First Degree Atrioventricular Heart Block - prolonged PR interval-measures the time required for an impulse to travel from the SA to the AV node. PRI longer than 0.20
Second degree AV block Type I - progressive prolongation of PRI, gradual shortening of R to R intervals
P wave not followed...
First Degree Atrioventricular Heart Block - prolonged PR interval-measures the time required for an
impulse to travel from the SA to the AV node. PRI longer than 0.20
Second degree AV block Type I - progressive prolongation of PRI, gradual shortening of R to R intervals
P wave not followed by a QRS wave
a pause with an R to R interval less than the sum of two P to P intervals
first conducted atrial impulse after the pause shows a shorter or normal PRI
Second Degree AV Block Type 2 - Rhythm: ventricular irregular; atrial regular
Rate: atrial rate > ventricular rate
P waves: P waves may not be followed by QRS
PRI: WNL or prolonged ; PRI before and after a blocked P waves are constant.
QRS duration: WNL; greater than 0.11 sec block occurs below the bundle.
characteristics of first degree AV block - rhythm: regular
Rate: usually WNL
P waves: one positive before each QRS complex
PRI: prolonged
QRS: normal
causes of first degree AV block - - normal in hx of cardiac disease especially athletes
- Acute MI
- acute mydocarditis or endocarditis
,- cardiomyopathy
- degenerative fibrosis and sclarosis
- drugs
- hyperkalemia
- increased vagal tone
- ischemia or injury to the AV node or AV bundle
- rheumatic heart disease
- valvular heart disease
what causes second degree AV block type I - RCA, athletes, aortic valve disease, atrial septal defects,
meds, mitral valve prolapse, rheumatic heart disease.
what do i do about second degree AV block type I - atropine for bradycardia.
second degree AV block type II causes - MI is related to conduction effects, acute myocarditis, aortic
valve disease, cardiomyopathy, fibrosis of the conduction system, rheumatic heart disease
second degree AV block type II s/s - depends on the ventricular rate: if normal it is asymptomatic. could
progress to third degree, pacemakers, ECG, pulse ox, obtain VS, administed oxygen, est IV access
temporary or permanent pacing
third degree heart block - Rhythm: ventricular regular; atrial regular, no relationship is present
Rate: the atrial rate is greater than the ventricular and the ventricular rate is determined by the escape
P waves: normal in size and shape; not followed by a QRS complex
PRI: no PRI bc they are not related
,QRS: narrow or wide depending on the location of the pacemaker
hypokalemia T waves - depressed T waves
hyperkalemia T waves - elevated T waves
causes of third degree heart block - acute MI
acute myocarditis
congenital heart disease
drug effect
fibrosis of the conduction system
increased parasympathetic tone
capture - The successful conduction of an artificial pacemaker's impulse through the myocardium,
resulting in depolarization
demand pacemaker - Pacemaker that discharges only when the patient's heart rate drops below the
preset rate for the pacemaker; also known as a synchronous or noncompetitive pacemaker.
dual chamber pacemaker - Pacemaker that stimulates the atrium and ventricle; dual-chamber pacing is
also called physiologic pacing. They must get counseling because it hurts
Fixed rate pacemaker - Pacemaker that continuously discharges at a preset rate regardless of the
patient's intrinsic activity; also known as an asynchronous pacemaker
Sensitivity - the extent to which an artificial pacemaker recognizes intrinsic cardiac electrical activity.
Temporary Pacemaker's - transcutaneous: pads that go on the body
transvenous: introduced into a central vein like the subclavian, femoral, brachial, internal or external
jugular vein
, complications of pacemaker: - bleeding, infection, MI, PE, dysrhythmias, wires can come loose, battery
changes, no MRI, cannot do electromagnetic
for transcutaneous: hold pressure for 20 minutes and tell the patient not to bend their legs.
12 lead ECG - Limb leads: I, II, II, AVR, AVL, AVF
Chest leads: V₁ , V₂ , V₃ , V₄ , V₅ , V₆
Where are the 12 lead ECG's placed - Lead I: receives information from R and L arms; dipolar views top
of the heart
Lead II: receives information from R arm and L foot
lead III: receives information from Left leg and arm
avR: on the Right arm
avF: on the right foot
avL: on the Left arm
Normal Sinus Rhythm - rhythm: R-R and P-P intervals are regular
rate: 60-100 bpm
P waves: positive (upright) in lead II; one precedes each QRS complex, P waves look alike
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