Cardiac rhythmicity

Cardiac rhythmicity refers to the inherent rhythmic nature of the heart's electrical and mechanical activities. This rhythmicity is crucial for the heart's primary function, which is to pump blood throughout the body. The heart's rhythm is regulated by a complex system of electrical signals and feedback mechanisms.

Overview

The heart's rhythm, or cardiac cycle, is a repeating cycle of contraction (systole) and relaxation (diastole) that occurs with each heartbeat. This cycle is regulated by the sinoatrial node (SA node), often referred to as the heart's natural pacemaker. The SA node generates electrical impulses that travel through the heart muscle, causing it to contract and pump blood.

Mechanism

The SA node generates an electrical impulse that travels through the atria, causing them to contract and pump blood into the ventricles. This impulse then reaches the atrioventricular node (AV node), which acts as a gatekeeper, delaying the signal before it travels down the bundle of His and into the Purkinje fibers. This delay allows the ventricles to fill with blood before they contract.

The electrical impulses generated by the SA node are influenced by signals from the autonomic nervous system. The sympathetic nervous system increases heart rate and contractility, while the parasympathetic nervous system decreases them.

Disorders

Disruptions in cardiac rhythmicity can lead to various arrhythmias, which are abnormal heart rhythms. These can range from harmless to life-threatening. Some common types of arrhythmias include atrial fibrillation, ventricular tachycardia, and heart block.

Treatment

Treatment for arrhythmias depends on the type and severity of the arrhythmia. Some arrhythmias can be managed with medication, while others may require procedures such as cardioversion, ablation, or the implantation of a pacemaker or implantable cardioverter-defibrillator (ICD).

See also

• Electrocardiogram
• Cardiac cycle
• Heart rate
• Heart

References

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