Fetal Persistent junctional reciprocating tachycardia : a diagnostic and a therapeutic challenge.

A mother presented with a fetus at 22±1 weeks of gestation with a sustained supraventricular tachycardia  (SVT) at initially 186 beat per minute (bpm). The fetal M-mode echocardiography showed a 1/1 atrio ventricular ratio (with short atrioventricular (AV) interval and a long ventriculo-atrial (VA) interval, suggesting a Persistent junctional reciprocating tachycardia (PJRT) . Upon  initial present no signs of heart failure or hydrops  were noted and treament was initiated with amiodarone and  digoxin . Fetus heart rate slowed  .Postnatal electrocardiogram  Confirmed  the diagnosis of PJRT New born was put on amiodarone and proparonal). Sinus rhythm was rapidly achieved 9 days later .The patient doing well at  10 months of age with maintain of sinus rhythm. Conclusion: our case report illustrates  a particular  form of  JRT   diagnosed  prenatal PJRT  , characterized  by  a good clinical tolerance, its absence of evolution towards cardiomyopathy  and its rapid and unusual response to antiarrhythmics.

Lidocaine for chemical cardioversion of orthodromic atrioventricular reciprocating tachycardia in dogs.

BACKGROUND: Typical atrioventricular accessory pathways (APs) are composed of myocardial cells. They provide electrical connections between atria and ventricles separate from the normal conduction system. Accessory pathways can participate in a macroreentrant circuit resulting in orthodromic atrioventricular reciprocating tachycardia (OAVRT). HYPOTHESIS: Because of ultrastructural similarities of typical AP cells to ventricular myocardial cells, we hypothesized lidocaine would be effective in blocking AP conduction, thus terminating OAVRT. ANIMALS: Thirty-two consecutive client-owned dogs presenting with narrow complex tachyarrhythmias were confirmed to have OAVRT by electrophysiologic study (EPS). METHODS: Prospective, nonrandomized, single-arm study with lidocaine administered IV to dogs during OAVRT in 2 mg/kg boluses to a cumulative dose of 8 mg/kg or development of adverse effects. Electrocardiograms were monitored continuously. Subsequent EPS was performed to confirm OAVRT and the absence of other tachycardia mechanisms. RESULTS: Twenty-seven dogs experienced OAVRT cardioversion with lidocaine, before or at the time of adverse effects. Orthodromic atrioventricular reciprocating tachycardia in 5 dogs did not cardiovert before adverse effects, precluding additional dosing. Median total lidocaine dose for cardioversion was 2 mg/kg (interquartile range, 2-5.5 mg/kg). Dogs with right free wall APs had a significantly higher rate of cardioversion than did dogs with right posteroseptal APs. CONCLUSIONS AND CLINICAL IMPORTANCE: Lidocaine successfully cardioverted OAVRT in 84.4% of dogs in our study before adverse effects precluded additional dosing. In 5 dogs with dose limited by adverse effects, it is unknown whether cardioversion would have occurred at a higher cumulative dose.

Usefulness of High-Dose Oral Flecainide for Termination of Recent-Onset Atrial Fibrillation in Children.

