Atrial fibrillation (AF) is a supraventricular tachyarrhythmia characterized by disorganized atrial electrical activity and progressive deterioration of atrial electromechanical function. Electrocardiographic manifestations of atrial fibrillation include absence of P waves; rapid oscillations (or fibrillatory [f] waves) that vary in amplitude, frequency, and shape; and an irregular ventricular response.
Atrial fibrillation is the most common arrhythmia encountered in clinical practice (see Media file 1) and is a significant public health problem in the United States. Atrial fibrillation affects more than 2.2 million Americans and almost 5% of the population older than 69 years. The prevalence of atrial fibrillation increases dramatically with age. Atrial fibrillation is associated with known cardiovascular risk factors such as hypertension, coronary artery and valvular heart disease, heart failure (HF) and diabetes mellitus.1
Data from the Framingham heart study show that atrial fibrillation is associated with a 1.5- to 1.9-fold higher risk of death, which is in part due to the strong association between atrial fibrillation and thromboembolic events.2 While patients can be asymptomatic, many experience a wide variety of symptoms, including palpitations, dyspnea, fatigue, dizziness, angina, and decompensated heart failure. In addition, atrial fibrillation can be associated with hemodynamic dysfunction, tachycardia-induced cardiomyopathy, and systemic thromboembolism.
Overall, approximately 15-25% of all strokes in the United States (75,000/y) can be attributed to atrial fibrillation. Known risk factors for stroke in patients with atrial fibrillation include male sex, valvular heart disease (rheumatic valvular disease), heart failure, hypertension, and diabetes. Additional risk factors, such as advanced age and prior history of stroke, diabetes, and hypertension, place patients with preexisting atrial fibrillation at even higher risk for further comorbidities such as stroke(see Table 1)
Table 1. Risk Factors for Stroke in Patients with Nonvalvular Atrial Fibrillation
Risk Factors Relative Risk
Prior stroke or TIA 2.5
History of hypertension 1.6
Heart failure and/or reduced left ventricular function 1.4
Advanced age 1.4
Coronary artery disease 1.5
Patients with rheumatic heart disease and atrial fibrillation have an even higher risk for stroke (17-fold). At least 4 large clinical trials have clearly demonstrated that anticoagulation with warfarin decreases the risk of stroke by 50-80%.
Unlike most cardiovascular diseases, the prevalence of atrial fibrillation is increasing in the United States and worldwide. Atrial fibrillation is frequently encountered in both the inpatient and outpatient settings. Primary therapeutic goals include rate control, maintenance of sinus rhythm, and prevention of thromboembolism.
While the precise mechanisms that cause atrial fibrillation are incompletely understood, atrial fibrillation appears to require both an initiating event and a permissive atrial substrate. Significant discoveries in the last decade have highlighted the importance of focal pulmonary vein triggers, but alternative and nonmutually exclusive mechanisms have also been evaluated. These include multiple wavelets, mother waves, fixed or moving rotors, and macro-reentrant circuits. In a given patient, multiple mechanisms may be present at any given time. The automatic focus theory and the multiple wavelet hypothesis appear to have the best supportive data.
A focal origin of atrial fibrillation is supported by several experimental models showing that atrial fibrillation persists only in isolated regions of atrial myocardium. This theory has garnered considerable attention recently as studies have demonstrated that a focal source of atrial fibrillation can be identified in humans and that isolation of this source can eliminate atrial fibrillation.
The pulmonary veins appear to be the most frequent source of these automatic foci, but other foci have been demonstrated in several areas throughout the atria. Cardiac muscle in the pulmonary veins appears to have active electrical properties similar, but not identical, to those of atrial myocytes. Heterogeneity of electrical conduction around the pulmonary veins is theorized to promote reentry and sustained atrial fibrillation. Thus, pulmonary vein automatic triggers may provide the initiating event and heterogeneity of conduction may provide the sustaining event in many patients with atrial fibrillation.
