Associations of social and cognitive-behavioral variables with disinhibited eating and anxiety: An ecological momentary assessment study.

OBJECTIVE: Among adolescents, disinhibited eating and anxiety commonly co-occur. Precision intervention approaches targeting unique mechanistic vulnerabilities that contribute to disinhibited eating and anxiety may therefore be helpful. However, the effectiveness of such interventions hinges on knowledge of between- and within-person associations related to disinhibited eating, anxiety, and related processes. METHOD: A sample of 39 adolescent females (12-17 years) with elevated anxiety and above-average weight (BMI %ile ≥ 75th) completed measures of theoretically driven social and cognitive-behavioral variables, disinhibited eating, and anxiety via ecological momentary assessment over 7 days. Data were analyzed using mixed-effects models. RESULTS: Between-person differences in social stressors were linked to emotional eating, eating in the absence of hunger, and anxiety, whereas between-person differences in negative thoughts were associated with all disinhibited eating variables and anxiety. Between-person differences in avoidance were not related to any outcome. Additionally, between-person differences in social stressors and negative thoughts-as well as within-person deviations (from person-average levels) of social stressors, negative thoughts, and avoidance-were associated with anxiety. In turn, between-person differences in anxiety predicted eating in the absence of hunger and emotional eating, and within-person deviations in anxiety were associated with emotional eating at any given time point. DISCUSSION: Findings support elements of both the interpersonal and cognitive-behavioral models of disinhibited eating. Differential trigger effects on anxiety, both at the between- and within-person levels, and significant associations between anxiety and all eating-related outcomes, highlight the potential utility of interventions targeting individual differences in sensitivity to anxiety triggers. PUBLIC SIGNIFICANCE: Findings provide support for the interpersonal and cognitive-behavioral models of disinhibited eating, highlighting anxiety as a salient vulnerability and potential mechanistic factor underlying disinhibited eating. Social, cognitive, and behavioral variables were differentially related to anxiety across participants, suggesting potential for future intervention tailoring and intervention selection based on adolescents' sensitivity to anxiety as a trigger for disinhibited eating behavior.

Autonomic indices and loss-of-control eating in adolescents: an ecological momentary assessment study.

BACKGROUND: Loss-of-control (LOC) eating commonly develops during adolescence, and it predicts full-syndrome eating disorders and excess weight gain. Although negative emotions and emotion dysregulation are hypothesized to precede and predict LOC eating, they are rarely examined outside the self-report domain. Autonomic indices, including heart rate (HR) and heart rate variability (HRV), may provide information about stress and capacity for emotion regulation in response to stress. METHODS: We studied whether autonomic indices predict LOC eating in real-time in adolescents with LOC eating and body mass index (BMI) ⩾70th percentile. Twenty-four adolescents aged 12-18 (67% female; BMI percentile mean ± standard deviation = 92.6 ± 9.4) who reported at least twice-monthly LOC episodes wore biosensors to monitor HR, HRV, and physical activity for 1 week. They reported their degree of LOC after all eating episodes on a visual analog scale (0-100) using a smartphone. RESULTS: Adjusting for physical activity and time of day, higher HR and lower HRV predicted higher self-reported LOC after eating. Parsing between- and within-subjects effects, there was a significant, positive, within-subjects association between pre-meal HR and post-meal LOC rating. However, there was no significant within-subjects effect for HRV, nor were there between-subjects effects for either electrophysiologic variable. CONCLUSIONS: Findings suggest that autonomic indices may either be a marker of risk for subsequent LOC eating or contribute to LOC eating. Linking physiological markers with behavior in the natural environment can improve knowledge of illness mechanisms and provide new avenues for intervention.

Exertional-Related Sudden Cardiac Death in a Young, Presumed Healthy, and Medically Screened Population: A Military Case Series.

ABSTRACT: Sudden cardiac death (SCD) is defined as death from cardiac causes with loss of consciousness occurring within 1 hour of a change in cardiovascular status. As subset, SCD associated with physical exertion (SCD/E) can be defined as a cardiac event whose symptoms start during or within 1 hour of physical exertion. The US military represents a unique opportunity for studying SCD/E because of medical screening at recruitment, mandatory physical training, an active surveillance system, and centralized autopsy services. Because of medical screening, recruits are presumed healthy, but significant conditions can go undetected. We present 4 diverse cases of SCD/E in the military setting. Sudden cardiac death associated with physical exertion is often the first indication of a serious occult cardiac pathology. Postmortem genetic testing revealed a causative pathogenic mutation in 1 of 4 cases, enabling genetic testing of family members to prevent similar catastrophic loss of life, underscoring the importance of postmortem evaluation including genetic testing. Further investigations will help direct screening and prevention to capture those at risk for SCD. The cases presented in this series are a sample of the diverse etiologies and contexts surrounding SCD/E in the military setting that have been captured by Armed Forces Medical Examiner System.

