Prognostic value of strain by feature-tracking cardiac magnetic resonance in arrhythmogenic right ventricular cardiomyopathy.

AIMS: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by ventricular dysfunction and ventricular arrhythmias (VA). Adequate arrhythmic risk assessment is important to prevent sudden cardiac death. We aimed to study the incremental value of strain by feature-tracking cardiac magnetic resonance imaging (FT-CMR) in predicting sustained VA in ARVC patients. METHODS AND RESULTS: CMR images of 132 ARVC patients (43% male, 40.6 ± 16.0 years) without prior VA were analysed for global and regional right and left ventricular (RV, LV) strain. Primary outcome was sustained VA during follow-up. We performed multivariable regression assessing strain, in combination with (i) RV ejection fraction (EF); (ii) LVEF; and (iii) the ARVC risk calculator. False discovery rate adjusted P-values were given to correct for multiple comparisons and c-statistics were calculated for each model. During 4.3 (2.0-7.9) years of follow-up, 19% of patients experienced sustained VA. Compared to patients without VA, those with VA had significantly reduced RV longitudinal (P ≤ 0.03) and LV circumferential (P ≤ 0.04) strain. In addition, patients with VA had significantly reduced biventricular EF (P ≤ 0.02). After correcting for RVEF, LVEF, and the ARVC risk calculator separately in multivariable analysis, both RV and LV strain lost their significance [hazard ratio 1.03-1.18, P > 0.05]. Likewise, while strain improved the c-statistic in combination with RVEF, LVEF, and the ARVC risk calculator separately, this did not reach statistical significance (P ≥ 0.18). CONCLUSION: Both RV longitudinal and LV circumferential strain are reduced in ARVC patients with sustained VA during follow-up. However, strain does not have incremental value over RVEF, LVEF, and the ARVC VA risk calculator.

Adrenergic and metabolic effects of electrical weapons: review and meta-analysis of human data.

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.

Sports in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy and desmosomal mutations.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a rare cardiomyopathy associated with life-threatening arrhythmias and an increased risk of sudden cardiac death. In addition to mutations in desmosomal genes, environmental factors such as exercise and sport have been implicated in the pathogenesis of the disease. Recent studies have shown that exercise may be associated with adverse outcomes in patients with ARVD/C. On the basis of current evidence, patients with ARVD/C are recommended to limit exercise irrespective of their mutation status. Some studies have suggested the presence of an entirely acquired form of the disease caused by exercise, which has been dubbed "exercise-induced ARVD/C."

Neurally mediated hypotension in systemic lupus erythematosus patients with fibromyalgia.

OBJECTIVE: Fibromyalgia (FM) is a major determinant of poor health status in systemic lupus erythematosus (SLE). FM has been shown to be associated with neurally mediated hypotension (NMH) in the general population, in which effective treatments exist. We explored whether NMH was more common in SLE patients with FM than those without. METHODS: Seventy-six SLE patients (4 male, 72 female; 1 ethnic Indian, 28 African American, 47 Caucasian; mean age 40.2 +/- 9.4 yr) were recruited and their FM status ascertained using American College of Rheumatology (ACR) classification criteria. Patients who were pregnant or deconditioned were excluded. A two-stage tilt-table test was used to detect NMH. All patients completed the SF-36 Heath Status Inventory (SF-36) and the Krupp Fatigue Severity Scale (KFSS) to evaluate their quality of life. Serological markers and the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) were recorded. Medications that might interfere with testing were temporarily withheld before the tilt-table test. RESULTS: The prevalence of NMH (first stage) in SLE patients was 47.9%. Seven patients had both NMH and postural orthostatic tachycardia syndrome. Two patients had borderline results with symptoms reproduced but an inadequate drop in systolic blood pressure by definition (a drop of at least 25 mmHg defines an abnormal response). Eighteen (23.7%) SLE patients had FM and 51 (67.1%) had at least one tender point (TP). The frequency of NMH (first or second stage) in SLE with FM was 58.3% compared with 69.4% in SLE without FM (odds ratio 0.62, 95% CI 0.16-2.37). SF-36 and KFSS scores were not significantly different in SLE patients with and without NMH. However, both scores were found to be associated with FM status (P<0.001 and P = 0.014), reflecting poor health status in the FM group. No confounding variable was found to be significantly associated with both NMH and FM. CONCLUSION: NMH is common in SLE patients with a high prevalence rate. The large increase in NMH, a form of autonomic neuropathy, in SLE, has not been explained. However, NMH has no impact on quality of life above that determined by FM, and has no statistically significant association with FM status. Identification of NMH may be important in selected patients with SLE who have chronic fatigue, but NMH cannot explain the increased prevalence of FM in SLE.

Catheter ablation for cardiac arrhythmias.

