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44 Cards in this Set
- Front
- Back
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In a normal ECG, the P wave results from ____________, the QRS complex results from______ and the T wave results from____________
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depolarization of the atria
depolarization of the Ventricles REpolarization of the ventricles |
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What is a normal sinus rhythm in dogs?
Cats? |
60-160 bpm
120-240 bpm |
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What qualities will a normal sinus rhythm have?
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P waves positive
P-QRS compleses will be at regular intervals and of a consistant type and quality. |
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What qualities will VPC/PCV have? (ventricular premature complexes, Premature ventricular complexes)
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**WIDE BIZARRE QRS complexes w/o a P wave followed by a pause for VPC
*Ventricles are firing out of sequence *Cardiac impulses are originating in Purkinje fibers |
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What are some causes of VPC's?
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Cardiomyopathy, hyperthyroidism, aortic stenosis, valve disease, Cardiac neoplasia, hypoxia
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What are some concerns about VPC's?
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Will cause a pulse deficit, exercise intolerance, weakness, syncopy, sudden death
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What are some meds used to treat VPC;s?
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Anti-arrhythmic drugs such as Procainamide, Quinidine
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What qualities will an ECG showing Ventricular tachycardia have?
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**3 or MORE VPC's in a row
*wide bizarre QRS complexes, no relationship between P wave and QRS complexes P wave can come before, be hidden in or come after QRS -signifies SIGNIFICANT myocardial disease. -HR >150 bpm may be seen -can be intermittant or sustained -Potentially life threatening--can move into V-fib. |
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What are some causes of Ventricular tachycardia?
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Same as VPC's but to a more serious degree
Cardiomyopathy, hyperthyroidism, aortic stenosis, valve disease,, cardiac neoplasia. |
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Genetic terms
Pleiotropy |
1 gene has > 1 effect on an individual’s phenotype.
eg. pku |
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What defines a Sinus bradycardia on an ECG reading?
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*SINUS--->normal electrical activity
* Bradycardia-slow heart rate Normal P-QRS complexes, just at a slower rate |
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What is considered sinus bradycardia in dogs?
Cats? |
< 60 bpm
<120 bpm |
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What are some causes of sinus bradycardia?
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PHYSIOLOGIC: increased vagal tone due to vagus nerve stimulation from things such as intubation, vomiting, hypothermia. Transient occurence during Sx.
PATHOLOGIC: Renal failure, hyperkalemia, hypothermia, IMPENDING cardiac arrest DRUG INDUCED: Morphine, phenothiazines, anesthetics |
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How is sinus bradycardia typically treated?
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Rarely needed
Can give anti-cholinergics such as atropine and glycopyralate |
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What is a Sinus Arrhythmia?
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Alternating periods of slower/rapid HR associated with inspiration
**ECG will show Regularly irregular -fast parts same, slow parts same **inspiration causes vagal nerve stimulation , increase HR. Normal occurance in dogs. |
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What is ventricular asystole?
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**ABSENCE of ANY PAEMAKER activity.
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What are some ECG features for a Ventricular asystole reading?
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-no contractions of ventricles
-no cardiac output -no pulse no QRS complexes P waves may be present if animal has a complete AV block |
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What is the treatment for Ventricular asystole?
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CPCR
Meds: Epinephrine, Atropine, Tx primary cause of Asystole |
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What re some characteristics of Ventricular fibrillation?
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NO PULSE!! No Cardiac output!
-Ventricular depolarization w/o any coordinated activity -Rapid, CHAOTIC, irregular rhythms w/bizarre waves and oscillations -NO QRS complexes or P waves -Oscillations may be large/coarse or small/fine |
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What are some causes of of ventricular fibrillation?
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Hypoxia, shock, trauma, Hx of severe illness, cardiac disease, anesthesia reaction, hypothermia
electrolyte & acid-base imbalances |
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What is the standing treatment for ventricular depolarization?
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Defibrillation
--Goal is to stop fibrillation and stimulate heart to beat in a regular manner |
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What is an escape rhythm?
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SA node not firing, other nodes or fibers taking over. The further down the line the electrical stimulus starts, the slower the HR as a result.
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What is Atrial standstill?
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**ABSENCE of P waves and a regular escape rhythm. Nodes at other parts of the heart are taking over
-Regular but slower rhythm ,60bpm -No P waves, QRS may be normal or wide in a hyperkalemic Pt |
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What are some causes of Atrial standstill?
