Dextrocardia

[Jinx]

Hey all

Anyone that reads Paramedicine 101 would have seen the article about a week ago in regards to Dextrocardia, found here: http://paramedicine101.blogspot.com/2009/08/dextrocardia.html.

I tried to get an answer in regards to defibrillating a patient with Dextrocardia from my uni lecturers but they weren't 100% sure, so hoping someone here might have a better idea.

From what I can tell it is possible to tell someone has Dextrocardia if they have a normal sinus however what I am trying to find out is if someone is in VF/VT firstly would it even be possible to know they have Dextrocardia? and secondly if it was/is possible to know they do have it or it is a witnessed arrest and you identify they do have Dextrocardia would you place you defib pads on the opposite sides to that of someone with normal heart placement?

Apparently only 1 in every 12,000 people have it so it's probably a slim chance I'll ever come across the situation, however it's always good to know

Cheers,

Jinx

 

[Melclin]

There would be no way to tell if they were in VF. By definition, there is no organisation to depolarisation in VF. All the axis polava that you'd use to figure it out in someone who had an organised rhythm doesn't exist.

As for VT, I'm not sure, so let me think out loud for a bit. I am sure that you would have to analyse it to such a degree that you would be wasting valuable time in an arrest, and given the prevalence of dextrocardia, its way more likely that you had just stuffed up in some way if you thought you were seeing a rhythm that represented it. But as you say, it's a hypothetical question of whether or not it's possible. I'd think that you would be able to. The vector of the VT would be uniformly different and you would imagine that it would be evident on the monitor. How though, I couldn't say, I've not looked at all that vectors stuff yet. Love to know though.

If for some reason you knew they had dextrocardia, yes, you put the pads on in the opposite configuration. The electricity has to pass through the heart, pure and simple. It's not going to do that if you put the pads on around the wrong way (the right way for a normal person). It make intuitive sense and as I understand it, it is the convention. However, there was a case study published in EMJ a while back about a person (who was dextrocardic) being successfully shocked out of VF in the normal configuration. In their discussion they said that there was nothing in the published literature that showed that either way was more successful...so who knows.

PS: I'm definately going into uni on Monday to stick a monitor on backwards and try and figure out a way of simulating dextrocardia in the lab. Any ideas (short of a backwards monitor and drugging myself into VT)?

 

[Jinx]

Apparently if you place your 12 leads incorrectly it can give you the same ecg reading as Dextrocardia and if you get this result you should first check your lead placement before you suspect Dextrocardia, so perhaps someone on here will be able to shed some light on how you can misplace the leads to replicate it?

When you see a negative QRS in lead I, and a positive QRS complex in aVR, you should first suspect misplaced leads. If they are placed correctly, dextrocardia should enter your differential.

So, if you ever have the idea that the ECG you are looking at, looks as if your leads are all reversed, maybe the heart is.

When defibrillating these patients, traditional pad placement should be mirrored to the right chest. Anterior/posterior placement should be just right of the mediastinum.

I guess that answers my question (pays to read ALL the article) Although I'm still curious to know what VT would show on the monitor? and I wonder if this would be what we would do in Australia? I guess it may be the case for Melbourne where they can work outside protocol so long as they can support their decision as opposed to NSW who can only work within the clinical guidelines no matter what?

 

[Melclin]

Apparently if you place your 12 leads incorrectly it can give you the same ecg reading as Dextrocardia and if you get this result you should first check your lead placement before you suspect Dextrocardia, so perhaps someone on here will be able to shed some light on how you can misplace the leads to replicate it?


I guess that answers my question (pays to read ALL the article) Although I'm still curious to know what VT would show on the monitor? and I wonder if this would be what we would do in Australia? I guess it may be the case for Melbourne where they can work outside protocol so long as they can support their decision as opposed to NSW who can only work within the clinical guidelines no matter what?

Yeah, but I'd just get a replica of a dextrocardic twelve lead NSR. I wanna see what it's like in VT.

Yeah we'd easy get away with it as long as we could pull out a reason why. Still, if that article in EMJ wasn't pulling my leg, there may not actually be any evidence that its a good idea. But it does make intuitive sense, and it was up until recently considered conventional practice in pts with dextrocardia as far as I can tell. That might be enough. In any case, I wouldn't worry about it. But its an interesting hypothetical.

 

[sdadam]

Dextrocardia can be one of a few types...

