Cam Pollock and John Friederich from Physio-Control put on a demonstration for us at Fire-Rescue Med 2012 to show how the LUCAS Chest Compression System can be incorporated into a "pic crew" concept for CPR and resuscitation. As you will see the application of the LUCAS device need not cause a significant delay in chest comrpessions.

Sometimes, troubleshooting an ECG is more than just lead placement. In this case report, we had three 12-Lead ECG's, all featuring a similar pattern: inappropriate R-wave progression.

Initially, when reviewing the first of these ECG's, I had believed it to be lead placement error. The most likely cause of inappropriate R-wave progression and low voltage in a precordial lead is the placement of the electrode on the mammary tissue or on the abdomen.

After reviewing two more ECG's from two different shifts, it became evident that the problem was more likely with the equipment than operator.

Two of the paramedics on duty were alerted to the possibility of a malfunctioning cardiac monitor, and the same was taken out of service for testing. During their investigation, it was found that the cables themselves were at fault.

The following is a 12-lead ECG acquired from one of the Paramedics using the current set of malfunctioning LP15 cables:

A set of LP12 cables was then connected to the same Paramedic and then connected to the same cardiac monitor:

The difference in these 12-Lead ECG's is striking.

Remember, R-waves should progress in a continuous fashion from V1 through V6. Usually with a transition from negative to positive around leads V3 and V4. This is known as good R-wave progression.

With Paced Rhythms, RBBB, LBBB, RVH, LVH, or myocardial infarctions this zone of transition and R-wave progression may be early or delayed. You'll often hear about poor R-wave progression or an early or late transition. These refer to the change in dominant polarity across the precordial leads, whether from positive to negative or vice versa.

In any case, the changes must be continuous. Any discontinuity indicates a problem in acquisition.

Whenever you review a 12-Lead, be sure to consider the validity of the tracing beyond simple interpretation. You should be checking for baseline wander, excessive artifact, and electrode placement.

• What types of machine failures have you seen that have gone unnoticed?
• Do you have a QA program in place to assess the quality and accuracy of 12-Lead ECG acquisition?
• Does your department discuss data quality issues during training?

See also:

Precordial Leads – The Transition, R-Wave Progression, R/S Ratio in Lead V1

The first 12-Lead ECG is from an 88 year old male with chest pain:

The second 12-Lead ECG is from a 40 year old female with chest pain:

The third 12-Lead ECG is from a 58 year old male with dyspnea:

• What is it about these three 12-Lead ECG's that is so striking?
• What are your differential diagnoses for these three patients?
• Are these three patients experiencing the same pathophysiology?
• What are the potential causes of the patterns found on these three separate ECG's?

While he is alert and oriented, he is also anxious and diaphoretic. Lungs are clear bilaterally, but the RR is elevated at about 30. Pulse is too fast to count, but the BP is 126/70. He describes the chest discomfort this way: "I feel like someone is punching me in the chest!" It is substernal, non-radiating, and rated a 5/10. His only other complaint is a touch of lightheadedness.

Here is the rhythm strip and 12 lead:

Your mission, should you choose to accept it, involves coming up with a differential diagnosis for our patient, and stating which factors favor one diagnosis over another. Oh, just one more thing… How do we treat him?

We look forward to your excellent responses!

It's important to collect data so we can measure our progress and prove that we are saving lives, but as we build these systems of care we must always remember that these are our mothers, fathers, sisters, brothers, sons and daughters.

Click HERE

Excellent job by AMR and Portland Fire Department! 

For starters, i think we all agree that the patient, with his signs and symptoms, needs to be transported. We have all had patients like this who don't want to go, even though we know they should. Patients say they don't want to go for different reasons… some want to use us as a "litmus test", gauging their need to go by our reaction. Others don't want to put us through the trouble. Some are afraid of not coming home, and some, just plain don't want to go. We have to do everything possible to convince them to go, and as we know, sometimes that requires quite a bit of persistence!

Now, about that 12 lead:

There is sinus rhythm, with a rate of about 80 and a normal PRI. The QRS is wide (124ms). There is Right Bundle Branch Block, with an rsR' in V1, and s waves in I and V6. 

Do we see any other abnormalities on the 12 lead? RBBB should have T waves appropriately discordant to the terminal portion of the QRS. There should be no ST elevation in the right precordials…  in fact, you might expect a slight bit of ST depression in V1 and V2 opposite the QRS. For the most part though, the ST segments are not deviated as they are in LBBB, which makes it possible to assess ST segments normally. Let's take a look in V1 and V2:

There is a slight amount of ST elevation in V1. This is not normal. V2 has concordant T waves, without ST elevation, which is also concerning.

