Saturday, August 1, 2015

"Early Repolarization" followed by ventricular fibrillation.

This is a repost of part of one of the most viewed posts ever.

This patient with little past medical history presented feeling moderately ill.  He had an ECG recorded:   
QRS duration = 102 ms.  What do you think?


Due to the peaked T-waves, the residents were immediately concerned for hyperkalemia and sought an old ECG, which they immediately found in the medical record.  It was recorded with a K of 4.5 mEq/L: 
QRS 82 ms.  


The residents interpretation was that these were identical.  After viewing this previous ECG, and knowing that the K was 4.5 at the time it was recorded, the residents believed that the peaked T waves in ECG #1 were this patient's baseline.  

Are they identical?  

Inspect lead V4 more closely, here for a side by side comparison:
On the left, the ST segment is nearly flat and rises abruptly.  On the right, it is not flat (though nearly so) and rises slightly less abruptly




It is true that early repolarization has tall and relatively peaked T waves, but not to the extent seen in ECG #1. Without seeing them side by side, it is hard to appreciate the difference. 

This patient, then, did not get immediate treatment for hyperK. 

I saw these ECGs at a slightly later time than the resident, recognized the difference and, worried about the patient, started toward his bedside.  As I was approaching the patient, he had a v fib arrest.  He was immediately resuscitated, then his K returned at 7.0 mEq/L.   This was a presumed hyperkalemic arrest.  

Some say you don't need to treat hyperK unless there is QRS widening.  They claim that peaked T-waves are not enough.  This is only one case, and anecdotal, but we found no other etiology of arrest in this patient.  I always treat immediately if the ECG is affected by hyperK

There is a definite difference, with EKG 1 pathognomonic for hyperkalemia.

Tuesday, July 21, 2015

Emergency Transvenous Cardiac Pacing

This case was provided by one of our fine 5th year EM/IM residents, Rachael Krob MD. The description of the method for inserting a pacing wire is by one of our fine 3rd year EM residents, Mark Sandefur MD.

Case
An elderly male was found on the floor with altered mental status. When EMS arrived, he was obtunded but occasionally able to answer yes/no questions. He was found to be bradycardic in the 20's-30’s. Glucose was normal.  

A prehospital 12-lead was recorded; unfortunately, only half of it made it into the chart:
There is a slow indeterminate rhythm with a right bundle branch block morphology.  

The medics report that there was complete heart block. They gave atropine with no response, so they initiated transcutaneous pacing. They believed they had capture by palpating pulses and his mental status improved somewhat, so they had to give midazolam.  

On arrival in the ED, he continued to have altered mental status and shock, and so was intubated using RSI.

A cardiac ultrasound was performed during transcutaneous pacing.:
You can see the atrium beating at a normal rate, but the ventricle is responding very slowly.
There is normal-appearing myocardial contractility, but that the transcutaneous pacing was not capturing.  

Pacer pad placement was optimized with good anterior and posterior placement, and the amperage was turned all the way up, without capture. Because he was hypotensive and in shock, and he continued to have a heart rate in the 20-40’s, he was given 0.25 mg of push dose epinephrine, with improvement in blood pressure and heart rate. 

The decision was made to place a transcutaneous pacing wire. While this was being placed, transcutaneous pacing was discontinued due to the failure of capture and quick response to low dose IV epinephrine. A 12-lead ECG was obtained:
There is sinus tachycardia with complete (3rd degree) AV block and ventricular rate of about 50.  Notice the QRS morphology is that of RBBB and Left Anterior Fascicular Block.  
This means that the source of the escape is in the posterior fascicle.  
This is merely an interesting, though not critical, observation!
This was interpreted as bradycardia with complete heart block. While the pacing wire was being inserted, the patient received push dose epinephrine every 3-5 minutes as his heart rate and blood pressure would drift down. During this period, continuous cardiac ultrasonography showed the pacing wire in the right atrium. There was some difficulty with advancing the wire through the tricuspid valve into the right ventricle, but eventually placement was successful and appropriate capture was achieved:
 You can see the wire in the RV (see still picture with arrow in explanation below)

He was then admitted to the MICU with plans to go to the cath lab for a screw-in pacer. Outcome was good.