Traumatic injury and atrial fibrillation among deployed service members.

INTRODUCTION: Atrial fibrillation and atrial flutter (AF/AFL), the most common atrial arrhythmias, have never been examined in combat casualties. In this study, we investigated the impact of traumatic injury on AF/AFL among service members with deployment history. METHODS: Sampled from the Department of Defense (DoD) Trauma Registry (n = 10,000), each injured patient in this retrospective cohort study was matched with a non-injured service member drawn from the Veterans Affairs/DoD Identity Repository. The primary outcome was AF/AFL diagnosis identified using ICD-9-CM and ICD-10-CM codes. Competing risk regressions based on Fine and Gray subdistribution hazards model with were utilized to assess the association between injury and AF/AFL. RESULTS: There were 130 reported AF/AFL cases, 90 of whom were injured and 40 were non-injured. The estimated cumulative incidence rates of AF/AFL for injured was higher compared to non-injured patients (hazards ratio [HR] = 2.04; 95% confidence interval [CI] = 1.44, 2.87). After adjustment demographics and tobacco use, the association did not appreciably decrease (HR = 1.90; 95% CI = 1.23, 2.93). Additional adjustment for obesity, hypertension, diabetes, and vascular disorders, the association between injury and AF/AFL was no longer statistically significant (HR = 1.51; 95% CI = 0.99, 2.52). CONCLUSION: Higher AF/AFL incidence rate was observed among deployed service members with combat injury compared to servicemembers without injury. The association did not remain significant after adjustment for cardiovascular-related covariates. These findings highlight the need for combat casualty surveillance to further understand the AF/AFL risk within the military population and to elucidate the potential underlying pathophysiologic mechanisms.

Psychological factors and cardiac repolarization instability during anger in implantable cardioverter defibrillator patients.

BACKGROUND: Evidence indicates that emotions such as anger are associated with increased incidence of sudden cardiac death, but the biological mechanisms remain unclear. We tested the hypothesis that, in patients with sudden death vulnerability, anger would be associated with arrhythmic vulnerability, indexed by cardiac repolarization instability. METHODS: Patients with coronary artery disease (CAD) and an implantable cardioverter defibrillator (ICD; n = 41) and healthy controls (n = 26) gave an anger-inducing speech (anger recall), rated their current (state) anger, and completed measures of trait (chronic) levels of Anger and Hostility. Repolarization instability was measured using QT Variability Index (QTVI) at resting baseline and during anger recall using continuous ECG. RESULTS: ICD patients had significantly higher QTVI at baseline and during anger recall compared with controls, indicating greater arrhythmic vulnerability overall. QTVI increased from baseline to anger recall to a similar extent in both groups. In ICD patients but not controls, during anger recall, self-rated anger was related to QTVI (r = .44, p = .007). Trait (chronic) Anger Expression (r = .26, p = .04), Anger Control (r = -.26, p = .04), and Hostility (r = .25, p = .05) were each associated with the change in QTVI from baseline to anger recall (ΔQTVI). Moderation analyses evaluated whether psychological trait associations with ΔQTVI were specific to the ICD group. Results indicated that Hostility scores predicted ΔQTVI from baseline to anger recall in ICD patients (ß = 0.07, p = .01), but not in controls. CONCLUSIONS: Anger increases repolarization lability, but in patients with CAD and arrhythmic vulnerability, chronic and acute anger interact to trigger cardiac repolarization lability associated with susceptibility to malignant arrhythmias.

Hemodynamic Effects of Late Sodium Current Inhibitors in a Swine Model of Heart Failure.

