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In a situation where a patient's heart isn't strong enough for surgery, why isn't it common for a doctor to give the patient epinephrine before the surgery? Do the effects of epinephrine not last long enough, or have potentially harmful effects in larger quantities?
Edit: Is it that the patient's blood flow is also increased when using epinephrine, making blood loss more significant?
Aadrenaline will generally quickly worsen heart failure because
Do the effects of epinephrine not last long enough
The effects of epinephrine are indeed short but so are most ionotropic drugs - this is irrelevant however since if it were to be used in surgery it would be given via continuous infusion or repeated iv bolus doses.
... or have potentially harmful effects in larger quantities?
It has potentially harmful effects even in small quantities in heart failure.
Is it that the patient's blood flow is also increased when using epinephrine, making blood loss more significant?
No.
The exact opposite. A major function of epinephrine in the body is to minimize blood loss in the case of trauma by inducing profound peripheral vasoconstriction. This is why for example it is often used topically to treat acute epistaxis (nose bleeds). So while it does under normal circumstances increase cardiac output it would be incorrect to say it "increases blood flow".
Although epinephrine does have important uses in surgery (to treat for example low blood pressure in the setting of bradycardia) there are generally more effective alternative drugs when it comes to heart failure (dobutamine for example).
The blocking of adrenaline is in fact a cornerstone in the treatment of heart failure which is why beta-blockers (i.e beta-adrenergic receptor blockers) are usually prescribed to patients with heart failure.
Generally, in intensive care medicine there are variants of catecholamines (the general class epinephrine belongs to) that can be applied to increase heart output. However, there are various drawbacks to this therapy, including putting increased strain on an already strained muscle and the effect of e. g. epinephrine on all the other organs of the body.
For side effects of epinephrine and catecholamines in general see e. g. here: https://www.researchgate.net/figure/Adverse-and-beneficial-effects-of-catecholamines_tbl1_316052992
Is it that the patient's blood flow is also increased when using epinephrine, making blood loss more significant?More blood volume output per time can increase bleeding (if it the heart is sufficiently able to increase volume output from increased activation). That said, flow and pressure are two different things to consider - peripherally epinephrine casues vasoconstriction and may decrease blood flow. Still, that very same vasoconstriction may in turn increase blood pressure and wash away previously formed blood clots, which is why epinephrine (or increasing blood pressure) may result in increased bleeding.
Generally speaking treatment of heart failure (the insufficiency of the heart to pump blood) has a variety of approaches depending on the cause and stage of heart failure.
For maintenance, generally the heart's work is reduced by trying to decrease peripheral resistance to pumping and/or decreasing volume to be pumped e. g. by increasing extraction of water in the kidney.
