We discuss the ReadyLink 12-Lead ECG by Physio-Control , the RescueNet 12-Lead by ZOLL Medical Corp., 12-lead ECG interpretation, regional STEMI care, and ECG transmission in general.
This ECG shows a regular narrow complex tachycardia at a rate of 170.
Could it be sinus tachycardia? One of the "rules of thumb" for the maximum sinus rate is 220 minus age. This patient is 83 years old. 220 – 83 = 137. Granted, this is just a rule of thumb so I'm sure expections exist but 170 is a good distance from 137.
I agree with some commenters that atrial fibrillation can appear regular at very fast heart rates. However, a trained eye can still pick up on some irregularity with rates < 200. You can also use calipers or fold the ECG paper in half and line up the R-waves to verify that the rhythm is regular.
In this case the rhythm is clearly regular which rules out atrial fibrillation but not 2:1 atrial flutter.
In lead V1 we can see atrial complexes (inverted or "retrograde" P-waves) after the QRS complex. We're narrowing in on the mechanism of this tachycardia. If we play the odds there's a good chance this is AV nodal reentrant tachycardia (AVNRT). However, it could still be 2:1 atrial flutter or the less common (but not uncommon) orthodromic AVRT.
You will recall that the paramedics documented "cannon waves" that corresponded to the heart rhythm. Some of you asked, "What are cannon waves?" Cannon waves are pulsations that are visible in the external jugular veins when the right atrium contracts against a closed AV valve.
Normally atrial systole is an end-diastolic event (the so-called "atrial kick"). When the P-waves follow the QRS complexes the pressure generated by ventricular systole have already forced the AV valves shut. Hence, the atria contract against closed AV valves and back pressure creates a visible "wave" or pulsation that is transmitted back up the superior vena-cava and to the external jugular veins.
Here's an example to give you an idea although this patient's external jugular veins are severely distended and the heart rate is much slower. For the current case study the patient's cannon waves were fast, regular and visible just above the clavicle on the right side.
Does determining the exact mechanism of the tachycardia matter in the field? No, because that's not possible. We don't have an EP lab. However, we can carefully document the arrhythmia before and after treatment on those occasions where the patient is not critically unstable!
The first thing the treating paramedics did was put this patient in a supine position and place him on oxygen which perked him up a little bit. Remember, BLS before ALS. I am aware of the controversy associated with placing a patient in Trendelenberg. However, I think we can all agree that lying flat is better than sitting or standing when you're hypotensive!
Vagal maneuvers were attempted (the patient was asked to "bear down" and blow into an empty syringe) with no effect to the tachycardia. An IV was started but unfortunately the only good peripheral access was a 20 G IV in the back of the left hand.
Many (perhaps most) lf you recommended synchronized cardioversion for this patient. I have no quarrel with that. However, I do know that it's easier to say than do when you have a conscious, talking patient in the back of the ambulance. It also helps if you carry the right drugs and don't have to play "mother may I" with online medical control.
In this case paramedics pushed the PRINT button and gave 6 mg of adenosine followed by a 5 ml "flush" of 0.9% NS. It took more than 30 seconds to have an effect (Clinical tip: always follow adenosine with a minimum of a 20 ml flush) but here's what happened. The next four strips are continuous.
With the conversion to sinus rhythm the patient felt much better.
Vital signs were re-assessed.
RR: 18
Pulse: 100
NIBP: 138/81
SpO2: 100
A post-conversion 12-lead ECG was captured.
The patient was transported to the hospital in a position of comfort.
EMS World Magazine has named the ReadyLink 12-Lead ECG by Physio-Control as one of the Top Innovations of the Year. The award was presented at the New York State EMS Symposium – Vital Signs 2011, in Syracuse, NY.
ReadyLink enables basic life support EMS teams to acquire and transmit a patient’s 12-lead ECG to hospitals using Physio-Control’s LIFENET System, a cloud-based data management network for remote physician interpretation and decision support, providing clinicians earlier insight into a chest pain patient’s condition, especially in rural areas with limited access to advanced life support providers.
Physio-Control's Frank Piraino at Vital Signs 2011
EMS is dispatched to a "cardiac patient in distress".
On arrival paramedics are led to the bathroom where the patient is found sitting on a foot stool. He is conscious but appears acutely ill. Skin is pale and he is slumped over. He states that he feels weak.
Past medical history: High blood pressure, high cholesterol, valve surgery.
Medications: Numerous but his spouse can't locate them. When the patient is asked for his medication list he states, "Ask my wife."
Vital signs:
RR: 18
Pulse: Rapid and weak
NIBP: 85/53
SpO2: 99 on RA
Breath sounds: Clear bilaterally.
Cannon waves are noted at the patient's neck.
The cardiac monitor is attached.
A 12-lead ECG is captured (retrieved here from the LIFENET).
To recap, our patient overdosed on an unknown quantity of unknown medications. She is hypotensive and firefighters are maintaining her airway with an OPA and assisting ventilations with a BVM. She has a history of suicide attempts and was found down in her grandmother's home, who recently passed away.
