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Harrison's Principles of Internal Medicine, 18e
| Part 10. Disorders of the Cardiovascular System > Section 3. Disorders of Rhythm > |
Chapter 233. The Tachyarrhythmias
Sections: The Tachyarrhythmias: Introduction, Supraventricular Tachyarrhythmias, Ventricular Tachyarrhythmias, Further Readings.
Topics Discussed: arrhythmias; tachycardia.
Excerpt:"The term tachyarrhythmias typically refers to nonsustained and sustained forms of tachycardia originating from myocardial foci or reentrant circuits. The standard definition of tachycardia is a rhythm that produces a ventricular rate >100 beats per minute. This definition has some limitations in that atrial rates can exceed 100 beats per minute despite a slow ventricular rate. Furthermore, ventricular rates may exceed the baseline sinus rate and be <100 beats per minute but still represent an important "tachycardia" response, as is observed with accelerated ventricular rhythms. Premature complexes (depolarizations) are considered under the category of tachyarrhythmias because they may cause arrhythmia-related symptoms and/or serve as triggering events for more sustained forms of tachycardia.Tachyarrhythmias classically produce symptoms of palpitations or racing of the pulse. With premature beats, skipping of the pulse or a pause may be experienced, and patients may even sense slowing of the heart rate or dizziness. A more dramatic irregularity of the pulse is experienced with chaotic rapid rhythms or tachyarrhythmias that originate in the atrium and conduct variably to the ventricles. With rapid tachyarrhythmias, hemodynamic compromise can occur, as can dizziness..."
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