Is this an anterior STEMI? Not so fast… let's see what the rest of the 12 lead shows:

There is ST elevation in aVR (about 2mm)  and slight ST elevation in V1, with ST depression in leads I,II,III,aVF and V3-V6. This constellation of "global" ST depression with ST elevation in aVR and V1 is typical for subendocardial ischemia. Could it be posterior STEMI? Not likely in this case. The anterior ST depression of posterior STEMI is usually maximal in V2-V4, and that is not the case here. It looks different as well. It helps me to visualize the direction of the ST segments. Think about where the ST depression is: inferior and lateral. What would be reciprocal to inferior and lateral depression? Rightward and superior ST elevation, which is exactly what we see here. This is what it looks like on the hexaxial reference system:

We see the direction of ST depression (blue arrows) and the reciprocal ST elevation (red arrows).  You can't have a STEMI in aVR, so you can see this is just opposite the diffuse ST depression. In the precordial leads, the lateral ST depression is opposed by the slight ST elevation in V1. This would not be considered a  STEMI.

This pattern of diffuse subendocardial ischemia could be due to a left main lesion, proximal LAD lesion, or 3 vessel disease. We can not tell from the ECG. People rarely survive long with a left main occlusion, which makes that unlikely (unless there was much collateral circulation). The most common issue is left main ACS, which is not a STEMI equivalent.

In the field, we treat this patient for ACS with our standard meds… For some agencies that carry Clopidogrel, probably not a good med for this patient in case he needs CABG. At the hospital, he won't get thrombolytics because it is not STEMI. Most likely he will be medically managed, with PCI to follow if medical management doesn't work, or his symptoms worsen.

Unfortunately, we don't have an outcome for this patient, but he crew was able to convince him to be transported.

For more information on subendocardial ischemia, read this great post by Dr. Smith.

Click HERE

See also:

Episode 1: Rural STEMI sytem of care – Sioux Falls, SD

Episode 2: Understanding STEMI from the ground, up – RACE Program, NC

EMS is called to the residence of a 69 year old female who is complaining of sudden onset of shortness of breath and weakness.

• Past medical history: Healthy
• Medications: None

The patient is seen in the emergency department of a local community hospital where she is found to have slight J-point elevation in the anterior leads.

(The vital signs and results of the physical exam are not available.)

Approximately 2 hours later there is a slight change in ST-segment morphology and new T-wave inversion in lead aVL. A cardiologist is consulted via telemedicine at the tertiary care center and the decision is made to transfer the patient.

Concurrently with this decision the patient is given 3 doses of SL NTG with complete resolution of her symptoms.

The transport ambulance arrives and records the following 12-lead ECG.

Several more are recorded en route. Here's the ECG captured on arrival at the PCI-hospital.

Do you think this patient is having a STEMI? Why or why not?

Click HERE to check it out!

Kudos to the HeartRescue Project for developing this "Save a Life" Simulator!

This should go a long way toward preparing lay bystanders for the "shocking" reality of encountering a sudden cardiac arrest in the community. I think this is an excellent tool to leverage through social media so be sure to share with friends and family!

My only criticism is that there are no post-shock compressions.

EMS is called to the local Urgent Care for a 63 year old male complaining of upper jaw pain related to "dental work". He had made two trips to the dentist this past week for pain related to "work done on a crown". Both times the dental work was in order, and the dentist could not find a reason for the  jaw pain. Today, while walking on the treadmill at the local fitness center, the jaw pain returned. He drove to urgent care because the dental office was closed. 

While at urgent care, he reported to the nurse that the pain began about 45 minutes ago, and seemed to worsen when he did strenuous activity. He thought it odd that today he had some chest discomfort as well, but felt it was probably due to his anxiety.

EMS arrives to find the patient in exam room 2. He looks pale, and his skin is cool and moist. He reports jaw pain of 8/10, and substernal chest pain of 4/10. History is significant for hypertension and anxiety. He takes Lipitor, ASA, and Metoprolol daily. He has no known allergies. His vitals are as follows:

• HR: 90 and regular
• BP: 180/114
• RR: 16
• Skin: cool/moist/pale
• Lungs: clear bilaterally
• Spo2: 98% on supplemental oxygen

You apply your cardiac monitor and acquire the following rhythm strip and 12 lead ECG:

Prior to EMS arrival, the patient was given 4 baby aspirin, but now refuses nitro and the IV. He states he "doesn't know what all the fuss is about", and that he "just wants to go home", and you get the feeling that he just might refuse transport.

• What do you tell your patient?
• Are you concerned about the ECG? If so, why?
• How would you treat this patient, and where would you like to take him?