Heart Rhythm Disorders (cont.)
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
In this Article
- What is an abnormal heart rhythm (arrhythmia)?
- How does the heart work?
- What causes heart rhythm disorders?
- What are the different types of heart rhythm disorders?
- What are the signs and symptoms of heart rhythm disorders?
- Atrial fibrillation (A-fib)
- Atrial flutter
- Sinus bradycardia
- Sinus tachycardia
- Ventricular fibrillation (V-fib)
- Ventricular tachycardia (V-tach)
- Premature atrial contractions (PACs) and premature ventricular contractions (PVCs)
- Paroxysmal supraventricular tachycardia (PSVT)
- Wolff-Parkinson-White (WPW) syndrome
- Heart blocks
- When to seek medical care
- How are heart rhythm disorders diagnosed?
- What is the treatment for heart rhythm disorders?
- What is the prognosis for heart rhythm disorders?
- Can heart rhythm disorders be prevented?
- Find a local Cardiologist in your town
What causes heart rhythm disorders?
Heart rhythm disturbances may occur because of problems within the heart itself or be the result of abnormalities in the body's environment that can affect the heart's ability to conduct electricity.
Cardiac or heart muscle cells become irritated when they are depleted of oxygen. This can occur during a heart attack, in which the coronary arteries, the blood vessels that supply the heart with blood, are blocked. Lack of oxygen can occur when the lungs are unable to extract oxygen from the air. Significant anemia, or low red blood cell count, decreases the oxygen-carrying capacity of the blood and may prevent adequate oxygen delivery. Rapid heart rates may be due to "wiring" problems with the electrical pathways in the heart. This can cause "short circuits" making the heart speed up and beat 150 beats a minute or more. The abnormality can be due to a physical extra electrical pathway such as that seen in Wolff-Parkinson-White (WPW) syndrome, or it can be due to changes in the electrical physiology between a few cells, like in atrial flutter.
Rapid heart rates can also occur because of environmental issues that affect the heart. These can be intrinsic to the body, like anemia, abnormal electrolyte levels, or abnormal thyroid hormone levels. They may also be due to reactions to outside influences like caffeine, alcohol, over-the-counter cold remedies, or stimulants such as amphetamines. To the cardiac muscle cell, they all appear to be adrenaline-like substances that can cause cell irritation.
Slow dysrhythmias can also be problematic. If the heart beats too slowly, the body may not be able to maintain an adequate blood pressure and supply the body's organs with enough oxygen-rich blood to function.
Slow heart rates may be due to aging of the SA node and its inability to generate an electrical pacemaker signal. Often though, it is due to the side effects of medications used to control high blood pressure. Side effects of beta blocker and certain calcium channel blocker drugs include a slowing of the heart rate.
Body environment is also important with slow heart rhythm abnormalities. Hypothermia, or low body temperature, is a potential cause.
What are the different types of heart rhythm disorders?
Heart rhythm disorders are classified according to where they occur in the heart and how they affect the heartbeat.
What are the signs and symptoms of heart rhythm disorders?
Many people may have heart rhythm disturbances and never be aware of them. Premature atrial contractions (PACs) and premature ventricular contractions (PVCs) are variations of normal and most often, people are unaware that an extra beat has occurred. However, some patients are keenly aware of any extra heartbeat, even if it is a normal variant and requires no treatment.
That said, the initial symptom of dysrhythmia is often palpitations, a sensation that the heart is beating too quickly, too slowly, beating irregularly, or skipping a beat. The palpitations may be intermittent or may require medical intervention to resolve.
Because of the heart rhythm abnormality, other symptoms may occur because of decreased cardiac output (the amount of blood that the heart pushes out to meet the body's demand for oxygen and energy). The patient may complain of lightheadedness, weakness, nausea and vomiting, chest pain, and shortness of breath.
In critical situations, the patient may fall to the ground or lose consciousness. This may be due to life-threatening dysrhythmias like ventricular fibrillation or ventricular tachycardia. It may be due to heart rates so fast that there isn't enough blood pressure generated to supply the brain with what it needs. The same result can also occur if the heart beats too slowly and insufficient blood pressure is generated.
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