The multiple wavelet hypothesis proposes that fractionation of wavefronts propagating through the atria results in self-perpetuating “daughter wavelets.” In this model, the number of wavelets is determined by the refractory period, conduction velocity, and mass of atrial tissue. In this model, increased atrial mass, shortened atrial refractory period, and delayed intra-atrial conduction increase the number of wavelets and promote sustained atrial fibrillation. This model is supported by data from patients with paroxysmal atrial fibrillation demonstrating that widespread distribution of abnormal atrial electrograms predicts progression to persistent atrial fibrillation.4 Intra-atrial conduction prolongation has also been shown to predict recurrence of atrial fibrillation.5 Together, these data highlight the importance of atrial structural and electrical remodeling in the maintenance of atrial fibrillation.
Atrial fibrillation shares strong epidemiologic associations with other cardiovascular diseases such as heart failure, coronary artery disease, valvular heart disease, diabetes mellitus and hypertension.1 These factors have been termed upstream risk factors, but the relationship between comorbid cardiovascular disease and atrial fibrillation is incompletely understood and more complex than this terminology implies. The exact mechanisms via which cardiovascular risk factors predispose to atrial fibrillation are not fully understood but are under intense investigation. Catecholamine excess, hemodynamic stress, atrial ischemia, atrial inflammation, metabolic stress, and neurohumoral cascade activation are all purported to promote atrial fibrillation.
Atrial fibrillation affects more than 2.2 million Americans. One in 4 individuals 40 years of age and older will develop atrial fibrillation during their lifetime.6 Atrial fibrillation can occur in the absence of comorbidities, as it does in 10-15% of cases of atrial fibrillation (lone atrial fibrillation). However, atrial fibrillation is often associated with other cardiovascular diseases, including hypertension; heart failure; diabetes; ischemic heart disease; and valvular, dilated, hypertrophic, restrictive, and congenital cardiomyopathies.6
Atrial fibrillation can be triggered after cardiac surgery and is associated with pulmonary disease, thyrotoxicosis, acute ethanol intoxication, and electrolyte imbalance. Given the almost epidemic proportions of patients with atrial fibrillation, clinicians should be aware of the multiple mechanisms and triggers for atrial fibrillation. Correcting the underlying disorder is often necessary to successfully treat atrial fibrillation.
Atrial fibrillation is associated with increased morbidity and mortality, in part due to the risk of thromboembolic disease in atrial fibrillation and in part due to its associated risk factors. Disruption of normal atrial electromechanical function in atrial fibrillation leads to blood stasis. This, in turn, can lead to development of thrombus, most commonly in the left atrial appendage. Dislodgement of a clot can lead to embolic phenomena, including stroke.
One of the major management decisions in atrial fibrillation (and atrial flutter) is determining the risk of stroke and appropriate anticoagulation regimen for low-, intermediate-, and high-risk patients. For each anticoagulant, the benefit in terms of stroke reduction must be weighed against the risk of serious bleeding.
Most clinicians agree that the risk-benefit ratio of warfarin therapy in low-risk patients with atrial fibrillation is not advantageous. Warfarin therapy has, however, been shown to be beneficial in higher-risk patients with atrial fibrillation. A target international normalized ratio (INR) of 2-3 is traditionally used in this cohort as this limits the risk of hemorrhage while providing protection against thrombus formation.
The appropriate treatment regimen for patients with atrial fibrillation at intermediate risk is controversial. In this population, the clinician should assess risk factors for thromboembolic disease, patient preference, risk of bleeding, risk of falls or trauma, and likelihood of medication adherence. Warfarin is also superior to clopidogrel or a combination of clopidogrel and aspirin in the prevention of embolic events in higher-risk patients. A new class of oral direct thrombin inhibitors are in the late stages of clinical trial or pending approval and may be as effective and as safe as warfarin in higher-risk nonvalvular atrial fibrillation.
