EKG Characteristics: Regular narrow-complex rhythm Rate 60-100
bpm Each QRS complex is proceeded by a P wave P wave is upright in
lead II & downgoing in lead aVR www.uptodate.com
ETIOLOGIES: Fever Hyperthyroidism Effective volume depletion
Anxiety Pheochromocytoma Sepsis Anemia Exposure to stimulants or
illicit drugs Hypotension and shock Pulmonary embolism Acute
coronary ischemia and myocardial infarction Heart failure Chronic
pulmonary disease Hypoxia
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Variations in the cycle lengths between p waves/ QRS complexes
Normal p waves, PR interval, normal, narrow QRS
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Usually respiratory--Increase in heart rate during inspiration
Exaggerated in children, young adults and athletesdecreases with
age Usually asymptomatic, no treatment or referral Can be
non-respiratory, often in normal or diseased heart, seen in
digitalis toxicity
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All result in bradycardia Sinus bradycardia (rate of ~43 bpm)
with a sinus pause Tachy-brady syndrome
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ETIOLOGY: Often due to sinus node fibrosis, Sinus Node arterial
atherosclerosis, inflammation (Rheumatic fever, amyloid, sarcoid)
Occurs in congenital and acquired heart disease and after surgery
Hypothyroidism, hypothermia Drugs: digitalis, lithium, cimetidine,
methyldopa, reserpine, clonidine, amiodarone Most patients are
elderly, may or may not have symptoms
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P wave is altered in shape compared to other P waves and comes
early. QRS complex normal shape and duration Cycle comes early
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Single ectopic beat that originates in the AV node or Bundle of
His area of the condunction system Retrograde P waves immediately
preceding the QRS Retrograde P waves immediately following the QRS
Absent P waves
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Digitalis toxicity Myocardial Infarction Myocardial Ischemia
Ingestion of caffeine or amphetamines
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Regular rhythm with P waves appearing at a rate of 250 to 300
beats/min P waves are noted for there saw tooth pattern, and or
flutter waves Can be in normal hearts or in those with disease Most
likely due to AV block, creating a reentry circuit
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In this rhythm the AV node is bombarded with impulses at a rate
of 300 + times per min. P waves are not distinguishable on the ECG,
and appear as fibrillation waves or f waves. QRS complexes are
irregular in rhythm with normal duration Causes mitral valve or
coronary artery disease, long standing hypertension is still the
most common cause
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Rate: 40 to 60 beats/minute (atrial and ventricular) Rhythm:
regular atrial and ventricular rhythm P wave: usually inverted, may
be upright; may precede, follow or be hidden in the QRS complex;
may be absent PR interval: not measurable or less than.20 sec QRS
and T wave : usually normal
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CAUSES Digitalis toxicity Inferior wall MI Myocardial Ischemia
Increased vagal tone Rheumatic heart disease Valvular disease
Organic disease of the SA node Verapamil toxicity
Anticholinesterase toxicity May occur immediately after
surgery
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Rate: 160 to 240 beats/minute Rhythm: regular atrial and
ventricular P wave: usually inverted, may be upright; may precede,
follow or be hidden in the QRS complex; may be absent PR interval:
not measurable or less than.12 sec QRS and T wave : usually
normal
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Supraventricular area fails to fire, which results in
ventricular ectopic beat Premature ventricular contraction (PVC)
most common. No visible P wave QRS > 0.12 seconds in length and
is bizarre in morphology
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Uniform Multiform PVC rhythm patterns Bigeminy PVC occurs every
other complex Couplets 2 PVCs in a row Trigeminy Two PVCs for every
three complexes
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Ventricular tachycardia (VTach) 3 or more PVCs in a row at a
rate of 120 to 200 beats/min Most likely due to acute infarction
and/ or ischemia Ventricular fibrillation (VFib) Preterminal event
in which myocardium is dying No visible P or QRS complexes. Waves
appear as fibrillating waves