Dysrhythmic Events Research Articles

Incidence of Persistent Left Bundle Branch Block After Rapid-Deployment Aortic Valve Replacement

BackgroundWe evaluated the incidence, prognosis, and predictive factors of new onset of persistent left bundle branch block (NOP-LBBB) after rapid-deployment aortic valve replacement (RD-AVR). MethodsThis was an observational, retrospective, single-center study of 274 consecutive patients with no baseline ventricular conduction disorder and no previous permanent pacemaker implantation (PPI) who underwent RD-AVR with an INTUITY valve (n = 55) or INTUITY Elite Valve (n = 219) (Edwards Lifesciences). Transthoracic echocardiography and 12-lead electrocardiography was performed preoperatively, at discharge, and at 1-month and 1-year intervals. The incidence, prognosis, and predictive factors of NOP-LBBB were evaluated. ResultsNOP-LBBB occurred in 58 patients (21.2%) after discharge. In multivariate analysis, age (P < .01), INTUITY valve diameter ≥23 mm (P = .02), and INTUITY Elite implantation (P = .01) were independent predictors of NOP-LBBB. By 1:1 propensity matching analysis between the NOP-LBBB group and the control group, there were no significant differences in 1-year overall mortality (P = .23), hospitalization for congestive heart failure (P = .99), or PPI (P = .99). NOP-LBBB exposed patients to a high rate of dysrhythmic events (12.1% vs 1.4%, P < .01) and was associated with a significant decrease in left ventricular ejection fraction (0.62 ± 0.095 vs 0.652 ± 0.0783, P = .02) without an impact on New York Heart Association functional status (1.25 ± 0.32 and 1.52 ± 0.70, P = .32). PPI was performed in 17 patients (6.2%) before discharge, including 14 NOP-LBBB patients. ConclusionsNOP-LBBB after RD-AVR is prevalent in patients with no prior conduction disorders. INTUITY Elite is associated with a significantly higher rate of NOP-LBBB. The persistence of NOP-LBBB predisposed patients to the occurrence of high-grade conduction disorders and might have led to PPI but did not increase death or hospitalization for congestive heart failure.

Hypertrophic cardiomyopathy: CMR to predict dysrhythmic events

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In hypertrophic cardiomyopathy (HCM), there is a significant contribute of dysrhythmic events (DE) for the burden of morbidity and mortality of the disease. The aim of this study is to assess the arrhythmic profile of HCM patients (pts) and predictors of DE. Methods Retrospective single-center study of consecutive pts with HCM defined by wall thickness ≥15 mm in ≥1 LV myocardial segments in CMR; pts with history of uncontrolled hypertension (HTN) and significant valvular disease were excluded. Demographic, clinical, CMR data and outcomes were analyzed. For statistical analysis, chi-square and Mann-Whitney tests were used, with prediction of DE (atrial fibrillation (AF); ventricular tachycardia (VT)) and implantation of cardioverter defibrillator (ICD)) with binary logistic regression model. Results We included 36 pts, aged 62.5 year-old (IQR: 49,5-74,8), 64% male. 69% had controlled HTN, 46% dyslipidemia and 23% diabetes; family history (FH) of sudden cardiac death and HCM occurred in 16% and 46%, respectively. 9% presented with syncope, 21% with palpitations and 12% with angina. Previous history of AF was present in 12% pts. 42% pts had genetic study and mutations were identified in 25% (TNNT2: 8,3%; MYBPC3:5.6%). All were in sinus rhythm at baseline. On ECG, intraventricular disturbance conduction was found in 33% and T wave inversion in 39%. On CMR, most pts had septal wall hypertrophy(81%), while 11% had apical, 3% anterior-wall and 6% lateral-wall. SAM was present in 28% and LVOTO in 33%. 69% of the pts had LGE (midwall: 61%, subendocardial: 11%, subepicardial: 3%, at hypertrophic segments: 47%, RV/LV insertion points: 25%, other: 19.4%). During a mean follow-up of 496 ± 338 days, new onset of AF was found in 26%, VT episodes in 20%, ICD implantation in 29% and 3% died. There were no associations of clinical data and AF. In univariate analysis, SAM (OR 5.25, CI95% 1.02-26.9, p = 0.047), LVOTO (OR 6.7, CI95% 1.27-35.0, p = 0.025), distribution of LGE on other segments than RV/LV insertion points (OR 9.6, CI95% 1.36-67.6, p = 0.023) and absence of T-wave inversion (OR 0.17, CI95% 0.033-0.937, p = 0.042), predicted AF. The absence of T-wave inversion was the only independent predictor of AF in our population (OR 0.073, CI95% 0.006-0.949, p = 0.045).There were no independent predictors of ventricular arrythmias. Also, we found that AF predicted VT (OR 6.13, CI95% 1.032-36.45, p = 0.046) in univariate analysis and was an independent predictor for ICD (OR 9.6, CI95% 1.26-67.59, p = 0.023). AF was a predictor of composite outcome (death, heart failure and thromboembolic events) in our population (OR 6.3 CI95% 1.3-31.1, p = 0.024). Conclusion In our population, T-wave changes, SAM, LVOTO and LGE distribution were predictors of AF, which was an independent predictor for ICD implantation. No predictors for ventricular arrhythmias were found. Larger studies taking into account echo and CMR data should be conducted to confirm these findings.

