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Biomedical subjects

S Adam Strickberger

Publications and source records attributed to S Adam Strickberger.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of the coronary sinus ostium by cardiac magnetic resonance imaging.

The diameter and the angle of the coronary sinus (CS) ostium was analyzed in 101 patients who underwent cardiac magnetic resonance imaging and had left ventricular ejection fractions < or =0.35 (n = 40) or > or =0.65 (n = 61). The angle of the CS ostium in patients with LVEFs < or =0.35 was less acute than in patients with LVEFs > or =0.65 (73 degrees +/- 12 degrees vs 65 degrees +/- 10 degrees, p <0.01). There was no statistically significant difference in the diameter of the CS ostium in patients with LVEFs < or =0.35 compared with those with LVEFs > or =0.65 (8 +/- 3 vs 8 +/- 2 mm, p = 0.5). The diameter and the angle of the CS ostium were not different when analyzed on the basis of the duration of the QRS complex, left atrial dimension, or left ventricular end-diastolic dimension. In conclusion, on the basis of cardiac magnetic resonance imaging data, the angle of the CS is less acute in patients with LVEFs < or =0.35 than in those with LVEFs > or =0.65.

Aged↗
PubMed2006

AHA/ACCF Scientific Statement on the evaluation of syncope: from the American Heart Association Councils on Clinical Cardiology, Cardiovascular Nursing, Cardiovascular Disease in the Young, and Stroke, and the Quality of Care and Outcomes Research Interdisciplinary Working Group; and the American College of Cardiology Foundation: in collaboration with the Heart Rhythm Society: endorsed by the American Autonomic Society.

Explore the source record for details and available documents.

Adult↗
PubMed2005

Patient selection for cardiac resynchronization therapy: from the Council on Clinical Cardiology Subcommittee on Electrocardiography and Arrhythmias and the Quality of Care and Outcomes Research Interdisciplinary Working Group, in collaboration with the Heart Rhythm Society.

Cardiac resynchronization therapy (CRT) is a relatively new therapy for patients with symptomatic heart failure resulting from systolic dysfunction. CRT is achieved by simultaneously pacing both the left and right ventricles. Biventricular pacing resynchronizes the timing of global left ventricular depolarization and improves mechanical contractility and mitral regurgitation. Published clinical trials have demonstrated that CRT results in improved clinical status and lower mortality rate when selected patients with systolic ventricular dysfunction and heart failure are treated with CRT. This advisory identifies appropriate candidates for CRT on the basis of the inclusion criteria and results from the published clinical trials.

Arrhythmias, Cardiac↗
PubMed2005

Role of permanent pacing to prevent atrial fibrillation: science advisory from the American Heart Association Council on Clinical Cardiology (Subcommittee on Electrocardiography and Arrhythmias) and the Quality of Care and Outcomes Research Interdisciplinary Working Group, in collaboration with the Heart Rhythm Society.

This advisory summarizes the current database on pacing modalities and algorithms used to prevent and terminate atrial fibrillation (AF). On the basis of the evidence indicating that ventricular pacing is associated with a higher incidence of AF in patients with sinus node dysfunction, a patient who has a history of AF and needs a pacemaker for bradycardia should receive a physiological pacemaker (dual chamber or atrial) rather than a single-chamber ventricular pacemaker. For patients who need a dual-chamber pacemaker, efforts should be made to program the device to minimize the amount of ventricular pacing when atrioventricular conduction is intact. Many pacemakers and implantable defibrillators have features designed to prevent AF and to terminate AF with rapid atrial pacing. The evidence to support their use is limited, although these algorithms appear to be safe and usually add little additional cost. For patients who have a bradycardia indication for pacing and also have AF, no consistent data from large randomized trials support the use of alternative single-site atrial pacing, multisite right atrial pacing, biatrial pacing, overdrive pacing, or antitachycardia atrial pacing. Even fewer data support the use of atrial pacing in the management of AF in patients without symptomatic bradycardia. At present, permanent pacing to prevent AF is not indicated; however, additional studies are ongoing, which will help to clarify the role of permanent pacing for AF.

Algorithms↗
PubMed2005

Relationship between atrial tachyarrhythmias and symptoms.

