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Heart Attack and Cardiac Disorders

(35) Heart Attack and Cardiac Disorders

Arrhythmias -- What is an arrhythmia and what treatments does it require?

Mayo Clinic - Heart arrhythmia

National Heart, Lung and Blood Institute - What Is an Arrhythmia?

Medic Scientist

The Organic Diabetic

HACD35

Which arrhythmias are common?

 A variety of common arrhythmias have been identified. Ventricular fibrillation (VF) is the most serious and life-threatening arrhythmia. In VF, the cardiac impulses arising from the ventricles (lower chambers) produce very fast, irregular and chaotic heart rhythm with no pumping action. Most people with VF become unconscious, and emergency treatment (medications, electrical shock, and CPR) must be provided immediately to prevent sudden death.

Premature beats or contractions are the heartbeats that occur earlier than the usual heart cycle and momentarily interrupt your heart’s regular rhythm. Atrial fibrillation (AF) causes your atria (the upper heart chambers) to beat very rapidly and chaotically.

Your ventricles (the lower heart chambers) also beat rapidly at a rate of 120 to 160 beats per minute, which leads to an irregular and rapid heart rhythm. AF is very common among older adults, particularly those with diseased hearts. Atrial flutter also causes your atria to beat very rapidly, and your ventricles also beat rapidly but at a lesser rate (usually 125–175 beats per minute). Atrial flutter is not nearly as common as atrial fibrillation.

Super ventricular tachycardia (SVT) is a fast and regular heart rhythm arising from your atria or AV node. In most cases, SVT begins and ends abruptly. People with Wolff-Parkinson-White (WPW) syndrome are born with an extra electrical pathway (called accessory pathway) between the atria and the ventricles. (This syndrome is named after three physicians who first described it.) In WPW syndrome, this extra pathway allows too many electrical impulses to reach the ventricles. That surplus of impulses can lead to a very rapid heart rhythm-up to 250-300 beats per minute in some cases.

In ventricular tachycardia (VT), the heart impulses arising from the ventricles (lower heart chambers) produce a rapid heart rhythm (160–200 beats per minute).

VT produces a broad (bizarre) QRS complex on an ECG. Ventricular tachycardia often deteriorates to ventricular fibrillation. When heart block (or AV block) occurs, the electrical impulses from the atria (upper chambers of your heart) do not reach the ventricles (or lower chambers). This happens when a block occurs in the electrical conduction system, and it leads to slow heart rhythm. Your doctor would install an artificial pacemaker if such a block persisted or for symptomatic heart block.

Sick sinus syndrome (SSS), a disorder of the sinus node (the natural pacemaker) prevents the sinus node from producing sufficient heart impulses, leading to a slow heart rhythm. An artificial pacemaker is necessary for advanced SSS.

Another syndrome, the long Q-T syndrome, is an inherited medical disorder. It often produces ventricular fibrillation and sudden death. In many cases, doctors treating patients with this syndrome would use certain medications, artificial pacemakers, and electrical shock treatment.

What are common signs and symptoms of arrhythmias?

Although arrhythmias may occur without producing symptoms at all, most people who have arrhythmias experience some symptoms and signs. Those symptoms and signs depend upon the nature and the type of arrhythmia.

Arrhythmias often cause palpitations, skipped heartbeats (premature beats), and a fluttering or pounding sensation in your chest. Then, too, you might feel racing or rapid heartbeats or, conversely, slowing of your heartbeats. Arrhythmias also cause irregular heartbeats.

Arrhythmias have been known to bring on chest discomfort or actual chest pain and shortness of breath (dyspnea). You might develop a periodic cough (usually from premature beats) and feel weak and fatigued. In addition, you might become light-headed or dizzy to the point of nearly fainting (near-syncope) or actually fainting (syncope).With extreme arrhythmias, you would lapse into unconsciousness (usually from ventricular fibrillation) or even die suddenly (from cardiac arrest or ventricular fibrillation).

What are common complications of arrhythmias?