Pulseless Electrical Activity: Echocardiographic Explanation of a Perplexing Phenomenon.

Pulseless electrical activity (PEA) is considered an enigmatic phenomenon in resuscitation research and practice. Finding individuals with no consciousness or pulse but with continued electrocardiographic (EKG) complexes obviously raises the question of how they got there. The development of monitors that can display the underlying rhythm has allowed us to differentiate between VF, asystole, and PEA. Lack of clear understanding of the emergence of PEA has limited the research and development of interventions that might improve the low rates of survival typically associated with PEA. Over 30 years of studying and practicing resuscitation have allowed the authors to see a substantial rise in PEA with variable survival rates, based on the patients' illness spectrum and intensity of monitoring. This paper presents a small case series of individuals with brain death whose family members consented to the echocardiographic observation of the dying process after disconnection from life support. The observation from these cases confirms that PEA is a late phase in the clinical dying process. Echocardiographic images delineate the stages of pseudo-PEA with ineffective contractions, PEA, and then asystole. The process is contiuous with none of the sudden phase shifts seen in dysrhythmic events such as VF, VT or SVT. The implications of these findings are that PEA is a common manifestation of tissue hypoxia and metabolic substrate depletion. Our findings offer prospects for studies of the development of interventions to improve PEA survival.

Is Insulin Therapy Safe?

After 98 years of insulin therapy, issues of safety remain of concern. Uncertainty has been expressed variously in regard of arterial cell wall proliferation, promotion of proliferative retinopathy, promotion of tumor growth, and for pregnancy. Immunological issues have been little studied since the advent of highly purified insulins in the 1970s. A specific topic is whether hypoglycemia, severe or otherwise, might promote cardiac thrombotic or dysrhythmic events. A literature review in these areas is difficult because nearly all clinical trials with insulin refer to adverse events. However, the specific topics aforementioned allow for some informed literature searching supplemented by finger-searching of published articles, notably in connection with the insulin analogues. Safety data for pregnancy are weak because of power problems, but there are no signals for added maternal or fetal risk. Clinical-outcome trials that assess insulin against other glucose-lowering therapies or with significantly different insulin preparations in different arms are few and are sometimes conducted at modest dosage but fail to suggest promotion of arterial disease. Concern over growth-promoting activity of insulin glargine turned out to be ill-founded when the circulating moiety after injection was noted to have a lower IGF-1:insulin activity than human insulin, and a direct study of retinopathy progression or meta-analysis of malignancy incidence failed to show signals of concern. It does seem that severe hypoglycemia can cause death in some people with type 1 diabetes, although the tissue mechanism is unknown, but reducing severe hypoglycemia in type 2 diabetes does not protect against arterial events. Both symptomatic and severe hypoglycemia can however be reduced by use of more recently marketed insulin analogues, and this improves tolerability if not safety. In conclusion, although insulin therapy clearly gives health benefits, the evidence for long-term harm is absent or weak.

