ECG Criteria
• P wave: Absent (P may be replaced by fibrillary f wave).
• Rhythm: Irregularly irregular (R-R interval is irregular). (Atrial rate is very high and ventricular rate is less).
According to the rate, atrial fibrillation may be of 2 types:
• Fast atrial fibrillation: Heart rate >100 beats/min.
• Slow atrial fibrillation: Heart rate <100 beats/min.
Q. What is atrial fibrillation?
Ans. It is an arrhythmia where atria beat rapidly, chaotically and ineffectively, while the ventricles respond at irregular intervals, producing the characteristic irregularly irregular pulse. Any conditions causing raised atrial pressure, increased atrial muscle mass, atrial fibrosis, inflammation and infiltration of the atrium can cause atrial fibrillation.
Q. What are the types of atrial fibrillation?
Ans. There are 3 types of atrial fibrillation:
• Paroxysmal: Discrete self-limiting episodes. May be persistent if underlying disease progresses.
• Persistent: Prolonged episode that can be terminated by electrical or chemical cardioversion.
• Permanent: Sinus rhythm cannot be restored.
Q. What are the causes of atrial fibrillation?
Ans. As follows:
• Chronic rheumatic heart disease with valvular lesions, commonly mitral stenosis (MS).
• Coronary artery disease (commonly, acute myocardial infarction).
• Thyrotoxicosis.
• Hypertension.
• Lone atrial fibrillation (idiopathic in 10% cases).
• Others—atrial septal defect (ASD), chronic constrictive pericarditis, acute pericarditis, cardiomyopathy, myocarditis, sick sinus syndrome, coronary bypass surgery, valvular surgery, acute chest infection (pneumonia), thoracic surgery, electrolyte imbalance (hypokalemia, hyponatremia), alcohol, pulmonary embolism.
NB: First 3 causes always top of the list.
Q. If the patient is young, what are the causes of atrial fibrillation?
Ans. As follows:
• Chronic rheumatic heart disease with valvular lesions, commonly mitral stenosis (MS).
• Thyrotoxicosis.
• Others—atrial septal defect (ASD), acute pericarditis, myocarditis, pneumonia.
Q. If the patient is elderly, what are the causes of atrial fibrillation?
Ans. As follows:
• Coronary artery disease (commonly acute myocardial infarction).
• Thyrotoxicosis.
• Hypertension.
• Lone atrial fibrillation (idiopathic in 10% cases).
• Others—see above (unusual or less in chronic rheumatic heart disease).
Q. What are the causes of temporary atrial fibrillation?
Ans. As follows:
• Acute myocardial infarction.
• Myocarditis (due to any cause).
• Pneumonia.
• Electrolyte imbalance.
Q. What are the complications of atrial fibrillation?
Ans. As follows:
• Systemic and pulmonary embolism (systemic from left atrium and pulmonary from right atrium). Annual risk is 5% (1 to 12%).
• Heart failure.
Q. What is lone atrial fibrillation?
Ans. Lone atrial fibrillation means atrial fibrillation without any cause. Genetic predisposition may be responsible.
• Fifty percent patients with paroxysmal atrial fibrillation and 20% with persistent or permanent atrial fibrillation have no cause and heart is normal.
• Lone atrial fibrillation usually occurs below 60 years of age.
• It may be intermittent, later may become permanent.
• Prognosis—low-risk of CVD (0.5% per year). Usually life span is normal.
Q. What history would you like to take in atrial fibrillation ?
Ans. I would take the history of:
• Rheumatic fever.
• Ischemic heart disease.
• History of thyrotoxicosis.
• Other history of any disease (according to cause).
Q. What are the clinical findings of atrial fibrillation?
Ans. As follows:
• Pulse—irregularly irregular (irregular in rhythm and volume).
• BP—may be hypertensive.
• Examination of heart (heart rate to see pulsus deficit, mitral valvular or other cardiac disease).
• Thyroid status (warm sweaty hands, tremor, tachycardia, exophthalmos, thyroid gland size).
Q. If a patient with AF is unconscious, what is the likely cause?
Ans. Cerebral embolism (usually with right sided hemiplegia).
Q. How to treat atrial fibrillation?
Ans. Aim of treatment is as follows:
• Control of heart rate.
• Restoration of sinus rhythm and prevention of recurrence.
• Treatment of primary cause.
Treatment (according to the type):
1. Paroxysmal atrial fibrillation:
• If asymptomatic: Does not require any treatment, follow-up the case.
• If troublesome symptoms are present: -blocker. Other drugs—flecainide or propafenone may be given. Amiodarone is effective in prevention. Low dose aspirin to prevent thromboembolism.
• If bradycardia is present (in sinoatrial disease): Permanent over drive atrial pacing (60% effective).
• In some intractable cases: Radiofrequency ablation may be required, who does not have structural heart disease (70% effective).
2. Persistent atrial fibrillation:
• Control of heart rate: B-blocker, digoxin or calcium channel blocker (verapamil, diltiazem). Combination of digoxin and atenolol may be used.
• To control rhythm: DC cardioversion may be done safely. It may be repeated, if relapse occurs. Concomitant use of B-blocker or amiodarone may be used to prevent recurrence.
3. Permanent atrial fibrillation:
• Control of heart rate: Digoxin, -blocker, calcium channel blocker (verapamil or diltiazem).
• In some cases: Transvenous radiofrequency ablation may be done (it induces complete heart block. So, permanent pacemaker should be given).
Q. What is the role of anticoagulant in atrial fibrillation ?
Ans. Usually, warfarin is given who are at risk of stroke. Target INR is 2 to 3. It reduces stroke in 2/3rd cases. Aspirin reduces stroke in 1/5th cases. Anticoagulation is indicated in patient with atrial fibrillation having risk factors for thromboembolism.
Risk factors for thromboembolism in atrial fibrillation:
• Previous ischemic stroke or TIA
• Mitral valve disease.
• Age over 65 years.
• Hypertension.
• Diabetes mellitus.
• Heart failure.
• Echocardiographic evidence of left ventricular dysfunction, left atrial enlargement or mitral anular calcification.
Risk groups with thromboembolism (nonrheumatic)
• Very high: Previous stroke or TIA (12%).
• High: Age > 65 years and one other risk factor (6.5%).
• Moderate: (i) Age > 65 years, no risk factor (4%), (ii) Age < 65 years, other risk factor (4%).
• Low: Age < 65 years, no risk factor (1.2%).
No comments:
Post a Comment