Echochocardiography
Echocardiography uses ultrasound to assess the structure and function of the heart chambers and of the heart valves, providing real-time views of the heart in motion and of the blood flow through the heart. Three-dimensional echocardiography is used to obtain views of the heart very similar with what the heart surgeon sees on direct inspection at the time of surgery. Images are recorded and stored for analysis and future reference (for example comparison at follow-up).
Echocardiography comprises transthoracic echocardiography, contrast echocardiography, stress echocardiography and transoesophageal echocardiography.
Transthoracic Echocardiography (TTE)
TTE obtains images of the heart by placing on the chest an ultrasound transducer covered in water-based gel to enhance the transmission of ultrasound through the chest wall. This test implies no or minimal discomfort for the patient and no side effects, so it can be repeated as many times as necessary during follow-up.
Contrast Echocardiography
Contrast echocardiography uses an injected dye (contrast) to highlight certain heart features. When the dye used is simply saline (sterile salty water) shacked to become bubbly, the test is named bubbles study. Bubbles studies are used to detect small hole in the heart, by observing the bubbles crossing from one side of the heart to the other. When contrast echocardiography is used to detect a clot or subtle changes in the contraction of the heart muscle, a manufactured dye is injected.
Stress Echocardiography
Stress echocardiography uses images of the heart during stress to make a diagnosis. Exercise is a natural form of heart stress and is used whenever the patient can exercise on a treadmill or on a supine bicycle. The test using exercise is named exercise echocardiography. Treadmill exercise is used, for example, to detect changes in the contraction of the heart muscle as a result of narrowing in the arteries of the heart (coronary arteries). Supine bicycle is used to assess changes in the function of the heart valves and in the pressure inside the heart chambers. When the patient cannot exercise, heart stress can be obtained by injecting a drug in a drip to make the heart beat faster and stronger. The most commonly used drug is dobutamine and the test using dobutamine is named dobutamine stress echocardiography (DSE). DSE is used mainly to assess the heart when narrowing of the coronary arteries is known or suspected.
Transoesophageal Echocardiography (TOE)
TOE obtains images of the heart by inserting an ultrasound transducer in the gullet through the mouth. TOE images are much clearer than TTE images, because the gullet seats just behind the heart, so the ultrasound does not have to cross the chest wall and the lungs to reach the heart. However, being semi-invasive, the test is used only when absolutely necessary. Sedation or general anesthesia and a throat spray with local anaesthetic are used to minimize discomfort during the test. TOE is not only used as a diagnostic test, but also to guide key-hole procedures and during heart surgery for planning and assessment of the result.