OBJECTIVES: The purpose of this study was to correlate patient-reported symptoms of atrial fibrillation with the underlying rhythm. BACKGROUND: The reliability of patient-reported symptoms as a marker of atrial fibrillation recurrence has not been well studied. METHODS: This prospective multicenter trial correlated the recurrence of atrial tachyarrhythmias with symptoms in patients with a history of atrial fibrillation and a standard indication for permanent pacing. Pacemaker-detected atrial tachyarrhythmia events were correlated with symptoms. Patients logged symptomatic events into the device's memory via an external manual activator. Patients were followed for 12 months and were contacted weekly to ensure compliance with activator usage. Episodes were classified as symptomatic atrial tachyarrhythmia, asymptomatic atrial tachyarrhythmia, or symptomatic nonatrial tachyarrhythmia depending on concordance between patient symptoms and the rhythm. RESULTS: Forty-eight patients underwent implantation of a DDDRP pacemaker and were followed for 12 +/- 2 months. A median of 25.0 (4.0-55.8) symptomatic events attributed to atrial fibrillation. A median of 1.0 (0.0-10.0) symptomatic atrial tachyarrhythmia episodes were documented during follow-up. Symptoms related to atrial fibrillation were reported in 6% of atrial tachyarrhythmia episodes identified by the pacemaker. The probability that symptoms were associated with an atrial tachyarrhythmia (positive predictive value) was 17%. The ventricular rate between symptomatic and asymptomatic atrial tachyarrhythmia events was not significantly different. CONCLUSIONS: Among patients with symptomatic bradycardia and a history of atrial fibrillation, symptoms of atrial fibrillation often were not associated with documented atrial tachyarrhythmias, and more than 90% of atrial tachyarrhythmias were clinically silent.

Aged↗
PubMed2005

One conversion of ventricular fibrillation is adequate for implantable cardioverter-defibrillator implant: an analysis from the Low Energy Safety Study (LESS).

OBJECTIVES: The purpose of this study was to analyze defibrillation conversion data from the Low Energy Safety Study (LESS) to determine how implant criteria that use fewer inductions of ventricular fibrillation (VF) correlate with outcome and, in particular, to assess the reliability of using a single VF induction and test shock at 14 J. BACKGROUND: A safety margin of 10 J has become standard for implantation of an implantable cardioverter-defibrillator (ICD), but the specifics and rigor of the implant test sequence are not standardized. METHODS: In LESS, 611 ICD recipients completed a rigorous VF induction test scheme that began at 14 J and continued until the energy that succeeded three times without a failure was determined (DFT++). The data were analyzed to determine how well the outcome of the first 14-J shock and various other combinations of first and/or second shocks predicted a rigorous gold standard of DFT++ < or =21 J (i.e., three successes at < or =21 J). RESULTS: The positive predictive accuracy for the 91% of patients in whom the first 14-J shock succeeded was virtually identical to the positive predictive accuracy for the commonly used criteria of two successes at < or =17 J (99.1% vs 99.0%, P = .69), and slightly higher than the positive predictive accuracy for two successes at < or =21 J (98.8%, P = .51). A single success at 17 J or 21 J had a somewhat lower positive predictive accuracy of 98.2% (P = .17). Eliminating VF induction testing would have resulted in a significantly lower positive predictive accuracy of 97.1% (P = .01). CONCLUSIONS: A single conversion success at 14 J on the first VF induction provides similar positive predictive accuracy as two successes at 17 J or 21 J. Using this criterion, 91% of patients meet implant criteria with a single induction of ventricular fibrillation.

Aged↗
PubMed2005

Cardiac resynchronization therapy for congestive heart failure.

Cardiac resynchronization represents a novel therapeutic strategy for the treatment of congestive heart failure due to systolic dysfunction. Since its modest beginnings in the 1990s, cardiac resynchronization therapy has gained widespread acceptance as a useful adjunct to pharmacologic therapy for congestive heart failure. Randomized trials have consistently shown functional improvement in patients with congestive heart failure due to systolic dysfunction, a wide QRS complex on electrocardiogram and sinus rhythm, that are treated with cardiac resynchronization therapy. This review article will address the rationale, mechanisms of action, limitations and appropriate selection of patients for cardiac resynchronization therapy.

Cardiac Pacing, Artificial↗
PubMed2004

Clinical assessment and management of patients with implanted cardioverter-defibrillators presenting to nonelectrophysiologists.

All physicians increasingly will encounter patients who have implanted cardioverter-defibrillators (ICDs) for protection from ventricular arrhythmias. This advisory provides a concise summary relevant to the assessment and management of patients with ICDs, including those who present to primary care or emergency department physicians with symptoms suggesting arrhythmia or ICD malfunction and those who require cardiac or surgical procedures.