Dextrocardia (dextroposition) alone means that the heart is more on the right side of the thorax than the left, but does not necessarily mean that it is anatomically reversed.

Dextrocardia Situs Inversus, on the other hand means a true mirrored reversal of the normal anatomical position of the heart. Identified on an EKG most commonly as an extreme right axis deviation, positive deflection of the QRS in aVR, and reversed precordial QRS amplitude progression.

Two best differentials: limb lead reversal (LLR) or Dextrocardia (which do you think is more common). In Dextrocardia you will have inverse R waves, not so much with LLR, also Dextrocardia will have loss of voltage across the myocardium, LLR will not.

Finally it is worth mentioning Dextrocardia Situs Inversus Totalis in which all of the major organs of are in mirrored positions.

I think most of that was talked about in the article that you referenced, so about your questions.

If you have a PT which you are certain is a Dextrocardia Situs Inversus PT, then yes, you should both reverse your ECG leads and defibrillation pads.

This question really comes down to the much debated question of "How important is pad placement". And most research shows that it is actually quite important.

When defibrillating a PT, only a fraction of the energy delivered to the body actually transverses the myocardium. Ideal placement of electrodes for defibrillation and pacing is the anterior/posterior model (not the more commonly used upper right, lower left anterior model) this has to do with the fact that defibrillation is not accomplished with Joules.

I know, I know, we set Joules and then press shock. The truth of it is defibrillation is accomplished with CURRENT. An adequate amount of current must pass through the actual myocardium depolarizing a critical mass of it.

Energy (in Joules (J)) = Voltage * Current * Time

And

Voltage = Current / Impedance

Modern defibrillators Lifepack and Zoll, both are able to read impedance of the patient in order to deliver the most effective energy amount possible, they cannot however direct the current through the myocardium, that is up to YOUR pad placement!

Soooooo, we can see that there is no real way to decide the energy (J) delivered since we have no control over the impedance presented by the PT, The monitor makes it's best guess, usually rated +/- 5%, up to 50 Ohms of impedance (for Zoll).

Taking this all back to your PT with Dextrocardia, if you don't switch the pads can defibrillation still work?

Of course, you are just decreasing the CURRENT across the myocardium, so it is beneficial to mirror your pad placement.

You might even decrease impedance with poor pad placement but send the current through more non-cardiac tissue than you will with proper pad placement. Our goal is not Joules delivered to the PT, but Current across myocardium.

Note we don't SWITCH pad placement we mirror it, meaning you should have a pad on the left mid-clavicular and a pad on the right mid or anterior axilla, NOT the positive pad on the bottom and the negative pad on the top (Really you should stick with anterior/posterior placement, and just move to the right side of the chest and back instead of the left, but for some reason no one does this unless pacing, at least in San Diego)

Long story short, mirroring your pad placement in a patient with Dextrocardia will allow you to maximize CURRENT that actually transverses the myocardium, which is your money when it comes to being successful in restoring an organized rhythm.

HOWEVER, if you have a patient in vTach or vFib, there is no criteria for defining Dextrocardia. So if you don't know you don't know, no big deal.

Hope that helped clear things up for you brother!

Adam

P.S. There is some small observational research out there which suggests that in difficult to defibrillate vTach or vFib, which persists in a "viable" manner (i.e. not super fine vFib) reversal of the pads can sometimes prove effective in restoring an organized rhythm. (NOTE now I'm talking about switching the positive and negative electrodes, not mirroring placement from left to right).

The idea being that when shocking the heart TIME was just as important as voltage and current in the above equation. Research identified that 10ms was the best time, with defibrillation threshold initially dropping and then increasing after passing the 10ms mark. Zoll monitors are biphasic and shock from one direction for 6ms, then reverse to the opposite direction for the last 4ms. So you are changing the nature of the waveform by reversing the pads. (I don't know about the Lifepack waveform but I'd bet it's the same)

I'm not saying it will work, but if you are a few 360j shocks in and keep getting vTach, you need to try something different, at least try moving your pads to maximize current across the myocardium, and try reversing them.

Doing the exact same thing over and over again expecting something different is crazy right!?

So now you can do it, and if anyone asks just start talking to them about current across critical mass of myocardium, and they will stop listening and let you do whatever you want.

Hope that was interesting too!

 

[sdadam]

I just saw your second question about recreating a Dextrocardia ECG.

Just put the Right Arm Lead on the left arm, and the Left Arm Lead on the right arm.