When an arrhythmia is either very rapid or very slow and that pattern continues for a prolonged period, serious complications may occur. For example, if you were a victim of congestive heart failure (CHF), initially your heart would beat very quickly for a prolonged period. If that condition were not treated, your heart’spumping action would become inadequate, causing the CHF. On the other hand, CHF causes a variety of arrhythmias. Thus, the relationship between arrhythmia and CHF is bidirectional (i.e., it works both ways).

In certain arrhythmias, such as atrial fibrillation (AF), small blood clots tend to form in your heart. When these blood clots break loose and travel through your bloodstream to your brain, a stroke usually follows. Your chance of developing a stroke increases when you possess various coronary risk factors, such as high BP.

When a very rapid or very slow heart rhythm significantly reduces blood circulation to your brain, you may develop fainting (syncope) or near-syncope. In a severe case, you would become unconscious. Further, very rapid ventricular tachycardia (rapid and regular rhythm arising from the lower chambers), and particularly ventricular fibrillation, often cause sudden death unless treated promptly.

Sudden cardiac death is very common among heart attack victims.

Terms:

Atrial fibrillation (AF) - chaotic, irregular, and rapid cardiac rhythm arising from the atria.

Supraventricular - any location above the ventricles, namely in the atria or in the A-V node.

Tachyarrhythmia (or tachycardia) - rapid heart rhythm.

Wolff-Parkinson-White (WPW) –syndrome form of congenital anomaly that often causes a very rapid heart rhythm.

Ventricular tachycardia (VT) - regular, rapid cardiac rhythm arising from the ventricles, a serious arrhythmia.

Heart block - slower-than-usual or absent conduction of the cardiac impulse from the atria to the ventricles. Also called AV block.

Sick sinus – syndrome dysfunction of sinus node resulting in abnormally slow heart rhythm and leading to dizziness, near-syncope, or syncope

Long Q-T syndrome - inherited medical disorder that often produces ventricular fibrillation and sudden death.

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(36) Heart Attack and Cardiac Disorders

3D Medical Animation - What is a Heart Attack? (Video)

Signs of heart attack, cardiac arrest and sudden arrhythmia death syndrome (SADS)

Heart attack

What Is a Heart Attack?

HACD36

What tests can detect and diagnose various arrhythmias?

Many tests can detect and diagnose arrhythmias. An electrocardiogram (ECG or EKG) is a recording of the electrical events of your heart through wires and electrodes that doctors attach to the skin of your arms, legs, and chest wall. The ECG device records electrical events by displaying wave forms on a monitor or printing them on paper. Routine ECG tracing records these electrical events for 12 seconds, allowing your doctor to detect and diagnose various arrhythmias. When a routine ECG does not detect a suspected or expected arrhythmia, however, other diagnostic tests may be necessary (discussed shortly).

On the ECG paper, the initial small and round wave, called the P wave, represents the electrical stimulation of the atria. The tallest wave after the P wave is the QRS complex, which represents the stimulation of the ventricles. Another relatively large, triangular wave is the T wave; it represents the period when the ventricles “recharge” their electrical forces to be ready for the next stimulation. These electrical events in total represent one heart cycle, and the normal heart rhythm continues in a healthy heart (called normal sinus rhythm). When something disturbs the normal heart rhythm, various arrhythmias will occur.

An ambulatory ECG (or Holter monitor ECG, named after the scientist who invented it) is a continuous recording of the electrical events of your heart for 24 hours (sometimes up to 48-72) hours). The Holter monitor is small (about the size of a small camera). It’s a portable ECG recorder, worn on a strap over your shoulder or around your waist. Several electrodes are attached to the skin on your chest, and they’re connected by wires to the ECG recorder. You would be instructed to record any signs or symptoms in a diary that would match any such activities.

The Holter monitor ECG records continuously on tape (or on computer chips). When you return the monitor to your doctor’s office or to the heart station of a hospital, a computer plays back and analyzes the tape and prints out the Holter monitor ECG diagnosis so a cardiologist can review it for a final diagnosis.

