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Introduction: Electronic control with the CEW (conducted electrical weapon) has gained widespread acceptance as the preferred force option due to its significant injury reduction. However, a CEW application does stress the human body. In the case of the CEW, the human body response is similar to the challenge of physical exercise combined with emotional stress over a very short time interval. There has been concern whether the tension of the skeletal-muscle system together with the emotional stress of being exposed to the effects of a CEW, can lead to severe metabolic dysfunction.Methods: A systematic and careful search of the MedLine database was performed to find publications describing pathophysiological effects of CEWs. Additional publications were collected through a manual search of reference lists in retrieved articles. After preliminary exclusions, we carefully reviewed the remaining publications and found 24 papers reporting prospective human clinical research data on adrenergic, ventilation, or metabolic effects. Where there were multiple studies on the same endpoints, we performed meta-analyses.Results: A CEW exposure provides a clinically insignificant increase in heart rate (7.5 BPM) and a drop in both systolic and diastolic blood pressure. Alpha-amylase goes down but cortisol levels increase—both epinephrine and norepinephrine levels are increased by levels similar to mild exercise. A CEW exposure increases ventilation but does not appear to interfere with gas exchange. Lactate is increased slightly while the pH is decreased slightly with changes equivalent to mild exercise. The lactate and pH changes appear quickly and do not appear to be affected by increasing the exposure duration from 5 to 30 s.Conclusions: Thorough review and meta-analyses show that electrical weapon exposures have mixed and mild adrenergic effects. Ventilation is increased and there are metabolic changes similar to mild exercise. [ABSTRACT FROM AUTHOR]

Context: Patients with chronic fatigue syndrome (CFS) are more likely than healthy persons to develop neurally mediated hypotension (NMH) in response to prolonged orthostatic stress.Objective: To examine the efficacy of fludrocortisone acetate as monotherapy for adults with both CFS and NMH.Design: Randomized, double-blind, placebo-controlled trial conducted between March 1996 and February 1999.Setting: Two tertiary referral centers in the United States.Patients: One hundred individuals aged 18 to 50 years who satisfied Centers for Disease Control and Prevention criteria for CFS and had NMH provoked during a 2-stage tilt-table test. Eighty-three subjects had adequate outcome data to assess efficacy.Intervention: Subjects were randomly assigned to receive fludrocortisone acetate, titrated to 0.1 mg/d (n = 50) or matching placebo (n = 50) for 9 weeks, followed by 2 weeks of observation after discontinuation of therapy.Main Outcome Measure: Proportion of subjects in each group with at least a 15-point improvement on a 100-point global wellness scale.Results: Baseline demographic and illness characteristics between the groups were similar; CFS had been present for at least 3 years in 71%. Using an intention-to-treat analysis, 7 subjects (14%) treated with fludrocortisone experienced at least a 15-point improvement in their wellness scores compared with 5 (10%) among placebo recipients (P =.76). No differences were observed in several other symptom scores or in the proportion with normal follow-up tilt test results at the end of the treatment period.Conclusions: In our study of adults with CFS, fludrocortisone as monotherapy for NMH was no more efficacious than placebo for amelioration of symptoms. Failure to identify symptomatic improvement with fludrocortisone does not disprove the hypothesis that NMH could be contributing to some of the symptoms of CFS. Further studies are needed to determine whether other medications or combination therapy are more effective in treating orthostatic intolerance in patients with CFS. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Typical atrial flutter (AFL) can be cured by catheter ablation of the cavotricuspid isthmus (CTI). The surface electrocardiogram (ECG) is not always diagnostic of isthmus dependence of AFL. The aim of this study was to evaluate clinical parameters for the prediction of isthmus-dependent AFL. METHODS AND RESULTS: Sixty consecutive adult patients without suspected atriotomy-related AFL, congenital heart disease, or previous AFL ablation, referred for catheter ablation of presumed typical AFL were studied. All patients had distinct flutter waves in the inferior leads, suggestive of CTI-dependent AFL, either on presentation to the electrophysiology (EP) lab or documented on prior ECG. Electrophysiology study was performed in the standard fashion. Patients who presented to the EP laboratory not in AFL underwent arrhythmia induction with a burst pacing protocol. A clinical history of persistent AFL (P = 0.0001) and existence of AFL on presentation to the EP laboratory (P = 0.0001) were strong predictors of CTI dependence. History of atrial fibrillation (P = 0.19), structural heart disease (P = 0.6), hypertension (P = 0.4), and previous cardiac surgery (P = 0.5), as well as the nature of AFL-related symptoms (P = 0.5), were not predictors of CTI-dependent AFL documented during EP study. CONCLUSION: In patients with ECG suggestive of typical AFL, the presence of persistent rather than paroxysmal AFL and presentation to the EP laboratory in AFL are strong predictors of CTI-dependent AFL. A paroxysmal pattern of AFL predicts noninducibility of CTI-dependent AFL during EP study. CTI ablation may therefore be less effective in these patients. [ABSTRACT FROM AUTHOR]

