CARDIAC ECHO (ULTRASOUND)
Cardiac ultrasound is a simple non-invasive test that uses ultrasound waves to build up detailed moving pictures of the heart chambers and valves. The patient is placed on a couch in the recumbent position and a probe is placed on the surface of the chest with some gel, to allow passage of the soundwaves. The study takes approximately 30 minutes and builds up a detailed picture of the heart in action. It is then interpreted by the Cardiologist and allows diagnosis of conditions such as left and right ventricular failure, abnormal heart valve problems such as aortic stenosis or mitral regurgitation, the presence of abnormal fluid in the space around the heart, called pericardial effusion.
The ECG is a surface recording of the electrical activity of the heart. It takes approximately 5 minutes and is performed as an outpatient. It involves the placing of disposable electrodes on the surface of the chest, the patient lies still on the couch. The recording is completed and the recordings then interpreted by the Cardiologist
TREADMILL EXERCISE ECG
The individual is connected to ECG monitoring wires and then walks on the treadmill at progressively increasing pace and incline. It allows the Cardiologist to understand how the heart responds to the workload of exercise. It also allows the Cardiologist to assess the response of blood pressure to exercise and the overall fitness of the individual. It is a very useful test for assessing heart performance, but can also be used to look for evidence of abnormalities in the coronary arteries, as these may show up during the test. It takes approximately 40 minutes from beginning to end, although the actual walking phase usually lasts no longer than 12 minutes. A variety of protocols are available for people of different fitness levels, so that even those with limited exercise capacity can perform a meaningful treadmill test at a more gentle workload.
CT CALCIUM SCORING
The process of atherosclerosis, i.e., the build-up of cholesterol deposits in the arteries is an inflammatory process and leads to micro deposits of calcium in the arteries. Over time, these coalesce, and these calcium deposits in the wall of the artery can be seen vividly on CT scanning. The CT scan is a fixed slice scan and therefore is a very low dose scan and it takes a matter of seconds. The overall procedure takes approximately 15 minutes. At the end of the calcium scan, a score is calculated called the Agatston score, and based on the Agatston score, the individual can be assessed as having no coronary disease or intermediate or high risk of coronary disease, and consequent to this, further investigations can be scheduled.
HIGH RESOLUTION CT CORONARY ANGIOGRAPHY
This allows the construction of highly detailed road maps of the coronary arteries without the need for invasive technique. The patient is prepared and lies comfortably on the CT table, a tiny cannula is placed in the back of the left hand. If necessary, the patient is given a very small dose of intravenous beta blocker, which is short acting, to bring the heart rate down, and some nitrate spray will be administered under the tongue. This allows maximum dilation of the coronary arteries for the best possible scan quality. After a scouting scan is performed, a small dose of intravenous contrast agent is administered to the patient, and as this flows from the vein through the heart and into the coronary arteries, ultrafast CT scanning is performed, synchronised with the heartbeat, to allow the construction of multiple slices of information. The slices are then re-assembled digitally to perform a 3D map of the arteries as illustrated. The radiation does are extremely small and the scan quality and its prognostic and predictive power extremely high. The whole test from beginning to end takes approximately 30 minutes.
INVASIVE CORONARY ANGIOGRAPHY
Invasive coronary angiography is the gold standard test for assessing coronary artery disease. It is usually performed as a day case procedure. After admission, the individual is brought into the cardiac catheterisation laboratory and lies on a comfortable radiolucent table that allows x-rays to pass through. Under local anaesthesia, a tiny cannula sheath is inserted into either the radial artery in the wrist or the femoral artery at the top of the leg, and through this small plastic sheath all of the cardiac catheters pass. Because there are no nerves inside the cardiovascular system, there is no need for general anaesthesia or analgesia, and the test is very well tolerated by almost every patient. Using specially shaped cardiac catheters, the catheters are placed at the opening of each coronary artery in turn and a radiopaque contrast agent is injected during x-ray screening and video acquisition. This allows ultra-high resolution images of the coronary arteries to be acquired and demonstrates clearly any narrowings or obstructions in the arteries and aids treatment planning. If necessary, at the same sitting, the operator can follow on the diagnostic pictures with any interventions required, such as balloon angioplasty and stent implantation, to restore blood flow down narrowed or blocked arteries.
STRESS CARDIAC MAGNETIC RESONANCE SCAN
Cardiac magnetic resonance imaging is a highly specialised test that allows the measurement of blood flow through the heart muscle itself to be calculated. Using a special tracer called gadolinium, the magnetic resonance scan looks at the flow of gadolinium through the heart during rest and stress, and also allows detection of areas of scar tissue, inflammation or fibrosis within the heart muscle. It can also be used to measure very accurately blood flow through the heart and back flow through any leaking heart valves. The whole procedure takes 90 minutes to 2 hours and can be performed either in a closed scanner, which some people find uncomfortable, or an open scanner where there is much more open space and less sense of enclosure. The scanner at 27 Harley Street is an open scanner, and with the skill and care of the imaging team there, we have not had to date a single patient who has been unable to complete the scan. It is a very useful scan for assessing abnormalities in the arteries that might be detected on CT, without the need for invasive cardiac catheterisation. It is also extremely useful for treatment planning if multiple narrowings are found in coronary arteries and the decision needs to be between stents or bypass surgery.
A coronary angiogram (or arteriogram) is an x-ray of the arteries located on the surface of the heart (the coronary arteries). It helps the physician to see if any of those arteries are blocked, usually by fatty plaque. If so, the patient may be diagnosed with coronary artery disease (CAD). A coronary angiogram is often conducted along with other catheter-based tests as part of cardiac catheterisation, which also includes measuring blood pressure, taking samples for blood tests, and a left ventriculogram. During an angiogram, the physician injects a special dye (contrast medium) into the coronary arteries. To do that, the physician inserts a thin tube (catheter) through a blood vessel, usually in the upper thigh, and guides it all the way up to the heart. Once the catheter is in place, the physician can inject the dye through the catheter and into the coronary arteries. Then the x-ray can be taken. Although the physician typically numbs the area where he or she inserts the catheter, the patient is awake for the entire procedure. The patient receives a mild sedative before the procedure and does not ordinarily feel the movement of the catheter within the blood vessels. Depending on what the angiogram shows, the physician may recommend treatments such as medication, a catheter-based procedure (e.g., balloon angioplasty, coronary stenting) or surgery (e.g., bypass surgery).
A TOE is an ultrasound scan of the heart performed by passing a probe on the end of a flexible scope into your oesophagus (the ‘food pipe’). The scope is similar to the ‘camera’ used to look for a stomach ulcer. The oesophagus lies directly behind the heart, with no intervening structures, so the images are much clearer than those from the front of the chest (transthoracic echocardiography), where the chest wall, ribs and lungs get in the way. TOE is particularly useful to look at the mitral valve and to find holes in the heart, blood clots or evidence of infection (endocarditis).
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