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.

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.

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.

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.

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.

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.

Hydroxyzine-induced Torsade de Pointes in a Patient with Complete Atrioventricular Block

An 82-year-old woman was admitted to our hospital because of dyspnea and bradycardia during exertion. Electrocardiography revealed complete atrioventricular block. During pacemaker implantation, a small dose (12.5 mg) of hydroxyzine was injected for sedation, and torsade de pointes (Tdp) occurred. The QT interval was prolonged after administration of hydroxyzine, and Tdp was observed after the R on T phenomenon occurred, indicating that hydroxyzine was capable of prolonging the QT interval and causing Tdp. Therefore, we must be cautious when administering hydroxyzine for sedation during surgery, especially in patients with bradycardia.

Second-degree atrioventricular block after administration of methylergometrine for treatment of uterine atony during cesarean section

Mortality due to cardiovascular disease in pregnancy is a growing problem in developed countries, being nowadays the leading cause of maternal death. Within this group, the most common cause of death are congenital or acquired heart diseases, representing a challenge in the management of these patients, since the pregnancy-related physiological alterations can impair their basal condition and treatment. We present the case of a 34-year-old patient, without any relevant pathological antecedents, who developed a second-degree atrioventricular block, Mobitz type I, following the administration of methylergometrine during cesarean section due to failure to progress in labour. We emphasize the importance of considering the side effects of commonly used drugs in pregnant patients, despite rare possibility of some adverse reactions.

Intrinsic Electrical Remodeling Underlies Atrioventricular Block in Athletes

[Figure: see text].

Mobitz Type II Atrioventricular Heart Block After Candlenut Ingestion

The candlenut is a highly accessible seed marketed as a natural weight-loss supplement. However, there is little known about the exact mechanism of action for weight loss nor for the many adverse symptoms it causes, such as nausea, vomiting, fatigue, cardiac dysrhythmias, and even death. In this case report, the authors present a 44-year-old woman who developed a second-degree, Mobitz type II atrioventricular block after consumption of a candlenut supplement. She presented to the emergency department with syncope and her cardiac rhythm indicated a second-degree heart block soon after ingesting candlenuts recommended by her treating physician. Interestingly, a detectable digoxin concentration obtained on hospital day 2 was measured but of unclear significance given no obvious exposure to a cardioactive glycoside. The patient's rhythm normalized on hospital day 2 and she was discharged uneventfully.

Electrocardiographic findings of methanol toxicity: a cross-sectional study of 356 cases in Iran

BACKGROUND

Methanol is widely used in industry; however, methanol poisoning is not common. In this regard, a number of outbreaks have been recently reported due to inappropriate processing of alcoholic beverages. Shiraz, a city located in the southern part of Iran, faced one of such outbreaks in 2020 during COVID-19 pandemic. There is no sufficient literature on the electrocardiographic findings in methanol toxicity. This study aimed to address this gap in the literature.

METHOD

A total of 356 cases with methanol toxicity referred to Shiraz University of Medical Science Tertiary Hospitals (Faghihi and Namazi) in March and April, 2020. The clinical findings of blindness and impaired level of consciousness, lab data such as arterial blood gas, electrolytes, and creatinine, and the most common findings from ECGs were collected.

RESULTS

The most common ECG findings were J point elevation (68.8%), presence of U wave (59.2%), QTc prolongation (53.2% in males and 28.6% in females), and fragmented QRS (33.7%). An outstanding finding in this study was the presence of myocardial infarction in 5.3% of the cases. This finding, to the best of our knowledge, has only been reported in a few case reports. Brugada pattern (8.1%) and Osborn wave (3.7%) were the other interesting findings. In multivariate analysis, when confounding factors were adjusted, myocardial infarction, atrioventricular conduction disturbances, sinus tachycardia, and the prolonged QTC > 500 msecond were four independent factors correlated with methanol toxicity severity measured with arterial blood PH on arterial blood gas measurements, with odds ratios of 12.82, 4.46, 2.32 and 3.15 (P < 0.05 for all), respectively.

