ECG Interpretation, Summaries of Pathology

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ECG Interpretation

Part 2

Junctional Rhythms

Junctional Escape Rhythm

Junctional Escape Rhythm

 AV node or junction is pacemaker

 Atria are depolarized through retrograde conduction

 Ventricles depolarize normally

 Rate _____________ (can be accelerated, >60)

 Retrograde P wave can occur before, during, or after QRS

complex, depending on its site of origin in the AV node

 PR interval is variable, depending on the site of origin

 QRS ___________________

4 Junctional Escape Rhythm REGULAR - RATE - P WAVES - PRI - QRS -

Bundle Branch Blocks 8 Bundle Branch Blocks

 Right and left bundle branches send the electrical impulse

to the right and left ventricle simultaneously

 When the bundle branches are functioning normally, the

right and left ventricles contract at the same time

 BBB occurs when one of the

bundle branches becomes

diseased or damaged, and

stops conducting electrical

impulses; that is, a bundle

branch becomes “blocked”

Bundle Branch Blocks

 As the electrical impulse leaves the Bundle of His, it

enters good Bundle Branch only, and is carried to the

corresponding ventricle

 Then, from that ventricle, the electrical impulse finally

makes its way to the other ventricle

 As a result, the two ventricles no longer receive the

electrical impulse simultaneously

 First one ventricle receives the electrical impulse,

then the other

10 Bundle Branch Blocks

 Rhythm -

 Rate -

 QRS duration –

 P Wave –

 P Wave rate -

 P-R Interval -

Identify BBB

 Diagnosing both kinds of blocks requires looking in the

same leads

 However, the QRS will look much different in the 2 blocks

 QRS complex, for both blocks, has to exceed a duration of

greater than or equal to 0.12 sec (3 small boxes)

14 RBBB

 First look in leads ___________________

 QRS complex has two R-waves  “rabbit ears”

 Next look in leads ___________________

 S wave has a “slurred” appearance

RBBB 16 RBBB

LBBB 20 Bundle Branch Block

 Treatment

 heart depends on the bundle branches  without them, the electrical impulse is not delivered to the ventricles  block in both bundle branches, therefore (a condition called complete heart block) can be fatal but is rare  if RBBB or LBBB is accompanied by syncope  _________  block of both BB  ___________________

Ventricular Rhythms

Idioventricular Rhythm

Ventricular Tachycardia

Ventricular Fibrillation

Torsade de Pointes

Premature Ventricular Contraction

22 Ventricular Rhythms RHYTHM REGULARITY RATE P WAVES PRI QRS Idio- ventricular regular 20-40 none none >0.12 sec wide, bizarre Vent Tach usually regular 100-250 none associated none associated

0.12 sec wide, bizarre Vent Fib no organized rhythm no organized rhythm

no organized rhythm no organized rhythm no organized rhythm PVC interrupts underlying rhythm depends on underlying rhythm none none >0.12 sec wide, bizarre

Ventricular Tachycardia REGULAR - RATE - P WAVES - PRI - QRS - 26 Ventricular Tachycardia (Monomorphic)

Ventricular Tachycardia (Polymorphic) = torsade de pointes 28 Ventricular Tachycardia

 Results from abnormal tissues in the ventricles generating

a rapid and irregular heart rhythm

 coronary artery disease  hypokalemia  cocaine use

 Poor cardiac output is usually associated with this rhythm

thus causing the patient to go into cardiac arrest

 If loss of consciousness, hypotension, no pulse -

 _____________________________________

 If hemodynamic status is stable + no evidence of coronary

ischemia or infarction --> rhythm conversion

 _____________________________________

Ventricular Fibrillation

 Causes (con’t)

 metabolic or toxic  electrolyte disturbances and acidosis  medications or drug ingestion  environmental poisoning  sepsis  neurologic  seizure  cerebrovascular accident (intracranial hemorrhage or ischemic stroke)  drowning 32 Ventricular Fibrillation

 Treatment

 prehospital care is vital for arrests due to VF that occur outside the hospital  witnessed or early recognition of an arrest  early activation of emergency medical services (EMS) system  bystander CPR slows the degeneration of VF and improves survival  automated external defibrillator (AED) application and defibrillation by trained personnel in the field  early access to trained EMS personnel capable of performing CPR, defibrillation, and advanced cardiac life support (ACLS)

Ventricular Fibrillation  Treatment  hospital care (ACLS) = SCREAM S Shock 360J monophasic, 200J biphasic, 1st and subsequent shocks. (Shock every 2 minutes if indicated) C CPR After shock, immediately begin chest compressions followed by respirations (30:2 ratio) for 2 minutes. (Do not check rhythm or pulse) R Rhythm Rhythm check after 2 minutes of CPR (and after every 2 minutes of CPR thereafter) and shock again if indicated. Check pulse only if an organized or non- shockable rhythm is present. 34 Ventricular Fibrillation E Epinephrine 1 mg IV/IO q3-5 min. Or vasopressin 40 U IV/ IO, once, in place of the 1st or 2nd dose of epi. AM Antiarrhythmic Medications Consider antiarrhythmics: Amiodarone 300mg IV/IO, may repeat once at 150mg in 3-5 min. if VF/PVT persists or Lidocaine (if amiodarone unavailable) 1.0-1. mg/kg IV/IO, may repeat X 2, q5-10 min. at 0.5-0.75 mg/kg, (3mg/kg max. loading dose) if VF/PVT persists, or Magnesium Sulfate1-2 g IV/IO diluted in 10mL D5W (5-20 min. push) for torsades de pointes or suspected/ known hypomagnesemia.

Premature Ventricular Contractions

 Single PVC poses no problems, but may signal serious

problems

 Causes for concern

 increased frequency (> 6/minute)  multifocal  couplets  salvos  R-on-T phenomenon 38 Premature Ventricular Contractions REGULAR - RATE - P WAVES - PRI - QRS -

Premature Ventricular Contractions

 ___________________

40 Premature Ventricular Contractions

 ___________________