A ventricular arrhythmia is a type of abnormal heart rhythm caused by malfunctioning electrical signals in the heart’s lower chambers, the ventricles. These arrhythmias can range from harmless to life-threatening emergencies. The severity depends on the specific type, its duration, and the person’s overall health.
Types of Ventricular Arrhythmias
Ventricular arrhythmias occur when electrical signaling in the ventricles is disrupted. These disruptions manifest in several distinct forms, each with different implications for heart function.
A common type is the premature ventricular contraction (PVC). A PVC is an extra heartbeat that originates in the ventricles and occurs sooner than the next expected normal heartbeat. This can feel like a skipped beat or a flutter, caused by the premature contraction followed by a pause and a more forceful subsequent beat. In otherwise healthy hearts, occasional PVCs are not considered dangerous.
Ventricular tachycardia (VT) is a more serious condition with a rapid heartbeat of over 100 beats per minute originating in the ventricles. This rapid rate prevents the ventricles from filling completely, reducing the amount of blood pumped to the body. VT can be non-sustained, lasting only a few seconds, or sustained, which persists for longer periods. Sustained VT can deteriorate into a more chaotic rhythm.
Ventricular fibrillation (V-fib) is the most dangerous type and a medical emergency. During V-fib, the ventricles quiver chaotically instead of contracting strongly, which is ineffective at pumping blood. This event, known as sudden cardiac arrest, causes loss of consciousness within minutes and can be fatal without immediate intervention. A specific form of VT known as Torsades de Pointes can also lead to V-fib.
Associated Symptoms and Underlying Causes
Common symptoms are related to the heart’s decreased ability to pump blood effectively. These include:
- Palpitations, felt as a fluttering, pounding, or skipped beats.
- Dizziness, lightheadedness, or syncope (fainting) as blood supply to the brain diminishes.
- Shortness of breath, as the lungs do not receive adequate blood flow.
- Chest pain, similar to angina, as the heart muscle is deprived of oxygen.
In the case of ventricular fibrillation, a person collapses suddenly.
The causes are often linked to pre-existing heart conditions or other systemic issues. Structural heart disease is a primary contributor; scar tissue from a previous heart attack or cardiomyopathy can interfere with the heart’s electrical pathways. Congenital heart defects present from birth may also create a predisposition for these rhythm disturbances.
Other factors can provoke ventricular arrhythmias. An imbalance of electrolytes, such as low potassium or magnesium, is a known trigger as these minerals are needed for proper electrical signaling in heart cells. Certain inherited genetic conditions, like Long QT syndrome or Brugada syndrome, directly affect the heart’s ion channels and increase risk. Some prescription medications and recreational drugs, such as cocaine, can also lead to these dangerous heart rhythms.
Diagnostic Procedures
To identify a ventricular arrhythmia, physicians use tests that record the heart’s electrical activity. The primary tool is the electrocardiogram (ECG or EKG). This test uses chest electrodes to capture electrical signals, allowing doctors to see the arrhythmia’s pattern if it occurs during the test.
Since arrhythmias can be intermittent, continuous monitoring is often necessary. A Holter monitor is a portable device worn for 24 to 48 hours to record every heartbeat. For less frequent arrhythmias, an event recorder can be used, which is activated by the patient during symptoms to capture the heart’s electrical activity at that moment.
A stress test may be used if an arrhythmia is triggered by physical activity to observe the heart’s response to exertion. The patient exercises on a treadmill or stationary bike while connected to an ECG to see if exertion provokes an abnormal rhythm.
For a more detailed analysis, an electrophysiology (EP) study may be recommended. This invasive procedure is performed in a hospital, where catheters are threaded through a blood vessel to the heart. These catheters record electrical signals from within, allowing doctors to map the arrhythmia’s origin and determine the most effective treatment.
Management and Treatment Approaches
Managing ventricular arrhythmias depends on the arrhythmia type, its frequency, and the patient’s overall health. Treatment goals include controlling the heart rate, preventing future episodes, and reducing the risk of sudden cardiac arrest. Management often begins with lifestyle changes and medication to address contributing factors.
Lifestyle modifications include avoiding triggers like excessive caffeine, alcohol, and certain drugs. Medications help control the heart’s rhythm and rate. Beta-blockers are prescribed to slow the heart rate, while other antiarrhythmic drugs can suppress abnormal electrical signals in the ventricles. Managing underlying conditions like high blood pressure or heart failure is also part of the treatment plan.
For those at high risk of life-threatening arrhythmias, an implantable cardioverter-defibrillator (ICD) may be necessary. An ICD is a small device implanted in the chest that continuously monitors the heart’s rhythm. If it detects a dangerous arrhythmia, it delivers an electrical shock to restore a normal heartbeat.
Catheter ablation is a more definitive treatment for some ventricular arrhythmias and is often guided by an EP study. During this procedure, a catheter delivers energy (heat or cold) to the small area of heart tissue causing the arrhythmia. This energy creates a scar that blocks the abnormal electrical pathway, often curing the arrhythmia.