Several risk factor assessment algorithms have been developed to aid the clinician in decision-making regarding anticoagulation in atrial fibrillation. The CHADS2 index7 (Cardiac failure, Diabetes, Stroke [or S2 = TIA]) is the most widely used of these algorithms. The CHADS2 index uses a point system to determine yearly thromboembolic risk. Two points are assigned for a history of stroke or TIA, and one point is given for age over 75 or a history of hypertension, diabetes, or heart failure. The predictive value of this scoring system was evaluated in 1733 elderly patients with nonvalvular atrial fibrillation aged 65-95 who were not given warfarin at hospital discharge. Although high scores were associated with an increased rate of stroke, few patients had a score greater than 5 or a score of 0 (see Table 2).
Table 2. Adjusted Stroke Rate in Patients with Nonvalvular Atrial Fibrillation not Treated with Anticoagulation
Open table in new windowCHADS2 Score Adjusted Stroke Rate (%/y)
Recommendations for anticoagulation for patients with nonvalvular atrial fibrillation are based on 2006 ACC/AHA/ESC task force guidelines on the management of patients with atrial fibrillation8 (see Table 3).
Table 3. Recommendations for Antithrombotic Therapy in Patients with Nonvalvular Atrial Fibrillation
Open table in new windowRisk Category Recommended Therapy
No risk factors Aspirin 81-325 mg daily
One moderate-risk factor Aspirin 81-325 mg daily or warfarin (INR 2-3)
Any high-risk factor or more than 1 moderate-risk factor Warfarin (INR 2-3)
High-risk factors include prior stroke, TIA, and systemic thromboembolism.
Moderate-risk factors include age older than 75 years, hypertension, heart failure, left ventricular function <35%, and diabetes mellitus.
Risk factors of unknown significance include female gender, age 65-74 years, coronary artery disease, and thyrotoxicosis.
Atrial fibrillation is strongly age-dependent, affecting 4% of individuals older than 60 years and 8% of persons older than 80 years. The rate of ischemic stroke among elderly patients not treated with warfarin averages approximately 5% per year.
Initial evaluation of the patient with new-onset atrial fibrillation should focus on the patient's hemodynamic stability. An effort should also be made to evaluate for potential comorbid diseases that contribute to initiation or maintenance of atrial fibrillation. Immediate electrical cardioversion should be considered for patients with hemodynamic collapse or evidence of cardiac ischemia.
Clinical type of atrial fibrillation should be documented (paroxysmal, persistent, or permanent)
Type, duration, and frequency of symptoms should be assessed
Precipitating factors should be assessed (ie, exertion, sleep, caffeine, alcohol use)
Modes of termination should be assessed (ie, vagal maneuvers)
Prior antiarrhythmics and rate-controlling agents used should be documented
Presence of underlying heart disease should be assessed
Any previous surgical or percutaneous atrial fibrillation ablation procedures should be documented
The physical examination is helpful in determining underlying causes and sequelae of atrial fibrillation. An initial examination of the patient with new-onset atrial fibrillation should attend particularly to their hemodynamic stability.
Vital signs: Heart rate, blood pressure, respiratory rate, and oxygen saturation are particularly important in evaluating hemodynamic stability and adequacy of rate control in atrial fibrillation.
Head and neck: May reveal exophthalmos, thyromegaly, elevated jugular venous pressures, or cyanosis. Carotid artery bruits suggest peripheral arterial disease and increase the likelihood of comorbid CAD.
Pulmonary: May reveal evidence of heart failure (ie, rales or pleural effusion). Wheezes or diminished breath sounds are suggestive of underlying pulmonary disease (ie, chronic obstructive pulmonary disease or asthma).
Cardiac: The cardiac examination is central to the physical examination of the patient with atrial fibrillation. A displaced point of maximal impulse or S3 suggest ventricular enlargement and elevated left ventricular pressure. A prominent P2 points to the presence of pulmonary hypertension. Thorough palpation and auscultation are necessary to evaluate for valvular heart disease or cardiomyopathy.
Abdomen: Ascites, hepatomegaly or hepatic capsular tenderness suggest right ventricular failure or intrinsic liver disease.
Lower extremities: Examination of the lower extremities may reveal cyanosis, clubbing or edema. Assessment of peripheral pulses may lead to the diagnosis of peripheral arterial disease or diminished cardiac output.
