Malignant Ventricular Dysrhythmias Research Articles

Electrophysiologic study for risk stratification in Brugada Syndrome: does it still matters?

Abstract Background The value of eletrophisiologic study (EPS) with programmed ventricular stimulation for risk stratification in patients with Brugada Syndrome (BS) remains controversial. Purpose The aim of this study is to determine the clinical and electrocardiographic predictors of positive EPS and to evaluate whether the induction of malignant ventricular dysrhythmias in the EPS is a predictor of events Methods A retrospective study was carried out of patients with spontaneous type 1 Brugada pattern followed up in Arrhythmology consultation at our Hospital. From this population, patients who underwent EPS for stratification of dysrhythmic risk were selected. Clinical and electrocardiographic variables were analyzed. Hospital records and monitoring data from cardiac devices were consulted. Statistical analysis was performed using SPSS 20.0. Results Fourty nine patients were included, with a mean age at the beginning of follow-up of 45±14 years, 40 (82%) of whom were male. In 16 individuals (33%) the EPS was positive with induction of malignant ventricular dysrhythmias. All patients with positive EPS implanted an implantable cardioverter-defibrillator and of the 32 patients with negative EPS, 10 implanted an implantable event recorder. The group of patients with positive EPS had a higher proportion of male patients (88% vs 78%). The median follow-up time was 31 months. The family history of sudden death, family history of BS, or identification of a genetic variant classified as pathogenic or probably pathogenic did not present any relationship with EPS positivity. Of the analyzed electrocardiographic markers, PR interval (178±29 vs 171±27) and QRS duration (119±24 vs 113±15) tended to be longer in patients with positive EPS. Additionally, it was found that 74% of patients with a QRS of less than 120 ms had a negative EPS. In the analysis of the value of EPS in the stratification of dysrhythmic risk, it was found that of all the patients who suffered events (4), 75% had positive EPS. Of the patients with negative EPS, only 3% (1) presented events in the follow-up. However, there was no significant association between these variables. Conclusion In this population, the analysed clinical elements did not correlate with the EPS result. Although there was no statistical significance, there was a tendency for patients with narrower QRS to be more likely to have negative EPS. Accordingly with published data, it was found that the EPS result was not a predictor of events during the follow-up period, which highlights the difficulty of risk stratification in patients with BS. Funding Acknowledgement Type of funding sources: None.

QT interval prolongation and the risk of malignant ventricular dysrhythmia and/or cardiac arrest: Systematic search and narrative review of risk related to the magnitude of QT interval length.

Prolongation of the QTc interval is associated with an increased risk of malignant ventricular dysrhythmias, such as ventricular tachycardia (VT), and sudden cardiac death. The quantifiable risk rates of adverse dysrhythmic outcome in relation to specific QTc interval length are not known. We conducted a literature review on the topic of QT interval prolongation in adult patients and the associated risk of malignant dysrhythmic event. We specifically formulated our literature search and subsequent literature review to address the following question: Can the clinician identify specific QTc intervals at which a specific quantifiable risk of malignant dysrhythmic event (malignant ventricular dysrhythmia and/or cardiac arrest) occurs in an undifferentiated adult patient population? In the literature search, we identified 701 studies; upon review using specific, pre-determined inclusion criteria, we identified 16 articles for inclusion in the review. From this literature, we were unable to answer the question in a quantifiable manner and only noted that the risk of malignant dysrhythmic event increases with progressively longer QTc interval. The current literature on this topic is inadequate to answer this important question due to heterogenous study methodology, patient populations, endpoints, and periods of observation. Additional prospective research is required on this topic, aimed at addressing the important issue of specific, quantifiable risk and its relation to degree of prolongation of the QTc interval.

QT interval prolongation and the rate of malignant ventricular dysrhythmia and cardiac arrest in adult poisoned patients.