A high dose of oral flecainide has been used for acute termination of atrial fibrillation (AF) and atrial flutter or intra-atrial re-entry tachycardia (AFL-IART) in adults. The use of flecainide for these conditions in children has not been well described. We describe our institutional experience on acute termination of AF or AFL-IART in children with a single high dose of oral flecainide in a hospital setting. All patients who received a single high dose of oral flecainide from 2009 to 2016 who were <21 years of age were included. Patients were treated only if AF or AFL-IART was less than 24 hours of duration. The dose was 300 mg for patients >70 kg, 200 mg for patients 40 to 70 kg, and 5 mg/kg for patients <40 kg. Charts were reviewed to determine demographic information, flecainide dose, termination of arrhythmia, and time to termination. There were 22 patients identified. The median age was 16 years (range 4.6 to 20.3) with a median weight of 75 kg (range 19 to 112). There were 13 patients with AF (11 with a normal heart, 85%) and 9 patients with AFL-IART (1 with a normal heart, 11%) (p <0.05). The median dose of flecainide given was 3.6 mg/kg (range 2.7 to 6.1) or 136 mg/m2 (range 90 to 171). AF in all patients (13/13, 100%) and AFL-IART in 5 of 9 patients (55%) terminated acutely (p <0.05). All patients with normal heart (12/12, 100%) and 6 of the 10 patients (60%) with heart disease have their arrhythmia terminated acutely (p <0.05). The only patients whose tachycardia did not terminate were 4 patients with IART and heart disease. The arrhythmia terminated in a median time of 60 minutes (range 30 to 120). There were no adverse events or proarrhythmia encountered. In conclusion, a single high dose of oral flecainide successfully terminated AF of less than 24 hours' duration in all pediatric patients without side effects. This approach is less effective for AFL-IART in patients with heart disease.

Recurrent hypoglycaemia in a toddler on ß-blocker therapy.

Hypoglycaemia is a well-known side effect of Propranolol. We described the case of a child presenting severe and recurrent Propranolol-induced hypoglycaemia. Those episodes were not related to prolonged fasting and were associated with only mild ketosis. Thus, therapy with ß blockers may not only aggravate classical ketotic hypoglycaemia but also interfere with glucose metabolism.

Utility of Pre-Induction Ventriculoatrial Response to Adenosine in the Diagnosis of Orthodromic Reciprocating Tachycardia.

OBJECTIVES: This study sought to evaluate the utility of ventriculoatrial (VA) conduction patterns in response to adenosine in predicting inducibility of orthodromic reciprocating tachycardia (ORT). BACKGROUND: Adenosine is known to consistently block atrioventricular (AV) nodal conduction. We hypothesized that persistent VA conduction despite administration of adenosine would have a high predictive value for identifying the presence of a retrograde accessory pathway (AP) and associated ORT. METHODS: A total of 168 patients undergoing electrophysiological study for supraventricular tachycardia (SVT) had assessment of VA conduction during ventricular pacing and adenosine administration. Standard pacing maneuvers were then used for induction and diagnosis of the SVT mechanism. RESULTS: Absence of VA block to adenosine (doses up to 24 mg) had 88% sensitivity and 91% specificity for identifying ORT (positive predictive value 76%, negative predictive value 96%). Four patients with adenosine-induced VA block and inducible ORT had decremental APs. Adenosine caused VA block in 6 patients with eccentric VA activation due to atypical AV nodal conduction, and concentric VA conduction persisted in all 12 patients with a septal AP. Adenosine unmasked free-wall APs in 10 patients by blocking AV nodal conduction, shifting VA activation from concentric to eccentric. CONCLUSIONS: The response of VA conduction to adenosine is a highly sensitive and specific method for detecting retrograde AP conduction and inducible ORT. Adenosine-induced VA block rules out inducible ORT due to a nondecremental AP. In cases of VA fusion, adenosine-induced block of AV nodal conduction can delineate the location of the AP atrial insertion site.

Fetal dilated cardiomyopathy caused by persistent junctional reciprocating tachycardia.

Ultrasound examination of a fetus at 32 weeks' gestation revealed dilated cardiomyopathy and a heart rate of 170 beats per minute. Prenatally, this mild tachycardia was not primarily suspected to be the cause of the myocardial changes. Postnatal electrocardiography revealed a persistent junctional reciprocating tachycardia (PJRT) and the diagnosis of tachycardia-induced cardiomyopathy (TICM) became apparent. After conversion to a sinus rhythm under digoxin and amiodarone, the cardiac changes regressed. PJRT is a rare form of supraventricular tachycardia. The prenatal findings in the condition have previously been described retrospectively, but it can only be diagnosed postnatally by its characteristic electrocardiographic properties. This case indicates that TICM can occur at lower heart rates than previously assumed. Even severe prenatal cardiomyopathy may be reversible once sinus rhythm has been restored.