Week 4 Ekg Analysis, Cardiac Cycle, Event Timing Flashcards
What does the P wave represent?
The P wave represents atrial depolarization that leads to an atrial contraction
What does the qrs complex represent
Ventricular depolarization leading to ventricular contraction
What does T wave represent?
T wave represents ventricular repolarization
What are the 2 phases of the cardiac cycle
Systole and diastole
What node creates the P wave on ekg
Sinoatrial node
What is the duration of the PR interval
- From the onset of the p wave to the onset of the Q/R wave
- Normal duration is < 200 msec
What does the PR interval reflect
- Depolarization of the atria through the internodal pathways and buchmann’s bundle
- the spread of the impulse through the av node, av bundle, r and l branches, and purkinje fibers
What is the duration of the QRS complex
- onset of Q wave to end of S wave
- Normal qrs duration is < 110 msec
What is the ST segment
- early part of ventricular repolarization
- isoelectric unless disease is present
What is the QT interval
- onset of Q wave to end of T wave
- reflects ventricular systole
- normal time is 250-460 msec
What is the ekg timing for ventricular systole
R wave (closure of AV valves) to the end of the T wave (closure of SL valves)
What are the 3 phase of ventricular systole
1) isovolumic contraction time
2) rapid ejection of blood
3) reduced ejection of blood
When does isovolumic contraction time occur
- begins at AV valve closure
- ends at SL valve opening
What happens during ivct
- Ventricular volume is at its largest
- ventricular pressures rise rapidly in preparation for the SL valve opening
What happens during rapid ejection of ventricular systole
- rapid ejection of blood
- ventricular pressure rise rapidly while volume drops rapidly
What happens during reduced ejection
- ventricular pressure rapidly decreases
What is the ekg timing for ventricular diastole
From the end of the T wave (closure of SL valves) to the R wave (closure of AV valves
What are the 4 phases of ventricular diastole
1) isovolumic relaxation timing
2) early rapid filling of the ventricles
3) diastasis
4) late filling
When does ivrt occur
Begins at SL valve closure and ends when AV valves open
What occurs during ivrt
- heart volume is at its smallest
- volume remains the same because all valves are closed
- pressure decreases rapidly in preparation for av valve opening
