Category Archives: Disorders Of Heart Rhythm
Sinus Node Dysfunction
Sinus node dysfunction or heart pacemaker dysfunction is the malfunctioning of the primary pacemaker of the heart, namely, the sinus node, resulting in abnormal arrhythmias, especially slow heart rate or bradycardia.
- Sinus node dysfunction may be asymptomatic or symptoms such as palpitations, fatigue and weakness may be present.
- Diagnosis by physical examination is confirmed by electrocardiography (ECG).
- Fitting an artificial pacemaker permanently is usually the ideal solution.
When the sinoatrial node or sinus node, which is the pacemaker or the starting point of the electrical activity of the heart, becomes dysfunctional, it may precipitate a constantly low heartbeat called sinus bradycardia. When the sinus node completely stops functioning, it is called sinus arrest.
Usually, when the sinoatrial node is dysfunctional, a new area takes over its function. This substitute pacemaker, which may be a point in the atrium or in the atrioventricular node, is termed an escape pacemaker. The location of the escape pacemaker can be another area much lower in the electric circuit of the heart or even in the ventricles.
Prevalent in the older age group, sinus node dysfunction may result from hypothyroidism or the usage of certain drugs. But more often, a definite cause cannot be identified, in which cases it is termed as sick sinus syndrome. Bradycardia-tachycardia syndrome, in which episodes of tachycardia or fast heart rhythms such as atrial fibrillation and flutter alternates with episodes of bradycardia or slow rhythms, is considered a version of sick sinus syndrome.
Symptoms and Diagnosis
Often, sinus node dysfunction is asymptomatic. General weakness and fatigue may be symptoms of a slow heart rate that persists over a long period. An extremely low heart rate may result in fainting. A fast heart rate is often perceived by the person as Palpitations which are usually felt when the heart rate is high. After a bout of fast arrhythmia, the pacemaker may be delayed in restarting the heart before reverting to normal rhythm. This delay often results in fainting.
Sinus node dysfunction is usually diagnosed from characteristic symptoms such as slow and irregular pulse, a pulse that does not vary even on exertion, or highly fluctuating pulse irrespective of there being no change in activity. Electrocardiography, especially continuous monitoring with a portable Holter monitor helps confirm the diagnosis.
Treatment
An artificial pacemaker, which helps to increase the heart rate, is permanently attached to prevent a slow heart rhythm. If episodes of fast rhythm also occur, Antiarrhythmic drugs that slow the heart are given.
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Bundle Branch Block
Bundle branch block is a complete or incomplete disruption in the electrical conduction system of the heart, involving the right and left bundle branches of the bundle of His which conduct the impulses to the respective ventricles.
The electrical impulses from the atrioventricular node reaches a group of fibers called the bundle of His which divides into the left bundle branch which transmits the impulses to the left ventricle and the right bundle branch which transmits the current to the right ventricle branch two bundle branches. A block in the electrical circuit can occur in the left or right bundle branch.
Symptoms and Diagnosis
Bundle branch block may be asymptomatic and even healthy people may have a block in the right bundle branch which is not usually dangerous except when it is precipitated by heart damage resulting from a heart attack. Block in the left bundle branch is often more serious since it is usually a sign of coronary artery disease resulting from atherosclerosis or uncontrolled high blood pressure, especially in older people.
Electrocardiography (ECG) can diagnose the type of bundle branch block as each type of block produces a unique pattern that can be easily differentiated.
No treatment is needed for either the left bundle branch block or the right bundle branch block, unless there is a perceived risk of a complete heart block. A pacemaker is often implanted in people to initiate the heart rhythm in the event of a complete block which is dangerous.
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Heart Block
Heart block is either a blockage or delay in the electrical conduction system of the heart, as the electrical impulses originating in the sinoatrial node, travels down the atrioventricular node to the ventricles, via the bundle of his and its branches.
- Heart block may be asymptomatic or may cause symptoms such as bouts of fainting, dizzy feeling and general fatigue.
- Heart block can be diagnosed by electrocardiography.
- Artificial pacemaker is required in severe cases.
Heart block is more prevalent in the older age group. According to the severity of the block in the electrical conduction system, heart block is classified as first degree, second degree and third degree blocks.
