Ventricular Tachycardia

REEK, S., ET AL.: Inducibility of Sustained Ventricular Tachycardia in a Closed-Chest Ovine Model of Myocardial Infarction. Tbe two goals of this study were (1) to develop a closed-chest animal model of monomorphic ventricular tachycardia; and (2) to investigate the effect of dual site pacing on inducibility of ventricular tachycardia. In the first part ofthe study, 10 of 14 sheep underwent successful induction of myocardial infarction by temporary balloon occlusion of the left anterior descending coronary artery. After a foUow-up period of 21-43 days, sustained monomorphic ventricular tachycardia could be induced during programnwd electrical stimulation usinga "clinical" stimulation protocol in dofthe lOsheep. The number of ventricular tachycardia episodes per animal varied between 5 and 70. Ventricular fibrillation was never induced during programmed electrical stimulation. Ventricular tachycardia episodes lasted from 30 seconds up to 15 minutes and were terminated by antitachycardia pacing or DC cardioversion. In the second part ofthe study, the effect of dual site stimulation on ventricular tachycardia inducibility was investigated. High current stimuli from an area within the infarcted zone were given with the Si programmed stimulation protocol. This dual site stimulation showed no effect on ventricular tachycardia induction during programmed electrical stimulation. This animal model shows a high induction rate of sustained monomorphic ventricular tachycardia in the chronic phase of myocardial infarction. The high incidence of ventricular tachycardia inducibility provides a reliable tool to study new techniques for the prevention of ventricular tachyarrhythmias.

Introduction: The treatment and outcome of acute myocardial infarction (AMI) has evolved greatly over the past few decades. We compared the mortality and complication rates of patients with AMI admitted to the Coronary Care Unit (CCU) in 2002 to previously reported data. Materials and Methods: All data for AMI patients admitted to National Heart Centre CCU in 2002 were collected through the Singapore Cardiac Data Bank, including demographics, inhospital complications and mortality. These were compared to previous reports from the same institution in 1988, 1975 and 1967. Results: A total of 516 cases with AMI were identified. A higher proportion of patients were aged ≥ ≥ ≥ ≥ ≥70 years in 2002 (31.8%) compared to 1988 (25%), 1975 (11%) and 1967 (5.6%). Acute percutaneous transluminal coronary angioplasty (PTCA) was performed in 250 of 516 (48%) patients in 2002. The overall in-patient and age-standardised mortality was 14.7% and 10% respectively, compared to 20.6% and 17% respectively in 1988 (P = 0.06). For the 250 patients who underwent acute PTCA, overall mortality was 5.2% compared to 24% in those who did not (P <0.001). Common in-hospital complications included heart failure (38%), non-sustained ventricular tachycardia (8%), atrial fibrillation (8%) and complete heart block (6%). Age, heart failure, bundle branch block and sustained ventricular tachycardia were associated with higher mortality by univariate analysis. On multivariate analysis, older age, heart failure and the absence of percutaneous intervention were independently associated with higher mortality. Conclusion: In-hospital mortality for AMI patients admitted to the CCU declined from 1988 to 2002 despite a higher proportion of elderly patients.

Introduction Our aim was to study the outcomes and predictors of in-hospital cardiopulmonary resuscitation (CPR) among adult patients at a tertiary care centre in Pakistan. Methods We conducted a retrospective chart review of all adult patients (age ≥14 years), who underwent CPR following cardiac arrest, in a tertiary care hospital during a 5-year study period (June 1998 to June 2003). We excluded patients aged 14 years or less, those who were declared dead on arrival and patients with a "do not resuscitate" order. The 1-and 6-month follow-ups of discharged patients were also recorded. Results We found 383 cases of adult in-hospital cardiac arrest that underwent CPR. Pulseless electrical activity was the most common initial rhythm (50%), followed by asystole (30%) and ventricular tachycardia/fibrillation (19%). Return of spontaneous circulation was achieved in 72% of patients with 42% surviving more than 24 h, and 19% survived to discharge from hospital. On follow-up, 14% and 12% were found to be alive at 1 and 6 months, respectively. Multivariable logistic regression identified three independent predictors of better outcome (survival >24 h): non-intubated status [adjusted odds ratio (aOR):3.1, 95% confidence interval (CI):1.6-6.0], location of cardiac arrest in emergency department (aOR: 18.9, 95% CI:7.0-51.0) and shorter duration of CPR (aOR:3.3, 95% CI:1.9-5.5). Conclusion Outcome of CPR following in-hospital cardiac arrest in our setting is better than described in other series. Non-intubated status before arrest, cardiac arrest in the emergency department and shorter duration of CPR were independent predictors of good outcome.