Prolongation of QTc interval, a common electrocardiographic (ECG) abnormality encountered in the toxicology patient, is reportedly associated with an increased risk of malignant ventricular dysrhythmias (MVD), such as ventricular tachycardia (VT, with and without a pulse), ventricular fibrillation (VF), and/or cardiac arrest. Quantifiable cardiac arrest risk in relation to specific QTc interval length is not known in this population. We conducted a retrospective, observational study to assess the rate of cardiac arrest and its association with degree of QTc prolongation in a cohort of patients requiring toxicology consultation. 550 patients were included in our analysis (average age 36 years and 49% male). Average QTc was 453 milliseconds (ms). Overall incidence of cardiac arrest in the study cohort was 1.1% with 6 reported cases; when considering patients with QTc > 500 ms, incidence was 1.7%. Two patients with cardiac arrest experienced ventricular dysrhythmia with decompensation prior to cardiac arrest; four patients developed sudden cardiac arrest. The risk of malignant ventricular dysrhythmia, including cardiac arrest, is low in this poisoned patient population with an overall rate of 1.1%. Two-thirds of cardiac arrest cases occurred in patients with normal QTc intervals. When considering patients with prolonged QTc intervals, the rate of cardiac arrest remains very low at 0.8%. Considering QTc greater than 500 ms, the rate of cardiac arrest is 1.7%. Further prospective studies are required to quantify the risk of malignant ventricular dysrhythmias, including cardiac arrest, and its relation to the degree of QTc interval in poisoned patients.

Skin injury following prolonged fluoroscopy: early and late appearances

In October 2005, a 45-year-old woman presented to our centre for evaluation of recurrence of palpitations following a cardiac electrophysiology study performed 7 weeks previously at another centre. The patient had a long history of a hypercoagulable disorder (anti-phospholipid syndrome). At age 40, she had suffered an extensive inferolateral wall myocardial infarction. Coronary angiography demonstrated an occluded large marginal branch of the circumflex artery. This was treated by balloon angioplasty and stent placement. Unfortunately, despite optimal medical therapy, the patient developed progressive left ventricular systolic dysfunction. Indeed, by 4 years after her myocardial infarction, her left ventricular ejection fraction had fallen to 25%. Given the considerable potential for the development of malignant ventricular cardiac dysrhythmias associated with such depressed cardiac function,1 she then underwent prophylactic placement of an implantable cardioverter-defibrillator (ICD) device. She also underwent repeat coronary angiography at this time. This showed continuing patency of the previously placed stent and no other significant stenosis. One year later, the patient experienced multiple ICD shocks. Analysis of the device revealed that the ICD discharges had been caused by episodes of supraventricular tachycardia that had been mistakenly interpreted by the device as episodes of ventricular tachycardia. To address the problem of these inappropriate ICD discharges, the patient underwent a cardiac …

Sudden killer

Sudden killer

Anomalous origin of the left coronary artery from the pulmonary artery in an elderly patient, football player in youth

Anomalous origin of the left coronary artery from the pulmonary artery is a rare congenital defect. Without surgical treatment, approximately 90% of infants die within the first year of life. Late presentation in the adult or elderly is rare. Factors that may lead to survival in advanced age include the development of intercoronary collaterals. Furthermore, the risk of sudden cardiac death due to ischaemic malignant ventricular dysrhythmias exists even in asymptomatic adult patients and, classically, is precipitated by exercise. We report the case of a 67-year-old man, a football player in his youth, always asymptomatic until presentation at our centre for symptomatic sustained ventricular tachycardia and shortness of breath on exertion. We show the features of the ECG, transthoracic echocardiography, angiography study of the coronary and the pulmonary system, myocardial basal and stress gated single photon emission computed tomography with Tc-tetrofosmin and cardiac CT 64 slices. The patient was referred to cardiac surgery. We believe that this patient's favourable course may be ascribed to the large network of collaterals from the right coronary artery supplying the entire heart. However, the exact reason why these favourable evolutions (both vascular and clinical) occur only in some individuals remains largely unknown.

Electrocardiographic Findings of Acute Organophosphate Poisoning

In this study, we evaluated 85 patients who presented to our Emergency Department with organophosphate (OP) poisoning and discuss their associated electrocardiographic (ECG) abnormalities. Over a period of 3 years, 85 patients with OP poisoning were included in this retrospective study. ECG analysis included the rate, rhythm, ST-T abnormalities, conduction defects, and measurement of PR and QT intervals. The mean age was 32.2 ± 14.9 years. Sixty percent of the patients were female. The mean corrected QT interval (QTc interval) was 0.435 ± 0.052 s. Prolongation of the QTc interval (55.5%) was the most common ECG abnormality, followed by sinus tachycardia (31.8%). Elevation of the ST segment and low amplitude T waves were seen in 15 cases (17.6%). Patients with OP poisoning might reveal ECG abnormalities such as QTc interval prolongation or non-specific ST-T changes. QTc interval prolongation cannot be used as a unique predictive factor in determining short-term prognosis in OP poisoning. We found no clear relation between OP poisoning-related malignant ventricular dysrhythmia and QTc interval.