- In first-degree heart block, which often does not show any symptoms, the electrical impulses starting in the sinus are all conducted to the ventricles but they are delayed a bit longer as it passes the atrioventricular node. Certain conditions such as an overactive vagus nerve which slows down the heart rate, structural defects of the heart, sarcoidosis and rheumatic diseases of the heart may cause a first-degree heart block. Even some drugs such as verapamil, amiodarone, digoxin, diltiazem and beta-blockers that slow down the electrical conduction may also induce it. Though common among youngsters, teenagers, and athletes who are well-trained, due to lack of symptoms, a first-degree heart block is usually diagnosed by an electrocardiography only.
- In second-degree heart block, only a few electrical impulses get transmitted to the ventricles due to which heart beat may become either slow or irregular or sometimes both.
- In third-degree heart block, the pumping capacity of the heart is greatly compromised, making it a very dangerous situation. The electrical impulses that originate in the sinus (sinoatrial node) in the atria fail to reach the ventricles. In the absence of stimulation from the atria, substitute pacemakers such as the atrioventricular node or the bundle of His or in certain cases the ventricles themselves take over but they are slower than the sinoatrial node. Moreover, they may be irregular and undependable. This causes the ventricles to contact irregularly as well as extremely slowly, sometimes at a rate as low as 30 – 40 beats per minute resulting in fainting bouts and dizziness. If the ventricular rate is above 40 beats a minute, the symptoms may not be severe and generally fatigue may be the only symptom. But since the output of the heart is greatly reduced, third-degree heart blocks require urgent medical attention.
Treatment of Heart Block
Treatment varies depending on the degree of heart block, the first-degree block not requiring any special treatment even if a heart disorder is causing it. While a second degree block may necessitate the installation of pacemaker in some cases, a third degree block invariably requires an artificial pacemaker in almost all cases. Heart block in people who suffered a heart attack may be temporary in nature, and may resolve on its own and heart rate may return to normal, but usually, artificial pacemakers are implanted for life.
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What Is Ventricular Fibrillation
Ventricular fibrillation is a life-threatening condition, when extremely fast irregular heart rhythms caused by disturbances in the electrical system of the heart, incapacitates the ventricles from pumping blood.
• Ventricular fibrillation is a potentially fatal situation requiring immediate medical attention.
• The first symptom is unconsciousness, which may culminate in death, if not revived quickly.
• Diagnosis is by electrocardiography which helps find the reason of the cardiac arrest.
• Immediate CPR or cardiopulmonary resuscitation followed by defibrillation may help re-establish the normal rhythm of the heart and prevent death.
In ventricular fibrillation, the ventricles fail to pump blood as they do not contract normally. They just quiver due to a series of uncoordinated impulses stimulating the ventricles. Ventricular fibrillation can be termed cardiac arrest as the heart stops pumping out blood. In the absence or delay of competent medical intervention, it always results in death.
Coronary artery disease, which impedes the supply of blood to the muscles of the heart, is the most commonly diagnosed reason for ventricular fibrillation. It can also result due to certain other conditions which either directly or indirectly affects the heart such as electrical shock, hypoxemia or low level of oxygen in the blood due to drowning, circulatory shock resulting from abnormally low blood pressure or low blood potassium levels (hypokalemia). Certain antiarrhythmic drugs called sodium channel blockers and potassium blockers may cause disturbances in the electrical system of the heart resulting in ventricular fibrillation.
Symptoms and Diagnosis Of Ventricular Fibrillation
The symptoms of Ventricular fibrillation start with sudden unconsciousness, which quickly deteriorates into seizures resulting from lack of oxygen in the brain causing brain damage, which may not be reversible. Without immediate medical intervention, death occurs within minutes.
When a person suddenly falls unconscious or turns pale and collapses, it is usually assumed to be cardiac arrest.
Extremely low blood pressure that is hard to measure by the blood pressure cuff, absence of pulse, undetectable heartbeat, and dilated pupils point to ventricular fibrillation. Electrocardiography can confirm whether the cardiac arrest is due to ventricular fibrillation.
Treatment Of Ventricular Fibrillation
CPR or cardiopulmonary resuscitation must be administered immediately as ventricular fibrillation is an extremely dangerous condition that can be fatal. Electric shock (cardio version) is applied as soon as possible to revive the heart.
When ventricular fibrillation is accompanied by heart failure or shock, the prognosis is not good since 70% of patients die even after resuscitation and cardioversion. Without such additional risk factors, cardioversion, if given immediately, can reverse ventricular fibrillation in 95 out of hundred cases.
