Autonomic function and ventricular tachyarrhythmias during acute myocardial infarction

Most cases of sudden cardiac death are attributed to sustained ventricular tachyarrhythmias(VTs), triggered by acute coronary occlusion. Autonomic dysfunction, an important arrhythmogenic mechanism in this setting, is being actively investigated, aiming at the advent of preventive strategies. Recent experimental studies have shown vagal withdrawal after anterior myocardial infarction, coinciding with high incidence of VTs, followed by more gradual sympathetic activation coinciding with a second arrhythmia peak. This article summarizes recent knowledge on this intriguing topic, generating hypotheses that can be investigated in future experimental and clinical studies.

Landiolol, an ultra-short-acting β1-blocker, is useful for managing supraventricular tachyarrhythmias in sepsis

AIM: To investigate whether landiolol, an ultra-shortacting β1-antagonist, can safely and effectively control heart rate in septic patients with supraventricular tachyarrhythmias.METHODS: We reviewed all patients with sepsis who admitted to our intensive care unit between January 2006 and December 2011. Sixty one septic patients suffered from supraventricular tachyarrhythmias(heart rate ≥ 120 bpm for > 1 h). Among 61 patients, 39 patients were treated with landiolol(landiolol group) and 22 patients were not treated with landiolol(control group). Arterial pressure, heart rate, cardiac rhythm, pulmonary arterial pressure and cardiac output(if a pulmonary arterial catheter was inserted) were compared between the 2 groups at 1, 8 and 24 h after the initiation of tachyarrhythmias. RESULTS: Mean age and Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores were similar between the 2 groups. Paroxysmal atrial fibrillation/flutter(87%), paroxysmal atrial tachycardia(10%), and paroxysmal supraventricular tachycardia(3%) were observed. The initial landiolol dose administered was 6.3 ± 5.8 g/kg per minute. Rapid and substantial reduction of heart rate was observed in the landiolol group without anydeterioration of hemodynamics. Landiolol significantly reduced heart rate(from 145 ± 14 bpm to 90 ± 20 bpm) compared to the control group(from 136 ± 21 bpm to 109 ± 18 bpm, P < 0.05). The conversion to sinus rhythm was observed more frequently in the landiolol group than in the control group at every point(P < 0.01 at 8 h; P < 0.05 at 1 and 24 h).CONCLUSION: Landiolol safely reduced heart rate and, in part, converted to sinus rhythm in septic patients with supraventricular tachyarrhythmias.

Microvolt T-wave alternans complemented with electrophysiologic study for prediction of ventricular tachyarrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy: a long-term follow-up study

Background: The long-term predicted value of microvolt T-wave alternans (MTWA) for ventricular tachyarrhythmia in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) remains unclear. Our study explored the characteristics of MTWA and its prognostic value when combined with an electrophysiologic study (EPS) in patients with ARVC. Methods: All patients underwent non-invasive MTWA examination with modified moving average (MMA) analysis and an EPS. A positive event was defined as the first occurrence of sudden cardiac death, documented sustained ventricular tachycardia (VT), ventricular fibrillation, or the administration of appropriate implantable cardioverter defibrillator therapy including shock or antitachycardia pacing. Results: Thirty-five patients with ARVC (age 38.6 ± 11.0 years;28 males) with preserved left ventricular (LV) function were recruited. The maximal TWA value (MaxValt) was 17.0 (11.0–27.0)μV. Sustained VT was induced in 22 patients by the EPS. During a median follow-up of 99.9 ± 7.7 months, 15 patients had positive clinical events. When inducible VT was combined with the MaxValt, the area under the curve improved from 0.739 to 0.797. The receiver operating characteristic curve showed that a MaxValt of 23.5 μV was the optimal cutoff value to identify positive events. The multivariate Cox regression model for survival showed that MTWA (MaxValt, hazard ratio [HR], 1.06;95% confidence interval [CI], 1.01–1.11;P = 0.01) and inducible VT (HR, 5.98;95% CI, 1.33–26.8;P = 0.01) independently predicted positive events in patients with ARVC. Conclusions: MTWA assessment with MMA analysis complemented by an EPS might provide improved prognostic ability in patients with ARVC with preserved LV function during long-term follow-up.