Prophylactic magnesium sulphate vs. lidocaine during off-pump coronary artery bypass grafting

Prophylactic magnesium sulphate vs. lidocaine during off-pump coronary artery bypass grafting

Droperidol: should the black box be light gray?

In December 2001, the United States Food and Drug Administration (FDA) added a “black box” warning to the labeling for droperidol stating that all doses, even those typically used for postoperative nausea and vomiting, were potentially associated with malignant ventricular dysrhythmias, including torsade de pointes. The 19 cases in which droperidol doses less than 10 mg were allegedly associated with such dysrhythmias are reviewed in detail. Confounding issues present in a majority of the cases make it difficult to incriminate droperidol as the likely cause of the reported adverse events.

Effects of cisapride on ventricular repolarization in children

Life-threatening ventricular dysrhythmias mainly attributed to QTc prolongation have been reported in adults and children who were using cisapride, a prokinetic agent that facilitates gastrointestinal motility. Recent adult and paediatric case reports have suggested an association of malignant ventricular dysrhythmias with administration of cisapride in conjunction with drugs that inhibit its cytochrome P-450 metabolism. Therefore, to analyse the time- and dose-related effects of cisapride on ventricular repolarization, we prospectively studied infants and children receiving cisapride with no concomitant medications. Standard 12-lead resting ECGs were obtained from 38 patients (mean age: 6.6 +/- 4.4 y) before the first dose of cisapride (0.8-1.2 mg/kg/d) therapy, and 3 d, 7 d and 1 mo after the first dose of continuing cisapride therapy. The corrected QT interval (QTc), dispersion of QT and QTc (QTD, QTcD) were calculated. Patients were divided into two groups according to dose of cisapride: Group 1 (n = 22) (0.8 mg/kg/d), Group 2 (n = 16) (1.2 mg/ kg/d). Data obtained from these patients were compared with a control group consisting of 372 normal children. No clinical adverse effects such as palpitations, presyncope or syncope were noted during the study. Baseline QTc, QTD and QTcD measurements of the study group were not different from those of the control group. Mean QTc values of the study group on days 7 and 30 of cisapride therapy were found to be significantly higher than those of the control group (p < 0.001 and <0.0001, respectively). Mean QTc values of the study group on days 7 and 30 of therapy were also significantly higher than those of baseline value (p < 0.01 and <0.001, respectively). Mean QTD and mean QTcD values that were recorded throughout the cisapride treatment in the study group were not found to be different from the baseline values and the values of the controls. Mean QTD and QTcD were also not found to be different between Groups 1 and 2. However, mean QTc was found to be more significantly increased from baseline at the first month of therapy in Group 2 (p < 0.05). The results of this study suggest that cisapride treatment cause prolongation of ventricular repolarization without causing increased heterogeneity of repolarization (QT dispersion). However, the clinical significance of this effect is unclear, because all the patients in this study group remained asymptomatic, without signs of dysrhythmia.

Patients with implantable cardioverter-defibrillators and their conceptions of the life situation: a qualitative analysis.

The implantable cardioverter-defibrillator (ICD) is today widely used for the treatment of sudden cardiac near-death episodes as a result of malignant ventricular dysrhythmia. After examining the literature, only four descriptive studies, all carried out in the USA, with a qualitative analysis based on ICD-patients' own perspectives on their life situation have been found. The aim of this study was to describe how patients living with an ICD-device in south-western Sweden conceive their life situation. As the focus was on patients' conceptions seen from a holistic perspective, an analysis inspired by phenomenography was employed on a strategic sample of 15 ICD-patients. Six categories emerged: a feeling of safety, a feeling of gratitude, a feeling of being, having a network, having a belief in the future, and gaining awareness. Although the findings cannot be generalized because of the descriptive research design, they illuminate the beneficial as well as intrusive effects of such a device, and emphasize the need for support groups for patients and families as well as further education for personnel in hospital and primary health care.