Before we cover our patient's rhythm, it is important that we ensure our patient's ABC's are being appropriately managed. In this case, given the patient is deeply unresponsive we should consider placement of an advanced airway. If transport time is short, consideration should be given to continuing BLS airway maintenance.
She is also hypotensive, so while our patient is being preoxygenated–which is not the same as hyperventilated–we can work to establish IV or IO access. Our crew in this case used this approach, establishing a large bore IV while the firefighters ventilated the patient. Shortly after access was acquired, her SaO2 had risen to 98% and she was intubated without diffuculty.
With her ABC's covered, we can take a look at her initial rhythm:
At a first look, the complexes are wide and this could be a fast irregular rhythm or even a bigeminal rhythm. Closer inspection reveals regular P-waves with a slightly prolonged PRi and a 1:1 association with the QRS complexes.
The QRS complexes are wide and we may have wide premature complexes following them. However, these apparent PVC's fall during the absolute refractory period and therefore must be T-waves. Hyperkalemia is a strong possibility. This is a normal sinus rhythm with a 1st Degree AV Block, a wide QRS, and a prolonged QTc.
If the rhythm strip did not have you taking a second look at the T-waves, the 12-Lead ECG certainly did. They tower over the QRS complexes and a symmetrical and peaked. A left bundle branch block is present and the axis is normal.
At this point we need to strongly consider what medications our patient may have ingested. Most field providers should be knowledgable with the common medications geriatric patients are prescribed, especially those being treated for depression. We should be concerned for an acute overdose of one or more of the following:
Narcotics
Tricyclic antidepressants
Antiarrhythmics (including beta and calcium channel blockers)
Diuretics
Oral hypoglycemics
As many readers pointed out, this case is likely a tricyclic overdose, but it does not have all of the classic ECG signs. Present are many of the sodium channel blocking effects, including a prolonged PRi, widened QRS, and prolonged QTc. However, missing are the rightward terminal axis and the anticholenergic-like tachycardia. Because of this combination, often times the presenting rhythm is a bizarre wide complex tachycardia.
The rightward terminal axis in a TCA overdose manifests itself as slurred S-waves in multiple leads and a characteristic large R wave in aVR as seen in the figure below:
The crew in this case elected to treat for suspected tricyclic and potentially a concurrent narcotic overdose. They administered 2 L of normal saline, 1 mg naloxone, and 100 mEq of sodium bicarbonate. An OG tube was placed but not used. At the ED, a tox screen was positive for tricyclic antidepressants and barbiturates. Lab values were not available to the crew.
Polypharmacy overdose presents a challenge to both pre-hospital and hospital providers. Rapid intervention in the face of incomplete information is often necessary and the ECG can provide key information to guide treatments.
The ECG can neither unequivocally rule in nor rule out impending toxicity; recognizing these limitations, the emergency [providers] can use this bedside tool in combination with other clinical data during the assessment of the poisoned patient. -Harrigan and Brady
In this episode Tom Bouthillet, David Baumrind and Christopher Watford and joined by Monica Kleinman, M.D. the Chair of the AHA's Emergency Cardiovascular Care Committee.
Monica Kleinman, M.D.
Chair of the AHA's Emergency Cardiovascular Care Committee Photo credit: www.childrenshospital.org
Thanks go to an anonymous reader for this excellent case, as always we hope you find it as interesting as we did! As always, details have been changed where appropriate to protect patients and providers.
You're on an ALS fly-car dispatched for an unresponsive female, a BLS ambulance and engine company are already en-route.
You arrive to a small townhome in a quiet retirement community, finding the engine and BLS unit on scene already; a firefighter is in the doorway waving you inside. He grabs your monitor and directs you to a back bedroom.
The crew has already moved the patient to the floor, placed an OPA, and is assisting ventilations. A panicked young man is pacing on the other side of the bed. One of the firefighters places your patient on the monitor. You introduce yourself to the young man–her boyfriend–and get a quick history.
"She's not been herself today, depressed and crying. This is her grandmother's house, she died two days ago."
When asked about medication usage, medical problems, or other pertinent history he says he's not sure, but that she's tried to commit suicide in the past.
One of the BLS providers gives you the initial vitals:
GCS: E1V1M4, "no problems with the OPA"
Pulse: 75 bpm, no radials, weak carotids; "but the monitor says 140 bpm"
BP: 62/38
RR: 6, now assisted at 12
SaO2: 70% prior to ventilations, 77% @ 15 L/min
BGL: 192 mg/dL (10.6 mmol/L)
The initial rhythm strip is torn off and handed to you as they package the patient for transport.
A quick physical exam reveals no trauma, clear and equal lung sounds, 5mm equal and reactive pupils. A quick scan of the room finds no medicine bottles, but the boyfriend remembers her grandmother taking medication for depression.
In the back of the unit the BLS crew obtains a 12-Lead at your request while you start an IV.
The interpretive statement reads Atrial Fibrillation with Rapid Ventricular Response and Left Bundle Branch Block. It is a 20 minute ride to the nearest hospital.
What does the rhythm strip show?
What does the 12-Lead ECG show?
What is your working diagnosis and treatment plan for this patient?
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