Diagnosis of angina pectoris by myocardial perfusion CT

Angina is chest pain caused by a narrowed coronary artery due to a blockage or spasm. The amount of blood to feed the heart is not enough, leading to a condition where the heart is deprived of oxygen to pump blood. Angina is usually caused by coronary artery disease. The most common causes are:
Coronary artery disease: coronary arteries in the heart become narrowed due to plaque buildup from cholesterol, causing atherosclerosis, making it harder for blood to flow through them. Arrhythmia. Anemia causes a shortage of red blood cells to provide oxygen. Coronary artery spasm leads to decreased blood flow.

The basics of diagnosis:
Precordial chest pain, often triggered by stress or exertion. Rest or nitrates will provide quick relief from angina.

Signs of anemia appear when the electrocardiogram or radiograph flashes during pain or during stress testing. Coronary angiography showed marked occlusion of the major coronary arteries. The diagnosis of angina is primarily based on history, especially the following facts.
Circumstances that trigger and mildly relieve angina: Angina almost all occurs during activity, and subsides with rest. Strenuous straining of the thoracic or upper extremity muscles will trigger the pain. Patient Feelings: Patients usually do not attribute angina as "pain" but as a feeling of tightening, squeezing, burning, squeezing, suffocating, aching, like exploding chest, stuffiness, indigestion or discomfort. Pain location: In 80-90% of cases, pain is felt behind or slightly to the left of the sternum. Duration of pain: Angina attacks are usually brief and can go away completely without leaving any discomfort. Other medical history: heart disease, diabetes,...

3.1 Electrocardiogram The resting ECG is normal in one-fourth of patients with angina. Among the rest, abnormalities include: old myocardial infarction, nonspecific ST-T changes; atrioventricular or intraventricular conduction disturbances and changes in left ventricular thickening.
During angina pectoris, the ECG changes are characterized by a horizontal or descending ST-segment depression, and they are reversible after the ischemia disappears. Flat or inverted T waves may also occur. Less commonly, ST-segment elevation may be seen; This sign indicates severe (transmural) ischemia and usually occurs due to coronary vasospasm.
3.2 Stress ECG Stress testing is the most valuable exploratory method in the evaluation of patients with angina. Anemia that is not present at rest will be detected by the typical onset of chest pain or ST segment depression (or rarely, elevation).
3.3 Myocardial perfusion scintigraphy This probe shows radionuclide uptake in proportion to the blood supply at the above time point. Areas of decreased radioactivity demonstrate relative hypoperfusion (compared to other myocardial regions). In experienced laboratories, thallium 201 scintigraphy is positive in 75-90% of patients with anatomically significant coronary artery lesions and in only about 20% of these patients without lesions. . False-positive results in women may be due to the excretion of radioactive material through the mammary gland.
3.4 Radiographs of the heart chambers This procedure visualizes the left ventricle and measures ejection fraction and left ventricular wall mobility.
In coronary artery disease, abnormalities at rest correspond to infarction, while abnormalities occurring on exercise often indicate exercise-induced ischemia. Patients with coronary artery disease may find decreased ejection fraction increased with exercise.
3.5 Ultrasound Ultrasound can show the left ventricle, these abnormalities may indicate myocardial ischemia or previous infarction. It is also a good technique for assessing left ventricular function, an important indicator of prognosis and determining treatment modalities. Ultrasound can be performed in the supine stress position or immediately after standing exertion.

3.6 Coronary Angiography Coronary angiography is the gold standard for determining coronary artery stenosis and stenosis, which is one of the most accurate diagnostic methods.
3.7 Left ventricular angiography Left ventricular angiography is often performed concurrently with coronary angiography. Full or partial left ventricular function and mitral regurgitation, if present, can be seen. Left ventricular function is a major prognostic factor in stable coronary artery disease and the risk of bypass graft surgery.

CT myocardial perfusion including coronary CT angiography and stress myocardial perfusion angiography was induced by Adenosine infusion. Adenosine is a vasodilator that increases blood flow to the coronary arteries and myocardium, similar to the state in which the patient is exercising. It helps to find the cause of angina or after a heart attack to check which areas of the heart are not receiving enough blood or to assess the extent of damage to the heart muscle.
This technique is particularly suitable for patients who:
Patients > 40 years of age, Stable angina Patients at risk for coronary artery disease or atypical angina, coronary artery disease risk stratification Before surgery with or non-cardiac involvement After coronary artery bypass grafting or interventional procedure Evaluation of myocardial survival Contraindications:
Contraindications to Adenosine Unstable angina or acute chest pain suspected of acute coronary syndrome Ongoing Contraindications to Contrast and Nitromint. The patient will have a vein taken in the right hand to inject contrast, and take a vein in the left hand to heart adenosine. The medical staff will teach the patient to hold their breath during the scan, and then explain the reaction of the contrast agent and Adenosine.
The CT myocardial perfusion procedure includes assessment of myocardial perfusion under conditions of rest and exercise. After a CT scan with intravenous contrast, the doctor will evaluate and analyze areas of the heart muscle. Areas of poor perfusion are represented by hypoattenuating or non-enhanced contrast.
The time between 2 imaging procedures rest / exertion or exercise / rest is 10-15 minutes apart for the contrast to be completely eliminated.
Advantages of CT perfusion myocardium
Thin slices from myocardial perfusion CT with clear images allow assessment of lesions as small as 1cm. Therefore, this is considered a method with high sensitivity as well as specificity in coronary angiography.

Currently, Vinmec International Hospital System is using a modern computer tomography system of GE Healthcare (USA), with software to capture and analyze myocardial perfusion images. The machine can take high-definition heart and coronary arteries with any heartbeat. This is one of the modern, high-precision equipment that can greatly assist doctors in diagnosing coronary artery diseases that can cause angina.
MSc Doctor Lam Thi Kim Chi graduated with a Master's degree in Radiology - Hue University of Medicine and Pharmacy and has over 6 years of experience as a radiologist. Doctor Chi used to work at Da Nang Obstetrics and Gynecology Hospital before working as a radiologist at Vinmec Danang International General Hospital as it is today.