Dysrhythmias Flashcards
Automaticity function
ability to generate electric impulses
Excitability fxn
can respond to outside impulses like chem, mech, elec
Conductivity fxn
receive electrical impulses and conduct it
Contractility fxn
myocardial cells shorten in response to impulse (pump)
How does cardiac conduction occur?
with action potentials!!
atrial depol
- contraction of atrium
- p wave
- atrial systole
ventricular depol
- ctx of vent
- QRS complex
- vent systole
- bundle of HIS and Purkinjean fibers tell them to get their squeeze on
cardiac repolarization
refilling the heart
ventricular repol
- t wave
SA node
in atria
- stimulates the P wave
AV node
- listens to SA
- gatekeeper
- tells vents to squeeze
- stimulates the QRS wave
Sinus rhythm
- normal conduction of the heart
- rate 60-100
- reg rhythm
- P wave upright and round, one before each QRS
- PR interval 0.12-0.2 seconds
- QRS under 0.12 seconds
Sinus arrhythmia
- another normal rhythm
- variability in HR
- no chx to CO
- HR 60-100
- PR 0.12-0.2
- narrow QRS
- common in younger ppl, assoc with respiratory or ANS fluctuations
Dysrythmias
any prob with impulse generation or conduction–abnormality of HR or CO, filling time
Causes of dysrhythmia
- inappropriate automaticity - cell initiates AP inappropriately in atrium
- triggered activity - extra impulse generated during or just after repol
- re-entry - cardiac cell or impulse in one part of the heart continues to depol after main impulse is done
What does “sinus” indicate
SA node prob
Sinus brady
- rate under 60 bpm
- normal rhythm
- normal PR int and QRS
- caused by hyperK, vagal response, digoxin tox, late hypoxia, olol, Ca block, amio, MI
- CM: dec CO, lightheaded, dizzy esp wit exert, syncope, chest pain, dyspnea, conduction, easy fatigue
- tx is atropine or pacemaker
What should you do before acting with sinus brady?
ASSESS FOR SX
Sinus tachy
- HR 100-150
- reg rhythm
- P waves similar (may be partial hidden)
- normal PR and QRS
- caused by catecholamines, fever, FVD (tachy is first), meds (beta, albuterol), coffee, nic, cocaine, EARLY hypoxia
- tx based on cause (fluids, antipyretics, analgesics, beta block if needed)
Paroxysmal supraventricular tachy (PSVT)
- occasional and fast
- above the ventricles
- 150-200 bpm
- usually no “p” wave or abnormal if present
- normal QRS
- usually r/t reentry of the AV node
- start, stop quick
- “heart racing”
- causes: overexert, stress, stims, dig tox, rheumatic CHD, CAD, WPW sx, R side HF
- s/s: palpits, chest pain, fatigue, dyspnea, lightheaded, dizzy
Premature atrial ctx (PACs)
- early p waves that look a little diff (morph chx)
- normal PR and QRS that follow P wave
- if freq–pt high risk for other dysrhythmia (usual afib)
- tx: check electros, may need O2 (hypoxia)
Atrial flutter
- originates in AV node and overrides SA node
- reentry impulse that is cyclic and repetitive
- atrial contraction at reg rhythm but quick rate >250
- vent rate slower (QRS) and narrow
- P wave classic sawtooth look
- 2:1, 3:1, 4:1
- caused by CHF, cardiomyo, valve disease, heart inflam, HTN, lung disease, electro, overactive thyroid, heart surg
A-fib
- irregular irregularity from lack of comm btwn atria and vent
- HR 100-175 or lower
- no identifiable P wave or even T
- fibrillation waves
- CM - racing, fatigue, dizzy, papits, dicomfort in chest, SOB, asymp
- caused by electro, hypoxia, CVD
What do you need to know about a-fib?
IF THE RATE IS CONTROLLED
a-FIB complications
HF, dec CO, embolus
- STROKE bc blood not pumped like it is meant to
a-fib tx
CONTROL RATE
- olol, CCB, digitalis
- prevent stroke - anticoag/plt
- ablation and cardioversion
Premature ventricular contractions (PVCs)
- ctx from ectopic focus in the vents
- early QRS, no p waves or normal rhythm, or negative QRS
- wide and distorted shape - QRS
- cause - electro, hypoxia, stims, fever, exercise, stress, CVD
- tx the cause
V tachy
- 3+ PVCs together
- ectopic focus in vents takes control and fires repeated - no atrial ctx occurs
- V dec CO
- assoc with MI, CAD, insignificant electro abnorm, HF, drug tox
- DEADLY RHYTHM
- 150-200 bpm, usual regularity
- no p-wave
- PR immeasurable
V tachy tx
- treat ACLS - depend on if palpable pulse
- pt v symptomatic unless converts back to other rhythm
- may need anti-dysrhythmic med like olol or CCB or electro replace
- if sustained v-tach, check pulse, CPR
First question to ask about V-tachy?
Pulse or pulse less?
V-fib
irregular waveform of varied shape and size
- vents quivering
- no effective ctx and NO CO
- CPR may be needed
