electrical conduction in the heart
SA node → AV node → bundle of his → bundle branches → purkinje fibers
does electrical or mechanical conduction in the heart come first?
electrical
P wave
depolarization of atria
PR segment
depolarization of AV node to bundle of his
PR interval
depolarization of SA node to AV node
QRS complex
depolarization of ventricles; repolarization of atria
T wave
repolarization of ventricles
atrial kick
the amount of blood pushed into the ventricles by the atria at the end of atrial
depolarization
how much does atrial kick contribute to cardiac output?
up to 20%
which two conditions lead to a loss of atrial kick?
atrial fibrillation; ventricular pacing
arrhythmias
,abnormal cardiac rhythms caused by disorder of the formation or conduction of
the electrical impulse, or both
premature atrial complexes (PACs)
early electrical impulses beginning in the atria
most sustained (chronic) arrhythmia in the US
atrial fibrillation
atrial fibrillation
chaotic atrial rate that is prevented by the AV node; quivering atria
risk factors of atrial fibrillation
increased age; male gender; increased BMI; systolic BP ≥ 160; HTN; heart
murmur; heart failure
treatment of atrial fibrillation
medications (beta blockers, calcium channel blockers, class III antiarrhythmics);
cardioversion; treat cause (HF, MI)
biggest risk of atrial fibrillation
embolic stroke; atria are not fully contracting, so blood is pooling and is at risk
for clotting
sinus tachycardia
> 100 bpm, regular
causes of sinus tachycardia
physiologic (exercise); pathologic (fever, stress, pain)
treatment of sinus tachycardia
treat the cause
sinus bradycardia
< 60 bpm, regular
causes of sinus bradycardia
, physiologic (sleep); pathologic (hypotension, chest pain, AMS, HF)
treatment of sinus bradycardia
medication (atropine, dopamine, epinephrine); pacing
premature ventricular complexes (PVCs)
early electrical impulses beginning in the ventricles; retrograde conduction
unifocal PVCs
same shape and direction
multifocal PVCs
different shape and direction; more areas of the heart that are not functioning
properly
manifestations of PVCs
different apical and brachial HR; lightheadedness; dizziness; SOB; chest pain;
electrolyte abnormalities
treatment of PVCs
treat cause; antiarrhythmics
ventricular tachycardia
wide, fast, regular rhythm
causes of vtach
ischemia; previous MI; congenital heart disease; electrolyte abnormality (K +
Mg); acid-base abnormalities
treatment of stable vtach
treat cause; cardioversion; medication
treatment of unstable (pulseless) vtach
check pulse; CPR/defibrillation; treat cause
are stable and unstable vtach both medical emergencies?
yes
SA node → AV node → bundle of his → bundle branches → purkinje fibers
does electrical or mechanical conduction in the heart come first?
electrical
P wave
depolarization of atria
PR segment
depolarization of AV node to bundle of his
PR interval
depolarization of SA node to AV node
QRS complex
depolarization of ventricles; repolarization of atria
T wave
repolarization of ventricles
atrial kick
the amount of blood pushed into the ventricles by the atria at the end of atrial
depolarization
how much does atrial kick contribute to cardiac output?
up to 20%
which two conditions lead to a loss of atrial kick?
atrial fibrillation; ventricular pacing
arrhythmias
,abnormal cardiac rhythms caused by disorder of the formation or conduction of
the electrical impulse, or both
premature atrial complexes (PACs)
early electrical impulses beginning in the atria
most sustained (chronic) arrhythmia in the US
atrial fibrillation
atrial fibrillation
chaotic atrial rate that is prevented by the AV node; quivering atria
risk factors of atrial fibrillation
increased age; male gender; increased BMI; systolic BP ≥ 160; HTN; heart
murmur; heart failure
treatment of atrial fibrillation
medications (beta blockers, calcium channel blockers, class III antiarrhythmics);
cardioversion; treat cause (HF, MI)
biggest risk of atrial fibrillation
embolic stroke; atria are not fully contracting, so blood is pooling and is at risk
for clotting
sinus tachycardia
> 100 bpm, regular
causes of sinus tachycardia
physiologic (exercise); pathologic (fever, stress, pain)
treatment of sinus tachycardia
treat the cause
sinus bradycardia
< 60 bpm, regular
causes of sinus bradycardia
, physiologic (sleep); pathologic (hypotension, chest pain, AMS, HF)
treatment of sinus bradycardia
medication (atropine, dopamine, epinephrine); pacing
premature ventricular complexes (PVCs)
early electrical impulses beginning in the ventricles; retrograde conduction
unifocal PVCs
same shape and direction
multifocal PVCs
different shape and direction; more areas of the heart that are not functioning
properly
manifestations of PVCs
different apical and brachial HR; lightheadedness; dizziness; SOB; chest pain;
electrolyte abnormalities
treatment of PVCs
treat cause; antiarrhythmics
ventricular tachycardia
wide, fast, regular rhythm
causes of vtach
ischemia; previous MI; congenital heart disease; electrolyte abnormality (K +
Mg); acid-base abnormalities
treatment of stable vtach
treat cause; cardioversion; medication
treatment of unstable (pulseless) vtach
check pulse; CPR/defibrillation; treat cause
are stable and unstable vtach both medical emergencies?
yes
