The “Hot Shot” : A Layman’s Approach to Myocardial Protection

A Salient Point from a Perfusionist:

“I will give one good example of how a warm/hot shot worked for us. We finished up a normal 4 banger and before doing the proximals with the cross clamp on we routinely give a short hot shot, actually its room temperature shot, but I digress. The clamp was removed, calcium given….nothing.

The patient started to fibrillate and we shocked several times, gave Xylocaine, shocked some more, still fibrillation continues. I suggested to rearrest the heart with warm cardioplegia, this time at 37 degrees. We gave plegia at 1000 cc’s then washed it out with just blood for 200 cc’s and popped the clamp. The heart started to beat in NSR. We have done that on two other patients and had the same result. I am a believer in the hot shot.”

Hoser

Let’s Give A “Hot Shot”

Ah yes.  The rare but not unanticipated request for a “Hot Shot” came up on the final leg of an aortic root replacement.

So depending on your cardioplegia circuit, and the point in surgery, a few quick but easy steps and decisions need to happen.

The first question that needs to be answered

Is what the the composition of the cardioplegia is-  in relationship to the operation.  Are you on the front end of an MI and need to give a quick retrograde dose to mitigate the damage from acute ischemia? 

Or is it toward the end of a long case- and the intent is to wash out metabolites from intermittent pelgia dosing?

In other words- is it straight blood- or a K+ depleted, nutrient enriched- 4:1 mix?

The second question that needs to be answered

How are you going to get it warm and deliver it?

Do you have a separate heater cooler for your cardioplegia circuit- and if not- what is your plan?

Tepid Retrograde Blood Cardiplegia

Anyway, that’s what I was going to deliver, and no- I have a simple circuit (due to out national K+ shortage) requiring me to switch away from the very versatile MPS system (Quest), to a very reliable coiled system (MP4- Terumo).

So here are the steps:

Clamp out your cardioplegia source…

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Remove your 4:1 plegia line from the roller-head…

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Remove your Plegia coil from your ice bucket- or cooling source

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Set your cardioplegia to recirculate- and slowly warm to patient blood temp …

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Start delivery when warm- or at least Tepid…

Editor’s Note:

I know this isn’t exactly rocket science- and it is not intended to be anything more than what it is.

A simple method for a simple fix.  A Hot Shot before the X-Clamp comes off.

I don’t think that this will lead to an invitation to speak at a meeting LOL.  🙂

Some Academics:

Click image above to view source article…

Abstract:

Intermittent antegrade cold blood cardioplegia is the predominant method of myocardial protection, but recent studies suggest that warm or tepid blood cardioplegia may improve the return of myocardial metabolic and contractile function. Data were collected prospectively on 1,533 patients undergoing cardiopulmonary bypass in a single surgeon’s practice.

The use of intermittent antegrade cold (4°C) blood cardioplegia in 951 consecutive patients from September 1994 to November 1997 was compared with intermittent antegrade tepid (28°C) blood cardioplegia in582 consecutive patients from July 1998 to July 2000.

The two groups were similar, but the symptom class was more severe andthere were more redo and combined procedures and more operations within 7 days of myocardial infarction in the tepid group. Significant clinical benefits identified in the tepid group included reduced usage of intraaortic balloon pumping postoperatively (4.4% versus2.2%) and reduced incidence of postoperative atrial fibrillation(25.7% versus 20.6%).

There was no significant difference in mortality, perioperative myocardial infarction, cerebrovascular events, or use of inotropics between the groups. Intermittent tepid blood cardioplegia is clinically appropriate and safe to use in patients undergoing cardiac surgery.

0 thoughts on “The “Hot Shot” : A Layman’s Approach to Myocardial Protection

  1. I will give one good example of how a warm/hot shot worked for us. We finished up a normal 4 banger and before doing the proximals with the cross clamp on we routinely give a short hot shot, actually its room temperature shot, but I digress. The clamp was removed, calcium given….nothing. The patient started to fibrillate and we shocked several times, gave Xylocaine, shocked some more, still fibrillation continues. I suggested to rearrest the heart with warm cardioplegia, this time at 37 degrees. We gave plegia at 1000 cc’s then washed it out with just blood for 200 cc’s and popped the clamp. The heart started to beat in NSR. We have done that on two other patients and had the same result. I am a believer in the hot shot.

    1. Precisely what I am talking about. You have to RAP your CP Circuit where as using Quest you simply “run” till red. Albeit accomplishing the same task of not exposing the patient to unnecessary hemodilution. Low tech vs. high tech…same end result but more room for operator error? You are adding a step necessary for your system but “engineered out” in other systems.

      Just thinking through delivery systems and what should, would, could be SOP if it even needs to be addressed. Most will say no undoubtedly. I agree that recipes vary widely with acceptable results in the respective institutions. But how are they being delivered to the Ao/ostia/CS and does it matter?

