Med Surge chapters 24, 25, and 26 Flashcards
Sinoatrial (SA) node
75 to 100 beats per minute
Atrioventricular (AV) node
40 to 60 beats per minute
Bundle of His
a continuation of the AV node
carries electrical signals from the AV node to the bundle branches.
Purkinje fibers
a diffuse network of conducting strands .
spread the wave of depolarization through the ventricles
purkinje fibers can act as the pacemaker with a rate between 20 and 40 beats/min (when SA and AV nodes fail)
Cardiac Cycle
One heartbeat
Electrical representation of contraction and relaxation of atria/ventricles
Electrocardiogram (ECG)
Shows cardiac electrical activity.
Isoelectric Line
Baseline
Seen with no electrical activity
Straight line produced
P wave
First wave
Represents atrial depolarization
P R interval
Beginning of P wave to beginning of Q R S complex
QRS complex
Follows P wave
Q wave first negative (downward) deflection
R wave first positive (upward) deflection
S wave second negative deflection
Q,R,S waves are not…
present every time.
this represents ventricular depolarization
T wave
Ventricular repolarization
Follows Q R S complex
Q to T interval
Beginning of Q wave to end of T wave
Varies based on gender, heart rate, age
Prolonged or shortened Q T interval can lead to ventricular arrhythmias
U wave
Rare
Indicates hypokalemia
After T wave
what is an Arrhythmia?
disturbance in the rhythm and conduction
Sinus Bradycardia
s/s and treatment
fatigue or fainting
None if asymptomatic
treatment:
Oxygen, atropine, dopamine or epinephrine, pacing
sinus tachycardia
s/s and treatment
Angina or dyspnea (Older adults are more sensitive)
Therapeutic interventions
Medications
Adenosine, beta blocker, calcium channel blocker
Atrial Arrhythmia
Premature atrial contractions (P A C’s)
Atrial flutter
Atrial fibrillation
Premature Atrial Contractions therapeutic interventions
Treat cause
Beta blocker
Atrial Flutter Signs and symptoms
if the ventricular rate normal
None
if a rapid ventricular rate is present then
Palpitations, angina, dyspnea
therapeutic interventions for atrial flutter
Cardioversion for rapid ventricular rate Rapid atrial pacing Calcium channel blocker Beta blocker Catheter ablation
Atrial Fibrillation
Signs and symptoms
Palpitations
Faint radial pulse
Atrial Fibrillation therapeutic interventions
Synchronized cardioversion if unstable Medications Beta blocker Calcium channel blocker Digoxin Anticoagulation Ablation (after anticoagulation) Surgical maze procedure
causes of Third-Degree Atrioventricular Block
Coronary heart disease
Myocardial infarction
Digoxin
Aging