Renal artery denervation suppresses intractable ventricular arrhythmia in patients with left heart thrombosis

Transcutaneous renal artery denervation （RND） has beeninitially developed for destruction of efferent nerve fireswith luminal delivery of radiofrequency or ultrasonic energyaiming blood pressure reduction in patients with refractoryhypertension. However, other positive results of RNDwere described afterwards, and they include suppression ofatrial fibrillation and ventricular tachycardia （VT） storm.

3D Non-Fluoroscopic Cryoablation of Right-Sided Accessory Pathways in Children:Monocentric Study and Literature Review

Background:Cryoablation of accessory pathways(APs)is effective and very safe in children,as previously reported by our group.The aim of this retrospective study was to evaluate the current efficacy of 3D non-fluoroscopic cryoablation of right sided APs in children,comparing results obtained with the Ensite VelocityTM and the more recent Ensite PrecisionTM 3D mapping systems.Methods and Results:From January 2016 to December 2019,102 pediatric patients[mean age 12.5±2.8,62 males(61%of total cohort)]with right APs underwent 3D non-fluoroscopic transcatheter cryoablation at our Institution.Fifteen(14.7%)patients had previously undergone catheter ablation.Acute procedural success rate was 95.1%(n=97).No significant differences were detected in acute success rates achieved with Ensite Velocity^(TM)or Ensite PrecisionTM systems nor between manifest(94%)and concealed APs(100%).No permanent complications occurred.During follow-up(428±286 days,median 396 days[interquartile range 179-713]),19 patients(19.6%)had recurrences.Recurrences were more frequent for parahissian/anterior APs compared to midseptal/posterior and lateral APs(p=0.043).Recurrences were not related to the Ensite system used.A redo ablation procedure was attempted in 13 cases,11 cryoablation and 2 radiofrequency ablations:the former was successful in 10 cases out of 11(90.9%).Conclusion:3D cryoablation of right-sided APs is associated with a very high acute success rate with limited use of fluoroscopy,resulting in great benefit to the children.Recurrence rates are not high and patients can be retreated with cryo-energy with higher success rates.

Importance of clinical suspicion and multidisciplinary management for early diagnosis of a cardiac laminopathy patient:A case report

BACKGROUND Laminopathies are rare diseases,whose cardiac manifestations are heterogeneous and,especially in their initial stage,similar to those of more common conditions,such as ischemic heart disease.Early diagnosis is essential,as these conditions can first manifest themselves with sudden cardiac death.Electrical complications usually appear before structural complications;therefore,it is important to take into consideration these rare genetic disorders for the differential diagnosis of brady and tachyarrhythmias,even when left ventricle systolic function is still preserved.CASE SUMMARY A 60-year-old man,without history of previous disorders,presented in September 2019 to the emergency department because of the onset of syncope associated with hypotension.The patient was diagnosed with a high-grade atrioventricular block.A dual chamber pacemaker was implanted,but after the onset of a sustained ventricular tachycardia during physical exertion,a drug eluting stent was implanted on an intermediate stenosis on the left anterior descending artery,which had previously been considered non-haemodynamically significant.During the follow-up,the treating cardiologist,suspicious of the overall clinical picture,recommended a genetic test for the diagnosis of cardiomyopathies,which tested positive for a pathogenetic mutation of the lamin A/C gene.While awaiting the result of the genetic test and,later,the pacemaker to be upgraded to a biventricular defibrillator,a remote monitoring device was given to the patient in 2019-related lockdown.CONCLUSIONThis case aims to raise awareness of the cardiological manifestations of laminopathies,which can be dangerously misdiagnosed as other, more common conditions.