The purpose of this article is to review the nerve sprouting hypothesis of sudden cardiac death. It is known that sympathetic stimulation is important in the generation of sudden cardiac death. For example, there is a diurnal variation of sudden death rate in patients with myocardial infarction. Beta blockers, or drugs with beta blocking effects, are known to prevent sudden cardiac death. It was unclear if the cardiac nerves in the heart play only a passive role in the mechanisms of sudden death. To determine if nerve sprouting and neural remodeling occur after myocardial infarction, we performed immunocytochemical studies of cardiac nerves in explanted native hearts of transplant recipients. We found that there was a positive correlation between nerve density and a clinical history of ventricular arrhythmia. Encouraged by these results, we performed a study in dogs to determine whether or not nerve growth factor (NGF) infusion to the left stellate ganglion can facilitate the development of ventricular tachycardia (VT), ventricular fibrillation (VF), and sudden cardiac death (SCD). The results showed that augmented myocardial sympathetic nerve sprouting through NGF infusion plus atrioventricular (AV) block and MI result in a 44% incidence (four of nine dogs) of SCD and a high incidence of VT in the chronic phase of MI. In contrast, none of the six dogs (with AV block and MI) without NGF infusion died suddenly or had frequent VT episodes. Based on these findings, we propose the nerve sprouting hypothesis of ventricular arrhythmia and SCD. The hypothesis states that MI results in nerve injury, followed by sympathetic nerve sprouting and regional (heterogeneous) myocardial hyperinnervation. The coupling between augmented sympathetic nerve sprouting with electrically remodeled myocardium results in VT, VF and SCD. Modification of nerve sprouting after MI may provide a novel opportunity for arrhythmia control.

successfully treated. A CT scan of the head revealed cerebral oedema. Whilst in the intensive care unit, he developed renal failure and rhabdomyolysis. The metabolic abnormalities seen at the time of admission normalised within 48 h with IV glucose infusion. Biological investigations, including urinary organic acids and plasma acylcarnitines, showed results compatible with MCAD deficiency. Mutation analysis revealed the patient was homozygous for the classical mutation A985G. This is one of only a few reports of severe cardiac arrhythmia in an adult due to MCAD deficiency. This condition is probably under-diagnosed in adult patients with acute neurological and/or cardiac presentations.

Resveratrol has been demonstrated to produce a variety of biological actions. Accumulating line of evidence supported the view that resveratrol may exert protective effect on the cardiovascular system. The aim of the study was to assess the antiarrhythmic profile as well as electrophysiological properties of resveratrol. We observe the antiarrhythmic effect of resveratrol on aconitine induced rat arrhythmia, ouabain induced guinea pig arrhythmia, and coronary ligation induced rat arrhythmia animal models. Resveratrol significantly and dose-dependently increased the doses of aconitine and ouabain required to induce the arrhythmia indexes. In coronary ligation induced rat arrhythmia model, resveratrol shortened duration of arrhythmia, decreased incidence of ventricular tachycardia and mortality. Electrophysiological experiment revealed that resveratrol could shorten APD through inhibition of I Ca and selective enhancement of I Ks without an effect on I Kr .

