Tachycardia is a type of arrhythmia, a disorder of the rhythm of the heart, in which the heartbeat is very fast even when you are at rest. It is absolutely normal for the heartbeat to rise up during physical activities and emotional upheavals. But if you have tachycardia, your heart beats faster than normal in the upper or lower chambers of the heart, or in both, even while at rest. There are many types of tachycardia. They are classified according to the origin and cause of the abnormality. Common types of tachycardia are atrial fibrillation, atrial flutter, supraventricular tachycardia, ventricular tachycardia and ventricular fibrillation. Atrial fibrillation is caused due to irregular electrical signals in the upper chambers or atria of the heart. Atrial flutter is caused due to irregular circuitry within the atria. Supraventricular tachycardia is usually congenital and caused by abnormal circuitry, creating a loop of signals that overlap each other. The origin of this is somewhere above the lower chambers or ventricles. Ventricular tachycardia originates in the ventricles and result in the ventricles being incompletely filled with blood during pumping, thereby reducing the efficiency of the heart. Ventricular fibrillation occurs when chaotic and rapid electrical impulses cause the ventricles to quiver, instead of pumping blood. This can be fatal if not treated on time, using an electric shock to the heart, also known as defibrillation.

Tetralogy of Fallot (TOF) is a congenital defect that hampers the normal flow of blood through the heart. This disease generally occurs in a baby whose heart does not develop properly while still in the womb. The defects generally affect the structure of the heart so much that they begin to cause oxygen-poor blood flow to the parts of the body. Infants who are suffering from tetralogy of Fallot have a tinge of blue in their skin colour and have an absolute restriction of blood flow from the right ventricle. The condition, tetralogy of Fallot is also known to be associated with chromosomal abnormalities. When the flow of blood towards the lungs is limited, the fusion of the ventricular septal defect and aortic paves way for the passage of oxygen-poor blood coming back to the right atrium and the right ventricle.

The tongue is divided into two parts. The front two-thirds of the tongue is known as the oral tongue and the remaining is known as the base tongue. Cancer in the oral tongue is a type of tongue cancer. Similar to other types of cancer, tongue cancer also has different stages. The earliest it is detected and treated, the easier it is to completely remove it. Squamous cell carcinoma is the most common type of tongue cancer. These skin-like flat cells cover the mouth lining, throat, larynx, nose, and thyroid. Any cancer that occurs in these cells is known as squamous cell carcinoma. There are several causes of cancer, and smoking and heavy alcohol consumption are the most common of all. The exact cause of most oral cancers is unknown, but lifestyle habits are considered to be the main cause. Sexually contracted Human papillomavirus (HPV) is a factor that can lead to tongue cancer.

The total anomalous pulmonary venous connection comprises of a birth malformation of flow of blood where the four pulmonary veins filter into the right atrium with or without the obstruction of pulmonary veins. Pulmonary and systemic blood of veins gets mixed together in the right atrium. The four veins that carry blood from lungs to the heart do not really attach themselves casually towards the left atrium, but instead to some wrong part of the heart. It is an uncommon defect of a congenital nature that represents 2% of congenital anomalies of the heart. The veins link themselves to the left atrium or the heart by means of an unusual connection.

Tourette syndrome is a problem of the nervous system that results in sudden and involuntary movements or sounds. These sudden movements or sounds are called tics and are different for different people. Tourette’s can be severe or mild, often with onset in childhood. As a child grows, the symptoms may disappear or reduce, and for some they completely go away. The basal ganglia are a part of the brain that is linked with Tourette syndrome. Any differences in this area of the brain can affect the nerve cells. The exact cause of the problem appearing in the brain is not known, but genetics play a vital role. People with a family history of Tourette's, OCD or ADHD are more likely to develop Tourette syndrome. The Tics can vary from slight movements such as blinking or twitching and be more severe such as shaking of the head or arms. Similarly, the sounds can be mild such as clearing the throat or sniffing and may be severe like shouting or yelling out words.

The tube that connects the mouth and nose to the lungs is called as the Trachea, and the air we breathe goes in and out of the lungs through it. Trachea is placed in front of the oesophagus and it carries the food down from the mouth. It is about 5 - 6 inches long and consists of fibrous tissue rings. Tracheal Cancer is known as the cancer of the windpipe. There are different kinds of Tracheal Cancer, and squamous cell carcinoma is the most common among them. This particular kind of cancer basically happens because of smoking, but the reasons for other kinds of Tracheal Cancer are still unknown.

Transposition of great arteries is regarded as a congenital birth defect in which the two main vessels that carry blood from the heart are transposed. The transposition of great arteries paves way for a situation where the blood with a low amount of oxygen courses through right atrium and right ventricle and is pumped out to aorta and the body, while the blood rich in oxygen returns from the lungs and courses through the left atrium and ventricle and is then sent back to the lungs through the pulmonary artery. Without an adequate supply of oxygen-rich blood, the body can't function properly and the child faces serious complications or death without treatment.