The clinical introduction of catheter ablation in 1981 revolutionized the treatment of cardiac arrhythmias. Implementation of radiofrequency as an alternative energy source, with the advantages of higher selectivity and less collateral damage, provided an expansion of catheter ablation therapy. Today the majority of arrhythmias can potentially be cured with catheter ablation therapy. The safety and efficacy of catheter ablation for treatment of AV nodal reentrant tachycardia, accessory pathway arrhythmias, focal atrial tachycardia, atrial flutter and idiopathic ventricular tachycardia, is well established. Catheter ablation for treatment of atrial fibrillation and ventricular tachycardia secondary to structural heart disease, remains an area of active research. In this article we will review the current state of knowledge about the technique, indications, and results of catheter ablation for the treatment of cardiac arrhythmias.

Guías actualizadas de la ACC/AHA para evaluación cardiovascular perioperatoria para cirugía no cardiaca / Actualized guidelines of the ACC/AHA for perioperative cardiovascular evaluation to no cardiac surgery

Estas guías representan una actualización de aquellos publicados en 1996 dirigidas a médicos que están comprometidos en el cuidado preoperatorio, operatorio y postoperatorio de pacientes que van a cirugía no cardiaca. Ellas proveen un marco de referencia para analizar el riesgo cardiaco de cirugia no cardiaca en una variedad de pacientes y situaciones quirúrgicas. El tema principal de estas guías es que la intervención preoperatoria es raramene necesaria simplemente para disminuir el riesgo de la cirugía a menos que dicha intervención sea indicada independiente del contexto preoperatorio.

Electrical induction of ventricular fibrillation for resuscitation from postcountershock pulseless and asystolic cardiac arrests.

BACKGROUND: There is increasing evidence that defibrillation from prolonged ventricular fibrillation (VF) before CPR decreases survival. It remains unclear, however, whether harmful effects are due primarily to initial countershock of ischemic myocardium or to resultant postdefibrillation rhythms (ie, pulseless electrical activity [PEA] or asystole). METHODS AND RESULTS: We induced 15 dogs into 12 minutes of VF and randomized them to 3 groups. Group 1 was defibrillated at 12 minutes and then administered advanced cardiac life support (ACLS); group 2 was allowed to remain in VF and was subsequently defibrillated after 4 minutes of ACLS; group 3 was defibrillated at 12 minutes, electrically refibrillated, and then defibrillated after 4 minutes of ACLS. All group 1 and 3 animals were defibrillated into PEA/asystole at 12 minutes. After 4 minutes of ACLS, group 2 and 3 animals were effectively defibrillated into sinus rhythm. The extension of VF in group 2 and 3 subjects paradoxically resulted in shorter mean resuscitation times (251+/-15 and 245+/-7 seconds, respectively, versus 459+/-66 seconds for group 1; P<0.05) and improved 1-hour survival (10 of 10 group 2 and 3 dogs versus 1 of 5 group 1 dogs; Fisher's exact, P<0.005) compared with more conservatively managed group 1 subjects. CONCLUSIONS: Precountershock CPR during VF appears more conducive to resuscitation than CPR during postcountershock PEA or asystole. The intentional induction of VF may prove useful in the management of PEA and asystolic arrests.

Lead configuration for defibrillator implantation in a patient with congenital heart disease and a mechanical prosthetic tricuspid valve.

The authors devised a nonthoracotomy defibrillation system for a patient with a prosthetic tricuspid valve using existing technology and previously established implantation techniques. Their lead configuration deviates substantially from existing designs in its primary use of a coronary sinus defibrillation coil and a left-sided subcutaneous array to distribute current across the ventricular myocardium.

Prospective randomized comparison of the safety and effectiveness of placement of endocardial pacemaker and defibrillator leads using the extrathoracic subclavian vein guided by contrast venography versus the cephalic approach.

The purpose of this prospective randomized study was to compare the safety and efficacy of the cephalic approach versus a contrast-guided extrathoracic approach for placement of endocardial leads. Despite an increased incidence of lead fracture, the intrathoracic subclavian approach remains the dominant approach for placement of pacemaker and implantable defibrillator leads. Although this complication can be prevented by lead placement in the cephalic vein or by lead placement in the extrathoracic subclavian or axillary vein, these approaches have not gained acceptance. A total of 200 patients were randomized to undergo placement of pacemaker or implantable defibrillator leads via the contrast-guided extrathoracic subclavian vein approach or the cephalic approach. Lead placement was accomplished in 99 of the 100 patients randomized to the extrathoracic subclavian vein approach as compared to 64 of 100 patients using the cephalic approach. In addition to a higher initial success rate, the extrathoracic subclavian vein medial approach was determined to be preferable as evidenced by a shorter procedure time and less blood loss. There was no difference in the incidence of complications. In conclusion, these results demonstrate that lead placement in the extrathoracic subclavian vein guided by contrast venography is effective and safe. It was also associated with no increased risk of complications as compared with the cephalic approach. These findings suggest that the contrast-guided approach to the extrathoracic portion of the subclavian vein should be considered as an alternative to the cephalic approach.

