Andy Rodriguez

Ventricular Rhythms

• Impulse is generated in the ventricles. Generally recognized by wide QRS complex, >0.12

Premature Ventricular Contraction (PVC)

• Regular – ectopics will interrupt
• Rate – depending on underlying rhythm
• No P wave before PVC
• Wide QRS >0.12
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Compensatory Pause

• Allows for heart pick up its rhythm again after a PVC, resumes normal rhythm as was before PVC
• 2x R-R
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Interpolated

• R-R stays the same and PVC is between normal R-R
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Types of PVCs

• Unifocal – One focus generating the extra beat, generates PVCs that look exactly the same
• Multifocal – Multiple foci generating extra impulses. generates PVCs that look different

R on T Phenomenon

• PVC hits during or end of T wave, can cause Vfib if hits just right
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PVC Couplets

• Two PVCs in a row
• May be unifocal or multifocal

PVCs in a run or Run of PVCs

• More than three PVCs in a row
• Also called a “run of vtach”

PVC Groupings

• 1:1 Ratio – Bigeminy (every other is a PVC)
• 2:1 Ratio – Trigeminy (every third is a PVC)
• 4:1 Ratio – Quadgeminy (every fourth is a PVC)

Ventricular Tachycardia

• Usually Regular – can be slightly irregular
• Rate of 150 – 250 (Less than 150 is slow VT, greater than 250 V flutter)
• No P waves
• PRI – None
• QRS- wide and bizarre >0.12
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Ventricular Fibrillation

• Multiple foci firing in an uncoordinated fashion
• Grossly irregular
• Wide QRS – Fibrillating
• No pulse
• Shockable Rhythm
• Most lethal rhythm
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Idioventricular Rhythm

• Regular rate at 20-40 BPM (above 40 -120 called an accelerated idioventricular rhythm)
• No P waves
• No PI
• QRS wide and bizarre
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Asystole

• Absence of any electrical activity

Andy Rodriguez

Impulse is generated somewhere near the AV node. Impulses can travel up or down causing absent or inverted P wave – sometimes after the QRS. QRS is normal and tight.

Premature Junctional Contraction (PJC)

• Irritable site in AV junction fires prematurely producing a single ectopic beat.
  • Regularity depends on underlying rhythm
  • Rate – same
  • P Wave: Inverted, can fall before, during or after QRS
  • PRI, if measurable, <.12
  • QRS <.12
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Junctional Escape Rhythm

• Higher pacemaker sites fall and AV junction takes over, atria are depolarized via retrograde conduction. Ventricular conduction is normal.
  • Regular
  • Rate: 40-60
  • P Waves, inverted, during or after QRS
  • PRI – only if there is a P wave and before and will be <.12
  • QRS <.12
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Accelerated Junctional Rhythm

• Irritable focus in the AV junction fires repeatedly at a rate faster than the SA node. Retrograde conduction to atria and conduction to ventricles is normal
• Regular
• Rate: 60-100
• P Wave: inverted, before or after QRS
• PRI – only if there is a P wave and before and will be <.12
• QRS <.12
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Junctional Tachycardia

• Irritable focus in the AV junction fires repeatedly at a rate faster than the SA node. Retrograde conduction to atria and conduction to ventricles is normal
• Regular
• Rate: 100-180
• P Wave: inverted, before or after QRS
• PRI – only if there is a P wave and before and will be <.12
• QRS <.12
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Supraventricular Tachycardia (SVT)

• Rapid, Regular, SV rhythm that is so fast that you cant see P waves. Normal QRS
• Rate >150
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Paroxysmal Supraventricular Tachycardia (PSVT)

• A short burst of SVT that occurs in a rhythm strip
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More on EKGs… Andy Rodriguez

Escape Mechanism – normal pacemaker slows down or fails and a lower pacing site assumes pacemaking responsibility.

Sympathetic – both Atria & ventricles
Parasympathic – Only Atria

Analyzing the rhythm

• Regularity – Rhythm
  • regular
  • irregular
  • pattern to irregularity
  • ectopic beats
• Rate
• P Waves
  • present
  • regular, one for every QRS
  • before QRS or after
  • deflection – normal and upright in lead II
  • all P waves look alike
  • are irregular P waves associated by ectopic beats
• PR Intervals (PRI)
• QRS Complex
  • equal duration
  • measurement
  • normal limits
  • all look alike?
  • are unusual QRS complexes associated with ectopic beats?

