ß-Adrenoceptor blockade can augment the torsadogenic action of risperidone.

Risperidone is a second-generation antipsychotic for treating schizophrenia and bipolar disorder. It can potently inhibit IKr, but is classified into conditional risk for torsade de pointes (TdP) by CredibleMeds®. Our previous studies using chronic atrioventricular block dogs showed that risperidone alone did not induce TdP, and that dl-sotalol (ß-adrenoceptor blockade plus IKr inhibition) induced TdP three times more frequently than d-sotalol (IKr inhibition alone). Since risperidone can block α1-adrenoceptor and decrease blood pressure, the resulting reflex-mediated increase of sympathetic tone on ß-adrenoceptor might protect the heart from its IKr inhibition-associated TdP. To validate this hypothesis, risperidone was administered to chronic atrioventricular block dogs after ß-adrenoceptor blocker atenolol infusion with monitoring J-Tpeak and Tpeak-Tend, which are proarrhythmic surrogate markers of "substrate" and "trigger" toward TdP, respectively. Atenolol alone induced TdP in 1 out of 5 dogs; moreover, an additional infusion of risperidone induced TdP in 3 out of 4 dogs. Risperidone prolonged QT interval, J-Tpeak and Tpeak-Tend in animals that induced TdP. These findings indicate that ß-adrenoceptor blockade can diminish repolarization reserve to augment risperidone's torsadogenic potential, thus advising caution when using ß-adrenoceptor blockers in patients with IKr inhibition-linked labile repolarization.

Repeated complete atrioventricular block during remifentanil administration in a pediatric patient with brain tumor and acute hydrocephalus: a case report.

BACKGROUND: Remifentanil, an ultra-short-acting µ-opioid receptor agonist, is commonly used for anesthetic management due to excellent adjustability. Remifentanil is known to cause sinus bradycardia, however, because it has a direct negative chronotropic effect on the cardiac conduction system and there is an indirect negative chronotropic effect via the parasympathetic nervous system. CASE PRESENTATION: An 8-year-old Japanese boy was diagnosed with acute hydrocephalus due to a brain tumor in the fourth ventricle and underwent emergency surgery. Imaging examination showed brainstem compression. Endoscopic third ventriculostomy and ventriculoperitoneal shunt surgery were scheduled. Remifentanil was started during induction of general anesthesia, but electrocardiogram showed sinus bradycardia, then Wenckebach-type atrioventricular block, and then complete atrioventricular block. Remifentanil was immediately discontinued, and we administered atropine sulfate. Complete atrioventricular block was restored to sinus rhythm. When remifentanil was restarted, however, the electrocardiogram again showed sinus bradycardia, Wenckebach-type atrioventricular block, and then complete atrioventricular block. Remifentanil was again immediately discontinued, we administered adrenaline, and then complete atrioventricular block was restored to sinus rhythm. Fentanyl was used instead of remifentanil with continuous infusion of dopamine. There has since been no further occurrence of complete atrioventricular block. CONCLUSIONS: This is the first known case of complete atrioventricular block in a pediatric patient with increased intracranial pressure seemingly caused by administration of remifentanil.

Not only Van Gogh: a case of BRASH syndrome with concomitant digoxin toxicity.

BACKGROUND: Bradycardia, renal failure, atrioventricular (AV) node blocking, shock, and hyperkalemia syndrome is a potentially life-threatening clinical condition characterized by bradycardia, renal failure, atrioventricular (AV) node blocking, shock, and hyperkalemia. It constitutes a vicious circle in which the accumulation of pharmacologically active compounds and hyperkalemia lead to hemodynamic instability and heart failure. CASE PRESENTATION: A 66-year-old Caucasian female patient was admitted to the emergency department presenting with fatigue and bradycardia. Upon examination, the patient was found to be anuric and hypotensive. Laboratory investigations revealed metabolic acidosis and hyperkalemia. Clinical evaluation suggested signs of digoxin toxicity, with serum digoxin concentrations persistently elevated over several days. Despite the implementation of antikalemic measures, the patient's condition remained refractory, necessitating renal dialysis and administration of digoxin immune fab. CONCLUSION: Bradycardia, renal failure, atrioventricular (AV) node blocking, shock, and hyperkalemia syndrome is a life-threatening condition that requires prompt management. It is important to also consider potential coexisting clinical manifestations indicative of intoxication from other pharmacological agents. Specifically, symptoms associated with the accumulation of drugs eliminated via the kidneys, such as digoxin. These manifestations may warrant targeted therapeutic measures.

