Cardiac_ ECGs, anatomy and physio, conditions Flashcards
Right coronary artery
supplies blood to the right atrium and ventricle and part of the left ventricle
Left anterior descending artery
supplies blood to the anterior wall of the left ventricle, interventricular septum, right bundle branch, and left anterior fasciculus of the left bundle branch
Circumflex artery
supplies blood to the lateral walls of the left ventricle, left atrium, and left posterior fasciculus of the left bundle branch
Cardiac veins
collect blood from the capillaries of the myocardium
Coronary sinus
returns blood to the right atrium
Atrial kick
atrial contraction<br></br>contributes about 30% of the cardiac output
Cardiac output
the amount of blood the heart pumps in one minute<br></br>calculation: heart rate x stroke volume
Stroke volume
the amount of blood ejected with each ventricular contraction
Preload
the passive stretching exerted by blood on the ventricular muscle at the end of diastole
Afterload
the amount of pressure the left ventricle must work against to pump blood into the aorta
Contractility
the ability of the heart muscle cells to contract after depolarization
Sympathetic nervous system
increases heart rate, automaticity, AV conduction, and contractility<br></br>norepinephrine and epinephrine released
Parasympathetic nervous system
vagus nerve stimulation reduces heart rate and AV conduction<br></br>acetylcholine released
Automaticity
the cell’s ability to spontaneously initiate an impulse (pacemaker cells)
Excitability
how well a cell responds to an electrical stimulus
Conductivity
the ability of a cell to transmit an electrical impulse to another cardiac cell
Contractiltiy
how well the cell contracts after receiving a stimulus
Phase 0: rapid depolarization
cells receive an impulse from a nearby cell and is depolarized
Phase 1: Early Repolzarization
early rapid repolarization occurs
Phase 2: Plateau Phase
A period of slow repolarization occurs
Phase 3: Rapid Repolarization
The cell returns to its original state
Phase 4: Resting Phase
The cell rests and readies itself for another stimulus
SA Node firing rate
60-100 bpm
AV Junction firing rate
40-60 bpm
Purkinje Fibers firing rate
20-40 bpm
Retrograde Conduction
Impulses that are transmitted backward toward the atria
Monitor problem: artifact
May appear with excessive movement (wavy, bumpy, tremulous
Monitor problem: interference
Caused by electrical power leakage or from other equipment (thick, unreadable)
Monitor problem: wandering baseline
All waveforms may be present; can be caused by movement of the chest wall when breathing, poor electrode placement, or poor electrode contact
ST segment depression may indicate:
Myocardial ischemia or digoxin toxicity
ST segment elevation may indicate:
Myocardial injury
Tall, peaked, or tented T waves may indicate:
Myocardial injury or hyperkalemia
Prolonged QT interval increases the risk of…
Torsades de pointes
Short QT intervals may indicate:
Digoxin toxicity or hypercalcemia
Prominent U wave may indicate:
Hypercalcemia, hypokalemia, or digoxin toxicity
Characteristics of normal sinus rhythm
Normal rate
Regular rhythm
Uniform P wave before every uniform QRS complex
Normal PR and QT intervals
Normal T waves
Characteristics of sinus bradycardia