To prevent repeated ventricular fibrillation, those who survive an incidence are often fitted with an implantable automatic defibrillator, which will deliver a shock whenever required. If any reversible or treatable condition is the underlying cause of ventricular fibrillation, it is treated and corrected. Drugs to prevent a recurrence are often prescribed, including antiarrhythmic drugs that control abnormal arrhythmias.
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Ventricular Tachycardia Symptoms And Treatment
Ventricular tachycardia is an abnormally fast heart rhythm, of over 120 beats a minute, originating in the ventricles.
- Palpitations or awareness of heart beats is the major symptom.
- Diagnosis is based on electrocardiography (ECG).
- Selective destruction of a specific area of the ventricle responsible for the condition may be necessary, but using an automatic defibrillator is a viable alternative.
Ventricular tachycardia consists of a series of premature ventricular beats closely following one another. It may be sporadic, and after a brief bout of fast, abnormal beats, the normal heart rhythm may be restored. But if the abnormal rhythm persists for more than half a minute, it is termed as sustained ventricular tachycardia. It is prevalent in people whose ventricles are damaged due to some structural disorder of the heart, as well as in those who have had a heart attack recently. Though, generally, the incidence of ventricular tachycardia is more frequent among older people; even young people, even those without any structural heart defect, occasionally develop this condition.
Ventricular Tachycardia Symptoms and Diagnosis
Palpitations or awareness of heartbeat is the main symptom felt by almost everyone with this condition. Sustained ventricular tachycardia often precipitates a dangerous situation of abnormally low blood pressure due to the inability of the ventricles to fill with blood and pump blood adequately, which can lead to heart failure. Sustained ventricular tachycardia may also deteriorate fast to ventricular fibrillation, culminating in cardiac arrest. Occasionally, ventricular tachycardia may be more or less asymptomatic even at the rate of over 200 beats per minute, making it difficult to recognize this dangerous situation.
Ventricular tachycardia symptoms can be diagnosed by electrocardiography (ECG); this can also help assess the need for treatment. A small portable ECG machine called Holter monitor may be kept connected to the patient for a period of 24 hours to measure and record the heart rhythm.
Treatment
Ventricular tachycardia lasting more than half a minute requires medical intervention even when severe symptoms are not present. Sustained ventricular tachycardia is an emergency situation as it often results in blood pressure getting dangerously lowered due to the impaired pumping action of the heart. Immediate cardioversion may prevent a potentially fatal outcome.
Ventricular tachycardia may also be treated with drugs such as lidocaine and amiodarone, given intravenously to suppress the arrhythmia. Procainamide is another useful drug.
Radiofrequency ablation is a minimally invasive surgical procedure by which, selective destruction of a specific area of the ventricle responsible for the ventricular tachycardia, can be achieved. The procedure involves identifying the offending area with the help of ECG, and then applying high frequency energy to kill the tissue, with the help of an electrode-tipped catheter threaded into the heart via a vein. This is preferred to an open-heart surgery due to the lowered risks and reduced hospital stay involved.
Ventricular tachycardia accompanied by other heart disorders, result in poor pumping activity of the heart. To help counteract it, a small device called automatic defibrillator, (similar to an artificial pacemaker) that can detect an arrhythmia and automatically deliver a shock to correct it, is often implanted by a minimally invasive surgery.
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Ventricular Premature Beat (Premature Ventricular Contraction)
A ventricular premature beat, which is also called premature ventricular contraction, is an abnormal but usually harmless extra beat caused by a rogue electrical impulse starting in the ventricles prior to a normal heartbeat.
- Perception of an occasional strong heart beat or of a sporadic skipped beat is the usual symptom.
- Diagnosis is by electrocardiography and further tests may help rule out other heart defects.
- Stressful situations and mild stimulants like coffee and alcohol are better avoided.
More commonly occurring in older people, ventricular premature beat is generally the result of stress, either physical or emotional or it may be triggered by mild stimulants such as alcohol or coffee or by the use of certain drugs like pseudoephedrine contained in anti-allergic medications.
Heart valve disorders that result in enlargement of ventricles, as well as heart failure, may be reason for this condition. Coronary artery disease, soon after a heart attack especially, also may precipitate this arrhythmia.
