Blood passes through tricuspid valve into right ventricle, then out through pulmonary artery to lungs. Bicuspid and tricuspid valves also called atrioventricular valves.
Cardiac muscle is autorhythmic .
In patients with too slow of impulse rate, normal rhythm is restored with an artificial pacemaker. Cardiac Reserve is the ratio between the maximum cardiac output a person can achieve and the cardiac output at rest. People with severe heart disease may have little or no cardiac reserve because damage to heart tissue limits the heart's ability to increase output per beat. This limits their ability to carry out simple daily tasks. Much of the normal volume of blood flow is shunted away from the lungs in favor of systemic circulation.