Epinephrine Administered for Anaphylaxis Unmasking a Type 1 Brugada Pattern on Electrocardiogram.

Brugada pattern on electrocardiography (ECG) can manifest as type 1 (coved pattern) and type 2 (saddleback pattern). Brugada syndrome represents an ECG with Brugada pattern in a patient with symptoms or clinical factors, including syncope, cardiac arrest, ventricular dysrhythmias, and family history. Brugada syndrome is caused by a genetic channelopathy, but the Brugada pattern may be drug-induced. Epinephrine-induced Brugada pattern has not been reported previously. A 63-year-old man developed anaphylaxis secondary to a bee sting, had a transient loss of consciousness, and self-administered intramuscular epinephrine. He subsequently presented to the emergency department and was found to have a type 1 Brugada pattern on ECG that resolved during observation. A historic ECG was reviewed that demonstrated a baseline type 2 Brugada pattern. His anaphylaxis was managed with steroids and antihistamines. He was observed without subsequent dysrhythmic events on telemetry or any further symptoms. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The differential diagnosis for syncope includes dysrhythmia, such as Brugada syndrome. Among other possible drugs, epinephrine may induce a type 1 Brugada pattern. Patients with Brugada pattern on ECG should be referred immediately to electrophysiology for consideration of implantation of a cardioverter-defibrillator device, given the association of Brugada pattern with sudden cardiac arrest and ventricular dysrhythmias.

P305Unsafe drugs use and dysrhythmic events in Brugada patients with ICD: results of a long-term follow-up

P305Unsafe drugs use and dysrhythmic events in Brugada patients with ICD: results of a long-term follow-up

Acquired prolongation of QT interval as a risk factor for torsade de pointes ventricular tachycardia: a narrative review for the anesthesiologist and intensivist.

More than 70% of intensive care unit (ICU) patients experience heart rhythm disturbances, and these patients have correspondingly higher mortality rates. Consequently, one of the standards of care in ICUs is continuous electrocardiography monitoring. One of the potentially preventable dysrhythmic events is the occurrence of torsade de pointes ventricular tachycardia in the setting of acquired prolonged QT interval. This type of ventricular tachycardia can be malignant because it often progresses to ventricular fibrillation. Many factors predispose to lengthening of the QT interval, the most important of which are electrolyte abnormalities and the administration of specific medications. In this review, we discuss the pathophysiology of acquired long QT interval, stressing the medication-induced acquired long QT-interval and factors present in ICU patients that promote prolongation of the QT interval. We also propose guidelines to avoid the occurrence of torsade de pointes ventricular tachycardia.

Simultaneous anterior and posterior serosal mapping of gastric slow-wave dysrhythmias induced by vasopressin.

What is the central question of this study? This study aimed to provide the first comparison of simultaneous high-resolution mapping of anterior and posterior gastric serosa over sustained periods. What is the main finding and its importance? Episodes of spontaneous gastric slow-wave dysrhythmias increased significantly following intravenous infusion of vasopressin compared with the baseline state. A number of persistent dysrhythmias were defined, including ectopic activation, conduction block, rotor, retrograde and collision/merger of wavefronts. Slow-wave dysrhythmias could occur either simultaneously or independently on the anterior and posterior gastric serosa, and interacted depending on activation-repolarization and frequency dynamics. High-resolution mapping enables mechanistic insights into gastric slow-wave dysrhythmias and is now achieving clinical translation. However, previous studies have focused mainly on dysrhythmias occurring on the anterior gastric wall. The present study simultaneously mapped the anterior and posterior gastric serosa during episodes of dysrhythmias induced by vasopressin to aid understanding of dysrhythmia initiation, maintenance and termination. High-resolution mapping (8×16 electrodes on each serosa; 20-74cm2 ) was performed in anaesthetized dogs. Baseline recordings (21±8min) were followed by intravenous infusion of vasopressin (0.1-0.5IUml-1 at 60-190mlh-1 ) and further recordings (22±13min). Slow-wave activation maps, amplitudes, velocity, interval and frequency were calculated, and differences compared between baseline and postinfusion. All dogs demonstrated an increased prevalence of dysrhythmic events following infusion of vasopressin (17 versus 51%). Both amplitude and velocity demonstrated significant differences (baseline versus postinfusion: 3.6versus 2.2mV; 7.7versus 6.5mm s-1 ; P<0.05 for both). Dysrhythmias occurred simultaneously or independently on the anterior and posterior serosa, and then interacted according to frequency dynamics. A number of persistent dysrhythmias were compared, including the following: ectopic activation (n=2 animals), conduction block (n=1), rotor (n=2), retrograde (n=3) and collision/merger of wavefronts (n=2). We conclude that infusion of vasopressin induces gastric dysrhythmias, which occur across a heterogeneous range of frequencies and patterns. The results demonstrate that different classes of gastric dysrhythmias may arise simultaneously or independently in one or both surfaces of the serosa, then interact according to their relative frequencies. These results will help to inform interpretation of clinical dysrhythmia.