CONCLUSION

Electrocardiographic variations during methanol intoxication are remarkable and well-correlated with poisoning severity. Myocardial infarction was an egregious and yet a common concerning finding in this sample, which need to be ruled out in methanol toxicity.

Incidence of atrioventricular block with vasodilator stress SPECT: A meta-analysis

BACKGROUND

Adenosine or regadenoson are often used with pharmacologic stress testing. Adenosine may trigger atrioventricular block (AVB). Despite its higher selectivity, regadenoson has also been associated with AVB. We studied the incidence of de novo AVB with these agents.

METHODS

A comprehensive search of SCOPUS was performed from inception to March 2016. Studies of at least 10 patients, using adenosine and/or regadenoson with SPECT-MPI, reporting rates of AVB were selected for further review.

RESULTS

Thirty four studies were pooled including 22,957 patients. Adenosine was used in 21 studies and regadenoson in 15. Both were administered in two studies. The estimated incidence of overall and high-grade AVB was 3.81% (95% CI 1.99%-6.19%) and 1.93% (95% CI 0.77%-3.59%), respectively. The incidence of AVB (8.58%; 95% CI 5.55%-12.21% vs 0.30%; 95% CI 0.04%-0.82%, respectively, P < .001) and high-grade AVB (5.21%; 95% CI 2.81%-8.30% vs 0.05%; 95% CI < .001%-0.19% respectively, P < .001) were higher with adenosine compared to regadenoson.

CONCLUSION

AVB is seen in about 4% of patients undergoing vasodilator stress test. Both overall and high-grade AVB are more frequent with adenosine compared to regadenoson.

Complete Atrioventricular Block Associated with Pembrolizumab-induced Acute Myocarditis: The Need for Close Cardiac Monitoring

Pembrolizumab, a humanized monoclonal IgG4 antibody directed against programmed death-1, is an immune checkpoint inhibitor that has been introduced for the treatment of non-small-cell lung cancer. However, immune checkpoint inhibitors may cause severe immune-related adverse events. We herein present a case of lung cancer with complete atrioventricular block associated with acute myocarditis, which developed 16 days after the administration of pembrolizumab. The clinical course of this case suggested a strong need for close cardiac monitoring when pembrolizumab is administered on an outpatient basis.

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Zusammenfassung. Wir präsentieren den Fall einer 23-jährigen Patientin, die in suizidaler Absicht Blätter des Roten Fingerhutes sammelte und einnahm. Trotz Einnahme einer relevanten Dosis hatte sie jedoch nur geringe Symptome. Intoxikationen mit Herzglykosiden sind selten, können aber relevante Herzrhythmusstörungen verursachen. Die einzige wirksame Behandlung stellt die frühzeitige und ggf. prophylaktische Gabe von digitalisspezifischen Fab-Antikörpern dar.

Transient sick sinus syndrome with complete atrioventricular block associated with ergonovine intake: A case report

RATIONALE

More mature or older women are more likely to undergo in vitro fertilization and embryo implant. These women have a greater chance of receiving ergonovine therapy because of a suspected abortion. We present this case report to call attention to a latent lethal adverse effect in everyday obstetric practice using ergonovine. It requires more attention and close monitoring PATIENT CONCERNS:: We presented the case of a 38-year-old female patient with general weakness and mild chest tightness after ergonovine use.

DIAGNOSES

She was diagnosed as transient sick sinus syndrome and complete atrioventricular block with junctional escape rhythm after diagnostic work up.

INTERVENTIONS

Conservative treatment with discontinuation of ergonovine and bed rest.

OUTCOMES

Her sinus rhythm returned to normal the day after ergonovine was discontinued. The patient remained symptom-free since recovery of her sinus rhythm.

LESSONS

Ergonovine may cause symptomatic and lethal bradyarrhythmia. Withdrawal of the causative medication and adequate supportive care can lead to a favorable outcome in these patients. More related cases should be reported. Further evaluation for treatment and prognosis are necessary.