Placement of an Emergency Transvenous Pacer.  Ultrasound is the preferred method.

Indications (1)

I. Used for unstable bradycardia when other measures fail:
--Medical treatment is inadequate (e.g.: atropine, treatment of hyperkalemia, reperfusion for ischemia, etc.)
--External (transcutaneous) pacing fails to achieve capture, even after optimal placement and high output, or when not tolerated by the patient
--Even if transcutaneous pacing succeeds, it is usually not a good solution for multiple hours and may not be persistently efficacious.
--Often utilized in the setting of high grade AV node block, Sick Sinus Syndrome, etc.

II. Also can be used for overdrive pacing for unstable tachydysrhythmias, especially Torsades de Pointes (polymorphic VT due to long QT).

Contraindications(1)

Prosthetic tricuspid valve
Severe hypothermia
--Predisposes to VF
--Bradycardia is physiologic!

Research

Studies generally show approx 70-80% success rate.2,3
Average time to successful placement was 18 minutes.2
--30% less than 5 minutes
A 1981 study4 comparing flow directed balloon tipped catheters to standard semirigid electrode catheters revealed several important differences:
--Improved time: 6 min w/ balloon vs. 13 min w/ standard
--Fewer complications with balloon tipped catheters
Most studies assessing emergency transvenous cardiac pacing were preformed before the use of ultrasound.


Techniques

There are a couple well-described methods for this procedure:
--Sensing method
--EKG monitoring method
The main benefit of these techniques was that a physician could determine when the catheter reached the heart during the procedure without needing radiographs.

We will not discuss these techniques.

Ultrasound Technique: This is the preferred method at Hennepin County Medical Center because it is technically simpler and there are fewer opportunities for error.  It utilizes another physician or sonographer for real time ultrasound guidance. 


Place a Sheath Introducer


Right internal jugular or left subclavian veins preferred.
A Touhy-Borst Adaptor tightens around the wire, preventing leakage of blood or entry of air.

Insert the Pacing Catheter:

Roughly measure distance that will be needed.
Place a Tuohy-Borst adaptor with Cathgard on the introducer.
Insert the temporary pacing catheter into the Cathgard/sheath.
--Curvature must be directed to the left so the catheter can enter the heart:


Insert with Ultrasound Guidance:

A second provider uses ultrasound to identify the catheter entering the RV.
--Subcostal view preferred

The heart is bradycardic



Now the pacer wire is in place (see still image with arrow below) and the heart is being paced and is beating much faster.

Here is a still of the second ultrasound image:
The arrow shows the pacer wire.



Pacing Module:

An assistant connects the pacing catheter to the pacing module/box.
--Use the V ports
--Ensure correct placement of positive and negative electrodes in the module
--When the catheter is seen in the heart, turn on the pacing module.
Hit the “Emergency, Async” button, which initiates predetermined automatic settings (may vary depending on equipment):
--Asynchronized
--Rate 80
--A output 20 milliAmps (mA) (not applicable for our purposes)
--V output 25 mA



Confirm capture: ultrasound, pulse check, EKG
Adjust the rate if needed.
Tighten the Tuohy-Borst adaptor to help prevent displacement and extend the sterile sleeve.

Final Details

Obtain a CXR to confirm placement.
The pacer wire is in the RV.  Difficult to see here.  The image below shows its exact placement.
Ideal placement is in the apex of the RV.  This is not ideal, but is working perfectly.


Further Management

Discuss need for more definitive treatment with cardiology (placement of a screw-in temporary catheter, permanent pacemaker, etc).  

Temporary Pacers should be immediately replaced by more permanent ones.  Without the fixation into the myocardium with a screw (as permanent ones have), the temporary pacers can come loose and this is very dangerous!

Admit the patient to the ICU with pads in place.