The event recorder is another form of ambulatory ECG. It’s similar to a Holter monitor ECG in that you would wear it for several days or weeks, but it’s not for continuous recording. When any symptom occurs or when you feel what you think is an arrhythmia, you push a button, and the ECG records for 1 to 2 minutes. The event recorder is most useful for occasional arrhythmias.

When any arrhythmia is considered to occur during physical exertion, a stress test (exercise ECG test) is very valuable. The most commonly used is a treadmill (monitor-driven) stress test. In a stress, or exercise ECG test, you walk on a treadmill (or ride a stationary bicycle) while a machine records an ECG of your heart’s electrical activity. The stress test can reveal any exercise-related arrhythmia that may not be found during a resting ECG.

As described earlier, a stress test is extremely valuable for the evaluation of chest pain, particularly angina, but a stress test should not be performed when an acute heart attack is in progress or is strongly suspected.

The tilt table test is a useful diagnostic tool to evaluate fainting spells (syncope) or near-syncope that may result from certain arrhythmias. In this test, you would lie on a table that can be moved to almost an upright position while a doctor continuously monitors your ECG, BP, and symptoms. Of course, the tilt table test should not be performed when an acute heart attack is in progress.

When the abovementioned tests fail to disclose the necessary diagnostic and therapeutic information, doctors may perform an electrophysiologic study (EPS) to assess the exact nature of a difficult problem. Thus, an EPS is usually recommended for those with life threatening arrhythmias, especially during or soon after an acute heart attack. The EPS is also used to detect and diagnose any suspected arrhythmias that are otherwise not detected.

During the EPS, a doctor inserts a special electrode catheter (a long, thin, flexible wire) into your veins and guides it into your heart. Using such catheters, doctors can identify the exact site causing a life-threatening arrhythmia. Thus, the EPS is very useful not only for the diagnosis of life-threatening arrhythmias but for proper management of a disorder.

Terms:

Ambulatory ECG – test noninvasive diagnostic test that records the electrical activity of the heart for 24 hours using a portable tape recorder to detect any abnormality of heart rhythm (also called a Holter monitor).

Event recorder - form of ambulatory ECG device that records only when an arrhythmia occurs.

Exercise ECG test - noninvasive diagnostic test for coronary artery disease using a motor-driven treadmill, bicycle, or certain chemicals. Also known as a stress test.

Tilt table test - useful diagnostic tool to evaluate fainting spells (syncope or near-syncope).

Electrophysiologic – study insertion of a special electrode catheter into the veins and from there into the heart to identify the exact site causing life-threatening arrhythmias.

What are premature beats?

Premature beats (contractions) are heartbeats that occur earlier than the underlying cardiac cycle and momentarily interrupt your heart rhythm. Premature beats may arise from the atria (then they’re called atrial premature beats) or from the ventricles (in which case they’re called ventricular premature beats). They’re the most common arrhythmias. Premature beats may occur in healthy people, but they occur more frequently in those with various heart diseases. It can be said that almost all adults experience premature beats from time to time. Some people don’t even know it, but most experience some unpleasant feelings, such as “skipped heartbeats” or “funny sensation in the chest.”

By and large, healthy people don’t need active treatment for occasional premature beats other than avoiding possible stimulants, such as caffeine. On the other hand, patients with active heart disease, particularly a heart attack, need active treatment when ventricular premature beats occur very frequently in certain patterns (e.g., multiformed, meaning a different pattern in each premature beat). Under these circumstances, frequent ventricular premature beats may be considered a potential warning sign for more serious arrhythmias, such as ventricular tachycardia or fibrillation.

Almost all adults experience premature beats from time to time.

What is atrial fibrillation?

Atrial fibrillation (AF) occurs when electrical impulses arise from multiple sites in the atria (upper chambers) in a chaotic and uncoordinated fashion. Thus, the atrial wall can’t squeeze the blood down to the ventricles. Only some of the rapid atrial impulses travel down to the ventricles because the atrial impulses must slow down in the AV node, which acts as a “relay station.” The resulting irregular and usually (although not always) rapid heart rhythm is typical of AF.

