Electrocardiographic changes associated with beta-blocker toxicity

Electrocardiogram Features in Non-Cardiac Diseases: From Mechanisms to Practical Aspects

Despite the noteworthy advancements and the introduction of new technologies in diagnostic tools for cardiovascular disorders, the electrocardiogram (ECG) remains a reliable, easily accessible, and affordable tool to use. In addition to its crucial role in cardiac emergencies, ECG can be considered a very useful ancillary tool for the diagnosis of many non-cardiac diseases as well. In this narrative review, we aimed to explore the potential contributions of ECG for the diagnosis of non-cardiac diseases such as stroke, migraine, pancreatitis, Kounis syndrome, hypothermia, esophageal disorders, pulmonary embolism, pulmonary diseases, electrolyte disturbances, anemia, coronavirus disease 2019, different intoxications and pregnancy.

Kardiyovasküler ilaç zehirlenmelerinin ileriye dönük analizi

Purpose: The aim of this study is to provide data about diagnosis, treatment, and results of the patients poisoned by drugs affecting the cardiovascular system. Materials and Methods: Patients aged 18 and over who applied to the emergency department with drug poisoning affecting cardiovasculer system were included in the study. The demographic data, drugs and doses, emergency treatment and the time of development of shock or bradycardia, treatment, antidotes and invasive procedures were recorded. Results: In our study twenty-five patients, 8 (32 %) male and 17 (68 %) female, were included. At the admission, 56 % (n=14) had hypotension, 8 % (n=2) had bradycardia, at the second hour 76 % (n=19) had hypotension, 16 % (n=4) had bradycardia. Within 6 hours after admission, 80 % (n=20) patients had hypotension, 28 % (n=7) patients had bradycardia at least once. Fifty-two percent (n=13) of the patients calcium, 36 % (n=9) glukagon, 32 % (n=8) lipid, 12 % (n=3) atropine, 20 % (n=5) positive inotropes were given. Conclusion: Lipid therapy produces positive results in patients who did not improve with calcium, glucagon and fluid therapy. Patients who received calcium channel blockers experienced more cardiogenic shock and bradycardia was more common in patients receiving beta-blockers.

Extracorporeal treatment for poisoning to beta-adrenergic antagonists: systematic review and recommendations from the EXTRIP workgroup

BACKGROUND

β-adrenergic antagonists (BAAs) are used to treat cardiovascular disease such as ischemic heart disease, congestive heart failure, dysrhythmias, and hypertension. Poisoning from BAAs can lead to severe morbidity and mortality. We aimed to determine the utility of extracorporeal treatments (ECTRs) in BAAs poisoning.

METHODS

We conducted systematic reviews of the literature, screened studies, extracted data, and summarized findings following published EXTRIP methods.

RESULTS

A total of 76 studies (4 in vitro and 2 animal experiments, 1 pharmacokinetic simulation study, 37 pharmacokinetic studies on patients with end-stage kidney disease, and 32 case reports or case series) met inclusion criteria. Toxicokinetic or pharmacokinetic data were available on 334 patients (including 73 for atenolol, 54 for propranolol, and 17 for sotalol). For intermittent hemodialysis, atenolol, nadolol, practolol, and sotalol were assessed as dialyzable; acebutolol, bisoprolol, and metipranolol were assessed as moderately dialyzable; metoprolol and talinolol were considered slightly dialyzable; and betaxolol, carvedilol, labetalol, mepindolol, propranolol, and timolol were considered not dialyzable. Data were available for clinical analysis on 37 BAA poisoned patients (including 9 patients for atenolol, 9 for propranolol, and 9 for sotalol), and no reliable comparison between the ECTR cohort and historical controls treated with standard care alone could be performed. The EXTRIP workgroup recommends against using ECTR for patients severely poisoned with propranolol (strong recommendation, very low quality evidence). The workgroup offered no recommendation for ECTR in patients severely poisoned with atenolol or sotalol because of apparent balance of risks and benefits, except for impaired kidney function in which ECTR is suggested (weak recommendation, very low quality of evidence). Indications for ECTR in patients with impaired kidney function include refractory bradycardia and hypotension for atenolol or sotalol poisoning, and recurrent torsade de pointes for sotalol. Although other BAAs were considered dialyzable, clinical data were too limited to develop recommendations.

CONCLUSIONS

BAAs have different properties affecting their removal by ECTR. The EXTRIP workgroup assessed propranolol as non-dialyzable. Atenolol and sotalol were assessed as dialyzable in patients with kidney impairment, and the workgroup suggests ECTR in patients severely poisoned with these drugs when aforementioned indications are present.

