Anatomy of Atrial and Ventricular Septal Defects

Imaging of patent foramen ovale with 64-section multidetector CT

PURPOSE

To investigate the feasibility of 64-section multidetector computed tomography (CT) by using CT angiography (a) to demonstrate anatomic detail of the interatrial septum pertinent to the patent foramen ovale (PFO), and (b) to visually detect left-to-right PFO shunts and compare these findings in patients who also underwent transesophageal echocardiography (TEE).

MATERIALS AND METHODS

In this institutional review board-approved HIPAA-compliant study, electrocardiographically gated coronary CT angiograms in 264 patients (159 men, 105 women; mean age, 60 years) were reviewed for PFO morphologic features. The length and diameter of the opening of the PFO tunnel, presence of atrial septal aneurysm (ASA), and PFO shunts were evaluated. A left-to-right shunt was assigned a grade according to length of contrast agent jet (grade 1, <or=1 cm; grade 2, >1 cm to 2 cm; grade 3, >2 cm). In addition, 23 patients who underwent both modalities were compared (Student t test and linear regression analysis). A difference with P < .05 was significant.

RESULTS

A flap valve, seen in 101 (38.3%) patients, was patent at the entry into the right atrium (PFO) in 62 patients (61.4% of patients with flap valve, 23.5% of total patients). A left-to-right shunt was detected in 44 (16.7% of total) patients (grade 1, 61.4%; grade 2, 34.1%; grade 3, 4.5%). No shunt was seen in patients without a flap valve. Mean length of PFO tunnel was 7.1 mm in 44 patients with a shunt and 12.1 mm in 57 patients with a flap valve without a shunt (P < .0001). In patients with a tunnel length of 6 mm or shorter, 92.6% of the shunts were seen. ASA was seen in 11 (4.2%) patients; of these patients, a shunt was seen in seven (63.6%). In 23 patients who underwent CT angiography and TEE, both modalities showed a PFO shunt in seven.

CONCLUSION

Multidetector CT provides detailed anatomic information about size, morphologic features, and shunt grade of the PFO. Shorter tunnel length and septal aneurysms are frequently associated with left-to-right shunts in patients with PFO.

Perimembranous and muscular ventricular septal defects--morphology revisited in the era of device closure

Transcatheter closure of ventricular septal defects has advanced rapidly with improvements in device designs. We review the morphology of ventricular septal defects in heart specimens for a closer look at the shapes, sizes, and proximity to important structures. The three main types of defects, perimembranous, muscular, doubly committed and juxta-arterial, all have variable morphologies within each group. Oval rather than round shapes are more common. The shapes of muscular defects, in particular, can change from one side of the septum to the other. Perimembranous defects are close to the aortic and tricuspid valves and adjacent to the atrioventricular conduction bundle. Ventricular septal defects are three-dimensional and require careful assessment of proximity to important structures in their vicinity when assessing suitability for interventional closure.