Symptoms and Diagnosis
Ventricular premature beats are generally asymptomatic except for a feeling of having skipped a heart beat or an extra strong beat. Since they do not affect the pumping mechanism of the heart, they are usually ignored unless very frequent episodes become disconcerting. Though ventricular premature beats are not dangerous in themselves, frequent episodes, especially in people with pre-existing heart defects, they may be precursors of potentially fatal arrhythmias such as ventricular fibrillation and ventricular tachycardia that call for immediate intervention.
Ventricular premature beats can be diagnosed by electrocardiography (ECG) and further tests can rule out any other underlying heart defects.
Treatment
Usually doctors do not prescribe any drugs for people with ventricular beats if they are otherwise healthy, but often advise them to avoid caffeinated beverages and other mild stimulants such as alcohol and anti-allergic medications, in addition to reducing stress.
Beta-blockers are sometimes prescribed to treat the condition if the symptoms cause extreme discomfort or when there is a possibility of developing ventricular fibrillation or tachycardia. But the side effects of these drugs such as drowsiness often discourage people from taking them. However, if people with this condition, have also had heart attacks, the risk of developing fatal arrhythmias like ventricular fibrillation can be greatly reduced by taking beta blockers. Certain structural defects of the heart and certain patterns in which ventricular premature beats occur can predispose a person to developing more serious and often fatal arrhythmias. Bypass surgery or angioplasty to treat coronary artery disease also may reduce the risk of sudden death due to potentially fatal arrhythmias. Antiarrhythmic drugs can also help but they are associated with a greater risk of developing more dangerous arrhythmias, so doctors prescribe them after careful evaluation only.
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Wolff Parkinson White syndrome
Wolff Parkinson White syndrome is a heart disorder resulting from the existence of an abnormal and additional electrical pathway between the atria and the lower chambers (ventricles) of the heart; a congenital condition often causing tachycardia.
- Palpitations, shortness of breath and weakness are the common symptoms.
- Diagnosis can be confirmed by electrocardiography ECG).
- Certain manual procedures help stop the abnormal heart rhythm by stimulating the vagus nerve that is responsible for slowing down the heart rate.
Wolff Parkinson White syndrome is a congenital disorder of the heart characterized by the presence of an abnormal electrical pathway which transmits the electrical impulses from the atria to the ventricles, in addition to the normal route which is through the atrioventricular node. The disorders resulting from this extra connection are collectively termed atrioventricular reciprocating supraventricular tachycardia, and Wolff Parkinson White syndrome is one of the most common causes.
This extra (accessory) pathway predisposes a person to abnormally fast heart rhythms or arrhythmias. Though present at birth, the Wolff Parkinson White syndromemay remain asymptomatic until much later in life. Usually, teenagers and young adults start developing arrhythmias due to this condition but it may start as early as in the first year or even as late as after sixty years of age.
Symptoms
Wolff Parkinson White syndrome is one of the most common heart conditions precipitating the rapid heart rhythm called paroxysmal supraventricular tachycardia, which may become fatal when accompanied by atrial fibrillation.
Listlessness, refusal to eat well, shortness of breath and very fast, outwardly visible, pulsing of the chest are the usual symptoms observed, when arrhythmia due to this syndrome develops in infancy. It can cause heart failure in infants.
In young adults and teenagers, a sudden appearance of palpitations, usually during strenuous exercise is the first symptom of arrhythmia due to WPW. It may subside in a few seconds or may continue for several hours, often causing distress and discomfort. Fainting is also not uncommon.
Shortness of breath, chest pain (angina) and fainting are the usual symptoms of paroxysmal supraventricular tachycardia resulting from WPW, in older people and the symptoms often seem to worsen with age.
Atrial Fibrillation and Wolff Parkinson White Syndrome: If a person with Wolff-Parkinson-White syndrome develops atrial fibrillation, the extra electrical pathway between the atria and the ventricles conducts the abnormally fast electrical impulses much faster to the ventricles than the atrioventricular node, which normally slows down conduction of impulses. This faster transmission may result in a potentially fatal, extremely rapid ventricular rhythm that may lead to ventricular fibrillation which requires immediate medical intervention.
Diagnosis
Since the electrical activity of the heart gets recorded during electrocardiography (ECG), it is the ideal diagnostic test for Wolff-Parkinson-White syndrome which results from the abnormally patterned electrical activity of the heart.
