EKG Flashcards
Types of cardiac cells
- Pacemaker cells
- Electrical conducting cells
- Myocardial cells
Pacemaker cells
SA node
AV node
Electrical conducting cells
*Transmit currents quickly and effectively Anterior, posterior, middle fascicles Bundle of HIS Left Bundle Branch Right Bundle Branch Purkinje Fibers
Characteristics of myocardial cells
Transmits current slow
Contract and pump blood out of heart
Can initiate heart beats if the SA node fails or if the myocardium gets irritated
Cardiac conduction pathway
- Sinoatrial (SA) node
- Internodal fascicles
- Atrioventricular (AV) node
- Bundle of HIS
- Right Bundle Branch
- Left Bundle Branch
- Purkinje Fibers
5 large boxes = ?? time
1 second
300 large boxes = ?? time
1 minute
P wave characteristics
Atrial depolarization
Normal duration <120 ms (3 small boxes)
Upright P wave characteristics
Normal
Beat originated from SA node or atria and traveled antegrade (down the normal pathway)
Inverted P wave characteristics
Beat originated in AV node
Depolarizes atria in retrograde
Junctional beats
Absent P wave characteristics
Originates in the ventricular myocardium
Only the ventricles depolarize
Can occur in afib or junctional rhythm as well
Narrow QRS complex
Absent or inverted P wave
Junctional rhythm
Wide QRS complex
Absent P wave
Ventricular rhythm
Absent P wave
Narrow QRS complex
Irregular rhythm
Afib
Ventricular depolarization
QRS complex
Normal <120 ms
Slow depolarization, likely coming from the ventricular myocardium
Wide QRS
Potential causes of wide QRS complexes
- The myocardium gets irritated (common with pH imbalance, caffeine, stress, ischemia, electrolyte abnormality
- The ventricles must take over as the pacemaker
- Wolf Parkinson White Syndrome (WPW)
- RBBB/LBBB
Ventricular repolarization
T wave
<5 mm height in leads I, II, III
When would you see a U wave?
With hypokalemia
The point at which the S wave returns to baseline
the J point
Upward slurring of the Q wave, commonly seen with WPW syndrome
Delta wave
J wave
“bump” on the S wave. Commonly seen with hypothermia
Normal PR interval start, end and time
Starts at the beginning of the P wave and ends at the start of the Q wave
120-200 ms
Normal QT interval start, end and time
Starts at the Q wave, ends at the end of the T wave
400-440 ms
May cause prolonged QT
Zofran and Phenergan
Characteristics of PR segment
“pause” at the end of atrial depolarization to allow blood to fill the ventricles
starts at the end of the P wave and ends at the beginning of the Q wave
Start and end of ST segment
Starts at the J point, ends at the start of the T wave
a heart beat that happens before it is expected to
premature beat
a heart beat that comes after a long pause
escape beat
What happens during systole?
Heart contraction
Aortic valve opens and the valve leaflets close off the blood supply to the coronary arteries
Blood is ejected from the L ventricle and organs are perfused
What happens during diastole?
The heart relaxes, aortic valve closes, blood rushes into the coronary arteries to perfuse the heart
True/false: The faster the heart rate, the better coronary perfusion
False. The slower the heart rate, the longer the time that the coronary arteries are open, the greater the diastolic filling time and the better coronary perfusion
True/false: Stroke volume is reduced when ventricular filling is reduced
True
Describe active vs passive ventricular filling
Active filling occurs when the atria contract and force blood into the ventricles
Passive filling is when the atria don’t contract and the volume entering the ventricles is much lower
Heart conditions that can reduce ventricular filling
- When a heart beat occurs without atrial contraction (No P wave); afib, escape ventricular rhythm
- When there is a premature heartbeat (PAC, PVC)
- Rapid HR (SVT or Vtach)
Detects the electrical difference/voltage between two limbs
EKG leads
Provides a picture of the heart from a 0-180 degree angle
Lead I
Provides a picture of the heart from a 60 degree angle
Lead II
Provides a picture of the heart from a 120 degree angle
Lead III
Limitation of a 3 lead EKG
Not as sensitive for detecting myocardial ischemia in the L ventricle
Where is lead I located?
R arm (-) to L arm (+) White to black
Where is lead II located?
R arm (-) to L foot (+) White to red
Where is lead III located?