Pembrolizumab-induced myocarditis with complete atrioventricular block and concomitant myositis in a metastatic bladder cancer patient: a case report and review of the literature.

BACKGROUND: The cardiovascular system is among the least systems affected by immune-related adverse events. We report a rare life-threatening case of pembrolizumab-induced myocarditis with complete atrioventricular block and concomitant myositis in a metastatic bladder cancer patient. CASE PRESENTATION: An 82-year-old Caucasian female with invasive urothelial carcinoma, started on first-line pembrolizumab, was admitted four days after receiving her second dose for severe asthenia, diffuse muscle aches, neck pain, and lethargy. In the emergency department, she had several episodes of bradycardia reaching 40 beats per minute associated with general discomfort and fatigue. Electrocardiography showed a third-degree atrioventricular heart block, while the patient remained normotensive. Cardiac damage parameters were altered with elevated levels of creatine phosphokinase of 8930 U/L, suggestive of immune checkpoint inhibitor-induced myositis, and troponin T of 1.060 ng/mL. Transthoracic echocardiography showed a preserved ejection fraction. Pembrolizumab-induced myocarditis was suspected. Therefore, treatment was initiated with high-dose glucocorticoids for 5 days, followed by a long oral steroid taper. A pacemaker was also implanted. Treatment resulted in the resolution of heart block and a decrease in creatine phosphokinase to the normal range. CONCLUSION: Life-threatening cardiac adverse events in the form of myocarditis may occur with pembrolizumab use, warranting vigilant cardiac monitoring. Troponin monitoring in high-risk patients, along with baseline echocardiography may help identify this complication promptly to prevent life-threatening consequences.

Transient second-degree type 2 atrioventricular block after infliximab infusion in a patient with Crohn's disease and heterozygous familial hypercholesterolemia.

Current treatments for patients in the active phase of Crohn's disease (CD) include conventional treatments and biological treatments. Infliximab (IFX), a TNF-α antagonist, is recommended to induce remission in patients with moderate-to-severe CD who have not responded to conventional therapy. IFX terminates the inflammatory cascade by inhibiting the nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and caspase signaling pathways and increases the apoptosis of activated T cells in inflamed tissues.

Transient Complete Atrioventricular Block Associated With Herbal Supplement Use.

INTRODUCTION: Increasing and easy availability of so-called natural/herbal supplements pose the unique challenge of identifying associated side effects, including arrhythmias in otherwise-healthy individuals. CASE PRESENTATION: A 25-year-old female patient presented to the emergency department with fatigue and lightheadedness. The electrocardiogram showed complete AV block with a junctional escape rhythm at 55 beats per minute with QT prolongation (542ms). One week ago, she started to use a herbal medication (Muscle Eze Advanced) for muscle cramps after workouts. Extensive cardiac testing, including complete blood count, complete metabolic panel, TSH, transthoracic echocardiography, urine drug analysis, Lyme antibody were negative. Normal sinus rhythm was restored spontaneously within 1 day of discontinuing the herbal medication. PR and corrected QT intervals returned to baseline over the next two weeks. CONCLUSION: Muscle Eze Advanced consists of seven ingredients, including Melissa officinalis and Valeriana officinalis that have negative chronotropic, negative dromotrophic and QT prolonging effects. Recognizing the association between certain over-the-counter supplements and brady-arrhythmias may circumvent need for permanent pacemakers - an important consideration especially in the young.

The Antiarrhythmic Action of the Na+/Ca2+ Exchanger Inhibitor SEA0400 on Drug-Induced Long QT Syndrome Depends on the Severity of Proarrhythmic Conditions in Anesthetized Atrioventricular Block Rabbits.

