To access the left atrium through the retrograde approach, the catheter must pass through the aortic valve followed by the ______.

To access the left atrium through the retrograde approach, the catheter must pass through the aortic valve followed by the ______.

• A. Mitral valve
• B. Tricuspid valve
• C. Pulmonary valve
• D. Aortic valve

Answer: (A)

In a retrograde approach to the left atrium, you enter via the arterial system and cross the aortic valve into the left ventricle. From there, you must pass through the mitral valve to reach the left atrium. The other valves listed don’t lie on this route: the tricuspid valve is on the right heart, the pulmonary valve sits between the right ventricle and pulmonary artery, and the aortic valve has already been crossed first. This LV-to-LA passage through the mitral valve is what enables access to the left atrium without a transseptal puncture.

In a retrograde approach to the left atrium, you enter via the arterial system and cross the aortic valve into the left ventricle. From there, you must pass through the mitral valve to reach the left atrium. The other valves listed don’t lie on this route: the tricuspid valve is on the right heart, the pulmonary valve sits between the right ventricle and pulmonary artery, and the aortic valve has already been crossed first. This LV-to-LA passage through the mitral valve is what enables access to the left atrium without a transseptal puncture.