Iterative Covariance-Based Removal of Time-Synchronous Artifacts: Application to Gastrointestinal Electrical Recordings.

The aim of this study was to develop, validate, and apply a fully automated method for reducing large temporally synchronous artifacts present in electrical recordings made from the gastrointestinal (GI) serosa, which are problematic for properly assessing slow wave dynamics. Such artifacts routinely arise in experimental and clinical settings from motion, switching behavior of medical instruments, or electrode array manipulation. A novel iterative Covariance-Based Reduction of Artifacts (COBRA) algorithm sequentially reduced artifact waveforms using an updating across-channel median as a noise template, scaled and subtracted from each channel based on their covariance. Application of COBRA substantially increased the signal-to-artifact ratio (12.8 ± 2.5 dB), while minimally attenuating the energy of the underlying source signal by 7.9% on average ( -11.1 ± 3.9 dB). COBRA was shown to be highly effective for aiding recovery and accurate marking of slow wave events (sensitivity = 0.90 ± 0.04; positive-predictive value = 0.74 ± 0.08) from large segments of in vivo porcine GI electrical mapping data that would otherwise be lost due to a broad range of contaminating artifact waveforms. Strongly reducing artifacts with COBRA ultimately allowed for rapid production of accurate isochronal activation maps detailing the dynamics of slow wave propagation in the porcine intestine. Such mapping studies can help characterize differences between normal and dysrhythmic events, which have been associated with GI abnormalities, such as intestinal ischemia and gastroparesis. The COBRA method may be generally applicable for removing temporally synchronous artifacts in other biosignal processing domains.

A Case of 5-Fluorouracil-Induced Cardiac Arrest

BackgroundCoronary artery vasospasm after administration of fluorouracil (5-FU) is a rare complication. Commonly presenting as chest pain during or shortly after 5-FU infusions, vasospasm can place patients at risk for ventricular dysrhythmia, myocardial ischemia, and infarction. Although not fully understood, any 5-FU cardiotoxicity seems to be multifactorial, and patients with coronary artery disease and renal dysfunction may be at particular risk. Case ReportA 46-year-old woman with no prior cardiovascular disease history presented with sudden-onset chest pain after initial administration of 5-FU continuous infusion therapy. The patient subsequently developed ventricular fibrillation arrest and underwent successful electrocardioversion. Coronary angiography was unremarkable for coronary stenosis or vasospasm. The presumed etiology was secondary to 5-FU cardiac toxicity. The patient was re-challenged with 5-FU therapy and developed repeat chest pain. The 5-FU was completely stopped and the patient's symptoms resolved, with no further dysrhythmic events 9 months after initial presentation. Why Should an Emergency Physician Be Aware of This?Patients who develop chest pain during or after 5-FU infusion should warrant strong consideration for admission and continuous cardiac monitoring for potential ventricular dysrhythmias and cardiac ischemia.

Acute effect of zoledronic acid on the risk of cardiac dysrhythmias.

