Here’s an interesting video brought to you by Pro EMS Center for MEDICS in Cambridge, MA. Clearly, this physical exam wasn’t gleaned from a paramedic textbook. I personally think paramedics need to do a much better job when it comes to performing a physical exam. Auscultating valve sounds in the field? Not realistic, IMHO. But I give them an A for effort!
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The recent case on Burned-Out Medic’s blog has reminded me how much I’ve benefited from the study of implantable medical devices.
As I stated in my interview with EP Lab Digest:
“As for the nuts and bolts of cardiac rhythm analysis, it’s the realization that the heart has two rhythms happening at the same time, one atrial and the other ventricular (hopefully in a 1:1 relationship with a functioning AV node). This is probably why studying implantable medical devices has deepened my understanding of heart rhythms. After all, pacemakers function by offsetting defects in the heart’s electrical conduction system.”
We are often faced with patients who have implantable medical devices, and the indications for these devices are continually expanding. (See also my series on Ineffective or Inappropriate ICD Shocks.)
There are a lot of myths out there about paced rhythms. The worst of all is this one.
“It’s impossible to identify acute STEMI in the presence of a paced rhythm.”
This myth is so pervasive that I’ve witnessed situations where paramedics didn’t place the patient on a monitor because the patient had a pacemaker!
In the first place, you can use Sgarbossa’s criteria to identify acute STEMI in the presence of a simple paced rhythm (where the pacing lead in the apex of the right ventricle which is typical). I’m adding that qualifier because modern bi-ventricular pacemakers are an entirely different animal.
Secondly, you should always capture a baseline 12-lead ECG, regardless of what kind of rhythm is present! How else can you look for changes on serially obtained ECGs? Changing ST-segments and T-waves suggest the dynamic supply vs. demand characteristics of ACS!
Even when I worked on the Critical Care Stepdown unit as a cardiac monitoring technician, it was unusual for anyone to bother selecting whatever lead (and gain) was required to identify the underlying atrial rhythm of a paced rhythm, which is the key to understanding a pacemaker’s behavior. By behavior I mean the pacemaker’s programming and timing cycles.
The best interpretation you would generally get is “single chambered paced rhythm” or “dual chambered paced rhythm”.
In the field, we are often blinded to the type of pacemaker and how it is programmed (although there’s a good chance the patient carries an I.D. card — you can always ask to see it). However, if you are observant, you can make some pretty good assumptions about whether or not the patient has a pacemaker and whether or not it’s functioning properly.
Most modern pacemakers are DDD pacemakers according to the NBG pacemaker code.
Even though the chart shows five columns, in clinical practice the first three columns are the ones most often mentioned. So a DDD pacemaker may actually be a DDDRO pacemaker. We’re just discussing the basics here.
So that means that a DDD pacemaker is capable of pacing and sensing both the atria and ventricles. For our purposes that means that a DDD pacemaker is capable of atrial tracking. In other words, if the patient’s sinus node is firing within acceptable parameters, the atrial pacing lead will not pace. Rather, the pacemaker will track each P-wave and ensure it is followed by a QRS-complex. If not, the pacemaker will provide one.
Let’s go back to the case on Burned-Out Medic’s blog. The first ECG appears to show 3AVB with wide complexes. The wide complexes, it turns out, are paced. But there is no relationship between P-waves and paced QRS-complexes. So we know this pacemaker is not functioning effectively in DDD mode, because it’s not “tracking” P-waves and providing QRS-complexes after the P-waves to take advantage of the “atrial kick”.
However, we can say that the ventricular pacing lead is functioning and has “capture” which is a good thing for this patient, because there is no apparent intrinsic ventricular activity!
EMS is called to the residence of a 90 year old female who awoke to an “uncontrolled bowel movement” that corresponded with sudden onset abdominal pain.
On EMS arrival, the patient is alert and oriented to person, place, time, and event. She has a grimace on her face and appears acutely ill.
When asked the exact location of her pain she points to the epigastric area.
Past medical history: “Cardiac problems”
Medications: Numerous (but not available for the case study)
Vital signs are assessed.
Resp: 18 shallow
Pulse: Too rapid to count
BP: 118/60
SpO2: 96 on RA
The cardiac monitor is attached.
The patient is immediately loaded on the gurney and relocated to the back of the ambulance where she is placed on oxygen, an IV is established, and the combo-pads are placed.
Breath sounds are clear bilaterally.