When AF occurs, like most people you would experience some uncomfortable feelings: fluttering or pounding in your chest, weakness, light-headedness, shortness of breath, and chest discomfort with actual chest pain. The major concern is the increased risk for developing a stroke in people with recurrent or longstanding AF. AF tends to produce blood clots within the heart because of ineffective atrial contraction. Such blood clots may cause a blockage of the arteries in the brain, and that can cause a stroke.

Various medications are available to restore normal heart rhythm or at least to control rapid heart rate brought on by AF. Some people require electrical shock treatment to terminate AF.

Anticoagulants (blood-thinning medications) are recommended for treating patients with recurrent or chronic AF to prevent a potential stroke.

Term:

Anticoagulants - medications that interfere with or prevent blood clot formation

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(38) Heart Attack and Cardiac Disorders

Facts about Sudden Cardiac Arrest (Video)

Cardiac Arrest - American Heart Association - When Minutes Count

CardiacArrest

What is cardiac arrest?

Cardiac arrest is the stopping of any heart pumping action. Naturally, that means that all blood circulation to the entire body stops as well. Cardiac arrest is by no means any particular heart rhythm diagnosis. The underlying arrhythmia that most commonly causes cardiac arrest is ventricular fibrillation, especially in those who experience acute heart attacks. Occasionally, the lack of any electrical activity at all in the heart can cause cardiac arrest. In addition, the disorder may be due to other extremely slow and ineffective heart rhythms.

From a clinical standpoint, cardiac arrest usually occurs together with pulmonary arrest (absence of lung function, which prevents effective breathing). This combination can lead to what you’ve heard described as cardiopulmonary arrest (the absence of both heart and lung function at the same time). As in cases of ventricular fibrillation, emergency treatment for cardiac or cardiopulmonary arrest (e.g., CPR, electrical cardio version, and the like) is essential.

What are the general guidelines for heart attack management?

Patient comment:

When you feel as though you are having a heart attack, you should stop all of physical activity at once and lie or sit down. You or a person nearby-a friend or family member, or even a passing stranger with a cell phone if necessary- should call 911 for immediate medical attention; it is important that you get to the nearest hospital emergency room quickly.

However, you should never drive your own car-that’s far more dangerous than simply waiting for the ambulance, because if you become unconscious, you could wind up in an accident, possibly killing yourself and maybe even someone else. Even when you are not sure whether you are having a heart attack, if you know you have high risk for heart attacks, it’s better to over-diagnose (or overreact) than to respond too late to the real thing. Do not hesitate to call the EMERGENCY even if you wonder whether it is only a false alarm.

Immediate cardiopulmonary resuscitation (CPR) and direct-current shock (defibrillation) are essential for your survival of sudden cardiac death. As soon as a heart attack occurs, either you or your family members or friends should dial the emergency number to request an ambulance. The emergency number dispatcher will contact the emergency medical services (EMS) system. When the emergency number system is not available, you or others should contact the emergency medical response system in the local area. The EMS responders should reach you within 4 to 5 minutes. As time permits, you or others acting for you should also inform your family (private) physician.

If you are conscious, you should chew one regular strength aspirin-chew it, don’t just swallow it, because chewing it will speed up its absorption. Studies have shown that taking aspirin while an acute heart attack is in progress can reduce the death rate by 25%.

Aspirin is effective in inhibiting blood clotting, so taking it improves and maintains blood flow through a narrowed heart artery, which can make the difference between life and death in some patients.

You should stop all physical actions and situate yourself, or have others situate you, in the most comfortable body position (lying or sitting). You could take nitroglycerin (up to three tablets) under your tongue if it has been prescribed before for angina. Do not take someone else’s nitroglycerin on the assumption that it will help-it might make matters worse! If you were found unconscious, as soon as is possible any family member or friend trained in administering CPR-and certainly the responding paramedical personnel-should initiate CPR. As you are being transported by an ambulance to a nearby hospital emergency room (ER), those in the EMS team will provide this emergency treatment as needed until you are stable. They should also give you any available emergency cardiac drugs promptly as needed. And, of course, continuous medical care will be provided in the ER.  Do not try to deny what is happening in such circumstances; avoiding the truth can literally be fatal to heart attack victims. And you should avoid self-diagnosis or self-treatment (this is especially true for someone who might be a physician). It goes without saying that you shouldn’t be driving in this condition; again, don’t try to get yourself to the hospital, call an ambulance instead.

