Cardiac arrest is the sudden, abrupt loss of heart function. The victim may or may not have diagnosed heart disease. It's also called sudden cardiac arrest or unexpected cardiac arrest. Sudden death (also called sudden cardiac death) occurs within minutes after symptoms appear.

DEFINATION

The most common underlying reason for patients to die suddenly from cardiac arrest is coronary heart disease. Most cardiac arrests that lead to sudden death occur when the electrical impulses in the diseased heart become rapid (ventricular tachycardia) or chaotic (ventricular fibrillation) or both. This irregular heart rhythm (arrhythmia) causes the heart to suddenly stop beating.

Some cardiac arrests are due to extreme slowing of the heart. This is called bradycardia.

Other factors besides heart disease and heart attack can cause cardiac arrest. They include respiratory arrest, electrocution, drowning, choking and trauma. Cardiac arrest can also occur without any known cause.

Brain death and permanent death start to occur in just 4 to 6 minutes after someone experiences cardiac arrest. Cardiac arrest can be reversed if it's treated within a few minutes with an electric shock to the heart to restore a normal heartbeat. This process is called defibrillation. A victim's chances of survival are reduced by 7 to 10 percent with every minute that passes without CPR and defibrillation. Few attempts at resuscitation succeed after 10 minutes.

Early CPR and rapid defibrillation combined with early advanced care can result in high long-term survival rates for witnessed cardiac arrest. For instance, base on statistic, in June 1999, automated external defibrillators (AEDs) were mounted 1 minute apart in plain view at Chicago's O'Hare and Midway airports. In the first 10 months, 14 cardiac arrests occurred, with 12 of the 14 victims in ventricular fibrillation. Nine of the 14 victims (64 percent) were revived with an AED and had no brain damage.

If bystander CPR was initiated more consistently, if AEDs were more widely available, and if every community could achieve a 20 percent cardiac arrest survival rate, an estimated 40,000 more lives could be saved each year. Death from sudden cardiac arrest is not inevitable. If more people react quickly by calling 9-1-1 and performing CPR, more lives can be saved.

The American Heart Association urges the public to be prepared for cardiac emergencies:

Know the warning signs of cardiac arrest. During cardiac arrest a victim loses consciousness, stops normal breathing and loses pulse and blood pressure. Call 9-1-1 immediately to access the emergency medical system if you see any cardiac arrest warning signs. Give cardiopulmonary resuscitation (CPR) to help keep the cardiac arrest victim alive until emergency help arrives. CPR keeps blood and oxygen flowing to the heart and brain until defibrillation can be administered.

Doppler ultrasound is a noninvasive test that can be used to measure your blood flow and blood pressure by bouncing high-frequency sound waves (ultrasound) off red blood cells. A regular ultrasound uses sound waves to produce images, but can't show blood flow.

A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). During a Doppler ultrasound, a technician trained in ultrasound imaging (sonographer) presses a small hand-held device (transducer), about the size of a bar of soap, against your skin over the area of your body being examined, moving from one area to another as necessary. This test may be done as an alternative to more-invasive procedures such as arteriography and venography, which involve injecting dye into the blood vessels so that they shows up clearly on X-ray images.

A Doppler ultrasound may help diagnose many conditions, including:

Blood clots Poorly functioning valves in your leg veins, which can

cause blood or other fluids to pool in your legs (venous insufficiency)

Heart valve defects and congenital heart disease A blocked artery (arterial occlusion) Decreased blood circulation into your legs (peripheral

artery disease) Bulging arteries (aneurysms) Narrowing (stenosis) of an artery, such as those in your

neck (carotid ultrasound) This test may also help your doctor check for injuries to

your arteries or to monitor certain treatments to your veins and arteries

A Holter monitor is a continuous tape recording of a patient's EKG for 24 hours. Since it can be worn during the patient's regular daily activities, it helps the physician correlate symptoms of dizziness, palpitations (a sensation of fast or irregular heart rhythm) or black outs. Since the recording covers 24 hours, on a continuous basis, Holter monitoring is much more likely to detect an abnormal heart rhythm when compared to the EKG which lasts less than a minute. It can also help evaluate the patient's EKG during episodes of chest pain, during which time there may be telltale changes to suggest ischemia (pronounced is-keem-ya) or reduced blood supply to the muscle of the left ventricle.

The only requirement is that the patient wear loose-fitting clothes. Buttons down the front of a shirt or blouse is preferable. This makes it convenient to apply the EKG electrodes, and also comfortably carry the monitor in a relatively discreet manne.

  The chest is cleansed with an alcohol solution to ensure good attachment of the sticky EKG electrodes. Men with hairy chest may require small areas to be shaved. The EKG electrodes (circular white patches on the left) are applied to the chest. Thin wires are then used to connect the electrodes to a small tape recorder. The tape recorder is secured to the patient's belt or it can be slung over the shoulder and neck with the use of a disposable pouch. The recorder is worn for 24 hours and the patient is encouraged to continue his or her daily activities. To avoid getting the setup wet and damaging the recorder, the patient will not be able to shower for the duration of the test.

A diary or log is provided so that the patient can record activity (walking the dog, upset at neighbor, etc.) and symptoms (skipped heartbeats, chest discomfort, dizziness, etc.) together with the time. The Holter monitor has an internal clock which stamp the time on the EKG strips. These can be used to correlate the heart rhythm with symptoms or complaints. After 24 hours, the Holter monitor needs to be returned to the laboratory. This can be removed by the staff. However, if you live out of town or need to take a shower before leaving the house, the monitor can be disconnected from the electrodes and sent back to the laboratory, together with the completed diary.

After returning the Holter Monitor to the doctor's office, satellite clinic or hospital lab, the tape is removed from the recorder and scanned by a technician. Multiple EKG strips are recorded on paper together with a computer-generated summary that provides details about the patient's heart rate and rhythm during the recording. This information is then provided to your doctor.

How long does it take? It takes approximately 10 to 15 minutes to apply the monitor and less than 5 minutes to remove it. The patient will also receive directions. Many monitors are also equipped with an "event" button. Pressing the button during a symptom (dizziness, for example) will help the technician print an ECG from that precise time.

How safe is the test? Holter monitoring is extremely safe and no different than carrying around a small tape recorder for 24 hours. Some patients are sensitive to the electrode adhesive, but no serious allergic reactions are known

The report is provided to the physician, together with multiple EKG strips after the tape has been scanned by the technician. If the technician sees a rhythm that is life-threatening or potentially dangerous the physician is informed immediately. Otherwise, it may take a few days before you get the official results from your physician's office. At that time, you may also receive additional recommendations based upon the results of the test. For example, a pacemaker may be recommended if a patient has blackouts and the Holter monitor shows a seriously slow heart beat during the test.

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