Mobitz type I and II atrioventricular blocks during fingolimod therapy

We investigated patients who showed a second-degree atrioventricular block (S-AVB) after the first fingolimod administration. We observed six patients with S-AVB, three Mobitz type I, and three type II. Monitoring continued on the second day for all patients. Three patients showed persistence of the S-AVB, with resolution on the second or third day. One patient had a persistent S-AVB up to the fourth day when fingolimod was discontinued. We conclude that Mobitz type II S-AVB is possible during fingolimod therapy. Patients with S-AVB could be monitored until resolution of the S-AVBs, as these may persist several days after the first fingolimod administration.

Acute colchicine intoxication complicated with complete AV block

Colchicine, is an old and well-known drug, used for treatment of rheumatic diseases. Nausea, vomiting, abdominal pain, and diarrhea are the clinical symptoms of colchicine poisoning. Cardiotoxicity can lead to mortality. We report a case of colchicine intoxication complicated with complete heart block. A 9-year-old patient ingesting colchicine 0.4-0.5 mg/kg was transferred because of elevation of liver enzymes, and deterioration of kidney functions and cytopenia. History of colchicine ingestion had been unknown at time of admission. After initial fluid and electrolyte treatment electrolyte imbalance ameliorated but kidney and liver functions worsened. In the third day of admission (7th day of ingestion), she confessed taking colchicine pills. Her state of consciousness became comatose and endotracheal intubation required. She developed complete heart block requiring temporary transvenous pacemaker implantation in the fifth day of admission. One day after pacemaker implantation, cardiopulmonary arrest developed again and remained completely unresponsive to CPR, and died. Cardiotoxicity of colchicine is leading cause of mortality. Tachycardia and conduction anomalies are not rare, but complete AV block in pediatric patient has never been reported. Although underlying mechanism is not known colchicine may have a direct toxic effect on conduction.

All-trans retinoic acid-induced, life-threatening complete atrioventricular block

We report a case of complete atrioventricular block (CAVB) with ventricular asystole and recurrent AVBs due to all-trans retinoic acid (ATRA). A 57-year-old man with acute promyelocytic leukemia was undergoing induction therapy with ATRA and developed episodic seizures with altered consciousness on the 14(th) day and then CAVB followed by cardiac arrest on the 15(th) day. Although he initially recovered after resuscitation, he suffered from recurrent CAVB, which persisted for 3 days despite immediate ATRA discontinuation. He then received ATRA retreatment with reduction of dosage, but a high-degree AVB recurred on the 5(th) day. After discontinuation of ATRA therapy, the patient recovered 3 days later without any cardiovascular event during follow-up. The serial electrocardiogram changes suggested an infra-Hisian block with possible ATRA dose-response relationship. To our knowledge, this is the first established case of ATRA-induced CAVB in the literature. We suggest clinical alertness for this life-threatening complication.

Atropine sulfate for treatment of bradycardia in a patient with morbid obesity: what may happen when you least expect it

A 74-year-old morbidly obese man was scheduled for surgical repair of an incisional ventral hernia. Anaesthesia was induced with propofol and fentanyl, and maintained with desflurane. A second dose of fentanyl 0.2 mg, given before starting surgery, resulted in sinus bradycardia and mild decrease of arterial blood pressure. Atropine sulfate 0.5 mg was administered. One minute later, the ECG rhythm on the monitor changed to third degree atrioventricular block with a ventricular response rate of 40 beats/min associated with marked hypotension. Isoproterenol 0.02 mg reverted the atrioventricular block to sinus rhythm. Cardiac enzymes and ECG ruled out acute myocardial ischaemia. The surgical procedure and the recovery from anaesthesia were uneventful. The patient was discharged from the hospital on the fifth postoperative day. For the treatment of bradycardia atropine sulfate should be adjusted at least to lean body weight in order to avoid paradoxical heart rate response in patients with obesity.

Novel OCT flushing technique for complex scenarios: imaging during iatrogenic transient AV block induced by intracoronary adenosine

We report the application of a novel optical coherence tomography (OCT) flushing technique where OCT run was performed during transient complete atrioventricular block induced by intracoronary bolus of adenosine. This technique may allow lower hydraulic force needed for contrast flush and reduce artifacts, with consequently improved OCT imaging in demanding clinical scenarios.

