Cardiomyopathy

Heart Disease

Hypertrophic cardiomyopathy

The heart muscle thickens greatly (often asymmetrically) and the muscle cells may become disorganised (which can interfere with the passage of electrical signals through the muscle), without any obvious trigger. In most cases the disease is hereditary, resulting from a gene abnormality. The disease is thought to affect at least 125,000 people in the UK.

In one form of hypertrophic cardiomyopathy (hypertrophic obstructive cardiomyopathy or HOCM) the muscle mass of the left ventricle and the wall that divides it from the right side of the heart (the septum) becomes larger than it should be. This leads to narrowing of the passage through the heart and obstruction of the blood flow out of the heart.

In addition the muscle is stiff and has difficulty relaxing, increasing the amount of pressure required to expand the heart while blood flows in. This reduces the blood holding capacity of the heart.

The altered structure may distort the mitral valve between the chambers of the heart (the left atrium and left ventricle) which may then leak. It’s also known as asymmetric septal hypertrophy (ASH) or idiopathic hypertrophic subaortic stenosis (IHSS).

The condition can be present in the foetus and cause stillbirth, or may develop in infancy. But, more usually, it develops during childhood or early adulthood.

In another form of the disease, non-obstructive hypertrophic cardiomyopathy, the enlarged muscle doesn’t obstruct the blood flow.

The symptoms of hypertrophic cardiomyopathy include shortness of breath on exertion, dizziness, fainting and angina pectoris (angina is chest pain or discomfort caused by reduced blood supply to the heart muscle.) The obstruction to blood flow from the left ventricle increases the ventricle’s work, and a heart murmur may be heard. Some people have cardiac arrhythmias. These are abnormal heart rhythms that in some cases can lead to sudden collapse and death.

Treatment, which includes anti-arrhythmia drugs, aims to control symptoms and prevent complications such as sudden collapse. Surgery may be necessary to remove some of the muscle or repair the mitral valve. A special device called an implanted cardioverter defibrillator (ICD) may need to be put into the heart to deliver and electric shock which will get the heart back into a normal heart rhythm whenever arrhythmias occur, in order to prevent sudden death.

Because there may be a genetic cause, other members of the family should be screened to check for the faulty gene.

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What Is a Pacemaker?

Heart Disease

A pacemaker is a small device that’s placed in the chest or abdomen to help control abnormal heart rhythms. This device uses electrical pulses to prompt the heart to beat at a normal rate.

Pacemakers are used to treat arrhythmias (ah-RITH-me-ahs). Arrhythmias are problems with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

A heartbeat that’s too fast is called tachycardia (TAK-ih-KAR-de-ah). A heartbeat that’s too slow is called bradycardia (bray-de-KAR-de-ah).

During an arrhythmia, the heart may not be able to pump enough blood to the body. This can cause symptoms such as fatigue (tiredness), shortness of breath, or fainting. Severe arrhythmias can damage the body’s vital organs and may even cause loss of consciousness or death.

A pacemaker can relieve some arrhythmia symptoms, such as fatigue and fainting. A pacemaker also can help a person who has abnormal heart rhythms resume a more active lifestyle.

Understanding the Heart’s Electrical System

Your heart has its own internal electrical system that controls the rate and rhythm of your heartbeat. With each heartbeat, an electrical signal spreads from the top of your heart to the bottom. As the signal travels, it causes the heart to contract and pump blood.

Each electrical signal normally begins in a group of cells called the sinus node or sinoatrial (SA) node. As the signal spreads from the top of the heart to the bottom, it coordinates the timing of heart cell activity.

First, the heart’s two upper chambers, the atria (AY-tree-uh), contract. This contraction pumps blood into the heart’s two lower chambers, the ventricles (VEN-trih-kuls). The ventricles then contract and pump blood to the rest of the body. The combined contraction of the atria and ventricles is a heartbeat.

For more information about the heart’s electrical system and detailed animations, go to the Health Topics How the Heart Works article.