Kanglexin, a novel anthraquinone compound, protects against myocardial ischemic injury in mice by suppressing NLRP3 and pyroptosis

Pyroptosis is a form of inflammatory cell death that could be driven by the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation following myocardial infarction (MI). Emerging evidence suggests the therapeutic potential for ameliorating MI-induced myocardial damages by targeting NLRP3 and pyroptosis. In this study, we investigated the myocardial protection effect of a novel anthraquinone compound (4,5-dihydroxy-7-methyl-9,10-anthraquinone-2-ethyl succinate) named Kanglexin (KLX) in vivo and in vitro. Male C57BL/6 mice were pre-treated either with KLX (20, 40 mg· kg^-1per day, intragastric gavage) or vehicle for 7 consecutive days prior to ligation of coronary artery to induce permanent MI. KLX administration dose-dependently reduced myocardial infarct size and lactate dehydrogenase release and improved cardiac function as compared to vehicle-treated mice 24 h after MI. We found that MI triggered NLRP3 inflammasome activation leading to conversion of interleukin-1β (IL-1β) and IL-18 into their active mature forms in the heart, which could expand the infarct size and drive cardiac dysfunction. We also showed that MI induced pyroptosis, as evidenced by increased DNA fragmentation, mitochondrial swelling, and cell membrane rupture, as well as increased levels of pyroptosis-related proteins, including gasdermin D, N-terminal GSDMD, and cleaved caspase-1. All these detrimental alterations were prevented by KLX. In hypoxia- or lipopolysaccharide (LPS)-treated neonatal mouse ventricular cardiomyocytes, we showed that KLX (10 μM) decreased the elevated levels of terminal deoxynucleotidyl transferase dUTP nick end labeling- and propidium iodide-positive cells, and pyroptosis-related proteins. We conclude that KLX prevents MI-induced cardiac damages and cardiac dysfunction at least partly through attenuating NLRP3 and subsequent cardiomyocyte pyroptosis, and it is worthy of more rigorous investigations for its potential for alleviating ischemic heart disease.

A case of fatal acebutolol poisoning: an illustration of the potential of molecular networking

Acebutolol is a β1-selective adrenergic receptor antagonist with moderate membrane-stabilizing activity and intrinsic sympathomimetic activity; accordingly, the drug is indicated in hypertension, angina pectoris, and arrhythmia. However, acebutolol's beta-blocking properties also extend the QRS and QTc intervals, and may predispose the patient to ventricular tachydysrhythmia. Here, we report autopsy and toxicological findings on a fatal case of acebutolol self-poisoning in a 70-year-old woman. Toxicological analyses of post-mortem samples (using a liquid chromatography high-resolution mass spectrometry (LC-HR-MS) method) highlighted high concentrations of acebutolol and its metabolite diacetolol in femoral blood (92.8 mg/L and 21.2 mg/L, respectively) and other matrices (cardiac blood, urine, bile, and gastric contents). A molecular networking approach provided useful information on acebutolol's metabolism and revealed the existence of an unknown phase II metabolite of acebutolol. Molecular networking also facilitated visualization of the complex LC-HR-MS/MS datasets and the sample-to-sample comparisons that confirmed massive acebutolol intoxication by ingestion.

Effects of Cardiac Resynchronization Therapy on Ventricular Electrical Remodeling in Patients With Heart Failure

Cardiac resynchronization therapy (CRT) reverses structural remodeling of the left ventricle. We investigated whether CRT reverses left-ventricular electrical remodeling.Eighty patients were enrolled and implanted with CRT-devices. Echocardiography and electrocardiography data were obtained from each patient prior to implantation and two years after implantation. At two years after implantation, the patients were classified into a responder group and a non-responder group based on echocardiography.Over the next 2 years, 75 patients completed follow-up, and 5 patients had died. Echocardiography results showed that 23 patients could be classified as non-responders and 52 as responders. Larger numbers of non-responders were diagnosed with either ischemic cardiomyopathy (ICM) or nonspecific intraventricular conduction delay (NICD). The intrinsic QRS duration was not changed in responders, patients with dilated cardiomyopathy, or in the patient categories of male and female. However, the intrinsic QRS duration was significantly prolonged in non-responders and patients with ischemic cardiomyopathy (P = 0.041). The mean left ventricular end-diastolic diameter in the responder group was significantly decreased by CRT (P < 0.05), while there was no significant change in intrinsic QRS duration.While CRT does not reduce the intrinsic QRS duration, it can delay negative ventricular electrical remodeling. Continuous CRT is necessary.