Brain dysfunction as a result of any kind of external mechanical force causes traumatic brain injury (TBI). A violent blow or jolt to the head or body is usually the main cause of TBI. In the case of an object entering the skull, such as a bullet, or a piece of the skull itself may also result in TBI. A severe traumatic brain injury can lead to serious problems like torn brain tissues, bruising, bleeding, and other physical damages to the brain. Mild TBI may result in milder and temporary dysfunction of the brain cells.

If a body part gets caught between two objects in motion or under the influence of a high magnitude force, the body parts could get severely injured in the accident owing to the squeeze and rubbing. These kinds of accidents are called crush injuries. Often, the sudden shock the injured person experiences during the injury, coupled with the physical injury results in excessive trauma. Usually, such traumatic crush injuries result in broken bones, bleeding, severe bruises, laceration and compartment syndrome. Laceration refers to deep cuts or gashes in the flesh or skin, whereas compartment syndrome refers to excessive buildup of pressure in the enclosed muscle space of a human body. During a compartment syndrome episode, the increased pressure prevents blood flow into the area, thereby depriving the parts of oxygen and nourishment.

Tricuspid atresia is defined as a congenital heart defect whereby there is a complete absence of the tricuspid valve. Therefore, there is an absence of right atrioventricular connection. This leads to a hypoplastic (undersized) or absent right ventricle. Irrespective of the gender, it occurs equally both in boys and girls. In a normal condition, the tricuspid valve is positioned on the right side of the heart, whereas in the babies affected with this disease, there is no tricuspid valve at all, and the right ventricle is small. The filtering away of blue blood is not any big problem until the baby with tricuspid atresia is inside the mother’s womb. The baby will find way to pass oxygen to the lungs, provided by the mother. But once the baby is born, the levels of oxygen are lower than usual, and the fingernails and lips of the baby begin to turn blue. It becomes quite difficult for the baby to create a pathway to carry oxygen to the lungs. The disease occurs in quite rare cases, affecting 3-5 in some 20,000 births.

The head consists of 12 pairs of cranial nerves. Amongst these are the Trigeminal nerves which allows a person to feel facial sensations. A disorder to any of the three nerve branches - Ophthalmic Branch, Mandibular Branch, and Maxillary Branch, results in intense facial pain and is termed as Trigeminal Neuralgia. Trigeminal Neuralgia affects the facial nerves and causes ongoing intense pain, from the forehead to the jaw. It is similar to the feeling of electric shock like pain. The pain could be on one side or both. In case, if it happens both sides, it is called as Bilateral Trigeminal Neuralgia. The causes for Trigeminal Neuralgia could be anything, from an irritation in the nerve to a pressing blood vessel. A stroke, accident, or a surgery could also injure the nerves, resulting in Trigeminal Neuralgia.

Stenosing Tenosynovitis, commonly called ‘Trigger finger’ is the painful condition in which one of your fingers gets stuck in a bent position. Your finger may straighten with a snap sound, like a trigger being pulled and released. It occurs when there is an inflammation in the tendons of the affected finger. Tendons are tough bands of tissue that connect the muscles and the bones. Tendons and muscles function together, for the fingers to bend or straighten. The inflammation narrows down the space within the sheath of the tendons. Therefore, the motion of the tendons gets restricted and creates a pop sound during movement. Trigger finger is commonly observed in people with occupations involving repetitive gripping action in the fingers. Also, the disorder is mostly observed in women and those with diabetes.

Truncus arteriosus(TA) is a congenital heart defect having acute complexities. This disease occurs barely in one out of every 10,000 births. It does not always occur by itself, but as component of some genetic disorder. In this condition of truncus arteriosus, only one vessel appears to connect the heart to the rest of the body organs, as opposed to the two separate vessels of blood. The truncus arteriosus is a heart defect that a child gets at the time of birth. It is when the baby is still in the stage of developing and the blood vessel emerging from his heart declines to part totally, leaving both the aorta and pulmonary artery in connection with each other. In a baby with truncus arteriosus, the mixed oxygen-rich and oxygen-poor blood flows to the whole body and the lungs, and as a consequence, the heart has to exert a bit in pumping the right amount of blood to all the parts of the body.

Tuberculosis (TB) is a serious infectious disease caused by the bacteria Mycobacterium tuberculosis. This bacterial infection affects human lungs by spreading quickly, and causing damage to other organs. It is an airborne disease, and spreads through the air and can infect people who live in close proximity to each other. Smoking and consumption of tobacco and alcohol increases the risk of developing the disease. The types of TB may be regarded in two categories: active disease or latent infection., Active TB is when the disease is actively producing symptoms and can be transmitted to other people, while latent disease is when the person is infected with Mycobacterium tuberculosis bacteria, but the bacteria are not producing symptoms (usually due to the body's immune system suppressing the bacterial growth and spread) and have no TB bacteria in the sputum. They could, however, become active at any time. As per a report, TB mostly affects women aged 15 to 44 years and an average of nine million people across the globe every year.