References
1. Roberts JR. Roberts and Hedges’ clinical procedures in emergency medicine, 6e. Philadelphis, PA: Saunders; 2014:278.
2. Rosenberg AS, Grossman JI, Escher DJW, et al.: Bedside transvenous cardiac pacing. Am Heart J. 1969;77:697.
3. Kimball JT, Killip T: A simple bedside method for transvenous intracardiac pacing. Am Heart J. 1965;70:35.
4. Lang R, David D, Herman HO, et al.: The use of the balloon-tipped floating catheter in temporary transvenous cardiac pacing. Pacing Clin Electrophysiol. 1981;4:491.

Sunday, July 19, 2015

Palpitations in a Young Healthy Male

A previously completely healthy young man presented to the ED after an episode of palpitations, dizziness and weakness while at work today.   He experience a sensation of anxiety and then had sudden onset tightness in his chest, palpitations, dizziness, and weakness.  He tried to rest, but his symptoms became worse and he started to sweat profusely.  He began to hyperventilate and describes carpal spasm.  By the time he arrived in the ED, symptoms were largely resolved.  The etiology seemed to be a panic attack, but he had never had one before.

An ECG was recorded:  

Besides the RSR' (right ventricular conduction delay), what do you see?












There is a long QT (computer measured at 488 ms is correct).  There is also a large U-wave fused to the T-wave in V3.  Hypokalemia was suspected.


K returned at 2.6 mEq/L.

His K was replenished and he was admitted for monitoring.

Here is the ECG the next AM with a K of 4.4 mEq/L: 
Normal QT and normal U-waves.  RSR' persists.
Aside: you might be worrying about type 2 Brugada.  It is not type 2 Brugada as the beta angle is too narrow.  See this post on Type 2 Brugada Syndrome.
Mg was 1.6 mEq/L.  Etiology of hypokalemia would be evaluated as an outpatient.  He was discharged.

Discussion

Whether the hypokalemia was the etiology of the symptoms, by causing an unrecorded cardiac dysrhythmia, is uncertain.  But severe hypokalemia (K less than 3.0 mEq/L), especially when manifesting on the ECG as ST depression, long QT, or prominent U-waves, is a known cause of cardiac dysrhythmias, including malignant ventricular dysrhythmia.

A low serum K is representative of a VERY low total body K.  It cannot be replaced with a single dose of K replacement, as that will immediately redistribute to the intracellular space and hypokalemia will quickly recur.  Therefore, severe HypoK requires inpatient replacement with cardiac monitoring.

This ECG shows one of the reasons why it is important to obtain an ECG for syncope or palpitations.


How can you detect severe hypokalemia on the ECG?

Here are several examples.    Here are several more interesting cases of hypokalemia.

There is little literature on recognition of hypoK on the ECG.  Obvious large U-waves are very specific with a high Positive Predictive Value, but that is not sensitive.  

Below is an abstract we wrote back in 2010 in which we identify 3 important variables for diagnosing HypoK.  Unfortunately, one is a subjective critierion.


Abstract 400 (ACEP Research Forum): Derivation of a Rule for Diagnosis of Hypokalemia on the Electrocardiogram     Get rights and content

Annals of Emergency Medicine, 2010-09-01, Volume 56, Issue 3, Pages S129-S130, Copyright © 2010 American College of Emergency Physicians

Study Objectives

There is little data on the electrocardiographic (ECG) diagnosis of hypokalemia (HypoK). We hypothesized the ECG to be an accurate predictor of significant HypoK (K ≤ 2.9 mEq/L) or normoK (K ≥ 3.5 mEq/L) (NormoK).

Methods

Retrospective study. We searched the electronic medical record for consecutive emergency department diagnoses of HypoK, then hand searched for those in which there was an ECG recorded before administration of potassium (K), and the K was ≤ 2.9 mEq/L. For controls, we searched for consecutive ECGs in patients with K ≥ 3.5 mEq/L. Abnormal QRS (bundle branch block or intraventricular conduction delay) or extreme tachycardia (HR > 130) were excluded, as were redundant patients. One expert reader (ExR) and two resident readers (RRs) who underwent a short tutorial interpreted the randomly sorted ECGs while blinded to the K level and the Bazett-corrected QT interval (QTc-B). ECGs were analyzed for computerized QTc-B, presence of U-waves [None (NUW), subtle (SUW), or prominent (PUW)], T-Wave flattening (TF), and ST segment depression (STD). Resident readers combined, and the expert reader, noted subjective interpretations (SI, either ExR-SI or RR-SI) [definite HypoK (SI+), or not]. Analysis was by descriptive statistics, by Student's t-test and by Chi-square (CS).

