Cardiac Rhythm Disturbances (Atrial, Junctional, Ventricular) Flashcards
MAT (multifocal atrial tachycardia) is seen most commonly in people who have what condition?
-Chronic Lung Disease
Cor pulmonale is
-Right heart failure due to lung disease
People with Brugadda syndrome are prone to
- Sudden death from V-fib or V-tach
- Usually Middle eastern/Asian descent
- Collapses suddenly
WPW
- congenital
- HR 280-300
- from the presence of an accessory bypass tract
Principles
- Treat the patient–not the ECG
- Establish urgency of treatment–responsiveness, ABCD survey differential diagnosis, treat reversible causes (hypoxia, hypokalemia, hypovolemia)
- Access hemodynamic stability (LOC, BP, HR)
- Antiarrhythmic/electrical therapy
Arrhythmias symptoms
- Palpitations–skips, pounds, irregular
- Lightheadedness-faint like
- Syncope (near syncope)
- Chest pain
- Dyspnea
- Sudden death
Etiology
- Stress
- Ischemia (CAD), MI, HF
- Hypoxia, PE, COPD
- Metabolic acidosis
- Infection–Endocarditis, RF
- Inflammation–myocarditis, pericarditis
- Cardiomyopathy/alcohol; chemotherapy
- Electrolytic imbalance (low K, Mg, Ca)
- Drugs–caffeine, nicotine, thyroid, aminophylline, OTC
- Hypertension
Sinus Tachycardia causes
- Physiologic/pathologic process
- Need to look for cause!! :
- Emotion, anxiety, fear, drugs, hyperthyroid
- Fever, pregnancy, anemia, CHF
- Hypovolemia
- Treat underlying cause!
Sinus node
- Normally, the dominant cardiac pacemaker because of its intrinsic discharge rate is the highest of all potential cardiac pacemakers
- Bradycardia <60 beats/min
Medical conditions/situations associated with bradycardia
- Normal people
- Healthy athlete–well trained, good physical endurance
- Physiologic component to sleep, fright, carotid sinus massage, carotid hypersensitivity, avoid tight collars, shave neck lightly, massage or ocular pressure (glaucoma), mental control–yoga training
- Obstructive jaundice–effect of bile salts on SAN
- Sliding hiatal hernia
- Valsalva maneuver–lifting heavy objects, straining bowels
Other diseases associated with bradycardia
- Diseases of atrium or SAN–CAD:
- Inflammation
- Invasive neoplasm
- Cardiomyopathy
- Muscular dystrophy
- Amyloidosis
Drugs associated with bradycardia
- Digitalis, quinidine, hyperkalemia
- Drugs used for hypertension–mech to inhibit sympathetic tone (clonidine, methyldopa, reserpine)
- Beta blockers–propranolol, metoprolol
Acute inferior MI commonly present with
BRADYCARDIA!!
More conditions associated with bradycardia
- Acute inferior MI
- Ischemia
- decreased oxygen
- increased carbon dioxide
- decreased pH
- increased BP
- SSS (Sick sinus syndrome)–tach alternating with brady–older pt, vascular disease, advanced heart disease; Tx=pacemaker to control slow and meds to tx fast
- Convalescence from dig toxicity
Causes of bradycardia
- Sinus bradycardia
- Non conducted atrial bigeminy
- Sino atrial block
- AV block-incomplete/complete: sinus rhythm with 2:1 AV block, sinus tach with 3:1 AV block, sinus rhythm or tach with complete block; atrial flutter with complete block; A fib with complete block
Sinus arrhythmia
- SAN forms impulses irregularly
- waxes/wanes with phases of respiration
- HR increase with inspiration
- HR decreases with expiration
- sinus arrhythmia is a normal finding
EKG of sinus bradycardia
- P wave represents formation of sinus impulses
- Each atrial impulse is followed by a ventricular beat
- Rate less than 60/min
- P wave of sinus origin (normal axis)
- constant and normal PR interval (0.12-0.20)
- Constant P wave configuration in each lead
- regular or slightly irregular P-P cycle or R-R cycle
Most common cause of an unexplained pause in ECG is
-nonconducted premature atrial contraction (nonconducted PAC)
Sick sinus syndrome characteristics
tach alternating with brady–older pt, vascular disease, advanced heart disease
- S arrest
- SA block–>slow junctional rhythm
SSS seen in? Symptoms? Tx?
- ischemic, sclerotic, inflammatory changes in SAN
- may cause syncope, dizziness, fatigue, heart failure
- Tx with pacemaker for bradycardia and meds for tachycardia
Treatment for sinus bradycardia
- Depends on clinical setting/Dx the cause–may not need to be treated
- Depends on hemodynamics/impaired
- Depends on circulation
- Maybe no or few symptoms–No Rx
In sinus bradycardia, if hemodynamically compromised, may get combination of:
- low BP
- Low CO, los SV, low renal perfusion–oliguria
- SOB, low cerebral perfusion–confusion
- CP, cool, clammy, diaphoretic
- syncope, dizziness
- Fatigue
Commonly see Sinus bradycardia in
- Acute inferior MI, especially in 1st few hours (secondary to heightened vagal tone)
- This is related to SN ischemia or to a vagal reflex initiated in the ischemic area
- RX–if HR<45-50 with hemodynamic compromise/unstable acute situations
Drug used to treat sinus bradycardia
- Atropine–0.3–>0.5–>2mg IV
- Repeat 10 min
- Can also use epinephrine 2-10 ug/min, isoproterenol 1mg in 500 cc D5W 1-4 ug/min IV, pacemaker
Use caution in using atropine in patients with
-glaucoma–can increase Intraocular pressure
SE of atropine:
- Urinary retention
- Abdominal distension
- Transient
What is automaticity?
-Property of a cardiac cell to depolarize spontaneously during phase 4 of action potential/ leads to generation of an impulse
Atrial arrhythmias are caused by and seen in
- Premature atrial contraction (PAC) also APC
- seen in absence of significant heart disease; associated with stress, alcohol, tobacco, coffee, COPD and CAD
Premature beats
- an irritable focus spontaneously fires a single stimulus
- Premature atrial beat
- Premature junctional beat
- Premature ventricular beat
PAB does what to SA node
- resets SA node pacing
- SA node resets in step with premature atrial beat
Treatment of PACs
- If symptomatic:
- reverse causes
- Beta adrenergic antagonist (BB)
- Metoprolol 25-50mg BID-TID
Paroxysmal Atrial Tachycardia (PAT)
- Sudden heart rate greater than 100
- Rate 150-250/min
- Identify “irritable focus”; P’ wave
