Report from SCCT: Cardiac CTA helps in pre- and postoperative setting

July 13, 2007

Cardiac CT angiography has become an important diagnostic tool for pre- and postoperative management of patients with cardiac disease, according to researchers reporting at the Society of Cardiovascular Computed Tomography meeting.

Cardiac CT angiography has become an important diagnostic tool for pre- and postoperative management of patients with cardiac disease, according to researchers reporting at the Society of Cardiovascular Computed Tomography meeting.

Dr. Marcus Y. Chen from the National Heart, Lung, and Blood Institute and colleagues from the University of Colorado Health Sciences Center in Denver found CTA to be an accurate noninvasive method to visualize and characterize atrial septal defect anatomy prior to percutaneous closure.

"The intrinsic 3D nature of CT provides better anatomic visualization than 2D ultrasound or fluoroscopic imaging techniques," Chen said.

He suggested that future applications of CTA assessment of atrial septal defects could significantly reduce radiation exposure time by helping physicians preselect appropriately sized devices and choose the best x-ray working views prior to percutaneous closure.

Reducing the amount of radiation exposure is important in this patient population, as many patients are younger than 50 and a majority are women. Atrial septal defects represent 10% of congenital heart diseases. Most of these are asymptomatic until adulthood, but significant complications such as right heart failure and atrial arrhythmias can arise if they remain untreated.

Chen and colleagues prospectively evaluated with a 40-slice scanner 23 consecutive patients scheduled for atrial septal defect closure and 23 matched controls. Intracardiac and/or transesophageal echocardiographic assessment was used as the reference.

CTA identified the defect size, location, and surrounding tissue rim in all 23 patients with defects, as well as those not identified in the 23 controls. The CTA size measurement correlated with ultrasound (R = 0.66, p = 0.001). CTA significantly underestimated size in three patients with thin or aneurysmal inter-atrial septums, however, due to the limited temporal and spatial resolution of the CT scanner, Chen said.

In another study, Dr. Mateen Akhtar and colleagues at The Cleveland Clinic found CTA valuable to preoperatively assess aortic root morphology in patients undergoing percutaneous aortic valve replacement.

Prior studies reported that aortic stenosis is associated with aortic root dilation. Given the small margin for error in positioning the replacement, as well as the possibility that the aortic root can be altered in the setting of aortic stenosis, preoperative assessment of the aortic root morphology is necessary to determine if the patient's anatomy is sufficient for deployment of the device, Akhtar said.

Using a dual-source scanner, researchers prospectively evaluated 50 consecutive patients, 25 with calcific aortic stenosis and 25 normal controls. They found that patients with stenosis have statistically significantly reduced distances from the annulus of the right or left coronary cusps to the respective coronary artery ostia.

"These findings have implications for design and deployment of percutaneous aortic valve replacement devices," Akhtar said.

Dr. Robert C. Gilkenson from the radiology department at the University Hospitals of Cleveland discussed the value of CTA as an effective surgical management tool for patients with aortic valve disease. At his institution, these patients often are older and have more complex and advanced disease. About 40% have had previous cardiac surgery.

The role of coronary CTA in these patients is multifactorial. One of the most important strategies is to use CTA to define the surgical perfusion/cannulation techniques.

"This has made a significant difference in the morbidity and mortality rates of our population," Gilkenson said.

Surgeons also want to know the nature of coronary artery involvement in aortic valve disease. Surgeons will use buttons of tissue around the coronary arteries to re-implant these patients after their root and ascending graft repair. If the aortic disease significantly involves these buttons of tissue, they are of no use to the surgeons.

Coronary artery involvement in postsurgical complications of aortic valve replacement is similarly important. Such involvement in postoperative perivalvular aneurysms/pseudoaneurysms is optimally imaged with CTA, Gilkenson said. In the patient evaluated for surgical replacement of the calcified aortic valve homograft, preoperative CT coronary angiography is important in the decision for coronary artery reimplantation versus bypass.