Medical Technologies

Various invasive and non invasive techniques are used for the diagnosis of diseases. Some important medical technologies are briefly described here


It is the graphical representation of the electrical activities of the heart. Waller in 1887 first recorded ECG and Einthoven is considered as the Father of Electrocardiography. ECG is represented by five waves (PQRST). P-wave represents depolarization of auricles, QRS- depolarization of ventricles, PQ- contraction of auricles, QR- spread of excitation of SA node, RS- spread of excitation of AV node and T- repolarization of ventricles. R- is the wave with largest amplitude.

ECG – Electro Cardio Gram
P-De polarization of Atria. Activation of SA node
QRS-De polarization of Ventricles
PQ-Atrial contraction
QR-Spread of excitation from SA node to AV node
RS-Spread of excitation from AV node to Purkinje system
T-Repolarization of Ventricles
R-It has the largest Amplitude.

EEG – Electro Encephalo Gram
It is obtained by placing electrodes on the scalp. Brainwaves are recorded in the EEG. The different forms of brain waves are

Alpha wave – when a person is awake with eyes closed. Frequency is 8-13 cycles per second.
Beta wave – when a person is awake with eyes open.
Theta wave – moderate sleep.
Delta wave – deep sleep. Very low wave – 4-7 cycles per second and large amplitude.
REM sleep – produces same wave as the person is in the waking stage.

Also called Sonography Used to image Aorta, Heart valves, Heart wall etc. It is also used to record blood
flow velocity and blood turbulence

Vector cardiography
To analyze Q wave and Intra ventricular conduction abnormalities

Super conducting Quantum Interference Device. E.g. Magneto encephalograph.

Magneto Encephalographic Technique and SQUID are used to give information about the healt
of various parts of the brain. It can be used to study weaker magnetic fields for the brain.

Positron Emission Tomography. Used to measure metabolic rate, regional blood volume, blood flow, area of abnormalities. Special centers of the brain, like colour processing in visual cortex of humans can be detected by PET.PET uses positron emitting radio isotopes like Carbon eleven.

Computerized Axial Tomography. Uses X- rays to study internal parts in the skull. CAT is now replaced by
CT scanning.

CT Scanning
Uses short X rays for radiographic imaging of internal organs. CT scanning employs more than 30,000, 2-4 mm beams of X-rays. It uses low level X-rays so that radiation damage is little. CT scanning is used to diagnose parts like abdomen, chest, spinal cord, brain, tumors, oedema etc. It is commonly used to investigate the brain after a Stroke.

Magnetic Resonance Imaging. Uses strong magnetic field for generating resonance and low radio
frequency in protons present in the body. The most common proton is the H1 nuclei present in water
molecules. MRI is superior to CT because It uses non ionizing radiations .It gives 2 or 3D pictures.
Image is obtained from any plane. Provides better information about tumors and infections
MRI scanning cannot be performed in patients carrying Ferro magnetic devices like artificial pace makers, metal cardiac valves etc because the MRI magnets will interfere with this. In such a situation CT scanning is recommended.

Also called Echography. It uses ultrasound to produces images of the internal organs. Ultrasound is beyond human hearing power or above 20,000 Hz or 20 kHz. Visual record is called Sonogram or Echogram. Ultra sound is produced through piezoelectric effect. Ultrasound is produced by lead zirconate. Sex determination of Foetus using Sonography is banned in 1994 under prenatal diagnostic act.

Doppler ultrasound Scanning
Used to scan blood flow in vessels, blood clots, and heart abnormalities.

Hall Effect Imaging. Used to pinpoint diseased tissues like cancerous tissue.

Intra Aortic Balloon Pump
Improve blood supply to heart muscles after a clot. It is used to save life in
emergency conditions by restoring the functions of organs. The devices of intra aortic balloon pump are
Implants like artificial heart valve, arteries Disposables like oxygenators, blood bags etc.External prosthetics like artificial foot. It assists heart in pumping of blood.

Used to remove bocks in the coronary artery. A balloon is used to remove the blocks. A contrasting dye is injected to locate the block and then the balloon is inflated to clear the path of blood flow. First coronary angioplasty was done in 1977. Coronary angioplasty is also called as PTCA (Percutaneous Transluminal Coronary Angioplasty) It is also called Baloon Procedure.

Angiography or Arteriography

A radio opaque contrast medium is used for the study of heart walls, valves, atria, ventricles etc.
Artificial Arteries Vascular grafts or arteries made of Dacron (fibrous plastic or terylene ) or Teflon (
Polytetra fluro ethylene). Vascular graft is required in Aneurysm.

Heart Lung bypass Instrument
used during open heart surgery. Roller pump takes the function of heart and Oxygenator takes the function of lung

Blood bag
Used to store blood, separation of components of blood and transfusion of blood.

Instrument used to amplify heart sounds.

Keratoplasy Transplanting of cornea. It is safe because it will not produce immune response due to the lack of blood in the cornea.

Artificial valve Heart valve made up of metal or rubber. Person carrying artificial valve in the heart
should have to take small doses of Anticoagulant daily to preventing clot in the valve.

Used to reduce fibrillation of heart by giving mild electric shock.

Air encephalography
X ray test of the brain parts that contain fluid.

Nuclear Magnetic Resonance is the method used to map internal organs including molecular
structure. It completely avoids the use of ionizing radiations. It uses radio frequency in a controlled
Magnetic field. Resonance of Hydrogen in the water molecule and their energy release is the basis of

Peritoneal dialysis
Used to remove fluid from peritoneum. In peritoneal dialysis, dialysate pass in to
abdominal cavity.


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