Heart Bypass Surgery
The blood supply to the cardiac muscle is through the coronary arteries. The coronary arteries are located in the anterior and posterior locations of the heart giving a branched appearance. The width of each coronary artery is 3-4 mm and it continues throughout the cardiac muscle as small branches supplying blood to the entire heart.
Heart Bypass surgery
The cardiac muscle experiences ischemia or lack of blood supply if there is an impairment in the coronary artery. The function of the coronary artery is affected due to fatty deposits or plaque. These fatty deposits block the blood supply through the coronary artery. In this situation, the patient begins to experience chest pain and discomfort. Angina can lead to cardiac arrest if not treated immediately. The coronary artery is either partially clogged or totally clogged in these conditions. One of effective ways to treat this condition is through a surgical procedure called Coronary artery bypass graft or CABG.
The bypass procedure of the heart is an intricate and meticulous procedure involving a team of cardiac surgeons, anesthetist and perfusionist. The patient is administered general anesthesia as it is an invasive procedure. The CABG can be done in two ways, the first one involves the maintenance of circulation through the heart-lung machine operated and monitored by the perfusionist during the procedure. Here, the heart is stopped for about 30 - 90 minutes. The second one is called the Beating heart surgery or Off Pump surgery, in which the procedure is done on a beating heart. This is safer for patients who are at increased risk of complications, such as those suffering vascular disease, aortic calcifications, carotid artery stenosis or breathing or kidney problems. Other procedures are minimally invasive bypass surgery and robotic-assisted bypass surgery.
The entire CABG is categorized in two phases. In the first phase, a healthy blood vessel is taken to create the bypass near the region where the coronary artery is blocked. The graft is taken either from the arm (radial artery), chest (internal mammary artery) or legs (saphenous vein). Since there are other blood vessels connecting these tissues, it is safe to use them. Depending on the location, amount and size of the blockage, the choice of substitute blood vessel is made. In the second phase, the surgeon creates the bypass route from the clogged site of the coronary artery to generate a healthy supply region for the cardiac muscle. The duration of the procedure ranges from 3-6 hours depending on the number of grafts the patient requires. Patients are transferred to critical care units after surgery and generally kept under admission for a period of six to nine days.
Postoperative care in CABG
The risk factors associated with the CABG procedure include heart rhythm problems, kidney or lung failure, chest wound infection and memory malfunction. Postoperative care plays an important role in retaining the normal function of the heart. Patients notice a swelling at the site of incision which gradually subsides after a few weeks. Postoperative experience in CABG requires rehabilitation as many patients complain of anxiety, lack of sleep and anorexia. Patients are advised to abstain from activities such as heavy lifting, driving and climbing stairs. Cardiac rehabilitation techniques aid the patients in improving their cardiac endurance levels and also creating an optimistic mind set after surgery. Medication and exercise in moderate levels subsequently improve the functionality of the heart; however patients are advised to avoid foods containing trans-fats and smoking.
Cardiac catheterization is a test which is performed to obtain certain diagnostic information about the heart. Patients may require this medical therapy rather than undergo angioplasty or bypass surgery when they suffer from rare or easily controlled episodes of angina. Alternatively, cardiac catheterization is not performed in patients who have infrequent episodes of angina and in whom angina can be easily controlled. When a patient has heart failure due to suspected coronary artery disease or there is suspected coronary artery disease, cardiac catheterization is conducted. Cardiac catheterization can help:
The patient is asked not to drink or eat anything, except a small amount of water, for at least 6 to 12 hours before the test. The patient is tested for allergy to iodine or other medications. Patients suffering from kidney disease or diabetes or bleeding disorders must keep the cardiologist informed. The cardiac catheterization test is performed in a cath lab by a cardiologist. The actual catheterization procedure takes about 15 - 30 minutes. The patient's electrocardiogram that continuously records the electrical activity of the heart is taken.
A pulse oximeter device that measures the oxygen levels of the patients' blood is monitored. An intravenous needle is inserted into the patients' vein to give fluids or medicine during the catheterization procedure. A sedative is also given through this IV line which helps the patient to relax.
Cardiac catheterization procedure involves passing a catheter, a thin flexible tube, into the right or left side of the heart. The doctor inserts this thin plastic tube into the groin - femoral artery. Other places where in the catheter may be inserted are the elbow- brachial artery or the wrist - radial artery. From there it is slowly advanced into the chambers of the heart or into the coronary arteries. The doctor watches the progress of the catheter into the heart's vessels and chambers on the imaging screen. Pressures within the heart chambers are measured and the blood and tissue samples are also removed through the catheter. A small amount of dye is also injected through the catheter into the heart chamber or into one of the coronary arteries.
Therapeutic catheterization: Certain types of heart defects can be repaired using catheterization. For instance, if the coronary arteries are blocked, the cardiologist can use a catheter, guide wire and balloon to open and improve blood flow to the heart. This is termed as percutaneous coronary intervention (PCI).
Normal result indicate that there is no significant narrowing or blockage in the coronary arteries. Abnormal results may suggest that the heart does not pump blood normally or the valves in the heart may be weak. There may be leakage between heart chambers. There is a possibility of aortic aneurysm. Some complications with cardiac catheterization include heart attack or stroke, hematoma, puncture of the heart or arrhythmia.
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.
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Bibliography / Reference
Collection of Pages - Last revised Date: September 21, 2020