Overview

Faulty electrical signaling in the heart causes arrhythmias. Pacemakers use low-energy electrical pulses to overcome this faulty electrical signaling. Pacemakers can:

Speed up a slow heart rhythm.
Help control an abnormal or fast heart rhythm.
Make sure the ventricles contract normally if the atria are quivering instead of beating with a normal rhythm (a condition called atrial fibrillation).
Coordinate electrical signaling between the upper and lower chambers of the heart.
Coordinate electrical signaling between the ventricles. Pacemakers that do this are called cardiac resynchronization therapy (CRT) devices. CRT devices are used to treat heart failure.
Prevent dangerous arrhythmias caused by a disorder called long QT syndrome.
Pacemakers also can monitor and record your heart’s electrical activity and heart rhythm. Newer pacemakers can monitor your blood temperature, breathing rate, and other factors. They also can adjust your heart rate to changes in your activity.

Pacemakers can be temporary or permanent. Temporary pacemakers are used to treat short-term heart problems, such as a slow heartbeat that’s caused by a heart attack, heart surgery, or an overdose of medicine.

Temporary pacemakers also are used during emergencies. They might be used until your doctor can implant a permanent pacemaker or until a temporary condition goes away. If you have a temporary pacemaker, you’ll stay in a hospital as long as the device is in place.

Permanent pacemakers are used to control long-term heart rhythm problems. This article mainly discusses permanent pacemakers, unless stated otherwise.

Doctors also treat arrhythmias with another device called an implantable cardioverter defibrillator (ICD). An ICD is similar to a pacemaker. However, besides using low-energy electrical pulses, an ICD also can use high-energy pulses to treat life-threatening arrhythmias.

Drug treatments

Heart Disease

There are a range of drugs doctors can use to treat heart disease. Many people will find that they’re advised to take several different medicines together, depending on the nature of their heart problem and whether they have risk factors such as high blood pressure.

Many heart drugs have minor side-effects, but most settle down in time. Your doctor and/or pharmacist will alert you to any side-effects and what you should do about them, and you’ll also find details in the information leaflet that comes with your medication. If you develop any unexpected effects, or if you’re worried, contact your doctor.

Aspirin and antiplatelets

These prevent blood clotting in the arteries by reducing the stickiness of blood cells called platelets, which are involved in clotting. This helps to improve blood flow in narrowed coronary arteries and reduces the risk of a blocked artery leading to a heart attack. Aspirin can reduce the risk of dying from a heart attack by 25 per cent or more. These drugs are also used after heart bypass surgery to prevent blood clotting.

Beta blockers

These are used to prevent angina, treat high blood pressure and improve heart failure. They work by blocking the effects of stress hormones, which make your heart beat faster and more forcefully. By slowing the heart and also relaxing the arteries throughout the circulation, the heart doesn’t have to work so hard, which helps in heart failure. Beta blockers also lower the risk of another heart attack if you have already had one, and/or help control abnormal heart rhythms (arrhythmias).

Calcium channel blockers

There are different types of calcium channel blockers and they have differing effects. Some relax and dilate the blood vessels and are used for treating angina, high blood pressure and heart failure, while others slow the rate at which the heart beats and are used to treat abnormal heart rhythms.

Diuretics

These drugs, often referred to as ‘water tablets’, may be used to control blood pressure or remove excess fluid from the body in heart failure. They act by increasing the excretion of water and sodium by the kidneys.

Nitrates

Nitrates dilate the coronary arteries. This improves blood flow to the heart muscle, which helps to relieve angina. Glyceryl trinitrate (GTN) is a commonly used nitrate. It’s in the tiny pills, or spray, that people put under their tongue during an angina attack. Dilation of the arteries reduces the work the heart has to do to pump blood around the body, so nitrates are helpful in heart failure, too.

Statins

These drugs are used to help reduce the amount of cholesterol in the blood. High levels of cholesterol are a risk factor for heart disease. By lowering unhealthy levels of cholesterol, the risk of CHD and heart attacks is reduced.

Thrombolytic drugs

This group of drugs has radically improved the treatment of, and survival from, heart attacks in the past decade. They dissolve clots that form in a coronary artery and trigger heart attacks.

If the drugs are given quickly enough – within a couple of hours of onset of a heart attack – they’ll restore the blood flow through the artery in time to avoid permanent damage to the heart muscle. The earlier this treatment’s given, the better.

However, because the drug thins the blood it can cause brain haemorrhage (stroke) in a significant number of patients