The incidence and predictors of overall adverse effects caused by low dose amiodarone in real-world clinical practice

BACKGROUND/AIMS

Most current knowledge regarding amiodarone toxicity derives from clinical trials. This study was performed to investigate the incidence and risk factors of overall adverse effects of amiodarone in real-world practice using a large sample size.

METHODS

Between January 1, 2000 and March 10, 2012, a total of 930 consecutive patients who had been treated with amiodarone for arrhythmia were reviewed retrospectively. An amiodarone-associated adverse event was considered in cases of discontinuation or drug dose reduction due to an unexpected clinical response.

RESULTS

The mean daily dose of amiodarone was 227 ± 126 mg, and the mean duration was 490 ± 812 days. During the mean follow-up duration of 982 ± 1,137 days, a total of 154 patients (16.6%) experienced adverse effects related to amiodarone, the most common being bradycardia or conduction disturbance (9.5%). Major organ toxicities in the thyroid (2.5%), liver (2.2%), eyes (0.6%), and lungs (0.3%) were rare. All patients recovered fully without complications after amiodarone discontinuation or dose reduction. The only independent predictor of adverse effects was the duration of amiodarone treatment (odds ratio, 1.21; 95% confidence interval, 1.03 to 1.41; p = 0.016, per year).

CONCLUSIONS

Low-dose amiodarone is well tolerated in a real-world clinical population. Further studies with a prospective design are needed to confirm this finding.

Case of Wenckebach-type atrioventricular block caused by administration of indigo carmine

We report a case of first-degree atrioventricular (A-V) block progressing to second-degree (Wenckebach-type) A-V block after administration of indigo carmine in a patient undergoing hysterectomy under general anesthesia. We believe that the onset of Wenckebach-type A-V block may have been induced by one or more of three factors: 1) preoperative first-degree A-V block, 2) the anesthetics used (propofol and remifentanil), and 3) administration of indigo carmine.

[Incomplete atrioventricular block in a patient on pregabalin therapy]

The authors report on a case of incomplete atrio-ventricular block in a patient on pregabalin therapy. Pregabalin was not overdosed; renal function of the patient was normal. The effect reverted after pregabalin discontinuation.

Desensitization by progressive up-titration prevents first-dose effects on the heart: guinea pig study with ponesimod, a selective S1P1 receptor modulator

Ponesimod, a selective S1P₁ receptor modulator, reduces the blood lymphocyte count in all tested species by preventing egress of T and B cells from thymus and peripheral lymphoid organs. In addition, ponesimod transiently affects heart rate and atrioventricular (AV) conduction in humans, effects not observed in mice, rats, and dogs with selective S1P₁ receptor modulators, suggesting that the regulation of heart rate and rhythm is species dependent. In the present study, we used conscious guinea pigs implanted with a telemetry device to investigate the effects of single and multiple oral doses of ponesimod on ECG variables, heart rate, and blood pressure. Oral administration of ponesimod did not affect the sinus rate (P rate) but dose-dependently induced AV block type I to III. A single oral dose of 0.1 mg/kg had no effect on ECG variables, while a dose of 3 mg/kg induced AV block type III in all treated guinea pigs. Repeated oral dosing of 1 or 3 mg/kg ponesimod resulted in rapid desensitization, so that the second dose had no or a clearly reduced effect on ECG variables as compared with the first dose. Resensitization of the S1P₁ receptor in the heart was concentration dependent. After desensitization had been induced by the first dose of ponesimod, the cardiac system remained desensitized as long as the plasma concentration was ≥75 ng/ml. By using a progressive up-titration regimen, the first-dose effect of ponesimod on heart rate and AV conduction was significantly reduced due to desensitization of the S1P₁ receptor. In summary, conscious guinea pigs implanted with a telemetry device represent a useful model to study first-dose effects of S1P₁ receptor modulators on heart rate and rhythm. This knowledge was translated to a dosing regimen of ponesimod to be tested in humans to avoid or significantly reduce the first-dose effects.

