Question: What causes the heart to miss a beat now and then? Is it dangerous?
If a piece of heart muscle is taken from the body and kept alive in a nutrient solution, it will spontaneously contract at about 40 beats per minute.
There is an area near the top of the heart that is made from a complex network of nerves. This is the natural pacemaker of the heart, and it sends electrical signals to the heart muscle to contract at faster rate of approximately 70 beats a minute. This pacemaker is itself controlled by nerves running to the brain, so that anxiety and exercise can cause the heart to beat faster. Certain chemicals in the blood stream can also act on the pacemaker, and the heart muscle itself, to alter the rate at which the heart contracts. It is therefore a very complex process. The occasional dropped (missed) heart beat is due to a blockage of the nerve signal to the heart muscle, a lack of signal from the pacemaker, chemical disturbances in the body and many other factors. Alcohol, smoking, drugs, caffeine, high blood pressure and several diseases can all cause missed heart beats.
If the dropped beats occur only once every minute or so, there is no cause for concern, as this is a common phenomenon, particularly in older people. If you find that every third or fourth beat is being missed, you should be under regular medical care and probably on medication. Patients with problems within these extremes should discuss the matter further with their doctor. S/he will almost certainly perform an ECG (heart electrical test) and probably order blood tests to exclude any serious disease. The treatment will depend on the result of these tests.
Missed heart beats are not in themselves dangerous, unless they become very frequent.

Question: How the blocked arteries are treated by fixing a small balloon in it ?
When an artery becomes narrowed by fatty deposits, insufficient blood may reach the part of the body beyond the narrowing, particularly during exercise, when more of the oxygen carried by the blood, is required as fuel by the muscles. When this happens, pain occurs in the affected muscle. The area affected can be anywhere in the body, but the most commonly involved ate the heart, head and legs. In past years, the only way to overcome this blockage was an operation to bypass the damaged area of artery, or to clean out the fatty deposits from inside the artery. In the last few years, heart surgeons have devised the technique of balloon angioplasty.
In this procedure, a fine tube is threaded into an artery, and moved along it until the blocked area is reached. The tube has a small balloon on the end of it. The hard tip of the tube is pushed through the obstructing fatty deposits, and then the balloon is gently blown up. This pushes aside the fat inside the artery, compresses it, and when the balloon is deflated, a clear channel is left for the blood to pass.
This delicate procedure saves the time, trauma and expense of a major operation, and is being used more and more where the blockage is not extensive. Large blockages will still need surgery, as sometimes the fat is too hard to be pushed away by the balloon.