Heart Anatomy and Rhythm

Heart Anatomy


One approach for understanding the anatomy of the heart is to follow the flow of blood through the cardiac cycle. The cardiac cycle is how blood gets transported through your heart and pumped into the arteries.

 

The superior and inferior vena cava are veins that lead into the right atrium (the top right chamber of your heart) transporting oxygen-poor blood that has circulated through your body to your heart. As oxygen-poor blood travels from the right atrium into the right ventricle, the tricuspid valve closes with a thud. The thud is the beat you hear with a stethoscope. Each set of valves is meant to ensure the directional flow of blood through the heart's chambers and into the arteries.

As the right ventricle contracts, blood is pumped into the pulmonary artery and the pulmonary valve shuts to ensure directional blood flow. The deoxygenated blood is transported to the lungs to become oxygenated and returns to the left atrium via the pulmonary veins.

As oxygen-rich blood flows from the left atrium into the left ventricle, the mitral valve closes to ensure directional blood flow. As the left ventricle contracts, oxygenated blood is pumped into the aorta to be transported through your body.

Heart Rhythm

Cardiac conduction is the cycle of electrical impulses which regulates the precise, coordinated rhythms of the atria and ventricles.

Atop the right atrium is a bundle of cells called the sinoatrial (SA) node. The SA node is often referred to as your heart's natural pacemaker because it controls the initiation of electrical impulses in cardiac conduction.

Once an electrical impulse is fired across the SA node, it travels across the right atrium to the left atrium causing the contraction in atrial systole.

The electrical impulse reconvenes at the atrioventricular (AV) node and travels across the atrioventricular bundle (Bundle of His) where it splits down the right and left crura spreading into the Purkinje fibers causing the contraction in ventricular systole. A cardiac arrhythmia occurs when erratic electrical impulses disrupt normal cardiac conduction which interferes with the cardiac cycle.

Atrial fibrillation (AF) is a unique but very common cardiac arrhythmia that affects approximately 5.1 million Americans.2 If you are concerned about the risks of atrial fibrillation, and you would like information about your current options for treatment, you can request our free information brochure about atrial fibrillation.