Relative to aorta monitoring, the ACC/AHA Thoracic Aortic Disease Guidelines have a very informative summary of some of these issues (like us "old" folks above the age of 35 who are supposedly more radiation proof! :cool2: ):
"Selection of the most appropriate imaging study may depend on patient-related factors (ie, hemodynamic stability, renal function, contrast allergy) and institutional capabilities (ie, rapid availability of individual imaging modalities, state of the technology, and imaging specialist expertise). Consideration should be given to patients with borderline abnormal renal function (serum creatinine greater than 1.8 to 2.0 mg/dL)—specifically, the tradeoffs between the use of iodinated intravenous contrast for CT and the possibility of contrast-induced nephropathy, and gadolinium agents used with MR and the risk of nephrogenic systemic fibrosis. Radiation exposure should be minimized. The risk of radiation-induced malignancy is the greatest in neonates, children, and young adults. Generally, above the age of 30 to 35 years, the probability of radiation-induced malignancy decreases substantially. For patients who require repeated imaging to follow an aortic abnormality, MR may be preferred to CT. MR may require sedation due to longer examination times and tendency for claustrophobia. CT as opposed to echocardiography can best identify thoracic aortic disease, as well as other disease processes that can mimic aortic disease, including pulmonary embolism, pericardial disease, and hiatal hernia. After intervention or open surgery, CT is preferred to detect asymptomatic postprocedural leaks or pseudoaneurysms because of the presence of metallic closure devices and clips. We recommend that external aortic diameter be reported for CT or MR derived size measurements. This is important because lumen size may not accurately reflect the external aortic diameter in the setting of intraluminal clot, aortic wall inflammation, or AoD. A recent refinement in the CT measurement of aortic size examines the vessel size using a centerline of flow, which reduces the error of tangential measurement and allows true short-axis measurement of aortic diameter. In contrast to tomographic methods, echocardiography- derived sizes are reported as internal diameter size. In the ascending aorta, where mural thrombus in aneurysms is unusual, the discrepancy between the internal and external aortic diameters is less than it is in the descending or abdominal aorta, where mural thrombus is common."
My bicuspid aortic valve stenosis and ascending aorta aneurysm monitoring story is as follows: I had an echo done 35 times (one for each year of my life) prior to surgery. When the last echo measured part of my ascending aorta at 5.0 cm, a dramatic increase from years prior, a CT scan was ordered (which confirmed). A week later came the cardiac cath, followed 3 weeks later by my surgery, already scheduled before the cath. From now on, it will be yearly echo with periodic CT "as needed". Due to my shiny new pacemaker, MR is no longer an option, but so long as the radiation continues to suit me well :rolleyes2: , no problem and no real limitations from a cardio monitoring standpoint.