The effect of fat emulsion on hemodynamics following treatment with propranolol and clonidine in anesthetized rats

OBJECTIVES

There is evidence indicating that intravenous fatty emulsion (IFE) is beneficial in restoring circulatory function in certain types of drug overdose. The authors investigated the hemodynamic effects of IFE compared to epinephrine in rats treated with propranolol and clonidine.

METHODS

Anesthetized male Sprague-Dawley rats were instrumented for measurement of hemodynamics. Rats were randomly assigned to one of six groups (n = 6-8), and each received a clonidine infusion (150 μg/kg) or an equivalent volume of normal saline (0.9% NaCl) over 1 hour. Each rat then received normal saline (1.0 mL/kg) or propranolol (15 to 20 mg/kg). Thereafter, each rat received a dose of IFE (20% solution; 1.0 mL/kg) or epinephrine (2.0 μg/kg) or an equivalent volume of normal saline (1.0 mL/kg).

RESULTS

Propranolol alone or with clonidine significantly (p < 0.05) reduced a number of hemodynamic parameters (mean arterial pressure, 37% to 70%; heart rate, 30% to 51%; cardiac contractility [dP/dtmax], 50% to 67%; and abdominal aortic blood flow, 50% to 83%), while increasing PR intervals (65% to 85%) and QTc intervals (26% to 64%). Saline and epinephrine treatment after propranolol and clonidine combined resulted in no survivors in saline and two out of six in epinephrine group. IFE resulted in significant survival (seven out of eight) for 30 minutes in rats treated with propranolol alone, and propranolol combined with clonidine (seven out of eight).

CONCLUSIONS

These data demonstrate that IFE is effective for resuscitating rats overdosed on propranolol combined with clonidine. The effect of IFF is unlikely due to a direct positive inotropic or chronotropic action on the myocardium. IFE is also more effective than epinephrine treatment in this paradigm.

Reevaluation of arrhythmias and alterations of the autonomic nervous activity induced by T-2 toxin through telemetric measurements in unrestrained rats

This study was conducted to clarify and reevaluate the cardiac and autonomic nervous effects of T-2 toxin, which had been previously examined by several acute experiments, in unrestrained and conscious rats implanted with telemetric transmitters. Two groups of rats were given two subcutaneous injections of 0.1 and 0.5 mg/kg of T-2 toxin with an interval of 3 days. Two other groups of rat were pre-implanted with osmotic minipumps by which atropine (20 mg/kg/day) or propranolol (100 mg/kg/day) was continuously administered preceding subcutaneous injection of T-2 toxin (0.5 mg/kg). The present study demonstrated that T-2 toxin caused marked arrhythmias, such as second-degree atrioventricular (AV) block, sinus bradycardia, supraventricular extrasystole, and ventricular extrasystole, which were accompanied by a significant increase in heart rate and a significant decrease in total power and low- and high-frequency power of heart rate variability, during 3 days of observation after the toxin administration. However, the occurrence of arrhythmia with conduction disturbance such as second-degree atrioventricular blocks was markedly diminished by pretreatment with atropine, while the occurrence of ventricular extrasystole was augmented by atropine. The present study with the telemetric measurement elucidated and confirmed that T-2 toxin produced significant cardiac dysfunctions involving disturbance of the conduction pathway influenced by the autonomic nervous activity and also possible direct effects on cardiac myocytes.

‘Silent’ Prinzmetal’s ST Elevation Related to Atenolol Overdose

Prinzmetal's angina is a condition characterized by chest pain, transient ST elevation, and negative biochemical markers of myocardial cell necrosis. We describe a case of chemically-induced "silent" ST segment elevation related to Atenolol overdose in a patient without coronary artery stenosis. We conclude that the cause for the transient myocardial ischemia is coronary vasospasm, precipitated by beta-blocker overdose.

Cardiovascular toxicity due to metoprolol poisoning in a patient with coronary artery disease

AIM

To demonstrate that beta-blocker poisoning results in cardiovascular and central nervous system findings.

METHODS

A 56-year-old woman was brought to the emergency department, having been admitted to hospital with 1500 mg of metoprolol ingestion 2 h previously. She had undergone percutaneous transluminal coronary angioplasty and stenting because of acute myocardial infarction (AMI). Her ECG revealed ST segment elevation in inferior leads and junctional dysrhythmia. Her clinical symptoms relieved after pacing and hospitalization and she was discharged.