Early diagnosis followed by effective early medical care is extremely important for a better chance of survival and a good outcome. As soon as you are examined in the ER and undergo necessary diagnostic tests, the most important treatment is thrombolytic therapy (the use of special mediations that dissolve blood clots). These agents will reperfuse (i.e., restore circulation) in the damaged heart muscle. .

The management of acute heart attack is carried out primarily by five major modalities as follows:

• Various medications

• Electrical shock treatment (defibrillation) and artificial pacemaker

• Coronary angioplasty (percutaneous transluminal coronary angioplasty or PTCA.

• Coronary artery bypass graft (CABG)

• Cardiopulmonary resuscitation (CPR)

For ventricular fibrillation (chaotic, irregular and ineffective rapid heart rhythm arising from the ventricles), electric shock should be applied immediately using automatic external defibrillators (AEDs). Otherwise, sudden death cannot be prevented in most cases. Most ambulance teams carry portable defibrillators, and many police and fire rescue units are also equipped with defibrillators.

AEDs are very simple to operate and are also available in some commercial airplanes and public places (e.g., large sports fields, music halls, and convention auditoriums). AEDs are often lifesaving devices for heart attack victims before reaching the hospital ER.

If you were experiencing chest pain, the attending physician might administer various commonly used narcotics (painkillers, such as morphine) and would give you oxygen, usually a part of management. In addition, nitroglycerin is often used, because it temporarily opens up narrowed arteries, improving blood flow to your heart muscle.

When the emergency treatment is completed in the ER, those in attendance would transfer you to the coronary (cardiac) care unit (CCU) for further management along with more diagnostic tests.

After they fully evaluated you in the CCU, they would attempt coronary angioplasty (dilatation of narrowed or blocked coronary arteries) after a coronary angiogram.

If you did not respond satisfactorily to coronary angioplasty (another term for percutaneous transluminal coronary angioplasty, or PCTA) or those attending you found it to be technically difficult, they would consider a coronary artery bypass graft (CABG).

Terms:

Cardiopulmonary resuscitation (CPR) - life-saving technique using artificial respiration and cardiac massage to restore normal functions of the heart and lungs after cardiac arrest.

Thrombolytic therapy - intravenous administration of medications that dissolve blood clots blocking the coronary arteries.

Taking aspirin while an acute heart attack is in progress can reduce the death rate by 25%.

Avoiding the truth can literally be fatal to heart attack victims.

What medications are commonly used to treat heart attack victims?

There are many medications used in the treatment of a heart attack, but the most important medications are various thrombolytic agents (medications to dissolve the blood clots in the coronary arteries). Commonly used agents are digoxin (often called heart pill), beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, diuretics (often called water pills), angiotensin II receptor blockers, and spironolactone (Aldacton). The scope of this book does not permit detailed discussion of these medications.

When these medications are not effective, various medical/surgical devices, such as a heart pump (called left ventricular assist devices), a biventricular artificial cardiac pacemaker, and even an artificial heart have been used in the management of advanced CHF. In addition, the treatment of the underlying coronary artery disease such as coronary artery dilatation and coronary artery bypass surgery is very important in the management of CHF. When all of this management is not effective, the transplantation of a new heart must be considered as a last resort in the treatment of far-advanced CHF. When advanced CHF fails to improve in heart attack victims, a fatal outcome is often unavoidable.

An additional medication is found in the common aspirin. Heart attack victims are advised to chew one regular-strength aspirin when first experiencing chest discomfort. Aspirin is effective in inhibiting blood clotting in the coronary arteries. ER personnel often use “super aspirin” (a platelet II-b/III-a receptor blocker) together with a thrombolytic agent. Super aspirin has been found to be more potent than regular aspirin in preventing new blood clot formation. Anticoagulants (blood-thinning drugs), such as heparin or hirudin, often can prevent blood clotting. The relief of chest pain usually requires various narcotics (painkillers), such as morphine. Additionally, doctors commonly use nitroglycerin to relieve chest pain because this drug temporarily opens up narrowed coronary arteries and improves blood flow to the heart muscle.