Atazanavir induced first degree atrioventricular block and ventricular tachycardia: a case report

Atazanavir is one highly active antiretroviral therapy for naïve patients or patients with previous regimen failure. However, it seems that the protease inhibitor induces hyperlipidemia. Hyperbillirubinemia is the most common clinical adverse events but reports of cardiotoxicity due to atazanavir are scarce. The authors report a patient who had QT prolongation, first-degree atrioventricularblock, and ventricular tachycardia. After atazanavir/ritonavir discontinuation, this patient got better and had normal electrocardiography. Lopinavir/ritonavir was carefully reintroduced during hospitalization without any adverse drug reaction. Atazanavir induced cardiotoxicity has to be monitored when using protease inhibitors.

Transient, high-grade atrioventricular block from high-dose cyclophosphamide

Cyclophosphamide, an alkylation agent, is widely used in stem cell transplantation for its antineoplastic and myeloablative properties. Congestive heart failure, pericarditis, and arrhythmias are well-known cardiac sequelae of high-dose cyclophosphamide therapy; however, high-grade atrioventricular block has rarely been reported. We present the case of a 71-year-old man who developed a high degree of atrioventricular block several hours after therapy with high-dose cyclophosphamide. After treatment with a temporary pacemaker and cessation of cyclophosphamide, the patient experienced no more events. Before administering cyclophosphamide, evaluating patients for underlying conduction abnormalities is advisable. Agents other than cyclophosphamide are available.

[Clinical significance of the cardiovascular effects of fingolimod treatment in multiple sclerosis]

Fingolimod is a sphingosine-1 phosphate receptor modulator, which is effective in the treatment of severe relapsing-remitting form of multiple sclerosis. Once daily oral use of fingolimod decreased the annualized relapse rate, inflammatory brain lesion activity and the rate of brain atrophy compared both to placebo and intramuscular administered interferon beta-1a. The drug targets the cardiovascular system as well via sphingosine-1 phosphate receptors. After initiation of fingolimod therapy transient sinus bradycardia and slowing of the atrioventricular conduction develops. The onset of the effect is as early as 1 hour post administration, while heart rate and conduction normalized in 24 hours in most of the cases. According to the clinical trials symptomatic bradycardia developed in 0.5% of the cases, responding to the appropriate therapy. The incidence of Mobitz I type II atrioventricular blocks and blocks with 2:1 atrioventricular conduction was 0.2% and 0.1%, respectively. All of these cardiovascular events showed regression during observation and no higher degree atrioventricular blocks were detected at the approved therapeutic dose. Following the first dose effect, fingolimod had a moderate hypertensive effect on long-term. For the safety of fingolimod treatment detailed cardiovascular risk stratification of all patients, adequate patient monitoring after the first dose and competency in treating the possible side effects is necessary. In patients with increased cardiovascular risks, treatment should be considered only if anticipated benefits outweigh potential risks and extended monitoring is required.

Complete atrioventricular block caused by mad honey intoxication

The honey produced by the bees fed on Rhododendron family plants containing grayanotoxin is known as mad honey in our country. This intoxication is seen rarely. However, it may lead life-threatening hemoinstability mentioned above and may be confused with various diseases. For these reasons the exact diagnosis and treatment of this intoxication seems very important. We aim to describe a case admitted to the Emergency Department in consequence of mad honey intoxication and treated and discharged after hypotension and complete atrioventricular block development.

Grayanotoxin poisoning: 'mad honey disease' and beyond

Many plants of the Ericaceae family, Rhododendron, Pieris, Agarista and Kalmia, contain diterpene grayanotoxins. Consumption of grayanotoxin containing leaves, flowers or secondary products as honey may result in intoxication specifically characterized by dizziness, hypotension and atrial-ventricular block. Symptoms are caused by an inability to inactivate neural sodium ion channels resulting in continuous increased vagal tone. Grayanotoxin containing products are currently sold online, which may pose an increasing risk. In humans, intoxication is rarely lethal, in contrast to cattle and pet poisoning cases. Scientific evidence for the medicinal properties of grayanotoxin containing preparations, such as honey or herbal preparation in use in folk medicine, is scarce, and such use may even be harmful.