Tricyclic antidepressant overdose is one of the most common causes of serious drug poisoning in children and adults. We report a 17-month-old girl with severe amitriptyline intoxication. She was admitted to hospital because of lethargy and seizures. It was estimated that she took approximately 75 mg/kg of amitriptyline 2 h before admission. On examination she was comatose, had ventricular tachycardia and multifocal clonic seizures. Intravenous fluid, per oral activated charcoal, diazepam, lidocaine, and sodium bicarbonate infusion were given. However, there was no response to this therapy, and the patient remained in a deep coma with cardiac arrhythmias and seizures. Hemoperfusion (HP) was performed for 2 h. During this procedure, cardioversion was used six times due to ventricular fibrillation. She had a very good clinical response to HP and no complication was observed. We suggest that HP may be an effective treatment in children with severe amitriptyline intoxication.

Background: Mitral annular disjunction (MAD) consists of an altered spatial relation between the left atrial wall, the attachment of the mitral leaflets, and the top of the left ventricular (LV) free wall, manifested as a wide separation between the atrial wall-mitral valve junction and the top of the LV free wall. Originally described in association with myxomatous mitral valve disease, this abnormality was recently revisited by a surgical group that pointed its relevance for mitral valve reparability. The aims of this study were to investigate the echocardiographic prevalence of mitral annular disjunction in patients with myxomatous mitral valve disease, and to characterize the clinical profile and echocardiographic features of these patients.

Although expression of numerous ion channels is altered in heart failure (HF), mechanisms by which dysfunction at the ionic and molecular levels lead to ventricular tachyarrhythmias in HF are unknown. Previously, we found that transmural heterogeneities of repolarization play a critical role in the genesis of polymorphic ventricular tachycardia (PVT) when QT interval was prolonged in LQT2. Because QT interval is also prolonged in HF, we hypothesized that transmural heterogeneities are a mechanism of PVT in HF. Optical action potentials were measured simultaneously from cells spanning the entire transmural wall of arterially perfused canine wedge preparations. Wedges were isolated from dogs without (control, nϭ5) and with HF (nϭ8) produced by rapid ventricular pacing. In HF, action potential duration (APD) prolongation was markedly heterogeneous across the transmural wall, and was characterized by disproportionate APD prolongation of midmyocardial (M) cells. APD prolongation of M cells accounted for QT-interval prolongation, and caused significant increases (PϽ0.01) in spatial gradients of repolarization across the ventricular wall from 4.3Ϯ2.1 (control) to 12.4Ϯ3.5 ms/mm (HF). Enhanced gradients were directly responsible for development of functional conduction block, leading to PVT in 63% of HF wedges but in no controls (PϽ0.03). Moreover, intramural decremental conduction and block of the premature impulse, preceded each episode of PVT, and always occurred at the border between M-cell and subepicardial zones, where repolarization gradients were highest. Selective prolongation of APD within M cells underlies several key features of the HF phenotype, including QT-interval prolongation, transmural heterogeneity of repolarization, and susceptibility to conduction block and reentrant PVT. (Circ Res. 2003;93:638-645.)

nization therapy (CRT) or biventricular pacing (BVP) is becoming an important treatment option in patients with severe congestive heart failure (CHF) and electrical dyssynchrony. When combined with implantable cardioverter-defibrillator (ICD) therapy, cardiac resynchronization therapy with a defibrillator (CRT-D) has been shown to improve quality of life, functional class, and, most recently, survival. However, left ventricular (LV) stimulation in the form of BVP in patients at high risk of developing ventricular tachyarrhythmias has raised concerns that BVP may be proarrhythmic. We describe the incidence, clinical characteristics, and management in a series of patients who developed ventricular tachycardia storm (VTS) after initiation of BVP.

