During Typical Atrial Flutter, which structure forms the electrical barrier?

During Typical Atrial Flutter, which structure forms the electrical barrier?

• A. Crista terminalis
• B. Fossa ovalis
• C. Interatrial septum
• D. Mitral annulus

Answer: (A)

During typical atrial flutter, the activation forms a macroreentrant circuit around the tricuspid annulus in the right atrium. The electrical barrier that shapes this loop is the crista terminalis, a prominent muscular ridge that separates the smooth posterior right atrial wall from the trabeculated anterior wall and blocks conduction across it. Because of this barrier, the impulse is forced to travel around the annulus via the cavotricuspid isthmus, creating the flutter circuit. The other structures (fossa ovalis, interatrial septum, and mitral annulus) are not the barriers responsible for the typical right atrial flutter circuit.

During typical atrial flutter, the activation forms a macroreentrant circuit around the tricuspid annulus in the right atrium. The electrical barrier that shapes this loop is the crista terminalis, a prominent muscular ridge that separates the smooth posterior right atrial wall from the trabeculated anterior wall and blocks conduction across it. Because of this barrier, the impulse is forced to travel around the annulus via the cavotricuspid isthmus, creating the flutter circuit. The other structures (fossa ovalis, interatrial septum, and mitral annulus) are not the barriers responsible for the typical right atrial flutter circuit.