Text C. Ventricular Tachycardia

Ventricular tachycardia is a ventricular rate of at least 120 beats per minute triggered in the ventri­cles.

Sustained ventricular tachycardia (ventricular tachycardia lasting at least 30 seconds) occurs in various heart diseases that damage the ventri­cles. Most commonly, it occurs weeks or months after a heart attack.

Symptoms and Diagnosis

A person with ventricular tachycardia almost always has palpitations. Sustained ventricular tachycardia can be dangerous and often requires emergency treatment because the ventricles can't fill adequately and pump blood normally. Blood pressure tends to fall, and heart failure fol­lows. Sustained ventricular tachycardia is also dangerous because it can worsen until it becomes ventricular fibrillation—a form of cardiac arrest. Sometimes, ventricular tachycardia causes few symptoms, even at rates of up to 200 beats per minute, but it may still be extremely dangerous.

The diagnosis of ventricular tachycardia is made with an electrocardiogram (ECG).

Treatment

Treatment is given for any episode of ventric­ular tachycardia that causes symptoms and for episodes that last more than 30 seconds even without symptoms. If episodes cause blood pres­sure to fall below normal, cardioversion is needed immediately. Lidocaine or similar drugs are given intravenously to suppress ventricular tachycar­dia. If episodes of ventricular tachycardia persist, a doctor may conduct an electrophysiologic study and try other drugs. The one that works best during electrophysiologic testing can be con­tinued to help prevent recurrences. Sustained ventricular tachycardia is usually triggered by a small abnormal area in the ventricles, and this trigger area can sometimes be removed surgi­cally. In some people with ventricular tachycardia that doesn't respond to drug therapy, a device called an automatic cardioverter-defibrillator may be implanted.

 

Notes:

trigger инициировать, давать начало

recurrence повторение; рецидив

Heart Failure

 

Heart failure (congestive heart failure) is a serious condition in which the quantity of blood pumped by the heart each minute (cardiac output) is insufficient to meet the body's normal requirements for oxygen and nutrients.

Although some people mistakenly believe the term heart failure means the heart has stopped, the term actually refers to the dimin­ished ability of the heart to keep up with its work­load. Heart failure has many causes, including a number of diseases; heart failure is much more common in older people because they are more likely to have the diseases that cause it. Although the condition usually worsens slowly over time, people with heart failure can live for years.

Causes

Any disease that affects the heart and interferes with the circulation can lead to heart failure. Dis­eases may selectively affect the heart muscle, im­pairing its ability to contract and pump blood. By far, the most common of these is coronary artery disease, which limits blood flow to the heart mus­cle and can cause a heart attack. Myocarditis (an infection of heart muscle caused by bacteria, vi­ruses, or other microscopic organisms) may dam­age the heart muscle as may diabetes, an over-active thyroid gland, or extreme obesity. Heart valve disease may obstruct blood flow between heart's chambers or between the heart and the major arteries. Alternatively, a valve that leaks may allow blood to flow backward. These conditions increase the heart muscle's workload, which eventually weakens the force of the heart's contractions. Other diseases primarily affect the heart's electrical conduction system, resulting in slow, fast, or irregular heartbeats that can't pump blood effectively.

If the heart has to work unusually hard over months or years, it gets larger, just as biceps do after months of exercise. At first, this enlargement provides a stronger contraction, but eventually an enlarged heart may result in decreased pump­ing ability and heart failure. High blood pressure (hypertension) can make the heart work harder. The heart also works harder when it has to force the blood through a narrowed exit from the heart, usually a narrowed aortic valve. The resulting condition is similar to the extra burden on a water pump when it's forced to push water through nar­row pipes.

In some people, the pericardium—the thin, transparent covering of the heart—stiffens. This stiffening prevents the heart from fully expanding beats and thus keeps it from filling adequately with blood. Much less often, diseases affecting other parts of the body greatly increase the demand for oxygen and nutrients, so that an otherwise normal heart is unable to meet this increased demand. The result is heart failure.

The causes of heart failure vary around the world because of the different varieties of disease that develop in different countries. For instance, in tropical countries certain parasites can lodge in the heart muscle; this typically causes heart failure at a much younger age than in developed countries.

Symptoms

People with uncompensated heart failure feel tired and weak when performing physical activitiesbecause their muscles aren't getting an adequate amount of blood. The swelling also causes many symptoms. Besides being influenced bygravity, the location and effects of swelling are influenced by which side of the heart is predom­inantly impaired.