Arrhythmogenic properties of dismantling cadherin-mediated adhesion in murine hearts

Objective： To evaluate the arrhythmogenic effects of dismantling cadherin-mediated adhesion by recombinant mouse aminopeptidase N （rmAPN） in murine hearts. Methods： rmAPN was incubated with cultured neonatal rat cardiomyocytes as well as being infused in adult mice. The cell-cell connections were immunolabelled and observed by laser confocal microscopy. Disruption of the N-terminal of N-cadherin （N-cad） was detected by western blot and quantitative immunofluorescence. The risk of inducible ventricular tachyarrhythmia was evaluated in mice by an electrophysiological study. Results： Disrupted cell-cell contact was observed in cultured neonatal rat cardiomyocytes in response to 30-40 ng/μL rmAPN. Loss of the N-terminal in N-cad and altered distribution of connexin 43 （Cx43） were observed in hearts from rmAPN-infused mice. In addition, a reduction of phosphorylated Cx43 was also detected concomitant with redistribution of Cx43. Electrophysiological studies of rmAPN-infused mice showed prolonged QRS duration and increased inducibility of ventricular tachycardias. Conclusion： Disruption of N-cad by rmAPN contributes to gap junction remodeling and may elicit arrhythmogenic effects. The disorder of adherent junctions by proteolytic enzymes may play an important role in arrhythmogenic mechanisms in correlated diseases.

Ventricular Arrhythmia in the Fontan Circulation:Prevalence,Risk Factors and Clinical Implications

Objective:Sudden cardiac death(SCD)and malignant ventricular arrhythmia(VA)are increasingly recognized as important issues for people living with a Fontan circulation,but data are lacking.We sought to characterize the cohort who had sudden cardiac death,most likely related to VA and/or documented VA in the Australia and New Zealand Fontan Registry including risk factors and clinical outcomes.Methods:A retrospective cohort study was performed.Inclusion criteria were documented non-sustained ventricular tachycardia,sustained ventricular tachycardia,ventricular fibrillation,resuscitated cardiac arrest or SCD>30 days post-Fontan completion.Results:Of 1611 patients,20(1.2%)had VA;14(1.0%)had VA without SCD and 6(<1%)had SCD(6%of all deaths recorded in Registry;5 of those had documented VA at the time of arrest and 1 was presumed to be VA-associated).The median age at first VA was 20.5(14–32)years,10(50%)were females,and the median age at Fontan operation was 8(4–17)years.On univariable analysis,hypoplastic left heart syndrome(p=0.03)and older age Fontan operation(p<0.001)were associated with VA.Earlier Fontan era(p<0.003),atriopulmonary Fontan(p<0.001),pre-Fontan atrioventricular valve repair(p=0.013)pre-or post-Fontan atrial arrhythmia(p=0.010)were associated with SCD.Patients with VA had a 3 times higher risk of death or heart transplant(HR 3.27(1.19,8.98),p=0.02).Conclusions:A proportion of people living with a Fontan circulation have malignant VA.Routine VA screening in this cohort is essential.More data are needed to aid risk stratification.

Postoperative Intensive Care Treatment after Esophageal Resection

The aim of this article is to give a short review of problems associated with the intensive care treatment of patients after esophageal resection. Pulmonary dysfunction, supraventricular tachyarrhyth- mia, anastomotic leakage and mental disorders are the topics covered. Systemic in?ammatory reaction and sepsis is the linking topic between these speci?c complications. Pulmonary dysfunction having an incidence of up to 40% is the most important complication. Low tidal volume ventilation, pain management including epidural analgesia and early tracheostomy are the mainstay of therapy. Supraventricular tachyarrhythmia is an early indicator of emerging complications. Its symptomatic treatment is standardized using electric cardioversion, beta-blockers五笔字型计算机汉字输入技术leakage must be suspect in any septic episode. and amiodarone. Anastomotic Endoscopy and contrast studies allow for precise diagnosis. Interventional endoscopy is increasingly suc- cessful in the therapy of these leakages. Microbiological surveillance and speci?c antibiotic therapy ensure that a complication does not cause a septic cascade leading to multiorgan failure. The workload on ICU caused by a patient after esophageal resection still exceeds that of most other patients with gastrointestinal surgery.

