythmic. SVT recurred in 28% of the non-treatment group vs 50% in those treated with antiarrhythmics, p = 0.12. Of the patients admitted to the hospital, those in the non-treatment group had a shorter length of stay, 1(IQR 1-1) vs 3(IQR 2-4) days, p < 0.01. Non-treated patients were less likely to present to the emergency department for recurrent SVT, 6% vs 32%, p < 0.01. Neither group had a patient develop tachycardia-induced cardiomyopathy. For infants with structurally and functionally normal hearts, non-treatment combined with parental education after the first episode of SVT does not lead to worse outcomes. This approach avoids the burden of medication administration in an infant and may have the added benefit of empowering parents to feel comfortable managing clinically insignificant tachycardia at home.

Frequency and severity of hypoglycemia in children with beta-blocker-treated long QT syndrome

BACKGROUND

Hypoglycemia is a potential side effect of beta-blockers; however, no cases have been reported in children with long QT syndrome (LQTS).

OBJECTIVE

The purpose of this study was to determine the frequency and severity of hypoglycemia among children with beta-blocker-treated LQTS.

METHODS

A retrospective study was performed to identify children with LQTS evaluated from 2000 to 2014 who developed symptomatic hypoglycemia while being treated with a beta-blocker.

RESULTS

Nine children (3%; 7 boys; average corrected QT interval 486 ± 35 ms) developed 13 episodes (0.005 events per 100 treatment years) of beta-blocker-associated hypoglycemia (mean initial glucose 21 ± 7 mg/dL), including 3 of 157 patients with LQTS type 1 (LQT1; 1.9%) and 6 of 105 with LQTS type 2 (LQT2; 5.7%). The mean age at hypoglycemic event was 3.5 ± 2 years (range 7 months to 9 years), involving nadolol in 6 cases (mean dose 1.4 ± 0.2 mg/kg/d) and propranolol in 3 (mean dose 2.7±1 mg/kg/d). Hypoglycemic events were more frequent in patients with LQT2 than in those with LQT1 (10 vs. 3 events; P = .02). Hypoglycemia-triggered seizures were observed in 6 patients, fasting ketoacidosis in 5, and 7 patients required hospitalization (mean of 3 ± 2 days). Decreased caloric intake before the event was identified in all patients and a concomitant viral infection in 3.

CONCLUSION

This is the largest single-center case series of beta-blocker-induced hypoglycemia. Clinicians should be cognizant of hypoglycemia symptoms in younger children during periods of poor appetite and during viral illness, and parents of these children should be educated about the signs and symptoms of hypoglycemia. A potential LQT2-hypoglycemia genotype-phenotype relationship warrants further investigation.

Relative toxicity of beta blockers in overdose

OBJECTIVE

To compare the toxicity of beta blockers in overdose and to identify clinical features predictive of serious toxicity.

DESIGN

Comparison of clinical data collected prospectively on a relational database of subjects presenting to hospital with self-poisoning, coroner's data and prescription data.

SETTING

Newcastle and Lake Macquarie, Australia, 1987-1995.

MAIN OUTCOME MEASURES

Death, seizure, cardiovascular collapse, hypoglycemia, coma and respiratory depression.

SUBJECTS

Fifty-eight self-poisonings with beta blockers and two deaths investigated by the coroner with evidence of propranolol poisoning.

RESULTS

All patients who developed toxicity did so within six hours of ingestion. The use of ipecac was temporally associated with cardiorespiratory arrest in one patient. Propranolol was the only beta blocker associated with seizure; of those who ingested more than 2 g of propranolol, two thirds had a seizure. There was a significant association between a QRS duration of > 100 ms and risk of seizures. Propranolol was over represented in beta blocker poisoning when prescription data were also examined. Propranolol was the only beta blocker associated with death. Propranolol was taken by a younger age group.

CONCLUSIONS

Propranolol should be avoided in patients at risk of self-poisoning. Propranolol poisonings should be observed closely for the first six hours post ingestion. Syrup of ipecac should not be used to decontaminate the gastrointestinal tract after beta blocker overdose.