Although disease on one side of the heart always causes failure of the whole heart, the symptoms of disease on one side or the other often predominate. Right-sided disease tends to result in a buildup of blood flowing into the right side of the heart. This buildup leads to swelling in the feet, ankles, legs, liver, and abdomen. In contrast, left-sided disease leads to a buildup of fluid in the lungs (pulmonary edema), which causes extreme shortness of breath. At first, it happens during exertion, but as the disease progresses, it also occurs at rest. Sometimes, the shortness ofbreath happens at night while the person is lying down because fluid moves into the lungs. The person often wakes up, gasping for breath of wheezing. Sitting up causes the fluid to drain from the lungs, which makes breathing easier. People with heart failure may have to sleep in a sitting position to avoid this effect. A severe buildup of fluid (acute pulmonary edema) is a life-threaten­ing emergency.

Diagnosis

These symptoms alone are usually enough for a doctor to make a diagnosis of heart failure. The following findings can confirm a doctor's initial diagnosis: a weak and often rapid pulse rate, reduced blood pressure, certain abnormalities in heart sounds, an enlarged heart, swollen neck veins, fluid in the lungs, an enlarged liver, rapid weight gain, and a swollen abdomen or legs. A chest x-ray can show an enlarged heart and fluid accumulated in the lungs.

The heart's performance is often evaluated with further tests, such as echocardiography which uses sound waves to create an image of the heart, and electrocardiography, which examines the electrical activity of the heart. Other tests may be carried out to determine the underlying cause of the heart failure.

Treatment

Much can be done to make physical activity more comfortable, improve the quality of life, and prolong life, but for most people with heart fail­ure, no cure exists. Doctors approach therapy from three angles: treating the underlying cause, removing contributing factors that can worsen heart failure, and treating the heart failure itself.

Treating the Underlying Cause. Surgery can correct a narrowed or leaking heart valve, an abnormal connection between heart chambers, or a blockage of the coronary arteries, all of which may lead to heart failure. Sometimes the cause can be eliminated completely without surgery. For example, antibiotics can cure an in­fection. Drugs, surgery, or radiation therapy can correct an overactive thyroid gland. Similarly, drugs can reduce and control high blood pressure.

Removing Contributing Factors. Smoking, eating salt, being overweight, and drinking alcohol all aggravate heart failure as do extremes of room temperature. Doctors may rec­ommend a program to help a person stop smok­ing, make appropriate dietary changes, stop drinking alcohol, or perform regular, moderate exercise to improve overall fitness. For those with more severe heart failure, bed rest may be pre­scribed as an important part of treatment for a few days.

Excess dietary salt (sodium) can cause fluid retention that counteracts the medical treatment. The amount of sodium in the body usually goesdown if table salt, salt in cooking, and salted foods are limited. People with severe cases of heart fail­ure are usually given detailed information on how to limit salt intake. People with heart failure can check the salt content of packaged foods by reading the labels carefully.

A simple, reliable way to check on the body's retention of fluid is to check body weight daily. Fluctuations of more than 2 pounds per day are almost certainly because of fluid retention. A consistent, rapid weight gain (2 pounds per day) is a clue that the heart failure is getting worse. For this reason, doctors often ask people with heart failure to weigh themselves as accurately as pos­sible every day, typically upon arising in the morning, after urinating, and before eating break­fast. Trends are easier to spot when people use the same scale, wear a similar amount of clothing, and keep a written record of their daily weight.

Treating Heart Failure. The best treatment for heart failure is preven­tion or early reversal of the underlying cause. But even when prevention or early reversal isn't pos­sible, major advances in treatment can prolong life and improve the quality of life for people with heart failure.

Notes:

quantity величина, количество

interfere вмешиваться, мешать; причинять вред

transparent очевидный, ясный, прозрачный

swelling опухание, отёчность

gasp затруднённое дыхание, удушье; дышать с трудом, задыхаться

wheezing хрипение, сопение

obesity ожирение

gain увеличивать, набирать (вес)

scale весы

Cardiomyopathy

 

Cardiomyopathy is a progressive disorder that alters the structure or impairs the function of the muscular wall of the lower chambers of the heart (ventri­cles).

Cardiomyopathy can be caused by many known diseases, or it may have no identifiable cause.