Cardiology Flashcards
P wave
- Atria contracting
PR interval
- How much time it takes for electricity to travel to the ventricles
- Count boxes from beginning of p wave to beginning of QRS complex and multiply by .04 seconds
QRS duration
- How long it takes electricity to travel through ventricles
- QRS complex represents when the atria contracts
- Multiply boxes from end of PR interval to end of S wave by .04 seconds
T wave
Ventricles are repolarizing- getting ready to contract again.
Heart rate on an ECG
- Count boxes from R wave to R wave
2. For atrial rate, measure from P to P wave
ECG rhythm
Regular or irregular based on if sequence of waves occurs at a regular rate.
Sinus tachycardia
Heart rate is higher than 100 bpm
Sinus bradycardia
Heart rate is lower than 60 bpm
Electrical conduction system of the heart
- Passes through SA node in right atrium, causing the atria to contract
- Travels to AV node
- Travels down bundle of His to bundle branches
- Ventricles contract
AV bundle
On the septum separating the chambers
Purkinje Fibers
Fibers in ventricular walls
Sinus arrhythmia
- Intervals occur at irregular periods
2. Dizziness and palpitations
Premature atrial contraction
- Regularity of intervals are constant except for extra complexes
- Extra P waves will appear different from normal P waves
- Causes decreased cardiac output
Atrial flutter
- Very high atrial rate
- No P waves are present, “picket fence” flutter waves
- Decreased cardiac output
Atrial fibrillation
- P-P interval is unable to be determined due to fibrillatory waves, no visible P waves
- High atrial rate
- Irregular QRS duration
Premature ventricular contraction
- Early QRS complexes
2. No P waves for early complexes
Ventricular tachycardia
- No P waves, T waves in opposite direction
2. QRS complex has an irregular shape with a longer rate
Ventricular fibrillation
- P-P and R-R intervals are chaotic and can’t be identified
2. Only fibrillatory waves are present for QRS complex
Asystole
No electrical output
Shock
Failure of the circulatory system to adequately deliver oxygen to tissues.
Heart failure
- Inability to pump enough blood to sustain life
- Can be caused by valve disorders, cardiomyopathy, MI, or dysrythmia
- Treated by heart transplants or implants
- CHF can cause retention of fluid and congestion of blood in pulmonary circulation
- Usually begins on left side
Stroke volume
Blood ejected from the ventricles with each beat
Cardiac output
Volume pumped by one ventricle per minute.