Anti-Arrhythmia Agents↗
PubMed2004

Is defibrillation testing required for defibrillator implantation?

The assessment of defibrillation (DFT) efficacy has long been the standard of care during defibrillator implantation. To ensure an acceptable DFT safety margin, early defibrillator systems frequently required that the shock polarity and the location, type, or number of electrodes had to be altered. Advances in defibrillator and lead technology have resulted in lower and more consistent DFT thresholds in the range of 10 J, with an infrequent requirement to modify the DFT system. Yet, one can make an argument for and against continuation of DFT testing at the time of defibrillator implantation. The goal of this paper is to address both the data that do support and the data that do not support continuation of DFT testing at the time of device implantation. Scientifically, DFT testing should be abandoned only when prospective evidence demonstrates that defibrillator implantation without testing is as safe and has the same mortality benefits as implantation with testing. The most attractive aspect of eliminating DFT efficacy testing is that more patients may have the opportunity to be treated with this life-saving therapy. Perhaps there are alternative strategies to improve accessibility to defibrillator therapy without possibly eroding its effectiveness. In the end, will lives be saved or lost if we discontinue DFT efficacy testing and lower the barriers to implantable defibrillator therapy?

Defibrillators, Implantable↗
PubMed2003

Amiodarone versus implantable cardioverter-defibrillator:randomized trial in patients with nonischemic dilated cardiomyopathy and asymptomatic nonsustained ventricular tachycardia--AMIOVIRT.

OBJECTIVES: The purpose of this multicenter randomized trial was to compare total mortality during therapy with amiodarone or an implantable cardioverter-defibrillator (ICD) in patients with nonischemic dilated cardiomyopathy (NIDCM) and nonsustained ventricular tachycardia (NSVT). BACKGROUND: Whether an ICD reduces mortality more than amiodarone in patients with NIDCM and NSVT is unknown. METHODS: One hundred three patients with NIDCM, left ventricular ejection fraction < or =0.35, and asymptomatic NSVT were randomized to receive either amiodarone or an ICD. The primary end point was total mortality. Secondary end points included arrhythmia-free survival, quality of life, and costs. RESULTS: The study was stopped when the prospective stopping rule for futility was reached. The percent of patients surviving at one year (90% vs. 96%) and three years (88% vs. 87%) in the amiodarone and ICD groups, respectively, were not statistically different (p = 0.8). Quality of life was also similar with each therapy (p = NS). There was a trend with amiodarone, as compared to the ICD, towards improved arrhythmia-free survival (p = 0.1) and lower costs during the first year of therapy ($8,879 US dollars vs. $22,039 US dollars, p = 0.1). CONCLUSIONS: Mortality and quality of life in patients with NIDCM and NSVT treated with amiodarone or an ICD are not statistically different. There is a trend towards a more beneficial cost profile and improved arrhythmia-free survival with amiodarone therapy.

Amiodarone↗
PubMed2003

Effects of operator experience on the outcome and duration of pulmonary vein isolation procedures for atrial fibrillation.

Segmental, ostial ablation to isolate the pulmonary veins has been shown to be effective for the treatment of atrial fibrillation (AF). The purpose of this study was to determine the effects of operator experience on the outcome and duration of pulmonary vein isolation procedures for AF. One hundred three consecutive patients with AF underwent segmental, ostial ablation to isolate pulmonary veins. The effect of operator experience on the outcome and duration of the procedure was measured. The mean procedure duration was 232 +/- 70 minutes (range 50 to 460). There was an indirect linear relation between the total procedure time and the number of procedures performed (r = -0.68; p <0.001), and between the total fluoroscopic time and the number of procedures performed (r = -0.71; p <0.001). The percentage of patients in whom complete isolation of the pulmonary veins was achieved and the total duration of radiofrequency energy delivered during the procedures remained stable as operator experience increased. Operator experience was not an independent predictor of recurrent AF. The primary effect of operator experience on pulmonary vein isolation procedures for AF was a marked reduction in the duration of the procedure and fluoroscopic time. Long procedure durations and large amounts of radiation exposure may currently limit the widespread application of this therapy. The results of this study suggest that after >75 cases, segmental ablation to isolate the pulmonary veins using fluoroscopy and conventional radiofrequency ablation usually is feasible in <3 hours.

Adult↗