You will get everything you get with Dextrocardia, EXCEPT you will most likely have positive R waves, Dextrocardia would not, AND you will most likely have a normal QRS voltage, Dextrocardia would be lessened. (Lots of monitors if encountering Dextrocardia in a 12lead will print out **Suspect Limb Lead Reversal**

I'll share a pretty humbling story from back in the day...

I was an ER tech at Tri-City Medical Center in San Diego County. I did a 12lead on a chest pain PT and switched the limb leads by mistake. The top of the 12lead read ***Acute MI*** etc. you know the drill. I didn't catch it (EMT-B at the time) and the Doctor didn't catch it. But when the cath-lab cardiologist got there (it was 3am) he caught it, and was PISSED. So long story short apparently limb lead reversal can cause a STEMI impostor ECG. Who knew....

 

[VentMedic]

I was an ER tech at Tri-City Medical Center in San Diego County. I did a 12lead on a chest pain PT and switched the limb leads by mistake. The top of the 12lead read ***Acute MI*** etc. you know the drill. I didn't catch it (EMT-B at the time) and the Doctor didn't catch it. But when the cath-lab cardiologist got there (it was 3am) he caught it, and was PISSED. So long story short apparently limb lead reversal can cause a STEMI impostor ECG. Who knew....

Bad lead placement and the inability to even recognize artifact caused Cath-lab Cardiologists to seriously doubt the future of one county's EMS STEMI program in Southern California. The Paramedics were only relying on machine interpretation and were clueless of any other factors due to poor initial training. I believe they now have gotten enough training to know what artifact is and how to properly place or apply the electrodes but still no education/training of what all those squiggly lines mean.

I believe this comment from a Southern California member on another thread sums it up.

Relax homeboy it's just a stepping stone job, it's not going to kill anybody if you have to waite and get a&p a little later.

 

[mycrofft]

Ask the mfgr.

Email the folks who make defibrillators.
Could an AED recognize it?
How common is it?

 

[sdadam]

An AED could not tell the difference, it would never know.

There is NO electrophysiological difference in ventricular tachycardia, or ventricular fibrillation of a Dextrocardia PT that can be identified on an ECG.

Again, you CAN NOT tell the difference if a PT is in vTach or vFib.

I have found sources that say Dextrocardia is as common as 1 in 100 people, and most agree that Dextrocardia Situs Inversus Is limited to between 1 in 10,000 to 1 in 12,019.

Strangely enough Dextrocardia Situs Inversus Totalis, actually a misnomer for Situs Inversus Viscerum, meaning "inverted position of the internal organs" (The heart being an internal organ so adding the word dextrocardia is redundant) is reported everywhere I saw to be of about the same prevalence as Dextrocardia Situs Inversus.

 

[piranah]

in my short career i have come across 2 pt with situs inversus....i had to place the limb leads mirrored along with the 12-lead...when i walked in she was telling me she had chest pain here..( pointing to R side of chest) i then found in my assessment she had this rare condition....reversed the leads and presto... i still have the assessment because i was on my ride time for my medic.....it was a good experience because my preceptor didnt say a word and was pleased to see that i knew to reverse the leads....also note that with situs inversus totalis everything is reversed.....also when you do anterior posterior pad placement you must place them more to the R side of the thorax....ALSO big one....when you intubate its the L mainstem bronchi so if you hear good L sided breath sounds just make sure its bilateral because it could be misleading (even though you should have good bilateral chest rise with equal breath sounds normally) just a note there..and with adenosine its the R AC for administration

 

[Melclin]

Bad lead placement and the inability to even recognize artifact caused Cath-lab Cardiologists to seriously doubt the future of one county's EMS STEMI program in Southern California. The Paramedics were only relying on machine interpretation and were clueless of any other factors due to poor initial training. I believe they now have gotten enough training to know what artifact is and how to properly place or apply the electrodes but still no education/training of what all those squiggly lines mean.

I believe this comment from a Southern California member on another thread sums it up.

Well thankfully we don't have machine interpretation here. Had a lot of success with straight to cathlab programs too for our IC medics. While you're at it, I need your thoughts.

Seeing as though the question has been pretty much answered and VENT is here, I thought I might bring up something thats been bugging me for a while. Maybe it could be discussed in tandem to any new developments on the dextrocardia front, especially seeing as though education has been brought up.