For most types of supraventricular arrhythmias medical treatment with antiarrythmic drugs is not completely effective. In addition to poor or sporadic efficacy, such drugs can be associated with a number of bothersome and even fatal side effects, proarrhythmia, cost, and inconvenience. Over the past two decades, catheter ablation has evolved from a highly experimental technique to first line treatment for many cardiac arrhythrnias. During radiofrequency ablation, current flows into the tissue underlying the active electrode in alternating direction at high frequency.

Vasovagal syncope is a common disorder of autonomic cardiovascular regulation. Many pharmacologic agents have been proposed as effective in the management of this condition based on nonrandomized clinical trials. Notably, only 3 agents--atenolol, midodrine, and paroxetine--have demonstrated efficacy in the treatment of vasovagal syncope in at least 1 prospective, randomized, placebo-controlled clinical trial. Other therapies commonly used in treating syncope include increased salt and fluid intake and fludrocortisone. In this review, we provide a summary of currently available data that support or question the use of various pharmacologic agents for treatment of vasovagal syncope. [ABSTRACT FROM AUTHOR]

Presents a study designed to determine the feasibility of an abbreviated approach to the treatment of patients with paroxysmal supraventricular tachycardias or the Wolff-Parkinson-White syndrome, aimed at combining a diagnostic and therapeutic procedure into a single electrophysiologic test. Background; Methods; Results; Conclusions.

A substantial body of clinical evidence now supports an association between various forms of hypotension and both idiopathic chronic fatigue and the chronic fatigue syndrome (CFS). Patients with CFS have a high prevalence of neurally mediated hypotension, and open treatment of this autonomic dysfunction has been associated with improvements in CFS symptoms. Randomized trials are now in progress to evaluate the efficacy of treatments directed at neurally mediated hypotension in those with CFS patients, and the results of these trials should help guide more basic inquiries into the mechanisms of orthostatic intolerance in affected individuals. [ABSTRACT FROM AUTHOR]

The precise techniques employed in the electrophysiology laboratory influence the nature of the electrograms that are recorded during mapping procedures. Unipolar recordings that are minimally filtered can be useful for mapping focal arrhythmia sources, but have substantial far-field signal that can obscure low-amplitude signals of interest in abnormal regions. Bipolar recordings are standard in most laboratories because rejection of far-field signal facilitates identification of local potentials in abnormal areas, but the signal of interest can be beneath either recording electrode and far-field signals do occur. Simultaneously obtained unipolar recordings are a useful adjunct to bipolar recordings in some situations. High pass filtering and digital sampling also influence electrogram characteristics. High pass filtering of unipolar recordings can be useful to reduce far-field components, but limits inferences from electrogram morphology. [ABSTRACT FROM AUTHOR]

Increased attention is now being focused on developing new technologies to cure atrial fibrillation using catheter ablation techniques. The performance of a MAZE-type procedure using standard catheter ablation technologies is arduous and is associated with an unacceptable risk of complications. The Guidant Heart Rhythm Technologies Linear Ablation System was developed to create long transmural linear lesions. Unique features of this system include the availability of different preshaped multi-electrode steerable ablation catheters, the use of phased radiofrequency (RF) energy, and the control of RF output by varying the duty cycle. A prospective multicenter clinical trial to evaluate the safety and efficacy of a right atrial ablation procedure using this technology to treat atrial fibrillation is currently underway. To date, 15 patients have been enrolled and the procedure was acutely effective in 14 of 15 patients with no complications. Atrial fibrillation has recurred during short-term follow-up in 12 of 15 patients, a not surprising result, because this initial phase of testing involved only right-sided ablation. The early results of the phase I clinical trial confirm the findings of others that successful ablation of chronic atrial fibrillation is likely to require a left atrial approach. This clinical trial, as well as others that are currently underway, will be invaluable in the continuing development of catheter ablation of atrial fibrillation and, ultimately, in determining if the routine use of this therapeutic tool can become a reality. [ABSTRACT FROM AUTHOR]

