Intravascular ultrasound (IVUS)
Intravascular ultrasound (IVUS) is more sensitive at reliably detecting subtle changes in the thickness of the intimal layer of the artery walls and provide measurements of artery lumen. Following transplantation, serial measurements are compared to the baseline. A greater than 0.5 mm increase in intimal thickness one year after transplantation is predictive of CAV changes on angiography within five years. The paradoxical reduction in the number of blood vessels, can also be detected by intravascular ultrasound.IVUS, however, tends to be used for research due to its drawbacks of being invasive, requiring the use of contrast material and cost. Dobutamine stress-echocardiography (DSE)
Alternatively, dobutamine stress echocardiography (DSE) is commonly performed and has an 85% sensitivity for the presence of CAV. A negative DSE correlates with a good prognosis.Other noninvasive diagnostics include positron emission tomography and computed tomographic angiography (CT angiography). In addition, ECGs may show atypical features of ischaemia. Biomarkers
Biomarkers for increased risk of CAV include C-reactive protein, serum brain natriuretic peptide and troponin I have been suggested. Classification
The degree of CAV after heart transplantation has been obtained from a variety of sources including The Cardiac Transplant Research Database, the ISHLT registry and The United Network for Organ Sharing registry.The International Society for Heart and Lung Transplantation (ISHLT) have formulated and standardized a terminology, based on diagnostic findings, to define the presence and severity of CAV, which in turn reflects prognosis. The severity of CAV is defined by the degree of narrowing of the coronary arteries and the presence of restrictive heart disease.
However, in CAV, histology specimens typically show concentric thickening of the intimal layer of the main coronary arteries on the surface of the heart and in intramyocardial arteries which can become obliterated within a few years. There is smooth muscle cell migration, foamy macrophages and lymphocytic infiltrates. This can be seen to affect the whole length of the coronary arteries and often the smaller arteries. Calcification does not always occur in CAV and if it does appear, it happens late. The compensatory arterial dilation does not occur in CAV. Unlike in nontransplanted people with coronary artery disease due to atherosclerosis, in CAV occlusion with thrombus of the vessel lumen is rare.Inflammation and endothelial injury can be triggered by the donor arrest, organ procurement, and allograft ischaemia and reperfusion. Diagnosis
As symptoms are so variable and often absent, diagnosis has been a challenge. Hence, regular follow-up and monitoring of the allograft for early signs of disease is advocated. Coronary angiography
Surveillance is performed by regularly repeating coronary angiography in the cardiac catheterization laboratory, the diagnostic test of choice. This is typically performed annually for the first five years after transplantation. Angiography in CAV characteristically demonstrates diffuse stenoses in large coronary arteries and a reduced number of smaller coronary arteries, also known as "peripheral pruning". However, because CAV frequently affects the entire length of the coronary artery, CAV may not be apparent by angiography alone.