Effects of Anesthesia on the Heart

Heart rate and rhythm are monitored during anesthesia. The overall function of the cardiovascular system is also indicated by the blood pressure and oxygen level on the monitor.
Heart rate and rhythm are monitored during anesthesia. The overall function of the cardiovascular system is also indicated by the blood pressure and oxygen level on the monitor. | Source

Anesthesia Affects Heart Function

Different types of anesthesia affect the heart in different ways. As a board-certified anesthesiologist, I see these effects each and every day on healthy and sick hearts. Anticipating and understanding these issues is important to successful delivery of anesthesia.

In most cases, and with most anesthesia regimens, the overall effect will be to DEPRESS HEART FUNCTION. The physiology of the heart is complex, as is the pharmacology of anesthetic medications. This means that sometimes, the effects will be unpredictable and there will always be exceptions to every rule.

NOTE: Anesthesia here will refer to general anesthesia, where unconsciousness is achieved and maintained during surgery.

Normal Heart Function- To Understand How Anesthesia Affects the Heart Requires a Knowledge of Normal Heart Function. This Video Provides a Good Introduction

The Heart - Anatomy and Physiology Basics

The heart is often referred to as a four-chamber pump. Blood returns from the body to the right side of the heart. It then goes to the lungs to get filled with oxygen. The oxygenated blood then flows to the left side of the heart to be pumped out to the body to deliver that oxygen.

In order to be an effective pump, the heart functions through an intricate and ordered interplay of electric signals, muscle contractions and one-way valves.

The self-generated electrical signals send a wave of current down special conducting fibers in a specific pattern. This triggers certain parts of the heart muscle to contract in an ordered manner. This wave of contractions squeezes blood out of each ventricle (large pumping chamber), through valves that open and allows blood to return to the atria (collecting chambers). The strength of contraction ensures that most of the blood in the chamber is squeezed out with each heart beat.

Any disruption in this pattern can affect heart function. Anesthesia can interrupt this pathway in several different ways.

In discussing the cardiac implications of anesthesia medicines, usually, we either have a drug and wonder about its effects on the heart, or we have specific effect and want to know which drugs can cause it. Both approaches are presented below to make the information easier to find. Only the most typical examples of the most common anesthesia drugs are presented as a thorough discussion would require textbook length consideration.

Cardiac Effects of Common Anesthetic Agents

The table below gives examples of some common individual anesthetic agents and their heart effects. Keep in mind that for each effect, there is likely a study or two that disputes the findings. The data here are consistent with the current edition of the authoritative text, "Miller's Anesthesia" (7ed., 2009). The conflicting conclusions show how complex these interactions are, and how the education and experience of the anesthesia provider helps keep us safe during anesthetics.

  • Propofol, etomidate and pentothal are 'induction' agents used to get patients to sleep.
  • Ketamine is a unique drug that may be used for sedation, as well as induction and maintenance of anesthesia.
  • Fentanyl and morphine are pain medicines used before, during and after surgery.
  • Succinylcholine is a muscle relaxant that makes placement of the breathing tube and surgery easier to achieve.
  • Halothane, isoflurane and sevoflurane are anesthesia gases used to keep patients asleep for surgery, delivered through a breathing tube or mask.

Heart Rate
Heart Rhythm
no significant change to decreases at higher doses
little effect, potential benefit in slowing heart rate in some fast arrythmias
little effect to ability to decrease cardiac output at higher doses
increases by 10-40%
potential disruption, prolong QT interval
decreases cardiac output
mimimal effect
minimal effect
minimal effect
no specific changes
variable, but overall may prevent some arrhythmias
little change to mild increase
variable, but overall may prevent some arrhythmias
uncertain, may be similar to fentanyl
variable, usually decreases especially at usual doses and after a second dose
increases likelihood of several kinds of arrhythmias
decreases at usual doses
no change to little change
increases likelihood of arrythmias
potential changes, but of unknown significance
potential changes, but of unknown significance
This is NOT a comprehensive list of anesthetic agents- these are examples only. Likewise, the effects may vary depending on a large number of factors and interactions. No clinical practice advice is implied, nor should this chart be used for such. Ea

Anesthesia Machine and Monitor

IV and inhaled agents are combined to deliver a general anesthetic, in most cases.
IV and inhaled agents are combined to deliver a general anesthetic, in most cases. | Source

Effects of Anesthesia on the Heart Vary

The effect that anesthesia has on the heart is influenced by

  • Preoperative heart function
  • Any heart disease including blockages in arteries (coronary disease), valve problems, high blood pressure,
  • The type of anesthesia
  • The specific medications used during anesthesia
  • Medications taken by the patient
  • Other coexisting disease

Overall Effect of General Anesthesia on Heart Function

There are many cardiac parameters to consider when giving an anesthetic. Most commonly, we may be concerned about the effect of anesthesia on heart rate, heart rhythm and the strength of pumping action of the heart (contractility). The described effects are very broad generalizations, only.

In reality, multiple agents in combination are used for each anesthetic on a patient, so it is often difficult to predict or know which drug is causing the predominant effect. In addition, anesthesiologists can use these medications in varying amounts, dosages and combinations to achieve, or prevent, a certain effect on the heart.

Anesthesia Effects on Heart Rate

A human's resting heart rate is determined by numerous and complex factors. Any stress on the body will usually cause an increase in heart rate, and this can include surgery and anesthesia.

  • Induction agents tend to allow increased heart rate in low doses and slowed heart rate in higher doses.
  • Narcotic pain medicines tend to slow heart rate (except for meperidine which increases heart rate).
  • Succinylcholine will decrease heart rate. This can actually be dangerous in certain situations and must be monitored closely in those at risk.
  • Anesthesia gases have variable effects, influenced by many factors.

Anesthesia and Heart Rhythm

Many anesthetic agents have the potential to cause irregular heart rhythms. Patients with pre-existing arrhythmias and abnormal blood electrolytes (calcium, magnesium, potassium) are most at risk. In addition, a patient's medications influence the potential for arrythmias, as well.


Anesthesia Effects on Contractility

Overall, general anesthesia at levels high enough to maintain unconsciousness, will decrease the strength of contraction. Individual medications have variable effects as seen in the above table.

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Comments 28 comments

TFScientist profile image

TFScientist 4 years ago from Peterborough, UK

I hadn't even considered that an anaesthetic would have an effect on the human body above that of consciousness...but then I suppose it makes sense considering the extra training one must go through to administer anaesthetic. A really interesting read, well presented with good summaries.

Voted up, interesting and shared.


alliemacb profile image

alliemacb 4 years ago from Scotland

This is a very interesting hub that outlines the potential risks of anaesthetic. Voted up and interesting.

Marcy Goodfleisch profile image

Marcy Goodfleisch 4 years ago from Planet Earth

This is so well-researched and presented! I've had a few surgeries here and there, and I think the biggest fear many people have with routine surgery is about the 'going under' part rather than actual procedure. Anesthesia is a mystery to most of us; thanks for helping to shed light on something many of us will experience at some point in life.

Voted up,useful and interesting.

teamrn profile image

teamrn 4 years ago from Chicago

Tahoe, I enjoyed reading your pice with it's review of induction agents, etc. I have a procedure with IV sedation soon and while IV sedation and GA are different (am I right?), I needed the the refresher to quell concerns that I have.

TahoeDoc profile image

TahoeDoc 4 years ago from Lake Tahoe, California Author

Hello there!

Yep, general anesthesia means you will be unconscious, and often need airway management to ensure adequate oxygen delivery. Sedation means you will be relaxed, but conscious, usually only needing a face mask or nasal prongs for supplemental oxygen. Sometimes, this will be called 'twilight sleep' or MAC (for monitored anesthesia care). The doctor doing the procedure uses local numbing medicine to prevent pain with the procedure.

Good luck!

teamrn profile image

teamrn 4 years ago from Chicago

Tahoe, Does the doc doing the anesthesia determine which is the best suited for you-or what is the safest? Who makes the judgment; the doc?

TahoeDoc profile image

TahoeDoc 4 years ago from Lake Tahoe, California Author

It's usually a joint decision, BUT for some procedures, there is a choice that will be MUCH better than others. The anesthesiologist will review the procedure and your medical history. There may be a reason they have a strong preference for one type or another. There are some surgeons I work with who are just not that good at doing local anesthesia, for example. So, I may recommend general anesthesia or deeper sedation for those cases, even though local anesthesia is an option. Once in a while, a surgeon will not want or will want a specific type of anesthesia. Cataract surgeries, for example, are done with just a little sedation. When the ophthalmologist says "look up" or "look down", the patient needs to be able to follow directions. They cannot do this if they are deeply sedated or unconscious.

Does that make sense? The options are weighed, sometimes there are choices that are fairly equivalent. Sometimes, for a whole bunch of reasons, one choice will be just superior enough to recommend it.

You can always ask your anesthesiologist what options are available, and what they recommend. If you have, or think you have, a preference for another type, it can't hurt to ask if it's an option. Maybe it isn't, but at least you would know.

Does that help?

teamrn profile image

teamrn 4 years ago from Chicago

Muchas gracias. I'm having some oral surgery and the doc offers IV sedation + local or GA. I have a considerable medical hx, so I'd imagine that he'd want GA. He hasn't said otherwise.

TahoeDoc profile image

TahoeDoc 4 years ago from Lake Tahoe, California Author

Usually, the more significant the medical history, the more we try to AVOID general anesthesia. General anesthesia affects more of your body systems, and more significantly than local and sedation. Now, if sedation with local isn't adequate and heart rate and blood pressure are high due to pain and anxiety, that is a case for general anesthesia, but I'd say it's less likely to be recommended for you.

teamrn profile image

teamrn 4 years ago from Chicago

HR and BP aren't a problem, so I'll discuss w/ MD; I'm sure he has a preference. Thanks for thoughts and a well-written hub!

I think the importance of anesthesiologists is minimized tooooo much. Do you mind if I post it on my FB wall; one of my goals since I can't work anymore, us patient education and therefore advocacy.

TahoeDoc profile image

TahoeDoc 4 years ago from Lake Tahoe, California Author

How did I miss your last wonderful comment! I would be delighted to have you share this and any hub you find useful. I really want to help people understand and make it easier to sort through the overwhelming amount of medical info out there!!

Thanks again friend, for your kind words and support. 3 years ago

I have stones in my gallbladder of size 7 mm to 4 mm.I went for the operation but the anesthetist found my heart beat ranging between 35 and 60 per minute.Was referred to a heart specialist who declared me fit for the operation after monitoring my heart beats for 24 hours by fixing a holter . Is this operation safe for me ?

TahoeDoc profile image

TahoeDoc 3 years ago from Lake Tahoe, California Author

Yes. A slow heartbeat can be a cause for concern, but it can also be normal. The referral to the heart specialist was the appropriate course of action. If they found no problems, then you should be fine. Just make sure the anesthetist knows about the issue and the findings. They can give medicines to make sure the heart rate doesn't go lower.

Good luck- you will be fine.

Peter 3 years ago

Hi there TahoeDoc and thanks for the informative article. I've always had a (healthy, verified) slow resting pulse of anywhere between 45-65, but since a septoplasty under GA 3.5 weeks ago my pulse has been quickest and blood pressure slightly lowered. Hr is now high 70's / early 80's. I felt very wiped out after the surgery and still don't feel good now. My O2 stats also low from 93 (unusual) to around 95/96 (normal) although this could be due to mouth breathing only. Is this a possible normal side effect from GA? 36 and otherwise healthy. Really appreciate any insight or reassurance you could give. Thanks!

sandhya 2 years ago

to undergo any surgery what is the heart rate and temperature

TahoeDoc profile image

TahoeDoc 2 years ago from Lake Tahoe, California Author

Before the start of surgery, the temperature and heart rate should be normal or within normal limits for the patient. During surgery, they should remain there unless changes are required (cooling during cardiopulmonary bypass for example).

