• Cardiac dysrhythmias refers to any disturbance or abnormality in the cardiac conduction system causing an alteration in cardiac rate or rhythm.
• Normal conduction goes from the Sinoatrial (SA) Node S Atrioventricular (AV) Node S bundle of His S bundle branches S Purkinje fibers.
• Dysrhythmias may be benign or lethal.
• The terms “arrhythmia” and “dysrhythmia” are used interchangeably.
• Normal ECG interpretation:
—Heart rate is 60–100 bpm.
—Rhythm is regular.
—P wave is present and there is one in front of every QRS.
—PR interval is 0.12–0.20 seconds.
—QRS is 0.06–0.10 seconds.
Etiology: There are two major categories of dysrhythmias:
• Alteration in impulse formation
—Rate: tachycardia (over 100 bpm) or bradycardia (under 60 bpm)
—Rhythm: regular or irregular
—Ectopic: impulse starts outside the SA node, may be in the atria, junction, or ventricles
• Alteration in conductivity
—Reentry phenomena: activation of the muscle twice for one impluse
Precipitating factors: Ischemia, electrolyte disturbances, fever, acidosis, stress, exercise, pain, hypoxia, anemia, hypovolemia, cardiac and systemic diseases, atherosclerosis, medications, trauma, metabolic disorders, caffeine, alcohol, and aging.
Signs and Symptoms:
• May be asymptomatic
• Dizziness, angina, disorientation, hypotension, syncope, palpitations, diaphoresis, fatigue, shortness of breath, changes in pulse rate or rhythm
• Lethal dysrhythmias may progress to absence of pulse, heart sounds, blood pressure, and consciousness. Pupils can become dilated and cyanosis and seizures can develop leading to death
Diagnosis: 12-lead ECG, continuous ECG monitoring, intermittent ECG recording, stress test, electrophysiology studies, history and physical examination. Diagnostic studies to help determine cause of dysrhythmias may include blood chemistry, chest X-ray, and echocardiogram
Treatment: Depends on the dysrhythmia