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16 Cards in this Set
- Front
- Back
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What is depolarization?
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It is an electrical event that can be recorded on the EKG strip.
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What is involved in the process of depolarization
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The positive ions(mainly potassium) move from inside the cell to an area of less concentration outside the cell. The loss of positively charged ions causes the inside of the myocardial cell to become more negative. Once the cell is stimulated, the cell membrane allows sodium to rush from the extracellular space to the intracellular space. This results in sudden change in electrical charge within the cell that can be recorded on the ECG as indicated by the P wave and QRS complex.
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What is a biphasic waveform?
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It is a two phase waveform that goes up and down, occurs when the flow of energy is first directed toward a positive electrode and then toward a negative electrode.
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What does it mean, if a P wave changes in shape?
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It may indicate that the impulse was initiated somewhere else in the atria or possibly in the junctional tissue, but out of the SA node.
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What does it mean if a P wave is upside down?
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It is considered inverted. In lead two they indicate that conduction through the atria occurred in an opposite backward manner.
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What is the PR segment
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It is an isoelectric line that occurs from the end of the P wave to the beginning of the QRS complex.
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What does the PR interval represent?
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Atrial depolarization and AV delay. It is measured from the beginning of the P wave to the end of the PR segment.
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The QRS complex represents ventricular depolarization. TRUE/FALSE
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TRUE.
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What is the Q wave?
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It is the first negative deflection in the QRS complex.
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What is the R wave?
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It is the first positive deflection after the P wave.
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What is the S wave?
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This is also a negative wave. It can be small, tall or not exist.
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What is the ST segment?
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This is a line that follows the QRS complex. It represents part of ventricular repolarization process, and under normal circumstances should be isoelectric.
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What is the T wave?
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It follows the QRS wave and represents ventricular repolarization.
Changes in T wave amplitude occur with electrolyte imbalances or ischemic processes to the myocardium. |
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What is relative refractory period?
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There is atime during the resting state of the ventricle(ventricular repolarization when the T wave occurs) when the cardiac cell is regaining a negative charge.
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What is a U wave?
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It is a small waveform of unknown origen that may follow the T wave. They may be associated with T wave imbalances, especially hypokalemia.
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What is torsade de pointes?
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Certain antidysrhythmic drugs that prolong ventricular repolarization result in lengthened QT intervals. It is a polymorphic ventricular tachycardia. Treatment for this, is aimed at shortening the refractory period by interventions such as overdrive pacing or I?V isoproteronol, phenytoin or lidocaine. Magnesium has also shown beneficial results in terminating torsade de pointes.
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