Determinants of the outcome of electrophysiologic study in patients with ventricular tachyarrhythmias

To determine those factors predictive of the ability to both initiate and suppress ventricular tachyarrhythmias during electrophysiologic study, the results of programmed cardiac stimulation were evaluated in 261 patients: 66 presenting with nonsustained ventricular tachycardia, 91 with sustained ventricular tachycardia and 104 with ventricular fibrillation. Multivariate logistic regression analysis revealed that the presenting arrhythmia was a potent and independent predictor of the ability to provoke ventricular arrhythmias at electrophysiologic study; a history of myocardial infarction and male sex were also significant independent predictors. Of patients presenting with sustained ventricular tachycardia, 89% (81 of 91) had inducible ventricular arrhythmias compared with 61 (40 of 66) and 66% (69 of 104) of patients with nonsustained ventricular tachycardia and ventricular fibrillation, respectively.Complete suppression of inducible arrhythmias could be achieved in only 52% (34 of 66) of patients with sustained ventricular tachycardia, compared with 73 (24 of 33) and 75% (46 of 61) of patients presenting with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Multivariate analysis showed that the major independent determinants of the ability to suppress inducible arrhythmias were the number of drug trials performed before electrophysiologic study (inversely correlated) and the nature of the induced arrhythmia.The nature of the presenting clinical arrhythmia is, therefore, a highly significant and independent predictor of the ability to induce ventricular arrhythmias during electrophysiologic testing and an important determinant of the ability to suppress induced arrhythmias in patients with spontaneous ventricular tachyarrhythmias

960-86 Implications of Alternative Classifications of Sudden Cardiac Death: A Prospective Analysis of 109 Deaths in Defibrillator Trials

In order to explore the implications of using varied definitions of sudden cardiac death (SCD), a classification (CL) committee (3 cardiologists) prospectively evaluated 109 deaths over a period of 19 months in patients with an implantable cardioverter defibriliator (ICD). The basis for CL was the CAST approach with additional assessments of the consequences of considering autopsy and ICD interrogation information. Concordance and/or discordance between committee members was recorded.ResultsOf the 834 patients followed for 19 months, there were 109 deaths: 17 were classified SCD, 51 non-SCD. and 40 non-cardiac. Of the deaths classified as SCD, 10/17 were unwitnessed as compared to 6/51 non-SCD and 3/40 non-cardiac deaths; p < 0.001. ICD detections occurred in 5/17 SCD <1 hour, 7/17 SCD <6 hours; therefore, 10/17 SCD had no ICD detection or information available. There was committee discordance in 5/17 SCD compared to 18/51 non-SCD and 16/40 non-cardiac. SCD rates as high as 3.6% (30/834) can be estimated if all SCD cases Cl by ≥1 member was counted as SCD. Likewise. a SCD rate as low as 0.8% (7/834) is possible if SCD is limited to witnessed SCD ≤1 hour; (a 4-fold difference). Autopsy information was available in 29/109 deaths. In 7 cases, autopsy findings resulted in changing a “SCD” CL (5 witnessed; 2 unwitnessed) to either non-SCD or non-cardiac [ruptured abdominal (N=21 or thoracic aortic (N=1) aneurysm, acute MI (N=1), cerebral infarction (N=1). pulmonary embolism (N=2)]. Thus, had autopsy information been unavailable or not considered, the SCD rate would have increased to 24/834 12.9%). ICD interrogation was unavailable in 51/109 (47%), most commonly due to being buried with the patient or programmed off prior to death.ConclusionA 4-fold spectrum of SCD rates is possible to report from the identical data-set. ICD interrogation has significant limitations for use in death CL, in contrast to its utility in clinical management. Autopsy results clarify cause-specific mortality in deaths that are temporally quite “sudden.” Total mortality is the most objective primary end point

ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices: Summary article. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to update the 1998 pacemaker guidelines)

The current update of the ACC/AHA/NASPE Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices includes several significant changes in the recommendations and in the supporting narrative portion. In this summary, we list the updated recommendations along with the respective 1998 recommendations, each one accompanied by a brief comment outlining the rationale for the changes, additions, or deletions. All new or revised recommendations are listed in the second column and appear in boldface type. References that support either the 1998 recommendations that have not changed or the new or revised recommendations are noted in parentheses at the end of each recommendation. The reader is referred to the full-text version of the guidelines posted on the American College of Cardiology (ACC), American Heart Association (AHA), and North American Society for Pacing and Electrophysiology (NASPE) World Wide Web sites for a more detailed exposition of the rationale for these changes. In addition to the recommendation changes listed here, this update includes an expanded section on the selection of pacemakers and implantable cardioverter-defibrillators (ICDs) that reflects the technical advances that have taken place since 1998. A brief expanded summary of pacemaker follow-up procedures is also new to these guidelines. For both of these expanded sections, the reader is referred to the online full-text version

Association analysis in over 329,000 individuals identifies 116 independent variants influencing neuroticism