There have been recent concerns regarding the risk of serious adverse events, such as cardiac dysrhythmia and atrial fibrillation (AF), associated with bisphosphonate use in osteoporosis. This open-label, non-randomized, crossover pilot study evaluated short-term effects of zoledronic acid and placebo on the occurrence of cardiac dysrhythmias and prodysrhythmic profile in postmenopausal women with osteoporosis and low risk of cardiac dysrhythmias. Fifteen postmenopausal women (mean age 70.7 ± 6.9 years) with osteoporosis received placebo infusion on day 1 and zoledronic acid 5 mg on day 7. Standard 12-lead resting EKG measured QT parameters at baseline and up to 24 h after infusion. Continuous 24-h EKG assessed dysrhythmic events and heart rate variability (HRV) for 24 h after infusion. There were no statistically significant differences in resting EKG parameters between placebo and zoledronic acid: QTc (404.28 ± 9.28 and 410.63 ± 18.43 ms), no significant differences in mean serum electrolytes at baseline and after infusion, and no significant association between QT/QTc parameters and serum electrolytes before and after each infusion (QTc: 401.83 ± 17.73 for zoledronic acid and 404.65 ± 16.79 for placebo). There was no significant difference in HRV parameters between placebo and zoledronic acid, and no dysrhythmias were recorded at rest or with 24 h EKG monitoring. Zoledronic acid does not produce dysrhythmia or prodysrhythmic effects in the short term. Among possible mechanisms proposed for cardiac dysrhythmias with zoledronic acid, no serum electrolyte or autonomous nervous system balance perturbations have been reported.

Risk of Fatal Dysrhythmic Events in Long QT Syndrome Patients After Syncope

In this retrospective observational study of 1059 patients from the International Long QT Syndrome (LQTS) Registry, the authors analyzed risk factors for sudden cardiac death (SCD) and severe dysrhythmic events (SDE) in a database of patients with LQTS. The study group included 1059 LQTS registry patients from 764 families with corrected QT interval (QTc) of ≥ 450 milliseconds (ms). In these patients, beta-blocker therapy was initiated at the discretion of the patient's physician. The primary endpoint was SDE or SCD.

Empirical-Bayes adjustment improved conventional estimates in postmarketing drug-safety studies

Objectives Empirical-Bayes adjustment was used to investigate the effects of antibacterials on risk of arrhythmia in a large cohort study based upon automated record linkage. Study Design and Setting The Prescription Drug Database of the Varese Province, Italy, was used to form a population-based cohort of patients who received at least one prescription of antibacterials for systemic use. All cohort members were followed-up from the beginning of each antibacterial therapeutic cycle up to 60 days afterward, identifying the first prescription of an antiarrhythmic drug and/or the first admission for arrhythmia. Standardized incidence ratios for eight classes of antibacterials, as well as for the specific antibacterial drugs, were estimated using both conventional methods and empirical-Bayes (EB) adjustment. Results Using EB adjustment, overall precision was greatly enhanced compared to the conventional analysis. Statistical evidence of drug-induced dysrhythmic events was found for 17 drugs mostly belonging to Macrolides and Quinolones. Strongest proarrhythmic effects were found for Ciprofloxacin (standardized incidence ratio [SIR]: 1.98; 95% CI: 1.67, 2.34) and Erythromycin (SIR: 1.91; 95% CI: 1.20, 2.88). Conclusion Empirical-Bayes may mitigate some problems inherent the conventional analysis. Macrolides and Quinolones were associated with the highest number of positive signals of dysrhythmic events. This requires further investigation by other types of epidemiologic studies.

Estimating Gastric Rhythm Differences Using a Wavelet Method from the Electrogastrograms of Normal and Diabetic Subjects

Electrogastrogram (EGG) is the cutaneous recording of gastric electrical activity. Some patients with nausea, vomiting, early satiety, and patients with long term insulin‐dependent diabetes exhibit gastric electrical rhythm disturbances. We are interested in investigating the EGG to determine if abnormalities of the EGG occur in association with those gastric complaints. The aim of this document is to investigate long term diabetics with a history of such gastric dysrhythmia complaints in an effort to further characterize the frequency of abnormalities of the EGG in real clinical diabetic gastroparesis patients. For feature extraction purposes, we have performed Wavelet‐Packet analysis of EGG signals and have obtained power spectral density of wavelet‐packet details and approximation coefficients in diabetic patients suffering from gastric dysrhythmia (tachygastria, bradygastria) and healthy volunteers. Wavelet‐Packet analysis provides details of changes in frequency components at any time point, and enhanced interpretation of cutaneous EGG recordings. In conclusion, this paper has shown that the Wavelet‐Packet analysis method is very useful in the analysis of cutaneous EGG recordings, especially in detecting dysrhythmic events.