Complete AV-Block in Childhood: etiology, clinical course and therapy

Complete atrioventricular block (AVB) is a rare dysrhythmia in childhood, the etiology of which can be attributed to a number of causes. The aim of this study was to monitor the different causes, the clinical courses, and the indications for pacemaker therapy. Methods: In a retrospective analysis case histories, ECGs and Holter-ECGs from 71 patients with permanent AVB were reviewed. In addition, in selected cases cardiac catheterization and exercise testing were performed. Results: 37% had a congenital, and 48% an acquired AVB; in 15% of the cases the age of onset could not be determined. Among the neonates 31% each could be attributed to a congenital heart defect (CHD) or a maternal collagenosis; in 38% the reason could not be determined. The acquired AVB was most commonly the result of cardiac surgery. Other reasons were CHD without surgery (18%), myocarditis (15%), heart catheterization (6%) or cardiomyopathy (3%). 48% of patients required the implantation of a pacemaker (PM). The frequency of this operation depended on the cause of the AVB. It was, for instance, 100% in patients after cardiac surgery and 46% in patients with congenital AVB. Six patients had a long QTc interval, not one a malignant ventricular dysrhythmia. However, in the Holter-ECGs and during exercise testing, approximately 30% of the patients had ventricular extra beats. On the whole, the mortality was 19%; notably, these were all patients with CHD. Conclusion: The majority of pediatric AVB is either congenital or a complication of cardiac surgery. The necessity of PM implantation depends on the etiology of the AVB. Relevant ventricular dysrhythmias are rare in childhood; however, the physical capacity of the patients in the absence of CHD remains slightly reduced. The mid-term prognosis of patients with AVB without structural heart disease is good.

Malignant ventricular dysrhythmias in a patient with isovaleric acidemia receiving general and local anesthesia for suction lipectomy

We report the occurrence of severe ventricular arrhythmias in a patient with isovaleric acidemia during general anesthesia for suction lipectomy. The timing of events and character of the ECG changes are most consistent with bupivacaine toxicity after subcutaneous injection of tumescence solution containing this local anesthetic. The patient had previously documented carnitine deficiency, a condition which, we speculate, may lower the threshold for bupivacaine induced cardiotoxicity. We review clinical considerations in isovaleric acidemia and conclude that the use of bupivacaine in these patients probably should be avoided.

Restenosis presented with unstable angina and myocardial infarction: One explanation for late cardiac events following directional coronary atherectomy

Three cases of restenosis after directional coronary atherectomy (DCA) presented with unstable angina and then myocardial infarction. Two of them were complicated with malignant ventricular dysrhythmia. A total or subtotal thrombotic occlusion at the DCA site was shown. This fulminating course of restenosis could partially explain the higher late cardiac morbidity and mortality after DCA than after percutaneous transluminal balloon angioplasty.

Free and total lidocaine levels in cardiac surgical patients

A lidocaine bolus of 2 mg/kg has been shown to decrease the incidence of ventricular fibrillation in cardiac surgical patients during reperfusion following aortic cross-clamp release (CCR). In an effort to extend this effect into the immediate postoperative period, many centers routinely administer a prophylactic lidocaine infusion for the first 12 to 24 hours after surgery. Sequential total serum lidocaine levels were measured over 6 hours in 28 adult cardiac surgical patients without liver, kidney, or respiratory disease, and free serum lidocaine levels were measured in 15 of these patients. In addition, pharmacokinetic data were collected and analyzed in 8 of these patients. Each patient received a lidocaine bolus of 1.5 mg/kg and an infusion at 2 mg/min immediately before CCR. Serum levels were determined just before CCR, and at 10, 20, 30, 60, 120, 240, and 480 minutes after CCR. More than 50% of patients had subtherapeutic total serum lidocaine levels from 20 to 120 minutes after CCR, but free lidocaine levels remained within the therapeutic range. No patient showed malignant ventricular dysrhythmias during the study. The results suggest that (1) it may be misleading to estimate free lidocaine concentration based on total lidocaine levels; and (2) free drug is the moiety-responsible for lidocaine's antiarrhythmic effect.

Antitachycardia pacing with cardioverter-defibrillator backup for malignant ventricular dysrhythmias

This article provides a summary of the history of antitachydysrhythmic devices and their current application in patients with ventricular dysrhythmias. Future trends are also discussed, followed by a case study illustrating the nursing care required for a patient with a combination antitachycardia pacemaker and automatic implantable cardioverter-defibrillator for slow ventricular tachycardia. The basic principles provided can be incorporated into the teaching plans of patients with antidysrhythmic devices for malignant ventricular dysrhythmias.

Improved survival from cardiac arrest with open chest massage

Improved survival from cardiac arrest with open chest massage

Lysophosphatidyl choline potentiates Ca2+ accumulation in rat cardiac myocytes.