L arm (-) to L foot (+) Black to red
The neutral/ground lead in a 5 lead EKG
Green
Precordial lead in a 5 lead EKG that makes it more sensitive to pick up myocardial ischemia in the L ventricle
Brown (V5)
Heart rate is faster during inspiration and slower during expiration
Irregular sinus rhythm
How does your HR increase during inspiration?
Intrathoracic pressure decreases and preload increases
How does your HR decrease during expiration?
Intrathoracic pressure increases and preload decreases
EKG description of sinus tachycardia
P wave present
>100 bpm
Etiologies of sinus tachycardia
Hypovolemia/hypotension
Pain/light anesthesia
Anesthetic concerns for sinus tach
Increased cardiac oxygen demand
Decrease cardiac oxygen supply
Possible hypovolemia
Treatment for sinus tachycardia
Fluids
Deepen anesthetic
Beta blocker
EKG description of sinus bradycardia
P wave present
<60 bpm
Benefits of sinus bradycardia
- Healthy patients that exercise regularly (typically have higher stroke volume)
- Patients with CAD (increased oxygen supply, decreased oxygen demand)
Anesthetic concerns for bradycardia
- Age of the patient (particularly kids)
- Severity of bradycardia
- How fast the heart rate drops
Treatment for sinus bradycardia
- Robinul, atropine, epinephrine
2. Pacemaker (temporary transcutaneous pacing or permanent implantable pacemaker)
Slow, complex rhythms that precede asystole
Agonal rhythm
True/false: You should defibrillate patients in asystole
False! Perform CPR, administer Epinephrine and treat any reversible causes
EKG description of pulseless electrical activity (PEA)
EKG strip shows electrical activity but the patient has no pulse
Physiology of PEA
- The heart does not contract
2. There is an insufficient cardiac output to generate a pulse and supply blood to the organs
Treatment for PEA
- CPR
- Epinephrine administration
- Treat any reversible causes
NOT DEFIBRILLATION
Any heart beat that originates outside the SA node
Ectopy
Types of ectopy
- Premature beats
- Supraventricular ectopic rhythms
- Escape beats
- Ventricular ectopic rhythms
EKG description for PACs
- Upright P wave
2. Normal/narrow QRS complex
Physiology of premature beats
The specific myocardium was irritated (atrial, junctional or ventricular) and decided to initiate a heartbeat prior to the signal from the SA node
Anesthetic concerns for premature beats
No concern unless they occur frequently due to less ventricular filling/low stroke volume/cardiac output
EKG description of PJC
Missing or inverted P wave
Normal QRS complex
EKG description of PVC
No P wave
Wide, “bizzare/different” QRS complex
Treatment of PVCs
- Antiarrhythmics (lidocaine, amiodarone)
2. Robinul, atropine
EKG description of junctional escape beat
- Inverted or absent P wave
- Normal/narrow QRS complex
Occurs after a long pause
Physiology of escape beats
SA node fails temporarily, atrial, AV or ventricular nodes jump in for one beat before the SA node starts working again
Atrial will take over first, then AV, then ventricular
Anesthetic concerns with escape beats
If it occurs multiple times or pauses are prolonged, consider robinul/atropine/pacing
EKG description for ventricular escape beats
- Long pause followed by wide QRS complex
2. No P wave
EKG description for aflutter (atrial flutter)
- “Saw tooth pattern” 250-350 P waves/min
2. More P waves than QRS complexes
Physiology of aflutter
Atrial myocardium is contraction regularly at 250-350 times/min
Causes decreased ventricular filling and decreased cardiac output
AV node blocks impulses to control heart rate, leading to ventricular rate being slower than atrial rate
Anesthetic concerns for aflutter
- Ventricular filling and cardiac output is reduced
- Heart is burning more oxygen than normal
Needs evaluated by cardiologist first
Treatment for aflutter
- Medications (Amiodarone, Sotalol, Digoxin)
2. Synchronized cardioversion
Difference between pacing and cardioversion
Pacing treats unstable slow rhythms while cardioversion/defibrillation treats unstable fast rhythms
EKG description of atrial fibrillation (afib)
No P waves
Irregularly irregular rhythm
Physiology of afib
Atria are chaotically “quivering” up to 500 atrial impulses/min
Clinical implications of afib
- Risk of clot formation in L atrium increases
2. Cardiac output can be decreased by 25-30% and can be decreased even more if ventricular rate is too fast
Anesthetic concerns of afib