Cardiovascular disease has the highest mortality rate globally which mean that more people die annually from it than from any other cause. The disease should be detected and anticipated as early as possible because of its fatality. For many years, electrocardiograph (ECG) has become the golden standard for cardiovascular disease detection. The main purpose of this research work is to develop ECG signal interpretation software on Android 2.2 platform. The methods consist of ECG data preparation, QRS detector, heart rate and QRS time extraction, and classification. The system classifies the abnormalities of heart rhythm into: Premature Ventricular Contraction (PVC) and Supra Ventricular Tachycardia (SVT). To manifest the performance of this software, data from MIT-BIH Arrhythmia Database were used. The overall accuracy of this software in determining heart rate is 97.10%. This software also has average N-Accuracy of 99.15%, average V-Accuracy of 84.22%, average SVT-Accuracy of 97.78%, and the overall classification accuracy of 93.71%.

Background. -Ajmaline challenge is commonly used for the diagnosis of Brugada syndrome. A slow infusion rate has been recommended in view of the proarrhythmic risk, but the diagnostic value of various infusion rates has not been investigated. Aims. -To compare rapid and slow ajmaline infusion rates and to assess the proarrhythmic risk.

The Short QT Syndrome is a recently described new genetic disorder, characterized by abnormally short QT interval, paroxysmal atrial fibrillation and life threatening ventricular arrhythmias. This autosomal dominant syndrome can afflict infants, children, or young adults; often a remarkable family background of cardiac sudden death is elucidated. At electrophysiological study, short atrial and ventricular refractory periods are found, with atrial

In this paper, we proposed an algorithm for arrhythmia classification, which is associated with the reduction of feature dimensions by linear discriminant analysis (LDA) and a support vector machine (SVM) based classifier. Seventeen original input features were extracted from preprocessed signals by wavelet transform, and attempts were then made to reduce these to 4 features, the linear combination of original features, by LDA. The performance of the SVM classifier with reduced features by LDA showed higher than with that by principal component analysis (PCA) and even with original features. For a cross-validation procedure, this SVM classifier was compared with Multilayer Perceptrons (MLP) and Fuzzy Inference System (FIS) classifiers. When all classifiers used the same reduced features, the overall performance of the SVM classifier was comprehensively superior to all others. Especially, the accuracy of discrimination of normal sinus rhythm (NSR), arterial premature contraction (APC), supraventricular tachycardia (SVT), premature ventricular contraction (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF) were 99.307%, 99.274%, 99.854%, 98.344%, 99.441% and 99.883%, respectively. And, even with smaller learning data, the SVM classifier offered better performance than the MLP classifier.

Long QT syndrome is a disease of delayed ventricular repolarization. It manifests clinically as recurrent syncope and sudden cardiac death caused by an atypical form of polymorphic ventricular tachycardia known as torsades de pointes (TdP). Evidence obtained from the studies using the rabbit left and right ventricular wedge preparations indicates that the development of TdP is relying not only on the genesis of an R-on-T trigger, but also on the formation of a functional reentrant substrate. When ventricular endocardial or subendocardial repolarization is prolonged either because of gene mutations or by drugs that reduce the net repolarization current, cell membrane potential fluctuates during phase 2 of the action potential phase 2 because of reactivation of L-type calcium current, that is, the appearance of phase 2 early afterdepolarization (EAD). In the rabbit left ventricular wedge, QT prolongation and EAD due to pure IKr inhibition are accompanied by a disproportional increase in transmural dispersion of repolarization (TDR). Early afterdepolarization in endocardium or subendocardium is able to produce new action potentials in cells with a relatively short action potential duration (eg, ventricular epicardium) probably via an electrotonic effect when TDR is large enough. This, in turn, results in an R-on-T extrasystole that is capable of initiating TdP. Enhanced TDR is essential not only for the genesis of the first initiating beat of TdP by facilitating the propagation of EAD, but also for the maintenance of TdP by serving as a functional reentrant substrate.