Various beta-blocking medications are effective in lowering rapid heart rates and blood pressure so that the workload of the damaged heart muscle can be reduced. Anti-arrhythmic agents include various medications (e.g., lidocaine, procainamide, amiodarone) needed to manage and prevent a variety of rapid heart rhythms. Lipid or cholesterol-lowering drugs (e.g., statins, niacin) will reduce blood cholesterol. They’re beneficial if given early after a heart attack for a better chance of survival. The management of various complications requires many other medications (e.g., digoxin, antihypertensive drugs).

Term:

Anti-arrhythmic agents - medications such as quinidine or procainamide (Pronestyl) used for the prevention and treatment of various cardiac arrhythmias.

 

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(37) Heart Attack and Cardiac Disorders

Complete heart block

What Is Heart Block?

HACD37

What is a heart block?

A heart block (atrioventricular or AV block) is an interruption of the heart impulses from the atria (commonly the sinus node) to the ventricles. This interruption results from a conduction block that occurs within the AV node and other conduction pathways (e.g., the His bundle and other branches). Although the conduction interruption can be either partial (incomplete) or complete, discussion deals with complete heart block because of its clinical importance.

In complete heart block, all heart impulses from the atria are blocked, and none of them reach the ventricles. Consequently, a “backup pacemaker” (usually the AV node or the ventricles themselves) stimulates the ventricles. Thus, the heart rhythm in a heart block is very slow and unstable (a rate of 25-40 beats per minute). Heart block often produces various symptoms such as light-headedness, a fainting spell (syncope), and weakness. In addition, heart block may cause CHF or may worsen preexisting CHF. An artificial pacemaker is needed for persisting heart block.

Term:

Complete heart block - disturbance of normal conduction from the atria to the ventricles preventing electrical impulses from traveling through the heart muscle and conduction system, causing a very slow heart rhythm.

What is sick sinus syndrome?

Sick sinus syndrome (SSS) is a disorder in which the sinus node (the natural pacemaker) fails to produce sufficient heart impulses. That failure leads to an unstable and slow heart rhythm. At times, slow heart rhythm may be mixed with rapid heart rhythms (e.g., in AF or ventricular tachycardia). That combination of slow and rapid heart rhythm is called the bradycardia-tachycardia syndrome.

Various symptoms (almost the same as those in a heart block) may be observed in advanced SSS. An artificial pacemaker is needed to treat advanced SSS, and additional medications may be necessary to treat the tachycardia (rapid rhythm) part of this disorder.

What is ventricular tachycardia?

Ventricular tachycardia (VT) is a rapid and regular heart rhythm (140-180 beats per minute) with bizarre (broad) QRS complexes. The impulses arise from the ventricles (lower heart chambers), commonly in an area of the heart muscle damaged by a heart attack. VT may occur suddenly for a short period and may stop without treatment.

However, VT often lasts for a long time, especially in the setting of an acute heart attack. It may deteriorate into a more serious arrhythmia: ventricular fibrillation. VT may cause a variety of symptoms, such as light-headedness (near-syncope), fainting (syncope), shortness of breath, weakness, chest pain, and a feeling of impending death.

A physician would use various medications (e.g., lidocaine, amiodarone, procainamide, and the like) to treat and prevent VT. In some cases, when drug management is not effective, a physician might resort to the use of electrical shock treatment (direct-current shock).

When VT persists or recurs, an electro physiologic study can determine the  exact nature of VT, and then the physician can arrange for more effective management. Selected cases may require an implantable cardioverter-defibrillator to control recurrent and serious VT.

Term:

Direct-current shock - electric shock for rapid heart rhythm.

What is ventricular fibrillation?

Ventricular fibrillation is an uncoordinated, irregular, and very rapid heart rhythm arising from multiple sites within the ventricles. VF is the most serious and life threatening arrhythmia because it prevents any pumping action. Consequently, it stops any blood circulation in your entire body, and you lose consciousness instantly. Death follows within a few minutes unless emergency treatment restores your normal heart rhythm. Such emergency treatment can include CPR, electrical cardiac defibrillation, and the like.