Results

There were 100 cases of HypoK with an ECG; 13 were excluded, leaving 87. There were 58 controls. QTc-B was the single best differentiator, with accuracy (Acc) of 74%. Expert reader Acc was 72%, and Resident reader was 63% (p=.10 by CS). Mean QTc-B for HypoK was 475 ± 8.2 milliseconds (ms); for NormoK is was 429 ± 5.5 ms (p<0 .0001="" 100="" 3="" 78="" 79="" 80="" 83="" 86="" 89="" 92="" 98="" a="" acc.="" acc="" added="" and="" best="" by="" combination="" criteria="" diagnosis="" exr="" font="" had="" if="" none="" objective="" of="" or="" prolonged="" prominent="" qtc-b="" results="" rrs="" s="" sens="" spec="" student="" subjective="" t-test="" the="" these="" to="" two="" u-wave="" versus="" was="" were="" with="">

Conclusion

QTc is longer in HypoK than NormoK. Significant HypoK in the ED can be recognized on the ECG with high accuracy using QTc-B and presence of prominent U-waves. HypoK can be recognized with very high Sens, Spec, and Acc, using subjective interpretation of either the expert reader or the residents, plus QTc-B and presence or absence of prominent U-waves.

Thursday, July 16, 2015

Terminal QRS Distortion: Diagnostic of LAD Occlusion. Or is it Pericarditis?

A middle-aged woman presented with what is described as a burning feeling in her chest which the physician said was "very atypical."  It did occur during exercise and radiated to both wrists.

Here is the first ECG:
Sinus rhythm.  
Computerized QTc is 437.  
There is some ST Elevation in II and aVF but without reciprocal ST depression in aVL.  
Precordial leads also have ST Elevation:  Is this normal variant or is it Ischemic ST Elevation?  There is upward concavity in all leads, suggesting normality. But upward concavity is seen in all of leads V2-V6 in almost 50% of LAD occlusion.  There is no ST depression, Q-waves, or T-wave inversion.
The first impression of the clinicians was "pericarditis" because of the diffuse ST elevation.

The computer algorithm might say: "Diffuse ST elevation, consider pericarditis, early repolarization, or myocardial infarction." I don't know what it actually said.

Early repol vs. LAD occlusion

Should we use the LAD-Early Repol calculator?
If you did, and it was negative, it would likely be a false negative.  Why?
There is Terminal QRS distortion in V3, which is not a finding of normal variant ST elevation.
What is Terminal QRS distortion?
Terminal QRS distortion is the absence of both an S-wave or a J-wave in either V2 or V3.  It is not seen in early repolarization, or is very rare.  In the right clinical context, and in the presence of non-diagnostic ST elevation, it is highly suspicious for coronary occlusion.

They did apply the formula, using these measurements: 1.5 mm for STE at 60 ms after the J-point in lead V3, QTc of 437, and R-wave amplitude in V4 of 13.  (I would have used 2, 437, 14)

Their numbers resulted in 23.34 (very close to 23.4, but technically negative.  I recommend that anything above 22.0 be investigated further)

My measurements would have resulted in 23.6, also very close but positive.

Pericarditis vs. LAD occlusion

I always say "You diagnose pericarditis at your (and your patient's) peril." 

Why is this not pericarditis:
1. ST vector: The ST vector in pericarditis should be lateral and inferior and only slightly anterior.  The vector here is towards V3.
2. Large T-waves: in pericarditis, the ST elevation is much more pronounced than the T-wave.  Here the T-wave is more pronounced, hyperactute.
3. No diagnostic PR depression.
4. Notice there is a Spodick's sign in V3-V5. But this is a worthless sign (see this recent post).

