List of seven major therapeutic devices of circulatory system:- 1. Prosthetic Cardiac Pacemaker 2. Defibrillator 3. Angioplasty 4. Vascular Grafts 5. Stents 6. Coronary Artery Bypass Grafting 7. Artificial Heart Valve.
Device # 1. Prosthetic Cardiac Pacemaker/Artificial Pacemaker:
When the natural pace maker SA node does not work properly, in such patients normal heart beat can be restored and maintained with an artificial pacemaker.
The artificial pacemaker was introduced by Chardack in 1960. Temporary pace maker is used in emergency such as bradycardia— slow heart beat. Electrodes of temporary pacemaker are introduced from jugular, subclavian and femoral veins as well as from veins of the upper extremity.
Permanent pacemaker is used in atrioventricular (AV) block, SA node dysfunction, etc. The artificial pacemaker consists of a pulse generator containing cell (solid state lithium cell), the lead in the form of a wire and an electrode. During implantation the pulse-generator is placed in a sub-cutaneous pocket.
The lead is inserted into a particular vein which is finally carried to the right ventricle to make contact with the ventricular myocardium. The patients with artificial pacemaker should not go for MRI.
They should avoid powerful radio or radar transmitters. Such patients should not be exposed to airport security metal detectors. Pacemakers are also influenced by cellular phones, by microwave ovens, automobile ignition and electric shavers.
Device # 2. Defibrillator:
Fibrillation is a condition in which the heart muscle is contracting very rapidly but in an uncoordinated fashion. There are atrial and ventricular fibrillation. Artificial fibrillation may occur in myocardial infarction and in rheumatic heart disease.
Ventricular fibrillation is immediately life threating unless it can be stopped by defibrillation. The arrest of cardiac muscle (atrial or ventricular) with restoration of the normal rhythm is called defibrillation. A machine which is used to do defibrillation is called defibrillator.
First Successful Implant of Implantable Cardioverter Defibrillator (ICD) in India:
Dr. K.K. Talwar, a professor of Cardiology of the All India Institute of Medical Sciences (AIIMS), New Delhi, successfully implanted a device to arrest cardiac rhythm disturbances. Dr. Talwar conducted operations on Mrs. Ramwati (35), and Mr. Raj Kumar (56) on 17th April 1995.
This was the first successful implant of implantable cardioverter defibrillator (ICD) in India. The operation was, in fact, the first to be performed in South Asia. The ICD weighs about 129 gm and consists of one or three high voltage electrodes which can be implanted inside the heart or the vein. The ICD itself is implanted under the skin, below the left collar bone.
Device # 3. Angioplasty (Balloon Catheterisation):
Angioplasty (Gr angeion- vessel, plasso- to form) is a technique to remove the atherosclerotic plaques from the coronary arteries through ballooning. Therefore, it is better to call it coronary artery angioplasty. The plaques can block the lumen of the arteries partially or even totally. Therefore, it is essential to clear the passage.
During the procedure, a very small balloon-tipped catheter is inserted into the coronary artery under X-ray observation. Then the balloon is inflated with air to squash the plaques against the blood vessel wall, thereby clearing the lumen of the vessel for blood. It increases the blood flow through the vessel. The patients who undergo the procedure are relieved of coronary ischemic symptoms for at least several years.
Device # 4. Vascular Grafts (Artificial Arteries):
Arteries supply blood to various parts of the body. So any blockade in them would deprive the organ or the tissue to get blood or in other words the oxygen and various nutrients. This requires reconstructive operation which is done by the use of artificial arteries or vascular grafts.
These artificial arteries are made from porous plastic fibres of dacron or teflon. These arteries remain open for many years and function very well. However, artificial arteries are also made from rubber tubes, silver, glass, etc. but they are not good and close very soon. However, long term use of dacron and teflon is not satisfactory for small arteries of less than 6 mm diameter.
Device # 5. Stents:
A special device called a stent, made of stainless steel, resembling a spring coil, can be permanently placed in an artery through a catheter (plastic tube). This is done to ensure proper blood circulation through the of coronary artery that supplies blood to the heart.
Device # 6. Coronary Artery Bypass Grafting (CABG):
It is also called coronary artery bypass surgery. It is normally done when the coronary artery is totally blocked by clot/clots. In this surgery, a blood vessel is taken from another part of the body and is used to bypass the blocked region of the coronary artery.
The saphenous vein (from the leg) and the internal mammary artery (from the chest) are mostly used for this procedure. After this surgery the blood supply to the heart increases.
Device # 7. Artificial Heart Valve:
Artificial heart valves are used to replace the badly damaged, valves and restore an active life style for the patient. Valve replacements are performed all over the world. Artificial heart valves may be either mechanical or made of human or animal tissues.