Term
| What is an electrocardiogram? |
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Definition
| A recording of electrical potential changes at the skin surface that result from the depolarization and repolarization of heart muscle. |
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Term
| What are the depolarization waves? |
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Definition
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Term
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Definition
| P wave is caused by electrical potentials generated when the atria depolarize before atrial contraction begins. |
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Term
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Definition
The QRS complex is generatated when the ventricles depolarize prior to contractions
-The Q wave is the initial downward spike
-the R wave is an upward spike
-the S wave is a second downward spike |
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Term
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Definition
| The T wave is a repolarization wave that is caused by potentials generated as the ventricles recover from the state of depolarization. |
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Term
| ECG's do not show the electrical activity of the SA node, the AV node, the bundle of His, or the bundle branches, why is this? |
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Definition
| ECG's record electrical activity of large groups of atrial or ventricular cells, the forces generated by these other areas are too small to be detected. |
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Term
| What wave is not always present in an ECG reading and what does it represent? |
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Definition
| The U wave. and it is believe to represent the ends stages of ventricular repolarization, possibly of the purkinje network. |
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Term
| If depolarization is going towards the positive electrode, will the ECG record and upward or downward wave? |
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Definition
| If depolarization is towards the positive electrode, then the ECG will show an upward wave |
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Definition
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Definition
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Term
| What is shown on an ECG when electrical activity is not detected? |
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Definition
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Term
| What is a biphasic waveform? |
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Definition
| A biphasic waveform is recorded when wave form depolarization moves perpendicularyly to the positive electrode. A straight line may also be formed during this scenario |
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Term
| Trace the route of electrical conduction through the heart. |
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Definition
-Electrical impulse begins in the SA NODE
-It then travels through the ATRIA
-It is delayed in the atria then travels to the BUNDLE OF HIS
-It is then conducted to the RIGHT and LEFT BUNDLE BRANCHES
-the left bundle branch divides into PURKINJE FIBERS which stimulate contractions of myocardial cells |
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Term
| What does phase 0 of ht emonophasic action potential of ventricular muscles correspond to on an ECG? |
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Definition
| Phase 0 is rapid depolarization and corresponds to the QRS complex. |
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Term
| What does phase 2 correspond to on an ECG recording? |
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Definition
| Phase 2 corresponds to the ST segments and shows the early part of repolarization of the right and left ventricles. |
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Term
| What does the T wave correspond to on the monophasic action potential of ventricular muscle? |
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Definition
| The T wave corresponds to phase 3. |
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Term
| Which waves on an ECG show atrial contraction? Ventricular? |
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Definition
P wave occurs at the beginning of atrial contraction
QRS complex occurs at the beginning of ventricular contraction. |
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Term
| What part of an ECG shows ventricular ejection? |
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Definition
| The ST segment coincides with the plateau of ventricular action potential and rapid ventricular ejection |
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Term
| What does the T wave represent? |
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Definition
| The stage of repolarization of when the ventricles when ventricular fibers begin to relax. Therefore the T wave occurs slightly before the end of ventricular contraction. |
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Term
| Through what stages of the ECG does the ventricles contract? |
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Definition
| From the beginning of the Q wave, to the end of the T wave. |
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Term
| What is the normal time of a PR interval? |
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Definition
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Term
| What is normal time for the QRS interval? |
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Definition
| Less than or equal to .10 seconds |
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Term
| How long is the QT interval? |
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Definition
| Less than or equal to .44 sec |
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Term
| How might preexcitation syndrome or junctional rhythm syndrom be detected on an ECG? |
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Definition
| By decrease in the PR interval |
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Term
| What do hypercalcemia or tachycardia show up on an ECG as? |
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Definition
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Term
| What can lead to a longer PR interval? |
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Definition
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Term
| What can cause a longer QRS interval? |
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Definition
Bundle branch blocks
Ventricular extopic beat
toxic drug effect
severe hyperkalemia |
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Term
| What disorders can causes a longer QT interval? |
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Definition
-Hypocalcemia
-hypokalemia
-hypmagnesemia
-myocardial ischemia
-congenital prolongation of QT
-toxic drug effect (ex quinine) |
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Term
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Definition
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Definition
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Term
| Where are bipolar leads I placed? |
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Definition
Positive in left arm
Negative in right arm
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Term
| Where are bipolar II leads placed? |
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Definition
Right arm negative
Left leg positive |
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Term
| Where are bipolar leads III placed? |
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Definition
Left arm negative
Left leg positive
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Term
| What are the three augmented unipolar leads? |
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Definition
aVR-positive terminal on right arm
aVL-positive terminal on left arm
aVF-positive terminal on left leg |
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