Alcohol Use, Misuse, Abuse, and Dependence in Later Adulthood

Considerable research has focused on alcohol problems in older adults, but the clinical utilization of this knowledge has lagged at least 3 decades behind the scientific developments. This unfortunate situation takes on added significance as the "baby boomer" generation ages because more of them drink more often in larger quantities than previous generations. This chapter focuses more on the ramifications of use, misuse, and abuse than on chronic dependence because the prevalence in the former categories far outweighs the latter. Older alcohol misusers and abusers are at excess risk for myriad physical problems and premature death because alcohol interacts with the natural aging process in negative ways to increase risks for injuries, hypertension, cardiac dysrhythmic events, cancers, gastrointestinal problems, neurocognitive deficits, bone loss, and emotional challenges, most notably depression. Low volume and less than daily alcohol consumption appear to be protective against blood clots in the coronary and brain vessels, bone loss and falls, and cognitive decline compared with current abstainers. At higher levels, alcohol has the opposite effect. Research findings strongly support positive outcomes of case finding, referral, and treatment of older adults who are misusing or abusing alcohol. However, there is ample evidence that health care providers across the spectrum of primary, acute, and long-term care ignore the signs and symptoms of alcohol misuse and abuse in their older patients and treat symptoms and sequelae of the abuse rather than confronting the abuse itself. Recommendations for changes in practice are made together with ideas for additional research in several areas where the current state of knowledge is inadequate, conflicting, or based on narrowly homogeneous samples.

Profiles of hepatic and dysrhythmic cardiovascular events following use of fluoroquinolone antibacterials: experience from large cohorts from the Drug Safety Research Unit Prescription-Event Monitoring database.

To investigate how frequently serious dysrhythmic cardiovascular, and hepatotoxic events are reported during routine clinical use of fluoroquinolones (quinolones) in general practice. Cohorts prescribed quinolones (cohort sizes: ciprofloxacin 11 477; enoxacin 2790; ofloxacin 11 033 and norfloxacin 11 110; mean age in each cohort of 48.6 to 57.0 years) were selected from the Drug Safety Research Unit's Prescription-Event Monitoring (PEM) database. The monitoring periods were November 1988 to January 1989 for ciprofloxacin; April 1989 to January 1991 for enoxacin; May 1991 to December 1991 for ofloxacin and October 1990 to October 1991 for norfloxacin. Data collected over the total PEM surveillance period on selected gastrointestinal events were extracted and reviewed to identify possible hepatic events, together with selected cardiovascular events associated with dysrhythmias. For each quinolone, times to onset of the event and patient-months of observation (denominator values) were calculated. The analysis was based on two observation periods: rate of event during the first 7 days following dispensing of a prescription for each drug (W(1)), and rate of event during the second to sixth week inclusive (W(2)). Scrutiny of original green forms revealed no evidence of drug-induced hepatic dysfunction within 42 days of drug administration for any of the quinolones monitored. No evidence was found of drug-induced dysrhythmic events associated with enoxacin within 42 days of drug administration. Of the other quinolones, 'atrial fibrillation' was reported most often within 42 days following ciprofloxacin administration, with no change in event rate over that time, crude relative risk (CRR)[W(1)/W(2)] 1.0 [95% confidence interval (CI) 0.02 to 8.92]. Other less serious events associated with dysrhythmia were reported with varying incidence within 42 days of quinolone administration. The crude rate of palpitation did not change significantly over that time for ciprofloxacin, ofloxacin and norfloxacin: CRR 0.83 (95% CI 0.02 to 6.86), 2.00 (95% CI 0.19 to 12.20) and 4.99 (95% CI 0.06 to 391.94), respectively. Syncope and tachycardia were also reported for ofloxacin [CRR 9.99 (95% CI 0.52 to 589.49 for both events)] and ciprofloxacin [1.0 (95% CI 0.02, 8.92)] and 2.50 (95% CI 0.04, 47.96) for syncope and tachycardia, respectively]. It cannot be ruled out that some rare hepatic and dysrhythmic events associated with quinolones may be drug related. The primary purpose of PEM is signal generation. Compared with the other quinolones, ciprofloxacin was associated with the highest number of reports of dysrhythmic cardiovascular events occurring within 42 days of administration. This requires further investigation by other types of epidemiological study.