Neurologic: Evidence of prior stroke and increased reflexes is suggestive of hyperthyroidism.
Atrial fibrillation is strongly associated with established cardiovascular risk factors and advancing age. Hypertension, diabetes, and coronary artery disease promote atrial fibrillation. Structural heart disease, including valvular and congenital heart disease, is also associated with atrial fibrillation. Acute pulmonary processes, acute or chronic alcohol use (ie, holiday or Saturday night heart, also known as alcohol-related cardiomyopathy), illicit drug use (ie, stimulants, methamphetamines, cocaine) and hyperthyroidism also increase the risk of atrial fibrillation. Patients undergoing cardiothoracic or esophageal surgery are another population at risk for atrial fibrillation. In all, 20-40% of these patients experience postoperative atrial fibrillation. Certain poorly defined genetic factors may also contribute to an individual's propensity to develop atrial fibrillation.
Hemodynamic stress: Increased intra-atrial pressure results in atrial electrical and structural remodeling and predisposes to atrial fibrillation. Mitral or tricuspid valve disease and left ventricular dysfunction are the most common causes of increased atrial pressure. Systemic or pulmonary hypertension also commonly predispose to atrial pressure overload. Intracardiac tumors or thrombi are rare causes of increased atrial pressure.
Atrial ischemia: Coronary artery disease can infrequently lead directly to atrial ischemia and atrial fibrillation. More commonly, severe ventricular ischemia leads to increased intra-atrial pressure and atrial fibrillation.
Inflammation: Myocarditis and pericarditis may be idiopathic or may occur in association with the following:
Collagen vascular diseases
Viral or bacterial infections
Cardiac, esophageal, or thoracic surgery
Drug use: Stimulants, alcohol, and cocaine can trigger atrial fibrillation.
Endocrine disorders: Hyperthyroidism and pheochromocytoma have been associated with atrial fibrillation.
Neurologic: Intracranial processes such as subarachnoid hemorrhage or stroke can also precipitate atrial fibrillation.
Familial atrial fibrillation: History of parental atrial fibrillation appears to confer increased likelihood of atrial fibrillation (and occasional family pedigrees of atrial fibrillation are associated with defined ion channel abnormalities, especially sodium channels).9
Abu Zubair meriwayatkan dari Jabir bin Abdullah bahwa Nabi Muhammad SAW bersabda:
"Setiap penyakit ada obatnya. Jika obat yang tepat diberikan dengan izin Allah, penyakit itu akan sembuh".
(HR. Muslim, Ahmad dan Hakim).
Sabtu, 28 November 2009
Diposkan oleh FX di 04.52
The Holy Al-Qur'an (English version)
- Surah 1 - Al Fatiha THE OPENING
- Surah 2 - Al Baqarah THE HEIFER
- Surah 3 - Ali 'Imran - THE FAMILY OF 'IMRAN
- Surah 4 - Al-Nisa' THE WOMEN
