Ischemic Heart Disease – About the Examinations
For diagnosing ischemic heart disease, information such as ‘what are the symptoms’, ‘what triggers the symptoms’, and ‘underlying conditions like diabetes or chronic kidney disease’ is crucial. Based on this information, we consider and propose the most appropriate examination method for each individual patient.
Exercise Stress Electrocardiogram
This is an examination that measures the electrocardiogram while exercising. It is relatively simple and does not involve radiation exposure or drug administration.
By walking on a treadmill (like those in a gym), or in some cases brisk walking, we can observe changes in the ECG during exercise to estimate the presence of ischemic heart disease. While this test is simple and doesn’t involve medication or radiation exposure, its accuracy is somewhat lower compared to other tests. Therefore, we select the appropriate test based on the individual situation.
Coronary CT Angiography (FFRCT)
This is a relatively simple and highly accurate examination that can visualize not only narrowed areas of the heart’s blood vessels (coronary arteries) but also the degree and nature of arteriosclerosis. This examination uses CT (Computed Tomography) to visualize the coronary arteries. With advancements in equipment, coronary CT can clearly depict the condition of thin coronary arteries about 2-4mm in diameter, allowing us to instantly see which parts of the coronary arteries have issues. In addition to identifying narrowed blood vessels, it can simultaneously reveal the nature of plaques in the coronary arteries (whether they are prone to rupture or heavily calcified). While this examination involves a certain amount of radiation exposure (equivalent to or less than CT scans of other organs), it causes little discomfort to patients. Due to its high diagnostic accuracy, its use is expanding worldwide.
Additionally, this examination can be supplemented with an FFRCT examination, which performs computer-based blood flow simulation on three-dimensional (3D) reconstructed CT images. The FFRCT examination can determine whether a narrowed vessel seen in the image is actually causing reduced blood flow, helping to decide if further invasive tests like catheterization are necessary.
For more details, please see here.
Coronary CT examination requires special CT equipment to capture images of the moving heart. Before the scan, medication is taken to slow the heart rate. As this test generally uses contrast agents, it cannot be performed on patients with allergies to iodine-based contrast agents or those with severely impaired kidney function.
Myocardial Perfusion Imaging (SPECT)
This examination can confirm the extent of heart muscle (myocardium) exposed to reduced blood flow due to arteriosclerosis in the heart’s blood vessels (coronary arteries). It can be safely performed even on patients with severely impaired kidney function.
This test involves injecting a radioactive isotope during exercise stress or pharmacological stress to assess blood flow uptake in the myocardium (heart muscle). If the area of myocardium exposed to reduced blood flow (ischemia) due to narrowed coronary arteries is extensive, treatment options such as catheter intervention or bypass surgery may be considered. This examination typically involves two imaging sessions in one day: one after stress and one at rest. While it involves radiation exposure similar to coronary CT (effective dose of about 8 mSv), it has the advantage of not using contrast agents. Therefore, it can be performed on patients with severely impaired kidney function.
Cardiac MRI Examination
This examination does not involve radiation exposure and can visualize the heart’s blood vessels (coronary arteries) while also providing information about the heart muscle (myocardium).
MRI examinations for the heart differ between those looking at the myocardium and those examining the coronary arteries. Coronary MRI examination (MRA) does not require contrast agents and has no radiation exposure. However, its image quality is lower compared to coronary CT, so the choice of examination is made based on the situation.
There is also a perfusion MRI examination that can check if the blood flow uptake in the heart muscle (myocardium) has decreased due to narrowed coronary arteries. It can also confirm the extent of dead (necrotic) heart muscle cells after events like myocardial infarction. These examinations use MRI-specific gadolinium contrast agents.
Coronary Angiography (Catheter Examination)
This is the most accurate examination for assessing the condition of the heart’s blood vessels (coronary arteries) and is performed on patients with a high likelihood of ischemic heart disease. At our hospital, it can be done as a ‘day procedure’ or with a ‘one-night, two-day hospitalization’.
For more details about the examination and treatment process at our hospital, please refer to here.
When ischemic heart disease is suspected based on the above examinations, or in cases like acute myocardial infarction where ischemic heart disease is highly suspected without the need for the above tests, we perform catheter-based coronary angiography to confirm the presence of this disease. The catheter used in coronary angiography is a long, tubular device with a diameter of 1.3-1.7mm. It is often inserted through an artery in the wrist and guided through blood vessels to reach the heart, where it is inserted into the entrance of the coronary arteries. Contrast agent is injected through the catheter into the coronary arteries, and the condition of the coronary arteries is observed using X-ray fluoroscopy. This examination, which directly inserts a catheter into the coronary arteries for imaging, provides higher image quality and more accurate assessment of coronary artery condition compared to CT or MRI imaging of the coronary arteries.
Additionally, catheter examination includes a test called FFR, which measures how much blood flow is reduced in narrowed coronary artery lesions. It’s known that if blood flow is maintained even in narrowed vessels, the heart receives sufficient oxygen and nutrients, and in such cases, catheter treatment to widen the vessel is unnecessary (and would not be effective). Therefore, when moderate coronary artery stenosis is found, FFR examination is crucial for determining the need for catheter treatment*. In FFR examination, a thin (0.36mm) wire called a pressure wire, equipped with a pressure sensor, is passed through the coronary artery lesion. The pressure measured within the coronary artery is used to calculate the degree of blood flow reduction using a specialized machine (console).
At our center, catheter examinations are performed as either a ‘day procedure’ or a ‘one-night, two-day hospitalization’. For day procedures, patients typically arrive in the morning and return home in the early afternoon (we do not perform day-procedure treatments).
* In cases where angiography shows severe narrowing (over 90% stenosis), it’s clear that blood flow is reduced, so this type of examination may not be performed. Also, if reduced coronary blood flow (ischemia) has been confirmed by FFRCT examination, myocardial perfusion imaging, or perfusion MRI, FFR examination is usually not performed.