Sinus Rhythms

Normal Sinus Rhythm – Regular, 60-100 BPM, P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12

Sinus Bradycardia - Regular, Rate <60 BPM, P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12

Sinus Tachyardia - Regular, Rate >100 BPM (usually 100-160), P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12

Sinus Arrhythmia – sinus node fires faster during inspiration and slower during expiration. rate is still normal, and still normal QRS –
Irregular, 60-100 BPM, P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12

Atrial Rhythms

Wandering Pacemaker – pacemaker site wanders between SA node, atria and AV node. rate is usually normal and will conduct normally to ventricles
Slightly Irregular, 60-100 BPM, P wave morphology changes from beat to beat, one before every QRS, PRI 0.12-0.20 but may vary, and QRS <0.12

Premature Atrial Contraction (PAC) – irritable focus within atrium that fires prematurely and produces a single ectopic beat. impulses are conducted normally.
Usually regular (depending on underlying rhythm) except for PAC, 60-100 BPM, P wave changes – one that comes early looks different than normal sinus P waves, one before every QRS, PRI 0.12-0.20 but may be longer, and QRS <0.12

Atrial Tachycardia (or SVT)– Single atrial site fires repetitively at a very high rate. impulses conducted normally
Regular 150-250 BPM, P wave looks different than sinus p wave if visible at all, one before every QRS, PRI not measurable, QRS <0.12

Atrial Flutter -  single focus initiates rapid repetitive impulses, AV node protects ventricles by blocking conduction of some impulses. Atrial Rhythm- regular, several flutter waves (saw tooth)before each QRS (F waves), PRI unable to determine, atrial rate 250-350 bpm

Atrial Fibrillation – multiple foci initiate rapid repetitive impulses, AV node protects ventricles by blocking conduction of some impulses.
Grossly irregular, atrial rate >350 bpm, ventricular rate varies greatly, no discernable P waves, no PRI, QRS <.12

Steve Kanarian

Some cardiology review:

• Location of Heart: Retrosternal
• Point of maximal impulse, Left 5th intercostal, midclavicular line, above mitral valve as well.
• Pericardium contains approx 30cc of fluid
• CO= SV x HR
• Frank Starling Law – (use fluid challenge to increase CO, increase in volume = increase in stretch therefore increase CO)
• S1 – closing of mitral and tricuspid valves
• s2 – closing of pulmonic and aortic valves
• s3 – murmur, caused by ventricular filling, caused by left sided CHF
• s4 – sign of CHF
• Coronary Vessels come off base of aorta and come back via the coronary sinus
  • right coronary artery (RCA) (right atrium and ventricle)
  • left coronary artery (LCA) splits; (mostly left ventricle and atrium)
    • left anterior descending
    • circumflex coronary
• Preload; pressure in ventricle at diastole
• Afterload; pressure against which heart has to pump

Depolarization causes contraction.(Na+ rushes in) Repolarization is the refractory state. (K+ left in the cell)

Cardiac Physiology

(Bundle of Kent – Wolf Parkinson’s White –WPW)

EKG Lead Placement

• Bipolar (Limb) Leads – impulses traveling towards positive lead, upright wave, going towards negative lead, points down
• Augmented (Unipolar) Leads – Boosted Electrically)
• Precordial (Chest) Leads- V1-V6 (Septal 1,2, Anterior 3,4 Lateral 5,6 Inferior 2,3, aVF) SALI

Electrical Conductivity and the EKG

‘Monitoring’ leads are not diagnostic, 12 Lead EKG Machines are diagnostic quality

ECG Paper

• Speed (horizontal Boxes smallest= .04 sec, big box is .20 sec)
• Amplitude – Vertical box = 0.1mV height  (1mm)

Normal Electrocardiogram

• P-R Interval (PRI) – 0.12 – .20 sec (Prolonged PRI indicates Heart block)
• QRS – <0.12 sec – wider indicates rhythm below AV node
• QT interval – Q wave to repolarization – prolonged means heart is at risk for ventricular dysrythmias (poisoning, overdoses)

5 points to look for

• Rate
• Rhythm
• P waves
• PRI
• QRS