Neuroticism is a relatively stable personality trait characterized by negative emotionality (for example, worry and guilt)1; heritability estimated from twin studies ranges from 30 to 50%2, and SNP-based heritability ranges from 6 to 15%3,4,5,6. Increased neuroticism is associated with poorer mental and physical health7,8, translating to high economic burden9. Genome-wide association studies (GWAS) of neuroticism have identified up to 11 associated genetic loci3,4. Here we report 116 significant independent loci from a GWAS of neuroticism in 329,821 UK Biobank participants; 15 of these loci replicated at P < 0.00045 in an unrelated cohort (N = 122,867). Genetic signals were enriched in neuronal genesis and differentiation pathways, and substantial genetic correlations were found between neuroticism and depressive symptoms (rg = 0.82, standard error (s.e.) = 0.03), major depressive disorder (MDD; rg = 0.69, s.e. = 0.07) and subjective well-being (rg = –0.68, s.e. = 0.03) alongside other mental health traits. These discoveries significantly advance understanding of neuroticism and its association with MDD

The effects of acute leucine or leucine–glutamine co-ingestion on recovery from eccentrically biased exercise

This study investigated the effects of leucine or leucine + glutamine supplementation on recovery from eccentric exercise. In a double-blind independent groups design, 23 men were randomly assigned to a leucine (0.087 g/kg; n = 8), leucine + glutamine (0.087 g/kg + glutamine 0.3 g/kg; n = 8) or placebo (0.3 g/kg maltodextrin; n = 7) group. Participants performed 5 sets of drop jumps, with each set comprising 20 repetitions. Isometric knee-extensor strength, counter-movement jump (CMJ) height, delayed-onset muscle soreness (DOMS) and creatine kinase (CK) were measured at baseline, 1, 24, 48 h and 72 h post-exercise. There was a time × group interaction for isometric strength, CMJ and CK (P < 0.05), with differences between the leucine + glutamine and placebo group at 48 h and 72 h for strength (P = 0.013; d = 1.43 and P < 0.001; d = 2.06), CMJ (P = 0.008; d = 0.87 and P = 0.019; d = 1.17) and CK at 24 h (P = 0.012; d = 0.54) and 48 h (P = 0.010; d = 1.37). The leucine group produced higher strength at 72 h compared to placebo (P = 0.007; d = 1.65) and lower CK at 24 h (P = 0.039; d = 0.63) and 48 h (P = 0.022; d = 1.03). Oral leucine or leucine + glutamine increased the rate of recovery compared to placebo after eccentric exercise. These findings highlight potential benefits of co-ingesting these amino acids to ameliorate recovery

ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Writing Committee to revise the ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemakers and antiarrhythmia devices)

This revision of the “ACC/AHA/NASPE Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices” updates the previous versions published in 1984, 1991, 1998, and 2002. Revision of the statement was deemed necessary for multiple reasons: 1) Major studies have been reported that have advanced our knowledge of the natural history of bradyarrhythmias and tachyarrhythmias, which may be treated optimally with device therapy; 2) there have been tremendous changes in the management of heart failure that involve both drug and device therapy; and 3) major advances in the technology of devices to treat, delay, and even prevent morbidity and mortality from bradyarrhythmias, tachyarrhythmias, and heart failure have occurred

Genetic variation and exercise-induced muscle damage: implications for athletic performance, injury and ageing.

Prolonged unaccustomed exercise involving muscle lengthening (eccentric) actions can result in ultrastructural muscle disruption, impaired excitation-contraction coupling, inflammation and muscle protein degradation. This process is associated with delayed onset muscle soreness and is referred to as exercise-induced muscle damage. Although a certain amount of muscle damage may be necessary for adaptation to occur, excessive damage or inadequate recovery from exercise-induced muscle damage can increase injury risk, particularly in older individuals, who experience more damage and require longer to recover from muscle damaging exercise than younger adults. Furthermore, it is apparent that inter-individual variation exists in the response to exercise-induced muscle damage, and there is evidence that genetic variability may play a key role. Although this area of research is in its infancy, certain gene variations, or polymorphisms have been associated with exercise-induced muscle damage (i.e. individuals with certain genotypes experience greater muscle damage, and require longer recovery, following strenuous exercise). These polymorphisms include ACTN3 (R577X, rs1815739), TNF (-308 G>A, rs1800629), IL6 (-174 G>C, rs1800795), and IGF2 (ApaI, 17200 G>A, rs680). Knowing how someone is likely to respond to a particular type of exercise could help coaches/practitioners individualise the exercise training of their athletes/patients, thus maximising recovery and adaptation, while reducing overload-associated injury risk. The purpose of this review is to provide a critical analysis of the literature concerning gene polymorphisms associated with exercise-induced muscle damage, both in young and older individuals, and to highlight the potential mechanisms underpinning these associations, thus providing a better understanding of exercise-induced muscle damage

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery