Cardiac question

[rhan101277]

In class last night my instructor made the comment that if you treat a right sided MI the same as a left sided MI you will kill the patient. I wanted to know if anyone could expand on what he was saying.

Also, I am correct in saying that when using a 3-lead you will not be able to tell if its right sided or left sided, just that there is a MI going on.

 

[Shishkabob]

What he's saying is that with a RMI, the right ventricle is being infarcted and getting weaker. The RV is preload dependent, so when you load up on morphine and nitro, it gives less fluid to an already weak ventricle that struggles to push the fluid it has already and the Frank Starling law says that less fluid with a weak heart means less cardiac output. You pretty much bottom out their BP.


The treatment for an RMI is to do a fluid bolus of NS as to 'prime the pump' so that when you give vasodialators, the Starling effect is still in action and the RV can still feed the LV. So ALWAYS give a fluid bolus for an RMI before giving nitro / morphine.




Some medics are in the camp to never give a vasodaolator to an RMI, while others (myself included) would as long as you do the fluid bolus. If you don't give nitro / morphine then the ischemic and injured tissue will continue to infarct and you just made a bad situation worse.





As for telling if it's a RMI, you'll typically need a 12-lead EKG and then do V4r. It's generally safe to assume that any inferior infarct is probably affecting the RV as well, so treat as such.

 

[MrBrown]

Your instructor is right, you're going to do some harm to an RVF or RVI patient if you follow a generic chest pain approach which means loading them up on GTN and morphine

Right ventricle infarct cannot be seen with 3 leads but its going to hopefully be rather obvious; cardiogenic shock, JVD, pedal edema etc

I don't really believe GTN has a role in infarct and as such am dubious of anyboy using it because

1) For right sided infarcts it will lower cardiac output even more, worsen perfusion state and exacerbate the fluid mismatch and cardiogenic shock or dump the peri-shocked patient down the drain

2) It has no analgesic or thrombolytic properties

3) GTN is designed for angina, which is a different pathology than in infarct

But having said that morphine is not really an effective treatment either but does provide good analgesic properties.

The mainstay of treatment (here at least) for an RVI/RVF is aspirin for infarct and small fluid challenges to try and get pressure up.

Intensive Care Paramedics might be able to get away with flogging the ticker along with some adrenaline but it's not in our procedures per-se

 

[TomB]

I think Linuss covered it pretty well. I wrote a 3-part series on right ventricular infarction you can find here. I personally find the "you'll kill your patient" line to be a bit over-used in EMS. I reserve that line for those occasions where someone wants to give Verapamil to VT.

Tom

 

[piranah]

I would not give NTG to a pt with a R sided MI. but thats how i was taught. the way i see it someone could have a aggressive action with nitro causing you to give a good amount of fluid. and if the nitro doesn't work you just added however much fluid to a pt who is not going to start backing up systemically. This pt needs a cath-lab not a paramedic.but also remember the leading cause of R sided failure...is L sided failure. And about the whole 3 lead thing...you should never only do a 3-lead 12lead is the only way to DX a STEMI.

 

[Shishkabob]

I'm trying to figure out why MrBrown said that vasodilators don't help in an MI?? Or how the effect that Morphine has on Catecholamine release isn't a big help either?


Did I read what he said wrongly?

 

[MrBrown]

I'm trying to figure out why MrBrown said that vasodilators don't help in an MI?? Or how the effect that Morphine has on Catecholamine release isn't a big help either?


Did I read what he said wrongly?

I didn't say GTN doesn't help but I believe the balance of risk vs benefit is in favour of not using it.

On the one hand the vasodilatory effect may improve myocardial oxygenation and reduce M&M however you have to weigh that against the risks associated with decreasing cardiac output and the problems it will cause.

Morphine may have some benefit as an anticatecholaminic in that it should have a negative chrono and inotropic effect which may have some benefit. Although this may be of use we must also consider the vasodilatory effect of moprhine.

For a classic RVI or RVF patient who is shut down and shocked our guidelines strongly caution against using GTN and morphine for the reasons I have outlined.

I won't be reaching for them in a hurry if I come across an RVI or RVF patient any time soon. Having said that if the patient is having significant chest pain, I wouldn't not try a little morphine in 1mg increments but we also have the option of inhaled analgesia.

 

[Shishkabob]

Which is why you give a saline bolus before giving drugs that decrease preload.

 

[TomB]

I would not give NTG to a pt with a R sided MI. but thats how i was taught. the way i see it someone could have a aggressive action with nitro causing you to give a good amount of fluid. and if the nitro doesn't work you just added however much fluid to a pt who is not going to start backing up systemically. This pt needs a cath-lab not a paramedic.but also remember the leading cause of R sided failure...is L sided failure. And about the whole 3 lead thing...you should never only do a 3-lead 12lead is the only way to DX a STEMI.

The patient needs a cath lab and a paramedic. There's a difference between acute right-sided heart failure and chronic heart failure. In the case of a proximal RCA occlusion, the cause of right ventricular failure is not left ventricular failure, but acute myocardial infarction. Aggressive fluid therapy is indicated for these patients. It's totally appropriate and not at all dangerous. If they "back up" it's not going to be in the lungs. Maintaining coronary perfusion pressure is what matters for these patients until the problem is resolved. I agree with NTG after fluid therapy for two reasons. First, NTG is a potent coronary vasodilator and some patients have collateral circulation that may be cardio-protective. Second, coronary vasospasm often accompanies acute STEMI, and in rare cases can even be the cause.

Tom

 

[alphatrauma]

Nitro can be titrated, provided the BP is sufficient... and I would hope clear lung sounds would be confirmed before any aggressive fluid administration (didn't see any mention of it).

I'd have 2 IVs in place

 

[rhan101277]

This is another good reason to do a proper assessment and even better reason not to be a cookbook medic.

The protocols tell you how to treat chest pain, but you still need to be a paramedic and do a pre-hospital diagnosis.

We just started on cardiac, so I hope I don't sound un-educated on the subject. I am familiar with all of the anatomy and electrical, but still need to be taught about EKG.

 

[redcrossemt]

The patient needs a cath lab and a paramedic. There's a difference between acute right-sided heart failure and chronic heart failure. In the case of a proximal RCA occlusion, the cause of right ventricular failure is not left ventricular failure, but acute myocardial infarction. Aggressive fluid therapy is indicated for these patients. It's totally appropriate and not at all dangerous. If they "back up" it's not going to be in the lungs. Maintaining coronary perfusion pressure is what matters for these patients until the problem is resolved. I agree with NTG after fluid therapy for two reasons. First, NTG is a potent coronary vasodilator and some patients have collateral circulation that may be cardio-protective. Second, coronary vasospasm often accompanies acute STEMI, and in rare cases can even be the cause.

Tom

+1.

Paramedics are always needed.

Nitro is indicated after fluid therapy is initiated.

 

[alphatrauma]

We just started on cardiac, so I hope I don't sound un-educated on the subject. I am familiar with all of the anatomy and electrical, but still need to be taught about EKG.

The right-sided 12 lead will be the order of the day. ST elevation in (R) 3-6 V leads will indicate possible/suspected RMI

 

[18G]

No, a 3-lead will not be able to diagnose any type of MI not just a right sided. However, if your doing a 3-lead and see elevation in lead II (which looks at the inferior portion of the heart) you should raise your suspicion of an inferior wall MI. Inferior wall MI has great potential for right ventricular involvement. Its not a specific finding but if all you have is a 3-lead its something to consider and watch out for.

 

[Tal]

What he's saying is that with a RMI, the right ventricle is being infarcted and getting weaker. The RV is preload dependent, so when you load up on morphine and nitro, it gives less fluid to an already weak ventricle that struggles to push the fluid it has already and the Frank Starling law says that less fluid with a weak heart means less cardiac output. You pretty much bottom out their BP.


The treatment for an RMI is to do a fluid bolus of NS as to 'prime the pump' so that when you give vasodialators, the Starling effect is still in action and the RV can still feed the LV. So ALWAYS give a fluid bolus for an RMI before giving nitro / morphine.




Some medics are in the camp to never give a vasodaolator to an RMI, while others (myself included) would as long as you do the fluid bolus. If you don't give nitro / morphine then the ischemic and injured tissue will continue to infarct and you just made a bad situation worse.





As for telling if it's a RMI, you'll typically need a 12-lead EKG and then do V4r. It's generally safe to assume that any inferior infarct is probably affecting the RV as well, so treat as such.

the MDA protocol forbids nitrates to a right wall MI

 

[MrBrown]

Aggressive fluid therapy is indicated for these patients. It's totally appropriate and not at all dangerous. If they "back up" it's not going to be in the lungs. Maintaining coronary perfusion pressure is what matters for these patients until the problem is resolved. I agree with NTG after fluid therapy...

You may be right however I am still dubious about GTN in these patients even if load them up on fluids. I did go out and find two articles which support the use of intravenous nitrates in these patients, see (1) and (2).

This is quite different from the good ole ambo trick of using the little red squirty bottle of sublingual GTN because intravenous nitrates can be controlled more precisely.

Here giving sublingual GTN for things other than chest pain associated with angina has basically been banned because large falls in blood pressure can occur and what the hospital does in one form may not extend to what is done in the back of the truck with limited monitoring and intervention capabilities.

(1) http://www.ncbi.nlm.nih.gov/pubmed/6407314

(2) http://www.springerlink.com/content/q4p5v41652241175/

Nitro can be titrated, provided the BP is sufficient... and I would hope clear lung sounds would be confirmed before any aggressive fluid administration (didn't see any mention of it).

I'd have 2 IVs in place

I would take it for granted that checking lung sounds would be part of standard of care but ..... you never know eh, where is a three month tech course gone wrong wondermedic when you need one?

Again, call me niave but the lowest dose of GTN we can give is 0.4mg SL (one squirt of the ubiquidos little red bottle) and I'm pretty sure (there's good evidence for you!) that when the hospital talks about titrating nitrate they are referring to IV nitrates in micrograms per hour (mcg/hr).

I've seen people flake out on 0.4mg and just drop like God himself struck them down.

Hmmmm ..... interesting.

 

[redcrossemt]

This is quite different from the good ole ambo trick of using the little red squirty bottle of sublingual GTN because intravenous nitrates can be controlled more precisely.

We use sublingual tablets, but others use spray, and yet others use paste.

I think we'll all agree that nitro is best controlled intravenously, but I think that sublingual doses given with close monitoring are well within the current standard of care and of benefit to most chest pain patients, especially when coupled with prior IV fluid therapy when right-sided infarct is suspected.

Do note that I'm an advocate of many services, especially those with longer transport times to a PCI-capable facility, carrying intravenous heparin, nitroglycerin, and thrombolytics.

 

[usalsfyre]

IV NTG is the bee's knees fort his type of patient. Much more precise control than dumping 400mcg under the tounge that you can't get back.

 

[piranah]

I must have not really written it clear..i never can type.. but anyway I was just correlating the similarity in how you would not want to give nitro to someone with R sided failure why would you give nitro to someone with a R sided MI which will lead to R sided failure..I do understand your point of view though. It was ingrained in our heads up here to never give nitro to a R sided MI...and the idea of needing a paramedic..obviously they do but I was trying to get the idea through that sometimes we can do more harm than good and sometimes passive medicine is better.

 

[zmedic]

Nitro has not been shown to improve mortality in MIs, so I don't see the big push to give it, especially if you have a concern such as a right sided MI. To those who say give as long as the pressure is okay, the problem is that you can kick their cardiac output really quickly. So you might think "the patient is 110/80, I can give nitro no prob" and the next thing you know they are 80/40 and obtunded.

I think you are asking for trouble giving nitro to a known right sided MI, better to be giving beta blockers if in protocols since that saves lives. That and ASA.