A ventricular pacemaker is a medical device used to help the heart beat normally. In a surgical procedure carried out by cardiology specialists, what is known as the pulse generator of the ventricular pacemaker is implanted in the chest wall, with a wire connected to the muscle in the right lower cardiac chamber, or right ventricle. If the heart beat disappears altogether or becomes too slow, the pacemaker is activated and sends impulses to the right ventricle, causing it to contract and send blood to the lungs. Impulses spread from the right ventricle to the left ventricle and it contracts simultaneously, sending blood around the body.
As the heart has its own pacemaker, which consists of specialized cells that generate impulses and cause the heart chambers to contract, there is only a need for an artificial pacemaker when the natural one is prevented from doing its job. Problems can occur when tissue is damaged following a heart attack, or when a condition called heart block occurs, which stops electrical impulses spreading through the conducting tissue of the heart. Slow or irregular heart beats can result, and a ventricular pacemaker may be required in cases where the conduction between the upper chambers, or atria, and the ventricles, has been lost in a condition known as complete heart block.
The pulse generator in a ventricular pacemaker has a battery which will usually last for up to ten years. While the battery rarely fails unexpectedly, a number of other complications can occur which apply to any permanent pacemaker as well as the ventricular pacemaker. The wire lead can move out of position causing tissue damage, which in extreme cases could perforate the wall of the heart chamber and require surgical treatment. Infections can also occur, and may need antibiotic therapy to resolve.
A particular risk of using a ventricular pacemaker is what is known as pacemaker syndrome, where the atria contract while the valves separating them from the ventricles are shut, so that blood flows the wrong way and the heart output falls, leading to a drop in blood pressure. Dizziness and fainting may occur or, in more severe cases, symptoms of heart failure can be seen with fluid in the lungs and swollen ankles. The condition can often be resolved by reprogramming the ventricular pacemaker, or changing the system to one known as dual-chamber pacing, where leads pass into the right atrium as well as the right ventricle, regulating the contraction of both.
In cases of congestive cardiac failure, where the ventricles fail to beat together, an ordinary ventricular pacemaker may not be enough, and what is called a biventricular pacemaker may be required. Here, leads are positioned inside both ventricles as well as the right atrium. The device is normally given to patients with quite severe heart failure for whom medication is not providing relief, and it has been found to decrease symptoms in around half of all these users.