Lysophosphoglycerides are amphiphilic phospholipids that accumulate in ischemic myocardium and elicit electrophysiological alterations in normoxic Purkinje fibers and ventricular muscle that are analogous to alterations characteristic of ischemic tissue in vivo and that are compatible with altered sarcolemmal permeability to divalent cations. To assess directly the potential influence of lysophosphoglycerides on calcium transport, we characterized changes in the accumulation of 45Ca2+ by cultured cardiac myocytes exposed to selected concentrations of lysophosphatidyl choline (LPC). Perfusion for 10 min with 80 microM LPC augmented the amount of 45Ca2+ in myocytes compared with that in control cells (5.1 +/- 0.7 vs. 2.8 +/- 0.26 nmols Ca2+/mg protein, respectively; P less than 0.005) but did not alter total cell calcium content measured by atomic absorption spectrometry (11.6 +/- 1.0 nmols/mg protein), suggesting equivalent augmentation of bidirectional Ca2+ flux by LPC. In contrast, perfusion for 15 min with 100 microM LPC not only augmented 45Ca2+ accumulation but also increased total cellular Ca2+ content, as the quantity of 45Ca2+ accumulated reached 16.9 +/- 1.4 nmols/mg protein, a value substantially exceeding the normal total Ca2+ content (P less than 0.0025 compared with control cells). In contrast to results observed after only a 5-min exposure to 100 microM LPC, Ca2+ accumulation induced by 15 min of perfusion was not precluded by verapamil (10(-8)M), could not be reversed by perfusion without LPC, and was associated with complete cessation of beating, markedly altered morphology, and substantial depletion of cellular creatine kinase activity. Thus LPC may not only contribute to malignant ventricular dysrhythmias but also may potentiate ischemic injury by facilitating calcium ingress.

Influences of labetalol a combined alpha- and beta-adrenergic blocking agent on the dysrhythmias induced by coronary occlusion and reperfusion.

We have previously demonstrated a significant antifibrillatory effect of α-adrenergic blockade during myocardial ischaemia and reperfusion, enhanced α-adrenergic responsivity and increased α1-adrenergic receptors in ischaemic myocardium. β-adrenergic blockade is also antiarrhythmic in ischaemic hearts and may decrease the ultimate area of necrotic tissue after infarction. The present study was performed to assess the relative β- and α-adrenergic blocking potency of labetalol in the chloralose anaesthetised cat and correlate this to its antiarrhythmic efficacy during LAD coronary occlusion for 35 min followed by reperfusion. Based on the dose ratio10 (DR10) for isoprenaline-induced tachycardia (β) and phenylephrine-induced increase in mean systemic arterial pressure (α), labetalol was 3.1 times less potent than d,l-propranolol (β) and 6.5 times less potent than phentolamine (α). Labetalol was found to be 11.5 times more potent as a β-adrenergic blocking agent than as an α-adrenergic blocking agent. Labetalol (1 mg·kg−1) failed significantly to reduce either the number of premature ventricular complexes (PVCs) or incidence of ventricular fibrillation (VF) during occlusion (827± 150 to 852±246 PVCs and 31% to 20% VF) or reperfusion. In contrast, labetalol at 2 mg·kg−1 and 5 mg·kg−1 significantly (P<0.05) reduced the number of PVCs during occlusion (320±94 and 466± 137, respectively) as well as the incidence of VF (9% and 7%, respectively). During, reperfusion, labetalol (5 mg·kg−1) failed to reduce the number of PVCs but abolished mortality due to VF. The antifibrillatory effect of labetalol was not due to alterations in systemic arterial pressure, heart rate, LVEDP, cardiac output, stroke work or total peripheral resistance. Thus, labetalol, an agent well-tolerated clinically, induces profound antiarrhythmic effectiveness during both experimental myocardial ischaemia and reperfusion and may prove to be an effective agent in the prevention and treatment of malignant ventricular dysrhythmia associated with acute myocardial infarction in man.

The role of biochemical factors in ventricular dysrhythmia accompanying ischemia.

Early malignant ventricular dysrhythmia induced by ischemia appear to depend on electrophysiological changes predisposing toward reentry. These changes are not readily explicable in terms of direct responses to hypoxia alone. Data from several laboratories make it increasingly clear that regional, heterogenous accumulations of noxious ions and metabolites play an important role. In addition to previously recognized factors including potassium, lactate, and hydrogen ion, both free and esterified fatty acid derivatives and metabolites of membrane phospholipids, particularly lysophosphoglycerides, have been implicated as potential mediators. Elucidation of the biochemical mechanisms responsible is of particular importance to development of prophylactic and therapeutic interventions with the needed specificity to be effective in reducing the incidence and severity of malignant ventricular dysrhythmia induced by ischemia and hence of sudden death.