OBJECTIVES: To evaluate possible treatment-related hemodynamic changes, we administered ranolazine or mexiletine to swine with heart failure (HF) and to controls. BACKGROUND: Ranolazine and mexiletine potently inhibit depolarizing late Na+ current (INa,late) and Na+ entry into cardiomyocytes. Blocking Na+ entry may increase forward-mode Na/Ca exchange and reduce cellular Ca+2 load, further compromising systolic contraction during HF. METHODS AND RESULTS: Anesthetized tachypaced HF swine received ranolazine (n = 9) or mexiletine (n = 7) as boluses, then as infusions; the same experiments were performed in 10 nonpaced controls. The swine with HF had characteristic elevated left ventricular end-diastolic pressure (LVEDP) and reduced maximal left ventricular pressure rise (+dP/dtmax) and left ventricular peak systolic pressure (LVSP). No significant change occurred after ranolazine dosing for any parameter: LVEDP, +dP/dtmax, LVSP, heart rate, maximal LV pressure fall rate (-dP/dtmax), or time constant for isovolumic relaxation. Similar results seen in additional swine with HF: 7 were given mexiletine, and 7 others were given ranolazine after a 27% rate decrement to maximize INa,late. Patch-clamped HF cardiomyocytes confirmed drug-induced INa,late blockade. CONCLUSIONS: Ranolazine or mexiletine blocking INa,late neither worsened nor improved hemodynamics during advanced HF. Although results must be clinically confirmed, they suggest inhibition of INa,late by ranolazine or mexiletine may not exacerbate HF in patients.

Risk factors and the effect of cardiac resynchronization therapy on cardiac and non-cardiac mortality in MADIT-CRT.

AIMS: To understand modes of death and factors associated with the risk for cardiac and non-cardiac deaths in patients with cardiac resynchronization therapy with implantable cardioverter-defibrillator (CRT-D) vs. implantable cardioverter-defibrillator (ICD) therapy, which may help clarify the action and limitations of cardiac resynchronization therapy (CRT) in relieving myocardial dysfunction. METHODS AND RESULTS: In Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT), during 4 years of follow-up, 169 (9.3%) of 1820 patients died of known causes, 108 (63.9%) deemed cardiac, and 61 (36.1%) non-cardiac. In multivariate analysis, increased baseline creatinine was significantly associated with both cardiac and non-cardiac deaths [hazard ratio (HR) 2.97, P < 0.001; HR 1.80, P = 0.035, respectively], as was diabetes (HR 1.79, P = 0.006; HR 1.73, P = 0.038, respectively), and the worst New York Heart Association Class > II more than 3 months prior to enrolment (HR 1.90, P = 0.012; HR 2.46, P = 0.010, respectively). Baseline left atrial volume index was significantly associated only with cardiac mortality (HR 1.28 per 5 unit increase, P < 0.001). Ischaemic cardiomyopathy was associated only with non-cardiac death (HR 3.54, P = 0.001). CRT-D vs. an ICD-only was associated with a reduced risk for cardiac death in patients with left bundle branch block (LBBB) (HR 0.56, P = 0.029) but was associated with an increased risk for non-cardiac death in non-LBBB patients (HR 3.48, P = 0.048). CONCLUSIONS: In MADIT-CRT, two-thirds of the deaths were cardiac and one-third non-cardiac. Many of the same risk factors were associated with both cardiac and non-cardiac mortalities. CRT-D was associated with a reduced risk for cardiac death in LBBB but an increased risk for non-cardiac death in non-LBBB. CLINICAL TRIAL REGISTRATION: Information for the MADIT-CRT main study http://www.clinicaltrials.gov, NCT00180271.

Ranolazine for the suppression of ventricular arrhythmia: a case series.

BACKGROUND: Premature ventricular complexes (PVCs) and ventricular tachycardia (VT) are associated with persistent symptoms and ventricular dysfunction. Approved medical therapies have undesirable side effects and proarrhythmic liability. Ranolazine is a novel antianginal that preferentially blocks the late sodium current. This current is enhanced among patients with cardiomyopathy; a promising target population for ranolazine. The utility of ranolazine, however, for ventricular arrhythmia suppression has not been well characterized. OBJECTIVES: We sought to determine the effectiveness of ranolazine for suppression of ventricular ectopy, particularly in the setting of ventricular dysfunction where enhanced efficacy might be expected. METHODS: We retrospectively evaluated eight patients (six with >10% PVC burden and two with incessant VT) treated with ranolazine. Arrhythmia frequency was evaluated by continuous monitoring before and after ranolazine initiation and the correlation between ventricular function and reduction in PVC burden was assessed. RESULTS: Among six patients with PVCs, ranolazine resulted in a median decrease in PVC burden of 60.2% (P = 0.06). In two cases of apparent PVC-induced cardiomyopathy, normalization of ventricular function was observed. A significant, inverse correlation between baseline ejection fraction and percentage reduction in PVCs was observed (rho = -0.89, P = 0.02). In two patients treated for incessant VT despite Class III antiarrhythmic therapy, ranolazine eliminated VT and prevented recurrent defibrillator therapy. CONCLUSIONS: Although not approved for this indication, ranolazine appears effective for symptomatic ventricular arrhythmias. The reduction in PVC burden was greatest among individuals with reduced ventricular function, perhaps due to enhanced late sodium current associated with cardiomyopathy. A confirmatory prospective trial seems warranted.

