Which of the following tests is definitive in diagnosing aortic stenosis?

In the diagnosis of aortic stenosis, cardiac catheterization is considered a definitive test for several reasons. This invasive procedure allows for the direct measurement of the pressure gradient across the aortic valve, which provides quantitative data about the severity of the stenosis. During cardiac catheterization, the blood flow dynamics can be assessed in real-time, allowing clinicians to determine not only the presence of aortic stenosis but also its severity and impact on cardiac function.

Additionally, cardiac catheterization can provide valuable information about the coronary arteries and other cardiac structures that may be affected in the context of aortic stenosis. While other modalities, such as echocardiograms, are important in making the initial diagnosis and assessing valve morphology and function, they do not provide the definitive hemodynamic measurements that cardiac catheterization does.

In summary, cardiac catheterization is the definitive test for diagnosing aortic stenosis due to its capacity to offer direct measurements of the pressure gradients involved, facilitating accurate assessment of the condition's severity.