They recorded 2 more ECGs at unknown intervals:

2nd:
Perhaps some increase in STE



3rd:
There is slightly increasing ST Elevation



















Fortunately, the troponin came back slightly elevated, and fortunately they did not not attribute that elevation to myocarditis.

The patient was taken to angiography and found to have a 99% thrombotic LAD occlusion.




Tuesday, July 14, 2015

A 30 year old African American with Chest pain and T-wave Inversion

A 30 yo African American Male presented agitated and with active chest pain, thought to be on a stimulant.  This ECG was recorded:
There is T-wave inversion in II, III, aVF and V4-V6.  What is it?


The patient was sedated and this was recorded 2.75 hours later:
Now there is sinus bradycardia.  The T-wave inversion is now seen in V2 and V3 in addition to V4-V6.  Inferior T-waves are no longer inverted.
Does this change your mind about the first? 





I was shown these ECGs without that information and asked if the patient was African American.  That is because they are classic "Benign T-wave Inversion (BTWI)."

What is particularly interesting here is the 2nd one: there is an apparently long QT interval, large U-waves in V2 and V3, and the development of T-wave inversion in V2 and V3 when it was not there on the previous.

The worry here was that it was Wellens' syndrome.  BTWI has a comparatively short QT.  My hand-measured, Bazett-corrected QTc in both of them is 415 ms.  The apparent increase on the 2nd is because the raw QT is longer, but is limited by the correction.  Wellens' is generally (but not always!) longer.

The giveaways are the tall R-waves in the affected leads, with minimal S-waves, and the presence of J-waves, especially in V3-V6 on the second ECG.  U-waves are a common feature of early repolarization, which is closely related to BTWI.

The really worrisome part is the change.  All I can say is that even normal "baseline" ECGs change from situation to situation.  Early repol is not stable over time.

The patient did indeed rule out for MI.

Here is much more on BTWI.

See especially this post.

Monday, July 13, 2015

Diffuse ST Elevation. Diagnosis confirmed with Bedside Echo.

A male in 40's with left sided chest pain since last night with associated shortness of breath. The pain worsens with turning on left side and is best when sitting forward.   He has some cough with sputum.  There was no pericardial friction rub.

Here is the initial ECG:
Diffuse ST elevation, without reciprocal ST depression, mostly in inferior limb leads and lateral precordial leads. This is very typical for pericarditis.

Some ECG factors to consider in diagnosing pericarditis:

1. Diffuse STE, fulfills
2. STE vector towards leads II and V5, fulfills
3. Absence of reciprocal ST depression, fulfills
4. Presence of PR segment depression, fulfills
                 [but is not diagnostic (only about 0.5 mm, which can be normal)]
5. T-waves not prominent, especially ST/T ratio in V6 greater than 0.25, fulfills
6. ST depression in aVR and V1, fulfills
7. Spodick's sign: downsloping TP segment.  This is now known to be neither sensitive nor specific for pericarditis (personal communication on research done by Amal Mattu).  It is absent here.

All these signs are discussed in this recent post.

Clinical factors:

1. Definitely positional
2. Friction rub, not present
3. Pericardial effusion (good specificity, poor sensitivity)

Case progression: 

A bedside echo was done:



Notice the small effusion, seen close to the transducer as a 5 mm echo free stripe.  Furthermore, there was no wall motion abnormality.

Effusion very much increases the probability of pericarditis (though beware hemopericardium in cases of MI with rupture or aortic dissection).

The chest X-ray was negative.

The patient was admitted and ruled out for MI.

Another ECG was recorded 24 hours later:
T-waves are slightly more prominent in affected leads


This is then a classic presentation for pericarditis.  He was treated with NSAIDs and Colchicine.







Friday, July 10, 2015

Lateral Hyperacute T-waves in V5 and V6

A middle aged male with no significant past medical history complained of several hours of chest pain.

Here is his initial ED ECG:
The computer read: left anterior fascicular block and old anterior MI.  No other comment.
What do you think?