When emergency treatment is delayed for more than 4 minutes, damage to the brain may become permanent, even if a stable heart rhythm is restored later. Thus, immediate emergency treatment for VF is essential.

Term:

Implantable cardioverter-defibrillator (ICD) - small electronic device implanted in the chest to deliver an electrical shock automatically when ventricular fibrillation or tachycardia develops.

 

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(39) Heart Attack and Cardiac Disorders

What is ANGIOPLASTY and STENTING?

Heart Disease Treatment With Angioplasty and Stents

HACD39

What is thrombolytic therapy and when is it used?

 Patient comment:

When you suffer from a heart attack, the most important medication is thrombolytic agent (a drug to dissolve blood clots blocking your heart arteries). This thrombolytic agent is most effective when given within 30 minutes to 3 hours after the onset of a heart attack. That’s why you should not delay seeking medical attention as soon as you feel like you are having a heart attack. If the agent is given more than 24 hours after the beginning of the symptoms, it does you almost no good at all.

Thrombolytic therapy is the intravenous administration of medications that dissolve blood clots blocking your coronary arteries. The thrombolytic agents are often called clot busters. The earlier you receive a thrombolytic agent after a heart attack, the greater your chance of survival. That’s because reducing the damage of your heart muscle leads to improved pumping action.

Thus, thrombolytic therapy is a mainstay in the early management of heart attack at the present time. For best therapeutic results, the thrombolytic agent must be administered within 30 minutes to 3 hours after the onset of symptoms. Giving the agent later than 3 hours reduces the beneficial effects of thrombolytic therapy. Delaying such treatment for 12 to 24 hours drastically reduces the therapy’s beneficial effects.

In addition, if the agent is administered after more than 24 hours from the onset of symptoms, thrombolytic therapy produces little or no beneficial effect.

At present, the most important and standard thrombolytic drug is tPA or alteplase (Activase) in the United States. The next most commonly used thrombolytic agents are retoplase (Retavase), urokinase (Abbokinase), and finally streptokinase (Kabikinase, Streptase). In addition, other thrombolytic agents may include lanoteplase, anistreplase, and tenectoplase (the newest drug).

A thrombolytic drug, most commonly alteplase, is given intravenously with an anticoagulant agent (e.g., heparin). Heparin and aspirin are unable to destroy existing blood clots, but they can prevent blood clots from reforming after they are broken up.

Certain limitations govern who the best candidates are for thrombolytic therapy. For example, you would have had to experience symptoms of acute heart attack within 3 hours after their onset (within 12 hours at most). Also, if you are an adult younger than 75 years and have an S-T segment elevation on an ECG, you are considered a good candidate. If as a heart attack victim you had a systolic BP of less than 180 mm Hg, any heart rate, and diabetes, you would qualify.

In some clinical circumstances, your doctor would avoid thrombolytic therapy or use it with great caution. If you were older than 75 years, you’d be at a higher risk, even if you were otherwise in good general health. Then, too, such therapy would not be used if your heart attack symptoms had continued for more than 12 hours. The same precaution would apply to you if you were pregnant. Your doctor might hesitate to use thrombolytic therapy, or use it cautiously, if your ECG demonstrated no S-T segment elevation, even if the diagnosis of a new heart attack were certain.

Others who would prompt caution are those with recent trauma (especially head injury) or surgery, heart attack victims recovered from prolonged CPR, and those with active peptic ulcers.

Thrombolytic therapy would not be used at all in treating those with recent major bleeding from any organ or for those whose ECG demonstrated a depressed S-T segment, such as seen in a non-Q wave heart attack. Doctors would avoid using such therapy also for treating people with a history of stroke, particularly cerebral hemorrhage, and those with uncontrolled and extremely elevated high BP.

As long as the above-mentioned conditions are not present, thrombolytic therapy should be considered as the first-line lifesaving measure for any heart attack victim, regardless of age or gender.