A pacemaker can is noted in the upper-left chest.
A 12-lead ECG is captured.
At this point the patient’s skin appears grayish, pasty, and moist. Her level of consciousness is diminished and she stops responding to verbal stimuli.
What should the paramedic do next?
*** Update 06/11/2010 ***
Since everyone seems to agree synchronized cardioversion is warranted, and because I’m going out-of-town for a little while, I’ll go ahead and share this update today.
The patient immediately became more responsive and kept her eye on the treating paramedic for the remainder of the transport.
Here is the 12-lead ECG captured on arrival at the hospital.
The only other information I have about the case is that the patient was bolused with amiodarone in the emergency department and was admitted to the ICU where they had trouble maintaining her blood pressure over the next 24 hours.
I have no idea whether or not the amiodarone contributed to the blood pressure problem, but it’s worth remembering that amiodarone lowers the blood pressure, which is one of the reasons I’m hesitant to give it in the field when I have a patient who is doing well after being resuscitated from sudden cardiac arrest.
Here is the history of present illness recorded by the physician at the time of the patient’s arrival in the emergency department.
“This 67-year-old male presents via EMS for evaluation of weakness, dehydration and one episode of nausea/vomiting. The symptoms began after approximately one hour of jogging this morning. The patient did not eat breakfast and he did not take his blood pressure medicine. The patient reports that he drank some Gatorade prior to contacting 9-1-1. He denies any chest pain or shortness of breath and reports he has otherwise been feeling well since a hip replacement three months ago. An IV was established by EMS and the patient is feeling improved at this time.”
Imagine their surprise when they recorded this 12-lead ECG.
The treating paramedic had placed the patient on the monitor, but no 12-lead ECG was captured in the field.
Here is the rhythm strip retrieved from the archives of the LP12.
Here is the exact same rhythm strip retrieved from ePCR with the low frequency / high pass filter set to 0.05 Hz (diagnostic mode).
Fortunately, the interventional cardiologist was at the hospital making rounds. The patient was fast-tracked to the cath lab where angiography revealed 100% occlusion of the distal RCA. The door-to-balloon (D2B) time was excellent.
Before – distal occlusion of the right coronary artery (RCA)
Balloon inflation
After successful stent placement
What is the take-home message for EMS professionals?
See also:
Here is the update to 81 year old male CC: “Cold and shaky”
The patient was sent to the cardiac cath lab where angiography revealed 100% occlusion of the right coronary artery (RCA). A stent was successfully placed and the patient is doing well.
Before
Balloon inflation
After successful stent placement
Diagnosis: Acute Inferior ST-Elevation Myocardial Infarction
I’d like to thank everyone for the great comments on the most recent “rhythm challenge”. This turned out to be a more interesting rhythm strip that I thought!
I’m going to break this down using some standardized steps that I follow for difficult rhythm strips. When I look at a strip, the first thing I ask is, “What is the underlying rhythm?”
What do I mean by that and how do I make that determination?
I mentally remove the abnormalities to see if there is a “normal” rhythm underneath!
How would that work for Rhythm Challenge #4?
In my mind, I make the rhythm strip look like this:
Now I can see the “underlying rhythm” which appears to be sinus rhythm with a normal PR-interval and LBBB morphology.
The next thing I noticed about this rhythm strip is that it’s “regularly irregular”.
It shows a fairly elaborate repeating pattern (repeated at least once anyway).
Next I zero in on the premature complexes with identical QRS morphology to the underlying rhythm.
We know these aren’t PVCs because the QRS morphology doesn’t change. So these must be either PACs or PJCs.
In the field I don’t bother taking the analysis any farther because it doesn’t change anything. But when I worked inside the hospital we would indulge ourselves by trying to solve the mystery!
At first glance, they appear to be PJCs because there are no obvious ectopic P-waves. However, a careful examination of the preceding T-waves tells the tale.
This is what it means to develop a “trained eye” in electrocardiography.
In lead II, you can see a “bump” on the T-wave and in lead V1 the apex of the T-wave is narrower and slightly taller. The most likely explanation is that an ectopic P-wave is “buried” in there, which makes these premature complexes PACs.
Next I move on to the “abnormal” QRS complexes (abnormal QRS morphology in comparison to the underlying rhythm).
Initially, I just assumed these were PVCs (perhaps fusion complexes since they are preceded by a P-wave).
However, some very interesting comments here and on the facebook fan page have made me consider other possibilities.
