Page 12, Cardiac Performance, Dr. D. Penney
The contractile state is increased by circulating catecholamines, Ca++, sympathetic nerve impulses, the Bowditch effect, inotropic agents, cardiac glycosides (digitalis), etc. Contractile state is decreased by ischemia, acidosis, loss of myocardium (heart attack), acetylcholine, pharmacologic depressants, heart failure, etc. Increased contractility like increased preload and decreased afterload, increases stroke volume; decreased contractility like decreased preload and increased afterload, decreases stroke volume.
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