      1. Since I’m not familiar with the Quest, I cannot say that it is easier to RAP vs the older method, but it sounds to me that Rapping with either is the same. When I RAP my ‘low tech’ model, I use the same forward flow method. As far as ‘addressing’ your concerns about what method to deliver CP to the patient, I doubt seriously that there is a perfect method. I have been using my antiquated system with plegesol for nearly 35 years with what I consider fantastic results. Only two VADS in those 35 years and one of those was a failed heart transplant where we were on bypass for 24 hours while trying to find a new heart. Now of course that is not to say that we haven’t had intraoperative mortality, that would be a miracle, but meticulous usage of cardioplegia after each graft and or jump-graft with blood cardioplegia has been the savior of cardiac surgery. I remember when the surgeons from the Attila the Hun school of surgery who used to use ischemic arrest when working on the heart. The surgeon had to be fast in their technique. We did many IABP’s and Circ Assist during those era’s. The best programs today in the US have surgeons who are quick but careful and have a handle on myocardiall protection with a good post-operative care regimen. Its not any more complicated than that.

  2. I would like to know the current “standard of practice” for CP delivery. For example I have never used the “coil” recirc sets. I have used every 4:1 set made and also many of my homemade devices and various mixtures of blood and crystalloid recipes I have mixed myself. There seems to be literature debating del nido vs. st Thomas etc BUT…how are you delivering it? Equipment-wise?

    1. I doubt that you will find two SOP’s that are the same. Standardization of cardioplegia changed after the many 1980’s papers written that started the blood cardioplegia mania that switched most users from crystalloid CP. I use a “home brew” kit that uses a drop-in coil and it also recirculates so I can RAP the set once the cannula is in. There are so many successful programs using so many techniques that I’m sure we would marvel at some of the sets and solutions. Frankly, I think that blood cardioplegia has been a God send to cardiac surgery.

      1. I hear what you are saying but HOW is it delivered…North American Centers, 50/50%/ 80/20 95/5 using “low” tech vs “high tech”…. spectrum being (bag-roller-ao circuit) to Quest System.

        1. Well I kinda indicated that there probably as many different methods of delivery and settings than there are perfusion groups. Like I said, there is no defined SOP for cardioplegia. :Maybe our “group leader” should take a poll for you. In my practice I use a 4:1 blood set that is a bastardization of the old Sarns ICDS system of the 70’s and 80’s. I use a recirculation system that I can RAP. My plegia solution is Plegesol as my base and I add some Mannitol and extra K and some HCO3. But there again, plegia formulation is probably more diverse then are the sets being used to deliver it.

  3. Hot shot’s shouldn’t be brain salad surgery, it can be adapted in just about any circuit that has a drop in coil or separate heat/cold source available. I have been using a drop in coil, in one form or another, in my set for many years. I use the CSZ as my heat/cool source by dropping the coil into either of the two reservoirs. I believe the initial hot shot is more important that the second. The reason being primarily by allowing the cardioplegia to be distributed evenly in the coronaries before you hit it with the cold. The cold will cause what? Vasoconstriction. By placing the coil into the cold side after the hot shot, the temperature will SLOWLY cool also helping with the distribution of cardioplegia before the coronaries start to constrict. I firmly believe that K is more important than cold. Here is my theory: We used to measure myocardial temperatures with using this technique but we cooled the heart down to 8-10 Degrees C, that is cold. By doing that, it took a long time for the heart to come back strong enough to come off of bypass once we finished (and we saw a lot of PO atrial fib) we did not do hot shots in the early days. We then stopped measuring temps and just gave cardioplegia by volume, what that did, indirectly, addressed the high K’s we got with freezing the heart with buckets of cardioplegia. Anyway, during the halcyon days of cardioplegia papers in the 80’s, we decided to use the hot/cold/hot shot–using volume only–and started to have hearts that came back in NSR routinely as soon as the clamp came off. By changing our technique the old set would not work since it was a set that had to have a device to deliver it (Sarns ICDS) and we had no easy way to warm the blood. We redesigned the set, got rid of one more machine in the room and solved a problem all at the same time.

    In the post above concerning the fibrillating heart and re-arresting of the heart, we used the same cardioplegia solution we used during the case. We had to add more K to the take down dose, but that is all.

    I know we all have had patients that just would not arrest for some reason, either it be due to undiagnosed AI, or the coronaries are so tight that you just can’t get enough cardioplegia down the line to stop the heart. If you are not going to try retrograde either due to not having catheters or the surgeon is not familiar with the technique, warm cardioplegia is the only way you can have a chance in stopping the heart. Continuous warm cardioplegia is a valid technique, it may not be ideal for everyone, but there are many surgeons who use it, even for valves, and have good results. My point of bringing continuous warm blood cardioplegia into the discussion was that it was first described back in the ’80’s during those halcyon days of cardioplegia papers. It would be a good idea to review those papers including aspartate and glutamate–which I have used and loved–when you had an acute MI or a crash and burn from the cath lab. Long live Gerald Buckburg!

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