Terms:

Clot busters - another term for thrombolytic agents, medications that dissolve blood clots.

Cerebral hemorrhage - a form of stroke with hemorrhage (bleeding) in the brain.

The earlier you receive a thrombolytic agent after a heart attack, the greater is your chance of survival.

Does thrombolytic therapy produce complications?

Fortunately, complications and side effects from thrombolytic therapy are rare. Hemorrhagic stroke (cerebral hemorrhage) is the most serious complication of thrombolytic therapy, and it usually occurs during the first day after the administration of the agent. The chances of this occurring are reported to be 0.5 to 0.1%. In addition, internal bleeding may occur in other organs, such as the intestines, stomach, and urinary tracts. Other side effects may be allergic reactions to the agents, hypotension (low BP), and cholesterol embolization.

Streptokinase (one of the thrombolytic agents) given without heparin is reported to show the lowest risk of complication. However, its effectiveness in restoring blood flow is less than that of other thrombolytic agents. The mortality (death) rate from bleeding is reported to be 3 in every 1,000 patients treated with thrombolytic therapy, but its survival benefits, particularly in combination with aspirin, last for many years.

Other aspects of managing a heart attack include percutaneous transluminal coronary angioplasty (PTCA), coronary artery bypass graft (CABG), an artificial pacemaker, electric shock treatment, and cardiopulmonary resuscitation (CPR). Another new device called an atherectomy catheter can shave off and remove plaque from the inside of the diseased coronary artery. A new device called a laser-tipped catheter can vaporize the blockage of the diseased coronary artery with a tiny laser beam. This new device may be useful when the blocked or narrowed segment of the diseased coronary artery is long, and the ordinary PTCA is technically difficult to perform.

Term:

Cholesterol embolization - cholesterol clot formation in the bloodstream

What is coronary angioplasty, and who needs it?

Coronary angioplasty (an abbreviated term for percutaneous transluminal coronary angioplasty or PTCA) is one of two standard revascularization procedures to open up the narrowed (stenotic) or blocked coronary arteries. Emergency coronary angioplasty is the more commonly performed procedure for practically all heart attack patients. Coronary angioplasty is most successful when performed within 12 hours after the onset of symptoms, and the sooner the better. A cardiac surgical team must be available immediately in case the PTCA is unsuccessful and produces major complications.

After injecting a local anesthetic into the groin (less frequently in the arm), doctors place a narrow tube (catheter) containing a fiber optic camera and direct it to the narrowed or blocked coronary artery. Then they pass a tiny deflated balloon through the catheter to the narrowed or blocked coronary artery as they watch an x-ray image on a TV screen. They advance the guide catheter in the diseased coronary artery until it arrives at the blockage. At that point, they inject a small amount of contrast material through the catheter, watching the procedure on the screen, to determine the exact location of the blockage or narrowing of the coronary artery.

They then inflate the small balloon to squeeze the plaque against the walls of the coronary artery. That action flattens out the plaque and opens up the narrowed artery so that it will be able to restore blood circulation.

The doctors inflate the balloon for perhaps 30 to 120 seconds and then deflate it. Chest pain often occurs when the balloon is inflated because the blood flow is temporarily interrupted by the balloon in the segment of the heart muscle. Medical staff should be informed as soon as a brief chest pain occurs. They inflate and deflate the balloon several times thereafter.

Doctors sometimes use a relatively new device called a coronary stent, an expandable metal mesh tube. They commonly implant the stent during PTCA-about 80% of angioplasty procedures-at the site of the blockage to prevent restenosis of the coronary artery.

When the PTCA is considered to be successful, doctors remove the balloon catheter and perform a coronary angiogram (visualization of coronary arteries by movie camera) to assess the improved coronary blood circulation.

Then they remove the guide catheter. Most patients are able to go home by 1 to 2 days after the procedure.

Terms:

Transluminal coronary angioplasty (PTCA) - standard revascularization procedure to open up narrowed or blocked coronary arteries.

Coronary stent - expandable metal mesh tube used in PTCA to prevent restenosis of the coronary artery.

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