From the Guidelines
The heart's electrical system regulates heartbeat through specialized cells that generate and conduct electrical impulses in a coordinated sequence, and when disrupted, various treatments are available depending on the specific condition, including medications, implantable devices, and catheter ablation, as described in the European Heart Journal 1. The sinoatrial (SA) node initiates each heartbeat by generating an electrical impulse that travels through the atria to the atrioventricular (AV) node, which briefly delays the signal before sending it through the bundle of His and Purkinje fibers to stimulate ventricular contraction. Some key points about the heart's electrical system include:
- The electrical activation then travels roughly twice as fast through the specialized cardiac conduction system, proceeding down the His-Purkinje system and right and left bundles, which activate both ventricles simultaneously starting at the endocardium and spreading to the epicardium 1.
- A properly timed atrial contraction can increase cardiac output by 25% to 30% 1.
- Abnormalities of the cardiac conduction system due to disease, aging, drugs, or pacing can adversely affect AV synchrony and synchronous LV contraction and relaxation, which may reduce functional aerobic capacity by altering LV systolic and diastolic function 1. When this system is disrupted, various treatments are available depending on the specific condition. Some treatment options include:
- Medications like beta-blockers (metoprolol, 25-100mg twice daily), calcium channel blockers (diltiazem, 120-360mg daily), or antiarrhythmics (amiodarone, 200mg daily after loading dose) may be prescribed for minor arrhythmias 1.
- More severe disruptions might require implantable devices such as pacemakers for slow rhythms or implantable cardioverter-defibrillators (ICDs) for dangerous fast rhythms 1.
- Catheter ablation, a procedure that destroys small areas of heart tissue causing abnormal rhythms, is effective for conditions like atrial fibrillation or supraventricular tachycardia 1.
- For patients with atrial fibrillation, anticoagulants like warfarin (target INR 2-3) or direct oral anticoagulants (apixaban 5mg twice daily) are often necessary to prevent stroke 1. These treatments work by either regulating the electrical impulses, replacing the heart's natural pacemaker function, or preventing dangerous consequences of electrical disruptions. It is essential to note that the choice of treatment depends on the underlying condition and the severity of the disruption, and should be guided by the most recent and highest quality evidence, such as the guidelines published in the European Heart Journal 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Overview of the Heart's Electrical System
The heart's electrical system is a complex network that regulates heartbeat, consisting of three main parts: the sinus node, the atrioventricular node, and the His-Purkinje system 2. This system is vital for the initiation and coordination of the heartbeat.
Key Components of the Electrical System
- The sinus node: responsible for generating the electrical impulse that triggers the heartbeat 3, 4
- The atrioventricular node: receives the impulse from the sinus node and transmits it to the ventricles 3, 5
- The His-Purkinje system: a network of specialized fibers that conduct the impulse to the ventricles, causing them to contract 2, 5
- The atrioventricular ring and outflow tract tissues: additional structures that play a role in the electrical system 2
Regulation of Heartbeat
The electrical system regulates heartbeat by generating and conducting electrical impulses that trigger muscle contractions in the heart 5. The system is controlled by a complex interplay of ion channels, intracellular Ca(2+)-handling proteins, and gap junction channels 2.
Disruptions to the Electrical System
Disruptions to the electrical system can cause arrhythmias, such as bradycardia, heart block, and bundle branch block 2. These disruptions can be caused by various factors, including fibrosis, remodelling of ion channels and related proteins, and naturally occurring mutations in ion channels 2.
Treatments for Disruptions
Treatments for disruptions to the electrical system include the use of specific heart rate-lowering drugs and biopacemaking 2. Additionally, understanding the mechanisms of dysfunction and the role of ion channels can help in the development of new therapeutic strategies 2.