Cardiac Arryhythmias Flashcards
Cardiac Arrhythmias
They are deviations from normal cardiac rate and rhythm
causes of cardiac arrhythmias
damage to the heart’s conduction system or systemic causes such as electrolyte imbalance
fever, hypoxia, stress, infection or drug toxicity
_____________ reduce the efficiency of the heart’s pumping cycle
Dysrhythmias
Bradycardia
refers to a regular but slow heart rate (less than 60 beats/min). It often results from parasympathetic stimulation
Tachycardia
is a regular rapid heart rate (greater than 100-160 beats/min). This may be a normal response to sympathetic stimulation
Sick sinus syndrome
is a heart condition marked by alternating bradycardia and tachycardia, often requiring a mechanical pacemaker
____________________ are the most common dysrrhythmias
• Atrial conduction abnormalities
__________________________ are extra contractions of the atria
• Premature atrial contractions/beats (PAC/PAB)
cause of Premature atrial contractions/beats (PAC/PAB)
PACs occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat
Atrial Flutter
refers to atrial rate of 160-350 beats/min (less filling time so less output)
• Atrial Fibrillation
is a rate over 350 beats/min
____________ causes pooling of blood in the atria and is treated with anticoagulant medications to prevent clotting and stroke (no filling)
• Fibrillation
What causes heart blocks
• Atrioventricular node abnormalities cause heart blocks
AV conduction is prolonged.
There is a slight delay in getting the electrical signal from SA to AV node, but heart functions normally
It is recognized on the electrocardiogram by a prolonged P-R interval.
First degree heart block
First degree heart block
• A heart block in which the conduction of impulses through the atrioventricular node is delayed but all atrial beats are followed by ventricular beats.
Second degree heart block (Mobitz type I)
the PR intervals become progressively longer until a QRS complex is dropped every 2nd or 3rd or 4th beat
treatment for second degree heart block
Treatment is a cardiac pacemaker implantation
ventricular rhythm is irregular
Atrial rhythm is regular
Second degree AV block
Third Degree Heart Block
no impulse sent from the atria to the ventricles
The ventricles spontaneously contracts independent of the atria contraction (which is normal)
Third Degree Heart Block
Bundle branch block
interference with conduction in one of the bundle branches (right or left)
How does a Bundle branch block appear on the ECG
wide QRS wave
Ventricular tachycardia
a fast heart rhythm (greater than 100 beats/min), that originates in one of the ventricles of the heart
Ventricular fibrillation
muscle fibers contract independently and rapidly (uncoordinated quivering) and therefore are ineffective in ejecting blood
ventricular fibrillation causes what?
severe hypoxia in the myocardium and contraction ceases
Treatment of Cardiac Dysrhythmias
Antiarrhythmic drugs are effective in many cases. Atrial dysrhythmias often respond to digoxin
SA nodal problems or heart block problems requires a pacemaker
Serious life threatening dysrhythmias require defibrillators and other cardioversion devices (shocking the heart to interrupt the disorganized electrical activity and allow the SA node to take control and return the heart to sinus rhythm)
_______________ is an acute systemic inflammatory condition that appears to result from an abnormal immune reaction occurring a few weeks after an untreated group A beta-hemolytic Streptococcus
Rheumatic fever
When do we see rhuematic fever occur
in children 5-15y/o
Preceding Rheumatic fever, what is seen?
upper respiratory tract infection, tonsillitis, pharyngitis or strep throat
Preceding Rheumatic fever
Antibodies to the streptococcus organisms form as usual, then what happens
then react with connective tissue in the skin, joints, brain and heart causing inflammation
Acute Rheumatic Fever is often clinically diagnosed based on Jones Criteria, which include:
pancarditis migratory polyarthritis of large joints subcutaneous nodules erythema marginatum sydenham chorea (involuntary, purposeless movement)
In diagnosis rheumatic fever, what is the most common clinical finding?
is a migratory arthritis involving multiple joints
Pancarditis
during acute stage infection
Inflammation of the outer layer, may include effusion which impairs filling
Endocarditis
affects the valves of the heart. The mitral valve is the most commonly affected valve. Recurrent inflammation increase risk for infective endocarditis
Myocarditis
inflammation develops as localized lesions in the heart muscle, called Aschoff bodies, may interfere with condution
Other sites of inflammation in patients with rheumatic fever
Large joints esp knees, migratory pain, skin - non-pruritic rash known as erythema marginatum; Wrists, elbows, knees or ankles may have small, non-tender subcutaneous nodules usually on the extensor surfaces; • Involuntary jerking movements of the face, arms and legs are called Sydenham’s Chorea or Saint Vitus’ dance
What are some of the signs and symptoms of inflammation due to rheumatic fever
Fever; Arthralgia: Joint pain without swelling; Raised erythrocyte sedimentation rate or C reactive protein; Leukocytosis; ECG showing features of heart block, such as a prolonged PR interval; Previous episode of rheumatic fever or inactive heart disease
The diagnosis of rheumatic fever can be made when ________________________________ are present along with evidence of streptococcal infection
two of the major criteria, or one major criterion plus two minor criteria,
Treatment of rheumatic fever
long term antibacterial agents, prompt treatment of any future streptococcal infection, anti-inflammatory agent; When valve damage has occurred, prophylactic penicillin may be given prior to surgical intervention
