Dr. Rajiv Ashok Kabadi, MD

Just as with a standard pacemaker, a biventricular pacemaker consists of a small battery pack and electrical leads, or small wires that conduct electricity to the heart. CRT pacemakers have two or three leads, placed in the upper and lower chambers of the heart. The device measures the contractions of the heart, and if the heart begins to beat out of time it will send small, rhythmic pulses of electricity to resynchronize (hence the name 'cardiac resynchronization therapy) the contractions. This allows the heart to pump blood to the rest of the body more efficiently. Sometimes a CRT is combined with a different kind of device called an implantable cardioverter-defibrillator or ICD, which uses a higher burst of energy to restart the heart if it stops suddenly.

When a biventricular pacemaker is inserted, the wire leads are usually placed via a small incision near the shoulder, then threaded through a vein to the heart. The battery pack is placed under the skin of the chest near the collarbone. Once everything is in place, the leads are connected to the battery, and the CRT can begin helping the heart beat correctly.

It is normal to experience swelling and discomfort as the incisions from surgery heal. It takes time for the heart to adjust to the pacemaker, so vigorous activity should be kept to a minimum for the first few weeks. Strong magnetic fields may affect how the CRT functions, so patients may be advised to avoid them. As patients heart begins to pump blood more effectively, they should soon begin to feel stronger and less fatigued.

• Angina, which is chest pain that occurs when the heart does not receive enough blood flow.
• Heart attack, which happens if the arteries leading to the heart are completely blocked.
• Arrhythmia, or irregular heartbeat, which can develop if the heart does not have enough blood supply.
• Heart failure, which may occur if a heart attack damages the heart and it becomes too weak to pump enough blood to the rest of the body.

Certain factors may increase risk for the disease, like smoking, lack of exercise, being overweight, high cholesterol, high blood pressure, and diabetes. CAD tends to develop over decades, so it can go undetected until it has become quite severe. A diagnosis may be established using such tests as:

• Electrocardiogram (ECG), which records the heart's electrical activity over a period of time. ECGs can detect whether there is enough blood flow to the heart or if a heart attack has occurred.
• Echocardiogram (echo), which creates images of the heart using sound waves. Echos can show whether the heart is able to pump blood normally.
• Stress tests, where an ECG or echo is combined with exercise, like riding a stationary bike or walking on a treadmill. This test is done to find out if the heart can function properly while performing a strenuous activity.

Treatments for the disease include medications such as vasodilators, like nitroglycerin, which dilates (widens) the coronary arteries. CAD may also be treated by a procedure called angioplasty with stent placement, where a balloon is inflated inside a diseased artery to flatten the plaque deposits against the artery walls, creating more room for blood to flow.

In some severe cases of the disease, multiple arteries may be blocked, and an open heart surgery called coronary artery bypass surgery may be necessary. This operation transplants a vessel from another part of the body to form a graft that goes past the narrowed arteries, thus enabling blood to flow around those arteries.

Heart disease is the leading cause of death in the United States for both men and women. This includes coronary artery disease, heart attacks, congestive heart failure, and congenital heart disease. Some conditions, such as genetics, cannot be controlled. But there are many other things one can do to lower their risk for heart disease. Controlling high blood pressure and cholesterol levels, reducing or stopping smoking, exercising more and losing weight if needed, and eating a diet low in sodium can all protect the heart.

Angina is a squeezing type of chest pain that happens when the muscles around the heart don't get enough oxygen. It can be regular or infrequent. Usually, angina is caused by coronary heart disease. However, not all chest pain is angina. Chest pain can also be caused by a lung infection or panic attack, for example, so it is important to have any sudden pain checked.

Arrhythmia is the word for when the heart beats too fast, too slow, or irregularly with skipped beats. It can feel frightening, and depending on the type it can be dangerous, but in most cases arrhythmia is not serious and can be treated. It is very common, especially in older adults.

Heart valve problems can happen in any one of the the heart's four valves that keep blood flowing where it needs to go. Babies can be born with problems in their heart valves, or valves can be damaged by infections. The valves can stiffen and become less mobile, or they can stop closing properly and 'leak' when the heart beats. Valve problems can usually be repaired surgically.