Laser ablation of the pulmonary veins by using a fiberoptic balloon catheter: implications for treatment of paroxysmal atrial fibrillation.

BACKGROUND AND OBJECTIVE: Focal sources of paroxysmal atrial fibrillation may be treatable by electrical isolation of the pulmonary veins from the left atrium. A new fiberoptic balloon catheter was tested as an alternative to radiofrequency catheter ablation for creation of circumferential thermal lesions at the pulmonary vein orifice. STUDY DESIGN/MATERIALS AND METHODS: In vitro and in vivo experiments were conducted in canine hearts to demonstrate efficacy and optimize ablation dosimetry. Continuous-wave, 1.06-microm, Nd:YAG laser radiation was delivered radially through diffusing optical fiber tips enclosed in a balloon catheter. During in vivo studies, the catheter was placed at the pulmonary vein orifice through a left atrial appendage sheath under X-ray fluoroscopic guidance during an open-chest procedure. Additionally, circumferential lesions in the left atrial appendage were correlated with epicardial electrograms demonstrating elimination of electrical activity. RESULTS: The pulmonary veins were successfully ablated by using laser powers of 30--50 W and irradiation times of 60--90 seconds. Transmural, continuous, and circumferential lesions were produced in the pulmonary veins in a single application without evidence of tissue vaporization or endothelial disruption. CONCLUSION: Laser ablation by using a fiberoptic balloon catheter may represent a promising alternative to radiofrequency catheter ablation for electrical isolation of the pulmonary veins from the left atrium during treatment of paroxysmal atrial fibrillation. Further development and testing of the fiberoptic catheter is warranted for possible clinical studies.

Complications associated with radiofrequency catheter ablation of cardiac arrhythmias.

Catheter ablation using radiofrequency energy has evolved as a safe and effective means for the treatment of various supraventricular and ventricular arrhythmias. Despite the overall efficacy of radiofrequency catheter ablation, cardiovascular complications can occur in a small number of patients. The purpose of this article is to review the current understanding of the risks and complications that can occur during catheter ablation procedures.

Catheter ablation for cardiac arrhythmias.

The safety and efficacy of catheter ablation for treatment of most types of cardiac arrhythmias are well established. These arrhythmias and arrhythmia substrates include AVNRT, accessory pathways, focal atrial tachycardia, atrial flutter, idiopathic ventricular tachycardia, and bundle-branch re-entry. Catheter ablation is considered as an alternative to pharmacologic therapy in the treatment of these cardiac arrhythmias.

Fludrocortisone acetate to treat neurally mediated hypotension in chronic fatigue syndrome: a randomized controlled trial.

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.

Linear lesions in myocardium created by Nd:YAG laser using diffusing optical fibers: in vitro and in vivo results.

BACKGROUND AND OBJECTIVE: Linear lesions may be necessary for successful catheter ablation of cardiac arrhythmias such as atrial fibrillation. This study uses laser energy delivered through diffusing optical fibers as an alternative to radiofrequency energy for the creation of linear lesions in cardiac tissue in a single application. STUDY DESIGN/MATERIALS AND METHODS: Samples of canine myocardium were placed in a heated, circulating saline bath and irradiated with a 1.06-microm, continuous-wave Nd:YAG laser during in vitro studies. Laser ablation was then performed in vivo on the epicardial surface of the right ventricle during an open-chest procedure by using similar ablation parameters. Laser energy was delivered to the tissue by being diffused radially through flexible optical fiber tips oriented parallel to the tissue surface. Histology and temperature measurements verified transmurality, continuity, and linearity of the lesions. RESULTS: Peak tissue temperatures measured in vitro remained low (51 +/- 1 degrees C at the endocardial surface, 61 +/- 6 degrees C in the mid-myocardium, and 55 +/- 6 degrees C at the epicardial surface) with no evidence of tissue charring or vaporization. Lesion dimensions produced in vitro and in vivo were similar (depth, 6 mm; width, 8-10 mm; length, 16-22 mm), demonstrating that tissue perfusion in vivo did not significantly alter the heating. CONCLUSION: Long linear lesions, necessary for duplication of the surgical maze procedure during catheter ablation of atrial fibrillation, may be created by using laser radiation delivered through flexible diffusing optical fiber tips. Further development of steerable catheters for endocardial atrial ablation and studies correlating thermal damage zones with electrophysiologic indicators of irreversible conduction block are warranted.