ELECTROCARDIOGRAMs ECGs Material to be Covered ACSMs Resource
ELECTROCARDIOGRAMs (ECGs)
Material to be Covered − ACSM’s Resource Manual for Guidelines for Exercise Testing and Prescription (6 th ed. ) − Chapter 27 − Rapid Interpretation of EKG’s (6 th ed. )
LEAD PLACEMENT Standard 12 -lead ECG: • Limb Leads - 6 in all - I, III, a. VL, a. VR, a. VF • Chest leads - 6 in all -V 1, V 2, V 3, V 4, V 5, V 6
LIMB LEADS Bipolar - Augmented - - III a. VR + + + II + a. VF a. VL
CHEST LEADS Along the horizontal plane: • V 1 and V 2 - Right side of the heart • V 3 and V 4 - Intraventricular septum • V 5 and V 6 - Left side of the heart
PROCESS SA Node - Heart pacemaker; located in the RA; initiates next step
PROCESS P Wave - Atrial depolarization and contraction
PROCESS AV Node - Slows the depolarization of the atria; connects atria and ventricles electrically
PROCESS QRS complex - ventricular depolarization; begins in Bundle of His
PROCESS
VENTRICULAR DEPOLARIZATION His Bundle Left Bundle Branch & Right Bundle Branch Purkinje Fibers
VENTRICULAR DEPOLARIZATION • Q Wave - 1 st downward wave of the complex • R Wave - 1 st upward wave of the complex • S Wave - downward wave preceded by an upward wave
PROCESS ST Segment - Initial plateau phase of ventricular repolarization
PROCESS T wave - Rapid phase of ventricular repolarization
NORMAL ECG
RHYTHM Normal sinus rhythm: • Each P wave is followed by a QRS • Regular or irregular
RATE • P wave rate 60 - 100 bpm with <10% variation - Normal • Rate < 60 bpm = Sinus Bradycardia - Results from: - Excessive vagal stimulation - SA nodal ischemia (Inferior MI) • Rate > 100 bpm = Sinus Tachycardia - Results from: - Pain / anxiety - CHF - Volume depletion - Pericarditis - Chronotropic Drugs (Dopamine)
RATE Methods: • Method 1 = 1500/ # of small boxes between RR • Method 2
P WAVE Normal: • Height < 2. 5 mm in lead II • Width < 0. 11 s in lead II
P WAVE ABNORMALITY
How to read the ECG – Look at the whole tracing. Rhythm: Is there a P wave before each QRS complex? − Yes: sinus rhythm No: AV junctional or heart block Rate: Count boxes; use caliper, ruler PR interval: Normal - 0. 20 sec. or less QRS complex: Skinny (0. 10 sec. or less) or broad (BBB or ventricular) ST segment: Isoelectric (normal), elevated or depressed T wave: Upright, flat or inverted Interpretation: Normal or abnormal. − Is the rhythm dangerous?
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