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Normal Conduc- tion System
-SA Node = Primary Pacemaker of the Heart, rate of 60-100 bpm -Internodal Pathways = Pathways connecting SA Node and AV Node -AV Node = Backup pacemaker, rate of 40-60 bpm -Bundle of His = splits nerve fibers down Left & Right Sides, His-Purkinje is conduction system of heart -L & R Bundle Brancehs = lead to left & right of the myocardium -Purkinje Fibers / Network = ends of the muscle, last escape pacemaker sites rate of 14-
- Tele Strip Paper -Small box = 0.04 sec -Large boxes = 5 x 5 small boxes, 0.20 sec
- SA Node Rate 60-100 bpm
- AV Node Rate 40-60 bpm
- Ventricles / Purk- inje Fibers Rate
- Tele Tracing Waves
20-40 bpm
P-wave -PR-Interval (PRI) = 0.12 - 0.20 sec -QRS complex = 0.08-0.12 sec T-wave Q-wave U-wave
- Normal PRI 0.12-0.20 sec (3-5 small squares)
-Indicates AV conduction time -Measure from P wave start to QRS wave -Consider heart blocks if abnormal
- Normal Etiology SA Node
- Tele Tracing QRS Complex
- Normal QRS Complex
Firing of SA Node causing depolarization of Atria. The im- pulse travels from SA node, through internodal pathways to AV node, where it is delayed for short amount of time. (PRI)
Q-Wave = 1st Negative Deflection R-Wave = 1st Postive Deflection S-Wave= Negative Deflection following R-Wave
0.08-0.12 sec (2-3 small squares)
Duration of this will lengthen when electrical activity takes a long time to travel through the heart. Normal conduction, AV node -> His-Purkinje system -> fast duration of this complex
Consider BBB or Ventricular origin if higher
- Q-T interval 0.35 - 0.43 sec
- Heart rate bradycardia < Normal 60- tachycardia <
- Tele tracing mea- surements
HR
PR Interval QRS Complex Regularity
- Sinus Arrhyth- mia
- Junctional Rhythms (AV Node/Junction)
- Junctional Rhythm Pathophysiology
- Junctional Rhythm ECG Presentation
- Junctional Es- cape Rhythm
- Accelerated Junctional Escape Rhythm
- Premature Junc- tional Contrac- tions (PJCs)
Rate: Varies P-Waves: 0.12-0. Regularity: Irregular R-R
-Junctional Escape -Premature Junctional Contraction (PJCs) -Accelerated Junctional Rhythm
SA node does not control the heart's rhythm, may be a block in pathway. AV node takes over as pacemaker. Atria still contract before ventricles d/t backwards conduction of AV to atria.
-Usually with lost P wave or inverted P wave, closer to QRS -May have Retrograde P wave (depolarization from the AV node back to the SA node) -Narrow PRI
-Rate: 40-60 bpm b/c AV as backup pacemaker, beats late in timining -P-waves: Inverted, following QRS, or lost -QRS 0.10 sec or less -Rhythm: Regular -Narrow PRI <0.
-Rate: >60 bpm bc AV fires above this -Same as Junctional Escape
-Random, early Junctional beats -QRS 0.10 sec or less -Typically followed by a long, compensatory pause
- PJC vs Junction- al Escape beat
- Ventricular Rhythms
- Idioventricular Rhythm
- Accelerated Idioventricular Rhythm
- Premature Ven- tricular Complex (PVC)
-Idioventricular Rhythm / agonal (~20-40) -Accelerated Idioventricular rhythm (60-100) -Premature Ventricular Complex -Ventricular Tachycardia > -Ventricular Fibrillation -Torsades de Pointes
-Rate: <50 bpm, slow -Impulses originating from the ventricles, escape p, no SA/AV impulse -Indicates ventricles producing escape beats -No P-waves -Wide QRS >0.
-Rate: 50-100 bpm When 3 or more ventricular beats appear in sequence. Same rules as idioventricular except faster rate. -QRS wide >0.
Occur when a ventricular site generates an impulse before next regular sinus beat. Frequent PVC's may cause heart to skip a beat. -Wide QRS -QRS shape can be WIDE & bizarre -No P wave -Bigeminy, Trigenminy, Quadrigeminy types -Couplet (2 PVCs consecutive) -Triplet (3 PVCs consecutive)
-No HR -Emergency condition
- Torsades de Pointes
-Type of VT -"corkscrew" appearance -QTc prolong pt (like those on antipsychotics, are at risk) -Mg is the antidote -QRS complexes vary in shape and amplitude & appear to wind around baseline
- Atrial Rhythms -Atrial Fibrillation (Afib) -Atrial Flutter / AF RVR -Wandering Atrial Pacemaker -Multifocal Atrial Tachycardia
- Atrial Fibrillation (Afib)
- Atrial Flutter (AFlutter)
- Multifocal Atri- al Tachycardia (MAT)
-No P waves Atria quiver, fibrillatory waves. Fast firing. -Irregular Ventricular Beats (R to R) -Rate >100 is Afib with Rapid Ventricular Response
-Classic "Saw tooth pattern" -Often regular (d/t typical 4:1 atrial pulses ratio), but can be irregular
When many non-SA sites firing impulses. -Rate: >100 bpm -P-waves vary in shape, see at least 3 dif. types -PRI varies -Ventricular rhythm is regular (R to R)
- Wandering Atri- al Pacemaker (WAP)
- Premature Atri- al Contractions (PACs)
- SupraVentricular Tachycardia (SVT)
-Similar to MAT but Rate <100 bpm -P waves present & vary in shape (at least 3 dif.) -Irregular atrial rhythm, regular ventricular rhythm
early beats with similar P-waves, see compensatory pause
-Narrow QRS complex (means impulse originates above the ventricles) -Rate >150 bpm see lost P waves *ST is 100-150 usually
- ST vs VT -VT rate >100, impulses originate from ventricles -VT has wide QRS d/t origination in the ventricles
- Heart Blocks -First Degree AV Block -Second degree, Type 1 (Mobitz 1 / Wenkebach) -Second degree, Type 2 (Mobitz 2) -Third Degree / CHB -Bundle Branch Block
- First Degree AV Block
- Second Degree AV Block, Type 1
- Second Degree AV Block, Type 2
-PRI prolongation >0. *All PRI measurements are the same, all are conducted -P-waves before every QRS
-PRI longer & longer, until QRS dropped
-Dropped QRS, no prolongation