Patients with scar-related ventricular tachycardia (VT) are subject to frequent arrhythmia recurrences; antiarrhythmic drug therapy has been disappointing due to poor efficacy and side effects. Patients receiving multiple implantable cardioverter-defibrillator shocks because of VT have impaired quality of life. The role of catheter ablation in the treatment of ventricular arrhythmias has been increasing in the last 2 decades. As more knowledge is gained about the mechanisms of VT, the potential for doing ablation has increased. Now, multiple VTs and unstable VTs can be targeted by ablation strategies. Also, electroanatomic mapping systems have made substrate mapping feasible. The purpose of this article is to review the selection and preparation of patients who require catheter ablation for scar-related VT, the different mapping techniques, and the ablation strategies employed. An overview of the pathophysiology of scarrelated VT and the variety of heart diseases that are related to scar-related VT is provided. (Curr Probl Cardiol 2009;34: 225-270.)

Long QT and short QT syndromes (LQTS and SQTS) are cardiac repolarization abnormalities that are characterized by length perturbations of the QT interval as measured on electrocardiogram (ECG). Prolonged QT interval and a propensity for ventricular tachycardia of the torsades de pointes (TdP) type are characteristic of LQTS, while SQTS is characterized by shortened QT interval with tall peaked T-waves and a propensity for atrial fibrillation. Both syndromes represent a high risk for syncope and sudden death. LQTS exists as a congenital genetic disease (cLQTS) with more than 700 mutations described in 12 genes (LQT1-12), but can also be acquired (aLQTS). The genetic forms of LQTS include Romano-Ward syndrome (RWS), which is characterized by isolated LQTS and an autosomal dominant pattern of inheritance, and syndromes with LQTS in association with other conditions. The latter includes Jervell and Lange-Nielsen syndrome (JLNS), Andersen syndrome (AS), and Timothy syndrome (TS). The genetics are further complicated by the occurrence of double and triple heterozygotes in LQTS and a considerable number of nonpathogenic rare polymorphisms in the involved genes. SQTS is a very rare condition, caused by mutations in five genes (SQTS1-5). The present mutation update is a comprehensive description of all known LQTS-and SQTS-associated mutations.

Ms. C, a very active professional woman who enjoyed skiing, scuba diving and sky-diving, was diagnosed with a cardiac arrhythmia and mitral valve prolapse in 1989.By 1993, she was experiencing 700 extra heartbeats per hour and was told that she was at risk for sudden death. She was prescribed beta-blockers, Valium and aspirin, the side effects of which were stomach-aches,

Study objective: Studies indicate that ventricular tachycardia (VT) and ventricular fibrillation (VF) are no longer the most common rhythms initially documented in out-of-hospital sudden cardiac death. Although the outcome from asystole and rhythms designated as pulseless electrical activity (PEA) is reported as poor (approximately 1% survival), resuscitative efforts for these patients are still encouraged. The purpose of this study was to determine the potential contribution that this patient group makes to overall survivorship.

Idiopathic outflow tract ventricular tachycardia (VT) can arise from the right (RVOT) or left ventricular outflow tract (LVOT). The electrocardiographic (ECG) pattern of RVOT VT is typical in most patients, showing a monomorphic left bundle branch block (LBBB) QRS morphology with an inferior axis. Radiofrequency catheter ablation can be performed with a high success rate and provides a curative therapeutic approach. However, not all VTs with LBBB and inferior axis can be ablated from the RVOT. It has become apparent that

Outflow tract ventricular tachycardias (OT-VTs) re the most common form of idiopathic VTs. In > 80-90% of cases OT-VT originates from the right ventricular outflow tract, however, other origins like the septum, the left ventricular outflow tract, the pulmonary artery, the aortic sinus of Valsalva, the area near the His bundle, and the epicardial surface of the ventricles have been described. OT-VT is a diagnosis by exclusion, i.e., the possible concomitant structural heart disease should be adequately explored and ruled out in all patients presenting with OT-VT. Ablation should be recommended for all patients who present with syncope and who also remain symptomatic despite optimal medical therapy with a well-tolerated drug.

