Exam 1 Basic EKG Flashcards by Propofol Papi

The heart has the innate ability to generate its own spontaneous action potentials without any external stimuli, a phenomenon known as __________.

Automaticity

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When there is a stimulation above the threshold, __________ channels cause cell-to-cell conduction resulting in depolarization.

This will release ________ to interior myocytes and causes contraction.

_______ outflow causes repolarization.

Sodium Channels

Calcium

Potassium

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Once the action potential is generated by the SA node, conduction will through the right atrium via the __________ pathway.

Conduction will also travel from the right atrium to the left atrium via ____________.

Internodal Pathway

Bachman’s Bundle

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The inherent pacing rate of the SA node, AV node, BOH, BB and Purkinje fibers? What is another word that could be interchangably used for “inherent pacing”?

SA: 60-100 bpm

AV and BOH: 40-60 bpm

BB and PF: 20-40 bpm

Automaticity

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Atrial fibrillation will result in a _______% decrease in cardiac output.

20-30% decrease in CO

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How many mV are the large boxes?
How many mV are the small boxes?

How many seconds are the small boxes?
How many seconds are the larges boxes?

0.5 mV
0.1 mV

0.04 seconds
0.20 seconds

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What does the P-wave represent?

What is the normal duration of P-waves?

What leads are P waves positive?

Atrial Depolarization

less than 0.12 seconds

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What does the PR interval represent?

What is a normal PR interval?

What is a PR interval greater than 0.20 seconds called?

PR interval represents the time from the onset of atrial depolarization (contraction) to the onset of ventricular depolarization. The pause for the blood to go from the atria to the ventricles.

0.10 to 0.20 seconds

First-degree AV block

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What does the QRS complex represent?

What is the duration of the QRS complex?

Ventricular depolarization

<0.12 seconds

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What does the ST segment represent?

ST segment represents the interval between depolarization and repolarization of the ventricles.

Early stages of ventricular repolarization.

Elevation > 1mm is significant (injury/ischemia)

Confirm in 2 leads

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What does the T wave represent? What leads is it positive?

Repolarization of the ventricle

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What rhythms will have retrograde p-waves?

Junction rhythms

(Rhythm is coming from the AV node and back up to SA node)

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Why is the latter PR interval flat?

PR interval = atrial depolarization + AV nodal delay; flat portion is when atria is fully depolarized and there is no electricle current while the AV node conducts the signal (delay)

At this time there is no contraction and blood is filling the ventricles.

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What do we associate with a QRS complex wider than 0.12 seconds?

Bundle branch block

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What causes elevated T-waves?

Hyperkalemia

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When is atrial repolarization?

During QRS complex

you can see it if you alter the monitor to run the rhythm at a slower rate to uncover what the machine is not telling you

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What is the rhythm?

Sinus Rhythm

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What is the rhythm?

Sinus Bradycardia

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What is the rhythm?

Sinus Tachycardia

(100-150 bpm)

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What is the rhythm?

Junctional Rhythm
HR 40-60 bpm
Signal starts in AV node

(look for the inverted p-wave)

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What is the rhythm?

Junctional tachycardia
HR >60 bpm
Signal starts in AV node

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What is the rhythm?

PSVT bc it falls off on the latter half of the strip
(HR > 150 is SVT)

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What is the rhythm?

Premature atrial contraction

(find the underlying rhythm and then figure out the accessory rhythm and look for compensatory pause)

Example from class: PACs decrease perfusion by shortening ventricular filling time; treating them with lidocaine can worsen cardiac output due to negative inotropy without addressing the atrial ectopy.

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What is the rhythm?

A-fib

When you see AFib, immediately ask:

Is this new-onset or chronic? If unknown, TEE before cardioversion. (Clot risk >48hr)

Is the patient unstable or symptomatic enough to need cardioversion?

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What is the rhythm?

A-flutter with 3:1 ratio of P:QRS Atrial rates seen >100-150 (Sawtooth pattern) ## Footnote **Atrial flutter preserves more preload** than atrial fibrillation because atrial contraction is still organized and periodic, whereas AFib is completely chaotic with no effective atrial kick.