- Surah 5 - Al Ma'idah THE REPAST
- Surah 6 - Al An'am THE CATTLE
- Surah 7 - Al A'raf THE HEIGHTS
- Surah 8 - Al Anfal THE SPOILS OF WAR
- Surah 9 - Al Tawbah THE REPENTANCE
- Surah 10 - Yunus JONAH
- Surah 11 - Hud THE PROPHET HUD
- Surah 12 - Yusuf JOSEPH
- Surah 13 - Al Ra'd THE THUNDER
- Surah 14 - Ibrahim ABRAHAM
- Surah 15 - Al Hijr THE ROCKY TRACT
- Surah 16 - Al Nahl BEES
- Surah 17 - Al Isra' THE NIGHT JOURNEY
- Surah 18 - Al Kahf THE CAVE
- Surah 19 - Maryam MARY
- Surah 20 - TA HA
- Surah 21 - Al Anbiya THE PROPHETS
- Surah 22 - Al Hajj THE PILGRIMAGE
- Surah 23 - Al Mu'minun THE BELIEVERS
- Surah 24 - Al Nur THE LIGHT
- Surah 25 - Al Furqan THE CRITERION
- Surah 26 - Al Shu'ara' THE POETS
- Surah 27 - Al Naml THE ANTS
- Surah 28 - Al Qasas THE NARRATIONS
- Surah 29 - Al 'Ankabut THE SPIDER
- Surah 30 - Al Rum THE ROMANS
- Surah 31 - Luqman LUQMAN
- Surah 32 - Al Sajdah THE PROSTRATION
- Surah 33 - Al Ahzab THE CONFEDERATES
- Surah 34 - Saba' SHEBA
- Surah 35 - Fatir THE ORIGINATOR OF CREATION
- Surah 36 - Ya Sin YA SIN
- Surah 37 - Al Saffat THOSE RANGED IN RANKS
- Surah 38 - Sad SAD
- Surah 39 - Al Zumar CROWDS
- Surah 40 - Ghafir FORGIVER
- Surah 41 - Fussilat EXPOUNDED
- Surah 42 - Al Shura CONSULTATION
- Surah 43 - Al Zukhruf THE GOLD ADORNMENTS
- Surah 44 - Al Dukhan THE SMOKE
- Surah 45 - Al Jathiyah THE KNEELING DOWN
- Surah 46 - Al Ahqaf WINDING SAND-TRACTS
- Surah 47 - Muhammad MUHAMMAD
- Surah 48 - Al Fath THE VICTORY
- Surah 49 - Al Hujurat THE CHAMBERS
- Surah 50 - Qaf QAF
- Surah 51 - Al Dhariyat THE WINDS THAT SCATTER
- Surah 52 - Al Tur THE MOUNT
- Surah 53 - Al Najm THE STAR
- Surah 54 - Al Qamar THE MOON
- Surah 55 - Al Rahman THE MOST GRACIOUS
- Surah 56 - Al Waq'iah THE INEVITABLE
- Surah 57 - Al Hadid IRON
- Surah 58 - Al Mujadilah THE WOMAN WHO PLEADS
- Surah 59 - Al Hashr THE MUSTERING
- Surah 60 - Al Mumtahinah THAT WHICH EXAMINES
- Surah 61 - Al Saff THE BATTLE ARRAY
- Surah 62 - Al Jumu'ah FRIDAY
- Surah 63 - Al Munafiqun THE HYPOCRITES
- Surah 64 - Al Taghabun THE MUTUAL LOSS AND GAIN
- Surah 65 - Al Talaq DIVORCE
- Surah 66 - Al Tahrim PROHIBITION
- Surah 67 - Al Mulk THE DOMINION
- Surah 68 - Al Qalam THE PEN
- Surah 69 - Al Haqqah THE SURE REALITY
- Surah 70 - Al Ma'arij THE WAYS OF ASCENT
- Surah 71 - Nuh NOAH
- Surah 72 - Al Jinn THE SPIRITS
- Surah 73 - Al Muzzammil THE ENFOLDED ONE
- Surah 74 - Al Muddaththir THE ONE WRAPPED UP
- Surah 75 - Al Qiyamah THE RESURRECTION
- Surah 76 - Al Insan MAN
- Surah 77 - Al Mursalat THOSE SENT FORTH
- Surah 78 - Al Naba' THE GREAT NEWS
- Surah 79 - Al Nazi'at THOSE WHO TEAR OUT
- Surah 80 - 'Abasa HE FROWNED
- Surah 81 - Al Takwir THE FOLDING UP
- Surah 82 - Al Infitar THE CLEAVING ASUNDER
- Surah 83 - Al Mutaffifin THE DEALERS IN FRAUD
- Surah 84 - Al Inshiqaq THE RENDING ASUNDER
- Surah 85 - Al Buruj THE CONSTELLATIONS