Objectives: The aims of this study were to determine the spectrum and prevalence of "background genetic noise" in the arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) genetic test and to determine genetic associations that can guide the interpretation of a positive test result.Background: ARVC is a potentially lethal genetic cardiovascular disorder characterized by myocyte loss and fibrofatty tissue replacement of the right ventricle. Genetic variation among the ARVC susceptibility genes has not been systematically examined, and little is known about the background noise associated with the ARVC genetic test.Methods: Using direct deoxyribonucleic acid sequencing, the coding exons/splice junctions of PKP2, DSP, DSG2, DSC2, and TMEM43 were genotyped for 93 probands diagnosed with ARVC from the Netherlands and 427 ostensibly healthy controls of various ethnicities. Eighty-two additional ARVC cases were obtained from published reports, and additional mutations were included from the ARVD/C Genetic Variants Database.Results: The overall yield of mutations among ARVC cases was 58% versus 16% in controls. Radical mutations were hosted by 0.5% of control individuals versus 43% of ARVC cases, while 16% of controls hosted missense mutations versus a similar 21% of ARVC cases. Relative to controls, mutations in cases occurred more frequently in non-Caucasians, localized to the N-terminal regions of DSP and DSG2, and localized to highly conserved residues within PKP2 and DSG2.Conclusions: This study is the first to comprehensively evaluate genetic variation in healthy controls for the ARVC susceptibility genes. Radical mutations are high-probability ARVC-associated mutations, whereas rare missense mutations should be interpreted in the context of race and ethnicity, mutation location, and sequence conservation. [ABSTRACT FROM AUTHOR]

Context: Antiarrhythmic drugs are commonly used for prevention of recurrent atrial fibrillation (AF) despite inconsistent efficacy and frequent adverse effects. Catheter ablation has been proposed as an alternative treatment for paroxysmal AF.Objective: To determine the efficacy of catheter ablation compared with antiarrhythmic drug therapy (ADT) in treating symptomatic paroxysmal AF.Design, Setting, and Participants: A prospective, multicenter, randomized (2:1), unblinded, Bayesian-designed study conducted at 19 hospitals of 167 patients who did not respond to at least 1 antiarrhythmic drug and who experienced at least 3 AF episodes within 6 months before randomization. Enrollment occurred between October 25, 2004, and October 11, 2007, with the last follow-up on January 19, 2009.Intervention: Catheter ablation (n = 106) or ADT (n = 61), with assessment for effectiveness in a comparable 9-month follow-up period.Main Outcome Measures: Time to protocol-defined treatment failure. The proportion of patients who experienced major treatment-related adverse events within 30 days of catheter ablation or ADT was also reported.Results: At the end of the 9-month effectiveness evaluation period, 66% of patients in the catheter ablation group remained free from protocol-defined treatment failure compared with 16% of patients treated with ADT. The hazard ratio of catheter ablation to ADT was 0.30 (95% confidence interval, 0.19-0.47; P < .001). Major 30-day treatment-related adverse events occurred in 5 of 57 patients (8.8%) treated with ADT and 5 of 103 patients (4.9%) treated with catheter ablation. Mean quality of life scores improved significantly in patients treated by catheter ablation compared with ADT at 3 months; improvement was maintained during the course of the study.Conclusion: Among patients with paroxysmal AF who had not responded to at least 1 antiarrhythmic drug, the use of catheter ablation compared with ADT resulted in a longer time to treatment failure during the 9-month follow-up period.Trial Registration: clinicaltrials.gov Identifier: NCT00116428. [ABSTRACT FROM AUTHOR]

Background: Transseptal catheterization (TSC) is performed during catheter ablation involving the lefthand side of the heart. TSC causes a transient iatrogenic atrial septal defect that can predispose patients to migraine episodes. However, isolated migraine aura episodes in patients undergoing TSC have not been described. Methods: Five hundred seventy-one procedures involving TSC were performed over a 3-year duration. Of these, 3 patients presented with visual symptoms in the first month after the procedure. One patient underwent a TSC during catheter ablation of left-sided accessory pathway and 2 patients underwent TSC during catheter ablation of atrial fibrillation. Results: The incidence of migraine aura in this patient population was 0.5%. In the first week after the procedure, all 3 patients experienced transient reversible visual symptoms of scintillating scotoma consistent with migraine aura. None of the patients had an associated headache. The workup for stroke or transient ischemic attack was negative. All the patients recovered completely within 1 hour of symptom onset and did not have any sequelae. Conclusion: This study reports for the first time the incidence and outcomes of isolated migraine aura in patients undergoing electrophysiology procedures involving TSC. For post-TSC patients who present with atypical neurologic symptoms, especially 'scintillating scotoma,' once transient ischemic attack or other neurologic event has been ruled out, an aura associated with the TSC should be entertained as a possible diagnosis. Electrophysiologists who perform TSC, need to be aware of this phenomenon and can reassure the patients of the transient and benign nature. [ABSTRACT FROM AUTHOR]