Effects of Tiaomaiyin and Its Disassembled Prescription on Expression of L-type Calcium Channel β2 Subunit in Rat Model of Tachyarrhythmia

[Objectives] To study the effects of Tiaomaiyin and its disassembled prescription on expression of L-type calcium channel β2 subunit in rat model of tachyarrhythmia. [Methods] Sixty Wistar rats were randomly divided into model group,Tiaomaiyin prescription group( whole prescription group),main efficacy group of removing heat to cool blood( blood cooling group),and auxiliary drug efficacy group of benefiting qi and nourishing heart( qi benefiting group),auxiliary efficacy group of promoting flow of qi and blood circulation( qi flow promoting group),and amiodarone group( western medicine group). Aconitine was given 7 d after the intragastric administration of the corresponding drugs,and the time of occurrence of arrhythmia in each group was observed. The left ventricular myocardium was subjected to reverse transcription-polymerase chain reaction and Western blotting. [Results] The ventricular premature beats( VPB) time in the whole prescription group and western medicine group was significantly longer than that in the model group. Ventricular tachycardia( VT),ventricular fibrillation( VF),and cardiac arrest( CA) were longer in the whole prescription group,blood cooling group,and western medicine group. The mRNA and protein expression of L-type calcium channel β2 subunit in the whole prescription group,blood cooling group and western medicine group were significantly decreased. [Conclusions] Tiaomaiyin whole prescription group and blood cooling group can reduce the occurrence time of tachyarrhythmia and reduce the expression of LTCC β2 in myocardium.

Malignant hyperthermia as a rare complication of local lidocaine injection:A case report

BACKGROUND Malignant hyperthermia(MH)is a hypermetabolic disorder of skeletal muscles triggered by exposure to volatile anesthetics and depolarizing muscular relaxants.It manifests with clinical presentations such as tachycardia,muscle rigidity,hyperpyrexia,and rhabdomyolysis in genetically predisposed individuals with ryanodine receptor or calcium voltage-gated channel subunit alpha1 S mutations.Local anesthetics,such as lidocaine,are generally considered safe;however,complications can arise,albeit rarely.Lidocaine administration has been reported to induce hypermetabolic reactions resembling MH in susceptible individuals.The exact mechanism by which lidocaine might trigger MH is not fully understood.Although some mechanisms are postulated,further research is needed for a better understanding of this.CASE SUMMARY We present the case of MH in a 43-year-old male patient with an unknown genetic predisposition following a lidocaine injection during a dental procedure.This case serves as a reminder that while the occurrence of lidocaine-induced MH is rare,lidocaine can still trigger this life-threatening condition.Therefore,caution should be exercised when administering lidocaine to individuals who may be susceptible to MH.It is important to note that prompt intervention played a crucial role in managing the patient’s symptoms.Upon recognizing the early signs of MH,aggressive measures were initiated,including vigorous intravenous normal saline administration and lorazepam.Due to the effectiveness of these interventions,the administration of dantrolene sodium,a specific antidote for MH,was deferred.CONCLUSION This case highlighted the significance of vigilant monitoring and swift action in mitigating the detrimental effects of lidocaine-induced MH.Caution should be exercised when administering lidocaine to individuals who may be predisposed to MH.It is very important to be aware and vigilant of the signs and symptoms of MH as early recognition and treatment intervention are important to prevent serious complications to decrease mortality.

Spontaneous high-frequency action potential

Action potential,which is the foundation of physiology and electrophysiology,is most vital in physiological research.This work starts by detecting cardiac electrophysiology(tachyarrhythmias),combined with all spontaneous discharge phenomena in vivo such as wound currents and spontaneous neuropathic pain,elaborates from generation,induction,initiation,to all of the features of spontaneous high-frequency action potential--SSL action potential mechanism,i.e.,connecting-end hyperpolarization initiates spontaneous depolarization and action potential in somatic membrane.This work resolves the conundrums of in vivo spontaneous discharge in tachyarrhythmias,wounds,denervation supersensitivity,neurogenic pain(hyperalgesia and allodynia),epileptic discharge and diabetic pain in pathophysiological and clinical researches that have puzzled people for a hundred years.

