Arrhythmias - Supraventricular
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Atrial Flutter
Description:
Rapid, regular P waves give ECG "sawtooth" appearance.
Atria beat ~300 beats/minute. Only ½ - 1/3 of the electrical impulses make it through the AV node and reach the ventricles, so heart rate is increased ~150 beats per minute.
Symptoms & Signs:
May be none. Or, may cause palpitations, and reduced CO, difficulty breathing, weakness, chest discomfort, syncope.
Treatment:
Rate control with drugs: beta-blockers, calcium channel blockers (verapamil, diltiazem). Rhythm control with cardioversion, drugs (antiarrhythmics), possibly ablation. Anticoagulants (warfarin) are used to prevent thromboembolism).
Risk Factors:
Commonly occurs in healthy people, but risk increases with other cardiac conditions, binge alcohol consumption, diabetes.
Clinical Concerns:
When coupled with other cardiac complications, can lead to stroke, makes heart work more difficult, ventricular weakening, and coagulation is more likely. Patients may have periods of atrial fibrillation.
Atrial Fibrillation
Description:
Rapid, irregular and indiscrete P waves on ECG. Atria do not contract in coordinated fashion, but send fast and irregular signals to ventricles increase heart rate.
Symptoms & Signs:
May be asymptomatic. Or, may experience lack of energy, fast, irregular pulse, difficulty breathing, palpitations, chest discomfort, dizziness.
Treatment:
Rate control with beta blockers and nondihydropyridine calcium channel blockers. AV node blockers possible (but rule out Wolff-Parkinson-White Syndrome with accessory pathway; look for wide QRS). Anticoagulation before cardioversion therapy to prevent thromboembolism.
Risk Factors:
Other cardiac problems, hyperthyroidism, obesity, diabetes, lung disease, binge alcohol consumption.
Clinical Concerns:
Stroke, systemic emboli. Echocardiography to check for structural defects, thyroid function tests. Must rule out Wolff-Parkinson-White Syndrome before prescribing AV-node blocking drugs, which are fatal to affected individuals.
Asystole
Often described as "Flat-lining" on ECG.
Cessation of electrical and mechanical cardiac activity, associated with decompensation of ventricular fibrillation.
Pulseless Electrical Activity
Cardiac electrical activity is present, but no pulse is present due to inactivity of cardiac muscle.
Both asystole and pulseless electrical activity can lead to cardiac arrest.
Premature Beats (Atrial & Ventricular)
Description:
Early atrial or ventricular contractions, visible on ECG. Caused by ectopic pacemaker activity.
Symptoms & Signs:
Palpitations, "skipped" beats.
Treatments:
Asymptomatic, if no other problems. Beware of antiarrhythmias, which can cause more serious arrhythmias.
Risk Factors:
Stress, caffeine, alcohol, hypoxia, electrolyte imbalances. Heart disease, pulmonary disease, and scarring can also interfere with normal electrical activity.
Clinical Concerns:
Can develop flutter/fibrillation.
Wolff-Parkinson-White Syndrome
Description:
Short PR interval and positive delta wave at beginning of broad QRS complex; delta wave reflects early depolarization. Occurs as result of AV node bypass, called bundle of Kent.
Symptoms & Signs:
May be asymptomatic. May have episodes of increased heart rate, chest pain, dizziness, palpitations, difficulty breathing.
Treatments:
Direct-current cardioversion therapy is preferred; long term treatment may require catheter ablation. Beware digoxin/nondihydropyridine calcium channel blockers to WPW patients, as they may trigger ventricular fibrillation (fatal).
Risk Factors:
Congenital form (mutation on Chromosome 7), or acquired.
Clinical Concerns:
Associated with Ebstein anomaly, displaced tricuspid valve). Atrial fibrillation can develop (depends on presence of antegrade conduction through accessory connection).