JORGENSEN J1010, Руководство пользователя

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ECG: One or more P waves are not followed by QRS-T complexes.
Complete Heart Block
Complete heart block occurs when AV conduction is absent and the ventricles are under the control
of pacemakers below the area of the block.
Clinical signs associated with complete heart block are syncope, sudden death, and congestive
heart failure.
ECG: The ventricular rate is slower than the atrial rate (more P waves than QRS complexes).
Figure 4-21 Complete heart block with an indioventricular escape rhythm (arrows) of 30 beats/min.
from a dog with syncope and severe ascites. A cardiac neoplasm was found at necropsy. (Tilley LP:
Essentials of Canine and Feline Electrocardiography. 2nd Ed. Lea & Febiger, Philadelphia, 1885.)
Arrythmias
An arrhythmia is an abnormality in the rate, regularity, or site of cardiac impulse and/or disturbance
of impulse conduction. during normal sinus rhythm, the cardiac impulse originates in the SA node
and spreads throughout the atria, AV node and His-Purkinje system, and ventricles.
Arrythmias Originating in the Sinus Node
Sinus Tachycardia
Sinus tachycardia is the most common arrhythmia in the dog and the cat. All ECG criteria are nor-
mal except that the heart rate is above 160 bpm in the dog and above 240 bpm in the cat.
Examples of physiologic conditions associated with sinus tachycardia include pain, fright, or excite-
ment. Pathological conditions include fever, shock, anemia, infection, congestive heart failure, hypox-
ia, and hyperthyroidism. Drugs that can cause sinus tachycardia include atropine, epinephrine, keta-
mine, and vasodilators.
Sinus Bradycardia
A regular sinus rhythm slower than the normal sinus heart rate is sinus bradycardia. Sinus bradycar-
dia can occur from severe systemic disease (e.g. renal failure), from toxicities, with dilated cardiomy-
opathy in the cat, or during end-stage heart failure.
Physiologic causes of sinus bradycardia include increased vagal tone due to carotid sinus pressure,
eyeball compression, or elevated intracranial pressure.
Drug induced causes include tranquilizers, digitalis, quinidine, morphine, and various anesthetic
agents.
ECG criteria are normal except that the heart rate is less than 70 bpm in the dog and less than 160
bpm in the cat.
Sinus Arrest
Sinus arrest is a failure of SA nodal impulse formation caused by depressed automaticity.
ECG: The rhythm can be regular or irregular with pauses demonstrating a lack of P-QRS-T complex-
es.
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