Calcium-handling abnormalities underlying atrial arrhythmogenesis in a Fontan operation canine model

Background Atrial tachyarrhythmia (AT) is a common complication in patients who have undergone a Fontan operation. In this study, we investigated whether abnormal Ca2+ handling contributes to the Fontan operation-related atrial arrhythmo-genic substrate. Methods Mongrel dogs were randomly assigned to sham and Fontan groups. The Fontan operation model was developed by performing an atriopulmonary anastomosis. After 14 days, an electrophysiological study was performed to evaluate the AT vulnerability. Ca2+ handling properties were measured by loading atrial cardiomyocytes (CMs) with fura-2 AM. The L-type Ca2+ (ICa?L) and Na+–Ca2+ exchanger (INCX) currents of the CMs were recorded by the whole-cell patch-clamp technique. The key Ca2+ handling proteins expression was assessed by Western blotting. Results The AT inducibility was higher in the Fontan group than in the sham group (85.71 vs. 14.29%, P < 0.05). The Fontan operation resulted in decreased Ca2+ transient (CaT) amplitude and sarcoplasmic reticulum (SR) Ca2+ content, but in enhanced diastolic intracellular Ca2+ concentration and SR Ca2+ leak in the atrial CMs. The spontaneous CaT events, triggered ectopic activity and INCX density were increased, but ICa?L density was reduced in CMs from the Fontan atria (all P<0.05). Additionally, the Fontan operation resulted in decreased SR Ca2+ ATPase expression and Cav1.2 expression, but in increased NCX1 and Ser2814-phosphorylated ryanodine receptor 2. The calmodulin-dependent protein kinase II expres-sion and function were markedly enhanced in the Fontan atria. Conclusion The Fontan operation caused atrial CM Ca2+ handling abnormalities that produced arrhythmogenic-triggered activity and increased vulnerability to AT in experimental Fontan dogs.

Incidence and causes of inappropriate detection and therapy by implantable defibrillators of cardioversion in patients with ventricular tachyarrhythmia

Background Implantable cardioverter defibrillator （ICD） is the only effective therapy in patients with life threatening ventricular arrhythmias. Inappropriate detection and therapy by ICDs are the most common causes of side effects that affect the quality of life in ICD recipients. This study evaluated the incidence and causes of inappropriate detection and therapy by ICDs in patients in our hospital. Methods From January 2000 to December 2005, fifty patients who received ICD implantation for ventricular arrhythmias for prevention of sudden cardiac death were evaluated in this study. Each ICD was programmed using clinical arrhythmic and cardiac data of the patient before discharge. Patients were followed up by standard schedule after implantation and all data retrieved from each device were collected and saved for further analysis. Results No arrhythmic event was detected in 12/50 （24%） patients during the period of follow-up. Among the remaining patients, 11 （22%） experienced inappropriate detections and therapies during follow-up in this study. ICD detected 383 ventricular tachyarrhythmia （VT） and 108 ventricular fibrillation （VF） episodes and delivered 678 therapies. In VT group, ICD delivered 413 antitachycardiac pacings （ATPs） and 118 shocks, among which 78 ATPs and 9 shocks were initiated by 55/383 （14.3%） inappropriate detections. In VF group ICD delivered 147 shocks, among which 56 shocks were initiated by 28/108 （26.9%） inappropriate detections. Overall, more than 50% of these episodes were caused by atrial fibrillation （AF） with rapid ventricular response, followed by electromagnetic or myopotential interference. In addition, most inappropriate therapies occurred within one year after ICD implantation. Conclusions About one fifth of patients experienced ICD inappropriate detection and therapy after implantation. The main cause was AF with rapid ventricular response, followed by electromagnetic or myopotential interference.