Atrial tachycardias represent the second front of atrial fibrillation (AF) ablation. They are frequently encountered during the index ablation for patients with persistent AF and are common following ablation of persistent AF, occurring in half of all patients who have had AF successfully terminated. An atrial tachycardia is rightly seen as a failure of AF ablation, as these tachycardias are poorly tolerated by patients. This article describes a simple, practical approach to diagnosis and ablation of these atrial tachycardias. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to determine the extent of left ventricular (LV) involvement in individuals predisposed to developing arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), and to investigate novel morphologic variants of ARVD/C.Background: The discovery of desmosomal mutations associated with ARVD/C has led researchers to hypothesize equal right ventricular (RV) and LV affliction in the disease process.Methods: Thirty-eight (age 30 +/- 17 years; 18 males) family members of 12 desmosomal mutation-carrying ARVD/C probands underwent genotyping and cardiac magnetic resonance imaging (CMR). The CMR investigators were blinded to clinical and genetic data.Results: Twenty-five individuals had mutations in PKP2, DSP, and/or DSG2 genes. RV abnormalities were associated with the presence of mutation(s) and with disease severity determined by criteria (minor = 1; major = 2) points for ARVD/C diagnosis. The only LV abnormality detected, the presence of intramyocardial fat, was present in 4 individuals. Each of these individuals was a mutation carrier, whereas 1 had no previously described ARVD/C-related abnormality. On detailed CMR, a focal "crinkling" of the RV outflow tract and subtricuspid regions ("accordion sign") was observed in 60% of the mutation carriers and none of the noncarriers (p < 0.001). The sign was present in 0%, 37%, 71%, and 75% of individuals who met 1, 2, 3, and 4+ criteria points, respectively (p < 0.01).Conclusions: Despite a possible LV involvement in ARVD/C, the overall LV structure and function are well preserved. Independent LV involvement is of rare occurrence. The accordion sign is a promising tool for early diagnosis of ARVD/C. Its diagnostic utility should be confirmed in larger cohorts. [ABSTRACT FROM AUTHOR]

Introduction: Catheter ablation of the pulmonary veins (PVs) for prevention of recurrent atrial fibrillation requires precise anatomic information. We describe the characteristics of a new anatomic variant of PV anatomy using magnetic resonance angiography. Methods and Results: A 1.5-T magnetic resonance imaging system with a body coil or a torso phased- array coil was used before and after gadolinium injection. Magnetic resonance angiograms were acquired with a breath-hold three-dimensional fast spoiled gradient-echo imaging sequence in the coronal plane. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. A newly described variant PV ascending from the roof of the left atrium was found in 3 of 91 subjects. The mean ostial diameter of the roof PV was 7 ± 2 mm, the mean distance from the ostium to the first branching point was 22 ± 8.5 mm, and the mean distance to the right superior PV was 3.3 ± 0.6 mm. Conclusion: We refer to the newly described variant of PV anatomy as the 'right top pulmonary vein.' It is important to be aware of this anatomic pattern to avoid inadvertent catheter intubation, which can result in misleading mapping results and PV stenosis. [ABSTRACT FROM AUTHOR]

Neurocardiogenic syncope is the most common cause of acute loss of consciousness in adults. The present study attempted to identify neuroendocrine and hemodynamic changes before syncope that could therefore play a pathophysiologic role. Twenty-five patients referred for chronic orthostatic intolerance had plasma catecholamines measured serially; 21 patients during tilt-table testing (evoking syncope in 13) and 4 others with spontaneous syncope while supine. Forearm blood flow was measured by impedance plethysmography. All 12 patients with blood sampled before tilt-induced syncope had progressive, marked increases in plasma epinephrine levels (mean 11 times baseline, p <0.0001) before syncope. Simultaneously obtained norepinephrine levels increased to a much smaller extent than did epinephrine levels ("sympathoadrenal imbalance"). In the same patients, forearm vascular resistance decreased by 21% before syncope. Proportionate changes in forearm vascular resistance before syncope correlated negatively with those in the epinephrine:norepinephrine ratio (r = -0.75, p = 0.005). Patients without syncope had forearm vasoconstriction and no sympathoadrenal imbalance during tilt. Patients with syncope while supine also had sympathoadrenal imbalance before loss of consciousness. Sympathoadrenal imbalance precedes tilt-evoked and spontaneous neurocardiogenic syncope and correlates with concurrent skeletal muscle vasodilation. Sympathoadrenal imbalance may contribute to hemodynamic derangements precipitating neurocardiogenic syncope. [ABSTRACT FROM AUTHOR]