Anticholinesterase-induced symptoms improved by pacemaker implantation in patients with Alzheimer's disease: analysis of 6 cases

Herein we describe 6 cases of patients with Alzheimer's disease presented with syncope, dizziness, and dyspnea soon after the initiation of cholinesterase inhibitor therapy. All patients had bradyarrhythmia on electrocardiogram (ECG). Two patients had complete atrioventricular block, 2 pateints had 2/1 type atrioventricular block, 1 patient had sinus bradycardia and hypersensitive carotid sinus syndrome, and 1 had sick sinus syndrome. All these patients were treated with pacemaker implantation and the cholinesterase inhibitor therapy continued. At 13-month follow-up, no syncope, dizziness, or dyspnea was reported.

Complete atrioventricular block due to overdose of pregabalin

Pregabalin, a synthetic derivate of the inhibitory neurotransmitter γ-aminobutyric acid, shows antiepileptic, analgesic, anticonvulsant, anxiolytic, and sleep-modulating activities. The major advantage of pregabalin is its relative reliability, easy use, high tolerance, and lack of negative interaction with other drugs. A 65-year-old woman with medical histories of diabetes mellitus, lumbar spondylosis, diabetic nephropathy, chronic renal failure, and anemia of chronic disease was admitted with the complaint of dizziness and syncope. She had been taking pregabalin 300 mg daily for 8 months. Electrocardiogram revealed complete atrioventricular (AV) block and right bundle-brunch block with a heart rate of 39 per minute. Her creatinine was 1.8 mg/dL, and creatinine clearance was 50 mL/min. Pregabalin treatment was discontinued. Four days later, the complete AV block resolved spontaneously to Mobitz type II block and to sinus rhythm with right bundle-brunch block on the seventh day. To our knowledge, this is the first case of complete AV block associated with pregabalin. We believe that AV block occurred as a result of pregabalin's effect on L-type Ca++ channels in the heart. Pregabalin's different effects on electrocardiogram and on the heart in different individuals may have an association with the patterns of distribution of the L-type calcium channels in myocardium.

[Kounis syndrome secondary to an allergic reaction to metamizole]

Severe cardiovascular events, such as coronary vasospasm or acute myocardial infarction can occur during anaphylactic reactions. Although rare, this cause of ischaemic heart disease is known. We present the case of a patient who suffered an angina episode after an anaphylactic reaction due tot administering metamizole, with no significant lesions observed in the coronary catheterisation.

"Crime scene investigation" at an anesthetic cocktail party with atrioventricular dissociation

A healthy 21-year-old female patient received midazolam, propofol, fentanyl, rocuronium, nitrous oxide in oxygen, ranitidine, diclofenac, neostigmine and glycopyrrolate during the anesthetic process for elective knee arthroscopy and developed a complete AV dissociation with a P-wave frequency of 40 and a "small" QRS-complex frequency of 55 beats/min. Based on this typical case of poly-pragmatic anesthetic drug administration causing a complete atrioventricular dissociation in a young healthy patient we will discuss the possible pharmacodynamic mechanisms of all used drugs with regard to the cardiac conduction system.

Atrioventricular block following lacosamide intoxication

Lacosamide (LCM) is a novel anticonvulsant that modulates voltage-dependent sodium channels. Although it is known to cause a slight, dose-dependent prolongation of the PR interval on the ECG, third-degree atrioventricular (AV) block has been described as an adverse event in only a few patients participating in diabetic neuropathic pain studies and in no patient with epilepsy. We describe an 89-year old patient with decreased renal function and taking two other negative dromotropic agents who accidentally received two intravenous boli of 400 mg LCM within 6 hours. She had a normal PQ interval before and after the first dose of LCM and developed a reversible complete AV block approximately 30 minutes after the second bolus. We conclude that particular caution must be exercised when using very high doses of LCM in patients with significant cardial and renal risk factors.

