Cardiology overview imaging
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Cardiology Overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Angiography
- Assess coronary lumen, not wall of artery
- Inaccurate and variable in the assessment of short, diffusely diseased left main lesions
- Provides less functional information than fractional flow reserve
- Should be combined with fractional flow reserve in intermediate lesions. PCI should be performed if FFR is < 0.80. It is safe to hold off on PCI in intermediate lesions with an FFR > 0.80 as shown in the FAME study.
CT Scanning
- CT scanning is not recommended as a screening tool in the asymptomatic patient
- A negative CT scan in a patient with a low pre test probability of disease has a high negative predictive value (>90%) in excluding the presence of CAD
- CT of stented patients can be difficult to interpret due ot bloassoming artifact
- CT is useful in the assessment of sapehanous vein graft patency
Echocardiography
- The E/E* ratio is a new criteria to assess diastolic dysfunction. E is the mitral inflow velocity, and E* is the tissue velocity.
- Echocardiography tends to overestimate that gradient in aortic stenosis
MRI
- Useful in the differentiation of myocarditis (subepicardial pattern) from myocardial infarction (subendocardial pattern)
- Useful in the assessment of pericardial thickening in the assessment of contstrictive pericarditis
- Useful in the assessment of myocardium in the assessment of fibrosis in hypertrophic obstructive cardiomyopathy (HOCM)
- Useful in the assessment of hemochromatosis and to follow magnitude of iron overload
Distinguishing Stunning from Hibernation and Chronic Myocardial Infarction
Stunning
- In the patient with stunning there is preservation of augmentation of contractility with an inotrope, glucose metabolism, and perfusion.
Chronic MI
- In the patient with a chronic MI and scar there is no augmentation with an inotrope, glucose metabolism (FDG uptake) is reduced, and there is reduced perfusion (reduced N labeled amonia).
Hibernating Myocardium
- In the patient with hibernating myocardium there is preserved augmentation of contractility within inotrope, there is preserved glucose metabolism, but there is reduced perfusion. This is often what is seen prior to coronary artery bypass grafting.