In up to 10% of patients who present with ventricular tachycardia (VT), obvious structural heart disease is not identified. In such patients, causes of ventricular arrhythmia include right ventricular outflow tract (RVOT) VT, extrasystoles, idiopathic left ventricular tachycardia (ILVT), idiopathic propranolol-sensitive VT (IPVT), catecholaminergic polymorphic VT (CPVT), Brugada syndrome, and long QT syndrome (LQTS). RVOT VT, ILVT, and IPVT are

The objective of this study was to examine the effects of Y-27632, a selective Rho-kinase inhibitor, on ischemic preconditioning (IP) and carbachol preconditioning (CP) in anesthetized rats. Administration of Y-27632 (0.1 mg/kg) produced slight, but not significant, reduction in mean arterial blood pressure and suppressed the total number of ventricular ectopic beats (VEBs). IP, induced by 5 min coronary artery occlusion and 5 min reperfusion, decreased the incidence of ventricular tachycardia (VT) from 100 (n = 30) to 25% (n = 24) and abolished the occurrence of ventricular fibrillation (VF) (40% in control group) during 30 min of ischemia. The incidences of VT and VF in Y-27632 + IP group were found to be similar to IP group. Carbachol (4 mg/kg/min for 5 min) induced marked depressions in mean arterial blood pressure, heart rate and attenuated the total number of VEBs, but significant reductions in VT and VF incidences were noted in Y-27632 + CP group. Y-27632 infusion for 5 min abolished VF occurrence. Marked reductions in plasma lactate levels were observed in all treatment and preconditioning groups. IP led to marked decrease in malondialdehyde levels. Decreases in infarct size were also observed with all groups when compared to control. These results suggest that infusion of Y-27632 was able to produce cardioprotective effects on myocardium against arrhythmias, infarct size or biochemical parameters and mimic the effects of ischemic preconditioning in anesthetized rats. Therefore, it is likely that inhibition of Rho-kinase is involved in the signaling cascade of myocardial preconditioning. #

Les antiarythmiques ont une efficacité et des effets secondaires qui varient selon les molécules et la classe pharmacologique à laquelle ils appartiennent. Leur utilisation en médecine d'urgence préhospitalière et hospitalière repose sur des règles précises, et ce d'autant plus que leur marge thérapeutique est étroite. Parmi ces règles, les principales sont l'appréciation rapide du retentissement hémodynamique, l'identification précise du trouble du rythme, la recherche du facteur déclenchant et/ou favorisant, la connaissance de la pharmacocinétique de la molécule utilisée et le respect de leurs associations. Parmi les molécules injectables, l'adénosine triphosphate (Striadyne ® ) garde une place de choix dans le traitement des tachycardies jonctionnelles, le sotalol et l'amiodarone dans le traitement des tachycardies ventriculaires (en respectant rigoureusement les précautions d'injections). Les associations d'antiarythmiques sont à proscrire dans l'urgence. La cardioversion par choc électrique externe est réservée aux états de choc et/ou aux échecs du traitement médicamenteux. Le respect des règles de prescription permet, dans une situation précaire aux urgences ou en préhospitalier, de passer un cap avant de confier le patient au cardiologue pour la suite de l'exploration et du traitement de fond de ce trouble du rythme. © 2005 Société de réanimation de langue française. Publié par Elsevier SAS. Tous droits réservés.