--There is a large pathologic QR-wave in I and aVL, and small ones in V3-V6.  (Leads V2 and V3 must be reversed, as the QR progression is interrupted and only makes sense if one interprets them as switched).  These are diagnostic of MI of unknown age.
--The STE in aVL, with minimal reciprocal ST depression in inferior leads, in the setting of well-formed Q-waves, is also of unknown age, but very likely to represent old lateral MI with persistent ST elevation.
--There is less than 1 mm of STE in I, aVL, V5 and V6, but these leads are notoriously insensitive for coronary occlusion.  Only about 50% of occlusion of arteries supplying this area of myocardium have ST elevation that meets "criteria" of 1mm or more.
--However, the T-waves in V5 and V6 make this diagnostic of coronary occlusion.  They are far too tall and fat to be normal.  They are hyperacute.

An ED bedside ultrasound confirmed anterior wall motion abnormality.

The cath lab was activated.  At cath, a nearly occluded (TIMI-1 flow) first diagonal was found and stented.  Peak troponin I was 41.84 ng/mL.

Echo showed mid-anterior and anterolateral akinesis, with an EF of 58%.

Here was the post PCI ECG:
Now the T-waves are much more normal.  Q-waves are more well developed in V5 and V6.  The STE in aVL is still present and may well have been due to old MI (which is also, again, strongly suggested by the well-formed, deep and wide Q-waves).


Hyperacute T-waves in V5 and V6 are occasionally the only indication of coronary occlusion.

See V5 and V6 in this case, which is even more interesting. 

Also this case


Wednesday, July 8, 2015

Long QT Syndrome with Continuously Recurrent Polymorphic VT: Management

A young woman presented with intermittent shocks from her implantable defibrillator.  She was intermittently unconscious and unable to give history.   The monitor showed intermittent polymorphic ventricular tachycardia.    The physician was presented with this ECG at the same moment he was observing the repeated syncope:

Time zero
It is a bigeminal rhythm with a very bizarre PVC.  The PVC has an incredibly long QT, but the intervening native rhythms do not.  However, when I saw this (it was texted to me), it immediately reminded me of this case, so I knew by sheer recognition that it was long QT and the patient was having Torsades de Pointes.  

The patient was moved to the critical care area.  An ICD was noted on her chest.  Vital signs were normal when the rhythm was normal. 

Another ECG was recorded 8 minutes later:
The computer measures the QT as 435 ms and QTc as 435 ms.  What do you think? 






As I have pointed out many times, the computer is awful at making the diagnosis of long QT.
See these posts:
Do not trust the computerized QT when the QT is long
Altered Mental Status, possible ingestion.  What does the ECG show?


The QT is at least 640 ms, and QTc(Bazett) also = 640 ms (RR interval = 1)


The monitor showed continued bursts of tachycardia, and another 12-lead was recorded, this one at 15 minutes:
Polymorphic VT initiated by R on T


At 22 minutes, 4 continuous ECGs were recorded:

More R on T initiating Torsade

Same. Notice that you can see the R-R interval that precedes the complex that precedes the R on T in 2 places.  In both, the R-R interval is greater than 1 second.

Same



As the patient was repeatedly losing consciousness and not protecting her airway, she was intubated and started on propofol.  She was given 3 grams of magnesium.  Her rhythm stabilized and this ECG was recorded:
Sinus Tach and long QT, but no more Torsades.

And another:
Sinus Tach and Even longer QT; still, no more Torsades

Her heart rate slowed:
Now there is atrial pacing at a rate of 60 and still a very long QT.


Further history revealed a previous history of long QT, presumed congenital, with history of syncope and cardiac arrest.   The patient had also been on Nadolol.  The K returned at 3.3 mEq/L and Mg at 1.7 mEq/L.  IV potassium was given.

The patient remained stable after these interventions.


It was later found that she had not been taking her Nadolol (a non-selective beta blocker).


She was restarted on Nadolol and her pacer rate was increased to 80, making the longest possible R-R interval 750 ms.  When the rate is increased, the R-R intervals are decreased, and thus the preceding R-R interval is decreased.  This shortens the QT, and diminishes the probability of getting an R on T.



