A pacemaker's principle revolves around sensing the heart's natural electrical activity and delivering electrical impulses only when the heart beats too slowly or irregularly. This ensures the heart maintains an adequate heart rate.
Here's a breakdown of the working principle:
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Sensing Natural Heartbeat: Pacemaker leads, equipped with electrodes, are implanted in the heart chambers (atria and/or ventricles). These electrodes continuously monitor the heart's intrinsic electrical activity.
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Rate Monitoring and Comparison: The pacemaker is programmed with a pre-set minimum heart rate. It constantly compares the sensed natural heart rate with this programmed rate.
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Pacing Impulse Delivery: If the heart rate falls below the programmed minimum, or if the heart misses beats, the pacemaker delivers precisely timed electrical impulses to stimulate the heart muscle. This artificial stimulation causes the heart to contract and beat at the desired rate.
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Demand Pacing (Most Common): Pacemakers primarily use "demand pacing." This means they only deliver electrical impulses when needed, allowing the heart to beat on its own when it can maintain an adequate rate.
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Response to Exercise/Activity: Some pacemakers are rate-responsive. They use sensors to detect bodily movement or breathing rate and increase the heart rate accordingly to meet the body's increased demand for oxygen during physical activity.
In essence, a pacemaker acts as a backup system, ensuring the heart beats reliably and at a sufficient rate to provide adequate blood flow to the body.
