Lidocaine for chemical cardioversion of orthodromic atrioventricular reciprocating tachycardia in dogs

Clinical, electrocardiographic, and diagnostic imaging features and outcomes in cats with electrocardiographic diagnosis of ventricular pre-excitation: a retrospective study of 23 cases (2010-2022)

INTRODUCTION/OBJECTIVES

Ventricular pre-excitation (VPE) occurs when atrial electrical impulses prematurely excite the ventricles through an aberrant muscle bundle known as an accessory pathway (AP). Orthodromic atrioventricular reciprocating tachycardia is a re-entrant, narrow complex supraventricular tachycardia (SVT), maintained through retrograde conduction over an AP. The study aimed to describe patient signalments, clinical signs, electrocardiographic (ECG) and diagnostic imaging features, treatments, prognostic variables, and outcomes in cats with ECG diagnosis of VPE.

ANIMALS

Twenty-three cats diagnosed with VPE between January 2010 and August 2022 were included in this study.

MATERIALS AND METHODS

This was a multicenter, retrospective study with 23 cats diagnosed with VPE between January 2010 and August 2022. Ventricular pre-excitation diagnosis was based on ECG evidence of shortened PR interval, delta wave, and prolonged QRS duration. The median survival time (MST) was estimated by the Kaplan-Meier curve. Log-rank tests were performed to assess for an association between clinical signs or presence of structural heart disease on the MST.

RESULTS

Fourteen (60.8%) cats with VPE also had SVT documented on ECG, with seven of 14 with ECG confirmation of orthodromic atrioventricular reciprocating tachycardia. Four (17.4%) cats had suspected AP-mediated tachyarrhythmia based on associated clinical signs. Common presenting signs included collapse (15/23; 65.2%) and respiratory distress (14/23; 60.8%). Five (21.7%) cats were asymptomatic. Heart rate during SVT ranged from 310 to 420 bpm (median: 375 bpm). Initial treatment included atenolol (10/18), sotalol (5/18), diltiazem (2/18), and amiodarone (1/18). From the date of diagnosis, MST was 1872 days (5.1 years).

CONCLUSIONS

The majority of cats with VPE also had symptomatic SVT. The prognosis for cats with VPE is considered good with an MST of greater than five years.

Spontaneous pre-excited supraventricular tachycardias in a Labrador Retriever

A four-year-old Labrador Retriever was presented for intermittent tachycardia. The electrocardiogram showed sinus rhythm conducted with ventricular pre-excitation and short runs of orthodromic atrioventricular reciprocating tachycardia. Four months later, the rhythm degenerated into a symptomatic sustained tachycardia, suspected to be pre-excited atrial fibrillation, a potentially life-threatening rhythm in the presence of an accessory pathway with a short refractory period. Two days after initiating oral diltiazem, the dog deteriorated and represented with sustained orthodromic atrioventricular reciprocating tachycardia, which was terminated by a precordial chest thump. It proceeded to sinus rhythm with ventricular pre-excitation followed by an episode of pre-excited focal atrial tachycardia. A bolus of lidocaine IV successfully restored sinus rhythm and sotalol treatment was started. The dog clinically recovered but died spontaneously 24 h later. This is the first case report that describes spontaneous pre-excited focal atrial tachycardia.

USP14: Structure, Function, and Target Inhibition

Ubiquitin-specific protease 14 (USP14), a deubiquitinating enzyme (DUB), is associated with proteasomes and exerts a dual function in regulating protein degradation. USP14 protects protein substrates from degradation by removing ubiquitin chains from proteasome-bound substrates, whereas promotes protein degradation by activating the proteasome. Increasing evidence have shown that USP14 is involved in several canonical signaling pathways, correlating with cancer, neurodegenerative diseases, autophagy, immune responses, and viral infections. The activity of USP14 is tightly regulated to ensure its function in various cellular processes. Structural studies have demonstrated that free USP14 exists in an autoinhibited state with two surface loops, BL1 and BL2, partially hovering above and blocking the active site cleft binding to the C-terminus of ubiquitin. Hence, both proteasome-bound and phosphorylated forms of USP14 require the induction of conformational changes in the BL2 loop to activate its deubiquitinating function. Due to its intriguing roles in the stabilization of disease-causing proteins and oncology targets, USP14 has garnered widespread interest as a therapeutic target. In recent years, significant progress has been made on identifying inhibitors targeting USP14, despite the complexity and challenges in improving their selectivity and affinity for USP14. In particular, the crystal structures of USP14 complexed with IU1-series inhibitors revealed the underlying allosteric regulatory mechanism and enabled the further design of potent inhibitors. In this review, we summarize the current knowledge regarding the structure, regulation, pathophysiological function, and selective inhibition of USP14, including disease associations and inhibitor development.

Rhythm disturbances associated with lidocaine administration in four dogs with supraventricular tachyarrhythmias

OBJECTIVE

To describe arrhythmias associated with administration of lidocaine in dogs treated for supraventricular tachyarrhythmias.

CASE SUMMARIES

Four dogs with recent-onset supraventricular tachyarrhythmias: 3 dogs had atrial fibrillation (AF), and 1 had focal atrial tachycardia (FAT), which was thought to be AF at the time of assessment. The substrate of the supraventricular tachyarrhythmia was considered to be due to primary cardiomyopathy in 1 dog, high vagal tone in 2 dogs, and the change in hemodynamics from heavy sedation in 1 dog. Pharmacological cardioversion using lidocaine was only successful in the 2 dogs with vagally mediated AF. In these 2 cases, lidocaine administration resulted in a paroxysmal atrial flutter that was self-limiting and quickly led to sinus rhythm within 10 seconds in 1 dog but did not change over a 5-minute interval and required additional boluses in another dog. In the latter case, the dog showed severe bradycardia for 17.5 seconds prior to achieving sinus rhythm. The 2 unsuccessful cases both developed ventricular arrhythmias shortly after the lidocaine administration, with 1 case degenerating into ventricular fibrillation and cardiac arrest.

NEW OR UNIQUE INFORMATION PROVIDED

Arrhythmias associated with lidocaine should be considered when treating dogs with supraventricular tachyarrhythmia.

Lidocaine inhibits the proliferation and invasion of hepatocellular carcinoma by downregulating USP14 induced PI3K/Akt pathway

Previous studies have found that Lidocaine (Lido) has marked anti-tumor effects. The purpose of this study was to explore the effect and mechanism of Lido on hepatocellular carcinoma (HCC). Here, the Huh-7 and SMMC-7721 HCC cells were treated with Lido, then the proliferation, migration and invasion of HCC cells were detected by CCK8, wounding healing assay and Transwell assay. Besides, apoptotic proteins (including Caspase3 and Bcl2), epithelial-mesenchymal transition (EMT) associated markers (including E-cadherin and Vimentin), USP14, PI3K/Akt pathway were detected by western blot. Our results revealed that Lido significantly inhibited the proliferation, migration and invasion while aggravate the apoptosis of HCC cells, as well as the expression of USP14 and the activation of PI3K/Akt. Loss-of-function experiments confirmed that USP14 downregulation attenuated the malignant behaviors of HCC cells through repressing PI3K/Akt signaling pathway. Mechanistically, USP14 functioned by deubiquitinating and activating PI3K. In conclusion, Lido inhibits the proliferation and metastasis of HCC cells by targeting USP14 and its downstream PI3K/Akt signaling pathway.

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.