JORGENSEN J1010, Руководство пользователя

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P Wave: the P wave is the first positive deflection and represents atrial depolarization. It normally
appears smoothly rounded and recedes each QRS complex at a specific interval.
P-R Interval: the P-R interval represents impulse conduction through the atria and into the AV node.
It extends from the beginning of the P wave to the onset of the Q wave.
QRS Complex: the QRS complex represents ventricular depolarization. It consists of three deflec-
tions. The Q-wave is the first negative deflection after the P wave. it results from the initial left-to-right
septal depolarization. the R wave is the first positive deflection after the P wave. The S wave is the
negative deflection following the R wave.
S-T Interval: the S-T segment extends from the end of the S wave to the beginning of the T wave.
T Wave: the T wave represents ventricular repolarization. Normally this wave is positive and symmet-
rical, but drugs, change in position, electrolyte imbalance, and food intake may alter the T wave.
Q-T Interval: the Q-T interval extends from the beginning of the QRS complex to the end of the T
wave. it represents ventricular depolarization and repolarization.
U Wave: the U wave is a small positive deflection after the T wave. It reflects repolarization of the
Purkinje fibers. This wave is not usually visible on the ECG.
Technical or mechanical problems that are superimposed on the normal P-QRS-T complexes are
known as artifacts. Other equipment in the area that uses electrical current may cause artifacts.
Muscle tremor or body movement may also cause artifacts, and efforts should be made to calm the
animal and make it comfortable. It is important to place the electrode clips correctly and hold the
limbs away from the body during right recumbent position to prevent the electrodes from moving with
the thoracic respiratory motions.
Indications for Electrocardiography
Electrocardiography is useful in clinical veterinary practice:
1. In the definitive diagnosis of cardiac arrythmias.
2. As an adjunct to determine cardiac enlargement (dilatation or hypertrophy)
3. As an indicator of certain electrolyte, acid-base, systemic, or metabolic disorders.
4. To individualize heart failure therapy.
The Abnormal Electrocardiogram
The first and most important step in ECG interpretation is differentiating between normal and abnor-
mal waveforms. The second step is differentiating between the various abnormal ECG patterns and
correlating them with known cardiac entities.
A Simple Checklist:
1. Are the P waves present?
a. If not, is there other evidence of atrial activity (fibrillatory waves)?
2. What is the relationship between atrial activity and QRS complexes?
a. What are the atrial and ventricular rates?
b. Is a P wave related to each QRS complex?
c. Does a P wave precede or follow the QRS complex?
d. Is the P-R and R-R interval constant?
3. Are the P waves and QRS complexes regular or irregular?
4. Are the QRS complexes wide or normal?
5. Is the ventricular rhythm regular or irregular?
6. Are there pauses or premature complexes that require explanation?
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