A view from New Zealand: comments on the prolonged QT theory of SIDS causation.

* Abbreviations: ECG = : electrocardiogram • SIDS = : sudden infant death syndrome The article by Schwartz et al1 published in the New England Journal of Medicine reports on electrocardiographic (ECG) measurements made over a period of 18 years on infants on the 3rd day of life. It identifies those infants previously studied who died suddenly and unexpectedly and were diagnosed as having died of sudden infant death syndrome (SIDS), and compares their ECGs with those of the survivors. The idea that SIDS may be related to dysrhythmic events, the predisposing factor being an abnormally long QT interval, is one that at least merits attention. However, there are problems with any investigation whose basis relies on measurement of the QT interval as the authors admit. These problems include the possibility of including U waves in the measurement, the validity of using standard formula to calculate the QTc, and how one should deal with the variation of the QT interval with variation in heart …

Ventricular dysrhythmias in ischemic heart disease.

Ischemic heart disease remains a leading killer in industrialized nations. A significant cause of the morbidity and mortality in patients with ischemic heart disease is ventricular dysrhythmic events. There is a continued search for safe and effective treatment for patients with ventricular dysrhythmias. In this article, the author discusses current understanding of the mechanisms for dysrhythmias in the setting of acute ischemia and in the chronically infarcted ventricle. Therapy for patients with ventricular tachycardia and ventricular fibrillation is reviewed. Nurses caring for cardiac patients are continually involved in rhythm monitoring and dysrhythmia interpretation. The nurse is often the first responder present when a fatal dysrhythmia occurs. In addition, nurses can be involved at all levels of care, from prevention of heart disease to assisting the patient cope with a sudden cardiac death episode.

Risk of cardiac dysrhythmias in chronic spinal cord injury patients.

The incidence of cardiac dysrhythmias is characterized in a group of 47 chronic SCI patients (greater than 30 days post injury; range 35-3605 days) with SCI lesions ranging from C4 to L3 who were referred for evaluation of a potential cardiac dysrhythmia by 24 hour Holter monitoring. Patients were grouped according to level of injury as paraplegic (T1 and below), n = 22, or quadriplegic (C3-C8), n = 25. No evidence of life threatening dysrhythmias was noted in either group, and no differences were evidenced in the incidence of cardiac dysrhythmias between the groups. Premature ventricular contractions (PVCs) were noted in 4/25 quadriplegics, and in 1/22 paraplegics, and right bundle branch block (RBBB) was noted in 1/25 quadriplegics and 1/22 paraplegics. A two-year chart review follow up revealed that no clinically significant cardiac dysrhythmic events occurred in these patients. These findings suggest that the risk of cardiac dysrhythmia is attenuated following the acute phases of SCI and represents a diminished concern to the clinician.

Spectral analysis of episodic rhythmic variations in the cutaneous electrogastrogram.

Electrical activity of the stomach can be measured using surface electrodes. The cutaneous recording of gastric electrical activity is called the electrogastrogram (EGG). Gastric electrical dysrhythmic events associated with abnormal conditions of the stomach may be detected from the EGG. An adaptive spectral analysis method which is based on autoregressive moving average modeling has previously been developed. The aim of this paper is to demonstrate the ability of the previous method in detecting gastric dysrhythmic events from the EGG. A series of bench tests stimulating typical problems with the analysis of nonstationary electric potentials was conducted. The application of the adaptive spectral analysis method to dysrhythmic events and rhythmic variations of the gastric slow wave is presented in this paper. The adaptive spectral analysis approach provides several advantages: narrow frequency peaks permitting more precise frequency identification, determination of changes in frequency components at any time point, and enhanced interpretation of cutaneous EGG recordings.