Lesson plan
Afterload
Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on the left and right ventricles respectively. Afterload changes to adapt to the continually changing demands on an animal's cardiovascular system. Afterload is proportional to mean systolic blood pressure and is measured in millimeters of mercury (mm Hg). The clinical concept of afterload was given its modern operational definitions through the work of American cardiologist Edmund Sonnenblick and colleagues at the National Institutes of Health in the early 1960s. Sonnenblick's force-velocity studies of isolated cardiac muscle demonstrated that afterload directly determines the velocity of myocardial fiber shortening, providing the theoretical basis for afterload reduction as a therapeutic strategy in heart failure.
Article summary
Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on the left and right ventricles respectively. Afterload changes to adapt to the continually changing demands on an animal's cardiovascular system. Afterload is proportional to mean systolic blood pressure and is measured in millimeters of mercury (mm Hg). The clinical concept of afterload was given its modern operational definitions through the work of American cardiologist Edmund Sonnenblick and colleagues at the National Institutes of Health in the early 1960s. Sonnenblick's force-velocity studies of isolated cardiac muscle demonstrated that afterload directly determines the velocity of myocardial fiber shortening, providing the theoretical basis for afterload reduction as a therapeutic strategy in heart failure.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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