Treatment
The manual stimulation of the vagus nerve through various procedures, if done immediately after the onset of the abnormal rhythm, can often stop the paroxysmal supraventricular tachycardia resulting from Wolff Parkinson White syndrome. When the manual stimulation fails to stop the arrhythmia, intravenous administration of adenosine or verapamil may be given to stop it. To prevent further occurrence, the drugs may be prescribed for continued use.
Digoxin is the drug of choice for children under10 years, but it is contraindicated in adults due to the increased risk of atrial fibrillation precipitating a potentially fatal ventricular fibrillation, due to the action of the drug. Before children with Wolff-Parkinson-White syndrome reach puberty, digoxin is discontinued, as it may enhance the electrical conduction between the atria and the ventricles via the abnormal pathway, increasing the chance of ventricular fibrillation.
A minimally invasive procedure called radiofrequency ablation, for the selective destruction of the extra electrical pathway, is a highly successful solution to the problem and it carries only a minimal risk rate of 0.1%. In this procedure, a catheter fitted with electrodes deliver high frequency energy to the targeted area of the heart, destroying only that area. For young people especially, it is a viable alternative to a lifetime of antiarrhythmic medication.
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Paroxysmal Supraventricular Tachycardia (SVT, PSVT)
Paroxysmal supraventricular tachycardia is an abnormally fast (around 160 to 220 bpm – beats per minute) but regular heart rhythm, that suddenly appears and disappears, and has an abnormal origin in an area other than that in the ventricles.
- Shortness of breath, chest pain (angina) and awareness of heartbeat (palpitations) are the usual symptoms.
- Stimulation of the vagus nerve which has the effect of slowing down the heart rate, help reverse the tachycardia.
- Drugs may be used to stop it.
- Incidence of paroxysmal supraventricular tachycardia, most frequent in the younger age group, is not often as dangerous as it is unpleasant. Strenuous activity and exercise may precipitate it.
Paroxysmal supraventricular tachycardia is the result of the heart getting activated into a rapid heart rhythm, initiated by repeated premature heartbeats of an abnormal nature. Certain abnormalities such as atrioventricular reciprocating supraventricular tachycardia resulting from the presence of an abnormal electrical conduction between the atria and the ventricles or atrioventricular nodal reentrant supraventricular tachycardia resulting from the existence of two different pathways in the atrioventricular node, usually trigger this condition. Occasionally, another abnormality called true paroxysmal atrial tachycardia, due to the generation of abnormally fast or circling impulses in the atria also may precipitate paroxysmal supraventricular tachycardia.
Symptoms and Diagnosis
Uncomfortable palpitations, felt suddenly and then disappearing as suddenly after only a few minutes or even many hours, is the most commonly occurring symptom. Giddiness, shortness of breath, fatigue and chest pain are some of the other common symptoms. Often, no other heart problem is found. Electrocardiogram (ECG) can confirm the diagnosis made from symptoms and physical examination.
Treatment of
The vagus nerve, which has the action of decreasing the heart rate, if stimulated, it can stop paroxysmal supraventricular tachycardia. Taking advantage of this, there are some easy, non-invasive procedures usually performed by qualified medical practitioner or under the supervision of a doctor to reverse this arrhythmia. However, those who have frequent episodes often learn to do them, themselves. Stimulating the carotid sinus on the carotid artery by rubbing or pressing at a point on the neck right below the joint of the jaw, suddenly dipping the face into ice-cold water or straining and applying pressure as if in a hard bowel movement are some such procedures. Initiated soon after the onset of the arrhythmia, these simple procedures are extremely effective.
If the symptoms are very severe and the manual procedures fail to stop the arrhythmia even after 20 minutes, doctors my give an intravenous injection of verapamil or adenosine which can immediately stop it.
In rare cases, applying electric shock to the heart (cardioversion) may be the only option, if drugs are not effective. Treating the condition is easier than prevention, since most antiarrhythmic drugs are effective. Beta-blockers and drugs such as verapamil, diltiazem and digoxin are commonly used. So are flecainide and propafenone.
A minimally invasive procedure called radiofrequency ablation has become very popular in the treatment of arrhythmia. In this procedure, the area from which paroxysmal supraventricular tachycardia is originating, is selectively destroyed by applying high frequency energy, through a catheter fitted with electrodes, that is introduced into the heart through via a vein.
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What Is Atrial Fibrillation And Atrial Flutter (Heart Fluttering)
What Is Atrial Fibrillation?
