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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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Arrhythmias arising in the ventricle (ventricular arrhythmias) are more likely to be found in people with more serious heart disease but may also be found in healthy individuals.

• Premature ventricular complex or PVC: This electrical impulse starts in the ventricle causing the heart to beat earlier than expected. Usually, the heart returns to its normal rhythm right away.
• Ventricular tachycardia: Fast and usually regular impulses come from the ventricles and cause a very rapid heart rate. This is usually a life-threatening tachycardia and needs immediate medical attention, possibly electrical shock or defibrillation that can stop or override these impulses.
• Ventricular fibrillation: Electrical impulses arise from the ventricles in a fast and disordered sequence. The resulting uncoordinated contractions cause the heart to quiver (appearing like a bag of worms) and lose the ability to beat and pump blood, leading to immediate cardiac arrest; electrical shock therapy may be life-saving.

Bradyarrhythmias produce heart rates that are too slow to allow enough blood to be pumped during either time of demand (stress or increased activity) or even during normal activity. Bradyarrhythmias are usually slower than 60 beats per minute. For example, patients may become dizzy and pass out when they try to stand up because not enough blood is pumped into the brain.

Arrhythmias can be frightening, but in many cases, especially in younger patients with normal underlying hearts, they are not life-threatening and can be effectively treated with medications.

• Supraventricular arrhythmias are very common in middle-aged and elderly adults. The older a person becomes, the more likely they are to experience an arrhythmia, especially atrial fibrillation.
• Many supraventricular arrhythmias are temporary and not serious, especially if no underlying heart disease is present. These arrhythmias can be a response to normal activities or emotions.
• Even if an arrhythmia has a serious underlying cause, the arrhythmia itself may not be dangerous. The underlying problem can often be treated effectively.

The purpose of this article is to give the reader an introduction to heart rhythm disorders. Each disorder or arrhythmia has been studied in great detail by many investigators so there are books and articles devoted to each type of arrhythmia. The reader is advised to click onto the references for more detail on each type of arrhythmia for more in depth details about diagnosis, treatments, and outcomes. Specific details for each type and subtype of disorder are far beyond the scope of this introductory article.

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