Get to Know Your Heart

The heart has two upper chambers, the right atrium and left atrium, and two lower chambers, the right and left ventricles. The atria and ventricles work together to pump blood through the heart— but it’s your hearts electrical system that drives the process.


  • Two large veins, the superior and inferior vena cava, carry oxygen-depleted blood through the body and deliver it to the right atrium.
    At the same time, the pulmonary veins carry oxygen-rich blood from the lungs and deliver it to the left atrium.
  • The heart’s natural pacemaker, the sinoatrial (SA) node, fires electrical signals to both atria, causing them to contract and push blood to both ventricles.
  • The electrical impulses move through the atrioventricular node (AV) node and a pathway of fibers, causing both ventricles to contract and move blood from the heart to the rest of the body.
  • The SA node fires again and stimulates another heartbeat. This cycle repeats 60-100 times per minute.


  • When the heart’s in AFib, irregular electrical impulses disrupt the signal between the SA and AV node, and the heart beats irregularly.
  • The atria pump less blood into the ventricles.
  • Blood can pool in the heart and form clots.
  • Irregular heartbeats can strain the heart muscle over time and set the stage for heart failure.

Content adapted from and used with permission. Image is licensed for use.

*Originally published in The Beat – August 2019. Read the full newsletter here.

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