To clarify the pharmacological properties of the Na+/Ca2+ exchanger (NCX) inhibitor SEA0400 as an antiarrhythmic agent, we assessed its effects on rapid component of delayed rectifier K+ current (IKr) blocker-induced torsade de pointes (TdP) in isoflurane-anesthetized rabbits. Atrioventricular block was induced in rabbits using a catheter ablation technique, and the monophasic action potential (MAP) of the right ventricle was measured under electrical pacing at 60 beats/min. In non-treated control animals, intravenous administration of low-dose (0.3 mg/kg) or high-dose nifekalant (3 mg/kg) prolonged the MAP duration (MAP90) by 113 ± 11 ms (n = 5) and 237 ± 39 ms (n = 5), respectively, where TdP was induced in 1/5 animals treated with a low dose and in 3/5 animals treated with a high dose of nifekalant. In SEA0400-treated animals, low- and high-dose nifekalant prolonged the MAP90 by 65 ± 13 ms (n = 5) and 230 ± 20 ms (n = 5), respectively. No TdP was induced by the low dose but 1/5 animals treated with a high dose of nifekalant developed TdP. In verapamil-treated animals, low-dose and high-dose nifekalant prolonged MAP90 by 50 ± 12 ms (n = 5) and 147 ± 30 ms (n = 5), respectively, without inducing TdP. These results suggest that SEA0400 has the potential to inhibit low-dose nifekalant-induced TdP by suppressing the MAP-prolonging action of nifekalant, whereas the drug inhibited high-dose nifekalant-induced TdP without affecting the MAP-prolonging action of nifekalant. This may reveal that, in contrast to verapamil, the antiarrhythmic effects of SEA0400 on IKr blocker-induced TdP may be multifaceted, depending on the severity of the proarrhythmogenic conditions present.

Failure of diltiazem to prevent 1:1 conduction of atrial flutter: a case report.

BACKGROUND: Atrial flutter with 1:1 conduction to the ventricles is a dangerous cardiac arrhythmia. Contemporary guidelines recommend atrioventricular nodal blocking agents should be co-administered with class 1C anti-arrhythmics, as prophylaxis against 1:1 flutter. No guidance is provided on the type or strength of atrioventricular nodal blockade required, and in practice, these agents are frequently prescribed at low dose, or even omitted, due to their side effect profile. CASE PRESENTATION: A 62 year old Caucasian man with a history of paroxysmal atrial fibrillation treated with flecainide, presented with atrial flutter with 1:1 conduction to the ventricles and was cardioverted. Diltiazem was added to prevent this complication and he again presented with atrial flutter with 1:1 conduction to the ventricles, despite prophylaxis with coadministration of diltiazem. CONCLUSIONS: This case report demonstrates failure of diltiazem to prevent 1:1 flutter in a patient chronically treated with flecainide for paroxysmal atrial fibrillation.

Electropharmacological Characterization of Licorice Using the Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes Sheets and the Chronic Atrioventricular Block Dogs.

Licorice has been traditionally prescribed for palpitation, whereas its overdose has caused lethal arrhythmias including torsade de pointes. Licorice contains glycyrrhizic acid of ≥ 2% (w/w), which is hydrolyzed to glycyrrhetinic acid (GRA) in the intestine. Since their cardiac electropharmacological properties are not fully understood, we assessed them to ask mechanism of licorice-induced torsade de pointes. GRA at 0.1, 1 and 10 µg/mL was cumulatively applied to the human induced pluripotent stem cell-derived cardiomyocytes sheets (n = 6). GRA shortened spontaneous activation interval and repolarization period, and decreased maximum contraction velocity, indicating Ca2+ channel blockade. It prolonged effective refractory period and post-repolarization refractoriness with a steep frequency-dependency, whereas it delayed conduction with a modest use-dependency, resembling lidocaine in the mode of Na+ channel-blocking action. Meanwhile, Kanzoto containing a decoction of licorice alone in a dose of 2 or 6 g/body/day was orally administered to the conscious chronic atrioventricular block dogs for 3 days (n = 4). Kanzoto prolonged QT interval with increasing its temporal dispersion, suggesting K+ channel suppression, and slightly decreased the plasma K+ concentration without inducing torsade de pointes. Moreover, it significantly suppressed atrial and idioventricular rates, leading to sinus arrest along with the onset of ventricular fibrillation in one animal, possibly due to Na+ channel blockade. These results indicate that electropharmacological profile of licorice can be explained by Na+, Ca2+ and K+ channels blockade, which may be associated with low torsadogenic risk, but might contribute to the onset of other types of lethal ventricular arrhythmias.

