Cardio-Pathology-Dysrhythmia Flashcards
What are PVCs?
premature ventricular contractions
Tachycardia, bradycardia, irregular rhythm with normal contraction, ventricular fibrillation, no electrical activity (asystole) are all examples of:
dysrythmia
SA node damaged, other fibers or even the AV node can take over pacemaker function, slower intrinsic rate (causing bradycardia)
Sick sinus syndrome
Atrial myocytes become “irritable” and depolarize independently and sporadically (as occurs with atrial dilation), the signals are variably transmitted through the AV node, leading to the random “irregularly irregular” heart rate.
Atrial fibrillation
If the AV node is dysfunctional, varying degrees of occur.
• Heart block
simple prolongation of the P-R interval on electrocardiogram
(first-degree heart block
intermittent transmission of the signal to AV node
second-degree heart block
complete failure of signal to AV node
(third-degree heart block).
Dysrhythmia can be problems with nodes all the way to individual ?
myocytes
What are some possible causes of dysryhtmia?
– Ischemia – Hypoxia – Acidosis – Autonomic changes – Myocyte hypertrophy – Electrolyte imbalances – Genetic defects in ion channels – Drugs – Inflammation – Fibrosis and amyloid deposition
Abnormal pacemaker sites within the heart (abnormal automaticity), create abnormal conduction pathways and can cause cardiac dysrythmia
-no proper filling, output disrupted
Ectopic foci
What are reentry currents?
abnormal conduction of currents, can hit the AV node, can cause abnormal T and P waves
Alterations of SA or AV node, relatively uncommon, are alterations in rhythm.
sinus
- Premature atrial contractions (PAC)
- (Paroxysmal) Atrial tachycardia (approx. 100-150 bpm)
- Atrial flutter (150 bpm, atria pulsing 300)
- Atrial fibrillation – loss of coordinated contraction of atria (irregular ventricle contractions at 150-250 bpm)
are all examples of:
atrial dysrhythmias
(Paroxysmal) Atrial tachycardia can beat from:
approx. 100-150 bpm
combined TP waves, ORS complex can come right after one another
Atrial flutter can beat from:
150 bpm, atria pulsing 300
several P waves one after another
loss of coordinated contraction of atria (irregular ventricle contractions at 150-250 bpm) describes:
loss of synchrony
atrial fibrillation
T wave can be masked with atria going off on their own (ectopic foci)
random, not large P waves, occasional QRS
Why is there a risk for blood clots with atrial dysrhythmia’s?
inefficient pumping causes pooling and clotting of blood, which clots can be moved through circulation causing ischemia and/or infarcts
T and P waves overlapping a lttle, premature atrial contraction or complex (PAC)
loss of coordinated contraction of atria (irregular ventricle contractions at 150-250 bpm) describes:
loss of synchrony
T wave can be masked with atria going off on their own (ectopic foci)
random, not large P waves, occasional QRS
Atrial fibrillation
What is the difference between atrial flutter and atrial fibrillation?
atrial flutter has regular rate ventricular contraction (QRS), is less severe, and can progress to atrial fibrillation (irregular QRS)
What are the 3 treatments for atrial dysrhthmia?
- Node ablation
- Pacemaker installation
- Drugs
Which form of dysrhthmia is the most common?
ventricular premature beats or premature ventricular contractions (PVCs)
What is an excessive ventricular rate, but still beating in rhythm with atria?
Ventricular tachycardia -though still rhythmic, the atria may not be able to keep up and may not be getting enough blood
What is a complete loss of ventricular rhythm with a CO that falls to zero?
Ventriclar fibrillation
What effect do ventricular dysrhythmia’s have on C.O.?
➢ Depends upon the rate!!
➢ If too fast then not enough time for ventricles to fill and ↓ C.O.
Specific form of polymorphic ventricular tachycardia with a long QT interval • Congenital dysrhythmia caused by genetic polymorphism in K+ or Na+ channels. • Can also be caused by low K+ serum levels • May also be caused by drugs like Quinidine that slow myocardial repolarization
Torsades de pointes
What manifests as QT elongation followed by V. Tachycardia…..very dangerous • Risk of V. Fibrillation and sudden death! • Transient symptoms include dizziness and loss of consciousness..
Torsades de pointes (twisting around the point)
-you can notice that it gets bigger from the point of QT elongation on either side
What often occur due to ischemia in the Conduction Pathways • Generally do not cause dysrhythmia but can effect C.O.
Heart block
What type of heart block?
First degree AV Block (>200 ms PR interval)
-No treatment required
What type of heart block?
Second degree AV Block, Mobitz Type I or Wenckebach Lengthening of PR Interval until no QRS, often asymptomatic
What type of heart block?
Second degree AV Block, Mobitz Type II
Dropped beats not preceded by a change in the PR Interval
may proceed to third degree block
Often treated with pacemaker
What type of heart block?
3rd degree AV Block (complete)
Atria and ventricles beat independently of each other
P and QRS not together, rhythmically
Often treated with pacemaker
What disease can cause a 3rd degree AV heart block?
Lyme disease
What is happening?
Increasing P-Q interval with missing QRS
Mobitz type I, 2nd Degree Heart Block
What is driving the heart in a third degree heart block?
Bundle branch block
Cardiac Ouput can fall to zero
What can be caused by ischemic or structural changes in the conduction system or by intrinsic myocyte electrical instability?
Arrhythmias
In structurally normal hearts, are often due to mutations in ion channels that cause aberrant repolarization or depolarization.
arrhythmias
Sudden cardiac death results from and is most frequently a consequence of coronary artery disease (CAD).
ventriclar fibrillation