The consensus process that culminated in this symposium established an algorithm to guide the diagnosis and treatment of patients with vasovagal syncope and related disorders. In some patients, the hemodynamic response to standing may identify an abnormality-postural orthostatic tachycardia syndrome or orthostatic hypotension-that can often be treated without further testing. When the response to standing is normal, tilt-table testing may be useful in making the diagnosis of vasovagal syncope and guiding treatment. In some patients, however, the diagnosis is clear from the history, and tilt-table testing may not be necessary. Not all patients with vasovagal syncope need to be treated, and many can be treated effectively with education, reassurance, and a simple increase in dietary salt. In evaluating the results of tilt-table testing, an important consideration is the distinction between vasovagal syncope and the dysautonomic response to tilt characterized by a gradual and progressive decrease in blood pressure that leads to syncope. Current practice patterns suggest that beta blockers, fludrocortisone, and midodrine, are commonly used to treat patients with vasovagal syncope, and patients with the dysautonomic response are generally treated with fludrocortisone and midodrine. Permanent pacing with specialized pacing algorithms should be considered for patients with frequent vasovagal syncope that is refractory to medical therapy. The guidelines proposed here are an amalgam of clinical experience, expert opinion, and research evidence; however, they do not suggest a standard of care for all patients. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify factors that predict fluoroscopy duration and radiation exposure during catheter ablation procedures. The patient population included 859 patients who participated in the Atakr Ablation System clinical trial at 1 of 9 centers (398 male and 461 female patients, aged 36 +/- 21 years). Each patient underwent catheter ablation of an accessory pathway, the atrioventricular junction, or atrioventricular nodal reentrant tachycardia using standard techniques. The duration of fluoroscopy was 53 +/- 50 minutes. Factors identified as independent predictors of fluoroscopy duration included patient age and sex, the success or failure of the ablation procedure, and the institution at which the ablation was performed. Catheter ablation in adults required longer fluoroscopy exposure than it did in children. Men required longer durations of fluoroscopy exposure than did women. The mean estimated "entrance" radiation dose was 1.3 +/- 1.3 Sv. The dose needed to cause radiation skin injury was exceeded during 22% of procedures. The overall mean effective absorbed dose from catheter ablation procedures was 0.025 Sv for female patients and 0.017 Sv for male patients. This degree of radiation exposure would result in an estimated 1,400 excess fatal malignancies in female patients and 2,600 excess fatal malignancies in male patients per 1 million patients. [ABSTRACT FROM AUTHOR]

The article presents a study focusing on the safety of magnetic resonance imaging (MRI) in patients with pacemakers or defibrillators. The study showed that some patients with pacemakers or defibrillators can safely have MRI, provided that they are carefully evaluated beforehand and are monitored during and after the test by doctors and nurses with expertise in this area.

Pulmonary vein (PV) isolation using radiofrequency (RF) ablation can induce PV stenosis. Cryoablation may offer a safer alternative energy source for PV isolation. PV isolation with cryoablation was attempted in 31 patients with paroxysmal atrial fibrillation (AF). Event monitors were used to measure the AF episode burden. Serial spiral CT scans were obtained to monitor PV stenosis pre- and postcryoablation. Cryoablation was immediately successful for PV isolation in 29 of 31 patients (94%), with 5.9 +/- 1.2 months of follow-up. Additional RF ablation was performed for AF recurrences in seven patients. The remaining 22 patients with a single cryoablation procedure demonstrated a time-dependent, long-term reduction in the frequency of AF episodes. At 6 months of follow-up, 18 of 22 of cryo-treated only patients (82%) were free of symptomatic AF episodes, and antiarrhythmic drugs were discontinued in 12 of 22 patients. Serial spiral CT scans demonstrated no change in the cryo-treated PV ostial diameter. PV cryoablation was effective to control paroxysmal AF in most patients. Early recurrences of AF postcryoablation were common, though tended to resolve within 6 months postablation, consistent with a process of reverse atrial remodeling. Cryoablation of the PVs did not cause PV stenosis or other serious adverse events. [ABSTRACT FROM AUTHOR]