RESULTS

Our patient demonstrated findings of AMI with hypotension and bradycardia that appeared to result from metoprolol poisoning. Although one patient has been reported to have AMI associated with metoprolol poisoning, our patient is unique with her ECG changes and elevated cardiac markers: this is the first time that AMI characterized by elevated cardiac markers associated with metoprolol toxicity has been reported.

CONCLUSIONS

Emergency physicians should bear in mind that AMI can accompany the presentation of metoprolol overdose in those with coronary artery disease. In other words, metoprolol poisoning can trigger myocardial ischaemia and dysrhythmia in those with coronary artery disease.

ECG Manifestations: The Poisoned Patient

Despite that drugs have widely varying indications for therapeutic use, many unrelated drugs share a common cardiac pharmacologic effect if taken in overdose. The purpose of this article is to group together agents that cause similar electrocardiographic effects,review their pharmacologic actions, and discuss the electrocardiographic findings reported in the medical literature.

A Critical Reconsideration of the Clinical Effects and Treatment Recommendations for Sodium Channel Blocking Drug Cardiotoxicity

The cardiac sodium channel is comprised of proteins that span the cardiac cell membrane and form the channel pore. Depolarisation causes the proteins to move and open the sodium channel. Once the channel is open (active conformation), sodium ions move into the cell. The channel then changes from the active conformation to an inactive conformation - the channel remains open, but influx of sodium ions ceases. Recovery occurs as the channel moves from the inactive conformation back to the closed conformation and is then ready to open following the next depolarisation. Sodium channel blocking drugs (NCBDs) occupy receptors in the channel during the active and inactive conformations. The drug dissociates from most of the channel receptors during recovery, but the time it takes the drug to dissociate slows recovery. The slowed recovery prolongs conduction time, the main toxicity of NCBD overdose. Conduction time is further prolonged if heart rate increases as there are more available active and inactive conformations/unit time, which increases channel receptor binding sites for the NCBD. In addition to prolonging conduction time, NCBDs also decrease inotropy. Treatment of NCBD cardiotoxicity has been based on in vitro and animal experiments, and case reports. Assumptions based on this evidence must now be reassessed. For example, canines consistently develop ventricular tachycardia (VT) when tricyclic antidepressants (TCAs) are administered. Much of the literature discussing NCBD cardiotoxicity assumes that TCA poisoning induces VT in humans with the same regularity that occurs in canines. Seemingly, in support of this assumption was the finding that patients with remote myocardial infarction developed VT when therapeutically ingesting a NCBD. However, conduction is prolonged in myocardium that is or has been ischaemic. NCBD prolong conduction more in previously ischaemic myocardium than in normal myocardium, which causes nonuniform conduction and allows the development of re-entrant arrhythmias such as VT. Although some nonuniform conduction may occur in the healthy heart following a NCBD overdose, there is no evidence that nonuniform conduction occurs to the extent that it will cause re-entrant arrhythmias in this setting. Using various animal models and a variety of NCBDs, sodium ions, bicarbonate ions and alkalosis have been compared for the treatment of ventricular arrhythmias, hypotension and mortality. The results of these experiments have been extrapolated to NCBD overdose in humans. Animal models and single treatment approaches may have narrowed our scope. More recent evidence indicates that properties of each individual NCBD may require unique treatment. There is limited evidence that glucagon, which increases initial sodium ion influx into the cardiac cell, should be considered early in the treatment of cardiotoxicity. Another consideration may be treatment of NCBD with faster kinetics. Conduction time is decreased if a NCBD occupying the receptor is replaced by a NCBD that moves off and on the receptor more quickly. There is less evidence for this treatment, as risk may be greater. With greater understanding of the sodium channel and NCBDs, we must reassess our approach to the treatment of patients with healthy hearts who overdose on NCBD.

Cardiovascular challenges in toxicology

The diagnoses and subsequent treatment of poisoned patients manifesting cardiovascular compromise challenges the most experienced emergency physician. Numerous drugs and chemicals cause cardiac and vascular disorders. Despite widely varying indications for therapeutic use, many agents share a common cardiovascular pharmacologic effect if taken in overdose. Standard advanced cardiac life support protocol care of these patients may not apply and may even result in harm if followed. This chapter discusses com-mon cardiovascular toxins and groups them into their common mechanisms of toxicity. Multiple agents exist that result in human cardiovascular toxicity. The management of the toxicity of each agent should follow a rationale approach. The first step in the care of all poisoned patients focuses on good supportive care.