I still think these might be PVCs, but it’s also at least remotely possible that these abnormal-looking QRS complexes are the result of Ashman’s phenomenon or an accessory pathway.
Statistically speaking, an accessory pathway is the least likely (in my opinion), but it’s interesting that the PR-interval is “short” and QRS complex in lead V1 shows a slurred upstroke consistent with a delta wave. Good eye, Adam!
I was also fascinated by Peter Shin’s comments on the facebook fan page. He raised the possibility that these complexes represent aberrant conduction secondary to Ashman’s phenomenon. I hadn’t considered that possibility, because I normally associate Ashman’s phenomenon with atrial fibrillation.
For those who have never heard of Ashman’s phenomenon (or need a refresher) it’s abnormal ventricular conduction that follows a sudden “long” cardiac cycle. As you can see, these abnormal complexes follow a “long” cycle.
Consider this quote from the Ashman’s Phenomenon article at WebMD’s emedicine:
Ashman phenomenon is an aberrant ventricular conduction due to a change in QRS cycle length. In 1947, Gouaux and Ashman reported that in atrial fibrillation, when a relatively long cycle was followed by a relatively short cycle, the beat with a short cycle often has right bundle-branch block (RBBB) morphology.1 This causes diagnostic confusion with premature ventricular complexes (PVCs). If a sudden lengthening of the QRS cycle occurs, the subsequent impulse with a normal or shorter cycle length may be conducted with aberrancy.
The only thing creating cognitive dissonance for me is the part about RBBB aberrancy. If Ashman’s phenomenon occurs in a patient with baseline LBBB, shouldn’t the result be a “dropped” QRS complex? After all, if left bundle branch is blocked, and the right bundle branch is still refractory, what’s left to conduct the impulse to the ventricles?
I don’t have all the answers, but this is why it’s good to think in terms of differentials when you work in the humbling field of medicine!
Here are my closing comments from the NAEMSP Dialog group discussion “EMS Role in Reducing the Symptom to Reflow Interval for AMI”.
I think it’s important that we finish building regionalized STEMI systems in every state, and do our best to help ensure that our patients receive evidence based therapies, no matter where they live. Once these systems are up and running, they are fine-tuned, and we have a better understanding of where we want to be in terms of “false positives” and “false negatives” (including standardized definitions) we will be in a position to extend these systems to include select high-risk NSTEMI patients, if and when the evidence supports treating them the same as STEMI patients (immediate reperfusion as opposed to “early invasive therapy”).
The most important step for my EMS system (and many other EMS systems throughout South Carolina) was meaningful representation on the hospital’s multidisciplinary STEMI committee. We’re not perfect, and we still have many, many opportunities for improvement, but it’s very important for EMS to have a seat at the table where the concerns of the various stakeholders can be discussed, and data can be shared between the hospital(s) and EMS. Every single case is a learning opportunity! I especially enjoy collecting the prehospital 12-lead ECGs of patients who were fast-tracked to the cardiac cath lab and had no clear culprit artery. It seems to me this is our best chance at reducing “false positives” while maintaining an acceptable degree of sensitivity.
I’ve given more thought to the idea of a 12-lead ECG certification for paramedics, and I do think the idea has merit, but it seems to me this should be the same type of certification a physician, advanced practice nurse, or PA would get. The “STEMI recognition” model will never be sufficient to eliminate the need for ECG transmission due to the problem of baseline abnormalities and STE-mimics, so any type of certification should be comprehensive and include rhythm analysis, axis determination, conduction abnormalities, STE-mimics, STEMI recognition (ischemia, injury, and infarct), as well as identifying acute STEMI in the presence of baseline abnormalities. It can be done, and it should be done, if we want to transition into the clinician model.
Having said that, ECG transmission does have some stand-alone merit and I don’t personally have a problem with the technician model if it leads to good outcomes for our STEMI patients. If you can get your EMS organization to identify the candidates for a prehospital 12-lead ECG, undress the patient from the waist-up, prep the skin and place the electrodes accurately, capture a 12-lead ECG with excellent data quality with the first set of vital signs and within 5-10 minutes of arriving on scene, and act on that ECG (whether it’s calling a STEMI Alert based on some set criteria transmitting the ECG for physician interpretation or both), and you do that well, to me that is a true mark of professionalism. We need to take pride in our workmanship whether we’re the ones who “make the call” based solely on our own interpretation or not.