Adjunctive anti-tachycardia pacing therapy for patients with acute myocardial infarction during emergency percutaneous coronary intervention

It was reported that more than 95% arrhythmias complicated with acute myocardial infarction (AMI) occurred within the first 24 hours of AMI onset, and emergency percutaneous coronary intervention (PCI) has been worldwide applied to realize reperfusion. 1 But how to deal with tachyarrhythmia induced by ischemia and reperfusion around emergency PCI procedure, has become one of the focus during peri-PCI stage. It has been reported that anti-tachycardia pacing (ATP) termination of post AMI tachyarrhythmia by implantation of cardioverter-defibrillator (ICD) or other model of pacemaker had ideal result. 2,3 But the studies on the effect of ATP therapy for tachyarrhythmia during emergency PCI procedure were rarely reported. In this study, the effect and the safety of ATP therapy for 115 patients with tachyarrhythmia during emergency PCI procedure by implantation of temporary pacing catheter were reported.

Home monitoring system improves the detection of ventricular arrhythmia and inappropriate shock

Background The impact of home monitoring system in the early detection of ventricular arrhythmia and inappropriate shock in daily work is not clear. The aim of this study was to investigate the impact of home monitoring system on the early detection of ventricular arrhythmia and inappropriate shock in daily clinical practice. Methods Cases of implantable cardioverter defibrillator （ICD） implantation with or without the home monitoring system from June 2010 to October 2011 at our center were reviewed. Follow-up was scheduled after implantation. Data relating to the home monitoring ICD were retrieved using a remote transmitter system. Data relating to the other devices were obtained during scheduled follow-up or unscheduled visits. Results Our study involved 69 patients （mean age （68.4＋17.6） years, 64.3% males, 26 in the home monitoring group vs. 43 in the non-home monitoring group）. In all, 561 ventricular arrhythmia episodes were detected in 17 patients （39.5%） in the non-home monitoring group： 495 episodes were ventricular tachycardia and 66 episodes were ventricular fibrillation; among these, 476 episodes of ventricular tachycardia and 45 episodes of ventricular fibrillation were appropriately diagnosed （96.1% and 68.2%, respectively）. In the home monitoring group, 389 ventricular arrhythmia episodes were transmitted by the home monitoring system in nine patients （34.6%）： 348 ventricular tachycardia episodes and 41 ventricular fibrillation episodes. Device detection was appropriate in 348 ventricular tachycardia episodes （100.0%） and 36 ventricular fibrillation episodes （87.8%）. The home monitoring group showed a higher appropriate detection rate of ventricular tachycardia （P 〈0.01） and ventricular fibrillation （P=0.02）. The proportion of inappropriate shock was comparable in the two groups （6/11 in the non-home monitoring group vs. 1/7 in the home monitoring group; m=0.08）. Conclusions The home monitoring ICD was able to provide information relating to inappropriate detection and shock earlier than conventional devices. It proved to be a reliable tool and has a strong potential to provide greater reaction time in the case of inappropriate shock.

Digoxin for Fetal Tachyarrhythmia:Toxicity in an Underweight Mother

To editor:The use of digoxin for the transplacental treatment of sustained fetal tachyarrhythmia(FT)was first reported in 1980.1 This medication is the first-line and most common antiarrhythmic in nonhydropic fetuses.Digoxin is administered to usually healthy mothers.Due to the intermediate solubility and low molecular weight of this drug,digoxin is readily delivered to the fetus via the placenta.The reported feto-maternal digoxin concentration ratio is 0.6–0.9 in normal pregnancies and lower in cases of hydrops fetalis(0.1–0.4)due to impaired transplacental transfer.2,3 Despite the long history of safe use in pregnancy,6%to 78%of patients have experienced digoxin side effects.4,5 Therefore,the maternal serum concentration of digoxin must be monitored to ensure drug safety and efficacy.Below is a case of FT treated using standard doses of digoxin and flecainide as adjunctive treatment.The patient experienced symptoms of digoxin toxicity,requiring dosage reduction.The patient gave her consent for the case to be reported.