A case of long QT syndrome: challenges on a bumpy road

Salbutamol-Induced QT Interval Prolongation in a Two-Year-Old Patient

Salbutamol-induced QT interval prolongation is a relatively rare adverse effect of beta2-agonists. We report a case of a two-year-old female patient with no known past medical history, brought by her parents to the ED 30 minutes after ingesting a total dose of 97 mg of salbutamol solution. ECG was done for the patient when she arrived and showed sinus tachycardia with prolonged QTc (509 ms) and normal QRS complex. The patient was admitted to the Pediatric Intensive Care Unit (PICU) with persistent tachycardia and tachypnea in the initial reassessment. ECG was repeated with normal QT interval after IV Mg sulfate. The patient was observed in PICU for 12 hours with serial ECG and venous blood gas (VBG). IV potassium chloride (KCL) infusion started, and serial VBG showed normal potassium and lactate. The patient was doing well in the next six hours, with normal serial ECG, labs, and vital signs.

In conclusion, salbutamol-induced QT prolongation has infrequently been reported in the literature. Although inhaled salbutamol is commonly used in clinical practice, physicians have limited experience with the severe features of its toxicity. Salbutamol is known to cause minimal side effects, which may be under-recognized and progress to serious manifestations such as hypokalemia, QT prolongation, and sudden cardiac death.

Challenges and opportunities for integrating genetic testing into a diagnostic workflow: heritable long QT syndrome as a model

BACKGROUND

An increasing number of diagnostic evaluations incorporate genetic testing to facilitate accurate and timely diagnoses. The increasing number and complexity of genetic tests continue to pose challenges in deciding when to test, selecting the correct test(s), and using results to inform medical diagnoses, especially for medical professionals lacking genetic expertise. Careful consideration of a diagnostic workflow can be helpful in understanding the appropriate uses of genetic testing within a broader diagnostic workup.

CONTENT

The diagnosis of long QT syndrome (LQTS), a life-threatening cardiac arrhythmia, provides an example for this approach. Electrocardiography is the preferred means for diagnosing LQTS but can be uninformative for some patients due to the variable presentation of the condition. Family history and genetic testing can augment physiological testing to inform a diagnosis and subsequent therapy. Clinical and laboratory professionals informed by peer- reviewed literature and professional recommendations constructed a generalized LQTS diagnostic workflow. This workflow served to explore decisions regarding the use of genetic testing for diagnosing LQTS.

SUMMARY AND OUTLOOK

Understanding the complexities and approaches to integrating genetic testing into a broader diagnostic evaluation is anticipated to support appropriate test utilization, optimize diagnostic evaluation, and facilitate a multidisciplinary approach essential for achieving accurate and timely diagnoses.