Heart Calcium Scan
Heart calcium scan also known as Coronary Calcium Scan is what the doctor will use to look for calcium deposits in coronary arteries. Such calcium deposits can narrow arteries and thereby increase heart attack risk. The result of this scan is called Coronary Calcium Score. Heart calcium scans are non-invasive techniques to measure the amount of calcium in the walls of coronary arteries – arteries that supply heart with blood. This is an indication that they may develop coronary artery disease.
Why heart calcium scans?
These scans show a higher risk of having a heart attack or any other problems before any symptoms of heart disease become obvious. However, the American College of Cardiology does not recommend routine heart scans on people who do not exhibit any symptoms of heart disease and who do not smoke or have cardiac risk factors such as elevated cholesterol or high blood pressure.
Heart scans is useful to whom?
In those who are in intermediate heart attack risk category, a heart scan may give information about heart attack risk. Based on risk factors, having a heart attack in the next 10 years falls somewhere between 10 and 20 %. For instance, if the patient is between ages 55 and 65 years and bordering on high cholesterol or blood pressure or a smoker, then a heart scan may be considered. As there is some evidence that people with calcium scores show risk of heart disease, many would be motivated to adopt lifestyle changes, lose weight or quit smoking than those who do not undergo heart scan.
Who do not benefit from heart scans?
If a person is younger than 55 years of age and has normal cholesterol and blood pressure levels, and does not smoke, heart attack percentage is calculated less than 10 % and falls under low-risk category. Probably, in such cases, a heart scan may not reveal anything more than what the doctor already knows.
A 20 % risk or greater risk of having a heart attack in the next 10 years means at high risk. If the person is older than age 65 with high cholesterol levels and high blood pressure and does smoke, then a heart scan will not do much good because the doctor knows the risk based on risk factors and the steps to prevent a heart attack such as taking medications and making significant changes in life style. If the person has already had a heart attack or a surgical procedure, then he is at a high risk of having a heart attack and therefore a heart scan will not provide any more information on how his/her condition should be treated.
Preparing for a heart scan
It is better to visit the doctor prior to the heart scan as this can provide additional information on the heart attack risk for a doctor to consider. The examination will include:
1. A review of the medical history and the patient's family medical history.
2. A physical examination including blood pressure.
3. A risk assessment including questions about exercise and smoking habits.
4. Blood tests including cholesterol levels.
5. The doctor has to be told if a woman is pregnant. This test is not done on pregnant woman.
Other than these, there are no special preparations to have before the heart scan.
The procedure and after
A coronary calcium scan is usually done by a radiology technologist. The pictures are interpreted by a radiologist. A team of family medical practitioner, internist, cardiologist or surgeon may also review this test. Heart calcium scans takes only a few seconds and during this procedure the patient is asked to hold their breath to obtain an accurate image. The scan shows the calcium in the heart arteries by using computerized tomography (CT).
Calcium deposits show up as bright white spots on the scan. The standard imaging technique for coronary arteries uses multi slice or helical CT. In addition to calcium, such scans also reveal the presence of any narrowing of heart arteries due to coronary artery disease. After the procedure there are no special precautions and the patient should be able to drive home and continue daily activities.
If calcium score is high, it means more aggressive treatment of heart attack risk factors should be done such as life style changes or medications. The doctor may recommend more invasive tests such as coronary Angiography based on scan results. Sometimes the result of the test may not be helpful if the patient has a fast heart rate or smokes.
Heart scans such as multi slice computerized tomography and helical CT are used to see calcium in arteries. Such type of scans expose the patient to radiation. There is a slight chance of developing cancer from having coronary calcium scan. The chance is higher in those who have had many radiation. It is imperative to consult with the doctor about the amount of radiation required for this test and confirm that the test is needed. Sometimes an allergic reaction to the medication that is used during the procedure is exhibited.
The results of such scans should never be interpreted alone but should be used with information about other overall heart health and any risk factors the patient may have such as family history and high cholesterol. It is possible to have false positive results. This means that the test shows a high chance of plaque in the arteries when it is not true. Those with low chance of heart disease are most likely to have a false-positive test.
Peripheral Vascular Disease
Peripheral Vascular Disease(PVD) or Peripheral artery disease (PAD) is a condition where the arteries supplying blood to the limbs and internal organs get blocked as a consequence of atherosclerosis. Fatty deposits get built up in the arteries and reduce the flow of blood to the organs being supplied by the peripheral arteries. Atherosclerosis is by far the leading cause for Peripheral Vascular Disease. Diabetes is a condition that puts a person at high risk for PVD. Smoking and obesity increases the risk for Peripheral Vascular Disease. Persons who are obese and suffer from hypertension are at higher risk for Peripheral Vascular Disease. A sedentary lifestyle without any exercise should be avoided.
Intermittent Claudication is noticed in patients suffering from Peripheral Vascular Disease. Symptoms associated with Peripheral Vascular Disease include numbness or tingling in the limbs, sores that do not heal and pain in the buttocks. A patient suffering from Peripheral Vascular Disease notices changes in skin color and temperature. There may be a dull and cramping pain in the calf, thigh and hip muscles. Ankle Brachial Index (ABI) involves a ratio of the blood pressure in your ankle to the pressure in your arm. Angiogram is a dye test that reveals any possible blockage in the arteries. Ultrasound Doppler Test uses imaging to check for plaque build-up in the arteries. Duplex ultrasound helps in accurate detection of the size of the artery stenosis and the extent of blockage.
