Circulation
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Patients receiving oral hypoglycemic agents for diabetes mellitus are at increased risk of cardiovascular mortality. Oral hypoglycemic agents are inhibitors of the ATP-sensitive potassium (KATP) channel. Ischemic preconditioning is mediated by KATP channel activation. We therefore hypothesized that myocardium from patients taking long-term oral hypoglycemic agents would be resistant to the protection by ischemic preconditioning. ⋯ Human myocardium from patients without long-term exposure to oral hypoglycemic agents is functionally protected by preconditioning. Long-term oral hypoglycemic intake blocks the protection by preconditioning. These data suggest that ischemic preconditioning in human myocardium relies on KATP channels, and long-term inhibition of KATP channels with oral hypoglycemic agents may explain the excess cardiovascular mortality in these patients.
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Review Practice Guideline Guideline
Prevention of bacterial endocarditis. Recommendations by the American Heart Association.
To update recommendations issued by the American Heart Association last published in 1990 for the prevention of bacterial endocarditis in individuals at risk for this disease. ⋯ Major changes in the updated recommendations include the following: (1) emphasis that most cases of endocarditis are not attributable to an invasive procedure; (2) cardiac conditions are stratified into high-, moderate-, and negligible-risk categories based on potential outcome if endocarditis develops; (3) procedures that may cause bacteremia and for which prophylaxis is recommended are more clearly specified; (4) an algorithm was developed to more clearly define when prophylaxis is recommended for patients with mitral valve prolapse; (5) for oral or dental procedures the initial amoxicillin dose is reduced to 2 g, a follow-up antibiotic dose is no longer recommended, erythromycin is no longer recommended for penicillin-allergic individuals, but clindamycin and other alternatives are offered; and (6) for gastrointestinal or genitourinary procedures, the prophylactic regimens have been simplified. These changes were instituted to more clearly define when prophylaxis is or is not recommended, improve practitioner and patient compliance, reduce cost and potential gastrointestinal adverse effects, and approach more uniform worldwide recommendations.
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Clinical Trial Controlled Clinical Trial
Low-energy cardioversion of spontaneous atrial fibrillation. Immediate and long-term results.
Recent studies have suggested that induced atrial fibrillation (AF) could be successfully terminated by using a two-catheter electrode system and low energy (< 400 V). This study evaluated the efficacy and safety of low-energy cardioversion in spontaneous chronic and paroxysmal AF. ⋯ Atrial defibrillation using low energy between two intracardiac catheters with an electrical field between the right and left atria and the protocol used is feasible in patients with persistent spontaneous AF. The technique is safe provided synchronization to the R wave is achieved. A low recurrence rate of AF was seen in patients in whom sinus rhythm was restored.
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Clinical Trial Controlled Clinical Trial
Abnormal awake respiratory patterns are common in chronic heart failure and may prevent evaluation of autonomic tone by measures of heart rate variability.
Reduced heart rate variability, particularly in the Very-low-frequency (VLF) spectral band, has been found to be a marker for poor prognosis in patients after myocardial infarction, but the origin of the VLF oscillations is unclear. In this study, we demonstrate that the power of cardiovascular oscillations in the VLF band in awake patients with mild to severe chronic heart failure is greatly increased by the common occurrence of unrecognized irregularity of breathing, which may confound the use of heart rate variability measures as indexes of autonomic tone or prognosis. ⋯ Breathing disorders are surprisingly common in awake patients with poor left ventricular function and produce large VLF oscillations in heart rate variability. If measures of heart rate variability are used for prognostic purposes during both short-term and long-term recordings, the confounding effects of variable respiratory patterns should be excluded. Respiratory rehabilitation might help control potentially hazardous surges in sympathetic tone.