But wouldn't beta blockers (BBs) decrease the heart rate and thus increase the R-R interval and therefore lead to lengthened QT and increased risk?  NoBBs work by mitigating the adverse effects of sympathetic stimulation on the membrane ion channel.  Sympathetic stimulation directly affects the QT interval, although this is mainly in LQT1 and LQT2.  LQT3 is different.  Here is a thorough article from UpToDate on the topic, if you have access.

Why did the Torsades stop with intubation and propofol?


This is congenital long QT: Most of these (LQT1 and LQT2, but not LQT3) are made worse by catecholamines, and are treated with beta blockers (As is Catecholaminergic Polymorphic Ventricular Tachycardia, but for different reasons).  By taking away the endogenous catecholamines, intubation and sedation may have been all that was necessary.  Administering Mg and K contributed as well.  This episode was probably initiated by both Nadolol noncompliance and hypokalemia.  


What do beta blockers (BBs) do?  See this article.  It is very confusing because their effect is different for the different types of Long QT, with some at least apparently conflicting evidence (conflicting to me anyway, and I am no expert!).  LQT1 and 2 behave similarly, but LQT3 appears to be opposite (apparently similar to acquired long QT).  For LQT1 and 2, epinephrine infusion lengthens the QT and increases QT dispersion (differing QT intervals throughout the myocardium, which also increases vulnerability to Torsade); conversely, BBs both shorten the QT interval and decrease dispersion, mitigating the risk of Torsade.  Exception: However, in LQT3, beta stimulation does the opposite, and beta blockers may facilitate Torsades.


The data is conflicting, however: whereas, in accordance with the above, observational studies show that BB are most effective in LQT1 and also in LQT2, observational studies of patients with LQT3, which it seems should be opposite LQT1 and 2, have been variable; they do not necessarily show an adverse effect of BBs.  See this article.  And this article.


BBs also decrease the triggering PVCs ("early afterdepolarizations"), mitigating the risk of Torsade. 

Here is another point of confusion: The patient's heart rate was increased with pacing, but held in check with Nadolol.  In fact, this seems to be ideal, as pacing decreases the risk of Torsades if the heart is protected from sympathetic stimulation: see this study.  Although the primary effect of beta blockade is on the ion channels themselves, UpToDate states that: "The goal of beta blocker therapy is to blunt the maximal heart rate achieved during exertion, and is particularly important in patients with LQT1 who are at increased risk during exercise. A theoretical concern is that beta blockers also decrease the sinus rate, a property that may prolong repolarization and potentially predispose to TdP."

Acute management of Torsades specifically due to congenital long QT: I have been unable to find any guidelines or articles specific to the emergency treatment of recurrent Torsades due to congenital long QT (in contrast to acquired long QT) except for the following statement in UpToDate: "In those with congenital long QT syndrome, beta blockers may be used to reduce the frequency of premature ventricular contractions and shorten QT interval."  There is no recommendation as to which beta blocker should be used in this acute situation.  In chronic therapy, Propranolol and Nadolol are best, and metoprolol appears to be ineffective.  Both propranolol and nadolol are nonselective (both Beta-1 and Beta-2) blockers.   Is the absence of selectivity critical to the treatment?  I do not know and could not find out.  Nonselective beta blockade has its adverse effects, including bronchospasm.  Furthermore, my favorite beta blocker in the ED is esmolol because it can be immediately turned off (very short half-life).  However, it is beta-1 selective and I don't know if it would work.


Here is a great review of the chronic management of long QT syndrome.


Management of Polymorphic VT (PMVT)

Non-Torsades Etiologies of PMVT (normal QT)
Most commonly due to ischemia.  These will almost always be overt, severe episodes of ischemia, with chest pain and/or unequivocal ischemic ECG abnormalities. Also due to pre-existing cardiomyopathy.

Management of polymorphic VT (with long QT = Torsades de Pointes)
Most torsade is self-limited.  If it does not spontaneously convert, then it needs defibrillation if the patient is unstable.  If it does convert, then it is likely to recur, and therapy is aimed at preventing recurrence.

