SPECT
SPECT or Single Photon Emission Computed Tomography is a diagnostic tool that that uses gamma camera to collect gamma rays that are emitted from the patient. Radioactive isotope is adminstered to the patient either as injection or inhalation or ingested liquid. SPECT imaging helps acquire multiple images from multiple angles. The gamma camera is rotated around the patient. Dual-headed cameras can help in accelerating the test. Often triple-headed cameras are also used. SPECT is particularly useful in imaging of tumors, bones, thyroid and infections. Cardial imaging and brain imaging provide critical information about localized functions. MPI (Myocardial perfusion imaging) is an important cardiac stress test. SPECT images allow diagnosis of ischemic heart disease. This test is comparable to stress echocardiography. SPECT imaging of the brain aids in distinguishing Alzheimer's disease from other vascular dementias. Nearly 30 or more images are taken of the specific body area that is being viewed. SPECT scanning is time consuming.
Cardiologist
Cardiologists are physicians who diagnose and treat ailments related to the cardiovascular system that comprises of the heart, arteries, and veins. Pediatric cardiologist is a physician who focuses on diagnosing and treating heart problems in infants, children and young adults. Cardiologists specialize in treatment of angina (chest pain), heart attack, heart failure, high blood pressure and irregular heart beats. A cardiologist has to complete medical school and undergo residency in internal medicine for a period of three years. Further three years of specialization in the field of cardiology is required. For pediatric cardiologists a specialization in pediatrics is required prior to cardiology specialization. Cardiologists are specialists who provide complete heart care; they can determine the working condition of a person's heart by means of different tests. The responsibilities of the cardiologist include:
- The primary function of a cardiologist is to check on how well a person's heart is working.
- They determine this by asking for various tests like the treadmill test (exercise electrocardiogram), and through procedures like angioplasty, cardiac catheterization etc.
- They offer treatments for the diagnosed heart diseases through interventional cardiology like angioplasty, where a mechanical device is used to set right the problem in the heart.
- They use electrophysiology that helps in treating the electrical functioning of the heart.
- They also have the additional responsibility of keeping control over the factors that determine the health of the heart such as blood pressure and cholesterol levels. These levels in the blood of a person are kept under control thus keeping the heart comfortably functioning.
Modern techniques used in the field of cardiology
With the advancement in the field of medicine, cardiologists have the access to the latest technologies like:
Auscultation: A stethoscope is used to identify and detect heart abnormalities and murmur in the heart.
Echocardiography: Ultrasonic waves are used to visualize the heart.
Electrocardiography: EKG instruments are used to monitor the electrical activity of the heart.
Holter monitor: Records the EKG for 24 hours and more non-stop.
Modern blood tests: Determining the levels of HDL, LDL, triglycerides, homocysteine, and C-reactive protein helps in easy identification of heart problems.
Stress testing: Determines the levels of stress and cardiac function of the heart.
Coronary catheterization: Functioning of the heart is determined by inserting catheter into the heart.
Acardia
Acardia is a rare and serious malformation that occurs exclusively in monizygous twins - twins developing from a single egg. Acardia represents one of the most severe and rare congenital anomalies. It is characterized by the absence of functioning heart. Acardia results from the artery to artery connections in the placenta, thereby causing a physically normal fetus to circulate blood for itself as well as a severely malformed fetus suffering from heart regression. In other words, fetus acardius is a parasite and it receives blood supply from the donor twin. Because the pump twin heart has to pump for two, there is a high risk of going into heart failure and this would lead to the death of the normal twin.
The most common variety is the acardius acephalus where the head is lacking and so are the upper extremities. Other types are acardius anceps, acardius acormus and acardius amorphous. While in acardius anceps, the most highly developed form, a partly developed head with remnants of cranial bones and brain tissue are present with developed body and extremities, acardius acormus is the rarest form of acardia. The monster is a head without a body. Acardia amorphous is the least developed monster not recognizable as a human form, with minimally developed visceral organs. Since there is no gross human form, the name acardius amorphous.
As to the cause of acardia, the etiology of acardiac monster is still unknown. Genetic defects have been reported to be the cause. Some researchers suggest chromosomal abnormalities to be the reason. Krause and Bejdl suggest that compression of the cephalic pole of the embryo prohibiting curving and fusion of the primitive heart tube to be the basic cause of this anomaly. As a result, the dependant entodermal organs like thyroid, oesophagus, trachea, lung, liver and others are also not formed.
A pregnant woman carrying an acardiac twin is unlikely to have any unusual symptoms. An acardiac twin is often found incidentally on prenatal ultrasound. As no two acardiac twins are formed exactly alike, they may present differently. Several improved imaging techniques like 2D ultrasonography, 3D ultrasonography and transvaginal Doppler ultrasonography have made diagnosis of acardia possible even in the first trimester of pregnancy. Such early diagnosis helps to reduce the risk of complications. Fetal echocardiography is also recommended to assist in early detection of heart failure in the normal twin. Chromosome studies are also done on both fetuses.
One line of treatment is watching for the earliest signs of heart failure in the pump twin with frequent ultrasounds. If heart failure is identified and the pregnancy is also far enough, then the pump twin should simply be delivered. Physicians recommend prenatal interruption of the blood vessel connections before heart failure develops in the pump twin, thus sacrificing the acardiac twin.
Specialists use laser, electrical cauterization and electrodes, serial amniocentesis, medications and other treatments successfully. If the acardiac twin is large enough and the amount of blood flow to it can cause heart failure in the healthy twin, then blood flow is stopped with Fetal Image-Guided Surgery. The acardiac or parasitic twin never survives, as it is severely malformed and does not have a functioning heart. The normal twin is at risk for heart failure and complications associated with premature birth. The normal twin is expected to have about 10% risk for malformations.
Bibliography / Reference
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