I'm not sure I understood the question though

Cris C. 2 years ago

This blog has been extremely helpful. I will be having a breast augmentation next month but I am horrified to be put under GA. Iam a healthy individual with no pre existing conditions, however; I do suffer from anxiety. Sometimes I feel an abnormality in my heart palpitations and have somewhat of a concern with anesthesia. I've had an EKG in the past and no abnormalities were detected. I'm also very sensitive to narcotics and are allergic to morphine and dilaudid. Any advice on this? Thank you.

TahoeDoc profile image

TahoeDoc 2 years ago from Lake Tahoe, California Author

It sounds like you will do great under anesthesia. Anxiety is tough to control, especially when facing the unknown. But, practice some relaxation techniques- breathing, internal dialogue, etc. From your description, you are healthier than most people who get anesthesia.

The palpitations can definitely be related to anxiety, especially if you also drink caffeine, alcohol, and so on. You had an EKG which was negative. The only other thing you could do is ask your medical doc if he/she has any further concerns with the palpitations. Likely, there is no other test or concern for this as it is pretty common. But, your doc can ask more specific questions about the symptoms to make sure there is no further testing that you should have before elective surgery.

Please note: There is a difference between sensitivities, side effects and allergies to narcotics. Are you sensitive?-- means you don't need much to get the effect and may get side effects more easily. Side effects of narcotics include itching, nausea & vomiting and sedation. Allergies involve an immune system reaction creating a rash, hives or a severe reaction in which a patient has swelling of the airway resulting in trouble breathing, throat closing and wheezing as well as low blood pressure and potentially shock and death.

Please let your doctors know whether you truly have an allergy or if not, what reaction you do have to the narcotics you mention. It helps them know what to give, avoid and what is safe to substitute.

Good luck. I suspect that you will do just fine.

jen 2 years ago

I had a random day of bigeminal pvc's about 9 months ago (thought to be caused by either an antibiotic or antifungal I was taking) after the emergency room cleared me as healthy I left and went to a cardiologist. after e heart echo, 2 more ekgs, 24 hour holter and stress test I was told my heart is 100% healthy and it was a random isolated event. I am having cosmetic surgery in 3 weeks and because of this past event I am having some serious anxiety about the anesthesia. I went to a Dr and had an EKG, blood work and got her medical clearance to have surgery. I am very healthy, clean eater and regularly exercise, 30 years old. I have also been under general when I was a child and iv sedation as a young adult. I definitely suffer from an anxiety disorder and I am obsessing about this surgery. Do you think I sound like someone whose heart and everything else will be okay under the hour of anesthesia? I really want to go into this calmly with a level head!

TahoeDoc profile image

TahoeDoc 2 years ago from Lake Tahoe, California Author

Even without those tests, I would expect you to do well. The fact that you already had EKGs on more than one occasion, an echo, a holter tests and a stress test- you would be the most reassuring patient I would have in a month as far as your heart goes.

I think the anxiety is causing you to worry too much. The very best thing you can do for yourself is practice relaxation breathing and thinking. I promise, this will make a difference for you. An hour under anesthesia will be nothing for you physiologically based on what you have said.

Even without all this other info and testing, the fact that you are healthy with good exercise tolerance would make me feel very, very comfortable anesthetizing you- even if you had an isolated period of bigeminy. By the way, I've done (which means other anesthesiologists have too) hours of serious, major, emergency surgery on older people with hardened arteries and lots of other medical issues who were in bigeminy AT THE TIME of their surgery and they did ok, if that helps at all.

I hope this helps reassure you. When I talk to my patients, I tell them that I can't take away all the risk, but I can help minimize it. You are way ahead of the game by having had all those tests done- most people, even with your history, may not have all that info to give to the anesthesiologist.

Now, do your best to relax, breathe and focus on the positive. It really, really helps in waking up from anesthesia and for early recovery (and probably late recovery too- I just don't see that).