The only thing I can think of that wasn’t touched on (much) in our discussion is the walk-in STEMI patient at the local non-PCI hospitals. I worry about the young, otherwise healthy patient who receives failed thrombolysis (TIMI 3 flow may be achieved only 50-60% of the time according to some studies) and languishes away in a hospital bed with a dying myocardium. Regionalized STEMI systems need to consider how walk-in STEMI patients are going to be treated within the context of the system. My personal feeling is that 100% of STEMI patients should be emergently transferred to a PCI-hospital, even if they receive first-dose thrombolytics at a non-PCI hospital (the Minnesota model).
A lot of rural EMS systems are loath to take their ambulances out of the county (or even out of service for 2-3 hours) for interfacility transports but this is a situation where they should make an exception when rotor-wing EMS or private ambulances are not available, and respond with all of the urgency of a 9-1-1 call (not necessarily “lights and sirens” en route to the hospital but respond right away).
If you need assistance or guidance as to how you should take the next step, I would encourage you to find out who oversees AHA Mission: Lifeline in your state, and get involved with your chapter’s EMS Advisory Committee. There’s no reason you need to “go it alone” because I can assure you, all of the EMS systems in your state are struggling with the exact same issues. The cross-pollination can be quite beneficial when EMS systems share solutions with each other, whether it’s with regard to education, technology, buy-in from the ED docs, turf wars between hospitals, obtaining funding for 12-lead ECG machines, developing protocols, obtaining representation on multidisciplinary STEMI committees, or comparing outcome data.
An 81 year male reports to the fire station to have his blood pressure checked.
He tells the paramedics he had just finished a round of golf and was sitting in the clubhouse when he felt, “cold and shaky.”
He relocated to his car with the windows rolled up and the A/C turned off. The ambient temperature was very warm but he still felt cold.
That’s when he decided to drive to the fire station.
At the time of evaluation his BP was 120/70 and his pulse was 76 and regular, which was consistent with the other vital signs recorded on his BP card over the past 2 weeks.
When he left the fire station he did not appear acutely ill.
Two hours later an ambulance was dispatched for a male patient with shortness of breath.
The paramedics recognized the man standing on the side of the road wearing a jogging suit as the same man who was at the fire station earlier for a BP check.
He states that he called his doctor who was out of town, and the on-call physician advised him to call 9-1-1.
The man was helped into the back of the ambulance and undressed from the waist-up. A surgical scar is noted down the center of his chest.
Past medical history: MI and CABG x3 in 1985
Meds: Unknown
His vital signs were assessed.
Resp: 18
Pulse: 80
BP: 114/76
SpO2: 96 on RA
He states that “nothing has really changed” since he was at the fire station.
When asked about shortness of breath, he denies it.
The cardiac monitor is attached.
When specifically asked about chest discomfort he states, “Well, I do a little bit of chest pressure, but it’s nothing like when I had my heart attack.”
A 12-lead ECG is captured.
What is your impression?
See also:
Our friends Thaddeus, Mark, and Justin from Chronicles of EMS, in part of their ongoing effort to find a suitable TV network, are changing the name of Chronicles of EMS.
It’s still going to be “Chronicles of EMS” but instead of “Chronicles of EMS – The Reality TV Series” it’s going to be “Chronicles of EMS – [Insert New Name Here]“. In other words, they need a new tag line.
That’s why they need your help! Here are the action steps you need to take.
1.) Join the Chronicles of EMS community.
2.) Submit your idea.
It’s that simple!
The winner will receive round trip tickets and 3 nights accommodation to a location of your choice (where the Chronicles of EMS will be filming) plus an iPad, and your name in the end credits of the show!
The “Name the Show” contest page is HERE. Full rules and regulations are HERE.
See also Medic 999′s blog post A Chance Of a Lifetime!
If you still don’t know what the Chronicles of EMS is you should watch the premier episode right now.
http://vimeo.com/moogaloop.swf?clip_id=9055077&server=vimeo.com&show_title=0&show_byline=0&show_portrait=0&color=&fullscreen=1
Chronicles of EMS – The Reality Series (Season 1 Episode 1) from Thaddeus Setla on Vimeo.
Thaddeus Setla, the co-creator of the show speaks directly to you on YouTube here.
You can help support Thaddeus’s audition for Oprah’s TV network by clicking HERE.
How would you describe this heart rhythm? Lead II is on top and lead V1 is on bottom.
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