What is the rhythm?

**Premature ventricular contraction** Per lecture, 3 different cell types are pissed off here. 1st on appears to be a QRS from a normal conduction pathway. The second and third looks like they are from outside of the normal pathway (different parts of the ventricle). The more irregular the PVC's the worse. Usually unifocal are related to ischemia. ## Footnote Causes of PVC include hypoxemia (try supplemental oxygen) or electrolyte changes (spot check)

What is the rhythm?

1st-degree AV Block ## Footnote PRI > 0.20 seconds

What is the rhythm?

Bigeminy PVC (PVC after every other normal beat)

What is the rhythm?

Trigeminy PVC (PCV on the 3rd beat)

What is the rhythm?

2nd degree Type 1 AV Block or Wenckebach ## Footnote longer, longer, drop - now you've got a wenck-y-bach (type 1)

What is the rhythm?

2nd degree Type 2 AV Block ## Footnote fixed PRI and dropped beat

What is the rhythm?

Complete heart block or 3rd degree AVB ## Footnote fixed p to p; fixed r to r; not talking

What is the rhythm?

Vtach (150-180 bpm) | >100 bpm ## Footnote do not fixate on lead 2, look at multiple

What is the rhythm?

Vfib ## Footnote possible torsades in the middle, aka polymorphic v'tach - give Mag 2 g IV over 1–2 minutes

How do you treat V-fib?

Defibrillation (electricity)

What general anesthetics will cause sensitive myocardium?

Halothane and enflurane

How does cocaine and ketamine cause tachycardia?

Norepinephrine reuptake inhibitors ## Footnote What other meds could we think about with a similar MOA: Ephedrine (indirect sympothomimetic), St. Johns Wort (inhibit NT reuptake), Adderal (stimulate release of NTs), etc. - above are examples from class, but use your brain too ;)

What anesthetic gas can cause bradycardia in infants? What is the typical max for this drug?

Too much Sevoflurane; 1.8-2% ## Footnote Per lecture, when intubating peds this will be "cranked up" to initiate induction. If you see bradycardia in peds in other instances always think hypoxia!

What anesthetic gas can cause prolonged QT during induction?

Desflurane ## Footnote Per lecture, a dirty gas & bad for the environment

Smashing the face mask will cause pressure to build up in the eye and will result in bradycardia due to what reflex?

Oculocardiac Reflex *Five and Dime Reflex*

A local anesthetic will cause a _____________ block. Which will result in ___________.

A local anes will cause a SNS block. Which will result in severe bradycardia. ## Footnote Neuroaxial anesthesia concern. Neuroaxial means around the CNS. (e.g., spinal and epidurals)

What happens if you inject local anesthetic into the blood vessel? What is the treatment?

* Patient will become asystolic (*and so will you*) * This is becasue you get rapid systemic absorption → toxic plasma levels of local anesthetic. This hits the nerves and the heart at the sodium channels. * Treat with lipid rescue like intraplipid (Lipid emulsion absorbs lipophilic local anesthetic)

Endotracheal intubation can put pressure on the _________, resulting in bradycardia and other hemodynamic disturbances.

vagus nerve (CN X)

There can be autonomic reflexes during a surgical case stimulation of the carotid baroreceptors can cause_________.

The carotid sinus contains stretch-sensitive baroreceptors that think they are sensing high blood pressure when they’re manipulated. This causes reflex bradycardia. - Interweaving A|P: the carotid sinus is connected to herington nerve which is a branch of CN IX, glossopharyngeal nerve. Central processing for this is complete in the medulla at the NTS which will tell the CN X/vagus nerve to increase PSNS stimulation and decrease SNS outflow *Prevent this by asking the surgeon to put more local anesthetic (blocks nerve signalling) around the area or slap their hand*

During a laparoscopic case, insufflation can cause...

Bradycardia due to loss of venous return from increased intra-abdominal pressure.

Tugging the ___________ or _________ will cause bradycardia.

Peritoneum; Cervix ## Footnote Cervical vasovagal shock is termed as stimulation either by instruments or products of conception at cervical os results into bradycardia and hypotension.