The left and right ventricles compose the lower portion of the heart, and these chambers are responsible for pumping blood to the body. Blood from the right atrium passes into the right ventricle through the tricuspid valve. After the blood arrives in the right ventricle, contractions of the ventricles open the pulmonary valve, and blood is pumped into the main pulmonary artery. The heart's mitral valve transports blood from the left atrium to the left ventricle. When the ventricles contract, blood in the left ventricle enters the aortic valve and is pumped directly to the aorta. Oxygen-rich blood is carried by the aorta to the rest of the body. The walls of the ventricles are thicker than those of the atria because they need more power for contraction. The electrical impulses sent by the nodes in the atria are relayed to the ventricles through tissues known as Purkinje fibers, and this stimulates contraction. Ventricular fibrillation, ventricular tachycardia, and heart failure are some of the cardiac conditions that impact the ventricles.