ECG is a transthoracic interpretation of the electrical activity of the heart over time captured and externally recorded by skin electrodes.It is a noninvasive recording produced by an ECG device.
The ECG works mostly by detecting and amplifying the tiny electrical changes on the skin that are caused when the heart muscle "depolarises" during each heart beat. At rest, each heart muscle cell has a charge across its outer wall, or cell membrane. Reducing this charge towards zero is called de-polarization, which activates the mechanisms in the cell that cause it to contract. During each heartbeat a healthy heart will have an orderly progression of a wave of depolarisation that is triggered by the cells in the sinoatrial node, spreads out through the atrium, passes through "intrinsic conduction pathways" and then spreads all over the ventricles. This is detected as tiny rises and falls in the voltage between two electrodes placed either side of the heart which is displayed as a wavy line either on a screen or on paper. This display indicates the overall rhythm of the heart and weaknesses in different parts of the heart muscle.
X-ray angiography is performed to specifically image and diagnose diseases of the blood vessels of the body, including the brain and heart. Traditionally, angiography was used to diagnose pathology of these vessels such as blockage caused by plaque build up. However in recent decades, radiologists, cardiologists and vascular surgeons have used the x-ray angiography procedure to guide minimally invasive surgery of the blood vessels and arteries of the heart. In the last several years, diagnostic vascular images are often made using MR, CT and/or ultrasound and while x-ray angiography is reserved for therapy.Most angiography procedures are carried out using local anaesthetic to numb the area where the catheter is going to be inserted. General anaesthetic is sometimes used for young children.The procedure will be carried out by a specialist, such as a cardiologist (a doctor who specialises in heart disease) or a radiologist (a doctor who specialises in using imaging studies). A nurse may also be present to assist with the procedure. An intravenous (IV) line will be inserted into a vein in the arm. It can be used to deliver sedatives or any other medication as required. Electrodes (small, metallic discs) may be placed on the persons chest to record the heartbeat. A blood pressure monitor may also be attached to your arm.A small plastic tube called a sheath will be placed into one of your arteries. A catheter (a long, thin flexible tube) is inserted through the sheath and on to the arteries being examined. Depending on the area being examined, the catheter is usually inserted into an artery in your wrist or groin.
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