Q: I was referred by my family doctor to a cardiologist who recommended an echocardiogram. Could you tell me the purpose of this procedure and how it is done?
A: An echocardiogram is the image produced by applying techniques using ultrasound to the heart.
Ultrasonography uses an external device to transmit brief pulses of high-frequency sound into the body. The sound wave signals echoed back from body tissues are picked up by the same device and converted to a picture of the anatomical features on the chest, but for some diagnostic purposes may be positioned inside the esophagus or food tube using a gastroscope.
Without more information I can not guess why an echocardiogram was recommended for you. However, echocardiography is an effective technique for the diagnosis of abnormalities of the heart valves; alterations in the wall thickness or function of the heart's lower chambers; blood clots or tumors within the heart chambers; disorders of the heart muscle and some types of congenital heart disease.
The advantages of ultrasonography are its relatively low cost and safety, since no ionizing radiation is involved.
Q: I would like to know what "respiratory alkalosis" is. What causes it, what effects does it have on the body and what are its dangers?
A: The body makes large amounts of acid (hydrogen ion or H+) every day. The amount of H+ in the blood and other body fluids is closely regulated, primarily by the lungs, but also by the kidneys. The lungs reduce the amount of acid in the body by excreting carbon dioxide when you breathe out.
An accumulation of excessive H+, termed acidosis, is a common medical problem. In respiratory acidosis, for example, diseases of the lungs interfere with the excretion of carbon dioxide.
Respiratory alkolosis results when overly vigorous breathing eliminates so much carbon dioxide that the H+ in body fluids drops below normal. The most common cause of respiratory alkolosis is so-called hyperventilation syndrome, usually caused by an anxiety attack.
During an attack, people gulp for air, feel short of breath, any may feel a numbness and tingling in the fingers and around the mouth. Severe respiratory alkolosis may cause tetany, a sharp flexing of the wrist and ankle joints, and muscle twitchings. All of these symptoms fade quickly when the alkolosis is reversed by stopping the hyperventilation. The blood level of carbon dioxide can be restored rapidly by breathing in and out into a paper bag or by holding your breath.
Severe respiratory alkolosis may complicate the management of patients with an artificial ventilator. People with liver disease or brain disorders may develop mild respiratory alkolosis for which no treatment is needed.
Q: My eye doctor told me I have normal vision in the left eye but 20/50 vision in the right. What does that mean?
A: "Perfect" (20/20) vision is arbitrarily defined as what a person with a normal eye can read in daylight at a distance of 20 feet. The finding of 20/50 vision in your right eye means that, when your left eye is covered, you have to be 20 feet away from the eye chart to read what a good eye can see from 50 feet. The extent of visual impairment is greater when the second number is larger.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for faculty affairs at the school.