According to the study, published in the Journal of Cardiovascular Electrophysiology, thirteen goats were subjected to rapid atrioventricular (AV) pacing with high atrial and ventricular rates (240 beats/min) while an additional five goats were subjected to a high atrial rate (240 beats/min) and low, regular ventricular rate (80 beats/min). Six of the 13 goats in the first group died suddenly after developing signs of end-stage CHF. No goats died from the group with the low ventricular rate.
"The results of this experimental research demonstrate that the changes in atrial function and structure that evolve during a chronic atrial tachyarrhythmia do not relate to the high atrial rate itself but rather to the concurrent high ventricular rate and the consequent development of heart failure," states lead researcher, Bas A. Schoonderwoerd, MD, PhD.
Changes in atrial function and structure are known as atrial remodeling. Schoonderwoerd explains that this remodeling can make it more difficult to regain normal heart rhythms; remodeling can even be induced by heart failure itself. The high pressure and irregular pumping caused by the high rates used in the first group of goats are similar to the rapid rates of atrial fibrillation and can cause the heart ventricles to wear out.
"This may imply that in patients with atrial fibrillation, we must aim at keeping the ventricular rate low [with drugs] and thus prevent the development or inhibit the progression of heart failure," adds Schoonderwoerd.
Increased levels of atrial natriuretic peptides (ANP), a cardiac hormone that regulates blood pressure, are also noted in this experiment. The researchers conclude that "a rise in atrial rate results in an additional increase of circulating ANP, but only in the presence of elevated atrial pressures." ANP levels also rise with atrial pressure, independent of atrial rate. CHF developed in the animals of the experiment that showed sustained ANP release and high ventricular rates.
More research is needed to support this evidence in human models due to interspecies differences and because arrhythmia and/or heart failure is usually present in a clinical situation for many months.
These studies are published in the Journal of Cardiovascular Electrophysiology. Media wishing to receive PDFs of these articles please contact firstname.lastname@example.org.
About the Author
Bas A. Schoonderwoerd, M.D., Ph.D., has conducted past research in the field of atrial fibrillation and heart failure, and atrial remodeling due to tachycardia and heart failure. He is currently affiliated with the Department of Cardiology, Thoraxcenter, University Hospital Goningen in The Netherlands. Dr. Schoonderwoerd can be reached for questions and interviews at B.A.Schoonderwoerd@thorax.azg.nl or 31-50-3612355.
About the Journal of Cardiovascular Electrophysiology
Journal of Cardiovascular Electrophysiology (JCE) keeps its readership well informed of the latest developments in the study and management of arrhythmic disorders. Edited by Eric N. Prystowsky, M.D., and a distinguished international editorial board, JCE is the leading journal devoted to the study of the electrophysiology of the heart and blood vessels. Each issue of JCE contains peer-reviewed research, original investigations, scholarly reviews, editorials, case reports, and letters to the editor. Special Features appearing each month include Point of View, Arrhythmia Rounds, and Techniques and Technology. In addition, time-sensitive information is frequently published as supplementary issues.
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