Atrial fibrillation and atrial flutter are abnormally rapid contractions of the atria resulting from a series of abnormal electrical impulses stimulating it; and on some impulses reach the ventricles, making them contract abnormally fast as well, reducing their efficiency to pump blood.
- Atrial fibrillation and atrial flutter have their origin in disorders that cause the enlargement of atria.
- Depending on the rate of contraction of the ventricles, the symptoms can range from fatigue and chest pain (angina) to palpitations.
- Diagnosis by physical examination can be confirmed by electrocardiography (ECG).
- Drugs that slow down the contractions of ventricles are used to treat this condition. Application of electric shock (cardioversion) can normalize the heart rhythm.
- Incidence of Atrial fibrillation as well as atrial flutter is more frequent in older people.
Atrial fibrillation or flutter is characterized by an abnormally fast contraction of atria, so fast that the walls of the atria seem to be quivering instead of contracting. This affects the proper functioning of the ventricles and impairs the pumping of blood. In atrial fibrillation, the atrial rhythm is not only fast but irregular also. This, in turn, leads to irregular ventricular rhythm. In atrial flutter, the atrial rhythm is still fast but it is regular but the ventricular rhythm may be either regular or irregular. Since the atrioventricular node conducts electrical impulses at a slower rate, all the impulses do not reach the ventricles. Consequently, the ventricles beat at a lower rate than the atria. Even then, the ventricular contractions are still too fast to allow proper filling of the ventricles with blood, impairing the heart’s capacity to pump adequate quantity of blood. This may result in low blood pressure and heart failure.
Causes OF Atrial Fibrillation
Certain diseases that affect the heart, such as coronary heart disease and high blood pressure, can be the cause of the abnormal enlargement of the atria, which in turn predisposes the heart to atrial fibrillation and flutter. Valve defects, precipitated by rheumatic heart disease resulting from an attack of rheumatic fever, congenital defects in the structure and function of the heart, increased heart rate resulting from high levels of thyroid hormones due to hyperthyroidism etc., are other factors favorable to the development of atrial fibrillation and flutter. Excessive alcohol consumption also can be a contributing factor. But sometimes no underlying heart disorder can be identified.
Complications: Since the rapid and incomplete atrial contractions fail to empty all the blood into the ventricles with each beat, blood gets stagnated in the heart, leading to the formation of blood clots. These clots may break free (emboli) and move out of the heart, especially when the arrhythmia is reversed either automatically or through treatment, often leading to blockage in smaller blood vessels. Life threatening situations can result from this, including stroke, if the blockage occurs in an artery in the brain. That is the reason why stroke is found to be the initial symptom of atrial fibrillation and flutter in some cases.
Symptoms and Diagnosis Of A. Fib
Symptoms are usually dependant on the ventricular rate of contraction. A ventricular rate of up to 120 beats/ min. may not precipitate any noticeable symptoms, though rates higher than that may result in discomfort in the chest and severe palpitations.
Both artrial fibrillation and flutter are fast arrhythmias. But the main difference between these two types of arrhythmias is that; in atrial fibrillation, in addition to being fast, the pulse is also irregular, but in atrial flutter, the pulse is fast but regular.
Fatigue, shortness of breath and fainting bouts are symptoms precipitated by the impaired capacity of the heart to pump adequate amount of blood. Older people may experience pain in the chest or develop heart failure. Extremely low blood pressure due to atrial fibrillation or flutter, when combined with other heart disorders, can occasionally result in shock.
Atrial fibrillation or flutter can be diagnosed from symptoms and physical examination but an electrocardiography (ECG) can confirm the condition.
Treatment Of Atrial Fibrillation
Treatment focuses on reducing the rate of contraction of ventricles as well as bringing down abnormally fast heart rhythms to normal level. The disorders of the heart, which are responsible for the development of atrial fibrillation and flutter, are also treated with appropriate drugs. Hyperthyroidism should be treated when present. Surgical intervention to correct valve defects and congenital heart defects also helps. An integral part of the treatment is anticoagulants and blood thinners such as aspirin, in view of the additional risk of blood clot formation in the heart and the potential for stroke.
Slowing the Heart Rate:
- The first line of treatment is with drugs that slow down ventricular contraction, enabling the heart to pump more efficiently.
- In the treatment of atrial fibrillation or flutter, calcium channel blockers like diltiazem are usually tried first.
- Verapamil is a useful drug that can slow down the transfer of electrical impulses from the atria to the ventricles.
