Articulo sobre frecuenci cardiaca

TOWARD CONSISTENT DEFINITIONS FOR PRELOAD AND AFTERLOAD
James M. Norton
Advan Physiol Educ 25:53-61, 2001. You might find this additional information useful... This article has been cited by 4 other HighWire hosted articles: Miniature Intracardiac Assist Device Provides More Effective Cardiac Unloading and Circulatory Support During Severe Left Heart Failure Than Intraaortic Balloon Pumping K.D. Reesink, A. L. Dekker, V. van Ommen, C. Soemers, G. G. Geskes, F. H. van der Veen and J. G. Maessen Chest, September 1, 2004; 126 (3): 896-902. [Abstract] [Full Text] [PDF] REPLY J. M. Norton Advan Physiol Educ, June 1, 2003; 27 (2): 89-90. [Full Text] [PDF] Toward consistent definitions for preload and afterload--revisited C. ROTHE Advan Physiol Educ, March 1, 2003; 27 (1): 44-45. [Abstract][Full Text] [PDF] Cardiovascular interactions: an interactive tutorial and mathematical model C. F. Rothe and J. M. Gersting Advan Physiol Educ, June 1, 2002; 26 (2): 98-109. [Abstract] [Full Text] [PDF] Medline items on this article's topics can be found at http://highwire.stanford.edu/lists/artbytopic.dtl on the following topics: Medicine .. Heart Wall Medicine .. Blood Pressure Education ..Textbooks Updated information and services including high-resolution figures, can be found at: http://ajpadvan.physiology.org/cgi/content/full/25/1/53 Additional material and information about Advances in Physiology Education can be found at: http://www.the-aps.org/publications/advan

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Advances in Physiology Education is dedicated to the improvement of teaching and learning physiology, both in specialized courses and in the broader context of general biology education. It is published four times a year in March, June, September and December by the American Physiological Society, 9650 Rockville Pike, Bethesda MD 20814-3991. Copyright © 2005 by the American PhysiologicalSociety. ISSN: 1043-4046, ESSN: 1522-1229. Visit our website at http://www.the-aps.org/.

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TOWARD CONSISTENT DEFINITIONS FOR PRELOAD AND AFTERLOAD
James M. Norton Department of Physiology and Pharmacology; University of New England College of Osteopathic Medicine, Biddeford, Maine 04005

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ignificant differences exist among textbook definitions for the terms preloadand afterload, leading to confusion and frustration among students and faculty alike. Many faculty also chose to use in their teaching simple terms such as “end-diastolic volume” or “aortic pressure” as common-usage approximations of preload and afterload, respectively, but these are only partial representations of these important concepts. Straightforward definitions both of preload and afterloadthat are concise yet still comprehensive can be developed using the Law of LaPlace to describe the relationships among chamber pressure, chamber radius, and wall thickness. Within this context, the term “preload” can be defined as all of the factors that contribute to passive ventricular wall stress (or tension) at the end of diastole, and the term “afterload” can be defined as all of the factorsthat contribute to total myocardial wall stress (or tension) during systolic ejection. The inclusion of “wall stress” in both definitions helps the student appreciate both the complexities of cardiac pathophysiology and the rationale for therapeutic intervention.
ADV PHYSIOL EDUC 25: 53– 61, 2001.

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Key words: Law of LaPlace; walltension; wall stress; cardiac remodeling; hypertrophy

Recent changes in the basic science curriculum at the University of New England College of Osteopathic Medicine have included a reduction in the number of classroom contact hours devoted to the traditional lecture format. These reductions have prompted (i.e., required) faculty to be more creative and productive in their use of their formal...