Medication is prescribed to eliminate the narrowing of the arteries thereby improving the heart efficiency. Anti-platelet or anti-clotting agents such as cilostazol and pentoxifylline or aspirin and Clopidogrel help in improving blood supply to the extremities. Heparin and Warfarin are anticoagulant drugs that can prevent blood clotting. Blood viscosity is controlled to improve blood flow. Drugs to control hypertension and cholesterol may also be prescribed. Bypass surgery allows a new blood route that circumvents the blocked areas of the peripheral arteries. Endarterectomy is a surgical procedure whereby a surgeon cleans out plaque buildup inside the artery of the affected leg or arm. Cryoplasty, a newer form of Angioplasty uses liquid nitrous oxide to open a narrowed artery and destroy the plaque within. Regular supervised exercise can reduce symptoms of intermittent Claudication.
Atherosclerosis is characteristic inflammatory disease of the arteries. It is triggered by a process called atherogenesis in which there is an accumulation of low density lipoproteins causing the formation of plaque. The plaque thus formed gets accumulated in the arteries causing blockage in the blood flow. The most prominent arteries prone to these plaque accumulations are the elastic and muscular arteries.
Pathology of atherosclerosis
Atherosclerosis in the initial stages appears as a fatty streak and over time it develops into a more prominent condition causing hardening of the arteries. It results in the reduction of the arterial pathway of carotid, abdominal, cardiac and other arteries of the lower and upper extremities. The etiology associated with this condition is the deposition of cholesterol and lipids in the internal lumen of the artery. These depositions are focal in origin. The disruption caused in the endothelial lining because of cholesterol accumulation leads to the emergence of inflammatory disease and arterial injuries.
Atherosclerosis triggers many conditions such as atherosclerotic heart disease, peripheral vascular disorder, coronary artery disease, and carotid artery disease. In atherosclerotic condition, some diagnostic investigations may be non-specific to the patho-physiology associated with the disease. One such test is analysis of C reactive protein which is a non-specific marker of inflammatory disease. However, the fatty streaks and associated lesions caused are identified by the characteristic smooth muscles containing lipids in it.
A fibrous plaque is formed initiating the changes in the arterial wall. The cholesterol translocation in the arterial intima (inner region) is facilitated by the lipoproteins. The fibrous streak contains collagen which is grayish white or yellow in appearance resulting in the narrowing of the blood vessel. The emergence of a complicated lesion like this can induce the formation of ulcers leading to rupture and dissemination of the accumulated plaque to various regions. This leads to the occurrence of three types of strokes. The Thrombolytic stroke which is a result of a clot or thrombus formation, hemorrhagic stroke because of blood vessel damage and embolic stroke in which the clot does not pass through the narrow artery. This eventually results in the occurrence of ischemic stroke in which there is a lack of blood supply to the brain.
Factors associated with atherosclerosis
Hypercholesterolemia is one of the main causes as it causes the low density lipo-proteins to occupy the inner layer of the artery. Elevated homocysteine levels also play an important role in the occurrence of atherosclerosis. Homocyteine levels are generally high in patients who have a history of high red meat consumption rate. Increased homocysteine levels facilitate the hardening of the arterial wall causing atherosclerotic lesions. Increased angiotensin-II concentration is also an important factor in the initiation of atherosclerotic condition as it causes vasoconstriction and associated hypertension. Other factors include infections caused by Chlamydia and Herpes viruses.
In all these factors causing atherosclerosis, the nature of inflammatory response is associated with interactions related to the monocytes, endothelial cells and T cells. In most cases, plaques or associated clots occur in the region of branching, bifurcation or curvature of the arteries. This is because of the alternating blood flow path occurring in the respective region.
The risk factors associated with atherosclerosis are mainly because of lifestyle and preexisting medical conditions. Smoking, alcoholism, obesity and hereditary factors are the predominant reasons. Other factors include diabetes, hypertension and family history of which is associated with a specific altered gene.
Patients with atherosclerosis are advised to incorporate lifestyle changes with constant watch on their eating habits. Physicians and cardiologists recommend cardiovascular exercises on a regular basis apart from medication. Surgical interventions are required in case of increased coronary artery blockage and dispersed thrombus in the blood circulation.
The plaques formed in the arterial walls of one who suffers from atherosclerosis contain significant levels of cholesterol. The risk factor of Coronary Heart Disease (CHD) rises in direct proportion to the level of LDL - Low density Lipoprotein and comes down with an increase in the HDL cholesterol. The LDL is estimated by the following formula:
LDL Cholesterol = Total Cholesterol (mg/dL) - HDL Cholesterol (mg/dL) - (Triglycerides (mg/dL)/5)
Atherosclerotic Peripheral Vascular Disease occurs owing to Atherosclerosis in Aorta and Iliac Arteries which results in Claudication (pain on exertion) or in some cases lesions in the vessels of legs ( Occlusive Atherosclerotic Lesions). The severity of the symptom can vary from time to time and usually subsides after some rest. For men, bilateral common iliac disease can often start with Erectile Dysfunction (ED).
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Bibliography / Reference
Collection of Pages - Last revised Date: November 19, 2019