Objective: To determine whether carbamazepine monotherapy in epilepsy patients is or is not associated
with prolongation of the QTc interval.
Methods: This case-control study enrolled 100 consecutive
patients with generalized tonic-clonic seizures. Fifty patients were already taking carbamazepine for a variable time, and the rest (n=50) were not on any antiepileptic drug. The QTc interval was calculated after doing a resting 12-lead ECG examination on a single occasion.
Results: Of the 50 patients who had received arbamazepine, 11 patients displayed prolongation of their QTc interval, while 8 patients out of the 50 in the control group had QTc interval prolongation after correction for gender; p-value
=0.49, OR 1.36, 95% CI 0.54-3.29.
Conclusion: This study demonstrated no statistically significant association between carbamazepine monotherapy and prolongation of the QTc interval. Carbamazepine does not seem to prolong the QT
interval when used as monotherapy for epilepsy. The presence of prolonged QTc interval in such patients should prompt a search for co-factors that prolong this interval, such as multiple medications, electrolytes disturbances, structural heart disease, and congenital long QT interval syndromes.

To evaluate the influence of local tissue refractorl-extrastimuli became flat plus increasing with double ness and delay In intervening tissue on the ability of ventricular extrastimuli. All other patterns were unsingle ventricular extrastimuli to reset and characchanged. In the 19 VTs reset by both single and terize a resetting response pattern In ventricular double ventricular extrastimuli, the estimate of both tachycardia (VT), single ventricular extrastimuli the total reset zone (94 f 36 vs 56 f 32 ms) and were delivered during 81 VTs and double ventricular the flat portion of the reset zone (52 f 42 vs 42 f extrastimuli in 45 of the 81 VTs. Resetting of VT 28 ms) was significantly longer with double ventricwas recognized as a less than fully compensatory ular extrastimuli (p <O.OOl and p <0.02, respecpause after stimulation and was seen in 43 of 81 tively). In conclusion: (1) when single ventricular Ws (53 % ) with single ventricular extrastimuli and extrastimuli failed to reset a VT, double ventricular 35 of 45 (78 % ) with double ventricular extrastimu-extrastimuli from the same site may reset the VT, Ii. Double ventricular extrastimuli reset 16 VTs not

Analogous to the use of circular loop catheters to guide ablation around the pulmonary veins, it may be advantageous to use a multipolar catheter in the ventricle for rapid mapping and to guide ablation. We describe a technique using double access into the left ventricle for multipolar electroanatomic mapping and ablation of scar-mediated ventricular tachycardia (VT).

We have proposed the notion of short-time multifractality and used it to develop a novel approach for arrhythmia detection. Cardiac rhythms are characterized by short-time generalized dimensions (STGDs), and different kinds of arrhythmias are discriminated using a neural network. To advance the accuracy of classification, a new fuzzy Kohonen network, which overcomes the shortcomings of the classical algorithm, is presented. In our paper, the potential of our method for clinical uses and real-time detection was examined using 180 electrocardiogram records [60 atrial fibrillation, 60 ventricular fibrillation, and 60 ventricular tachycardia]. The proposed algorithm has achieved high accuracy (more than 97%) and is computationally fast in detection.

Hypothesis Endocardial catheter ablation of ventricular tachycardia (VT) may fail if originating from epicardial or intramural locations. We hypothesized that mapping could be achieved using an angioplasty guidewire in the coronary circulation, to guide trans-coronary ablation. Methods and results Six patients (2 male), 64±14 years and previously unsuccessful endocardial VT ablation were studied. Using ECG and existing endocardial mapping data, a coronary artery supplying the predicted VT origin was selected. A 0.014-in angioplasty guidewire was advanced into branches of the artery and connected to an amplifier to record unipolar signals against an indifferent electrode within the inferior vena cava. An uninflated angioplasty balloon was advanced over the wire such that only the distal 5 mm was used for mapping. One VT per patient was mapped (CL 348± 102.1 ms). Diastolic potentials were recorded from all (77.7± 43.8 ms pre-QRS onset) and concealed entrainment demonstrated in 3. Pacemapping during sinus rhythm was used in the remainder due to failure of entrainment (n=2) or degeneration to VF (n=1). Following branch identification, cold saline injection causing VT termination was used for further confirmation. Five VTs were ablated using intra-coronary ethanol injection via the central lumen of the inflated over the wire balloon. The other was ablated using radiofrequency energy in a coronary vein adjacent to the target artery, which was too small for an angioplasty balloon. No complications or recurrence of ablated VT was seen over 19±17 months of follow up. Conclusions Intracoronary guidewire mapping is a novel method of electrophysiological epicardial mapping to help guide trans-coronary VT ablation.