Sleep-Disordered Breathing Destabilizes Ventricular Repolarization.

Rationale: Sleep-disordered breathing (SDB) increases the risk of cardiac arrhythmias and sudden cardiac death. Objectives: To characterize the associations between SDB, intermittent hypoxemia, and the beat-to-beat QT variability index (QTVI), a measure of ventricular repolarization lability associated with a higher risk for cardiac arrhythmias, sudden cardiac death, and mortality. Methods: Three distinct cohorts were used for the current study. The first cohort, used for cross-sectional analysis, was a matched sample of 122 participants with and without severe SDB. The second cohort, used for longitudinal analysis, consisted of a matched sample of 52 participants with and without incident SDB. The cross-sectional and longitudinal cohorts were selected from the Sleep Heart Health Study participants. The third cohort comprised 19 healthy adults exposed to acute intermittent hypoxia and ambient air on two separate days. Electrocardiographic measures were calculated from one-lead electrocardiograms. Results: Compared to those without SDB, participants with severe SDB had greater QTVI (-1.19 in participants with severe SDB vs. -1.43 in participants without SDB, P = 0.027), heart rate (68.34 vs. 64.92 beats/minute; P = 0.028), and hypoxemia burden during sleep as assessed by the total sleep time with oxygen saturation less than 90% (TST90; 11.39% vs. 1.32%, P < 0.001). TST90, but not the frequency of arousals, was a predictor of QTVI. QTVI during sleep was predictive of all-cause mortality. With incident SDB, mean QTVI increased from -1.23 to -0.86 over 5 years (P = 0.017). Finally, exposing healthy adults to acute intermittent hypoxia for four hours progressively increased QTVI (from -1.85 at baseline to 1.64 after four hours of intermittent hypoxia; P = 0.016). Conclusions: Prevalent and incident SDB are associated with ventricular repolarization instability, which predisposes to ventricular arrhythmias and sudden cardiac death. Intermittent hypoxemia destabilizes ventricular repolarization and may contribute to increased mortality in SDB.

The Tactical Athlete: Definitions, Cardiovascular Assessment, and Management, and "Fit for Duty" Standards.

Tactical athletes are individuals in the military, law enforcement, and other professions whose occupations have significant physical fitness requirements coupled with the potential for exposure to life-threatening situations. Such exposures can have varied hemodynamic effects on the cardiovascular system. It is crucial that their clinical evaluation is inclusive of specific occupational requirements. Safety protocols regarding medical clearance are relatively more stringent for this population than for competitive athletes due to the increased impact to the tactical athlete, their team, and the population they aim to serve and protect should they experience a cardiovascular event on the job.

Case report: Antidromic atrioventricular reentrant tachycardia and underlying Ebstein anomaly.

Multiple accessory pathways (APs) can develop in patients with Ebstein anomaly. Rarely, these APs can participate in antidromic atrioventricular reentrant tachycardia (AVRT) which can be life-threatening and requires unique considerations for acute management and ultimate ablation. These considerations are discussed herein.

Multiacquisition T1-mapping MRI during tidal respiration for quantification of myocardial T1 in swine with heart failure.

OBJECTIVE: The purpose of this article is to evaluate a free-breathing pulse sequence to quantify myocardial T1 changes in a swine model of tachycardia-induced heart failure. MATERIALS AND METHODS: Yorkshire swine were implanted with pacemakers and were ventricularly paced at 200 beats/min to induce heart failure. Animals were scanned twice with a 1.5-T MRI scanner, once at baseline and once at heart failure. A T1-mapping sequence was performed during tidal respiration before and 5 minutes after the administration of a gadolinium-chelate contrast agent. T1-mapping values were compared between the baseline and heart failure scans. The percentage of fibrosis of heart failure myocardial tissue was compared with similar left ventricular tissue from control animals using trichrome blue histologic analysis. RESULTS: In the study cohort, differences were found between the baseline and heart failure T1-mapping values before the administration of contrast agent (960 ± 96 and 726 ± 94 ms, respectively; p = 0.02) and after contrast agent administration (546 ± 180 and 300 ± 171 ms, respectively; p = 0.005). The animals with heart failure also had a difference histologically in the percentage of myocardial collagen compared with tissue from healthy control animals (control, 5.4% ± 1.0%; heart failure, 9.4% ± 1.6%; p < 0.001). CONCLUSION: The proposed T1-mapping technique can quantify diffuse myocardial changes associated with heart failure without the use of a contrast agent and without breath-holding. These T1 changes appear to be associated with increases in the percentage of myocardial collagen that in this study were not detected by traditional myocardial delayed enhancement imaging. T1 mapping may be a useful technique for detecting early but clinically significant myocardial fibrosis.

