EKG Basics and Cardiac Conduction

A recording of the heart's electrical activity as it progresses through the cardica cycle

Dr Willem EInthoven developed cardiography in 1901

Electrical depolarization is muscle contraction - actiation of muscle cells
Electrical repolarization is recovery before the next contraction
Cardiac cycle is 1 beat

The lead is an electrical view point, the electrode is the sensor placed on the body

Small box: 0.04 sec, 1mm
Large box: 0.2 sec, 5mm
Paper speed: 25 mm/second

SA node -> both atria depolarize -> Bundle of His -> Right and left bundle branches -> purkinje fibers and terminal filaments (ventricular activation)

The AV node delays the electrical signal breifly so the atria can contract and help fill the ventricles before ventricular contraction

P: atrial depolarization
PR interval: conduction from atria through AV conduction system toward ventricles
QRS complex: ventrical depolarization
ST segment: period following ventricular depolarization when ventricles are electrically activated
T wave: ventricular repolarization
QT interval: total time for ventricular depolarization and repolarization

V1: 4th intercostal space, right sternal boarder
V2: 4th intercoastal space, left sternal boarder
V3: Midway between V2 and V4
V4: 5th intercoastal space, midclavicular line
V5: level with V4, anterior axillary line - has highest R wave
V6: Level with V4, midaxillary line

V1,V2: right ventricle
V3,V4: interventricular septum
V5,V6: Left ventricle

Horizantal/transverse plane

Start, 300, 150, 100, 75, 60, 50, 43, 37, 33, 30
On a 12 lead EKG,, use two consecutive QRS complexes from same lead

An arrythmia s a disturbance in the normal electrical sequence of heart activity
An irritable focus is a cell or group of cells generating abnormal electrical impulses

Originate from irritable focus in atria
- cause an early beat, altered p wave, generally narrow/normal QRS

Atrial flutter:
- 250-350 bpm, sawtooth flutter waves, repetitive atrial depolarizations
atrial fibrillation:
- many abnormal atrial electrical impulses, no distinct p waves, irregular R-Rintervals

Originate in ventricles, premature wide QRS, usually no preceding sinus P wave

Ventricular tachycardia:
- 150-250 bpm, consecutive wide QRS, impaired perfusion/deterioration
V-fib: chaotic ventricular electrical activity, no organized QRS, no effective ventricular pumping, cardiac arrest rythm, requires CPR, AED
Asystole: absence of organized, detectable ventricular electrical activity, flat line

Treat patient, not just the monitor -> responisveness, pulse, bp, skin, etc

Warmup - 5-10min - 30-40% VO2 or HR reserve, dynamic stretching
Conditioning: 20-60 min continuous or in 10 min bouts
Cool down - 5-10min, prevents pooling, BP drops
Stretching - 10min, static

Frequency
Intensity
Time
Type
Volume Progression

Moderate - 5 days/week 30-60 min
Vigorous - 3 days per week 20-60 min
Minimum is 150 mins moderate or 75 mins vigorous

Light - 30-39% HRR or VO2R
Moderate - 40-59%
Vigorous - 60-89%