Anatomical Basis for the Cardiac Interventional Electrophysiologist

Figure 7

(a, b) Spatial relationship of the left atrial structures. Posterosuperior view of volume rendered CT angiographies is shown. The left atrium is located in superior and posterior aspect of the heart. (a) Normal arrangement of the pulmonary veins (in red) is shown. The left atrial appendage (LAA) is shown in yellow. (b) Again shown are normal pulmonary veins. A supernumerary pulmonary vein (yellow arrows) is shown arising from the superior wall of the left atrium. The supernumerary pulmonary vein usually drains a portion of the right upper lung and inserts directly into the left atrium body or at the junction of the right superior pulmonary vein (RS) and the left atrium. (c) Longitudinal section through the left atrium and left ventricle, showing the smooth endocardial aspect of the left atrium. The black arrows indicate the crescentic edge of the oval fossa valve. (d) Longitudinal section through the pulmonary venous component showing the orifices of the right pulmonary veins. Note the close relation of the right veins orifices with the atrial septum (white arrows). (e) Short-axis section across the atrial chambers to show the atrioventricular valves, the vestibule of the left atrium (dotted line), and the nonuniform thickness of the left atrial wall. (f) Endocardial visualization of the left posterolateral wall showing a prominent left lateral ridge and extra pectinate muscle trabeculations (arrows) extending inferiorly from the appendage to the vestibule of the mitral valve. Double-headed black broken line is showing the left atrial isthmus. CS = coronary sinus, ICV = inferior cava vein, LA = left atrium, LAA = left atrial appendage, LI = left inferior pulmonary vein, LS = left superior pulmonary vein, MV = mitral valve, OF = oval fossa, RPA = right pulmonary artery, RI = right inferior pulmonary vein, RS = right superior pulmonary vein, and TV = tricuspid valve.

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