- Surah 86 - Al Tariq THE NIGHT STAR
- Surah 87 - Al A'la THE MOST HIGH
- Surah 88 - Al Ghashiyah THE OVERWHELMING EVENT
- Surah 89 - Al Fajr THE DAWN
- Surah 90 - Al Balad THE CITY
- Surah 91 - Al Shams THE SUN
- Surah 92 - Al Layl THE NIGHT
- Surah 93 - Al Duha THE GLORIOUS MORNING LIGHT
- Surah 94 - Al Sharh THE EXPANSION OF THE BREAST
- Surah 95 - Al Tin THE FIG
- Surah 96 - Al Alaq THE CLINGING CLOT
- Surah 97 - Al Qadr THE NIGHT OF POWER
- Surah 98 - Al Bayyinah THE CLEAR EVIDENCE
- Surah 99 - Al Zalzalah THE EARTHQUAKE
- Surah 100 - Al 'Adiyat THOSE THAT RUN
- Surah 101 - Al Qari'ah THE GREAT CALAMITY
- Surah 102 - Al Takathur THE PILING UP
- Surah 103 - Al 'Asr TIME THROUGH THE AGES
- Surah 104 - Al Humazah THE SCANDALMONGER
- Surah 105 - Al Fil THE ELEPHANT
- Surah 106 - Quraysh THE TRIBE OF QURAYSH
- Surah 107 - Al Ma'un THE NEIGHBOURLY ASSISTANCE
- Surah 108 - Al Kawthar THE ABUNDANCE
- Surah 109 - Al Kafirun THOSE WHO REJECT FAITH
- Surah 110 - Al Nasr THE HELP
- Surah 111 - Al Masad THE PLAITED ROPE
- Surah 112 - Al Ikhlas THE PURITY OF FAITH
- Surah 113 - Al Falaq THE DAYBREAK
- Surah 114 - Al Nas MANKIND
- Acute Coronary Syndromes
- Angina Pectoris
- Anomalous Left Coronary Artery From the Pulmonary Artery
- Aortic Coarctation
- Aortic Dissection
- Aortic Regurgitation
- Aortic Stenosis
- Aortic Stenosis, Subaortic
- Aortic Stenosis, Supravalvar
- Ashman Phenomenon
- Atrial Fibrillation
- Atrial Flutter
- Atrial Myxoma
- Atrial Septal Defect
- Atrial Tachycardia
- Atrioventricular Block
- Atrioventricular Dissociation
- Atrioventricular Nodal Reentry Tachycardia (AVNRT)
- Benign Cardiac Tumors
- Brugada Syndrome
- Complications of Myocardial Infarction
- Coronary Artery Atherosclerosis
- Coronary Artery Vasospasm
- Digitalis Toxicity
- Dissection, Aortic
- Ebstein Anomaly
- Eisenmenger Syndrome
- First-Degree Atrioventricular Block
- HACEK Group Infections (Infective Endocarditis)
- Heart Failure - Decompensatio Cordis
- Holiday Heart Syndrome
- Hypertensive Heart Disease
- Junctional Rhythm
- Loeffler Endocarditis
- Long QT Syndrome
- Lutembacher Syndrome
- Mitral Regurgitation
- Mitral Stenosis
- Mitral Valve Prolapse
- Myocardial Infarction
- Myocardial Rupture
- Paroxysmal Supraventricular Tachycardia
- Patent Ductus Arteriosus
- Patent Foramen Ovale
- Pericardial Effusion
- Pericarditis Acute
- Pericarditis, Constrictive
- Pericarditis, Constrictive-Effusive
- Pulmonic Regurgitation
- Pulmonic Stenosis
- Right Ventricular Infarction
- Saphenous Vein Graft Aneurysms
- Second-Degree Atrioventricular Block
- Sinus of Valsalva Aneurysm
- Sudden Cardiac Death
- Tetralogy of Fallot
- Third-Degree Atrioventricular Block
- Torsade de Pointes
- Tricuspid Regurgitation
- Tricuspid Stenosis
- Unstable Angina
- Ventricular Fibrillation
- Ventricular Septal Defect
- Ventricular Tachycardia
- Wolff-Parkinson-White Syndrome