Final answer:
The two heart valves most frequently addressed in cardiac surgery are the mitral and aortic valves. The mitral valve connects the left atrium to the left ventricle and has two cusps, while the aortic valve is a semilunar valve that allows blood to flow from the left ventricle to the aorta.
Step-by-step explanation:
The two heart valves most commonly involved in cardiac surgery are the mitral and aortic valves. The mitral valve, also known as the bicuspid valve or the left atrioventricular valve, is located between the left atrium and left ventricle, and consists of two cusps. These are the anterior medial cusp and the posterior medial cusp, which are connected to the papillary muscles via the chordae tendineae. The aortic valve is one of the two semilunar valves, with the pulmonary valve being the other, and it allows blood to flow from the left ventricle into the aorta.
When considering the cardiac cycle and blood flow through the heart, after entering the right atrium from the vena cava, blood passes through the tricuspid valve to reach the right ventricle, then through the pulmonary semilunar valve to get to the lungs. After oxygenation, blood returns to the left atrium, flows through the mitral valve into the left ventricle, and is finally pumped through the aortic valve into the systemic circulation. Hence, the order of blood flow through these valves is tricuspid, pulmonary semilunar, mitral (bicuspid), and aortic semilunar.