Good luck to you, but luck will really not have anything to do with it. You are a dream patient, physiologically, for an anesthesia provider.:) :)

jen 2 years ago

wow thank you so much for that detailed response!! I have to tell you as I was reading that, the huge knot in my stomach actually unraveled itself. I really hope the anesthesiologist that shows up the day of my procedure is a caring one like you. That too made me nervous that its just s group of them that go to surgical centers when needed, but my Dr assured me he only uses the best, highly qualified so I'm trusting that! it seems to be a very common fear, that fear of being put under. I don't know why my brain likes to scare me. I am convinced my heart will stop from the anesthetic like they will give me too much ( I do tend to be medication sensitive and usually only need a half dose of anything I take that's probably why I'm scared) but someone else told me for such a simple one hour procedure they do tend to go lighter on the anesthesia so you have a quick time waking up. is there any truth to that or just one of those silly rumors?!

TahoeDoc profile image

TahoeDoc 2 years ago from Lake Tahoe, California Author

True. :) and the anesthesia is titrated to what you need. Your heart rate, blood pressure, EKG, oxygen level & breathing are monitored continuously to keep you safe & give you just the right amount of anesthesia.

Smile, breathe, relax. The anticipation, worry & waiting are way worse than the anesthesia. :)

Cris C. 2 years ago

Thank you so much for the wonderful knowledgeable advice. I am defenetely very sensitive to narcotics but I do have an allergy to dilaudid. I also keep dreading the surgery since I have never been under general anesthesia, however; with the examples you provided I feel more at ease. I am also a very healthy individual who exercises regularly and practices healthy eating habits most of the time. I guess the fear of the unknown can be triggering me to worry more than the normal and may cause my heart to beat weir sometimes. Hope to have such a caring anesthesiologist like you at the time of my surgery. Thank you again, this is such an awesome blog and you ate amazing!!

TahoeDoc profile image

TahoeDoc 2 years ago from Lake Tahoe, California Author

Thank you and the fact that this helped at least a couple of you makes it worth writing and keeping up here. Good luck and let me know how it goes!

Valdoria 16 months ago

Hello and thank you for the article. I found it while trying to find answers about my surgery 5 days ago. I awoke this morning with a resting pulse of 150.. deep breathing for about 15 minutes sitting and laying finally brought it down to 100 but then walking to the kitchen it immediately went back to 136. I had general anesthesia 5 days ago (Friday, today is Wednesday) and a Novasure/Myosure/D&C procedure to remove tumors, cysts, and the other gunk from my uterus). Since then I have had intermittent chest pain and will do deep breathing for about 10 minutes each time.. this morning was the first time I checked my heart rate. Normal resting for me is between 90-100... but feeling so exhausted and the random chest pain with rapid heart rate is scaring me a bit. Any suggestions?

Vera 2 months ago

I am supposed to have surgery to have my left ovary removed, but my heart rate is 45, and the cardiologist said it is not safe to have this procedure done, I am so nervous and confused, is general anesthesia safe for some one who has a low heart rate, and also I have high blood pressure, I am so afraid....

Amy W 7 weeks ago

My husband just had rectal surgery for 6hrs today. When he's awake his heart rate seems to be 60-75bpm; when he's starts to fall asleep tonight his rate drops to 45bpm. The nurse doesn't seem to be worried. When should we be concerned?

TLM 2 days ago

Hi there,

I realize I'm 'late for the party' but I have a question that concerns me. I recently had total hip replacement surgery, and of course the surgery itself went very smoothly, but......2 days after surgery I had A Fib which only lasted about 4 minutes, and a week later was severe enough to land me back in the hospital for a few days. It took the emergency room crew several hours to regulate my rhythm and blood pressure. I also have high blood pressure which is controlled by medication. While in the hospital the 2nd time (about a week after surgery) they ran about every heart and lung test known to modern medicine and found nothing wrong with the heart or lungs. Am now on a 'beta blocker' med to help control the rate and rhythm and am doing fine. I will probably need the other hip done at some point, but am now terrified of the surgery, because of this whole complication. Any suggestions? Maybe a 'local' anesthetic would be safer?

Thanks for any suggestions.

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