- Beta-blockers like atenolol and propranolol may also prove to be useful.
- Digoxin, one of the oldest drugs for heart failure, is the drug of choice for people who have heart failure too, along with the arrhythmia.
Restoring the Rhythm:
Occasionally, atrial fibrillation or flutter may resolve on its own. But more often, medical intervention is necessary to restore normal heart rhythm. Amiodarone and sotalol are two commonly used antiarrhythmic drugs. Other drugs such as flecainide and propafenone are effective as well. But more effective than any antiarrhythmic drug is the active approach: that of converting the arrhythmia to normal rhythm, by the application of shock directly to the heart (cardiversion).
Arrhythmia should be converted to a normal rhythm as early as possible because, once the atria have become enlarged, as it usually happens in about six months from the onset of the disease, it is very difficult to restore normal rhythm. Even when normal rhythm is restored, recurrence rate becomes very high, in spite of taking antiarrhythmic drugs. Also, with the enlargement of the atria, the heart disorder that causes it too becomes worse.
Destroying the Atrioventricular Node
Destruction of the atrioventricular node, which transmits the abnormally patterned electrical impulse to the ventricles, can stop any abnormal impulse from the atria reaching them, thus preventing the ventricles from contracting. A minimally invasive procedure called radiofrequency ablation, in which electrodes fitted at the tip of catheters are guided into the heart for selective destruction of tissue, is employed to destroy the atrioventricular node. Once this node is destroyed, electric impulses from the atria cannot pass into the ventricles. But the drawback is that, it necessitates the use of an artificial pacemaker to stimulate the ventricles. An alternative is pulmonary vein isolation, in which the atrial tissue around the pulmonary vein is destroyed instead, preserving the atrioventricular node. Since this procedure is riskier, with a lower success rate of only 60 to 80 percent, it is rarely used, except in young patients who are free of any other form of heart disorder.
Ablation with radiofrequency can successfully disrupt the abnormal electrical circuit that is causing the atrial flutter, restoring normal rhythm. This minimally invasive procedure has a very high success rate.
Preventing Blood Clots: The risk of blood clots blocking an artery supplying the brain and causing stroke actually increases significantly on reversing atrial fibrillation or flutter and restoring normal rhythm. The reason is that, when the normal rhythm is restored, the pumping action of the heart improves and the existing blood clots inside the heart break free and start travelling through the blood stream. Because of this, almost all people with atrial fibrillation or flutter are given anticoagulants to prevent clots even after the arrhythmia is brought under control, especially those with additional risk factors such as diabetes, old age and high blood pressure. Some structural disorders such as enlargement of the left atrial chamber and disorders of mitral valve pose extra risk. Unless it is an emergency, doctors usually start patients on anticoagulants three weeks prior to a scheduled cardioversion to correct atrial fibrillation or flutter.
However, doctors have to take into consideration the benefits as well as the potential risks involved in anticoagulant use because anticoagulants are contraindicated in patients with bleeding disorders. People with inadequately treated high blood pressure also should avoid these drugs, since they may result in bleeding complications, excessive blood loss during and after surgery or even hemorrhagic stroke.
Once started, anticoagulants are not discontinued even when proper control of the heart rhythm is achieved. This is because the arrhythmia may come back any time, without the person being aware of it, bringing with it the dangers associated with clot formation.
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Atrial Premature Beats (Premature Atrial Contractions)
An atrial premature beat (atrial ectopic beat), is an abnormal extra beat caused due to the stimulation of the atria by a rogue electrical impulse starting from an abnormal site (other than the normal sinoatrial node) prior to a normal heartbeat.
Atrial premature beats are fairly common occurrence in people who are healthy and these extra beats are often quite harmless. People with disorders of the lungs are more prone to this condition, and incidence is more frequent in older people compared to younger people. This condition can be aggravated by mild stimulants like caffeine in beverages and alcohol. Anti- allergic medications often prescribed for cold and allergic rhinitis (hay fever) as well as some drugs taken for asthma also worsen atrial premature beats.
Atrial premature beats are usually asymptomatic but they may be accidentally detected when a person undergoes a physical examination or when an electrocardiography (ECG) is performed. Treatment is possible but generally unnecessary. Antiarrhythmic drugs are used to treat this condition; only if it is very frequent and patient complains of severely distressing palpitations. Otherwise, patients are advised to avoid drugs and other substances that aggravate the symptoms.