Successful treatment of long QT syndrome-induced ventricular tachycardia with esmolol

In Vitro Drug Screening Using iPSC-Derived Cardiomyocytes of a Long QT-Syndrome Patient Carrying KCNQ1 & TRPM4 Dual Mutation: An Experimental Personalized Treatment

Congenital long QT syndrome is a type of inherited cardiovascular disorder characterized by prolonged QT interval. Patient often suffer from syncopal episodes, electrocardiographic abnormalities and life-threatening arrhythmia. Given the complexity of the root cause of the disease, a combination of clinical diagnosis and drug screening using patient-derived cardiomyocytes represents a more effective way to identify potential cures. We identified a long QT syndrome patient carrying a heterozygous KCNQ1 c.656G>A mutation and a heterozygous TRPM4 c.479C>T mutation. Implantation of implantable cardioverter defibrillator in combination with conventional medication demonstrated limited success in ameliorating long-QT-syndrome-related symptoms. Frequent defibrillator discharge also caused deterioration of patient quality of life. Aiming to identify better therapeutic agents and treatment strategy, we established a patient-specific iPSC line carrying the dual mutations and differentiated these patient-specific iPSCs into cardiomyocytes. We discovered that both verapamil and lidocaine substantially shortened the QT interval of the long QT syndrome patient-specific cardiomyocytes. Verapamil treatment was successful in reducing defibrillator discharge frequency of the KCNQ1/TRPM4 dual mutation patient. These results suggested that verapamil and lidocaine could be alternative therapeutic agents for long QT syndrome patients that do not respond well to conventional treatments. In conclusion, our approach indicated the usefulness of the in vitro disease model based on patient-specific iPSCs in identifying pharmacological mechanisms and drug screening. The long QT patient-specific iPSC line carrying KCNQ1/TRPM4 dual mutations also represents a tool for further understanding long QT syndrome pathogenesis.

Successful treatment of cardiac electrical storm in dilated cardiomyopathy using esmolol: A case report

The present study reports a case of electrical storm occurring in a 43-year-old woman with dilated cardiomyopathy. The patient suffered from a cardiac electrical storm, with 98 episodes of ventricular tachycardia rapidly degenerating to ventricular fibrillation in hospital. The patient was converted with a total of 120 defibrillations. Recurrent ventricular tachycardia/fibrillation was initiated by premature ventricular beats. The patient did not respond to the use of amiodaronum. However, the administration of esmolol stabilized the patient's heart rhythm. A moderate dose of the β-blocker esmolol, administered as an 0.5-mg intravenous bolus injection followed by an infusion at a rate of 0.15 mg/kg/min, inhibited the recurrence of ventricular fibrillation and normalized the electrocardiographic pattern. The results suggest that esmolol may be able to improve the survival rate of patients with electrical storm in dilated cardiomyopathy and should be considered as a primary therapy in the management of cardiac electrical storms.

Long QT syndrome: A therapeutic challenge

Congenital long QT syndrome (LQTS) is one of the most common cardiac channelopathies and is characterized by prolonged ventricular repolarization and life-threatening arrhythmias. The mortality is high among untreated patients. The identification of several LQTS genes has had a major impact on the management strategy for both patients and family members. An impressive genotype-phenotype correlation has been noted and genotype identification has enabled genotype specific therapies. Beta blockers continue to be the primary treatment for prevention of life threatening arrhythmias in the majority of patients. Other therapeutic options include pacemakers, implantable cardioverter defibrillators, left cardiac sympathetic denervation, sodium channel blocking medications and lifestyle modification.

Pediatric cardiac arrhythmias resulting in hemodynamic compromise

Cardiac arrhythmias in the pediatric population generally do not result in hemodynamic compromise. There are specific scenarios, however, in which an arrhythmia poses a higher risk of deterioration in a child's overall clinical condition. To minimize this risk, clinicians must be able to recognize promptly such arrhythmias, provide rapid clinical assessment, and establish appropriate interventions to avoid cardiac arrest. This article presents a brief overview of hemodynamics in children followed by a discussion of each of the arrhythmias that have a higher-than-usual potential for resulting in hemodynamic compromise. The electrocardiographic characteristics, specific clinical interventions, and nursing implications for each of these arrhythmias also are delineated.