Electrocardiogram (ECG/EKG) Allied Health II

Heart Sounds Primarily from blood turbulence caused by closing of the heart valves 4 heart sounds 1 st 2 are loud enough to be heard Auscultation – listening to sounds within the body

Lubb (S1) 1 st sound Louder and longer than the 2 nd sound Created by blood turbulence Associated with the closure of the AV valves soon after ventricular systole begins

Dupp (S2) 2 nd Sound Shorter and not as loud as the first Sound created by blood turbulence Associated with closure of the semilunar valves at the beginning of ventricular diastole

Heart Sounds (S3 and S4) Not normally loud enough to be heard S3 associated with rapid ventricular filling S4 associated with atrial contractions

Cycle (at rest) Lubb, dupp, pause, lubb, dupp, pause, lubb dupp, pause As heart rate increases, pause interval shortens

Electrical Activity SA Node – located in right atrium Natural pacemaker Begin each wave of muscle contraction in the heart Impulse in right atrium spreads over the muscles of both atria, causing them to contract simultaneously

Electrical Activity Atrioventricular Node Impulses from SA node travel to AV node Located on floor of right atrium, near septum AV node transmits impulses on to the bundle of His.

Electrical Activity Bundle of His Located in the interventricular septum Branches of the bundle of His carry electrical impulses to right and left ventricles and the Purkinje fibers Purkinje Fibers Stimulation of purkinje fibers causes ventricles to contract simutaneously, forcing blood into aorta and pulmonary arteries

Electrocardiogram (ECG or EKG) Recording of the electrical changes that accompany each cardiac cycle Composite of action potentials produced by all the heart muscle fibers during each heartbeat Electrocardiograph – instrument used to record the changes of an electrocardiogram

Electrocardiogram

P Wave First Small upward wave Represents atrial depolarization Spreads from SA node throughout both atria Atrial contraction

QRS Complex 2 nd wave Begins as downward deflection Continues as a large, upright, triangular wave Ends as downward wave Represents onset of ventricular depolarization Spread of wave through the ventricles Ventricular contraction

T Wave Signifies ventricular repolarization Relaxing & refilling of ventricles

How to Apply the Leads 10 Electrodes being placed Place limb leads 1 st V1 – Right sternal border, 4 th intercostal space V2 – Left sternal border, 4 th intercostal space V4 – 5 th intercostal space on left midclavicular line V3 – evenly placed between V2 and V4 V6 – left mid-axillary V5 – evenly spaced between V4 and V6

How to Apply the Leads

How to Calculate the HR 6-second strip method Count number of QRS complexes in 6 seconds and multiply by big blocks = 6 seconds Less accurate Go-to method for irregular rhythms Big block method Count the number of big blocks in between 2 QRS waves and divide into 300 More accurate There are 300 big blocks in 1 minute

EKG A normal EKG (regular beats at bpm) is called = Normal Sinus Rhythm (NSR) Sinus arrhythmia – rate increases with inhalation (common in children and some adults) Ventricular Fibrillation – Vfib, life threatening! No cardiac output, ventricles are fluttering. Lethal if not reversed in 3-5 mins

Possible Heart Rhythms

Artifact Interference seen on the monitor or rhythm strip May look like wandering or fuzzy baseline Can be caused by patient movement, poor electrode connection, improper grounding, faulty equipment

Artifact Some artifact can appear as lethal arrythmias Toothbrushing = V-Tach Tapping on electrode = V-Fib