A Case Report of Acute Onset and Rapid Resolution of Atrioventricular Block After Sugammadex: Is the Autonomic System Involved?

Administering sugammadex to reverse neuromuscular blockade can cause marked bradycardia and rarely asystole. In this case, a rapid onset, biphasic heart rate response; slowing then speeding, after administering sugammadex was noted while at steady state, 1.3% end-tidal sevoflurane. On review of the electrocardiogram (ECG), the heart rate slowing coincided with the onset of a second-degree, Mobitz type I block that lasted 45 seconds. No other events, drugs, or stimuli coincided with the event. The acute onset and transient nature of the atrioventricular block without evidence of ischemia implies a brief parasympathetic effect on the atrioventricular node after sugammadex administration.

Fingolimod-related atrioventricular block in paediatric age group with multiple sclerosis: two case reports.

Multiple sclerosis is a chronic inflammatory and demyelinating disease of the central nervous system, usually seen in young adults. Early onset of multiple sclerosis at age younger than 18 years is called paediatric multiple sclerosis. Unlike adult multiple sclerosis, paediatric multiple sclerosis causes morbidity at earlier ages and often progresses in a relapsing-remitting form. Although fingolimod is an effective drug used as a disease-modifiying therapy agent in relapsing-remitting paediatric multiple sclerosis patients, it can cause dysryhthmia in the early period after first dose. Our first case is a 14-year-old girl with relapsing-remitting paediatric multiple sclerosis patients who was started to take fingolimod treatment. In the fifth hour of the follow-up, asymptomatic bradycardia was seen and the electrocardiogram was consistent with first-degree atrioventricular block. Her rhythm got spontaneously normal after 12 hours. Second case was 13 years old girl. Steroid treatment was started after her first paediatric multiple sclerosis attack. Despite treatment, she had a second attack 2 weeks after the first attack. Therefore, the neurologist switched to fingolimod therapy. Second-degree atrioventriculer block developed after 4 hours from the initiation of therapy. After 8 hours, rhythm regressed to first-degree atrioventricular block then returned to normal up to 13th hours of follow up. The aim of this article is to draw attention to dysrhythmia side effect of fingolimod which can be fatal. Therefore, the clinician must take precautions. Close cardiac rhythm monitoring is mandatory after the initiation fingolimod theraphy.

Adenosine as adjunctive therapy in acute coronary syndrome: a meta-analysis of randomized controlled trials.

AIMS: Adenosine has been tested in several randomized controlled trials (RCTs) to minimize the incidence of coronary microvascular obstruction (CMVO). The aim of this study was to pool all the RCTs comparing intracoronary or intravenous adenosine versus placebo in patients with acute coronary syndrome (ACS) undergoing myocardial revascularization. METHODS AND RESULTS: PubMed and Scopus electronic databases were scanned for eligible studies up to 5th June 2022. A total of 26 RCTs with 5843 patients were included. Efficacy endpoints were major adverse cardiac events (MACE), all-cause death, non-fatal myocardial infarction, and heart failure. Atrioventricular blocks and ventricular fibrillation/sustained ventricular tachycardia (VF/SVT) were the safety endpoints. Myocardial blush grade, thrombolysis in myocardial infarction (TIMI) flow grade, left ventricular ejection fraction (LVEF), infarct size, and ST-segment resolution were also assessed. Adenosine administration was not associated with any clinical benefit in terms of MACE, all-cause death, non-fatal myocardial infarction, and heart failure. However, adenosine was associated with an increased rate of advanced atrioventricular blocks and of VF/SVT in studies with total mean ischaemic time >3 h, compared to placebo. Remarkably, among patients undergoing percutaneous coronary intervention, adenosine was associated with reduced myocardial blush grade 0-1 and TIMI flow grade 0-2, compared to placebo. Furthermore, adenosine did not show favourable effects on LVEF and infarct size. CONCLUSION: Adenosine infusion, as adjunctive therapy in ACS, was associated with an increased risk of advanced atrioventricular blocks and increased rates of adenosine-triggered ventricular arrhythmias in patients with long ischaemic time, without providing any clinical benefit compared to placebo.