The lateral decubitus and beach-chair positions each offer unique benefits to the shoulder surgeon with respect to visualization, efficiency, and ease during arthroscopic shoulder procedures. The purpose of this article was to comprehensively review the reports and studies documenting independent and dependent complications related to patient positioning and anesthesia during arthroscopic shoulder surgery. The lateral decubitus position has been associated with the potential for peripheral neurapraxia, brachial plexopathy, direct nerve injury, and airway compromise. The beach-chair position has been associated with cervical neurapraxia, pneumothorax, and the potential for end-organ hypoperfusion injuries (when deliberate hypotension is used). Potentially concerning are hypotensive bradycardic events, which may be relatively common in association with the use of epinephrine-containing interscalene anesthetics in beach chair-positioned patients. Irrigant complications (fluid spread, ventricular tachycardia) are avoidable risks not unique to either specific position. Although minor transient anesthetic-and position-related complications (neurapraxia, hypotension) may occur in as many 10% to 30% of patients, major complications such as end-organ damage or permanent impairments are exceedingly rare. Regardless of position, complications are almost uniformly avoidable if surgeon and anesthetist exercise care and prudent attention to position and anesthetic choices. The purpose of this article is to review the potential for position-and anesthesia-related complications and acquaint the shoulder surgeon with the proposed pathophysiologic mechanisms that can lead to them.

We aimed to evaluate the safety and long-term efficacy of the magnetic navigation system (MNS) in a large number of patients. The MNS has the potential for improving safety and efficacy based on atraumatic catheter design and superior navigation capabilities.

Cardiac arrhythmias such as ventricular tachycardia (VT) or ventricular fibrillation (VF) are the leading cause of death in the industrialised world. There is a growing consensus that these arrhythmias arise because of the formation of spiral waves of electrical activation in cardiac tissue; unbroken spiral waves are associated with VT and broken ones with VF. Several experimental studies have been carried out to determine the effects of inhomogeneities in cardiac tissue on such arrhythmias. We give a brief overview of such experiments, and then an introduction to partialdifferential-equation models for ventricular tissue. We show how different types of inhomogeneities can be included in such models, and then discuss various numerical studies, including our own, of the effects of these inhomogeneities on spiral-wave dynamics. The most remarkable qualitative conclusion of our studies is that the spiral-wave dynamics in such systems depends very sensitively on the positions of these inhomogeneities.

We report the case of a 60-year-old male with recurrent pre-syncope, referred with a provisional diagnosis of carotid sinus syndrome on the basis of a 4 s asystolic pause following carotid sinus massage. On repeat Holter monitoring there was ST-segment elevation followed by episodes of polymorphic ventricular tachycardia during a mild episode of pre-syncope. Coronary angiography showed mild right coronary artery irregularity without significant stenosis. An automatic cardioverter defibrillator was implanted and high dose combined vasodilator therapy was commenced. At follow-up 18 months after implantation, the device has recorded no episode of tachycardia and the patient reports no recurrence of symptoms.

Isolated left ventricular noncompaction is a rare cardiomyopathy that is often not recognised. So far, it is not well established how best to manage this abnormality. We describe a patient in whom the diagnosis of isolated left ventricular noncompaction was made after presentation with a subacute myocardial infarction. Because of nonsustained ventricular tachycardias during hospitalisation, which were inducible and deteriorated into ventricular fibrillation on electrophysiological examination after coronary artery bypass grafting, he received an implantable defibrillator. Whether the ventricular tachycardias were due to the myocardial infarction or to the noncompacted myocardium remains uncertain. (Neth Heart J 2007;15:109-11.).