The Tactical Athlete: Definitions, Cardiovascular Assessment, and Management, and "Fit for Duty" Standards.

Tactical athletes are individuals in the military, law enforcement, and other professions whose occupations have significant physical fitness requirements coupled with the potential for exposure to life-threatening situations. Such exposures can have varied hemodynamic effects on the cardiovascular system. It is crucial that their clinical evaluation is inclusive of specific occupational requirements. Safety protocols regarding medical clearance are relatively more stringent for this population than for competitive athletes due to the increased impact to the tactical athlete, their team, and the population they aim to serve and protect should they experience a cardiovascular event on the job.

Prevalence of Heart Failure Stages in a Universal Health Care System: The Military Health System Experience.

BACKGROUND: Morbidity and mortality related to heart failure are increasing and disparities are widening. These alarming trends, often confounded by access to care, are poorly understood. This study evaluates the prevalence of all stages of heart failure by race and socioeconomic status in an environment with no access barrier to care. METHODS: We conducted a cross-sectional observational study of adult beneficiaries aged 18 to 64 years of the Military Health System (MHS), a model for universal health care for fiscal years 2018-2019. We calculated prevalence of preclinical (stages A/B) or clinical (stages C/D) heart failure stages as defined by professional guidelines. Results were analyzed by age, race, and socioeconomic status (using military rank as a proxy). RESULTS: Among 5,440,761 MHS beneficiaries aged 18 to 64 years, prevalence of preclinical and clinical heart failure was 18.1% and 2.5%, respectively. Persons with preclinical heart failure were middle aged, with similar proportions of men and women, while those with heart failure were older, mainly men. After multivariable adjustment, male sex (1.35 odds ratio [OR] [preclinical]; 1.95 OR [clinical]), Black race (1.64 OR [preclinical]; 1.88 OR [clinical]) and lower socioeconomic status were significantly associated with large increases in the prevalence of all stages of heart failure. CONCLUSION: All stages of heart failure are highly prevalent among MHS beneficiaries of working age and, in an environment with no access barrier to care, there are striking disparities by race and socioeconomic status. The high prevalence of preclinical heart failure, particularly notable among Black beneficiaries, delineates a critical time window for prevention.

Ventricular Arrhythmias Associated With Over-the-Counter and Recreational Opioids.

BACKGROUND: Epidemic increases in opioid deaths prompted policies limiting access to prescription opioids in North America. Consequently, the over-the-counter opioids loperamide (Imodium A-D) and mitragynine, the herbal ingredient in kratom, are increasingly used to avert withdrawal or induce euphoria. Arrhythmia events related to these nonscheduled drugs have not been systematically studied. OBJECTIVES: In this study, we sought to explore opioid-associated arrhythmia reporting in North America. METHODS: The U.S. Food and Drug Administration Adverse Event Reporting System (FAERS), Center for Food Safety and Applied Nutrition Adverse Event Reporting System (CAERS), and Canada Vigilance Adverse Reaction (CVAR) databases were searched (2015-2021). Reports involving nonprescription drugs (loperamide, mitragynine) and diphenoxylate/atropine (Lomotil) were identified. Methadone, a prescription opioid (full agonist), served as a positive control owing to its established arrhythmia risk. Buprenorphine (partial agonist) and naltrexone (pure antagonist), served as negative controls. Reports were classified according to Medical Dictionary for Regulatory Activities terminology. Significant disproportionate reporting required a proportional reporting ratio (PRR) of ≥2, ≥3 cases, and chi-square ≥4. Primary analysis used FAERS data, whereas CAERS and CVAR data were confirmatory. RESULTS: Methadone was disproportionately associated with ventricular arrhythmia reports (PRR: 6.6; 95% CI: 6.2-7.0; n = 1,163; chi-square = 5,456), including 852 (73%) fatalities. Loperamide was also significantly associated with arrhythmia (PRR: 3.2; 95% CI: 3.0-3.4; n = 1,008; chi-square = 1,537), including 371 (37%) deaths. Mitragynine demonstrated the highest signal (PRR: 8.9; 95% CI: 6.7-11.7; n = 46; chi-square = 315), with 42 (91%) deaths. Buprenorphine, diphenoxylate, and naltrexone were not associated with arrhythmia. Signals were similar in CVAR and CAERS. CONCLUSIONS: The nonprescription drugs loperamide and mitragynine are associated with disproportionate reports of life-threatening ventricular arrhythmia in North America.