Adenosine triphosphate (ATP): a safe and effective vasodilator for stress perfusion cardiac magnetic resonance imaging.

AIM: To evaluate the efficiency and safety of adenosine triphosphate (ATP) as a stress agent in a cohort of patients undergoing stress perfusion cardiac magnetic resonance imaging (CMRI). MATERIALS AND METHODS: This retrospective study was conducted between December 2019 and October 2021. The study recruited patients who underwent stress perfusion CMRI using ATP as a vasodilator. Adverse events, such as chest pain, flushing, dyspnoea, headache, and splenic switch-off (SSO) phenomenon, were evaluated in the patients who underwent stress perfusion CMRI. RESULTS: The study included 107 patients (age range: 53 ± 11 years; male:female, 62%:38%). The haemodynamic response (heart rate increased by ≥ 10 beats/min) was quick and observed within 2 minutes of ATP infusion. Scanning was stopped in three patients because of atrioventricular block. CMRI images of seven out of 104 patients were excluded from the final analysis because of inferior quality. During ATP infusion, 37/107 patients (35%) experienced mild adverse events, such as chest pain, flushing, dyspnoea, headache, and atrioventricular block. Myocardial infarction and bronchospasms were not observed during ATP infusion. SSO, a marker of adequate stress, was observed in 91% (94/103) of the patients who underwent stress perfusion CMRI. CONCLUSIONS: As a coronary vasodilator, ATP was safe for stress perfusion CMRI. In addition, the adverse events during ATP infusion were mild, which were relieved within 2 minutes of ATP injection cessation. SSO could serve as an indicator of stress success in ATP stress perfusion CMRI.

Third-degree atrioventricular block caused by intoxication with rhododendron leaves.

We report the case of a 41-year-old human with third-degree atrioventricular block caused due to intoxication with water concoction prepared from Rhododendron leaves. Such poisoning is rare. It is prone to arrhythmia with hemodynamic instability and is confused with various diseases. For these reasons, the correct diagnosis and treatment of this poisoning are particularly important. We confirmed it by analyzing the remaining liquid carried by the family members. After symptomatic and supportive treatment, the patient was discharged uneventfully.

Role of cardiac α1-adrenoreceptors for the torsadogenic action of IKr blocker nifekalant in the anesthetized atrioventricular block rabbit.

We analyzed role of cardiac α1-adrenoreceptors for the torsadogenic action of IKr blocker nifekalant in isoflurane-anesthetized atrioventricular block rabbits. Bradycardia was induced by atrioventricular node ablation, and the ventricle was electrically driven at a constant rate of 60 beats/min throughout the experiments to prevent rate-dependent modification by the IKr blocker in ventricular repolarization phase. Nifekalant (3 mg/kg per 10 min, n = 5) prolonged the duration of monophasic action potential (MAP90) by +178 ± 43 ms, increased the short-term variability of repolarization (STV) to 4.2 ± 1.2 ms, and induced torsade de pointes (TdP) in 1 animal. In the presence of methoxamine (n = 5), nifekalant prolonged the MAP90 by +328 ± 32 ms, increased the STV to 8.0 ± 1.0 ms, and induced TdP in 2 animals. In the presence of prazosin and methoxamine (n = 5), nifekalant prolonged the MAP90 by +267 ± 22 ms, increased the STV to 9.2 ± 3.6 ms, and induced no TdP. These results suggest that cardiac α1-adrenoreceptor activation by methoxamine essentially sensitizes the rabbit heart to nifekalant-induced QT interval prolongation, leading to the onset of TdP.

Validation of Risk-Stratification Method for the Chronic Atrioventricular Block Cynomolgus Monkey Model and Its Mechanistic Interpretation Using 6 Drugs With Pharmacologically Distinct Profile.

