Term
| What does the EKG measure? |
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Definition
| A composite of all APs generated across the surface of the heart. |
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Term
| What does each grid box measure on the EKG? |
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Definition
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Term
| What is the maximum potential difference? |
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Definition
| When half of a tissue is depolarized |
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Term
| What is the baseline of the EKG |
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Definition
| Before the p wave, when there is no potential difference between tissues. |
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Term
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Definition
| Movement of charge across the atria. Expected to take 0.09 seconds. Deflects positive. |
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Term
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Definition
| The time it takes an impulse to start depolarizing the ventricles. Measured from P to Q, some people don't have Q. AV node is the major stopping point. |
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Term
| When do the atria repolarize? |
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Definition
| Under the QRS complex, not seen. Negative deflection. |
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Term
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Definition
| Ventricular depolarization. Q - movement across the septum. R - 50% of ventricle has been depolarized. S- Last part of ventricle, the left ventricular wall, depolarizes. All are a reflection of phase 0. |
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Term
| What does it mean when the QRS complex is widened? |
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Definition
| The impulse is slower reflecting a slowing in conduction. |
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Term
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Definition
| Measured from the S wave to the T wave, the amount of time it takes the ventricles to start depolarizing. Representative of phase 2. Prolong AP = Prolong ST = Prolong QT |
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Term
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Definition
| Repolarization of the ventricles, representative of phase 3. |
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Term
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Definition
| Measured from the Q wave to the end of the T wave. Depolarization and repolarization of the ventricles, takes ~0.44 sec. |
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Term
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Definition
| Rarely seen, Repolarization of the papillary muscle. |
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Term
| What are ways to see ischemia on the EKG? |
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Definition
| Depression of the ST segment, elevation of the S wave. |
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Term
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Definition
| Corrected for heart rate. A faster heart rate = shorter QT. |
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Term
| How does charge move across the heart? |
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Definition
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Term
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Definition
- Lead I - right arm to left arm
- Lead II - Right arm to left foot
- Lead III - Left arm to Left foot |
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Term
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Definition
| Voltage of Lead I + Voltage of Lead III = Voltage of Lead II. Avg direction of charge is toward Lead II. Can calculate a vector by having 2 leads. |
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Term
| What are the augmented limb leads? |
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Definition
Unipolar. One positive electrode, other attachments negative
aVR - positive lead on right hand
aVL - positive lead on left hand
aVF - positive lead on left foot |
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Term
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Definition
| From a depolarized area to a polarized area. Charge also moves from negative to positive. |
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Term
| If current moves toward a positive electrode, how does it deflect? |
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Definition
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Term
| If current moves toward a negative electrode, how does it deflect? |
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Definition
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Term
| If myocardial tissue increases in mass in the direction of deflection how does that impact deflection? |
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Definition
| The height of deflection increases. |
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Term
| What does the T wave vector of the atria look like? |
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Definition
| Inverted from the T wave of the ventricle, Up and to the left, |
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Term
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Definition
| Positioned around the surface of the heart, one is always positive starting with V1. If current moves away from + electrode, deflection is negative. So as + moves along the V leads, deflection gets more and more positive. |
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