Complete atrioventricular block secondary to bortezomib use in multiple myeloma

Bortezomib is an inhibitor of 26S proteasome, which is an effective treatment for multiple myeloma. The common adverse effects of bortezomib are asthenic conditions, gastrointestinal disturbances, and peripheral neuropathy. Here we describe a patient with dyspnea and general weakness because of complete atrioventricular block while receiving bortezomib. We immediately stopped bortezomib, and after inserting a permanent VDD pacemaker, the patients' symptoms disappeared.

Feasibility and safety of high-dose adenosine perfusion cardiovascular magnetic resonance

INTRODUCTION

Adenosine is the most widely used vasodilator stress agent for cardiovascular magnetic resonance (CMR) perfusion studies. With the standard dose of 140 mcg/kg/min some patients fail to demonstrate characteristic haemodynamic changes: a significant increase in heart rate (HR) and mild decrease in systolic blood pressure (SBP). Whether an increase in the rate of adenosine infusion would improve peripheral and, likely, coronary vasodilatation in those patients is unknown. The aim of the present study was to assess the tolerance and safety of a high-dose adenosine protocol in patients with inadequate haemodynamic response to the standard adenosine protocol when undergoing CMR perfusion imaging.

METHODS

98 consecutive patients with known or suspected coronary artery disease (CAD) underwent CMR perfusion imaging at 1.5 Tesla. Subjects were screened for contraindications to adenosine, and an electrocardiogram was performed prior to the scan. All patients initially received the standard adenosine protocol (140 mcg/kg/min for at least 3 minutes). If the haemodynamic response was inadequate (HR increase < 10 bpm or SBP decrease < 10 mmHg) then the infusion rate was increased up to a maximum of 210 mcg/kg/min (maximal infusion duration 7 minutes).

RESULTS

All patients successfully completed the CMR scan. Of a total of 98 patients, 18 (18%) did not demonstrate evidence of a significant increase in HR or decrease in SBP under the standard adenosine infusion rate. Following the increase in the rate of infusion, 16 out of those 18 patients showed an adequate haemodynamic response. One patient of the standard infusion group and two patients of the high-dose group developed transient advanced AV block. Significantly more patients complained of chest pain in the high-dose group (61% vs. 29%, p = 0.009). On multivariate analysis, age > 65 years and ejection fraction < 57% were the only independent predictors of blunted haemodynamic responsiveness to adenosine.

CONCLUSIONS

A substantial number of patients do not show adequate peripheral haemodynamic response to standard-dose adenosine stress during perfusion CMR imaging. Age and reduced ejection fraction are predictors of inadequate response to standard dose adenosine. A high-dose adenosine protocol (up to 210 mcg/kg/min) is well tolerated and results in adequate haemodynamic response in nearly all patients.

Travelers on beta-blockers: is malaria chemoprophylaxis dangerous?

Classic antimalarial drugs, particularly quinine and its derivatives, are well known for their potential pro-arrhythmic effects. Recently developed synthetic antimalarials are widely used among travelers for prophylaxis. Nevertheless, their safety is open to question, especially for travelers under common cardiovascular drug therapy. We report the case of a patient admitted for symptomatic high-grade atrioventricular (AV) block, caused by combined therapy with a common malaria prophylactic drug--mefloquine--and a beta-blocker prescribed for a symptomatic arrhythmia. Withdrawal of the beta-blocker led to disappearance of the AV block despite continuation of the malaria prophylaxis. Mefloquine drug interactions are briefly described, particularly in terms of the caution needed in travelers already under beta-blocker therapy in whom antimalarial drug prophylaxis is recommended.

[Cardiac arrest induced by dexmedetomidine]

A 64-year-old woman with hypertension, diabetes mellitus and asymptomatic first degree AV block underwent low anterior resection of the rectum. Anesthesia was induced with propofol, vecuronium bromide and remifentanil and maintained with nitrous oxide in oxygen, propofol and remifentanil. We did not use epidural anesthesia. After the operation, the patient was admitted to the intensive care unit under general anesthesia with propofol and remifentanil. In addition, dexmedetomidine was given without loading dose. The EKG changed from first degree AV block to second degree AV block followed by complete AV block and finally cardiac arrest. As soon as we performed heart massage, sinus rhythm appeared. We should be careful in giving dexmedetomidine to a patient with AV block.