Therapy of Acute Episodes of Torsades:
1. Cardioversion or Defibrillation if active, especially if unstable
2. Removal of offending agent in acquired long QT (usually a medication)
3. Correction of hypoK, even to slightly supranormal levels. K helps to prevent the early afterdepolarizations (PVCs) that initiate Torsades with R on T.
4. Administration of 2-4g of MgSO4 even if the Mg level is normal (a drip of 3-10 mg per minute may be useful).  Mg also helps to prevent the early afterdepolarizations (PVCs) that initiate Torsade with R on T.
5. Only if it is acquired long QT: beta-adrenergic stimulation with isoproterenol
6. If these do not work, then overdrive pacing, usually at a rate of about 100 to prevent any pauses, will almost always work (transcutaneous pacing is fine for temporary relief as a bridge to transvenous pacing).
7.  Lidocaine may also be of benefit because it can suppress the PVCs (early afterdepolarizations) which initiate Torsades if they occur on the T-wave. 
8. Amiodarone is of questionable benefit, and possible harm.  By itself, it lengthens the QT interval, though without greatly increasing the risk of Torsades 
9. Do not give beta blockers unless the patient carries a diagnosis of congenital long QT.  Just the opposite: isoproterenol.

10. If it is congenital [congenital long QT, or catecholaminergic PMVT (which has a normal QT interval)], then acute beta blockade may be indicated.  I would try esmolol first, as it can be turned off.  However, it does not have beta-2 blockade and it is unclear to me if this is important and/or necessary.  If esmolol does not work, then IV propranolol should be given.



At the bottom are more specific guidelines for catecholaminergic PMVT.

Therapy of Acute Non-Torsade PMVT: Similar to Monomorphic VT (except for catecholaminergic PMVT, which is outlined below)
1. Cardioversion or Defibrillation if active
2. Correction of electrolyte disorders, especially hypoK or hypoMg
3. Prevention of further episodes with lidocaine or amiodarone, possibly a beta blocker such as esmolol (which you would avoid in any acquired long QT Torsades).
4. Anti-ischemic therapies, up to and including revascularization
5. Implantable Cardioverter-defibrillator may be necessary even with successful revascularization


Catecholaminergic PMVT:

1. Cardioversion or defibrillation (depending on presence of pulses), but with beta blocker pre-treatment (if possible), as the shock itself can cause catecholamine surge, further aggravating the situation and causing early recurrence of VT.

2. Intravenous beta blockers should be administered.  Esmolol is a great choice, as it has a very short half-life and can be turned off if there are complications.  Dose: Esmolol can be given in a bolus of 500 mcg/kg (0.50 mg/kg), followed by a drip of 50 mcg/kg/min (0.05 mg/kg/min).  It can be rebolused repeatedly, as needed, each time increasing the infusion by 50 mcg/kg/min.

3. For recurrent VT in the absence of prolonged QT, amiodarone should be administered by bolus and drip.  Amiodarone has beta-blocking effects.

4. Verapamil is recommended based on studies in which it prevents exercise-induced PMVT (3, 4).  However, I haven't found literature on its use in the acute situation.  Our electrophysiologist wrote that he would try it.  In this case, it appears to have made things worse, but that is the problem with isolated cases without control groups.

4.  Sedation, as in this case, to decrease sympathetic drive?  Or, class IIb in ACC/AHA guidelines for incessant VT is general anesthesia.

Avoid isoproterenol and overdrive pacing.  For polymorphic VT due to acquired long QT (Torsade de Pointe), isoproterenol is indicated to increase the sinus rate and prevent further torsade.  However, this makes CPVT worse.  Fortunately, Torsade is more common, but if you know the patient has CPVT, avoid isoproterenol.

Overdrive Pacing is listed as class IIb for incessant VT in the ACC/AHA guidelines, but this should not to be applied to CPVT.  

Overdrive pacing is used to prevent recurrence of pause-dependent PMVT (Torsade), which is worsened by bradycardia and improved by tachycardia).  The pathophysiology of CPVT is very different from Long QT syndrome.  CPVT, unlike Torsade, is worsened with tachycardia.   See this post for management of Torsade.