Arrhythmia
-a problem with SA, AV, Bundle of His, or Purkinje network
pacemaker impulse formation, contraction impulse conduction
Singular causes of arrythmia?
arteriosclerosis, coronary artery spasm, heart block, myocardial ischemia
Combination causes of arrhythmia?
arrhythmogenesis
-results from disorders of impulse formation, conduction, or both
tachycardia
-caused by anatomical/physiological block creating a circus movement
-electrical impulses travel around the heart in a unidirectional block.
Ca2+ overload
Delayed after potentials(DAD) are caused by
K+
Early after depolarization (EAD) is caused by
Impulse fractionation
-too much vagal tone
-impulse generation during diastole that hits the atrium
-result is asynchronous atrial stimulation and atrial fibrillation
normal
P wave precedes QRS complex with constant R-R intervals; no alterations in SA
no signal originates from pacemaker, development of ectopic pacemaker, oscillatory afterdepolarizations
What are causes of Impulse formation disorders?
parasympathetic control
Bradycardia is caused by severely depressed conduction due to ___________ of AV.
atropine
Bradycardia is relieved by _______
Late (DAD)
after resting membrane potential is reached, cells get a secondary impulse which may or may not be sufficient to reach threshold.
Early (EAD)
- characterized by phase 3 repolarization interruption
-Long Q-T interval
Enhanced or ectopic pacemaker activity
-increases phase 4 slope
- new pacemaker cells are controlling conduction
Re-entry
abnormal circuit from tissue damage
-leads to repetitive action such as: micro-reentry circuit- daughter impulses
-circus movement
Respiratory sinus arrhythmia
-gradual lengthening and shortening of R-R intervals caused by intrathoracic pressure changes due to respiration.
inspiration
________ will increase heart rate
expiration
_________will decrease heart rate
Sinus pause/arrest
-failure of SA node to fire caused by digitalis toxicity, stroke, MI, myocarditis, increased vagal tone, hyper or hypokalemia
Sinus tachycardia
- fast heart rate (<100bpm) caused by fever, blood loss, anxiety, sympathetic stimulation (epinephrine)
Sick sinus syndrome
-bradycardia-tachycardia syndrome; result of partial-total SA node destruction and SA/AV node junctional arrhythmias
Premature Atrial contraction
-occur before next expected SA node impulse that is transmitted to ventricle and back to SA node
atrial flutter
-heart rate 240-450 bpm
-caused by congenital heart defects
atrial fibrillation
-most chronic arrhythmia; rapid disorganized atrial activation and uncoordinated contraction of atria
Torsades de pointes
-twisting of the points
-polymorphic ventricular tachycardia that can lead to sudden cardiac death
Ventricular tachycardia
: 3-4 + ventricular extra systoles, including V-fib
- ectopic beats, EADs or DADs, or re-entry circuits
A
What kind of AV block is characterized by slowed conduction and prolonged P-R interval?
A. 1st degree
B. 2nd degree
C. 3rd degree
B
What kind of AV block is characterized by some supraventricular complexes not being conducted; dropped beats occur.
A. 1st degree
B. 2nd degree
C. 3rd degree
C
What kind of AV block is characterized by no supraventricular complexes, ventricle generates its own impulse; complete heart block
A. 1st degree
B. 2nd degree
C. 3rd degree
normal ekg
sinus tachycardia
sinus bradycardia
sinus arrhythmia
Respiratory sinus arrhythmia
sick sinus syndrome