Propranolol intoxication revealing a Brugada syndrome

This is the first report of Brugada syndrome revealed by beta-blocker intoxication. A 24-year-old healthy man ingested propranolol (2.28 g) to commit suicide. After early gastric lavage, electrolytes, cardiac enzymes, chest X-ray, and echocardiography were normal. Dosages of psychotropic drugs were negative. ECG showed a typical coved-type pattern of Brugada syndrome. Follow-up showed partial ECG normalization of the discrete saddleback-type pattern. The ajmaline- test confirmed Brugada syndrome. These ECG modifications may be explained by the stabilizing membrane effect of high concentration of propranolol and/or inhibition of ICaL. This case illustrates the possible deleterious effects of beta-blockers in patients with Brugada syndrome.

Are 1–2 tablets dangerous? Beta-blocker exposure in toddlers

The common use and wide availability of beta-adrenergic blocking agents make them frequent ingestants for small children. Yet, there are no clear guidelines in the literature to direct the care of the toddler with the history of ingesting 1-2 tablets. With 40 years of extensive clinical experience, not one documented case of death or serious cardiovascular morbidity as a direct result of a beta-blocker exposure is to be found in an English language review for children under 6 years of age. As with children on chronic beta-blocker therapy, several cases of symptomatic hypoglycemia associated with a single acute propranolol exposure suggest a vulnerability to this complication. Though the risk to the toddler exposed to 1-2 tablets appears to be extremely small, several factors mitigate the actual risk to the child and the need for triage to a health care facility.

Pharmacology, Pathophysiology and Management of Calcium Channel Blocker and ??-Blocker Toxicity

Calcium channel blockers (CCB) and beta-blockers (BB) account for approximately 40% of cardiovascular drug exposures reported to the American Association of Poison Centers. However, these drugs represent >65% of deaths from cardiovascular medications. Yet, caring for patients poisoned with these medications can be extremely difficult. Severely poisoned patients may have profound bradycardia and hypotension that is refractory to standard medications used for circulatory support.Calcium plays a pivotal role in cardiovascular function. The flow of calcium across cell membranes is necessary for cardiac automaticity, conduction and contraction, as well as maintenance of vascular tone. Through differing mechanisms, CCB and BB interfere with calcium fluxes across cell membranes. CCB directly block calcium flow through L-type calcium channels found in the heart, vasculature and pancreas, whereas BB decrease calcium flow by modifying the channels via second messenger systems. Interruption of calcium fluxes leads to decreased intracellular calcium producing cardiovascular dysfunction that, in the most severe situations, results in cardiovascular collapse.Although, CCB and BB have different mechanisms of action, their physiological and toxic effects are similar. However, differences exist between these drug classes and between drugs in each class. Diltiazem and especially verapamil tend to produce the most hypotension, bradycardia, conduction disturbances and deaths of the CCB. Nifedipine and other dihydropyridines are generally less lethal and tend to produce sinus tachycardia instead of bradycardia with fewer conduction disturbances.BB have a wider array of properties influencing their toxicity compared with CCB. BB possessing membrane stabilising activity are associated with the largest proportion of fatalities from BB overdose. Sotalol overdoses, in addition to bradycardia and hypotension, can cause torsade de pointes. Although BB and CCB poisoning can present in a similar fashion with hypotension and bradycardia, CCB toxicity is often associated with significant hyperglycaemia and acidosis because of complex metabolic derangements related to these medications. Despite differences, treatment of poisoning is nearly identical for BB and CCB, with some additional considerations given to specific BB. Initial management of critically ill patients consists of supporting airway, breathing and circulation. However, maintenance of adequate circulation in poisoned patients often requires a multitude of simultaneous therapies including intravenous fluids, vasopressors, calcium, glucagon, phosphodiesterase inhibitors, high-dose insulin, a relatively new therapy, and mechanical devices. This article provides a detailed review of the pharmacology, pathophysiology, clinical presentation and treatment strategies for CCB and BB overdoses.

Poisonings and overdoses in the intensive care unit: General and specific management issues

OBJECTIVE

To provide current information on general and specific interventions for overdoses likely to require intensive care.

DESIGN

Review of literature relevant to selected interventions for general management of overdoses and specific poisons.

RESULTS

The benefit of interventions to decrease absorption or enhance elimination of toxins is limited to a relatively small number of specific agents. Antidotes and certain interventions may be helpful in preventing or treating toxicity in specific poisonings when used appropriately. Intensive supportive care is also necessary to achieve good outcomes.

CONCLUSION

Knowledge of the indications and limitations of current interventions for poisonings and overdoses is important for care of the critically ill poisoned patient.