Validation of risk-stratification method for the chronic atrioventricular block cynomolgus monkey model and its mechanistic interpretation was performed using 6 pharmacologically distinct drugs. The following drugs were orally administered in conscious state, astemizole: 1, 5, and 10 mg/kg (n = 6); haloperidol: 1, 10, and 30 mg/kg (n = 5); amiodarone: 30 mg/kg (n = 4); famotidine: 10 mg/kg (n = 4); levofloxacin: 100 mg/kg (n = 4); and tolterodine: 0.2, 1, and 4.5 mg/kg (n = 4). Astemizole of 5 and 10 mg/kg significantly prolonged ΔΔQTcF, whereas no significant change was observed by the others. Torsade de pointes (TdP) was induced by astemizole of 5 and 10 mg/kg in 3/6 and 6/6, and by haloperidol of 10 and 30 mg/kg in 1/5 and 1/5, respectively, which was not observed in the others. Torsadogenic risk of the drugs was quantified using the criteria for the monkey model specified in our previous study. Namely, high-risk drugs induced TdP at ≤ 3 times of their maximum clinical daily dose. Intermediate-risk drugs did not induce TdP at this dose range, but induced it at higher doses. Low/no-risk drugs never induced TdP at any dose tested. The magnitude of risk was intermediate for astemizole and haloperidol, and low/no risk for the others. The prespecified, risk-stratification method for the monkey model may solve the issue existing between nonclinical models and patients with labile repolarization, which can reinforce the regulatory decision-making and labeling at time of marketing application of nondouble-negative drug candidate (hERG assay positive and/or in vivo QT study positive).

A critical review of ozanimod for the treatment of adults with moderately to severely active ulcerative colitis.

INTRODUCTION: Ozanimod is a sphingosine-1-phosphate (S1P) modulator that inhibits lymphocyte trafficking from lymph nodes to the circulation. It is approved by the US Food and Drug Administration (FDA) for the treatment of relapsing multiple sclerosis and most recently for the management of moderate-severe ulcerative colitis (UC). AREAS COVERED: Here we review the status of drugs approved for moderate-severe UC, the unmet needs in the management of UC, proposed mechanisms of action of S1P modulators, clinical data regarding ozanimod in UC, and emerging S1P modulators being evaluated in inflammatory bowel disease. EXPERT OPINION: Ozanimod is superior to placebo in inducing and maintaining clinical and endoscopic remission in UC. Adverse events include transient asymptomatic bradycardia, first-degree atrioventricular blocks, transient asymptomatic hepatotoxicity, macular edema in patients with preexisting risk factors, and increased risk of nasopharyngitis. Ozanimod is contraindicated in patients with clinically significant cardiovascular diseases, type II second-, or third-degree atrioventricular blocks, and females of childbearing age who do not use contraception. Ozanimod is the first S1P modulator to be approved for UC, offering a new therapeutic class option for patients. It has the advantages of being convenient with a once-daily oral administration, non-immunogenic, and overall safe when used in patients without contraindications.

Complete atrioventricular block with diastolic mitral regurgitation due to severe lithium intoxication. A case report.

BACKGROUND: Lithium remains the first line therapy for treatment of bipolar disorder and is widely used in psychiatry despite its narrow therapeutic window. Cardiac side effects are uncommon, but when they are present, they can vary from benign repolarization changes to life threatening tachyarrhythmias as well as conduction time abnormalities. In extremely rare cases complete atrioventricular block with cardiogenic shock can be seen. METHODS: We report the clinical course and outcome of a 79-year-old patient who presented with bradyarrhythmias and a complete atrioventricular block due to severe lithium intoxication. The patient was admitted to ICU where fluid resuscitation and intermittent haemodialysis were performed. Interestingly, the cardiac ultrasound on ICU showed a diastolic mitral regurgitation which was related to the underlying complete atrioventricular block. RESULTS: After two cycles of haemodialysis lithium blood levels were normalised and 24 h later sinus rhythm was restored without any signs of atrioventricular block. The patient recovered completely. CONCLUSION: Lithium is widely used for the treatment of bipolar disorder and it can rarely lead to complete atrioventricular block. If the physician encounters a patient with a history of lithium use, who also shows cardiac arrhythmias, then lithium intoxication should always be ruled out. Haemodialysis is the treatment of choice in severe lithium intoxication. Diastolic mitral regurgitation can hint towards underlying atrioventricular conduction disturbances.