Only with acute onset
Treatments for afib
Synchronized cardioversion
Medications (adenosine)
Blood thinners to prevent clots (if afib has been present for more than 2 days, they need anticoagulation for 3 weeks before cardioversion and for 4 weeks after)
EKG description for junctional rhythm
Inverted or absent P wave
Normal QRS complex
Regular rate
Normal junctional rhythm (bpm)
40-60 bpm
Accelerated junctional rhythm (bpm)
60-100 bpm
Junctional tachycardia (bpm)
> 100 bpm
Physiology of junctional rhythm
SA node isn’t working, so the AV node takes over
Atrial contraction is slightly delayed
Anesthetic concerns with junctional rhythms
Less ventricular filling, can be concerning with low BP
May convert to sinus after Robinul
EKG description of SVT
- HR >150 bpm
- Normal QRS complex
- Difficult to differentiate between sinus and junctional
Anesthetic concerns with SVT
Decreased ventricular filling. Should treat promptly
Treatment of SVT
- Vagal maneuvers
- Adenosine
- Synchronized cardioversion
EKG description for ventricular escape rhythms
- No P wave
- Wide QRS complex
- Slow heart rate <60 bpm
Physiology of ventricular escape rhythms
- Both the SA node and AV node have failed
2. Ventricular myocardium starts initiating beats
Anesthetic concerns with idioventricular rhythm
- There is no active ventricular filling
- Low HR
- Low cardiac output
Treatment for ventricular escape rhythm
- Cardiac pacing
- Potentially epinephrine if pt is unstable
AVOID LIDOCAINE (it suppresses ventricular ectopy)
Rates of idioventricular rhythm, accelerated idioventricular rhythm and vtach
- <60 bpm for idioventricular rhythm
- 60-100 bpm for accelerated idioventricular rhythm
- > 100 bpm for vtach
EKG description for monomorphic vtach
- No P waves
- Wide QRS complexes of the same shape
- Heart rate >100 bpm
EKG description for polymorphic vtach (Torsades de Pointes)
R wave alternate in polarity and amplitude
Prolonged QT interval
Physiology of vtach
Ventricular myocardium is initiating beats at a rapid rate, which leads to:
- High oxygen consumption
- Minimal ventricular filling (may or may not produce pulses)
Anesthetic concerns with vtach
Medical emergency!!!
Requires immediate cardioversion/defibrillation
Treatment of vtach
Antiarrhythmics (amiodarone, lidocaine)
Electrical cardioversion
EKG description for ventricular fibrillation
No real P waves or QRS complexes
Scribbles
Physiology of Vfib
Ventricles are not contracting, only quivering at a rapid rate
- Heart is consuming a lot of oxygen
- There is no pulse or cardiac output
Anesthetic concerns with vfib
Immediate defibrillation!!!!
Treatment for vfib
- Defibrillation
2. CPR until perfusing rhythm returns
EKG description for 1st degree AV block
Prolonged PR interval (>0.2s, or one large box)
Physiology of 1st degree AV block
For some reason conduction through AV node is slower than normal
Anesthetic concerns with 1st degree AV block
Not really
EKG description of 2nd degree AV block
Dropped QRS complexes Type I (Wenckebach): Increasingly longer PR intervals Type II: Constant PR interval
Physiology of Type I 2nd degree AV block
Partial block within the AV node that’s bad enough to completely block some of the impulses going through
Physiology of Type II 2nd degree AV block
A block below the AV node (within the Bundle of His or the bundle branches) that’s bad enough to completely block the impulses
Anesthetic concerns with 2nd degree AV block
Yes, concerning. May require cardiac pacing
EKG description for 3rd degree AV block
P waves and QRS complexes are not associated with each other
Slow ventricular rate (30-40bpm)
Physiology of 3rd degree AV block
Atria are contracting, but the AV node is blocked and no impulses are coming through
The ventricles must initiate their own beat
Clinical effects of complete heart block
- The atria may try to empty into full ventricles
- Ventricles may attempt to contract when empty
- Serious reduction in cardiac output
Treatment for complete heart block
- Cardiac pacing
- Epinephrine if pt is unstable
AVOID LIDOCAINE
Signs of ischemia/infarction
- ST segment changes (depression is more ischemia, elevation is more infarction)
- Abnormal T waves
- Abnormal Q waves
Myocardial ischemia treatment
- Increased oxygen supply
2. Decrease oxygen demand
Anesthetic concerns with signs of ischemia/infarction
Compare to old EKGs, if acute onset, very concerning