Top videos
Retinitis pigmentosa is a rare, inherited degenerative eye disease that causes severe vision impairment. Symptoms often begin in childhood. They include decreased vision at night or in low light and loss of side vision (tunnel vision).
ICDs are useful in preventing sudden death in patients with known, sustained ventricular tachycardia or fibrillation. Studies have shown ICDs to have a role in preventing cardiac arrest in high-risk patients who haven't had, but are at risk for, life-threatening ventricular arrhythmias. View an animation of an ICD. Newer-generation ICDs may have a dual function which includes the ability to serve as a pacemaker. The pacemaker feature would stimulate the heart to beat if the heart rate is detected to be too slow. What is an Implantable Cardioverter Defibrillator (ICD)? An ICD is a battery-powered device placed under the skin that keeps track of your heart rate. Thin wires connect the ICD to your heart. If an abnormal heart rhythm is detected the device will deliver an electric shock to restore a normal heartbeat if your heart is beating chaotically and much too fast. ICDs have been very useful in preventing sudden death in patients with known, sustained ventricular tachycardia or fibrillation. Studies have shown that they may have a role in preventing cardiac arrest in high-risk patients who haven't had, but are at risk for, life-threatening ventricular arrhythmias.
McMurray's maneuver is used to detect the presence of meniscal tears. To detect a medial meniscal injury, the patient is put in a supine position with the knee in maximum flexion. One hand of the examiner is placed on the posteromedial margin of the involved knee and the other hand supports the foot. The tibia is then externally rotated, and the knee is extended slowly. The test is positive if there is an audible or palpable click or popping sensation during extension of the involved knee.
A nephron (from Greek νεφρός (nephros) meaning "kidney") is the basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine.
Coarctation of the aorta (CoA[1][2] or CoAo), also called aortic narrowing, is a congenital condition whereby the aorta is narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts. The word “coarctation” means narrowing. Coarctations are most common in the aortic arch. The arch may be small in babies with coarctations. Other heart defects may also occur when coarctation is present, typically occurring on the left side of the heart. When a patient has a coarctation, the left ventricle has to work harder. Since the aorta is narrowed, the left ventricle must generate a much higher pressure than normal in order to force enough blood through the aorta to deliver blood to the lower part of the body. If the narrowing is severe enough, the left ventricle may not be strong enough to push blood through the coarctation, thus resulting in lack of blood to the lower half of the body. Physiologically its complete form is manifested as interrupted aortic arch
A Bone scan or bone scintigraphy is a nuclear scanning test to find certain abnormalities in bone which are triggering the bone's attempts to heal. It is primarily used to help diagnose a number of conditions relating to bones, including: cancer of the bone or cancers that have spread (metastasized) to the bone, locating some sources of bone inflammation (e.g. bone pain such as lower back pain due to a fracture), the diagnosis of fractures that may not be visible in traditional X-ray images, and the detection of damage to bones due to certain infections and other problems.
Nuclear medicine bone scans are one of a number of methods of bone imaging, all of which are used to visually detect bone abnormalities. Such imaging studies include magnetic resonance imaging (MRI), X-ray computed tomography (CT) and in the case of 'bone scans' nuclear medicine. However, a nuclear bone scan is a functional test, which means it measures an aspect of bone metabolism, which most other imaging techniques cannot. The nuclear bone scan competes with the FDG-PET scan in seeing abnormal metabolism in bones, but it is considerably less expensive.
Nuclear bone scans are not to be confused with the completely different test often termed a "bone density scan," DEXA or DXA, which is a low exposure X-ray test measuring bone density to look for osteoporosis and other diseases where bones lose mass, without any bone re-building activity. The nuclear medicine scan technique is sensitive to areas of unusual bone re-building activity because the radiopharmaceutical is taken up by osteoblast cells which build bone. The technique therefore is sensitive to fractures and bone reaction to infections and bone tumors, including tumor metastases to bones, because all these pathologies trigger bone osteoblast activity. The bone scan is not sensitive to osteoporosis or multiple myeloma in bones, and therefore other techniques must be used to assess bone abnormalities from these diseases.
The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to (and stimulate) the cardiac muscle (myocardium). The myocardium contracts after stimulation.