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Hyperkalemia
Atrial distension associated with cardiomyopathy Persistent atrial standstil |
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How is Atrial Standstill treated?
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Pacemaker for Persistent Atrial standstill
Hyperkalemia-calcium gluconate, dextrose, sodium bicarb, possibly insulin |
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What is Atrial Fibrillation?
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**LACK OF WELL DEFINED STRONG P WAVES
**CONSTANTLY IRREGULARLY IRREGULAR RR intervals -Caused by numerous disorganized Atrial impulses frequently bombarding the AV node --Rapid totally irregular atrial and venticular rate. Ventricular rate is irregular because the AV node only allows a limited # of impulses through. Atria-350-600 bpm & ventricular at 220-240 bpm |
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What is one of the major concerns about Atrial fibrillation?
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decreased cardiac output due to insufficient atrial contractions which leads to inadequate filling of ventricles.
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How is Atrial fibrillation treated?
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Tx underlying CHF
Meds: Digoxin-to reduce heart rate Propanolol-if further slowing is needed. |
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What is a First Degree Atrioventricular block?
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Delay in conduction of an impulse through the AV node
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What are some characteristics of a First Degree Atrioventricular Block?
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*PROLONGED P-R interval
HR Normal, normal intervals, Complexes normal, AV nodes hold beat too long |
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What are some causes of First Degree Atrioventricular Block?
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-older Pts secondary to degenerative changes in conduction system
-Potassium imbalances hypothyroidism Pt's can by asymptomatic and is NOT TREATED unless cause is identified. |
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What characterizes a Second degree Atrioventricular block?
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**1-2 P WAVES ARE NOT FOLLOWED BY QRS-T complexes.
-An intermittent failure or disturbance of AV conduction. |
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What are some of the items you will see on the ECG tape for a Second Degree Atrioventricular block?
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*P waves are normal and consistent
but ARE NOT followed by QRS-T complexes *P-R intervals often variable *May see progressive prolongation of P-R intervals until P is completely blocked *ventricular rate is slower that atrial due to occasional blocked P wave **Pt's typically asymptomatic, Tx underlying cause * can be a normal finding in horses |
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What is a Third degree Atrioventricular block?
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Cardiac impulse is completely blocked in the AV node
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What is the defining characteristic of an Third degree Atrioventricular block?
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**MULTIPLE missed QRS complexes
*no conduction between atia and ventricles. P waves have no constant relationship with the QRS complexes. |
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What are some items that will be noted on an ECG tape when there is a Third Degree Atrioventricular Block?
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**Multiple QRS complexes missed*P-P interval is normal
*QRS, when present, may be wide and bizarre or appear normal *Ventricular rate slower than atrial *Escape rhythm results as ventricles TRY to fire on their own |
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What are some causes of Third Degree Atrioventricular block?
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Congenital defect
Aortic stenosis Ventricular septal defect Cardiomyopathy, severe digitalis toxicity, endocarditis, myocardial infarction |
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How is Third degree Atrioventricular block typically treated?
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Pacemaker
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What is Sinus Tachycardia?
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**Most common arrhythmia in dogs and cats
*acceleration of SA node beyond its normal discharge rate resulting in increased HR *Rhythm is regular, with a possible slight variation in R-R interval P-R interval is constant. |
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What is considered Sinus Tachycardia in dogs?
Cats? |
HR >160 bpm
HR >240 bpm |
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What are some causes of Sinus tachycardia?
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PHYSIOLOGIC: Exercise, pain, STRESS, electric shock
PATHOLOGIC: Fever, hyperthyroidism, shock, Anemia, infection , CHF DRUGS: Atropine, glycopyrolate, epinephrine, vasodialators |
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Sinus tachycardia is treated by:
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ID'ing primary cause and treating that
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How does ventricular tachycardia differ from sinus tachycardia?
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Sinus Tach has regular rhythm with constant P-R intervals, possible Slight variation in R-R interval. NORMAL electrical conduction
Ventricular Tach-Wide bizarre QRS complexes with NO relationship between the P wave and the QRS comples |
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How does Ventricular Fibrillation differ from Atrial Fibrillation?
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V-Fib is characterized by rpaid, CHAOTIC irregular rhythms, no QRS complexes or P waves
A-Fib is characterized by a lack of well defined strong P waves. Complexes are irregularly irregular but are definable, unlike V-Fib |