I have to confess, I'm losing the faith a little on the topic of education. Starting to get a little sick of learning so much about the medicine only to have it not matter. I love the medicine, and I want to be able to investigate it more deeply clinically and use that knowledge, but it seems useless for the most part in practice. I'm starting to find it difficult to see why I should explore all the complexities of cardiac cellular physiology if it makes no difference to my treatment at all. When it comes down to it, it seems like I'm still just ganna be a taxi driver for sick people and occasionally and agent of ACLS. While I might understand more of my pt's pathophysiology than a lesser educated medic, what difference does that make given that my treatment will still essentially be sitting next to them in the back of the truck while we drive to hospital. Why bother understanding a host of different players in the inflammatory cascade in shock when all I'll be doing is pumping x amount of fluid into them, slapping on a O2 mask at a *fixed* 8 litres and, you guessed it, driving them to hospital.

My enthusiasm for knowledge is neither shared by most of my peers nor, it seems, needed to fulfill our role. I get dirty looks from class mates who wonder why I read medical journals in my spare time. To be honest I'm starting to think maybe they're right...whats the difference if we all think CPAP pushes fluid back into the blood, and lignocaine numbs the heart (we can't even use it, its an IC drug). It doesn't seem to change when or how we give treatment to any great extent, as long as well informed people make the guidelines and us stupid roadies follow them with some degree of reasonable common sense adaptation to different situations, then no harm, no foul.


I don't actually believe that, but I'm starting to wonder....We learn all about a,b,c,d,e,f,g,h,i,j,k and l; then we get to what we actually do about it. "well for A we do x, for B...well we do X, for C we do X but a little quicker ad infinitum. I need to be reminded why I, when I get on the road and slap 8 litres on every idiot with a broken toe (hyperbole, but you get my point), how I will be using all this education. Three years at university to essentially have a scope of practice vaguely equivalent to what you would call an EMT-I.

 

[sdadam]

I feel your pain my friend.

But we are not doctors.

Will knowing the details of cellular physiology make a difference in your patient care? Maybe not on every call no, but ultimately you will have a more in depth knowledge of pathophysiologic mechanisms of injury and disease. You will be more adept at recognizing early and minute signs of changes in your PT. And will be better prepared to anticipate changes in PT conditions before they happen based on present signs and symptoms.

Your PT care WILL ultimately benefit from your more advanced knowledge. It just isn't always in the dramatic TV style way we wish it would be. You will catch things that other medics would have missed.

Will it always change your treatment? No, not always, but that comes back to the whole we are not doctors thing. Paramedic education teaches medics to know just enough to be dangerous, most think they could work without protocols, but are so far from being able to safely do that it's laughable.

For instance if there were no protocol for pain control specifying what medication to give, and how much, it would be left to a medic to decide between the hundreds of analgesics available. Most barely understand the ONE that their agencies carry. They are comfortable with what is in there scope, but would be lost without it. And the majority rely on anecdotal information from other medics, or their own experience (this happened once, so it must always happen) rather than incorporating research, and ongoing education in to their practice.

If this truly frustrates you, it might be time to look in to PA, or MD school instead. A medics primary goal will always be to provide only care that will decrease morbidity and mortality by getting it on board quickly, or decrease PT discomfort during the ride, if it can wait till the MD is there, it will.

And rightfully so, there is a reason becoming a doctor is the long, tough process that it is.

 

[Jinx]

Hey guys just got a response to my questions on paramedicine101 with similar answers to what has already been discussed here, thought I would post it up for those still interested.

Cheers,

Jinx,

Sorry for the delay...

... Yes, as I stated, put the pads on the opposite side if you know they have dextrocardia.

If they have V-fib, it may be impossible to discover the history of dextrocardia without someone actually telling you they have it.

I am sure there is a way to tell, if they are in V-Tach. I just don't know how, since V-tach can present with an extreme axis deviation.

Remember, it would be pretty uncommon to find a patient in arrest with this condition. Anterior/posterior placement should work, even if you are slightly left of the main mass of the heart.

 

[medicnick]

Hi guys,
I have had a dextrocardia patient and have a learning case about the topic. We have discussed it before on the EKG Club several times but it is an interesting topic because it is something different.

Not sure if you all got your questions answered or not?

Cheers,
Nick

Hey guys just got a response to my questions on paramedicine101 with similar answers to what has already been discussed here, thought I would post it up for those still interested.

Cheers,