Loss of control eating in relation to blood pressure among adolescent girls with elevated anxiety at-risk for excess weight gain.

Loss of control (LOC)-eating, excess weight, and anxiety are robustly linked, and are independently associated with markers of poorer cardiometabolic health, including hypertension. However, no study has examined whether frequency of LOC-eating episodes among youth with anxiety symptoms and elevated weight status may confer increased risk for hypertension. We examined the relationship between LOC-eating frequency and blood pressure among 39 adolescent girls (14.9 ± 1.8 years; body mass index [BMI] = 29.9 ± 5.6; 61.5 % White; 20.5 % African American/Black; 5 % Multiple Races; 2.5 % Asian; 12.8 % Hispanic/Latino; 30.8 % with reported LOC-eating) with elevated anxiety and above average BMI who enrolled in a clinical trial aimed at preventing excess weight gain. LOC-eating over the past three months was assessed via clinical interview, and blood pressure (systolic and diastolic) was measured with an automatic blood pressure monitor. Adjusting for age, fat mass, and height, LOC-eating episode frequency was significantly, positively associated with diastolic blood pressure (ß = 0.38, p = 0.02), but not with systolic blood pressure (ß = 0.13, p = 0.41). Replication studies, with larger sample sizes, participants of varying weight-strata, and prospective data are required to elucidate the relationship between LOC-eating and cardiovascular functioning in youth with elevated anxiety.

The clinical significance of QT interval prolongation in anesthesia and pain management: what you should and should not worry about.

The most feared drug-induced complication is fatal cardiac arrest. Torsades de pointes (TdP) is a polymorphic ventricular tachycardia occurring in the setting of a QT interval prolongation and is the most frequent type of drug-induced pro-arrhythmia. The most common mechanism of QT prolongation and TdP is blockade of the rapid component of the delayed rectifier repolarizing potassium conductance IKr. Anesthesiologists have extensive experience with QT prolonging drugs, but there are relatively few reports of TdP occurring in the perioperative setting. Nevertheless, regulatory concern regarding the drug droperidol resulted in a significant reduction in its use. Concern regarding two other agents that potently block IKr, i.e., sevoflurane and methadone, has grown, and practitioners are worried that these valuable agents may meet the same fate. In this review, the data regarding the TdP risk of droperidol, sevoflurane, and methadone are compared with particular emphasis on the different settings in which they are employed. While the three drugs are potent IKr inhibitors, little evidence exists to suggest that droperidol or sevoflurane are associated with significant proarrhythmia in the perioperative setting. Due to factors such as inhibition of the parasympathetic nervous system, prevention of hypoxia and hypercarbia, and attention to serum electrolytes, TdP is a very rare occurrence in the perioperative environment. Methadone, however, is typically given to outpatients, over long periods, and in combination with agents that inhibit its metabolism or are QT prolonging in their own right. Thus, pre- and post-drug electrocardiograms may be appropriate when prescribing methadone for outpatients, while the much lower risk for TdP (and the difficulties inherent in QT measurement in the perioperative period) render this approach unfruitful and worthy of reevaluation.

Cardiac electrophysiology and the athlete: a primer for the sports clinician.

Intense exercise requires a significant increase in cardiac output in order to meet the needs of the skeletal muscles for oxygenated blood. In order to improve cardiac performance, the autonomic nervous system increases sympathetic tone primarily through release of norepinephrine from postganglionic receptors to stimulate the ß-adrenergic receptors of the nodal and muscle tissue of the heart. This event initiates a signaling cascade focused on increasing the amount of calcium available to the contractile myofilaments in the cardiac cell. Failure of the myocytes to counterbalance the increase in inward ion flow or adequately sequester cytosolic calcium during diastole leads to potentially catastrophic electrical instability. In this review, the relationship between the cellular events initiated by exercise and the induction of arrhythmias associated with the long QT, Brugada, and Wolff-Parkinson-White syndromes; catecholaminergic polymorphic ventricular tachycardia; and the heritable cardiomyopathies are explored.