Step I Contractility

[aspiringmd1015]

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does Contractility increase w/ Increased HR? BRS says it does bc w/an increased HR, you'll have a higher Intracellular ca2+ concnetration. Its not listed in FA so thats why im asking.

 

[elbandito123]

Not necessarily. Things that affect heart rate have a chronotropic effect, while things that affect contractility will have an inotropic effect. While a lot of times we will see both an increase in contractility and heart rate together (ie. sympathetic activation), that is not the rule. For instance, the drug Digoxin will have a positive inotropic effect, but will have a negative / no effect on chronotrophy. Hope this helps.

 

[aspiringmd1015]

i get what youre saying, but it didnt answer the context of what my questoin was asking, i wasnt asking if chronotropic and inotropic effects will always be the same, im asking if by increasing your HR(chronotropic) can increase your contractility, A/c To BRS, its true. Its not mentoined in FA so its either its something they left out, or not important enough.